Cancer stem cells (CSCs), which have the potential for self-renewal, differentiation and de-differentiation, undergo epigenetic, epithelial-mesenchymal, immunological and metabolic reprogramming to adapt to the tumor microenvironment and survive host defense or therapeutic insults. Intra-tumor heterogeneity and cancer-cell plasticity give rise to therapeutic resistance and recurrence through clonal replacement and reactivation of dormant CSCs, respectively. WNT signaling cascades cross-talk with the FGF, Notch, Hedgehog and TGFβ/BMP signaling cascades and regulate expression of functional CSC markers, such as CD44, CD133 (PROM1), EPCAM and LGR5 (GPR49). Aberrant canonical and non-canonical WNT signaling in human malignancies, including breast, colorectal, gastric, lung, ovary, pancreatic, prostate and uterine cancers, leukemia and melanoma, are involved in CSC survival, bulk-tumor expansion and invasion/metastasis. WNT signaling-targeted therapeutics, such as anti-FZD1/2/5/7/8 monoclonal antibody (mAb) (vantictumab), anti-LGR5 antibody-drug conjugate (ADC) (mAb-mc-vc-PAB-MMAE), anti-PTK7 ADC (PF-06647020), anti-ROR1 mAb (cirmtuzumab), anti-RSPO3 mAb (rosmantuzumab), small-molecule porcupine inhibitors (ETC-159, WNT-C59 and WNT974), tankyrase inhibitors (AZ1366, G007-LK, NVP-TNKS656 and XAV939) and β-catenin inhibitors (BC2059, CWP232228, ICG-001 and PRI-724), are in clinical trials or preclinical studies for the treatment of patients with WNT-driven cancers. WNT signaling-targeted therapeutics are applicable for combination therapy with BCR-ABL, EGFR, FLT3, KIT or RET inhibitors to treat a subset of tyrosine kinase-driven cancers because WNT and tyrosine kinase signaling cascades converge to β-catenin for the maintenance and expansion of CSCs. WNT signaling-targeted therapeutics might also be applicable for combination therapy with immune checkpoint blockers, such as atezolizumab, avelumab, durvalumab, ipilimumab, nivolumab and pembrolizumab, to treat cancers with immune evasion, although the context-dependent effects of WNT signaling on immunity should be carefully assessed. Omics monitoring, such as genome sequencing and transcriptome tests, immunohistochemical analyses on PD-L1 (CD274), PD-1 (PDCD1), ROR1 and nuclear β-catenin and organoid-based drug screening, is necessary to determine the appropriate WNT signaling-targeted therapeutics for cancer patients.
Cancer stem cells (CSCs), which show the potential for self-renewal and differentiation, have been identified in a variety of human cancers based on their tumor initiating potential in vivo (1–3). Clonal expansion of a minor CSC population with a drug-resistant mutation causes early recurrence, whereas reactivation of dormant CSCs into cycling CSCs owing to tumor plasticity leads to late relapse (4–6). CSCs or bulk tumor cells undergo epigenetic reprogramming (7), epithelial-mesenchymal reprogramming [epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET)] (8,9), immunological reprogramming (immunoediting) (10,11) and metabolic reprogramming (12) to adapt to the tumor microenvironment, which is collectively defined here as 'omics reprogrammming' (Fig. 1). Since cycling CSCs that depend on aerobic glycolysis converge into quiescent mesenchymal CSCs through omics reprogramming to survive therapeutic insult for later recurrence, CSC targeting is necessary to avoid relapse after cancer therapy and improve the cost-effectiveness ratio of cancer precision medicine.
CD44, CD133 (PROM1), EPCAM and LGR5 (GPR49) are representative cell-surface markers of CSCs (2,13–16). LGR5, encoding an R-spondin (RSPO) receptor, is a target gene of the canonical WNT/β-catenin signaling cascade in quiescent as well as cycling stem cells, whereas CD44 and CD133 are further upregulated by WNT and RSPO signals in LGR5+ cycling stem/progenitor cells (17–19). EPCAM can potentiate the canonical WNT/β-catenin signaling cascade through intra-membrane proteolysis and subsequent nuclear translocation of its intracellular C-terminal domain (20). WNT signaling cascades cross-talk with the FGF, Notch, Hedgehog and TGFβ/BMP signaling cascades to constitute the stem cell signaling network, which regulates expression of functional CSC markers (21–24).
The WNT family proteins transduce signals through the Frizzled (FZD) and LRP5/6 receptors to the WNT/β-catenin and WNT/STOP (stabilization of proteins) signaling cascades (also known as the canonical WNT signaling cascades) and through the FZD and/or ROR1/ROR2/RYK receptors to the WNT/PCP (planar cell polarity), WNT/RTK (receptor tyrosine kinase) and WNT/Ca2+ signaling cascades (also known as the non-canonical WNT signaling cascades) (21,25–29). The canonical WNT/β-catenin signaling cascade is involved in self-renewal of stem cells and proliferation or differentiation of progenitor cells (30–33), whereas non-canonical WNT signaling cascades are involved in maintenance of stem cells, directional cell movement or inhibition of the canonical WNT signaling cascade (34–37). Both canonical and non-canonical WNT signaling cascades play key roles in the development and evolution of CSCs.
By contrast, tumors consist of heterogeneous populations of cancer cells and non-cancerous stromal/immune cells (38,39). Intra-tumor heterogeneity of cancer cells is caused by the evolution of CSCs based on epigenetic and genetic alterations (40–42), as well as the differentiation of CSCs into bulk tumor cells (1–3), niche-like cancer supporting cells (43), endothelial-like cancer cells (44) and fibroblast-like cancer cells (45). On the other hand, intra-tumor heterogeneity of non-cancerous stromal/immune cells is orchestrated by and reciprocally orchestrates CSCs and their descendants (39,45–47). Interaction and co-evolution of CSCs and niche cells are driving forces of cancer progression. Herein, canonical and non-canonical WNT signaling in CSCs will be described, with a focus on the heterogeneity of cancer and stromal/immune cells in the tumor microenvironment; then, anti-CSC mono- and combination therapies using WNT signaling-targeted therapeutics will be reviewed with emphases on omics reprogramming and tumor plasticity.
2. Canonical WNT signaling in CSCs and their niches
Canonical WNT signaling through the FZD-LRP5/6 receptor complex leads to de-repression of β-catenin as well as STOP-target proteins, such as ATOH1, CCND1 (Cyclin D1), FOXM1, MYC (c-MYC), NRF2 (NFE2L2), PLK1, SMAD1/3/4, SNAI1 (Snail) and YAP/TAZ, from proteasomal degradation induced by GSK-3β-dependent phosphorylation and subsequent ubiquitylation (27–29,48) (Fig. 2). β-catenin stabilization and subsequent nuclear translocation leads to transcriptional activation of β-catenin-TCF/LEF target genes, such as ATOH1, CCND1, CD44, FGF20, JAG1, LGR5, MYC and SNAI1, although transcriptional outputs of the WNT/β-catenin signaling cascade are determined in a cellular context-dependent manner (e.g., epigenetic status of target genes and activities of other transcriptional regulators). ATOH1, CCND1, MYC and SNAI1 are upregulated transcriptionally and post-translationally by the β-catenin and STOP signaling cascades, respectively. Canonical WNT signals control cell fate and function through transcriptional and post-translational regulation of the omics network.
Canonical WNT signaling in CSCs is activated by WNT2B, WNT3 and other canonical WNT ligands derived from cancerous supporting cells or non-cancerous stromal cells (49–52), as well as genetic alterations in the canonical WNT/β-catenin signaling components, such as EIF3E-RSPO2 fusions, PTPRK-RSPO3 fusions, gain-of-function mutations in the CTNNB1 (β-catenin) gene and loss-of-function mutations in the APC, AXIN1, AXIN2, RNF43 and ZNRF3 genes (29,53–55). Canonical WNT signals increase the LGR5 receptor level on CSCs for the maintenance of the canonical WNT responsive state but also upregulate AXIN2, DKK1, NOTUM, RNF43 and ZNRF3 for negative feedback regulation (18–21,29). Loss-of-function mutations in the APC, AXIN2, RNF43 and ZNRF3 genes release CSCs from the constraints of the negative feedback regulation.
Canonical WNT signals can directly promote CSC proliferation through upregulation of CCND1, FOXM1, MYC and YAP/TAZ as described above. By contrast, canonical WNT signaling in CSCs induces expression and secretion of growth factors, such as FGFs, KIT ligand (KITLG or SCF) and VEGF (VEGFA), to fine-tune the tumor microenvironment (18,21,29). For example, MET (HGF receptor) is upregulated in human basal-like breast cancers with TP53 mutations as well as mouse basal-like breast tumors with compound gain-of-function Ctnnb1 mutation and homozygous Tp53 deletion (56), and combined activation of the canonical WNT/β-catenin and HGF/MET signaling cascades induces SHH upregulation in mouse mammary CSCs and subsequent activation of cancer-associate fibroblasts for the synergistic proliferation of CSCs and cancer-associate fibroblasts (57).
Together, these findings indicate that canonical WNT signaling is involved in the maintenance and expansion of CSCs through direct effects on CSCs themselves and indirect effects via CSC-stromal/immune interactions.
3. Non-canonical WNT signaling in CSCs and their niches
Non-canonical WNT signaling through FZD receptors and/or ROR1/ROR2/RYK co-receptors activates the PCP, RTK or Ca2+ signaling cascades (Fig. 2).
Non-canonical WNT/PCP signaling through FZD receptors and Dishevelled (DVL) adaptor proteins regulates the coordinated cellular orientation within an epithelial plane, collective cell movements during gastrulation and neurulation stages of embryogenesis and directional cell movement during invasion and metastasis of cancer cells (58–62). WNT/PCP signals are converted to actin cytoskeletal dynamics via the small G-proteins RAC and RHO (Fig. 2), and then, RAC and RHO activate JNK-dependent transcription and YAP/TAZ-dependent transcription, respectively (63–66). WNT/PCP signaling regulates actin cytoskeletal dynamics, directional cell movement and JNK- or YAP/TAZ-dependent transcription.
Non-canonical WNT signaling through RTKs, such as ROR1, ROR2 and RYK, activates the PI3K-AKT signaling cascade (29,67–69). ROR1 and ROR2, with the extracellular WNT-binding FZD-like domain, are homologous to MUSK, NTRK1, NTRK2, NTRK3, DDR1 and DDR2 in their cytoplasmic tyrosine kinase domain, whereas RYK with an extracellular WNT-binding WIF domain is homologous to AXL, EGFR, ERBB2, ERBB3, ERBB4, MET, MERTK, MST1R and TYRO3 in its cytoplasmic tyrosine kinase domain (39,70–73). ROR1 and ROR2 are atypical RTKs that are defective in intrinsic tyrosine kinase activity for auto-phosphorylation; however, ROR1 and ROR2 can be tyrosine phosphorylated by other tyrosine kinases, such as EGFR, ERBB3, MET and SRC, to activate the PI3K-AKT and YAP signaling cascades (29,74–78) (Fig. 2). WNT/RTK signaling is involved in therapeutic resistance and recurrence of human cancers in part through PI3K-AKT signaling activation.
Non-canonical WNT signals induce cytosolic Ca2+ elevation through Ca2+ release from the endoplasmic reticulum or Ca2+ influx from the extracellular space. WNT signaling through Frizzled receptors are involved in Ca2+ release from the endoplasmic reticulum via small G-protein- or SEC14L2-mediated activation of phospholipase C (PLC) and subsequent generation of inositol-1,4,5-triphosphate (IP3) (21,79–81). WNT signaling through Polycystin 1 (PKD1) is proposed to induce Ca2+ influx through a TRPP2 Ca2+ channel (82). Ca2+/Calmodulin-dependent protein kinase II (CAMK2) and Calcineurin are representative downstream effectors of the WNT/Ca2+ signaling cascade (Fig. 2). For example, WNT/Ca2+ signaling-dependent CAMK2 activation leads to phosphorylation and activation of Nemo-like kinase (NLK), which can inhibit canonical WNT/β-catenin signaling in some cells (83). WNT-dependent CamK2 activation in cardiomyocytes gives rise to cardiac hypertrophy through phosphorylation and cytoplasmic tethering of Hdac4 and subsequent de-repression of Mef2 target genes (84). WNT/Ca2+ signaling-dependent Calcineurin activation leads to dephosphorylation and subsequent nuclear translocation of NFAT for the transcriptional activation of NFAT-target genes (85). By contrast, KRAS-dependent FZD8 repression in pancreatic cancer cells leads to potentiation of tumorigenesis through WNT/Ca2+ signaling inhibition (37). WNT/Ca2+ signaling to downstream effectors, such as CAMK2 and Calcineurin, is involved in a variety of cellular processes through transcriptional activation of NFAT-target genes, de-repression of MEF2-target genes and repression WNT/β-catenin-target genes in a cellular context-dependent manner.
Non-canonical WNT signaling in CSCs is activated by WNT5A, WNT11 and other non-canonical WNT ligands (58) that are secreted from cancer cells (86,87) or stromal/immune cells (88,89), as well as genetic alterations that trans-activate non-canonical WNT signaling cascades, such as E2A-PBX1 fusion and MET amplification (74–76). Non-canonical WNT signaling through FZD7 activates the PI3K-AKT signaling cascade as a result of Daple (CCDC88C)-mediated dissociation of Gβγ from Gαi (90), whereas non-canonical WNT signaling through ROR1 activates PI3K-AKT signaling cascade owing to ROR1 trans-phosphorylation by other tyrosine kinases, such as MET and SRC (67,75). ROR1 is involved in HER3-Y1307 trans-phosphorylation and subsequent NSUN6-dependent MST1-K59 methylation, which induces YAP/TAZ-dependent transcriptional activation through LATS1/LATS2 inhibition (78). WNT/PCP signaling can also induce Rho-mediated LATS1/LATS2 inhibition for transcriptional activation of YAP/TAZ-target genes (91,92), whereas non-canonical WNT signaling through FZD10 induces YAP/TAZ activation through Gα13 (93). Non-canonical WNT signaling promotes survival and therapeutic resistance of CSCs through PI3K-AKT signaling activation and YAP/TAZ-mediated transcriptional activation.
By contrast, invasion and metastasis are driven by canonical WNT signaling cascades and non-canonical WNT signaling cascades. For example, canonical WNT/β-catenin and WNT/STOP signaling cascades synergistically upregulate SNAI1 to repress epithelial genes, such as CDH1 (E-cadherin), for the initiation of EMT of CSCs, and non-canonical WNT signals promote invasion, survival and metastasis of CSCs or circulating tumor cells (28,29,35,62,87). Together, these findings clearly indicate that canonical WNT/β-catenin signaling as well as other WNT signaling cascades are critically involved in the malignant features of CSCs.
WNT signaling cascades are hot and cutting-edge topics in the field of translational oncology and medicinal chemistry (29,94–96). Therapeutics directly targeting WNT signaling cascades are classified into i) ligand/receptor-targeted drugs binding to ligands or transmembrane proteins involved in WNT signaling, ii) porcupine (PORCN) inhibitors abrogating WNT secretion and FZD-dependent signaling, iii) tankyrase (TNKS) inhibitors repressing WNT/β-catenin and WNT-independent signaling cascades and iv) β-catenin inhibitors blocking TCF/LEF-dependent transcription (Table I).
Human/humanized monoclonal antibody (mAb) drugs, such as anti-FZD1/2/5/7/8 mAb (vantictumab/OMP-18R5) (97), anti-FZD5 mAb (IgG-2919) (52), anti-FZD10 antibody-drug conjugate (ADC) (OTSA101-DTPA-90Y) (98), anti-LGR5 ADC (mAb-mc-vc-PAB-MMAE) (99), anti-PTK7 ADC (PF-06647020) (100), anti-ROR1 mAb (cirmtuzumab/UC-961) (101) and anti-RSPO3 mAb (rosmantuzumab/OMP-131R10) (102) have been developed as large-molecule cancer therapeutics. ROR1 CAR-T cells (103) and WNT-trapping FZD8-Fc chimeric protein (ipafricept/OMP-54F28) (104) are also classified as WNT ligand/receptor-targeted drugs. Among this class of therapeutics, cirmtuzumab, ipafricept, PF-06647020, rosmantuzumab and vantictumab, which showed anti-CSC effects in preclinical model experiments, are in clinical trials to treat cancer patients (Table I).
PORCN inhibitors restrain PORCN-dependent palmitoleoylation of WNT family ligands in the endoplasmic reticulum, which obstructs WNT signaling through blockade of WNT secretion as well as palmitoleoylated WNT-mediated oligomerization of FZD receptors (105–108). ETC-159 (109), IWP-2 (110), WNT-C59 (111) and WNT974 (LGK974) (112) are small-molecule PORCN inhibitors. A preclinical study of IWP-2 on organoids derived from colorectal cancer patients revealed that PORNC inhibitors are applicable for the treatment of cancers with RNF43 mutations but not APC mutations (52). By contrast, preclinical studies of WNT974 indicated that PORNC inhibitors repress the survival and tumor initiating potential of CSCs (43,112). ETC-159 and WNT974 are in clinical trials for the treatment of cancer patients (Table I).
TNKS inhibitors repress TNKS-dependent poly-ADP-ribosylation and subsequent degradation of negative regulators of oncogenic signaling cascades, such as AXIN family proteins, AMOT family proteins, PTEN and TERF1 (TRF1), which results in inhibition of WNT/β-catenin signaling, repression of YAP-dependent transcription, suppression of PI3K signaling and telomere shortening, respectively (113–116). AZ1366 (117), G007-LK (118), JW55 (119), NVP-TNKS656 (120) and XAV939 (121) are representative TNKS inhibitors that abrogate WNT/β-catenin signaling and tumorigenesis in preclinical mouse model experiments. TNKS inhibitors show synergistic antitumor effects with other therapeutics, such as an AKT inhibitor (API2), EGFR inhibitors (gefitinib and erlotinib), a MEK inhibitor (AZD6244), a PI3K inhibitor (BKM120) and irinotecan (117,118,120,122–124). TNKS inhibitors are promising candidates for CSC-targeted therapeutics; however, because of diverse on-target effects, TNKS inhibitors stalled in their preclinical stage.
β-catenin inhibitors block TCF/LEF-dependent transcription through inhibition of protein-protein interactions (PPI) between β-catenin and other transcriptional regulators (29,125), promotion of β-catenin degradation (126) or inhibition of β-catenin kinases, such as TNIK (127–129). BC2059 (130), CGP049090 (131), CWP232228 (132), ICG-001 (133), LF3 (134), PKF115–584 (135), PRI-724 (136) and SAH-BCL9 (137) are small-molecule β-catenin PPI inhibitors. MSAB is a small-molecule compound that binds to β-catenin and promotes proteasomal degradation of β-catenin (126). KY-05009 (128), mebendazole (129) and PF-794 (138) are TNIK inhibitors that repress phosphorylation of TNIK substrates, such as TCF4, FMNL2, PRICKLE1, SMAD1 and SMAD2, which leads to inhibition of β-catenin-TCF/LEF-dependent transcription and a variety of cellular processes. Among the β-catenin inhibitors mentioned above, BC2059, CWP232228 and ICG-001 repress the expansion of CSCs. The β-catenin inhibitors PRI-724 and mebendazole are in phase I/II clinical trials for cancer patients (Table I), whereas other β-catenin inhibitors are still in the preclinical stage of drug development. β-catenin inhibitors are challenging therapeutics for cancer patients.
WNT signaling cascades are the major driver of various types of human cancers (29), but the development of many WNT signaling-targeted therapeutics is stuck in the preclinical stage or phase I/II stages of clinical trials (Table I) because of the complexity of WNT signaling cascades and genetic alterations in non-enzymatic signaling components. MAb-based drugs and PORCN inhibitors with the potential to target CSCs as well as bulk cancer cells are promising therapeutics for the patients with WNT signaling-driven cancers.
5. Anti-CSC combination therapy using WNT signaling-targeted drugs
Tyrosine kinase inhibitors are rational anticancer therapeutics because tyrosine kinases with intrinsic enzyme activities are aberrantly activated in cancer cells owing to genetic alterations. Tyrosine kinase inhibitors have contributed to the improved prognosis of cancer patients and are essential for genome-based precision medicine; however, unavoidable drug resistance or recurrence is a serious issue for cancer patients and health care systems (4).
Activated tyrosine kinases, such as BCR-ABL fusion kinase, EGFR-T790M mutant, FLT3 internal tandem duplication (FLT3-ITD) mutant, KIT-D814V mutant and RET, promote β-catenin phosphorylation at Y654 to release E-cadherin-bound β-catenin from the adherens junction for its stabilization and subsequent nuclear translocation (139–143). By contrast, canonical WNT signals inhibit β-catenin phosphorylation at S33, S37, T41 and S45 to release β-catenin from proteasomal degradation for its stabilization and nuclear translocation (21,25,26,29). Since canonical WNT signals and oncogenic tyrosine kinases converge to β-catenin stabilization for the maintenance and expansion of CSCs, canonical WNT signaling inhibitors can block CSC evasion of tyrosine kinase inhibitors. For example, the porcupine inhibitor WNT974 significantly reduced residual stem/progenitor cells of chronic myeloid leukemia (CML) after treatment with the BCR-ABL inhibitor nilotinib via blockade of WNT ligand secretion into the bone marrow microenvironment (112); the β-catenin inhibitors ICG-001 and PRI-724 induced synergistic effects with the BCR-ABL inhibitors imatinib and nilotinib, respectively, on CML stem/progenitor cells (136,144); and the TNKS inhibitor AZ1366 and EGFR inhibitor gefitinib showed synergistic effects on lung cancer cells in vivo (124). These preclinical studies indicate that combination therapies using WNT signaling-targeted therapeutics and tyrosine kinase inhibitors might be applicable for treatment of a subset of patients with tyrosine kinase-driven cancers (Fig. 3).
Immune checkpoint blockers that abrogate interactions of ligands and inhibitory receptors on CD8+ T cells are promising antitumor drugs in the clinic or clinical trials (145–151). PD-L1 (CD274) is a representative ligand for inhibitory immune signaling, whereas PD-1 (PDCD1) and CTLA4 are representative receptors for inhibitory immune signaling. Anti-PD-L1 mAbs (atezolizumab, avelumab and durvalumab), anti-PD-1 mAbs (nivolumab and pembrolizumab) and an anti-CTLA4 mAb (ipilimumab) are approved for the treatment of patients with melanoma or other types of solid tumors. Immune checkpoint blockers result in significant therapeutic effects in a subset of patients; however, the lack of benefits in other patients owing to primary or acquired resistance to immune checkpoint blockers has resulted in a cost-effectiveness issue (152–156).
Canonical WNT signaling activation in melanoma induces immune evasion through CCL4 repression and immunological reprogramming into non-T cell-infiltrated melanoma (11). Since melanoma-derived WNT5A promotes β-catenin signaling activation and subsequent IDO upregulation in dendritic cells to induce immune evasion through accumulation of regulatory T (Treg) cells, combination immunotherapy using the porcupine inhibitor WNT-C59 and anti-CTLA4 mAb showed synergistic anti-melanoma effects in vivo (157). By contrast, WNT5A and ROR2 are relatively frequently upregulated in pretreatment tumors of melanoma patients that do not respond to PD-1 immune checkpoint blockade (158), which suggests involvement of non-canonical WNT signaling in resistance to immune checkpoint blockers. Since DKK1-dependent canonical WNT signaling inhibition or putative reciprocal non-canonical WNT signaling activation in tumor microenvironment induces immune evasion through accumulation of myeloid-derived suppressor cells (MDSCs) and depletion of T cells (159), combination therapy using anti-DKK1 mAb (BHQ880 or DKN-01) (160,161) and immune checkpoint blockers might show synergistic antitumor effects in vivo. WNT signaling-targeted therapeutics might be applicable for combination immunotherapy for cancer patients (Fig. 3); however, context-dependent effects of WNT signaling on immunity (4) should be kept in mind.
6. Omics monitoring for WNT signaling-targeted therapy
WNT-related human cancers are classified into three major subtypes based on signaling aberrations associated with therapeutic choices (Fig. 3): APC/CTNNB1-altered cancers with WNT/β-catenin signaling activation that can be treated with β-catenin inhibitors; RNF43/ZNRF3/RSPO2/RSPO3-altered cancers with WNT/β-catenin and other WNT signaling activation that can be treated with PORCN inhibitors, anti-FZD mAb or anti-RSPO3 mAb; and ROR1-upregulated cancers with WNT/PCP and WNT/RTK signaling activation that can be treated with anti-ROR1 mAb, anti-ROR1 × CD3 bispecific antibody and ROR1 chimeric antigen receptor-modified T (CAR-T) cells (29). Genome sequencing, transcriptomic and/or immunohistochemical tests are necessary for the detection and subtyping of WNT signaling-driven cancers and subsequent determination of appropriate WNT signaling-targeted therapeutics (Fig. 3).
WNT signaling-targeted therapeutics are also applicable for combination therapies with tyrosine kinase inhibitors or immune checkpoint blockers as mentioned above (Fig. 3). Since resistance to tyrosine kinase inhibitors occur owing to multiple mechanisms, such as acquired drug-resistant mutations in targeted tyrosine kinases, EMT, activation of other tyrosine kinase signaling cascades to bypass targeted tyrosine kinases (4,162) and activation of WNT/β-catenin signaling cascade (Fig. 3), genomic, transcriptomic and/or immunohistochemical monitoring during tyrosine kinase inhibitor treatment is also necessary to identify a subset of patients for combination therapy with tyrosine kinase inhibitor and WNT signaling-targeted therapeutics. By contrast, because WNT signaling in the tumor microenvironment orchestrates antitumor immunity and immune tolerance in a context-dependent manner, immune monitoring is necessary to choose the appropriate WNT signaling-targeted therapeutics for cancer patients with immune evasion (Fig. 3).
Investigational genome medicine platforms based on nucleotide sequencing of transcribed regions are applicable for determination of targeted therapeutics only in 10–24% of cancer patients (163,164). Since alterations in non-transcribed regulatory regions also drive human carcinogenesis, whole-genome sequencing rather than whole- or partial-exome sequencing is preferable to improve the precision of genome-based medicine (4,165). In addition, organoid culture is a cutting-edge technology in the fields of oncology and stem cell biology (166–168), and organoid-based tests are also used for selecting targeted therapeutics (163,166). However, because tumor-stromal/immune interactions are not recapitulated in patient-derived organoid models, immunological monitoring in the tumor microenvironment is also necessary to improve genome-based medicine.
Together, these findings indicate that 'omics monitoring', including genome sequencing, transcriptomic, immunohistochemical and organoid-based tests, before and during treatment is necessary to choose and fine-tune WNT signaling-targeted therapeutics for the treatment of cancer patients (Fig. 3).
7. Conclusion
Cancer stem cells (CSCs) are part of the tumor microenvironment and survive host defense or therapeutic insult through omics reprogramming. Aberrant WNT signaling activation in human cancers promotes CSC survival, bulk-tumor expansion and invasion/metastasis. Anti-FZD mAb, anti-ROR1 mAb, anti-RSPO3 mAb, PORCN inhibitors and β-catenin inhibitors are representative WNT signaling-targeted therapeutics in clinical trials or preclinical studies. WNT signaling-targeted therapeutics are applicable for combination therapy with tyrosine kinase inhibitors or immune checkpoint blockers. Omics monitoring is necessary for therapeutic optimization of WNT signaling-targeted therapy.
Acknowledgments
This study was financially supported in part by a grant-in-aid for the Knowledgebase Project from M. Katoh's Fund.
ReferencesVisvaderJELindemanGJCancer stem cells in solid tumours: Accumulating evidence and unresolved questions8755768200810.1038/nrc249918784658MedemaJPCancer stem cells: The challenges ahead15338344201310.1038/ncb271723548926AbbaszadeganMRBagheriVRazaviMSMomtaziAASahebkarAGholaminMIsolation, identification, and characterization of cancer stem cells: A review23220082018201710.1002/jcp.25759KatohMTherapeutics targeting FGF signaling network in human diseases3710811096201610.1016/j.tips.2016.10.00327992319de Sousa e MeloFKurtovaAVHarnossJMKljavinNHoeckJDHungJAndersonJEStormEEModrusanZKoeppenHA distinct role for Lgr5(+) stem cells in primary and metastatic colon cancer543676680201710.1038/nature2171328358093KouryJZhongLHaoJTargeting signaling pathways in cancer stem cells for cancer treatment20172925869201710.1155/2017/2925869283569145357538McDonaldOGLiXSaundersTTryggvadottirRMentchSJWarmoesMOWordAECarrerASalzTHNatsumeSEpigenomic reprogramming during pancreatic cancer progression links anabolic glucose metabolism to distant metastasis49367376201710.1038/ng.375328092686TamWLWeinbergRAThe epigenetics of epithelial-mesenchymal plasticity in cancer1914381449201310.1038/nm.3336242023964190672GonzalezDMMediciDSignaling mechanisms of the epithelial-mesenchymal transition7re8201410.1126/scisignal.2005189252496584372086SchreiberRDOldLJSmythMJCancer immunoediting: Integrating immunity's roles in cancer suppression and promotion33115651570201110.1126/science.120348621436444SprangerSBaoRGajewskiTFMelanoma-intrinsic β-catenin signalling prevents anti-tumour immunity523231235201510.1038/nature1440425970248CairnsRAHarrisISMakTWRegulation of cancer cell metabolism118595201110.1038/nrc298121258394O'BrienCAPollettAGallingerSDickJEA human colon cancer cell capable of initiating tumour growth in immunodeficient mice445106110200710.1038/nature05372YamashitaTJiJBudhuAForguesMYangWWangHYJiaHYeQQinLXWauthierEEpCAM-positive hepatocellular carcinoma cells are tumor-initiating cells with stem/progenitor cell features13610121024200910.1053/j.gastro.2008.12.004191503502828822TodaroMGaggianesiMCatalanoVBenfanteAIovinoFBiffoniMApuzzoTSperdutiIVolpeSCocorulloGCD44v6 is a marker of constitutive and reprogrammed cancer stem cells driving colon cancer metastasis14342356201410.1016/j.stem.2014.01.00924607406HirschDBarkerNMcNeilNHuYCampsJMcKinnonKCleversHRiedTGaiserTLGR5 positivity defines stem-like cells in colorectal cancer35849858201410.1093/carcin/bgt3773977143Van der FlierLGSabates-BellverJOvingIHaegebarthADe PaloMAntiMVan GijnMESuijkerbuijkSVan de WeteringMMarraGThe intestinal Wnt/TCF signature132628632200710.1053/j.gastro.2006.08.03917320548YanKSJandaCYChangJZhengGXYLarkinKALucaVCChiaLAMahATHanATerryJMNon-equivalence of Wnt and R-spondin ligands during Lgr5(+) intestinal stem-cell self-renewal545238242201710.1038/nature2231328467820HilkensJTimmerNCBoerMIkinkGJScheweMSacchettiAKoppensMAJSongJYBakkerERMRSPO3 expands intestinal stem cell and niche compartments and drives tumorigenesis6610951105201710.1136/gutjnl-2016-3116065532462ManiSKZhangHDiabAPascuzziPELefrançoisLFaresNBancelBMerlePAndrisaniOEpCAM-regulated intra-membrane proteolysis induces a cancer stem cell-like gene signature in hepatitis B virus-infected hepatocytes65888898201610.1016/j.jhep.2016.05.022272387555289705KatohMKatohMWNT signaling pathway and stem cell signaling network1340424045200710.1158/1078-0432.CCR-06-231617634527RanganathanPWeaverKLCapobiancoAJNotch signalling in solid tumours: A little bit of everything but not all the time11338351201110.1038/nrc303521508972KatohMNakagamaHFGF receptors: Cancer biology and therapeutics34280300201410.1002/med.21288LambRBonuccelliGOzsváriBPeiris-PagèsMFiorilloMSmithDLBevilacquaGMazzantiCMMcDonnellLANaccaratoAGMitochondrial mass, a new metabolic biomarker for stem-like cancer cells: Understanding WNT/FGF-driven anabolic signaling63045330471201510.18632/oncotarget.5852264217114741544NiehrsCThe complex world of WNT receptor signalling13767779201210.1038/nrm347023151663HollandJDKlausAGarrattANBirchmeierWWnt signaling in stem and cancer stem cells25254264201310.1016/j.ceb.2013.01.00423347562RadaPRojoAIOffergeldAFengGJVelasco-MartínJPGonzález-SanchoJMValverdeÁMDaleTRegaderaJCuadradoAWNT-3A regulates an Axin1/NRF2 complex that regulates antioxidant metabolism in hepatocytes22555571201510.1089/ars.2014.60404333636AcebronSPNiehrsCβ-catenin-independent roles of Wnt/LRP6 signaling26956967201610.1016/j.tcb.2016.07.00927568239KatohMKatohMMolecular genetics and targeted therapy of WNT-related human diseases (Review)405876062017287311485547940LuiJHHansenDVKriegsteinARDevelopment and evolution of the human neocortex1461836201110.1016/j.cell.2011.06.030217297793610574BarkerNAdult intestinal stem cells: Critical drivers of epithelial homeostasis and regeneration151933201410.1038/nrm3721Van CampJKBeckersSZegersDVan HulWWnt signaling and the control of human stem cell fate10207229201410.1007/s12015-013-9486-8YangKWangXZhangHWangZNanGLiYZhangFMohammedMKHaydonRCLuuHHThe evolving roles of canonical WNT signaling in stem cells and tumorigenesis: Implications in targeted cancer therapies96116136201610.1038/labinvest.2015.1444731283QinLYinYTZhengFJPengLXYangCFBaoYNLiangYYLiXJXiangYQSunRWNT5A promotes stemness characteristics in nasopharyngeal carcinoma cells leading to metastasis and tumorigenesis61023910252201510.18632/oncotarget.3518258239234496352WebsterMRKugelCHIIIWeeraratnaATThe Wnts of change: How Wnts regulate phenotype switching in melanoma18562442512015265462684668201KumawatKGosensRWNT-5A: Signaling and functions in health and disease73567587201610.1007/s00018-015-2076-y4713724WangMTHolderfieldMGaleasJDelrosarioRToMDBalmainAMcCormickFK-Ras promotes tumorigenicity through suppression of non-canonical Wnt signaling16312371251201510.1016/j.cell.2015.10.04126590425PlaksVKongNWerbZThe cancer stem cell niche: How essential is the niche in regulating stemness of tumor cells?16225238201510.1016/j.stem.2015.02.015257489304355577KatohMFGFR inhibitors: Effects on cancer cells, tumor microenvironment and whole-body homeostasis (Review)38315201610.3892/ijmm.2016.2620272451474899036BolliNAvet-LoiseauHWedgeDCVan LooPAlexandrovLBMartincorenaIDawsonKJIorioFNik-ZainalSBignellGRHeterogeneity of genomic evolution and mutational profiles in multiple myeloma52997201410.1038/ncomms3997244297033905727LiSGarrett-BakelmanFEChungSSSandersMAHricikTRapaportFPatelJDillonRVijayPBrownALDistinct evolution and dynamics of epigenetic and genetic heterogeneity in acute myeloid leukemia22792799201610.1038/nm.4125273227444938719AbboshCBirkbakNJWilsonGAJamal-HanjaniMConstantinTSalariRLe QuesneJMooreDAVeeriahSRosenthalRTRACERx consortiumPEACE consortium: Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution545446451201710.1038/nature2236428445469TammelaTSanchez-RiveraFJCetinbasNMWuKJoshiNSHeleniusKParkYAzimiRKerperNRWesselhoeftRAA Wnt-producing niche drives proliferative potential and progression in lung adenocarcinoma545355359201710.1038/nature2233428489818WeisSMChereshDATumor angiogenesis: Molecular pathways and therapeutic targets1713591370201110.1038/nm.253722064426MaoYKellerETGarfieldDHShenKWangJStromal cells in tumor microenvironment and breast cancer32303315201310.1007/s10555-012-9415-3SonBLeeSYounHKimEKimWYounBThe role of tumor microenvironment in therapeutic resistance83933394520175354804AndersonKGStromnesIMGreenbergPDObstacles posed by the tumor microenvironment to T cell activity: A case for synergistic therapies31311325201710.1016/j.ccell.2017.02.008282924355423788WangZLiuPInuzukaHWeiWRoles of F-box proteins in cancer14233247201410.1038/nrc3700246582744306233KatohMHiraiMSugimuraTTeradaMCloning, expression and chromosomal localization of Wnt-13, a novel member of the Wnt gene family1387387619968761309KatohMKirikoshiHTerasakiHShiokawaKWNT2B2 mRNA, up-regulated in primary gastric cancer, is a positive regulator of the WNT-β-catenin-TCF signaling pathway28910931098200110.1006/bbrc.2001.607611741304JiangHLiFHeCWangXLiQGaoHExpression of Gli1 and Wnt2B correlates with progression and clinical outcome of pancreatic cancer7453145382014251208494129084SteinhartZPavlovicZChandrashekharMHartTWangXZhangXRobitailleMBrownKRJaksaniSOvermeerRGenome-wide CRISPR screens reveal a Wnt-FZD5 signaling circuit as a druggable vulnerability of RNF43-mutant pancreatic tumors236068201710.1038/nm.4219SeshagiriSStawiskiEWDurinckSModrusanZStormEEConboyCBChaudhuriSGuanYJanakiramanVJaiswalBSRecurrent R-spondin fusions in colon cancer488660664201210.1038/nature11282228951933690621KinzlerKWVogelsteinBLessons from hereditary colorectal cancer87159170199610.1016/S0092-8674(00)81333-18861899MazzoniSMFearonERAXIN1 and AXIN2 variants in gastrointestinal cancers35518201410.1016/j.canlet.2014.09.018252369104298141ChicheAMoumenMRomagnoliMPetitVLaslaHJézéquelPde la GrangePJonkersJDeugnierMAGlukhovaMAp53 deficiency induces cancer stem cell pool expansion in a mouse model of triple-negative breast tumors3623552365201710.1038/onc.2016.396ValentiGQuinnHMHeynenGJJELanLHollandJDVogelRWulf-GoldenbergABirchmeierWCancer stem cells regulate cancer-associated fibroblasts via activation of Hedgehog signaling in mammary gland tumors7721342147201710.1158/0008-5472.CAN-15-349028202523KatohMWNT/PCP signaling pathway and human cancer (Review)1415831588200516273260YangYMlodzikMWnt-Frizzled/planar cell polarity signaling: Cellular orientation by facing the wind (Wnt)31623646201510.1146/annurev-cellbio-100814-125315265661184673888MinegishiKHashimotoMAjimaRTakaokaKShinoharaKIkawaYNishimuraHMcMahonAPWillertKOkadaYA Wnt5 activity asymmetry and intercellular signaling via PCP proteins polarize node cells for left-right symmetry breaking40439452.e4201710.1016/j.devcel.2017.02.01028292423WuJMlodzikMWnt/PCP instructions for cilia in left-right asymmetry40423424201710.1016/j.devcel.2017.02.023282924195490791WangWRunkleKBTerkowskiSMEkairebRIWitzeESProtein depalmitoylation is induced by Wnt5a and promotes polarized cell behavior2901570715716201510.1074/jbc.M115.639609259449114505481NishimuraTHondaHTakeichiMPlanar cell polarity links axes of spatial dynamics in neural-tube closure14910841097201210.1016/j.cell.2012.04.02122632972De MarcoPMerelloEPiatelliGCamaAKibarZCapraVPlanar cell polarity gene mutations contribute to the etiology of human neural tube defects in our population100633641201410.1002/bdra.2325524838524GöddeNJPearsonHBSmithLKHumbertPODissecting the role of polarity regulators in cancer through the use of mouse models328249257201410.1016/j.yexcr.2014.08.03625179759JohnsonRHalderGThe two faces of Hippo: Targeting the Hippo pathway for regenerative medicine and cancer treatment136379201410.1038/nrd41614167640ZhangSChenLCuiBChuangHYYuJWang-RodriguezJTangLChenGBasakGWKippsTJROR1 is expressed in human breast cancer and associated with enhanced tumor-cell growth7e31127201210.1371/journal.pone.0031127224036103293865AnastasJNKulikauskasRMTamirTRizosHLongGVvon EuwEMYangPTChenHWHayduLToroniRAWNT5A enhances resistance of melanoma cells to targeted BRAF inhibitors12428772890201410.1172/JCI70156248654254071371YuJChenLCuiBWidhopfGFIIShenZWuRZhangLZhangSBriggsSPKippsTJWnt5a induces ROR1/ROR2 heterooligomerization to enhance leukemia chemotaxis and proliferation126585598201610.1172/JCI835354731190GreenJLKuntzSGSternbergPWRor receptor tyrosine kinases: Orphans no more18536544200810.1016/j.tcb.2008.08.006188487784672995LuWYamamotoVOrtegaBBaltimoreDMammalian Ryk is a Wnt coreceptor required for stimulation of neurite outgrowth11997108200410.1016/j.cell.2004.09.01915454084PetrovaIMMalessyMJVerhaagenJFradkinLGNoordermeerJNWnt signaling through the Ror receptor in the nervous system49303315201410.1007/s12035-013-8520-9DebebeZRathmellWKRor2 as a therapeutic target in cancer150143148201510.1016/j.pharmthera.2015.01.01025614331BicoccaVTChangBHMasoulehBKMuschenMLoriauxMMDrukerBJTynerJWCrosstalk between ROR1 and the Pre-B cell receptor promotes survival of t(1;19) acute lymphoblastic leukemia22656667201210.1016/j.ccr.2012.08.027231535383500515Hojjat-FarsangiMMoshfeghADaneshmaneshAHKhanASMikaelssonEOsterborgAMellstedtHThe receptor tyrosine kinase ROR1 - an oncofetal antigen for targeted cancer therapy292131201410.1016/j.semcancer.2014.07.00525068995GentileALazzariLBenvenutiSTrusolinoLComoglioPMThe ROR1 pseudokinase diversifies signaling outputs in MET-addicted cancer cells13523052316201410.1002/ijc.2887924706440YamaguchiTLuCIdaLYanagisawaKUsukuraJChengJHottaNShimadaYIsomuraHSuzukiMROR1 sustains caveolae and survival signalling as a scaffold of cavin-1 and caveolin-1710060201610.1038/ncomms10060267259824777216LiCWangSXingZLinALiangKSongJHuQYaoJChenZParkPKA ROR1-HER3-lncRNA signalling axis modulates the Hippo-YAP pathway to regulate bone metastasis19106119201710.1038/ncb3464281142695336186DijksterhuisJPPetersenJSchulteGWNT/Frizzled signalling: receptor-ligand selectivity with focus on FZD-G protein signalling and its physiological relevance: IUPHAR Review 317111951209201410.1111/bph.123643952798ZhanTRindtorffNBoutrosMWnt signaling in cancer3614611473201710.1038/onc.2016.3045357762GongBShenWXiaoWMengYMengAJiaSThe Sec14-like phosphatidylinositol transfer proteins Sec14l3/SEC14L2 act as GTPase proteins to mediate Wnt/Ca(2+) signaling6e26362201710.7554/eLife.26362KimSNieHNesinVTranUOutedaPBaiCXKeelingJMaskeyDWatnickTWesselyOThe polycystin complex mediates Wnt/Ca(2+) signalling187527642016272142814925210IshitaniTKishidaSHyodo-MiuraJUenoNYasudaJWatermanMShibuyaHMoonRTNinomiya-TsujiJMatsumotoKThe TAK1-NLK mitogen-activated protein kinase cascade functions in the Wnt-5a/Ca(2+) pathway to antagonize Wnt/β-catenin signaling23131139200310.1128/MCB.23.1.131-139.2003140665ZhangMHagenmuellerMRiffelJHKreusserMMBernholdEFanJKatusHABacksJHardtSECalcium/calmodulin-dependent protein kinase II couples Wnt signaling with histone deacetylase 4 and mediates dishevelled-induced cardiomyopathy65335344201510.1161/HYPERTENSIONAHA.114.04467ScholzBKornCWojtarowiczJMoglerCAugustinIBoutrosMNiehrsCAugustinHGEndothelial RSPO3 controls vascular stability and pruning through non-canonical WNT/Ca(2+)/NFAT signaling367993201610.1016/j.devcel.2015.12.01526766444WangWSnyderNWorthAJBlairIAWitzeESRegulation of lipid synthesis by the RNA helicase Mov10 controls Wnt5a production4e154201510.1038/oncsis.2015.15260298284753523MiyamotoDTZhengYWittnerBSLeeRJZhuHBroderickKTDesaiRFoxDBBranniganBWTrautweinJRNA-Seq of single prostate CTCs implicates noncanonical Wnt signaling in antiandrogen resistance34913511356201510.1126/science.aab0917263839554872391BlumenthalAEhlersSLauberJBuerJLangeCGoldmannTHeineHBrandtEReilingNThe Wingless homolog WNT5A and its receptor Frizzled-5 regulate inflammatory responses of human mononuclear cells induced by microbial stimulation108965973200610.1182/blood-2005-12-504616601243WangLSteeleIKumarJDDimalineRJitheshPVTiszlaviczLReiszZDockrayGJVarroADistinct miRNA profiles in normal and gastric cancer myofibroblasts and significance in Wnt signaling310G696G704201610.1152/ajpgi.00443.2015269398694867324AznarNMiddeKKDunkelYLopez-SanchezIPavlovaYMarivinABarbazánJMurrayFNitscheUJanssenKPDaple is a novel non-receptor GEF required for trimeric G protein activation in Wnt signaling4e07091201510.7554/eLife.07091261262664484057YuFXZhaoBGuanKLHippo pathway in organ size control, tissue homeostasis, and cancer163811828201510.1016/j.cell.2015.10.044265449354638384HansenCGMoroishiTGuanKLYAP and TAZ: A nexus for Hippo signaling and beyond25499513201510.1016/j.tcb.2015.05.002260452584554827HotBValnohovaJArthoferESimonKShinJUhlénMKostenisEMulderJSchulteGFZD10-Gα13 signalling axis points to a role of FZD10 in CNS angiogenesis3293103201710.1016/j.cellsig.2017.01.02328126591TakebeNMieleLHarrisPJJeongWBandoHKahnMYangSXIvySPTargeting Notch, Hedgehog, and Wnt pathways in cancer stem cells: Clinical update12445464201510.1038/nrclinonc.2015.61258505534520755KahnMWnt signaling in stem cells and tumor stem cells33317325201510.1055/s-0035-155840426251120TaiDWellsKArcaroliJVanderbiltCAisnerDLMessersmithWALieuCHTargeting the WNT signaling pathway in cancer therapeutics2011891198201510.1634/theoncologist.2015-0057263069034591954GurneyAAxelrodFBondCJCainJChartierCDoniganLFischerMChaudhariAJiMKapounAMWnt pathway inhibition via the targeting of Frizzled receptors results in decreased growth and tumorigenicity of human tumors1091171711722201210.1073/pnas.1120068109227534653406803NielsenTOPoulinNMLadanyiMSynovial sarcoma: Recent discoveries as a roadmap to new avenues for therapy5124134201510.1158/2159-8290.CD-14-1246256144894320664GongXAzhdariniaAGhoshSCXiongWAnZLiuQCarmonKSLGR5-targeted antibody-drug conjugate eradicates gastrointestinal tumors and prevents recurrence1515801590201610.1158/1535-7163.MCT-16-011427207778DamelinMBankovichABernsteinJLucasJChenLWilliamsSParkAAguilarJErnstoffECharatiMA PTK7-targeted antibody-drug conjugate reduces tumorinitiating cells and induces sustained tumor regressions9pii: eaag2611201710.1126/scitranslmed.aag2611ZhangSCuiBLaiHLiuGGhiaEMWidhopfGFIIZhangZWuCCChenLWuROvarian cancer stem cells express ROR1, which can be targeted for anti-cancer-stem-cell therapy1111726617271201410.1073/pnas.1419599111254113174260559StormEEDurinckSde Sousa e MeloFTremayneJKljavinNTanCYeXChiuCPhamTHongoJATargeting PTPRK-RSPO3 colon tumours promotes differentiation and loss of stem-cell function52997100201610.1038/nature16466BergerCSommermeyerDHudecekMBergerMBalakrishnanAPaszkiewiczPJKosasihPLRaderCRiddellSRSafety of targeting ROR1 in primates with chimeric antigen receptor-modified T cells3206216201510.1158/2326-6066.CIR-14-01634324006LePNMcDermottJDJimenoATargeting the Wnt pathway in human cancers: Therapeutic targeting with a focus on OMP-54F28146111201510.1016/j.pharmthera.2014.08.005ChengYPhoonYPJinXChongSYIpJCWongBWLungMLWnt-C59 arrests stemness and suppresses growth of nasopharyngeal carcinoma in mice by inhibiting the Wnt pathway in the tumor microenvironment61442814439201510.18632/oncotarget.3982259805014546477PoulsenAHoSYWangWAlamJJeyarajDAAngSHTanESLinGRCheongVWKeZPharmacophore model for Wnt/Porcupine inhibitors and its use in drug design5514351448201510.1021/acs.jcim.5b0015926024410LangtonPFKakugawaSVincentJPMaking, exporting, and modulating Wnts26756765201610.1016/j.tcb.2016.05.01127325141DeBruineZJKeJHarikumarKGGuXBorowskyPWilliamsBOXuWMillerLJXuHEMelcherKWnt5a promotes Frizzled-4 signalosome assembly by stabilizing cysteine-rich domain dimerization31916926201710.1101/gad.298331.117285465125458758MadanBKeZHarmstonNHoSYFroisAOAlamJJeyarajDAPendharkarVGhoshKVirshupIHWnt addiction of genetically defined cancers reversed by PORCN inhibition3521972207201610.1038/onc.2015.280ChenBDodgeMETangWLuJMaZFanCWWeiSHaoWKilgoreJWilliamsNSSmall molecule-mediated disruption of Wnt-dependent signaling in tissue regeneration and cancer5100107200910.1038/nchembio.137191251562628455ProffittKDMadanBKeZPendharkarVDingLLeeMAHannoushRNVirshupDMPharmacological inhibition of the Wnt acyltransferase PORCN prevents growth of WNT-driven mammary cancer73502507201310.1158/0008-5472.CAN-12-2258AgarwalPZhangBHoYCookALiLMikhailFMWangYMcLaughlinMEBhatiaREnhanced targeting of CML stem and progenitor cells by inhibition of porcupine acyltrans-ferase in combination with TKI12910081020201710.1182/blood-2016-05-714089LiuCYuXADP-ribosyltransferases and poly ADP-ribosylation16491501201510.2174/1389203716666150504122435259382424725697KulakOChenHHolohanBWuXHeHBorekDOtwinowskiZYamaguchiKGarofaloLAMaZDisruption of Wnt/β-catenin signaling and telomeric shortening are inextricable consequences of tankyrase inhibition in human cells3524252435201510.1128/MCB.00392-15259393834475917WangWLiNLiXTranMKHanXChenJTankyrase inhibitors target YAP by stabilizing Angiomotin family proteins13524532201510.1016/j.celrep.2015.09.014264568204618173NathubhaiAHaikarainenTKoivunenJMurthySKoumanovFLloydMDHolmanGDPihlajaniemiTToshDLehtiöLHighly potent and isoform selective dual site binding Tankyrase/Wnt signaling inhibitors that increase cellular glucose uptake and have antiproliferative activity60814820201710.1021/acs.jmedchem.6b01574QuackenbushKSBagbySTaiWMMessersmithWASchreiberAGreeneJKimJWangGPurkeyAPittsTMThe novel tankyrase inhibitor (AZ1366) enhances irinotecan activity in tumors that exhibit elevated tankyrase and irinotecan resistance72827328285201610.18632/oncotarget.8626270700885053726LauTChanECallowMWaalerJBoggsJBlakeRAMagnusonSSambroneASchuttenMFiresteinRA novel tankyrase small-molecule inhibitor suppresses APC mutation-driven colorectal tumor growth7331323144201310.1158/0008-5472.CAN-12-456223539443WaalerJMachonOTumovaLDinhHKorinekVWilsonSRPaulsenJEPedersenNMEideTJMachonovaOA novel tankyrase inhibitor decreases canonical Wnt signaling in colon carcinoma cells and reduces tumor growth in conditional APC mutant mice7228222832201210.1158/0008-5472.CAN-11-333622440753ArquésOChicoteIPuigITenbaumSPArgilésGDienstmannRFernándezNCaratùGMatitoJSilberschmidtDTankyrase inhibition blocks Wnt/β-catenin pathway and reverts resistance to PI3K and AKT inhibitors in the treatment of colorectal cancer22644656201610.1158/1078-0432.CCR-14-3081HuangSMMishinaYMLiuSCheungAStegmeierFMichaudGACharlatOWielletteEZhangYWiessnerSTankyrase inhibition stabilizes axin and antagonizes Wnt signalling461614620200910.1038/nature0835619759537SchoumacherMHurovKELehárJYan-NealeYMishinaYSonkinDKornJMFlemmingDJonesMDAntonakosBInhibiting Tankyrases sensitizes KRAS-mutant cancer cells to MEK inhibitors via FGFR2 feedback signaling7432943305201410.1158/0008-5472.CAN-14-0138-T24747911WangHLuBCastilloJZhangYYangZMcAllisterGLindemanAReece-HoyesJTallaricoJRussCTankyrase inhibitor sensitizes lung cancer cells to endothelial growth factor receptor (EGFR) inhibition via stabilizing angiomotins and inhibiting YAP signaling2911525615266201610.1074/jbc.M116.722967272313414946938ScarboroughHAHelfrichBACasás-SelvesMSchullerAGGrosskurthSEKimJTanACChanDCZhangZZaberezhnyyVAZ1366: An inhibitor of tankyrase and the canonical Wnt pathway that limits the persistence of non-small cell lung cancer cells following EGFR inhibition2315311541201710.1158/1078-0432.CCR-16-1179Pelay-GimenoMGlasAKochOGrossmannTNStructure-based design of inhibitors of protein-protein interactions: Mimicking peptide binding epitopes5488968927201510.1002/anie.201412070261199254557054HwangSYDengXByunSLeeCLeeSJSuhHZhangJKangQZhangTWestoverKDDirect targeting of β-catenin by a small molecule stimulates proteasomal degradation and suppresses oncogenic Wnt/β-catenin signaling162836201610.1016/j.celrep.2016.05.071273209234957947MahmoudiTLiVSNgSSTaouatasNVriesRGMohammedSHeckAJCleversHThe kinase TNIK is an essential activator of Wnt target genes2833293340200910.1038/emboj.2009.285198164032776109LeeYJungJIParkKYKimSAKimJSynergistic inhibition effect of TNIK inhibitor KY-05009 and receptor tyrosine kinase inhibitor dovitinib on IL-6-induced proliferation and Wnt signaling pathway in human multiple myeloma cells841091411012017284677975522218TanZChenLZhangSComprehensive modeling and discovery of mebendazole as a novel TRAF2- and NCK-interacting kinase inhibitor633534201610.1038/srep33534276501685030704FiskusWSharmaSSahaSShahBDevarajSGSunBHorriganSLevequeCZuYIyerSPre-clinical efficacy of combined therapy with novel β-catenin antagonist BC2059 and histone deacetylase inhibitor against AML cells2912671278201510.1038/leu.2014.340TrautmannMSieversEAretzSKindlerDMichelsSFriedrichsNRennerMKirfelJSteinerSHussSSS18-SSX fusion protein-induced Wnt/β-catenin signaling is a therapeutic target in synovial sarcoma3350065016201410.1038/onc.2013.443KimJYLeeHYParkKKChoiYKNamJSHongISCWP232228 targets liver cancer stem cells through Wnt/β-catenin signaling: A novel therapeutic approach for liver cancer treatment72039520409201610.18632/oncotarget.7954269672484991463NagarajABJosephPKovalenkoOSinghSArmstrongARedlineRResnickKZanottiKWaggonerSDiFeoACritical role of Wnt/β-catenin signaling in driving epithelial ovarian cancer platinum resistance62372023734201510.18632/oncotarget.4690261254414695147FangLZhuQNeuenschwanderMSpeckerEWulf-GoldenbergAWeisWIvon KriesJPBirchmeierWA small-molecule antagonist of the β-catenin/TCF4 interaction blocks the self-renewal of cancer stem cells and suppresses tumorigenesis76891901201610.1158/0008-5472.CAN-15-1519SukhdeoKManiMZhangYDuttaJYasuiHRooneyMDCarrascoDEZhengMHeHTaiYTTargeting the β-catenin/TCF transcriptional complex in the treatment of multiple myeloma10475167521200710.1073/pnas.0610299104ZhouHMakPYMuHMakDHZengZCortesJLiuQAndreeffMCarterBZCombined inhibition of β-catenin and Bcr-Abl synergistically targets tyrosine kinase inhibitor-resistant blast crisis chronic myeloid leukemia blasts and progenitors in vitro and in vivoApr182017Epub ahead of print10.1038/leu.2017.87TakadaKZhuDBirdGHSukhdeoKZhaoJJManiMLemieuxMCarrascoDERyanJHorstDTargeted disruption of the BCL9/β-catenin complex inhibits oncogenic Wnt signaling4148ra117201210.1126/scitranslmed.3003808WangQAmatoSPRubitskiDMHaywardMMKormosBLVerhoestPRXuLBrandonNJEhlersMDIdentification of phosphorylation consensus sequences and endogenous neuronal substrates of the psychiatric risk kinase TNIK356410423201610.1124/jpet.115.229880ColucciaAMVaccaADuñachMMologniLRedaelliSBustosVHBenatiDPinnaLAGambacorti-PasseriniCBcr-Abl stabilizes β-catenin in chronic myeloid leukemia through its tyrosine phosphorylation2614561466200710.1038/sj.emboj.7601485173181911817619NakayamaSSngNCarreteroJWelnerRHayashiYYamamotoMTanAJYamaguchiNYasudaHLiDβ-catenin contributes to lung tumor development induced by EGFR mutations7458915902201410.1158/0008-5472.CAN-14-0184251640104199914KajiguchiTKatsumiATanizakiRKiyoiHNaoeTY654 of β-catenin is essential for FLT3/ITD-related tyrosine phosphorylation and nuclear localization of β-catenin88314320201210.1111/j.1600-0609.2011.01738.xJinBDingKPanJPonatinib induces apoptosis in imatinib-resistant human mast cells by dephosphorylating mutant D816V KIT and silencing β-catenin signaling1312171230201410.1158/1535-7163.MCT-13-039724552773Fernández-SánchezMEBarbierSWhiteheadJBéalleGMichelALatorre-OssaHReyCFouassierLClaperonABrulléLMechanical induction of the tumorigenic β-catenin pathway by tumour growth pressure5239295201510.1038/nature14329ZhaoYMasielloDMcMillianMNguyenCWuYMelendezESmbatyanGKidaAHeYTeoJLCBP/catenin antagonist safely eliminates drug-resistant leukemiainitiating cells3537053717201610.1038/onc.2015.438SmythMJNgiowSFRibasATengMWCombination cancer immunotherapies tailored to the tumour microenvironment13143158201610.1038/nrclinonc.2015.209PaluckaAKCoussensLMThe basis of oncoimmunology16412331247201610.1016/j.cell.2016.01.049269672894788788ZarourHMReversing T-cell dysfunction and exhaustion in cancer2218561864201610.1158/1078-0432.CCR-15-1849270847394872712ChenDSMellmanIElements of cancer immunity and the cancer-immune set point541321330201710.1038/nature2134928102259InmanBALongoTARamalingamSHarrisonMRAtezolizumab: A PD-L1-blocking antibody for bladder cancer2318861890201710.1158/1078-0432.CCR-16-1417KimESAvelumab: First global approval77929937201710.1007/s40265-017-0749-628456944SyedYYDurvalumab: First global approval7713691376201710.1007/s40265-017-0782-528643244ZaretskyJMGarcia-DiazAShinDSEscuin-OrdinasHHugoWHu-LieskovanSTorrejonDYAbril-RodriguezGSandovalSBarthlyLMutations associated with acquired resistance to PD-1 blockade in melanoma375819829201610.1056/NEJMoa1604958274338435007206ShinDSZaretskyJMEscuin-OrdinasHGarcia-DiazAHu-LieskovanSKalbasiAGrassoCSHugoWSandovalSTorrejonDYPrimary resistance to PD-1 blockade mediated by JAK1/2 mutations7188201201710.1158/2159-8290.CD-16-1223AnagnostouVSmithKNFordePMNiknafsNBhattacharyaRWhiteJZhangTAdleffVPhallenJWaliNEvolution of neoantigen landscape during immune checkpoint blockade in non-small cell lung cancer7264276201710.1158/2159-8290.CD-16-0828HuangACPostowMAOrlowskiRJMickRBengschBManneSXuWHarmonSGilesJRWenzBT-cell invigoration to tumour burden ratio associated with anti-PD-1 response5456065201710.1038/nature22079283978215554367MangusoRTPopeHWZimmerMDBrownFDYatesKBMillerBCCollinsNBBiKLaFleurMWJunejaVRIn vivo CRISPR screening identifies Ptpn2 as a cancer immunotherapy target547413418201710.1038/nature2327028723893HoltzhausenAZhaoFEvansKSTsutsuiMOrabonaCTylerDSHanksBAMelanoma-derived Wnt5a promotes local dendritic-cell expression of IDO and immunotolerance: Opportunities for pharmacologic enhancement of immunotherapy310821095201510.1158/2326-6066.CIR-14-0167260417364927300HugoWZaretskyJMSunLSongCMorenoBHHu-LieskovanSBerent-MaozBPangJChmielowskiBCherryGGenomic and transcriptomic features of response to anti-PD-1 therapy in metastatic melanoma1653544201610.1016/j.cell.2016.02.065269974804808437D'AmicoLMahajanSCapiettoAHYangZZamaniARicciBBumpassDBMeyerMSuXWang-GillamADickkopf-related protein 1 (Dkk1) regulates the accumulation and function of myeloid derived suppressor cells in cancer213827840201610.1084/jem.20150950270450064854727FulcinitiMTassonePHideshimaTValletSNanjappaPEttenbergSAShenZPatelNTaiYTChauhanDAnti-DKK1 mAb (BHQ880) as a potential therapeutic agent for multiple myeloma114371379200910.1182/blood-2008-11-191577194172132714212BendellJCMurphyJEMahalingamDHalmosBSirardCALandauSBRyanDPA Phase 1 study of DKN-01, an anti-DKK1 antibody, in combination with paclitaxel in patients with DKK1 relapsed or refractory esophageal cancer or gastro-esophageal junction tumors34Suppl 4S1112016http://ascopubs.org/doi/abs/10.1200/jco.2016.34.4_suppl.11110.1200/jco.2016.34.4_suppl.111CamidgeDRPaoWSequistLVAcquired resistance to TKIs in solid tumours: Learning from lung cancer11473481201410.1038/nrclinonc.2014.10424981256PauliCHopkinsBDPrandiDShawRFedrizziTSbonerASailerVAugelloMPucaLRosatiRPersonalized in vitro and in vivo cancer models to guide precision medicine7462477201710.1158/2159-8290.CD-16-1154283310025413423MassardCMichielsSFertéCLe DeleyMCLacroixLHollebecqueAVerlingueLIleanaERoselliniSAmmariSHigh-throughput genomics and clinical outcome in hard-to-treat advanced cancers: Results of the MOSCATO 01 trial7586595201710.1158/2159-8290.CD-16-139628365644RheinbayEParasuramanPGrimsbyJTiaoGEngreitzJMKimJLawrenceMSTaylor-WeinerARodriguez-CuevasSRosenbergMRecurrent and functional regulatory mutations in breast cancer5475560201710.1038/nature22992286582085563978van de WeteringMFranciesHEFrancisJMBounovaGIorioFPronkAvan HoudtWvan GorpJTaylor-WeinerAKesterLProspective derivation of a living organoid biobank of colorectal cancer patients161933945201510.1016/j.cell.2015.03.05325957691MerkerSRWeitzJStangeDEGastrointestinal organoids: How they gut it out420239250201610.1016/j.ydbio.2016.08.01027521455ZhangLAdilehMMartinMLKlinglerSWhiteJMaXHoweLRBrownAMKolesnickREstablishing estrogen-responsive mouse mammary organoids from single Lgr5(+) cells294151201710.1016/j.cellsig.2016.08.001
Therapeutic resistance owing to evolution and plasticity of cancer stem cells (CSCs). CSCs with self-renewal, differentiation and de-differentiation potentials undergo omics reprogramming, such as epigenetic reprogramming, immunoediting (immunological reprogramming), two-way shifts between epithelial and mesenchymal states (epithelial-mesenchymal reprogramming) and two-way shifts between aerobic glycolysis and oxidative phosphorylation in the tricarboxylic acid cycle (metabolic reprogramming). Genetic or epigenetic evolution of CSCs gives rise to a repertoire of drug-resistant CSCs, which cause early recurrence through clonal expansion of drug-resistant CSCs replacing drug-sensitive bulk tumors. By contrast, the plasticity of CSCs with omics reprogramming potential gives rise to dormant CSCs to survive host defense or therapeutic insult, which cause late relapse through reactivation of dormant CSCs into cycling CSCs. CSC-targeted therapeutics are necessary to avoid drug resistance or recurrence after anticancer therapy. MDSC, myeloid-derived suppressor cell; NK, natural killer cell; Treg, regulatory T cell.
Overview of WNT signaling cascades and WNT signaling-targeted therapeutics. WNT signals are transduced by multiple downstream signaling cascades in a cell context-dependent manner. Canonical WNT signaling through Frizzled (FZD) and LRP5/6 receptors is transduced by the WNT/β-catenin and WNT/STOP (stabilization of proteins) signaling cascades, whereas non-canonical WNT signaling through FZD and/or ROR1/ROR2/RYK receptors is transduced by the WNT/PCP (planar cell polarity), WNT/RTK (receptor tyrosine kinase) and WNT/Ca2+ signaling cascades. Antibody-based drugs, such as anti-LGR5 antibody-drug conjugate (ADC), anti-RSPO3 monoclonal antibody (mAb), anti-ROR1 mAb and anti-PTK7 ADC, ROR1 chimeric antigen receptor-modified T (CAR-T) cells, porcupine (PORCN) inhibitors and β-catenin inhibitors are representative WNT signaling-targeted therapeutics in clinical trials or preclinical studies for the treatment of cancer patients.
Investigational WNT signaling-targeted therapeutics for genome-based precision medicine. WNT signaling-targeted therapeutics are applicable for mono-therapy of WNT-related human cancers: β-catenin inhibitors for WNT-driven cancers with APC or CTNNB1 alterations; porcupine (PORCN) inhibitors, anti-FZD or anti-RSPO3 monoclonal antibody (mAb) for WNT-driven cancers with RNF43, RSPO2, RSPO3 or ZNRF3 alterations; and anti-ROR1 mAb for WNT-driven cancers with ROR1 upregulation. By contrast, WNT signaling-targeted therapeutics are applicable for combination therapies with tyrosine kinase inhibitors (TKI) to treat a subset of tyrosine kinase (TK)-driven cancers. WNT signaling-targeted therapeutics are also applicable for combination therapies with immune checkpoint blockers (ICB) to treat cancers with immune evasion; however, because WNT signals regulate immune evasion and antitumor immunity in a context-dependent manner, monitoring of WNT signaling and immunity is mandatory to select an appropriate class of WNT signaling-targeted therapeutics for combination immunotherapy. Therefore, omics monitoring, including genome sequencing, transcriptomic, immunohistochemical and organoid-based tests, is necessary before and during selection of WNT signaling-targeted therapeutics for cancer patients. Mut, mutation; Fus, fusion.