AML is categorized into subtypes based on genetic and transcriptomic characteristics, one of which is defined by the homeobox (HOX) gene upregulation and primarily includes NPM1-mutant (NPM1-mut) and MLL-rearranged leukemia (22). MLL proteins (MLL1 and MLL2) belong to the histone H3 position 4 lysine (H3K4) methyltransferase family, which is essential for the maintenance of high HOX gene expression, and activate myeloid ecotropic viral integration site 1 (MEIS1) through direct epigenetic regulation (16). Notably, MLL fusion proteins contain specific Su(var)3-9, Enhancer-of-zeste, Trithorax) structural domains, whereas the crystal structure of menin proteins exhibits a rectangular conformation, which allows for the formation of deep binding pockets that bind specifically to the N-terminal fragment of MLL fusion proteins (23,24). This interaction designates menin protein as an oncogenic cofactor that facilitates histone H3 lysine trimethylation at position 4 (H3K4me3) via its engagement with MLL, subsequently enhancing HOX/MEIS1 gene expression and precipitating leukemia (25). Utilizing a structure-based drug design approach targeting the menin-MLL interaction interface, Krivtsov et al (15) developed a highly selective small molecule inhibitor, VTP50469, which displaces menin from the fusion protein and prevents the recruitment of MLL to target genes. Both cell and animal studies (immunodeficient NSG mice xenotransplanted with human KMT2A-r leukemia cells) have demonstrated notable anti-leukemic efficacy (15,26). While preclinical data indicate that the small molecule inhibitors exhibit potential anti-leukemic efficacy, the extensive menin-MLL binding interface reveals that the crystal structure of VTP50469 occupies a subregion of the menin-MLL interface (15,27). This indicates the necessity for potentially higher inhibitor concentrations to achieve complete menin-MLL disruption, consistent with the typical dose-response association of partial protein-protein interaction inhibitors (28,29). This technical barrier may represent a notable impediment in the translation of menin-MLL-targeted therapies from laboratory research to clinical application.

The sirtuin family comprises seven highly conserved members (SIRT1-SIRT7) that share evolutionary conservation, all of which possess highly conserved catalytic structural domains, differing markedly only at their N- and C-terminus (30,31). This structure enables each member to exhibit NAD⁺-dependent deacetylase and ADP-ribosyltransferase activity (31). As components of histone deacetylases, SIRTs serve a key role in cell proliferation, survival, maintenance of genomic stability and metabolic regulation by modulating gene expression and chromatin dynamics. A direct interaction between the menin protein and SIRT1 has been identified (30). Menin binds directly to the deacetylase structural domain of SIRT1 through its C-terminal domain, which forms a functional complex that regulates epigenetic processes. In mouse hepatocytes, SIRT1 modulates CD36 gene expression and intracellular triglyceride accumulation via histone deacetylation, a process that is contingent upon the involvement of the menin protein (32). Furthermore, in hepatocellular carcinoma cells, menin enhances NF-κB (p65) deacetylation by recruiting SIRT1, which underscores its key role in the SIRT regulatory network (33). Numerous studies have demonstrated that SIRT1 impacts apoptosis and inflammatory activation by modulating the NF-κB pathway (34–36). For example, in murine models, upregulation of SIRT1 promotes B lymphocyte proliferation, inhibits apoptosis and advances inflammatory responses by suppressing the NF-κB pathway (37,38). Therefore, it is hypothesized that in acute leukemia, the menin-SIRT interaction may also influence apoptosis and inflammatory activation via the NF-κB pathway, potentially inhibiting or promoting acute leukemia (39).

The human genome encodes a total of 11 PRMTs, which regulate cell signaling networks by modifying arginine residues in both histone and non-histone proteins (40). As important epigenetic regulators in eukaryotes, all members of the PRMT family contain highly conserved S-adenosylmethionine (SAM)-dependent methyltransferase structural domains that facilitate the transfer of methyl groups from SAM to the nitrogen atom of substrate arginine residues (41,42). Menin protein can recruit PRMT5 to the growth arrest-specific protein 1 (GAS1) gene locus, inhibiting GAS1 gene expression by promoting the symmetric dimethylation of histone H4 at position 3 (H4R3me2) (43). However, in MLL, the interaction between menin protein and PRMT5 leads to decreased levels of H4R3me2 and fails to effectively inhibit GAS1 expression (44,45). This suggests that the regulation of PRMT by menin protein may be context-dependent (43). In MEN1 tumor syndrome and mixed-lineage leukemia (MLL), the regulation of GAS1 by the menin-PRMT5 complex exhibits opposite outcomes, suggesting an oncogenic isoform of the menin-PRMT5 complex that reverses epigenetic manifestations by altering the conformation of the complex (43,44).

SUV39H1 is a histone H3 lysine 9 methyltransferase (H3K9). Menin protein enhances trimethylation of H3K9 in the promoter regions of target genes by interacting with SUV39H1, thereby silencing transcription of associated genes (24,46). In a previous study on IL-6 gene regulation, Song et al (47) detected the enrichment of menin protein and SUV39H1 around the IL-6 gene using chromatin immunoprecipitation (ChIP). The aforementioned study reported that menin protein and SUV39H1 are specifically recruited to the auxiliary region of the IL-6 promoter and the recruitment of SUV39H1 decreases with the depletion of menin protein, which suggests menin protein may serve a key role in the regulation of SUV39H1. Further analysis indicated that menin protein and SUV39H1 may regulate IL-6 gene expression at the protein level through H3K9 methylation (47). Numerous preclinical and clinical studies have confirmed that IL-6 serves a notable role in the development of acute leukemia (48–50). Anti-IL-6 antibodies, such as cetuximab, have potential therapeutic value in the treatment of various malignancies, including acute leukemia, either alone or in combination with chemotherapy regimens (51). However, the pathogenesis of leukemia involves a complex regulatory network of multiple signaling pathways - such as JAK/STAT, NF-κB and Wnt/β-catenin - which limits the therapeutic efficacy of targeting IL-6 alone (52–54). Following blocking IL-6 signaling, leukemia cells sustain their survival and proliferative capacity by activating alternative pathways (for example, Janus kinase/STAT), which markedly reduces the clinical benefit of single-agent therapy. These direct epigenetic regulatory interactions mediated by menin are summarized in Table I.

Agarwalet al (18) demonstrated, via a yeast two-hybrid assay using a galactose-responsive transcription factor 4 (Gal4) DNA-binding domain fusion of full-length menin protein, that JunD, a member of the activator protein 1 family, interacts with menin protein. This interaction is contingent upon the structural domains located at the N-terminal end of menin protein. The aforementioned study identified the N-terminal region of JunD binding to menin protein as the menin binding sequence (JunDMBL). Notably, although the binding modes of JunDMBL and the MLL binding sequence exhibit similarities, they exert opposite effects on transcriptional regulation (55). Menin-JunD complexes may interfere with JNK-mediated phosphorylation of JunD and c-Jun, thereby inhibiting the Ras signaling pathway (56,57). However, the specific target genes regulated by the menin-JunD complex remain unclear and further research is warranted to explore its potential application in leukemia treatment (55).

SMAD proteins are key downstream effector molecules in the TGF-β signaling pathway and serve a direct role in TGF-β signaling and gene transcriptional regulation (58). As transcriptional regulators, menin protein binds SMAD proteins, thereby indirectly influencing the activity of the TGF-β signaling pathway and regulating the transcription of target genes. In pituitary secretory tumor cell lines, menin protein markedly enhances the binding specificity of SMAD3 to DNA sequences via interaction with SMAD3 (59,60). More importantly, during osteoblast differentiation and maturation, menin protein forms complexes with SMAD1, SMAD5 and the key regulator of osteogenesis Runt-related transcription factor 2 to promote the differentiation of mesenchymal stem cells into osteoblasts (59,61). While the interaction of menin protein with SMAD1, SMAD3 and SMAD5 has been demonstrated (59), the specific molecular mechanisms underlying their synergistic activation of transcription warrant further investigation.

As a key proto-oncogene, the dysregulated expression of Myc is closely associated with >50% of malignant tumorigenesis (62). Myc serves primarily as a transcription factor through the classical enhancer-box (E-box) region (63). Wu et al (64) demonstrated that Myc forms a regulatory complex with positive transcription elongation factor b (P-TEEb) within the E-box region to activate transcription, with the menin protein being a key factor in this process. Menin regulates Myc-mediated transcriptional activity by influencing the transcriptional elongation regulator P-TEEb. In the KMT2A rearrangement (KMT2A-r) AML model, the expression of Myc and its characteristic genes is markedly suppressed in leukemia cells following treatment with a menin inhibitor (65). Zhou et al (65) found a notable positive correlation between menin protein levels and Myc expression, which suggests Myc may serve as a common target of menin protein. Based on these findings, co-targeting menin protein and Myc may represent a novel therapeutic strategy for leukemia treatment in future.

The FOX family is an evolutionarily conserved group of transcription factors, all of which possess the distinctive forkhead DNA-binding structural domain and are key for cell proliferation and differentiation (66). Previous studies have indicated that menin protein engages with several members of the FOX family, such as FOXG1, FOXA1 and FOXO1 (67–69). In FOXG1-associated encephalopathy, menin protein influences α-thalassemia X-linked mental retardation protein-mediated FOXG1 transcription via modulation of the FOXG1 transcripts (67). Bonnavion et al (70) established that menin protein interacts with FOXA2, which influences its trans-auto reactivation ability and serves a role in the control of FOXA2 expression in adult pancreatic α-cells.

The inaugural member of the Wnt family was identified in 1982 and research has consistently validated the essential function of the Wnt/β-catenin signaling pathway in embryonic development and tissue regeneration (71–73), Dysregulation of this system results in numerous illnesses, such as colorectal and gastric cancer (74–77). Menin protein serves as a reciprocal partner of β-catenin proteins, the principal effector molecules of this signaling pathway, and can facilitate their nuclear translocation. ChIP and chromosome conformation capture (3C) studies demonstrated that the menin protein augments the association of β-catenin proteins with the Myc promoter (78–80). The mechanism of action of menin protein inhibitors in the treatment of AML may partially arise from their suppression of the Wnt/β-catenin protein signaling pathway (81–83).

Nuclear receptors are a class of receptor proteins located in the nucleus, which include the androgen receptor (AR), estrogen, thyroid hormone, glucocorticoid, retinoid X, peroxisome proliferator-activated, liver X and retinoic acid receptors (84). These receptors not only serve as biosensors to regulate key cellular activities such as proliferation, differentiation, and apoptosis but also directly bind to DNA to exert transcriptional regulation (85,86). The interactions between nuclear receptors and tumor growth have attracted notable research regarding their role in tumor progression (87–89). Luo et al (90) identified that the menin protein exhibits distinct pro-oncogenic actions in androgen receptor-dependent prostate cancer cells by modulating AR transcription and its target genes. Based on the presence of nuclear receptor interaction sites in the amino acid sequence of the menin protein, menin serves as an important coactivator of nuclear receptor-mediated transcription (68,90).

The NF-κB family comprises five members: Rel or c-Rel, RelA or p65, RelB, NF-κB1 or p50 and NF-κB2 or p52. Each member exists in dimeric form and possesses a Rel homology domain (91). The pro-carcinogenic role of NF-κB is prevalent in hepatocellular carcinoma (92). Previous studies have demonstrated that menin protein engages with NF-κB and suppresses p65-mediated transcriptional activation via the recruitment of SIRT1 (33,93). Another previous study revealed that the degree of menin-NF-κB interaction changes the production of cell cycle protein D1, a downstream signaling molecule of NF-κB that governs the G1/S phase transition and affects cell proliferation (55). Irregularities in this mechanism may result in tumorigenesis.

Patients with acute leukemia characterized by KMT2A-r, previously referred to as MLL, exhibit a long-term survival rate <60% and poor prognosis across all age demographics (100,101). This leukemia variant exhibits a high prevalence among infants and children, accounting for >70% of new acute lymphoblastic leukemia (ALL) diagnoses in infants, is marked by notable aggressiveness, frequent relapse, substantial medication resistance and presents considerable challenges for therapeutic management as a high-risk genetic subtype (101).

KMT2A-r may lead to aberrant expression of the HOX gene and its DNA-binding cofactor MEIS1, which may inhibit hematological development and precipitate leukemia (21,102). Although no specific medications have been approved for KMT2A-r leukemia, preclinical studies have identified the chromatin regulatory protein menin as a promising therapeutic target (14,103,104). In KMT2A-driven leukemia, all KMT2A fusion proteins contain menin-binding sequences, with menin protein serving as a key cofactor that facilitates the interaction between the KMT2A protein complex and the HOX gene promoter. In a study using the KMT2A-mut leukemia model (105), it was demonstrated that the inhibition of menin protein markedly reduces the transcript levels of HOX and MEIS1, thereby reversing the leukemogenesis process.

Through the examination of gene expression in pediatric and adult patients with primary AML, researchers discovered that NPM1-mut leukemia exhibits notable similarities to the KMT2A-r subtype and NPM1 is associated with the HOX/MEIS1 gene cluster (106). NPM1-mut is among the most prevalent genetic alterations in AML, affecting ~30% of the total patient population (107). These mutations, primarily located in the terminal exons of the NPM1 gene, enhance nuclear export signaling activity and impair nucleolus localization signaling, which results in the dysregulated expression of the HOXA/B and MEIS1 genes (108). NPM1 may serve as a transcriptional amplifier of gene expression, potentially constituting a notable factor in the development of AML (109). Dillon et al (110) identified microscopic residual lesions in patients with AML through pre-transplantation DNA sequencing of hematopoietic stem cells, which revealed that patients with NPM1-mut AML experience a significantly higher recurrence rate and shorter survival compared with those without NPM1-mut.

The persistence of NPM1-mut AML in an undifferentiated state is attributed to the HOX-associated pathway, which underscores the therapeutic potential of targeting this pathway. Menin protein serves as a cofactor to promote H3K4me3 through interactions with MLL, thereby modulating the expression of HOX and MEIS1 genes. This mechanism highlights the feasibility of targeting menin protein for therapeutic interventions (96). In vivo experiments have demonstrated that inhibitors of menin protein exhibit notable anti-leukemic activity in NPM1-mut leukemia (20,21,111). Previous studies conducted in NPM1-mutant leukemia models have indicated that treatment with the menin inhibitor VTP50469, a precursor drug to revumenib, leads to downregulation of oncogenic cofactors such as MEIS1 and a marked reduction in the self-renewal capacity of leukemic stem cells (15,104).