International Journal of Molecular Medicine is an international journal devoted to molecular mechanisms of human disease.
International Journal of Oncology is an international journal devoted to oncology research and cancer treatment.
Covers molecular medicine topics such as pharmacology, pathology, genetics, neuroscience, infectious diseases, molecular cardiology, and molecular surgery.
Oncology Reports is an international journal devoted to fundamental and applied research in Oncology.
Experimental and Therapeutic Medicine is an international journal devoted to laboratory and clinical medicine.
Oncology Letters is an international journal devoted to Experimental and Clinical Oncology.
Explores a wide range of biological and medical fields, including pharmacology, genetics, microbiology, neuroscience, and molecular cardiology.
International journal addressing all aspects of oncology research, from tumorigenesis and oncogenes to chemotherapy and metastasis.
Multidisciplinary open-access journal spanning biochemistry, genetics, neuroscience, environmental health, and synthetic biology.
Open-access journal combining biochemistry, pharmacology, immunology, and genetics to advance health through functional nutrition.
Publishes open-access research on using epigenetics to advance understanding and treatment of human disease.
An International Open Access Journal Devoted to General Medicine.
Cysteinyl leukotriene receptor antagonists (LTRAs), currently used for the treatment of asthma and allergic rhinitis, demonstrate anticancer effects in in vitro and in vivo models (1,2). Overexpression of 5-lipoxygenase, a leukotriene synthesis enzyme, and leukotriene receptors are found in numerous types of cancer, including breast cancer (BC) (3). A large population study in Taiwanese patients with asthma using LTRAs identified a decreased risk of breast, lung, colorectal and liver cancer compared with non-LTRA users (4). In this study, a hazard ratio of LTRA users was 0.31 and the increase of cumulative dose progressively decreased cancer risk. Two subsequent large retrospective cohort studies also reported a lower risk of cancers in asthmatic patients taking LTRAs. Korean patients showed significant lower risk of cancers after taking high dose of LTRAs (adjusted HR=0.56) or 3 years or more of LTRA use (adjusted HR=0.68 after 3 years and 0.33 after 5 years) (5). In Japanese patients, the high accumulative dose of LTRAs was associated with a decrease in risk of cancer (adjusted HR=0.57) (6). Cysteinyl leukotriene receptor 1 (CysLT1R), a receptor of leukotriene D4, is highly expressed in breast tumor tissues compared with in normal breast tissues, and its expression is greater in higher grade tumors (3). MDA-MB-231, a triple-negative BC (TNBC) cell line, expresses CysLT1R but not CysLT2R (3). Our previous study reported the apoptotic and antiproliferative effects of two LTRAs, montelukast and zafirlukast, on MDA-MB-231 cells (7). In addition, LTRAs have been reported to induce the apoptosis of glioblastoma and lung cancer cells by reducing ERK1/2 phosphorylation and Bcl-2 levels (8,9). Zafirlukast has also been shown to induce G0/G1 cell cycle arrest by upregulating p53 and p21 expression in both glioblastoma A172 and U-87 MG cells, and p27 expression in U-87 MG cells (10). Similarly, only zafirlukast can induce G0/G1 cell cycle arrest in MDA-MB-231 cells (7). However, the mechanisms underlying the cytotoxic and antiproliferative effects of LTRAs on MDA-MB-231 cells remain unknown. The present study aimed to compare the effects of montelukast and zafirlukast on the molecular mechanisms regulating proliferation and death in MDA-MB-231 cells.
MDA-MB-231 cells (cat. no. HTB-26) were obtained from American Type Culture Collection and cultured in DMEM (cat. no. 12800-017) supplemented with 1% penicillin/streptomycin (cat. no. 15140) and 10% fetal bovine serum (cat. no. 10270) (all Gibco; Thermo Fisher Scientific, Inc.). Cells were maintained at 37°C in a humidified atmosphere containing 5% CO2.
Montelukast (cat. no. SML0101) and zafirlukast (cat. no. Z4152) were purchased from Sigma-Aldrich (Merck KGaA), and were dissolved in DMSO (cat. no. D4540; Sigma-Aldrich; Merck KGaA). GSK2606414 (cat. no. HY-18072) was purchased from MedChemExpress. The final concentration of DMSO was 0.04% (v/v) in culture media, as previously described (7).
Cells were treated with DMSO, montelukast at 20 µM, or zafirlukast at 20 µM at 37°C for 3 h in reverse transcription-quantitative PCR analysis, 6, 12 or 48 h in western blotting, and 6 or 12 h in flow cytometric analysis and apoptosis assay. GSK2606414 was treated 1 h prior to the addition of montelukast or zafirlukast.
Cells were transfected with 50 nM ON-TARGETplus siRNA Human DNA damage-inducible transcript 3 (DDIT3, also known as C/EBP homologous protein or CHOP) SMARTpool (cat. no. L-004819-00-0005) or ON-TARGETplus Non-targeting Control Pool (cat. no. D-001810-10-05; both GE Healthcare Dharmacon, Inc.; Table I). All four siRNAs were mixed in the same reaction. DharmaFECT 4 Transfection Reagent (cat. no. T-2004-02; GE Healthcare Dharmacon, Inc.) was used according to the manufacturer's instructions. Cells were transfected at 37°C for 48 h for gene expression studies and for 96 h before determining protein expression. Cells were immediately treat with DMSO, montelukast at 20 µM, or zafirlukast at 20 µM for 12 h.
Proteins were harvested from cells and detected as previously described (10). Protein concentrations were determined by Bradford Protein Assay (cat. no. 5000006; Bio-Rad) and 25 µg protein were loaded into each lane. Nitrocellulose membranes were blocked with 5% non-fat dry milk (cat. no. 1706404; Bio-Rad) in 0.5% TBS-T at 4°C overnight and probed with primary antibodies against phosphorylated (p)-ERK1/2 (rabbit; 1:4,000; cat. no. 4370), ERK1/2 (rabbit; 1:2,000; cat. no. 4695), Bcl-2 (rabbit; 1:600; cat. no. 4223), PARP-1 (rabbit; 1:2,000; cat. no. 9542), LC3-A/B (rabbit; 1:1,000; cat. no. 12741), activating transcription factor 6 (ATF6; rabbit; 1:1,000; cat. no. 65880), CHOP (mouse; 1:1,000; cat. no. 2895), p21 (rabbit; 1:1,000; cat. no. 2947), p27 (rabbit; 1:1,000; cat. no. 3686), CDK4 (rabbit; 1:1,000; cat. no. 12790), cyclin D1 (rabbit; 1:1,000; cat. no. 2978) (all Cell Signaling Technology, Inc.) and cyclin E (mouse; 1:1,000; cat. no. 05-363; Merck KGaA) for 2 h at room temperature. β-actin (rabbit; 1:10,000; cat. no. 4970) and β-tubulin (mouse; 1:5,000; cat. no. 86298) (both Cell Signaling Technology, Inc.) were incubated for 45 min at room temperature. After that, membranes were incubated with anti-rabbit or anti-mouse conjugated with horseradish peroxidase enzymes for 1 h at room temperature (goat; 1:4,000; cat. no. 111-035-003 or 115-035-003; Jackson ImmunoResearch Laboratories). Bands were visualized using Clarity Western ECL substrate (cat. no. 1705061; Bio-Rad) and quantified using ImageJ software (version 1.54; National Institutes of Health and the Laboratory for Optical and Computational Instrumentation). β-actin or β-tubulin was used as loading controls depending on the molecular weight of proteins of interest. The band intensity was normalized to the expression of the loading control.
Cells were detached with 0.05% trypsin-EDTA (cat. no. 25300054; Gibco; Thermo Fisher Scientific, Inc.) at 37°C for 2 min and centrifuged at 320 × g for 10 min at room temperature. The levels of monomeric JC-1, caspase 3/7 activity, autophagic LC3, p-ATM and p-histone H2AX (H2AX) were measured using Guava Mitochondrial Depolarization Kit, Guava® Caspase 3/7 FAM Kit (cat. no. 4500-0540; Merck Millipore; Merck KGaA), FlowCellect Histone H2AX Phosphorylation Assay Kit (cat. no. FCCS100182; Merck Millipore; Merck KGaA), phycoerythrin-conjugated anti-p-ATM (Ser1981) (cat. no. FCMAB110P; Merck Millipore; Merck KGaA) and FlowCellect™ Autophagy LC3 Antibody-based Assay Kit (cat. no. FCCH100171; Merck Millipore; Merck KGaA), respectively. All tests were performed according to the manufacturer's protocol. The percentage of dead cells was determined by 7-aminoactinomycin D (7-AAD) staining when assessing mitochondrial depolarization. Cells were assessed using the Guava® easyCyte 5HT benchtop flow cytometer with InCyte 3.1 (both Cytek Biosciences). A minimum of 2,000 events was analyzed for each sample.
Total RNA from cells was extracted using the Total RNA Mini kit (cat. no. RB300; Geneaid Biotech Ltd.) according to the manufacturer's protocol. cDNA synthesis and qPCR were performed using superscript III reverse transcriptase (cat. no. 18080-044; Invitrogen; Thermo Fisher Scientific, Inc.) and SensiFAST SYBR Lo-ROX (cat. no. BIO-94005; Bioline; Meridian Bioscience) on an Applied Biosystems Real-time PCR 7500 system (Applied Biosystems; Thermo Fisher Scientific, Inc.) as previously described (11). All primers are listed in Table II. The thermocycling conditions were as follows: Initial denaturation at 50°C for 2 min and 95°C for 10 min, followed by 40 cycles at 95°C for 15 sec and 58°C for 1 min, with a melting curve stage of 95°C for 10 sec and 60°C for 1 min. The Cq value of each target gene was normalized to the expression of GAPDH. Relative fold-change was calculated against untreated cells based on the 2−ΔΔCq method (12).
Floating cells and cells detached with 0.05% trypsin-EDTA were collected and centrifuged at 320 × g for 10 min at room temperature. Pellets were washed twice in Annexin V binding buffer, and were then with Annexin V-FITC (cat. no. 556419) and 7-AAD (cat. no. 51-68981E) (both BD Biosciences). The percentage of Annexin V positive cells representing early and late apoptotic cells was determined using a BD Accuri C6 Plus with BD Accuri C6 Plus Software version 1.0.1 (both BD Biosciences). A minimum of 5,000 events/sample were collected.
Cells were seeded in 96-well clear bottom black plates and incubated with 20 µM DCFH diacetate (cat. no. D6883; Sigma-Aldrich; Merck KGaA) in phenol red-free MEM (cat. no. 12800-017; Sigma-Aldrich; Merck KGaA) in the dark before being treated with DMSO, montelukast at 20 µM, or zafirlukast at 20 µM for 3 h. The DCF fluorescence intensity was detected using a Varioskan™ Flash spectral scanning Multimode Reader (Thermo Fisher Scientific, Inc.) with 490/535 nm excitation/emission wavelengths. The DCF fluorescence intensity of each treatment was normalized to fluorescence intensity of untreated cells.
Data are presented as the mean ± SEM (n≥3). Data were analyzed by one- or two-way ANOVA followed by Tukey's post hoc test using GraphPad Prism version 5.0 (Dotmatics). The level of significance was defined as P<0.05.
Although both montelukast and zafirlukast at 20 µM have been reported to inhibit MDA-MB-231 cell proliferation, only 20 µM zafirlukast can induce G0/G1 cell cycle arrest at 48 h post-exposure, according to a previous study (7). Therefore, the effects of both drugs on the expression of two proliferating markers, Ki-67 and proliferating cell nuclear antigen (PCNA), were assessed. Montelukast and zafirlukast at 20 µM decreased Ki-67 and PCNA at 6 h post-exposure (Fig. 1A and B). Cells were treated with 20 µM drugs for 48 h and the expression levels of proteins regulating cell cycle progression were determined using western blotting. Cyclin D1 and CDK4 levels were decreased in cells that were treated with zafirlukast (Fig. 1C and D), while both drugs had no effect on cyclin E levels (Fig. S1). Zafirlukast significantly decreased p21 expression, whereas the increase of p21 by montelukast was not significant (Fig. 1E). Increased p27 expression was found only in cells treated with zafirlukast (Fig. 1F).
Montelukast at ≥10 µM and zafirlukast at 20 µM were previously reported to induce the apoptosis of MDA-MB-231 cells at 24 h post-exposure (7); therefore, 20 µM was used to assess cell death in the present study. The expression levels of p-ERK1/2 and Bcl-2 were detected using western blotting. Montelukast and zafirlukast decreased the expression levels of p-ERK1/2 at 6 h (Fig. 2A and B) and the anti-apoptotic protein Bcl-2 at 12 h post-exposure (Fig. 2A and C). Both LTRAs did not alter levels of ERK1/2 (Fig. 2A and B). Next, cells were stained with JC-1 and 7-AAD to assess mitochondrial membrane potential and cell death, respectively. Both LTRAs increased the levels of cells with green fluorescent signal, indicative of monomeric JC-1, at 12 h post-exposure (Fig. 2D and E). The levels of 7-AAD-positive cells after being exposed to montelukast and zafirlukast were 48.98±7.22 and 31.61±2.04%, respectively, compared with 3.97±0.50% in DMSO-treated cells at 12 h (data not shown). Caspase 3/7 activity was also measured by flow cytometry. Both drugs increased caspase 3/7 activity at 12 h post-treatment, with a greater effect observed in montelukast-treated cells (Fig. 2F and G)
To test whether autophagy was caused by LTRAs, LC3 levels were measured by western blotting and flow cytometry. Montelukast and zafirlukast did not alter LC3-I levels at 6 h post-exposure, while zafirlukast decreased LC3-I levels at 12 h post-exposure (Fig. 3A and B). Both drugs elevated LC3-II levels at 6 and 12 h post-treatment (Fig. 3A and C). The expression of lipidated LC3 sequestered into autophagosomes was determined by using flow cytometry. Both drugs caused a rightward shift of autophagic LC3 fluorescence intensity and increased the mean fluorescent intensity of autophagic LC3 at 12 h post-exposure (Fig. 3D and E).
Apoptosis and autophagy are triggered in response to DNA damage (13). The levels of PARP-1, a key regulator of the DNA repair process, were measured by western blotting in the present study. Montelukast and zafirlukast increased levels of 89-kDa fragments of PARP-1 at 6 and 12 h after treatment (Fig. 4A and B). Cells with positive staining of p-ATM and p-H2AX, two DNA damage markers, were counted by flow cytometry at 12 h post-exposure. Montelukast and zafirlukast increased p-ATM and p-H2AX levels (Fig. 4C-E). Montelukast showed significantly higher p-ATM levels than zafirlukast.
Activation of ER stress can lead to either autophagy or apoptotic cell death (14,15). In the present study, the expression of ER membrane-associated sensors and signaling molecules was evaluated using RT-qPCR at 6 h post-treatment. Montelukast, but not zafirlukast, upregulated the expression levels of PERK and ATF4 (Fig. 5A and B). Both montelukast and zafirlukast increased the mRNA expression levels of X-box binding protein 1 splice variant (XBP-1s), CHOP and growth arrest and DNA damage-inducible gene 34 (GADD34), but had no effect on ATF6 mRNA levels (Fig. 5C-F). The protein expression levels of CHOP in montelukast-treated cells were significantly higher than those in zafirlukast-treated cells (Fig. 5G and H). The activation of ER stress triggers cleavage of ATF6 (16). Montelukast and zafirlukast decreased the expression levels of total ATF6 protein (Fig. 5G), and the cleaved ATF6/ATF6 level in zafirlukast-treated cells was greater than that in montelukast-treated cells (Fig. 5I). The cleaved ATF6/ATF6 levels at 12 h post-zafirlukast treatment were higher than those at 6 h.
To determine the contribution of ER stress to LTRA-induced apoptotic cell death, GSK2606414, a PERK inhibitor, and siRNA targeting CHOP) were used. The percentage of cells with Annexin V staining was measured at 12 h post-exposure to LTRAs. Montelukast and zafirlukast increased the percentage of Annexin V-positive cells; however, pre-treatment with GSK2606414 only decreased the percentage of montelukast-induced Annexin V-positive cells (Fig. 6). CHOP siRNA decreased the CHOP mRNA levels to 14% compared to non-targeting control siRNA (Fig. 7A). The mRNA expression levels of CHOP triggered by montelukast were decreased to 23% at 48 h post-transfection with CHOP siRNA compared with cells with non-targeting control siRNA (Fig. 7A). By contrast, the downregulation of Ki-67 and PCNA by montelukast was not reversed by CHOP siRNA (Fig. 7B and C). Transfection with CHOP siRNA resulted in lower levels of Annexin V-positive cells than in the group transfected with the non-targeting control siRNA following exposure to montelukast or zafirlukast (Fig. 7D and E).
To examine whether LTRAs induced oxidative stress, intracellular reactive oxygen species and the expression of antioxidant enzymes were measured using DCF assays and RT-qPCR, respectively. Montelukast and zafirlukast at 20 µM did not increase DCF fluorescent intensity compared with DMSO at 1 and 3 h post-treatment (Fig. 8A). Both drugs decreased the expression of catalase, glutathione reductase and glutathione S-transferase at 6 h post-exposure to montelukast and zafirlukast; however, neither drug affected the expression of superoxide dismutase and glutathione peroxidase (Fig. 8B-F).
Our previous findings showed that LTRAs, including montelukast and zafirlukast, have the potential for BC treatment by inhibiting cancer progression and inducing apoptosis in the absence of hormonal stimuli (7). The apoptotic effects of montelukast are more potent than zafirlukast in TNBC MDA-MB-231 cells. Zafirlukast induces cell cycle arrest at G0/G1 phase, while montelukast treatment does not induce cell cycle arrest at a specific phase and preferentially induced cell death (7). The present study demonstrated that montelukast and zafirlukast differentially mediated CysLT1R signaling in MDA-MB-231 cells. Montelukast and zafirlukast activates two ER stress sensors: ATF6 and IRE1; but only montelukast triggers PERK. The accumulation of zafirlukast-treated cells in G0/G1 phase as previously report (7) is mediated by the upregulation of p27, and the decrease of CDK4 and cyclin D1. Montelukast exhibited a greater effect than zafirlukast on the upregulation of caspase 3/7, DNA damage and CHOP. Montelukast activated all three pathways of ER stress: PERK, ATF6, and IRE1; while zafirlukast only triggered the cleavage of ATF6 and XBP-1. Both LTRAs also triggered autophagic response and decreased the expression of antioxidant enzymes.
A key feature of cancer is the loss of cell cycle regulation. Cell cycle arrest is the primary mechanism controlling the proliferation of cancer cells and cell death (17). Ki-67 is a prognostic biomarker of BC and was used in the recent American Joint Committee on Cancer Staging System for BC (18,19). In the present study, both LTRAs significantly decreased the expression of two cell proliferating markers, Ki-67 and PCNA, in MDA-MB-231 cells. The present results are consistent with a previous study that showed inhibition of proliferation of non-tumor and tumor-derived intestinal epithelial cells by LTRAs (20).
The upregulation of cyclin D1 promotes progression of cells in the G1 phase while cyclin E is a key regulator for cells to enter S phase. Cyclin D1 forms complexes with CDK4 or CDK6 to trigger phosphorylation of retinoblastoma protein (Rb), leading to the release of Rb from transcription factor E2F. E2F then induces the synthesis of cyclin E and cyclin A, which regulate the S phase (21). In the present study, zafirlukast decreased the expression of cyclin D1 and CDK4 but showed no effect on cyclin E expression. This suggested that the potential G0/G1 cell cycle arrest was mediated by the reduction of cyclin D1/CDK4 complexes. In addition to cyclin D1, length of the G1 phase is regulated by the CDK inhibitor p27. The inhibitory effect of p27 is key for entry into S phase because p27 blocks the activity of cyclin E/CDK2, an initiator of DNA synthesis. The inhibition of p27 expression decreases the length of the G1 phase, and cyclin D1 inhibits the activity of p27 (22). Therefore, the G0/G1 cell cycle arrest induced by zafirlukast in MDA-MB-231 cells in our previous study (7) may be mediated by the combination of cyclin D1 downregulation and p27 upregulation. On the other hand, decreased CDK4 expression without altered expression of cyclin D1, cyclin E and p27 could explain the decrease of cell proliferation without cell cycle arrest at specific phases induced by montelukast. Our previous study showed that zafirlukast can increase the levels of p53, p21 and p27 in U-87 MG glioblastoma cells (10). In the present study, zafirlukast decreased p21 expression. U-87 MG expresses wild-type p53, while p53 in MDA-MB-231 is mutated (23). Although the most well-known function of p21 is as a cell cycle inhibitor protein, there are reports of p21 having oncogenic effects (24,25).
To date, three CDK 4/6 inhibitor agents (palbociclib, ribociclib and abemaciclib) have been approved by the Food and Drug Administration of United States and are available for patients with BC. The major side effect of these CDK 4/6 inhibitors is bone marrow suppression, resulting in anemia, neutropenia and thrombocytopenia (26). LTRAs are generally considered safe and well-tolerated drugs because of their mild side effects (1,27). With the growing evidence of anticancer effects and the inhibition of CDK4/6, LTRAs could be repurposed as a chemopreventive agent or adjuvant in BC therapy. In the present study, zafirlukast reduced the expression of both cyclin D1 and CDK4; therefore, this drug may be a better candidate than montelukast as a cyclin-CDK inhibitor. However, studies have reported neuropsychiatric effects, such as depression, hallucination and suicidal ideation, related to the use of montelukast and zafirlukast (28,29).
The regulation of Bcl-2 by decreasing ERK1/2 activation following LTRA treatment has been reported in glioblastoma (10), lung cancer (9), leukemia (30) and colorectal cancer (31). In the present study, decreased expression of p-ERK1/2 in the cells treated with LTRAs was observed before a time-dependent reduction of Bcl-2 expression. Therefore, LTRA-induced Bcl-2 downregulation in MDA-MB-231 cells is potentially mediated by the inhibition of ERK1/2 phosphorylation. The activation of the ERK1/2 pathway triggers the degradation of p27 (22). Therefore, the upregulation of p27 observed in the present study could be mediated by inhibition of ERK1/2 phosphorylation. Bcl-2 expression maintains the integrity of the mitochondrial outer membrane and prevents the release of cytochrome c and caspase activation (32). In healthy cells, JC-1 dye enters and forms aggregates with orange fluorescent signals. The decrease of JC-1 aggregation by LTRAs indicated a loss of mitochondrial membrane potential. Both LTRAs also increased levels of caspase 3/7-positive cells, indicating that LTRAs enhanced cell death via the intrinsic mitochondrial apoptotic pathway in MDA-MB-231 cells. The increase of caspase-3 activation by montelukast is consistent with previous studies in colon cancer (33) and leukemia (30).
Caspase-mediated apoptotic cell death is accomplished via cleavage of several key proteins, including PARP-1. Cleavage of PARP-1 by caspases, a hallmark of apoptosis, decreases DNA-binding capacity, which disrupts the routine repair of DNA damage. Bcl-2 is an upstream regulator of PARP-1 activation (34). Decreased Bcl-2 levels and the upregulation of caspase 3/7 may lead to the increase of cleaved-PARP-1 by LTRAs in MDA-MB-231 cells. This is consistent with previous findings in chronic myeloid leukemia, which revealed that montelukast triggers the mitochondrial apoptosis pathway by increasing the activities of cytochrome c, caspase-3 and cleavage of PARP-1 (20,30). The inhibition of PARP-1 can increase ATM activation and promote H2AX phosphorylation (13). The elevation of cleaved-PARP-1, p-ATM and p-H2AX by LTRAs in the present study indicated DNA damage in MDA-MB-231 cells.
Autophagy serves a protective role in cancer cells during chemotherapy, allowing cancer cells to alleviate cellular stress, causing drug resistance. However, a number of cytotoxic drugs promote cancer cell death via autophagy (35). The present study showed the increased cleavage of LC3 (LC3-II), a marker of autophagy, and decreased LC3-I in MDA-MB cells following LTRA treatment, suggesting that the inhibition of leukotriene signaling could induce autophagy. This observation aligns with the increase in LC3-II induced by LTRAs in retinal pigment epithelial cells and a rat model of hemorrhagic cystitis (36,37).
ER stress serves a dual role in cell survival and death via apoptosis or autophagy in BC cells (14,15). In the present study, the induction of key effectors involved in ER stress and/or unfolded protein response (UPR) signaling by both LTRAs was evidenced by an increase in ER stress markers, including CHOP and XBP-1s, as well as the reduction of ATF6 due to proteolytic cleavage. CHOP is a key link between the UPR and pro-apoptotic activation (38). The PERK/eukaryotic translation initiation factor 2α/ATF4 pathway plays an important role in the upregulation of CHOP in cancer cells (39). Activation of IRE1 induces the splicing of XBP-1 mRNA. XBP-1s and cleaved-ATF6 also trigger CHOP expression (38). In the present study, the higher levels of CHOP induced by montelukast compared with zafirlukast are likely caused by the activation of all three ER stress sensors: PERK, ATF6, and IRE1. In contrast, zafirlukast did not upregulate the PERK/ATF4 pathway. GADD34 is one of the downstream transcriptional targets of CHOP. This protein acts as a part of negative feedback loop for the response essential for cell survival by prolonged CHOP expression (40). In the present study, both LTRAs triggered the expression of CHOP and GADD34.
CHOP is a key protein responsible for ER stress-induced cell death by downregulating Bcl-2 (41). CHOP activates caspase-3 and PARP-1 (42), and induces the expression of autophagy-related genes (38). In BC, the increased expression of CHOP indicates ER stress-induced autophagic cell death (14,15). In the present study, the downregulation of CHOP by siRNA decreased LTRA-induced apoptosis. Montelukast upregulated PERK and the inhibition of PERK using its specific inhibitor reduced montelukast-induced apoptosis. These results suggested that the upregulation of ER stress contributed to LTRA-induced cell death. The expression of CHOP has been shown to be associated with a lower risk of recurrence and prolonged disease-free survival in patients with BC (43). Therefore, the increase of CHOP expression by LTRAs could be an important mechanism for BC treatment. Upregulation of CHOP could lead to cell cycle arrest. Although the downregulation of CHOP via siRNA did not alter the decrease the expression levels of the proliferating markers Ki-67 and PCNA in MDA-MB-231 cells, further studies on CHOP knockdown and cell proliferation are of interest in other types of cancers to investigate the role of ER stress in the inhibition of cell proliferation.
Excessive oxidative stress leads to cell death. Antioxidants and olaparib, a PARP-1 inhibitor, have been shown to decrease zafirlukast-induced cell death in renal cell carcinoma (44). In the present study, montelukast and zafirlukast decreased the expression of antioxidant enzymes including catalase, glutathione S-transferase and glutathione reductase. Montelukast exhibits protective effects against oxidative and ER stress in non-cancerous models (45–48). Montelukast can ameliorate acetaminophen-induced liver injury and methotrexate-induced kidney damage by decreasing oxidative stress (45,46). Montelukast has also been shown to decrease the expression of ER stress markers, including CHOP, GADD34, ATF4 and IRE1a, in models of hepatotoxicity and diabetes (47,48). These differential effects require further studies in other cancerous cells.
The toxic concentrations of LTRAs required for anticancer effects are greater than plasma concentrations used in asthma treatment. Pharmacokinetic studies of a single dose of 10 mg montelukast and 20 mg zafirlukast detected 0.63 µM of montelukast and 0.58 µM of zafirlukast in human plasma (49,50). Novel localized drug delivery using polymeric wafers, nanofibrous scaffolds and hydrogels could increase drug concentrations at cancer sites (51). It is also possible to use nanocarriers to deliver LTRAs via intraductal delivery (52). Graphine oxide nanoparticles of montelukast have been shown to increase apoptosis of inflammatory cells in a mouse asthma model (53). The volume of distribution of montelukast and zafirlukast is ~10 and 70 l, respectively (49,54). The greater the volume of distribution, the greater the tissue accumulation. Zafirlukast, with a higher volume of distribution and effects on both cell cycle arrest and apoptosis, could be a better candidate than montelukast. The anti-inflammatory effects of LTRAs for capsular contracture after breast augmentation have suggested a potential role for these drugs in BC treatment (55,56). Zafirlukast has been shown to prevent the metastasis of MDA-MB-231 cells to the bone and lung by blocking CysLT1R on platelets, subsequently inhibiting platelet aggregation and adhesion on cancer cells (57). In addition, Montelukast may suppress the epithelial-mesenchymal transition in MDA-MB-231 cells (58). The knockdown of CysLT1R using siRNA or CRISPR may confirm the role of this receptor in cell death pathways.
In conclusion, LTRAs effectively inhibited MDA-MB-231 cells via multiple downstream signaling pathways, including induction of cell cycle arrest, apoptosis, autophagy, DNA damage and ER stress. The use of one cell line is a limitation of this study. The different effects on cell death and proliferation induced by montelukast and zafirlukast should be further investigated in other BC cells and animal models.
Not applicable.
The present study was supported by the Faculty of Medicine Ramathibodi Hospital, Mahidol University (grant no. RF_64093).
The data generated in the present study may be requested from the corresponding author.
PV, NS and PW conceived the study. PV, TS and SP analyzed data and wrote the manuscript. PV, KK and TS collected data. PV and TS confirm the authenticity of all the raw data. PV and TS edited the manuscript. All authors have read and approved the final manuscript.
Not applicable.
Not applicable.
The authors declare that they have no competing interests.
|
Riccioni G, Bucciarelli T, Mancini B, Di Ilio C and D'Orazio N: Antileukotriene drugs: clinical application, effectiveness and safety. Curr Med Chem. 14:1966–1977. 2007. View Article : Google Scholar : PubMed/NCBI | |
|
Tsai MJ, Chang WA, Chuang CH, Wu KL, Cheng CH, Sheu CC, Hsu YL and Hung JY: Cysteinyl leukotriene pathway and cancer. Int J Mol Sci. 23:1202021. View Article : Google Scholar : PubMed/NCBI | |
|
Magnusson C, Liu J, Ehrnstrom R, Manjer J, Jirström K, Andersson T and Sjölander A: Cysteinyl leukotriene receptor expression pattern affects migration of breast cancer cells and survival of breast cancer patients. Int J Cancer. 129:9–22. 2011. View Article : Google Scholar : PubMed/NCBI | |
|
Tsai MJ, Wu PH, Sheu CC, Hsu YL, Chang WA, Hung JY, Yang CJ, Yang YH, Kuo PL and Huang MS: cysteinyl leukotriene receptor antagonists decrease cancer risk in asthma patients. Sci Rep. 6:239792016. View Article : Google Scholar : PubMed/NCBI | |
|
Jang HY, Kim IW and Oh JM: Cysteinyl leukotriene receptor antagonists associated with a decreased incidence of cancer: A retrospective cohort study. Front Oncol. 12:8588552022. View Article : Google Scholar : PubMed/NCBI | |
|
Maeda-Minami A, Hosokawa M, Ishikura Y, Onoda A, Kawano Y, Negishi K, Shimada S, Ihara T, Sugamata M, Takeda K and Mano Y: Relationship between leukotriene receptor antagonists on cancer development in patients with bronchial asthma: A retrospective analysis. Anticancer Res. 42:3717–3724. 2022. View Article : Google Scholar : PubMed/NCBI | |
|
Suknuntha K, Yubolphan R, Krueaprasertkul K, Srihirun S, Sibmooh N and Vivithanaporn P: Leukotriene receptor antagonists inhibit mitogenic activity in triple negative breast cancer cells. Asian Pac J Cancer Prev. 19:833–837. 2018.PubMed/NCBI | |
|
Piromkraipak P, Sangpairoj K, Tirakotai W, Chaithirayanon K, Unchern S, Supavilai P, Power C and Vivithanaporn P: Cysteinyl leukotriene receptor antagonists inhibit migration, invasion, and expression of MMP-2/9 in human glioblastoma. Cell Mol Neurobiol. 38:559–573. 2018. View Article : Google Scholar : PubMed/NCBI | |
|
Tsai MJ, Chang WA, Tsai PH, Wu CY, Ho YW, Yen MC, Lin YS, Kuo PL and Hsu YL: Montelukast induces apoptosis-inducing factor-mediated cell death of lung cancer cells. Int J Mol Sci. 18:13532017. View Article : Google Scholar : PubMed/NCBI | |
|
Piromkraipak P, Parakaw T, Phuagkhaopong S, Srihirun S, Chongthammakun S, Chaithirayanon K and Vivithanaporn P: Cysteinyl leukotriene receptor antagonists induce apoptosis and inhibit proliferation of human glioblastoma cells by downregulating B-cell lymphoma 2 and inducing cell cycle arrest. Can J Physiol Pharmacol. 96:798–806. 2018. View Article : Google Scholar : PubMed/NCBI | |
|
Phuagkhaopong S, Ospondpant D, Kasemsuk T, Sibmooh N, Soodvilai S, Power C and Vivithanaporn P: Cadmium-induced IL-6 and IL-8 expression and release from astrocytes are mediated by MAPK and NF-κB pathways. Neurotoxicology. 60:82–91. 2017. View Article : Google Scholar : PubMed/NCBI | |
|
Schmittgen TD and Livak KJ: Analyzing real-time PCR data by the comparative C(T) method. Nat Protoc. 3:1101–1108. 2008. View Article : Google Scholar : PubMed/NCBI | |
|
Aguilar-Quesada R, Munoz-Gamez JA, Martin-Oliva D, Peralta A, Valenzuela MT, Matínez-Romero R, Quiles-Pérez R, Menissier-de Murcia J, de Murcia G, Ruiz de Almodóvar M and Oliver FJ: Interaction between ATM and PARP-1 in response to DNA damage and sensitization of ATM deficient cells through PARP inhibition. BMC Mol Biol. 8:292007. View Article : Google Scholar : PubMed/NCBI | |
|
Clarke R, Cook KL, Hu R, Facey CO, Tavassoly I, Schwartz JL, Baumann WT, Tyson JJ, Xuan J, Wang Y, et al: Endoplasmic reticulum stress, the unfolded protein response, autophagy, and the integrated regulation of breast cancer cell fate. Cancer Res. 72:1321–1331. 2012. View Article : Google Scholar : PubMed/NCBI | |
|
Sisinni L, Pietrafesa M, Lepore S, Maddalena F, Condelli V, Esposito F and Landriscina M: Endoplasmic reticulum stress and unfolded protein response in breast cancer: The balance between apoptosis and autophagy and its role in drug resistance. Int J Mol Sci. 20:8572019. View Article : Google Scholar : PubMed/NCBI | |
|
Ye J, Rawson RB, Komuro R, Chen X, Davé UP, Prywes R, Brown MS and Goldstein JL: ER stress induces cleavage of membrane-bound ATF6 by the same proteases that process SREBPs. Mol Cell. 6:1355–1364. 2000. View Article : Google Scholar : PubMed/NCBI | |
|
Vermeulen K, Berneman ZN and Van Bockstaele DR: Cell cycle and apoptosis. Cell Prolif. 36:165–175. 2003. View Article : Google Scholar : PubMed/NCBI | |
|
Finkelman BS, Zhang H, Hicks DG and Turner BM: The Evolution of Ki-67 and Breast Carcinoma: Past observations, present directions, and future considerations. Cancers (Basel). 15:8082023. View Article : Google Scholar : PubMed/NCBI | |
|
Zhu H and Dogan BE: American Joint Committee on Cancer's Staging System for Breast Cancer, Eighth Edition: Summary for Clinicians. Eur J Breast Health. 17:234–238. 2021. View Article : Google Scholar : PubMed/NCBI | |
|
Paruchuri S, Mezhybovska M, Juhas M and Sjolander A: Endogenous production of leukotriene D4 mediates autocrine survival and proliferation via CysLT1 receptor signalling in intestinal epithelial cells. Oncogene. 25:6660–6665. 2006. View Article : Google Scholar : PubMed/NCBI | |
|
Vermeulen K, Van Bockstaele DR and Berneman ZN: The cell cycle: A review of regulation, deregulation and therapeutic targets in cancer. Cell Prolif. 36:131–149. 2003. View Article : Google Scholar : PubMed/NCBI | |
|
Stacey DW: Three observations that have changed our understanding of cyclin D1 and p27 in cell cycle control. Genes Cancer. 1:1189–1199. 2010. View Article : Google Scholar : PubMed/NCBI | |
|
Hui L, Zheng Y, Yan Y, Bargonetti J and Foster DA: Mutant p53 in MDA-MB-231 breast cancer cells is stabilized by elevated phospholipase D activity and contributes to survival signals generated by phospholipase D. Oncogene. 25:7305–7310. 2006. View Article : Google Scholar : PubMed/NCBI | |
|
Georgakilas AG, Martin OA and Bonner WM: p21: A Two-Faced Genome Guardian. Trends Mol Med. 23:310–319. 2017. View Article : Google Scholar : PubMed/NCBI | |
|
Warfel NA and El-Deiry WS: p21WAF1 and tumourigenesis: 20 years after. Curr Opin Oncol. 25:52–58. 2013. View Article : Google Scholar : PubMed/NCBI | |
|
Braal CL, Jongbloed EM, Wilting SM, Mathijssen RHJ, Koolen SLW and Jager A: Inhibiting CDK4/6 in breast cancer with palbociclib, ribociclib, and abemaciclib: similarities and differences. Drugs. 81:317–331. 2021. View Article : Google Scholar : PubMed/NCBI | |
|
Matsuse H and Kohno S: Leukotriene receptor antagonists pranlukast and montelukast for treating asthma. Expert Opin Pharmacother. 15:353–363. 2014. View Article : Google Scholar : PubMed/NCBI | |
|
Law SWY, Wong AYS, Anand S, Wong ICK and Chan EW: Neuropsychiatric events associated with leukotriene-modifying agents: A systematic review. Drug Saf. 41:253–265. 2018. View Article : Google Scholar : PubMed/NCBI | |
|
Marques CF, Marques MM and Justino GC: Leukotrienes vs. Montelukast-Activity, Metabolism, and Toxicity Hints for Repurposing. Pharmaceuticals (Basel). 15:10392022. View Article : Google Scholar : PubMed/NCBI | |
|
Zovko A, Yektaei-Karin E, Salamon D, Nilsson A, Wallvik J and Stenke L: Montelukast, a cysteinyl leukotriene receptor antagonist, inhibits the growth of chronic myeloid leukemia cells through apoptosis. Oncol Rep. 40:902–908. 2018.PubMed/NCBI | |
|
Burke L, Butler CT, Murphy A, Moran B, Gallagher WM, O'Sullivan J and Kennedy BN: Evaluation of cysteinyl leukotriene signaling as a therapeutic target for colorectal cancer. Front Cell Dev Biol. 4:1032016. View Article : Google Scholar : PubMed/NCBI | |
|
Sharpe JC, Arnoult D and Youle RJ: Control of mitochondrial permeability by Bcl-2 family members. Biochim Biophys Acta. 1644:107–113. 2004. View Article : Google Scholar : PubMed/NCBI | |
|
Savari S, Liu M, Zhang Y, Sime W and Sjolander A: CysLT(1)R antagonists inhibit tumor growth in a xenograft model of colon cancer. PLoS One. 8:e734662013. View Article : Google Scholar : PubMed/NCBI | |
|
Konopleva M, Zhao S, Xie Z, Segall H, Younes A, Claxton DF, Estrov Z, Kornblau SM and Andreeff M: Apoptosis. Molecules and mechanisms. Adv Exp Med Biol. 457:217–236. 1999. View Article : Google Scholar : PubMed/NCBI | |
|
Li X, He S and Ma B: Autophagy and autophagy-related proteins in cancer. Mol Cancer. 19:122020. View Article : Google Scholar : PubMed/NCBI | |
|
Elrashidy RA and Hasan RA: Modulation of autophagy and transient receptor potential vanilloid 4 channels by montelukast in a rat model of hemorrhagic cystitis. Life Sci. 278:1195072021. View Article : Google Scholar : PubMed/NCBI | |
|
Koller A, Bruckner D, Aigner L, Reitsamer H and Trost A: Cysteinyl leukotriene receptor 1 modulates autophagic activity in retinal pigment epithelial cells. Sci Rep. 10:176592020. View Article : Google Scholar : PubMed/NCBI | |
|
Hu H, Tian M, Ding C and Yu S: The C/EBP Homologous Protein (CHOP) transcription factor functions in endoplasmic reticulum stress-induced apoptosis and microbial infection. Front Immunol. 9:30832018. View Article : Google Scholar : PubMed/NCBI | |
|
Rozpedek W, Pytel D, Mucha B, Leszczynska H, Diehl JA and Majsterek I: The Role of the PERK/eIF2α/ATF4/CHOP signaling pathway in tumor progression during endoplasmic reticulum stress. Curr Mol Med. 16:533–544. 2016. View Article : Google Scholar : PubMed/NCBI | |
|
Brush MH, Weiser DC and Shenolikar S: Growth arrest and DNA damage-inducible protein GADD34 targets protein phosphatase 1 alpha to the endoplasmic reticulum and promotes dephosphorylation of the alpha subunit of eukaryotic translation initiation factor 2. Mol Cell Biol. 23:1292–1303. 2003. View Article : Google Scholar : PubMed/NCBI | |
|
Iurlaro R and Munoz-Pinedo C: Cell death induced by endoplasmic reticulum stress. FEBS J. 283:2640–2652. 2016. View Article : Google Scholar : PubMed/NCBI | |
|
Hsu HY, Lin TY, Hu CH, Shu DTF and Lu MK: Fucoidan upregulates TLR4/CHOP-mediated caspase-3 and PARP activation to enhance cisplatin-induced cytotoxicity in human lung cancer cells. Cancer Lett. 432:112–120. 2018. View Article : Google Scholar : PubMed/NCBI | |
|
Zheng YZ, Cao ZG, Hu X and Shao ZM: The endoplasmic reticulum stress markers GRP78 and CHOP predict disease-free survival and responsiveness to chemotherapy in breast cancer. Breast Cancer Res Treat. 145:349–358. 2014. View Article : Google Scholar : PubMed/NCBI | |
|
Wolf C, Smith S and van Wijk SJL: Zafirlukast Induces VHL- and HIF-2alpha-dependent oxidative cell death in 786-O clear cell renal carcinoma cells. Int J Mol Sci. 23:35672022. View Article : Google Scholar : PubMed/NCBI | |
|
Abdel-Raheem IT and Khedr NF: Renoprotective effects of montelukast, a cysteinyl leukotriene receptor antagonist, against methotrexate-induced kidney damage in rats. Naunyn Schmiedebergs Arch Pharmacol. 387:341–353. 2014. View Article : Google Scholar : PubMed/NCBI | |
|
Pu S, Liu Q, Li Y, Li R, Wu T, Zhang Z, Huang C, Yang X and He J: Montelukast prevents mice against acetaminophen-induced liver injury. Front Pharmacol. 10:10702019. View Article : Google Scholar : PubMed/NCBI | |
|
Fei Z, Zhang L, Wang L, Jiang H and Peng A: Montelukast ameliorated pemetrexed-induced cytotoxicity in hepatocytes by mitigating endoplasmic reticulum (ER) stress and nucleotide oligomerization domain-like receptor protein 3 (NLRP3) activation. Bioengineered. 13:7894–7903. 2022. View Article : Google Scholar : PubMed/NCBI | |
|
Fleifel AM, Soubh AA, Abdallah DM, Ahmed KA and El-Abhar HS: Preferential effect of Montelukast on Dapagliflozin: Modulation of IRS-1/AKT/GLUT4 and ER stress response elements improves insulin sensitivity in soleus muscle of a type-2 diabetic rat model. Life Sci. 307:1208652022. View Article : Google Scholar : PubMed/NCBI | |
|
Cheng H, Leff JA, Amin R, Gertz BJ, De Smet M, Noonan N, Rogers JD, Malbecq W, Meisner D and Somers G: Pharmacokinetics, bioavailability, and safety of montelukast sodium (MK-0476) in healthy males and females. Pharm Res. 13:445–448. 1996. View Article : Google Scholar : PubMed/NCBI | |
|
Dekhuijzen PN and Koopmans PP: Pharmacokinetic profile of zafirlukast. Clin Pharmacokinet. 41:105–114. 2002. View Article : Google Scholar : PubMed/NCBI | |
|
Woodring RN, Gurysh EG, Bachelder EM and Ainslie KM: Drug delivery systems for localized cancer combination therapy. ACS Appl Bio Mater. 6:934–950. 2023. View Article : Google Scholar : PubMed/NCBI | |
|
Pandey M, Wen PX, Ning GM, Xing GJ, Wei LM, Kumar D, Mayuren J, Candasamy M, Gorain B, Jain N, et al: Intraductal delivery of nanocarriers for ductal carcinoma in situ treatment: A strategy to enhance localized delivery. Nanomedicine (Lond). 17:1871–1889. 2022. View Article : Google Scholar : PubMed/NCBI | |
|
Du C, Zhang Q, Wang L, Wang M, Li J and Zhao Q: Effect of montelukast sodium and graphene oxide nanomaterials on mouse asthma model. J Nanosci Nanotechnol. 21:1161–1168. 2021. View Article : Google Scholar : PubMed/NCBI | |
|
Accolate (zafirlukast). AstraZeneca Pharmaceuticals LP; Wilmington, DE: 2009 | |
|
Huang CK and Handel N: Effects of Singulair (montelukast) treatment for capsular contracture. Aesthet Surg J. 30:404–408. 2010. View Article : Google Scholar : PubMed/NCBI | |
|
Scuderi N, Mazzocchi M, Fioramonti P and Bistoni G: The effects of zafirlukast on capsular contracture: Preliminary report. Aesthetic Plast Surg. 30:513–520. 2006. View Article : Google Scholar : PubMed/NCBI | |
|
Saier L, Ribeiro J, Daunizeau T, Houssin A, Ichim G, Barette C, Bouazza L and Peyruchaud O: Blockade of Platelet CysLT1R receptor with zafirlukast counteracts platelet protumoral action and prevents breast cancer metastasis to bone and lung. Int J Mol Sci. 23:122212022. View Article : Google Scholar : PubMed/NCBI | |
|
El-Ashmawy NE, Khedr EG, Khedr NF and El-Adawy SA: Suppression of epithelial-mesenchymal transition and SIRT1/AKT signaling pathway in breast cancer by montelukast. Int Immunopharmacol. 119:1101482023. View Article : Google Scholar : PubMed/NCBI |