ABSTRACT
Montelukast and zafirlukast, cysteinyl leukotriene receptor antagonists (LTRAs), trigger apoptosis and inhibit cell proliferation of triplenegative breast cancer MDAMB231 cells. By contrast, only zafirlukast induces G0/G1 cell cycle arrest. The present study compared the effects of these drugs on proteins regulating cell proliferation, apoptosis, autophagy, and endoplasmic reticulum (ER) and oxidative stress using reverse transcriptionquantitative PCR, western blotting and flow cytometry. The expression of proliferating markers, Ki67 and proliferating cell nuclear antigen, was decreased by both drugs. Zafirlukast, but not montelukast, decreased the expression of cyclin D1 and CDK4, disrupting progression from G1 to S phase. Zafirlukast also increased the expression of p27, a cell cycle inhibitor. Both drugs decreased the expression of antiapoptotic protein Bcl2 and ERK1/2 phosphorylation, and increased levels of the autophagy marker LC3II and DNA damage markers, including cleaved PARP1, phosphorylated (p)ATM and phistone H2AX. The number of caspase 3/7positive cells was greater in montelukasttreated cells compared with zafirlukasttreated cells. Montelukast induced higher levels of the ER stress marker CHOP compared with zafirlukast. Montelukast activated PERK, activating transcription factor 6 (ATF6) and inositolrequiring enzyme type 1 (IRE1) pathways, while zafirlukast only stimulated ATF6 and IRE1 pathways. GSK2606414, a PERK inhibitor, decreased apoptosis mediated by montelukast, but did not affect zafirlukastinduced cell death. The knockdown of CHOP by small interfering RNA reduced apoptosis triggered by montelukast and zafirlukast. In conclusion, the effects on cell cycle regulator proteins may contribute to cell cycle arrest caused by zafirlukast. The greater apoptotic effects of montelukast may be caused by the higher levels of activated caspase enzymes and the activation of three pathways of ER stress: PERK, ATF6, and IRE1.
Subject(s)
Acetates , Apoptosis , Autophagy , Cyclopropanes , DNA Damage , Endoplasmic Reticulum Stress , Indoles , Quinolines , Sulfides , Sulfonamides , Humans , Sulfides/pharmacology , Cyclopropanes/pharmacology , Quinolines/pharmacology , Apoptosis/drug effects , Acetates/pharmacology , Endoplasmic Reticulum Stress/drug effects , Cell Line, Tumor , Autophagy/drug effects , Sulfonamides/pharmacology , Indoles/pharmacology , Female , DNA Damage/drug effects , Phenylcarbamates/pharmacology , Tosyl Compounds/pharmacology , Cell Proliferation/drug effects , eIF-2 Kinase/metabolism , eIF-2 Kinase/genetics , Endoribonucleases/metabolism , Endoribonucleases/genetics , Cell Cycle Checkpoints/drug effects , Transcription Factor CHOP/metabolism , Transcription Factor CHOP/genetics , Cell Cycle/drug effects , Leukotriene Antagonists/pharmacology , Protein Serine-Threonine Kinases/metabolism , Protein Serine-Threonine Kinases/geneticsABSTRACT
Despite a discovery of hormonal pathways regulating breast cancer, a definitive cure for the disease requires further identification of alternative targets that provide a hormone-independent support. Apart from their role in inflammatory diseases, cysteinyl leukotriene (CysLT) receptor antagonists (LTRAs) decrease the risk of lung cancer in asthma patients and inhibit tumor progression in several malignancies. In the present study, we evaluate the effects of two chemically different, clinically relevant LTRAs (montelukast and zafirlukast) in a triple negative breast cancer cell line, MDAMB- 231. We found that these two LTRAs reduced breast cancer cell viability in a dose-dependent manner with the 50% inhibitory concentration (IC50) between 5-10 µM. Although both LTRAs have several pharmacological properties in common, we noticed that montelukast mainly induced apoptosis, while zafirlukast mainly exerted its action on cell cycle. However, the precise mechanisms responsible for such different effects remain unclear. In summary, our results suggest that CysLT plays a role in proliferation and survivability of breast cancer cells in the absence of hormonal stimuli.
