CHK1 Inhibition Overcomes Gemcitabine Resistance in Non-Small Cell Lung Cancer Cell A549

Abstract

Abstract Lung cancer is a very common cancer diagnosed and the leading cause of cancer death. Among them, the treatment options for non-small cell lung cancer cell (NSCLC) are very limited, mainly due to the frequent development of anti-cancer drug resistance. Targeted DNA repair mechanisms have reached clinical application, and new therapeutic strategies including targeting cell cycle checkpoint sites, such as ATR and CHK1, are currently under clinical development. In this study, NSCLC A549 cells and gemcitabine-resistant strain A549/G+ cells were used to explore the synergistic effect of CHK1 inhibition and gemcitabine, and to evaluate the potential of overcoming drug resistance and related molecular mechanisms. Our results showed that inhibition of CHK1 and gemcitabine combination significantly reduced the proliferation ability of the two cell lines. We also revealed the effect of full-length PARP degradation and reduced Bcl-2/Bax ratio on increased apoptosis. Inhibition of CHK1 expression leads to DNA damage, induces phosphorylation of γ-H2AX, and affects the repair of homologous recombination ability through Rad51. Mechanistically, gemcitabine increased phosphorylation-ATR (pATR) and phosphorylation-CHK1 (pCHK1), indicating activation of the DNA repair system and ATR-CHK1-CDC25A pathway. Inhibition of CHK1 resulted in increased synthesis of CDK2/Cyclin A2 and CDK2/Cyclin E1 complexes, and more cells entered the subsequent cell cycle, leading to S phase arrest and mitotic catastrophe. In conclusion, in our study, we identified inhibition of CHK1 as a potential treatment for NSCLC and confirmed that inhibition of this kinase can overcome acquired gemcitabine resistance.