Knockdown of KLF5 promotes cisplatin‐induced cell apoptosis via regulating DNA damage checkpoint proteins in non‐small cell lung cancer

BACKGROUND: Previous research has revealed that Krüppel‐like factor 5 (KLF5) may affect DNA damage repair pathways; however, the associated molecular mechanisms are unclear. METHODS: The expression of KLF5 was studied by immunohistochemical staining in paired tumour and normal tissues from 90 patients with ESCC. We studied the effects of KLF5 knockdown on cell proliferation and apoptosis with or without cisplatin treatment in A549 and H1299 cell lines. Moreover, we examined the effect of KLF5 on the DNA damage response. RESULTS: KLF5 was significantly overexpressed in non‐small cell lung cancer (NSCLC) tissues, and high KLF5 expression predicted poor prognosis for NSCLC patients. The inhibition of KLF5 markedly augmented cisplatin‐induced cell apoptosis. In addition, we observed that KLF5 knockdown could decrease DNA repair potential by inhibiting H2AX S139 phosphorylation in response to cisplatin. Moreover, silencing of KLF5 in NSCLC cell lines inhibited the phosphorylation of checkpoint kinases Chk1 S345 and Chk2 T68. KLF5 knockdown permits cells with broken or damaged DNA strands to enter mitosis by inhibiting the activation of H2AX, Chk1 and Chk2, resulting in mitotic catastrophe. CONCLUSION: KLF5 plays a significant role in the DNA damage response by regulating DNA damage checkpoint proteins. Inhibition of KLF5 may be a potential therapeutic target for NSCLC patients with cisplatin resistance.