Knockdown of KLF5 suppresses hypoxia-induced resistance to cisplatin in NSCLC cells by regulating HIF-1α-dependent glycolysis through inactivation of the PI3K/Akt/mTOR pathway

Abstract

BackgroundHypoxia-mediated chemoresistance has been regarded as an important obstacle in the development of cancer treatment. Knockdown of krüppel-like factor 5 (KLF5) was reported to inhibit hypoxia-induced cell survival and promote cell apoptosis in non-small cell lung cancer (NSCLC) cells via direct regulation of hypoxia inducible factor-1α (HIF-1α) expression. However, the roles of KLF5 in the development of hypoxia-induced cisplatin (DDP) resistance and its underlying mechanism in NSCLC cells remain to be further elucidated.MethodsWestern blot was performed to determine the protein levels of KLF5, P-glycoprotein (P-gp) and HIF-1α in treated NSCLC cells. Cell survival was examined by MTT assay. The effect of KLF5 knockdown on hypoxia-induced glycolysis was assessed by measuring glucose consumption and lactate production. The effect of KLF5 knockdown on the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway was analyzed by western blot.ResultsHypoxia upregulated the expression of KLF5 in NSCLC cells. KLF5 knockdown suppressed hypoxia-induced DDP resistance in NSCLC cells, as demonstrated by the increased cytotoxic effects of DDP and reduced P-gp expression in NSCLC cells in hypoxia. Moreover, KLF5 knockdown inhibited hypoxia-induced HIF-1α expression and glycolysis, and KLF5 knockdown suppressed hypoxia-induced DDP resistance by inhibiting HIF-1α-dependent glycolysis in NSCLC cells. Furthermore, KLF5 knockdown suppressed hypoxia-induced activation of the PI3K/Akt/mTOR pathway in NSCLC cells and KLF5 overexpression promoted hypoxia-induced DDP resistance in NSCLC cells through activation of the PI3K/Akt/mTOR pathway.ConclusionsKLF5 knockdown could suppress hypoxia-induced DDP resistance, and its mechanism may be due to the inhibition of HIF-1α-dependent glycolysis via inactivation of the PI3K/Akt/mTOR pathway.

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

“…demonstrated that IGF‐1 decreases radiation‐induced phosphorylation of Chk1 at S345 or S296 via the PI3K/AKT pathway . Notably, various studies have confirmed that KLF5 plays critical roles in the PI3K/Akt/mTOR pathway . Moreover, phosphorylation of Chk2 at T68 in response to DNA damage occurs in ATM‐deficient cells, suggesting that kinases other than ATM may be involved .…”

“…20 In ovarian cancer cell lines, silencing KLF5 by small interfering RNA sensitizes cells to apoptosis induced by cisplatin. 21 A previous study reported that KLF5 knockdown could suppress hypoxia-induced cisplatin resistance in NSCLC, probably via inactivation of the PI3K/Akt/ mTOR pathway; 13 however, the study failed to mention the prognostic value of KLF5 and its underlying roles in the DDR in NSCLC.…”

“…27 Notably, various studies have confirmed that KLF5 plays critical roles in the PI3K/Akt/mTOR pathway. 11,13 Moreover, phosphorylation of Chk2 at T68 in response to DNA damage occurs in ATM-deficient cells, suggesting that kinases other than ATM may be involved. 28 Thus, this study provides proof for further investigation of the role of KLF5 in regulating the phosphorylation of Chk1 and Chk2.…”

“…In cancer, KLF5 is typically pro‐proliferative by regulating cell cycle progression . Recently, studies have demonstrated that knockdown of KLF5 suppresses hypoxia‐induced cisplatin resistance in NSCLC cells . In the intestine, KLF5 may affect DNA damage repair pathways .…”

“…11,12 Recently, studies have demonstrated that knockdown of KLF5 suppresses hypoxia-induced cisplatin resistance in NSCLC cells. 13 In the intestine, KLF5 may affect DNA damage repair pathways. 14 Given this background, we hypothesized that KLF5 may regulate cisplatin resistance through the DDR in NSCLC.…”