Knockdown of miR-15b partially reverses the cisplatin resistance of NSCLC through the GSK-3β/MCL-1 pathway

Induction of acquired drug resistance occurs frequently with cisplatin-based therapy for non-small cell lung cancer (NSCLC). As recent studies have demonstrated that deregulation of microRNAs (miRNAs) is associated with drug resistance in cancers, correcting the deregulation of miRNAs represents a promising strategy to reverse acquired resistance in NSCLC. This study investigated the functional role of miR-15b in cisplatin resistance in NSCLC. Cisplatin-resistant PC9 and A549 NSCLC cell lines (PC9-R and A549-R) were established through long-term exposure to cisplatin. Differences in miR-15b expression between cisplatin-resistant NSCLC cell lines and their parental cell lines were identified through quantitative real-time polymerase chain reaction (qRT-PCR). The effect of anti-miR-15b on the sensitivity of PC9-R and A549-R to cisplatin-induced cytotoxicity was evaluated using Cell Counting Kit-8 (CCK-8) assays. Regulation of GSK-3β by miR-15b was confirmed with luciferase reporter assays. Cell apoptosis and mitochondrial membrane potential (MMP) were measured using flow cytometry analysis. In PC9-R and A549-R cells, miR-15b was significantly overexpressed. However, knockdown of miR-15b clearly reduced cisplatin resistance in PC9-R and A549-R cells. Researching the mechanism, we proved that GSK-3β was the target of miR-15b. Knockdown of miR-15b significantly increased the expression GSK-3β and thus promoted the degradation of MCL-1, which is a key anti-apoptosis protein. As a result, anti-miR-15b expanded the cisplatin-induced apoptosis in cisplatin-resistant NSCLC cells. Knockdown of miR-15b partially reversed cisplatin resistance in NSCLC cells through the GSK-3β/MCL-1 pathway.