Cisplatin-based chemotherapy is the most commonly used treatment regimen for lung cancer. Cancer stem cells (CSCs) are postulated to be important promoters of drug resistance. We previously found that miR-5100 is overexpressed in lung cancer, but it is unknown whether and how miR-5100 regulates cisplatin resistance. Here, we demonstrated that miR-5100 was significantly up-regulated in CD44+ CD133+ lung cancer stem cells (LCSCs) compared with non-CSCs. Additionally, over-expression of miR-5100 increased CSC properties, cell growth, and tumor sphere formation in lung cancer cell line A549 or H1299, and that miR-5100 inhibitor significantly increased sensitivity of LCSCs to cisplatin in vitro. Surprisingly, the combination with miR-5100 inhibitor significantly decreased the IC50 of LCSCs to cisplatin. Furthermore, miR-5100 increased CSC properties and cisplatin resistance by inhibiting Rab6, a direct target gene of miR-5100. We demonstrated that miR-5100 overexpression increases the cisplatin resistance of the LCSCs through the mitochondrial apoptosis pathway. In conclusion, our results suggest that miR-5100 increases the cisplatin resistance of the LCSCs by inhibiting the Rab6. This study provides novel insight into the regulation of LCSCs by miRNA.
KEYWORDS: MiR-5100, cancer stem cells, chemoresistance, cisplatin