Abstract
Breast cancer (BC) is the leading cause of death in females worldwide. Although cisplatin is a strong-effect and broad-spectrum chemotherapy drug, resistance to cisplatin remains a significant factor effecting clinical efficacy. The underlying mechanism of cancer cell resistance to cisplatin is not fully understood. MicroRNAs (miRs/miRNAs), as a regulator, are involved in regulating chemosensitivity to numerous chemotherapeutic drugs. The present study aimed to investigate the function of miR-181a-5p as a potential tumor suppressor in improving the efficiency of cisplatin in BC. The IC50 of cisplatin and miR-181a-5p expression were determined in five BC cell lines, and HS578T was selected as an appropriate cell line for subsequent experiments. The sensitivity of HS578T cells to cisplatin was assessed using cell proliferation, migration and apoptosis assays. Western blotting was performed to detect the expression of vitamin D receptor (VDR) and autophagy in HS578T cells. It was found that the increase in autophagy resulted in increased apoptosis and sensitivity to cisplatin in HS578T cells. miR-181a-5p transfection also inhibited the proliferation and migration ability of HS578T cells and induced apoptosis. Meanwhile, HS578T cells have increased sensitivity to cisplatin. VDR, as a target gene and autophagy regulator of miR-181a-5p, was negatively regulated by miR-181a-5p. Upon the decrease in VDR expression, the autophagy in HS578T cells was increased. These results indicate that the increase in autophagy enhanced the chemosensitivity of cisplatin by inducing apoptosis of HS578T cells and by inhibiting proliferation and migration. The present study showed that miR-181a-5p increased the chemical sensitivity of HS578T cells to cisplatin by inhibiting VDR to promote autophagy. The use of miR-181a-5p/autophagy/VDR-based treatment strategies may be a potential method to overcome cisplatin resistance in BC.