miR-17-5p promotes proliferation and migration of CAL-27 human tongue squamous cell carcinoma cells involved in autophagy inhibition under hypoxia.

Autophagy contributes to head and neck squamous cell carcinoma (HNSCC) development and progression. MiR-17-5p down-regulates Beclin-1 and thus plays an important role in autophagy, but little is known about the function and regulation of miR-17-5p in HNSCC autophagy. This study aimed to investigate the role of miR-17-5p on proliferation, migration, and autophagy under hypoxia in CAL-27 human tongue squamous cell carcinoma cells. CAL-27 cells were transfected with 50 nmol miR-17-5p mimics to overexpress miR-17-5p. Cell proliferation and migration were determined by CCK-8 and wound healing assays, respectively, under hypoxia. Autophagy induced by hypoxia was detected by transmission electron microscope and Beclin-1 mRNA and protein expressions. The miR-17-5p mimics successfully increased the expression of miR-17-5p in CAL-27 cells by almost 700 fold compared with the miRNA mimic negative control. After 3 days, cells transfected with the miR-17-5p mimics showed higher proliferation compared with controls ( < 0.05) under hypoxia. MiR-17-5p transfected CAL-27 cells had a higher migratory capacity compared with the control cells ( < 0.05) under hypoxia. Furthermore, transmission electron microscopy showed that miR-17-5p overexpression inhibited the formation of autophagosomes in hypoxic cells. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot showed that miR-17-5p overexpression inhibited the mRNA and protein expression of Beclin-1 in CAL-27 cells submitted to hypoxia. MiR-17-5p overexpression promoted the proliferation and migration of the CAL-27 cells, but inhibited autophagy under hypoxia.