Abstract: Objective To explore the role and potential mechanism of miR-27b-3p in the proliferation, apoptosis and cisplatin (DDP) resistance of oral squamous cell carcinoma (OSCC) resistant cells. Methods RT-qPCR was applied to detect the expression of miR-27b-3p and HOXB8 mRNA. Western blotting was applied to detect the expression of HOXB8 and drug resistance protein MRP1. CCK-8 assay was conducted to measure the cell viability, colony formation assay was used to analyze cell proliferation, and flow cytometry to detect apoptosis. The interaction between miR-27b-3p and HOXB8 was predicted by the online software Targetscan and confirmed by dual-luciferase reporter gene assay. A nude mouse xenograft model was used to test the role of miR-27b-3p in OSCC DDP resistance in vivo. Results The expression level of miR-27b-3p was obviously lower in DDP resistant OSCC tissues and OSCC cell lines, and the expression level in DDP-resistant OSCC cell lines (CAL-27 / DDP) was obviously lower than that in normal OSCC cell lines (CAL-27) (P < 0. 05). HOXB8 mRNA, by contrast, was highly expressed in DDP-resistant OSCC tissues and OSCC cell lines, and the expression in DDP-resistant OSCC cell line (CAL-27 / DDP) was obviously higher than that in normal OSCC cell line (CAL-27) (P < 0. 05). miR-27b-3p mimic could obviously inhibit the cell viability, colony formation ability and the expression of drug resistance protein MRP1 in CAL-27 / DDP cells, and promote the cell apoptosis (P < 0. 05) . Overexpression of HOXB8 could partially reverse the effects of miR-27b-3p mimics on the proliferation, apoptosis and drug resistance in CAL-27 / DDP cells (P< 0. 05). HOXB8 had a targeted regulatory role with miR-27b-3p. Intratumoral injection of miR-27b-3p agomir obviously alleviated the growth of resistant cells in the xenograft in vivo, and reduce the expression level of HOXB8 and MRP1 (P< 0. 05). Conclusion miR-27b-3p may regulate the proliferation, apoptosis and DDP resistance of OSCC drug resistant cells by targeting HOXB8.

Key words: miR-27b-3p, HOXB8, oral squamous cell carcinoma, proliferation, apoptosis; drug resistance