Abstract: Objective To observe regulatory mechanism of miR-124-3p. 2 in apoptosis and ferroptosis of oral squamous cell carcinoma cells, and to explore the potential mechanism. 
Methods Real-time fluorescence quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to detect the expression of miR-124-3p.2 and CKLF like MARVEL transmembrane domain gene 6 (CMTM6) in human normal oral epithelial cells NHOK, and oral squamous cell carcinoma cell lines Cal27, SCC-25, HSC-3, and Tca81132, and Cal27 were used to screen the optimal cells. NC group (without any treatment), miR-con group (transfected miR-con), miR-124-3p.2 group (transfected miR-124-3p.2 mimics), si-con group (transfected si-con), si-CMTM6 group (transfected si-CMTM6), miR-124-3p.2+pcDNA group (co-transfected miR-124-3p.2 mimics and pcDNA), and miR-124-3p.2+pcDNA-CMTM6 group (co-transfected miR-124-3p.2 mimics and pcDNA-CMTM6) were transfected into Cal27 by liposome method. Cell proliferation was detected by cell counting kit (CCK8). The protein expressions of CMTM6, recombinant solute carrier family 7, member 11 (SLC7A11), glutathione peroxidase (GPX4) and ferritin, heavy polypeptide 1(FTH1) were detected by Western blot (WB). The content of reactive oxygen species (ROS) was detected by immunofluorescence, and apoptosis was detected by flow cytometry. Double luciferase assay was used to detect the fluorescence activity of cells. 
Results Compared with NHOK, the expression of miR-124-3p.2 in Cal27, SCC-25 and HSC-3 cells was decreased, while the expression of CMTM6 was increased (P＜0.05). The difference of interaction between groups, time points and time points between groups was statistically significant with respect to cell activity in miR-con group and miR-124-3p.2 group (P＜0.05). Compared with the miR-con group, the ROS of cells in the miR-124-3p.2 group, the protein expression of SLC7A11, GPX4 and FTH1, and the apoptosis rate were significantly increased (P＜0.05). The fluorescence activity of CMTM6-WT cells in the miR-124-3p.2 group was significantly decreased, while the fluorescence activity of CMTM6-WT cells in the anti-miR-124-3p.2 group was significantly increased (P＜0.05). The difference of interaction between groups, time points and time points between groups was statistically significant with respect to cell activity in si-con group and si-CMTM6 group (P＜0.05). The difference of interaction between groups, time points and time points between groups was statistically significant with respect to cell activity in miR-124-3p.2+pcDNA group and miR-124-3p.2+pcDNA-CMTM6 group (P＜0.05). 
Conclusion miR-124-3p. 2 promotes apoptosis and ferroptosis of OSCC cells, which may be related to targeting CMTM6.

Key words: neoplasms, squamous cell, apoptosis, ferroptosis