A preliminary study of the role of miR-193a-3p in radioresistance of esophageal cancer cells

Objective: To investigate the role of miR-193a-3p in the radioresistance of esophageal squamous cell carcinoma (ESCC). Methods: MTT assay was used to identify the cell lines with the highest radiosensitivity and radioresistance in four esophageal cancer cell lines exposed to irradiation of 6 MV X-ray. Stem-loop quantitative real-time PCR was used to measure the expression levels of miR-193a-3p, miR-155, and miR-22-3P in the two cell lines. Further studies were performed on miR-193a-3p because of the substantial difference in its expression between the two cell lines. The mimic (3PM) and antagomiR (3PA) of miR-193a-3p as well as siRNA (si-L0XL4) were synthesized and transfected into cells to elevate and inhibit miR-193a-3p expression. MTT assay and flow cytometry were used to evaluate the effects of miR-193a-3p and its downstream gene L0XL4 on radiosensitivity. Results: KYSE510 and KYSE410 were characterized as cell lines with the highest radiosensitivity and radioresistance, respectively. miR-193a-3p had a substantially larger difference in expression between the two cell lines than miR-155 or miR-22-3P (1.00 : 21.00). Transfection of 3PM resulted in elevated expression of miR-193a-3p in KYSE510, which had a significantly lower radiosensitivity and a significantly reduced apoptosis ratio by 11.01% compared with the control group (P < 0.05). KYSE410 transfected with 3PA had a significantly higher radiosensitivity (P < 0.05). The expression of L0XL4, a downstream gene of miR-193a-3p, was negatively correlated with miR-193a-3p expression. Transfection with si-L0XL4 inhibited the expression of L0XL4, which resulted in a significantly lower radiosensitivity and a significantly reduced apoptosis ratio by 7.07% compared with the control group (P < 0.05). Conclusions: miR-193a-3p promotes the radioresistance of esophageal cancer cells probably by regulation of L0XL4. (authors)