RESUMO
Objective:To evaluate the effect of circLPAR3 on the radiosensitivity of esophageal cancer cells and investigate its mechanism.Methods:The cancer tissues and and adjacent tissues of 37 patients with esophageal cancer were collected, and esophageal cancer cell lines Eca-109, EC9706 and KYSE30 and esophageal epithelial cells HET-1A were cultured in vitro. The expression levels of circLPAR3 and miR-1238 in the tissues and cells were measured by RT-qPCR. Eca-109 cells were transfected with circLPAR3 siRNA and miR-1238 mimics or co-transfected with circLPAR3 siRNA and miR-1238 inhibitor. Cell cloning experiment was conducted to evaluate the effects of silencing circLPAR3, overexpressing miR-1238, or silencing both circLPAR3 and miR-1238 on the radiosensitivity of Eca-109 cells. After Eca-109 cells that silenced circLPAR3, overexpressed miR-1238 or silenced both circLPAR3 and miR-1238 were exposed to 4 Gy irradiation, CCK-8 assay (A value), flow cytometry and Western blot were employed to assess the effects of silencing circLPAR3, overexpressing miR-1238, or silencing both circLPAR3 and miR-1238 combined with 4 Gy irradiation on the proliferation and apoptosis of Eca-109 cells and the expression levels of CyclinD1, p21, Bcl-2 and Bax proteins. Dual luciferase reporter gene experiment and RNA pull down experiment were performed to verify the regulatory relationship between circLPAR3 and miR-1238. Results:Compared with adjacent tissues, the expression level of circLPAR3 was up-regulated in the esophageal cancer tissues ( P<0.05), while that of miR-1238 was down-regulated ( P<0.05). Compared with HET-1A cells, the expression levels of circLPAR3 were up-regulated in the esophageal cancer cell lines Eca-109, EC9706 and KYSE30(all P<0.05), whereas those of miR-1238 were down-regulated (all P<0.05). Silencing circLPAR3 or overexpressing miR-1238 reduced the survival fraction of Eca-109 cells (all P<0.05), and the sensitization ratio was 1.21 and 1.75, respectively. Silencing circLPAR3 or overexpressing miR-1238 decreased the A value of Eca-109 cells and the expression levels of CyclinD1 and Bcl-2 proteins (all P<0.05), while increased the apoptosis rate of Eca-109 cells and the expression levels of p21 and Bax proteins (all P<0.05). After silencing circLPAR3 or overexpressing miR-1238 combined with 4 Gy irradiation, the A value of Eca-109 cells and the expression levels of CyclinD1 and Bcl-2 proteins were decreased (all P<0.05), while Eca-109 cell apoptosis rate and the expression levels of p21 and Bax proteins were increased (all P<0.05). circLPAR3 targeted and negatively regulated the expression level of miR-1238 in Eca-109 cells. After silencing miR-1238 and circLPAR3 simultaneously, the survival fraction of Eca-109 cells was higher than that when only silencing circLPAR3, and the sensitization ratio was 0.59. Silencing miR-1238 reversed the effects of silencing circLPAR3 combined with 4 Gy irradiation on the proliferation and apoptosis of Eca-109 cells. Conclusion:circLPAR3 is highly expressed in esophageal cancer tissues and cell lines, and silencing the expression of circLPAR3 can inhibit the proliferation of esophageal cancer Eca-109 cells, promote their apoptosis, and enhance cell radiosensitivity by up-regulating miR-1238.
