miR-485-3p regulates radiosensitivity of gastric cancer cells by targeting TLR1/NF-kB signaling pathway

Objective: To investigate whether miR-485-3p plays a role in regulation of radiosensitivity of gastric cancer cells by targeting TLR1. Methods: Quantitative real-time PCR and Western blot were used to determine the expression of miR-485-3p and TLR1, respectively. The interaction between miR-485-3p and TLR1 was verified by target prediction software (DIANA, TargetScan, and miRanda) and dual luciferase reporter assay. Gastric cancer MGC803 cells transfected with miR-485-3p mimic or TLR1 siRNA were exposed to irradiation. Apoptosis assay,colony formation assay, and MTT assay were used to evaluate the changes in radiosensitivity of gastric cancer cells. Dual luciferase reporter assay was used to determine the effects of miR-485-3p overexpression and TLR1 silencing on the activity of NF-kB. Western blot was used to study the effects of miR-485-3p overexpression and TLR1 silencing on NF-kB target genes. Results: In gastric cancer cells exposed to radiation, the expression of miR-485-3p was downregulated and the expression of TLR1 was upregulated. TLR1 was predicted to be the target of miR-485-3p by target prediction software. Dual luciferase reporter assay further confirmed TLR1 as the direct target of miR-485-3p. miR-485-3p negatively regulated the expression of TLR1. The overexpression of miR-485-3p, as well as TLR1 silencing, increased the apoptosis rate of cells, reduced colony formation and cell proliferation, and enhanced the radiosensitivity of the cells. Both miR-485-3p overexpression and TLR1 silencing reduced the activity of NF-kB and downregulated the expression of multiple NF-kB target genes. Conclusions: miR-485-3p enhances the radiosensitivity of gastric cancer cells probably by targeting TLR1 and regulating the NF-kB signaling pathway. (authors)