Downregulation of miR-761 ameliorates radiation-induced pulmonary fibrosis by regulating PGC-1α.

Background: Radiation-induced pulmonary fibrosis (RIPF) is a serious complication in patients treated with transthoracic irradiation. To date, there are no effective drugs for RIPF treatment. In this study, we attempted to explore the function of miR-761 in RIPF, further investigate its potential mechanism and evaluate its effectiveness in the treatment of RIPF. Methods: qRT-PCR analysis was used to detect miR-761 and peroxisome proliferator-activated receptor gamma (PPARg) coactivator-1 (PGC-1α) expression. Western Blot (WB) assay was applied to verify the regulation of PGC-1α by miR-761 and the expression of fibrosis-related proteins. Gel contraction assay was performed to demonstrate the level of fibroblast activation in vitro. A mouse RIPF model was used to validate the anti-fibrotic effect of Antagomir761. Bioinformatics analysis and dual-luciferase reporter assays were utilized to confirm the regulation relationship between miR-761 and PGC-1α. Results: The results showed that miR-761 was significantly elevated in irradiated mice lungs and fibroblasts. Overexpression of miR-761 in vitro promoted fibroblast activation. Whereas inhibition of miR-761 attenuated the degree of RIPF and inhibited fibroblast activation. Mechanistically, PGC-1α was a direct and functional target of miR-761, overexpression of PGC-1α inhibited irradiation-induced fibroblast activation, and knockdown of PGC-1α caused miR-761 inhibitor loses its anti-activation ability in irradiated cells. Conclusion: Our findings demonstrated that miR-761 regulated RIPF by targeting PGC-1α. Inhibition of miR-761 restored PGC-1α expression and attenuated RIPF damage, and miR-761 was a potential target for preventing the development of RIPF.