Effect of dual mTOR inhibitor on TGFβ1-induced fibrosis in primary human urethral scar fibroblasts.

BACKGROUND

TGFβ1 and mTOR are considered to play important roles in fibrotic diseases. Rapamycin has been reported to inhibit urethral stricture formation in a rabbit model of urethral fibrosis.

AIM: To evaluate if dual mTOR inhibitor has a superior efficacy compared with rapamycin on inhibiting cell proliferation and collagen expression in human urethral scar fibroblasts (HUSFs).

METHODS

We established HUSF cultures from fresh surgical specimen. The HUSFs were identified with typical fibroblast markers using immunofluorescence. Then we examined the effect of TGFβ1 on HUSFs using Cell Counting Kit-8 and Western blot. The inhibiting effects of OSI-027 (a dual mTOR inhibitor) on cell proliferation and collagen expression in TGFβ1-induced HUSFs were compared with rapamycin using Cell Counting Kit-8, Western blot, and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).

RESULTS

HUSFs were stained positive for vimentin, collagen I, and collagen III. TGFβ1 had no effect on cell proliferation but increased collagen I and collagen III expressions in HUSFs. OSI-027 was more effective inhibiting cell proliferation and collagen expression compared with rapamycin in TGFβ1-induced HUSFs. OSI-027 played a more important role in inhibiting TGFβ1-induced mTOR pathway and phosphorylation of Smad2 compared with rapamycin in HUSFs.

CONCLUSION

OSI-027 can inhibit the pro-fibrotic effects of TGFβ1 significantly compared with rapamycin in HUSFs. These findings may provide a new therapy in the adjunctive treatment of urethral stricture disease.