RESUMEN
OBJECTIVE: To investigate the effects and the mechanism of action of 2-methoxyestradiol (2ME(2)) on transforming growth factor (TGF) ß3-induced profibrotic response in immortalized human uterine fibroid smooth muscle (huLM) cells. DESIGN: Laboratory study. SETTING: University research laboratory. PATIENTS(S): Not applicable. INTERVENTIONS(S): Not applicable. MAIN OUTCOME MEASURE(S): huLM cells were treated with TGF-ß3 (5 ηg/mL) in the presence or absence of specific Smad3 inhibitor SIS3 (1 µmol/L), inhibitor of the PI3K/Akt (LY294002, 10 µmol/L), or 2ME(2) (0.5 µmol/L), and the expression of collagen (Col) type I(αI), Col III(αI), plasminogen activator inhibitor (PAI) 1, connective tissue growth factor (CTGF), and α-smooth muscle actin (α-SMA) were determined by real-time reverse-transcription polymerase chain reaction and immunoblotting. The effect of 2ME(2) on Smad-microtubule binding was evaluated by coimmunoprecipitation. RESULT(S): Our data revealed that TGF-ß3-induced fibrogenic response in huLM is mediated by both Smad-dependent and Smad-independent PI3K/Akt/mTOR signaling pathways. 2ME(2) abrogates TGF-ß3-induced expression of Col I(αI), Col III(αI), PAI-1, CTGF, and α-SMA. Molecularly, 2ME(2) ameliorates TGF-ß3-induced Smad2/3 phosphorylation and nuclear translocation. In addition, 2ME(2) inhibits TGF-ß3-induced activation of the PI3K/Akt/mTOR pathway. CONCLUSION(S): TGF-ß3-induced profibrotic response in fibroid cells is mediated by Smad-dependent and Smad-independent PI3K/Akt/mTOR pathways. 2ME(2) inhibits TGF-ß3 profibrotic effects in huLM cells by ameliorating both Smad-dependent and Smad-independent signaling pathways.