2-methoxyestradiol causes functional repression of transforming growth factor-β3 signaling by ameliorating Smad and non-Smad signaling pathways in immortalized uterine fibroid cells

Capsule:
The profibrotic response of transforming growth factor (TGF) b3 in fibroid cells is mediated by Smad-dependent and Smad-independent PI3K/Akt/mTOR pathways. 2-Methoxyestradiol inhibits TGF-b3 profibrotic effects in fibroid cells by ameliorating both Smad-dependent and Smad-independent signaling pathways.

Authors:
Salama A. Salama, Ph.D., Concepcion R. Diaz-Arrastia, M.D., Gokhan S. Kilic, M.D., Marwa W. Kamel, M.Sc.
Volume 98, Issue 1 , Pages 178-184.e1, July 2012

Objective:
To investigate the effects and the mechanism of action of 2-methoxyestradiol (2ME2) on transforming growth factor (TGF) β3–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-β3 (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 2ME2 (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 2ME2 on Smad-microtubule binding was evaluated by coimmunoprecipitation.

Result(s):
Our data revealed that TGF-β3–induced fibrogenic response in huLM is mediated by both Smad-dependent and Smad-independent PI3K/Akt/mTOR signaling pathways. 2ME2 abrogates TGF-β3–induced expression of Col I(αI), Col III(αI), PAI-1, CTGF, and α-SMA. Molecularly, 2ME2 ameliorates TGF-β3–induced Smad2/3 phosphorylation and nuclear translocation. In addition, 2ME2 inhibits TGF-β3–induced activation of the PI3K/Akt/mTOR pathway.

Conclusion(s):
TGF-β3–induced profibrotic response in fibroid cells is mediated by Smad-dependent and Smad-independent PI3K/Akt/mTOR pathways. 2ME2 inhibits TGF-β3 profibrotic effects in huLM cells by ameliorating both Smad-dependent and Smad-independent signaling pathways.

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