Transforming growth factor-beta3 is expressed at high levels in leiomyoma where it stimulates fibronectin expression and cell proliferation.

OBJECTIVE: To investigate the expression of TGF-beta3 in leiomyoma and myometrium as well as the effect of TGF-beta3 on the expression of fibronectin and on the proliferation of leiomyoma and myometrial cells.
DESIGN: Observational and in vitro experimental study.
SETTING: University medical center. PATIENT(S): Women with (n = 18) leiomyoma. INTERVENTION(S): First TGF-beta3 mRNA and protein levels in myometrium and leiomyoma were measured, and then myometrial and leiomyoma cells in culture were treated with TGF-beta3. MAIN OUTCOME MEASURE(S): TGF-beta3 and fibronectin mRNA were evaluated by Northern analysis. Myometrial and leiomyoma cell proliferation was assessed with use of [(3)H]thymidine incorporation. RESULT(S): The TGF-beta3 mRNA level in the leiomyoma samples was 3.5-fold higher than in the myometrial samples. The highest TGF-beta3 mRNA level was observed in leiomyoma samples from midsecretory phase and was 5-fold higher than in proliferative phase samples. Fibronectin mRNA expression also was higher in the leiomyoma than in the myometrium. TGF-beta3 induced fibronectin expression in leiomyoma cells and directly stimulated myometrial and leiomyoma cell proliferation in cultures. CONCLUSION(S): These findings suggest that TGF-beta3 may be mediating the growth-promoting effects of sex steroids on leiomyomas by playing a role in the fibrogenic process and cell proliferation that characterize these tumors.