Abstract
OBJECTIVE: To investigate the regulation of early growth response-2 (Egr-2) by transforming growth factor β3 (TGF-β3) and its functions in cultured human uterine leiomyoma smooth muscle cells. DESIGN: Laboratory research. SETTING: Academic medical center. PATIENT(S): Primary leiomyoma cells from patients with symptomatic leiomyomata. INTERVENTION(S): Tissue culture followed by RNA and protein analysis. MAIN OUTCOME MEASURE(S): Cell proliferation, alteration in extracellular matrix component expression. RESULT(S): In vivo mRNA levels of Egr-2 were statistically significantly higher in leiomyoma tissues compared with matched myometrial tissues, and showed a statistically significant correlation with TGF-β3 messenger RNA (mRNA) levels in leiomyoma tissues. In primary leiomyoma smooth muscle cells, TGF-β3 statistically significantly induced Egr-2 gene expression in a dose-dependent and time-dependent manner. Small interfering RNA (siRNA) knockdown of Egr-2 markedly increased the level of the proliferation marker proliferating cell nuclear antigen and the expression of proto-oncogene c-myc. On the other hand, ablation of Egr-2 stimulated collagen-1A1 and collagen-3A1 transcription and inhibited dermatopontin gene expression. However, the mRNA levels of α-smooth muscle actin and fibronectin were not affected by Egr-2 knockdown. CONCLUSION(S): We demonstrated that TGF-β3 regulated Egr-2 gene expression and presented evidence that Egr-2 decreases collagen production and stimulates dermatopontin gene expression.