Recombinant H2 relaxin inhibits apoptosis and induces cell proliferation in cultured leiomyoma cells without affecting those in cultured normal myometrial cells.

OBJECTIVE: To evaluate the effects of human relaxin on proliferation and apoptosis in cultured human uterine leiomyoma cells and normal myometrial cells. DESIGN: In vitro experiment. SETTING: Research laboratory at Kobe University Graduate School of Medicine. PATIENT(S): Nine patients undergoing hysterectomy for uterine leiomyoma. INTERVENTION(S): Cultured leiomyoma cells and normal myometrial cells were treated with human recombinant (rH2) relaxin. MAIN OUTCOME MEASURE(S): Human relaxin receptor LGR7 expressions in cultured leiomyoma cells and myometrial cells were evaluated by immunocytochemical staining. Cell proliferation, proliferating cell nuclear antigen-positive rate, and TUNEL-positive rate were assessed by MTS assay, immunocytochemistry, and TUNEL assay, respectively. Caspase-3 expression was evaluated by Western blot analysis. RESULT(S): LGR7 expression was observed both in cultured human leiomyoma cells and myometrial cells. Compared with untreated control cultures, treatment with rH2 relaxin increased the number of viable cultured leiomyoma cells and the proliferating cell nuclear antigen-positive rate in those cells but not in myometrial cells. Moreover, treatment with rH2 relaxin decreased the TUNEL-positive rate in cultured leiomyoma cells but not in myometrial cells. Similarly, Western blot analysis revealed that treatment with rH2 relaxin decreased the expression of caspase-3 in cultured leiomyoma cells but not in myometrial cells. CONCLUSION(S): These results suggest that rH2 relaxin selectively inhibits apoptosis by down-regulating caspse-3 expression and induces proliferation in cultured human leiomyoma cells without affecting apoptosis or proliferation in normal myometrial cells.