Vitamin D inhibits myometrial and leiomyoma cell proliferation in vitro

Objective: To determine the effect of 1,25(OH)(2)D-3 and 25(OH)D3 vitamin D derivates on the growth of leiomyoma and myometrial cells in vitro. Design: In vitro study. Setting: Cell biology research laboratory. Patient(s): Six premenopausal women with uterine leiomyomas undergoing hysterectomy. Intervention(s): Samples of leiomyomas and normal myometrial tissue were obtained, and paired cultures were established. Main Outcome Measure(s): A colorimetric crystal violet assay to determine the effect of 1,25(OH)2D3 and 25(OH)D3 on cell growth. Result(s): In both myometrial and leiomyoma cells, 0.1 nM physiologic level of 1,25(OH)(2)D-3 inhibited growth by 12% when compared with controls. The growth inhibition was concentration dependent; the highest concentration of 1,25(OH)(2)D-3 (100 nM) inhibited growth by 62% in both cell types. All the differences were statistically significant. A slight stimulation (<4%) of cell proliferation was observed with the lowest 25(OH)2D3 concentrations. When treated with either a 500 nM or 1000 nM concentration of the compound, the growth of both cell types fell to approximately 50% of that of the control cultures, and the level of inhibition with the latter concentration was statistically significant. Conclusion(S): Both myometrial and leiomyoma cell growth in vitro was effectively inhibited by 1,25(OH)(2)D-3. Vitamin D may play a role in the growth of uterine leiomyomas. (Fertil Steril (R) 2009;91:1919-25. (C) 2009 by American Society for Reproductive Medicine.)