Inhibitory effects of Scutellaria barbata D. Don on human uterine leiomyomal smooth muscle cell proliferation through cell cycle analysis.

Scutellaria barbata D. Don (SB) is one of the herbs belonging to perennial plants, which is known in traditional Korean medicine as 'Ban-Ji-Ryun,' and has been used as an anti-inflammatory and anti-tumor agents against human uterine leiomyoma, mammalian and ovarian cancers. Although the difference between uterine smooth muscle cell (SMC) and leiomyomal SMCs has not been clearly established, the action of SB water extract was investigated using SMCs from normal myometrium and leiomyoma. The proliferation of cultured myometrial and leiomyomal SMC was inhibited by SB treatment. Flow cytometric analysis showed that the population in the G1 phase of the cell cycle increased under SB treatment. Western blotting analysis showed that markers of SMC differentiation such as alpha-smooth muscle actin (alpha-SMA), calponin h1 and cyclin-dependent kinase inhibitor p27 were induced by treatment with SB in myometrial and leiomyomal SMCs. In contrast, cell-cycle-related gene products from the G1 phase of the cell cycle, such as cyclin E and cdk2, were not affected. Taken together, these results indicate that SB inhibits the proliferation of myometrial and leiomyomals SMC through the induction of alpha-SMA, calponin h1 and p27. It is suggested that SB may induce differentiation in uterine SMC and may influence tissue remodeling and reconstruction during physiological and pathophysiological events.