Simvastatin Inhibits Wnt/β-Catenin Pathway in Uterine Leiomyoma

The Wnt/β-catenin pathway is upregulated in uterine leiomyomas, the most common benign tumors in the female reproductive tract. Simvastatin is an antihyperlipidemic drug, and previous in vitro and in vivo reports showed that it may have therapeutic effects in treating leiomyomas. The objective of this study was to examine the effects of simvastatin on the Wnt/β-catenin signaling pathway in leiomyoma. We treated primary and immortalized human leiomyoma cells with simvastatin and examined its effects using quantitative real-time polymerase chain reaction, Western blotting, and immunocytochemistry. We also examined the effects using human leiomyoma tissues from an ongoing randomized controlled trial in which women with symptomatic leiomyoma received simvastatin (40 mg) or placebo for 3 months prior to their surgery. The results of this study revealed that simvastatin significantly reduced the expression of Wnt4 and its co-receptor LRP5. After simvastatin treatment, levels of total β-catenin and its active form, nonphosphorylated β-catenin, were reduced in both cell types. Additionally, simvastatin reduced the expression of Wnt4 and total β-catenin, as well as nonphosphorylated β-catenin protein expression in response to estrogen and progesterone. Simvastatin also inhibited the expression of c-Myc, a downstream target of the Wnt/β-catenin pathway. The effect of simvastatin on nonphosphorylated-β-catenin, the key regulator of the Wnt/β-catenin pathway, was recapitulated in human leiomyoma tissue. These results suggest that simvastatin may have a beneficial effect on uterine leiomyoma through suppressing the overactive Wnt/β-catenin pathway.