The Potential of Transforming Growth Factor-beta Inhibitor and Vascular Endothelial Growth Factor Inhibitor as Therapeutic Agents for Uterine Leiomyoma

Background: Uterine leiomyoma is the most common benign tumor in women of reproductive age, and it can cause infertility. The growth of uterine leiomyoma is mediated by various steroids and growth factors. The purpose of this study was to evaluate the expression of various growth factors in uterine leiomyoma. Additionally, comparing the effects of existing medication and specific growth factor inhibitors on leiomyoma and the normal myometrium, we aimed to see the potential of transforming growth factor-beta (TGF-β) inhibitors and vascular endothelial growth factor (VEGF) inhibitors as therapeutic drugs for uterine leiomyoma. Methods: This in vitro study included uterine leiomyoma samples from 12 patients who underwent hysterectomy by laparoscopy or laparotomy at Seoul St. Mary's Hospital between May 2016 and March 2018. Normal myometrium and uterine leiomyoma tissue were obtained from each patient and the expression of growth factors was compared using immunohistochemical staining. After the primary culture of normal myometrial and leiomyoma cells, cell viability was evaluated following treatment with 100 nM ulipristal acetate (UPA) and mifepristone for 48 h. Western blot analysis was performed to determine the protein expression of each growth factor. Cell viability was determined following treatment with a 10-µM TGF-β inhibitor (LY364947) and a 5-µM VEGF inhibitor (axitinib) for 24 h in cultured normal myometrium and leiomyoma cells. Results: Immunohistochemical staining revealed the significantly higher intensity of TGF-β and VEGF in the leiomyoma tissue than in the normal myometrium (P < 0.05). Mifepristone treatment decreased VEGF expression by 62% in the leiomyoma cells (P < 0.05). According to the cell counting kit-8 (CCK-8) assay, cell viability was decreased after UPA, mifepristone, TGF-β1 inhibitor, and VEGF inhibitor treatments in the normal myometrium and leiomyoma tissue. The effects of the TGF-β1 inhibitor significantly differed between normal myometrium and leiomyoma tissue, with a greater decrease in cell survival in the leiomyoma tissue (P < 0.05). Post-hoc analysis showed that the TGF-β1 and VEGF inhibitors had a greater inhibitory effect on leiomyoma tissue compared with that of UPA. Conclusion: TGF-β and VEGF inhibitors significantly decreased the viability of uterine leiomyoma cells, showing stronger effects than the conventional drug, UPA. TGF-β1 inhibitors affect both leiomyoma tissue and the normal uterus; thus, targeted local treatment rather than systemic treatment should be considered.