Relugolix reduces leiomyoma extracellular matrix production via the transforming growth factor-beta pathway.

Objective: To determine if the oral gonadotropin-releasing hormone antagonist relugolix affects leiomyoma extracellular matrix production through the transforming growth factor-beta (TGF-β) pathway.

Design: Laboratory study.

Subjects: None.

Exposure: Exposure of human leiomyoma cells to TGF-β and/or relugolix.

Main outcome measures: Production of TGF-β, pSMAD2/3, SMAD2/3, collagen 1A1 (COL1A1), fibronectin (FN1), and versican (VCAN) in treated and untreated leiomyoma cells.

Results: Transforming growth factor-beta 3 production decreased at 24 hours with relugolix 10 nM (0.80 ± 0.09-fold) and 100 nM (0.86 ± 0.06-fold) and at 48 hours with relugolix 1 nM (0.86 ± 0.05-fold) and 100 nM (0.86 ± 0.06-fold). pSMAD2/3 production decreased at 24 hours with relugolix 1 nM (0.71 ± 0.01-fold), 10 nM (0.68 ± 0.01-fold), and 100 nM (0.41 ± 0.10-fold). Compared with relugolix treatment alone at the same concentration, combination treatment at 24 hours resulted in significantly increased COL1A1, FN1, and VCAN production with relugolix 1 nM, 10 nM, and 100 nM. At 48 hours, combination treatment resulted in significantly increased COL1A1, FN1, and VCAN production with relugolix 10 nM and 100 nM.

Conclusion: Relugolix regulated leiomyoma size by decreasing COL1A1, FN1, and VCAN production. This effect is at least partly through the TGF-β pathway.