Ulipristal Acetate and Extracellular Matrix Production in Human Leiomyomas In Vivo: A Laboratory Analysis of a Randomized Placebo Controlled Trial

Abstract

In a prior randomized controlled study, patients treated with ulipristal acetate (UPA) or placebo for 3 months had a decrease in leiomyoma size. A total of 10 patients' tissue samples (5 placebo and 5 treated with 10 mg/d UPA) that underwent hysterectomy and tissue preservation were identified from this study. Quantitative real-time reverse transcriptase polymerase chain reaction and Western blotting were used to assess fold gene and protein expression of extracellular membrane (ECM) proteins: collagen 1A (COL1A), fibronectin (FN1), and versican (VCAN) of the samples. Confirmatory immunohistochemical analysis was performed. Changes in total matrix collagen were examined using Masson trichrome staining. Multiplex measurement of the matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases was performed. Compared to placebo-treated surgical specimens, 80% of the treated specimens showed decrease in VCAN protein, 60% showed decrease in FN1, but no consistent alteration in COL1A. This effect was also supported by immunohistochemistry where leiomyoma surgical specimens demonstrated decreased amount of FN1 and VCAN on UPA treatment. Increased MMP2 and decreased MMP9 in treated patient leiomyomas indicate both degradation of the matrix and inhibition of the pathway involved in matrix production. Treatment with UPA decreased fibroid volume in placebo-controlled, randomized trials. Treatment with UPA decreased gene expression and protein production in leiomyoma tissue, suggesting both an impact on water content and ECM protein concentration as a mechanism of ulipristal-mediated decrease in leiomyoma size.

Keywords: collagen-1; extracellular matrix; leiomyoma; ulipristal acetate; versican.

Figure 1.

Immunoreactivity of extracellular membrane (ECM) proteins in leiomyoma tissue. A, Collagen 1A (COL1A): There is no change in the expression of COL1A in treated (6-10) leiomyoma tissue samples when compared to placebo samples (1-5). B, Fibronectin: Immunoreactivity for fibronectin (FN1) protein is decreased in treated patient samples (6-10). C, Versican: Treated samples (6-10) show a decrease in versican (VCAN) protein expression. D, Masson trichrome stain of leiomyoma tissue from placebo (patients 1-5) and ulipristal acetate (UPA)-treated (patients 6-10) specimen revealed less collagen production within the ECM of treated samples as indicated by the blue staining with aniline blue. These are the representative slides from a total of 4 staining protocols (×20).

Figure 2.

The box whisker plot compares protein amount in ulipristal acetate (UPA)-treated leiomyomas from patients (T; n = 6) to fibroids from placebo patients (P; n = 8). The Bio-Plex Pro Human matrix metalloproteinase (MMP) assay kit was used to analyze expression of MMPs (1-3, 7-10, 12, and 13); MMP1, MMP2, MMP7, and MMP9 demonstrated significant differences in leiomyoma tissue from UPA-treated patients compared to placebo. The experiment was conducted twice with a minimum of 3 replicates per sample.*Significant difference (P < .05), UPA-treated leiomyoma compared to placebo.