Effects of Medroxyprogesterone Acetate on Gene Expression in Myometrial Explants from Pregnant Women

Abstract

Context: Progesterone is important physiologically and therapeutically to maintain uterine quiescence during pregnancy, in part through controlling myometrial gene expression. Objective: The objective of the study was to use expression microarray and quantitative reverse transcriptase-PCR (qRT-PCR) validation to determine the changes in gene expression induced by prolonged exposure of human myometrium to a synthetic progestogen. Design: Myometrial explants, obtained at elective cesarean section (n = 9), were maintained in culture, under 0.6 g tension, for 65 h in the presence of medroxyprogesterone acetate (100 nm) or vehicle. Expression array was performed using Illumina beadchip arrays. Approximately 30% of differentially expressed transcripts were validated in biological replicates (n = 10) by qRT-PCR. Results: The 114 significantly regulated transcripts were significantly enriched in inflammatory response (P = 0.00001), growth factor activity (P = 0.0004), and cytokine activity genes (P = 0.008). Thirty-four transcripts were validated using qRT-PCR in explants obtained from 10 further women. There was very close agreement in the fold changes obtained by array and qRT-PCR (r2 = 0.9, P < 0.0001). We confirmed significant down-regulation of a number of genes that have been well characterized as progesterone sensitive (IL-1B, IL-6, PTGS2, and GJA1). However, the top and sixth most down-regulated transcripts encoded two cytokines, IL-11 and IL-24, respectively, not previously implicated in mediating the effects of progesterone in myometrium. Both were validated by qRT-PCR (4.3- and 2.2-fold down-regulated, both P < 0.001). Conclusions: Medroxyprogesterone acetate controls expression of multiple genes in myometrium, including many that have not previously been characterized as progestogen regulated in this tissue, including IL-11 and IL-24. It is plausible that proteins encoded by some of these genes may have important but as yet uncharacterized effects in controlling human parturition.