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

Abstract

Progesterone is important physiologically and therapeutically to maintain uterine quiescence during pregnancy, in part through controlling myometrial gene expression. 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. 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. 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). 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.