Progesterone Up-Regulates WT1 mRna and Protein, and Alters the Relative Expression of WT1 Transcripts in Cultured Endometrial

OBJECTIVE: To determine the change in expression of the Wilms tumor suppressorgene product, J4/T1, by progesterone alone in endometrial stromal cell culture and to study its relationship with prolactin, a marker of decidualization. In addition, to examine the change in ratio of H14T isoforms with and without exon 5 message. METHODS: Endometrial biopsies were taken from eight patients who had hysterectomy. Stromal cells were isolated and cultured in the presence ofprogesterone alone (12 days) or progesterone and 8-bromo-cyclic adenosine monophosphate (cAMP) (6 days). RNA was extracted from cells, and reverse transcription, real-time polymerase chain reaction (PCR), and conventional PCR were done to analyze 1/T1 mRNA expression. Immunocytochemistry was performed on equivalent cells to study WT1 protein expression. Decidualization was identfied by increased prolactin concentrations in the media and immunocytochemical markers IGFBP- 1 and collagen IV. RESULTS: Reverse transcription and real-time PCR revealed a significant increase in 14/T1 mRNA with increasing progesterone concentrations when decidualization was occurring (n = 6, P = 002). Increasing progesterone concentrations also increased the proportion of the WT1 transcript containing a 1 7-amino-acid insert (+ exon 5 expression); changes in H14T exon 5 expression have been shown to be involved in control ofproliferation and differentiation. Si nificant correlations between WT1 message and prolactin existed at physiologic progesterone concentrations (6.25, 12.5, 25, and 50 nM; P <.05) until prolactin concen-trations reached a plateau at 100 nM. At concentrations ofprogesterone alone (> 25 nM) and progesterone with 8-bromo-cAMP, 1/T1 protein was localized to the nuclei of many of the decidualized stromal cells. CONCLUSION: The changing expression of WT1 isoforms in endometrial stromal cells caused by progesterone may be importantfor differentiation into the decidualized phenotype. ( Soc Gynecol Investi