Progesterone Inhibition of Wnt/β-Catenin Signaling in Normal Endometrium and Endometrial Cancer

Abstract

Purpose. Wnt signaling regulates the fine balance between stemness and differentiation. Here, the role of Wnt signaling to maintain the balance between estrogen-induced proliferation and progesterone-induced differentiation during the menstrual cycle, as well as during the induction of hyperplasia and carcinogenesis of the endometrium, was investigated. Experimental Design: Endometrial gene expression profiles from estradiol (E 2 ) and E 2 + medroxyprogesterone acetate-treated postmenopausal patients were combined with profiles obtained during the menstrual cycle (PubMed; GEO DataSets). Ishikawa cells were transfected with progesterone receptors and Wnt inhibitors dickkopf homologue 1 (DKK1) and forkhead box O1 (FOXO1), measuring Wnt activation. Expression of DKK1 and FOXO1 was inhibited by use of sequence-specific short hairpins. Furthermore, patient samples (hormone-treated endometria, hyperplasia, and endometrial cancer) were stained for Wnt activation using nuclear β-catenin and CD44. Results: In vivo, targets and components of the Wnt signaling pathway (among them DKK1 and FOXO1) are regulated by E 2 and progesterone. In Wnt-activated Ishikawa cells, progesterone inhibits Wnt signaling by induction of DKK1 and FOXO1. Furthermore, using siRNA-mediated knockdown of both DKK1 and FOXO1, progesterone inhibition of Wnt signaling was partly circumvented. Subsequently, immunohistochemical analysis of the Wnt target gene CD44 showed that progesterone acted as an inhibitor of Wnt signaling in hyperplasia and in well-differentiated endometrial cancer. The female sex hormones estradiol (E 2 ) and progesterone play rate-limiting roles in the cyclical renewal of the inner layer of the uterus (endometrium). In the first half of the regular menstrual cycle, the proliferation phase, E 2 is required to expand the endometrial layer by inducing cell proliferation. In the second half of the menstrual cycle, the secretory phase, progesterone levels increase, which antagonizes the proliferative activity of E 2 by inducing differentiation of epithelial and stromal cells of the endometrium (1). Thus, inhibition of E 2 -induced proliferation by progesterone is crucial for the maintenance of homeostasis in the endometrium.Increased estrogen signaling often underlies endometrial hyperplasia and is a well-established risk factor for endometrial cancer (2). Because progesterone inhibits estrogen-induced endometrial proliferation, progesterone has been used in its synthetic form [i.e., medroxyprogesterone acetate (MPA)] in palliative treatment of advanced and recurrent endometrial cancer with modest though significant response rates (15-25%; ref. 3). Progesterone has also been used as a primary treatment for endometrial carcinoma confined to the endometrial layer of the uterus, for example, in premenopausal women determined to preserve fertility. Response rates in these women can be up to 60% (4, 5), indicating that progesterone signaling in well-differentiated endometrial cancer is a potent inhibitor of endometrial carcinogene...

Comparison of the Effects of Early Pregnancy with Human Interferon, Alpha 2 (IFNA2), on Gene Expression in Bovine Endometrium1

“…For dickkopf homolog 1 (DKK1), coding for an inhibitor of WNT signaling, mRNA expression was found in stromal cells on D16 and D19 of pregnancy. This finding is in line with those studies in human endometrium, in which induction of DKK1 expression by P4 [76] and specific expression during the window of implantation [77] have been shown.…”

Regulation of the hyaluronan system in ovine endometrium by ovarian steroids

“…The expression of the three HAS isoforms is organ-and cell-specific (Spicer & McDonald 1998, Pienimaki et al 2001, Straach et al 2005. They are differentially regulated by various stimuli, suggesting distinct functional roles of the three proteins (Wang et al 2009). Nevertheless, changes in the transcriptional levels of HAS mRNA do not always correlate with changes in the synthesis of HA (Recklies et al 2001) due to posttranscriptional modification (Tammi et al 2002).…”

Immunolocalization of E-cadherin and β-catenin in the cyclic and early pregnant canine endometrium

“…The Wnt/Wg signaling pathway has been demonstrated to be present in the endometrium [30,54], and β-catenin is involved in such mechanisms [29].…”

“…Such a strong supra-nuclear immunolabeling might be associated with a transitory stimulation of the Wnt signaling pathway, in non-pregnant endometrium, as it clearly contrasts to the usual β-catenin cytoplasmic immunostaining. As a consequence, the Wntassociated pathways, demonstrated in humans to be dependent on high levels of estrogens and on cell proliferation [30], might also be activated in the canine endometrium during estrus.…”

“…In the cytoplasm, β-catenin pairs bind strongly to the E-cadherin domain, binding the complex to the actin skeleton through the α-actin molecule [25][26][27]. In addition to its role in cell-to-cell adhesion, β-catenin also plays an important role in the Wnt/Wg growth factor signaling pathway [28,29], which has been implicated in the regulation of the endometrial cycle [30] and in implantation [31].…”