Expression of Wnt-Signaling Pathway Genes and Wnt-Target Genes in Human Endometriosis Tissue [25]

INTRODUCTION: Endometriosis affects approximately 10–15% of reproductive-aged women. The disease is characterized by functional endometrial glands outside the uterine cavity; peritoneal, ovarian, and deep infiltrating endometriosis lesions can be distinguished. Epithelial-mesenchymal transition describes the conversion of stationary epithelial cells into proliferative and invasive mesenchymal cells. The canonical Wnt-signaling system serves as an important driver for epithelial-mesenchymal transition. Hence, it was the study objective to quantify the expression changes of 1) Wnt-signaling pathway genes and 2) Wnt-target genes—also playing a role in epithelial-mesenchymal transition—in endometriosis tissues. METHODS: Real-time polymerase chain reaction was applied to 77 tissue samples collected from reproductive-aged women with and without endometriosis in different stages of their cycles. RESULTS: In the endometria of those in the case and control groups, expression of Wnt agonists was significantly increased in the luteal compared with the follicular phase of the cycle. Levels of Wnt-signaling receptors were down-regulated in the endometria of endometriosis patients compared with those in the control group. In ovarian endometriosis, the expression of Wnt-signaling agonists, antagonists, and receptors as well as Wnt-target genes relevant in epithelial-mesenchymal transition was significantly altered when compared with matching endometrial samples. CONCLUSION: The expression of endometrial Wnt-signaling genes varies in different phases of the cycle; the expression pattern differs between those with and without endometriosis. Expression of genes encoding for the Wnt-signaling system as well as Wnt-target genes involved in epithelial-mesenchymal transition is regulated differently in endometriosis and endometrium. Therefore, we hypothesize that altered Wnt-signaling may result in epithelial-mesenchymal transition of endometriosis cells, serving as prerequisite for the establishment and maintenance of ectopic lesions.