Increased expression of c-fos protein associated with increased matrix metalloproteinase-9 protein expression in the endometrium of endometriotic patients

Objective: To investigate c-fos and matrix metalloproteinase-9 (MMP-9) expression in the endometrium from women with or without endometriosis throughout the menstrual cycle, and to explore the correlation of c-fos expression with MMP-9 expression and 17 beta-E-2 levels in serum. Design: Molecular studies in human tissue. Setting: A women's hospital in China. Patient(s): Fifty-five premenopausal women (25 with endometriosis and 30 without endometriosis) undergoing laparoscopic surgery or hysterectomy. Intervention(s): Eutopic and ectopic endometrium tissue were obtained at the time of surgery. Peripheral sera were also collected on the same day. Main Outcome Measure(s): Immunohistochemical localization of c-fos in the endometrium, c-fos and MMP-9 protein levels in the endometrium, and 17 beta-E-2 levels in the serum. Result(s): c-fos protein was predominantly located in the nuclei of glandular epithelial cells and stromal cells. c-fos and MMP-9 protein levels in paired eutopic and ectopic endometria from women with endometriosis were significantly higher than those in the endometrium from women without endometriosis. No significant difference in c-fos or MMP-9 protein levels was observed between paired eutopic and ectopic endometria. c-fos protein levels in endometrium positively correlated with endometrial MMP-9 levels and serum 17 beta-E-2 levels. Consclusion(s): Expression of c-fos in the human endometrium may be regulated by 17 beta-E-2, and c-fos may be involved in development of endometriosis by promoting MMP-9 gene expression and subsequently the invasive potential of endometrial explants.