Quantitative expression of growth regulatory genes in endometrium from women with and without endometriosis

Abstract

Our previous investigations have demonstrated that endometrial cells from women with endometriosis are resistant to spontaneous and induced apoptosis in comparison with endometrial cells from control subjects without endometriosis. The objective of this study was to measure the expression of mRNA for selected proapoptotic and anti-apoptotic genes in eutopic endometria from women with and without endometriosis. The expression of mRNA for the apoptosis regulating genes: BCL-xS; BCL-xL; p53; DAD; and BAD were measured by quantitative, reverse transcriptase, polymerase chain reaction assay (rt-pcr) in endometrial cells obtained from women with and without endometriosis at different phases of the menstrual cycle. Endometrial cells from eutopic endometrial biopsies from women with (n=7) and without (n=4) endometriosis were prepared by digestion with collagenase/DNase. Total RNA was extracted with RNAsol, cDNA prepared, and mRNA for apoptotic regulating genes quantitated by the START-pcr method. The results for each gene were expressed relative to 1 million beta-actin mRNA molecules. Results were compared between women with and without endometriosis for different phases of the menstrual cycle. The ratio of mRNA expression for the anti-apoptotic gene, BCL-xL and the pro-apoptotic gene, BCL-xS (BCL-xL:BCL-xS) was > 1 in women with endometriosis, but < 1 in controls during the mid-proliferative through mid secretory phase of the menstrual cycle. This ratio was < or = to 1.0 during the other phases of the cycle for both groups. Expression of the pro-apoptotic genes, BAD (BCL antagonist) and p53 were comparable for both groups during the proliferative phase of the cycle, but were increased (2–5 fold) in endometrial cells from controls during the mid-late secretory phase without changing during this phase for women with endometriosis. Expression of the anti-apoptotic gene, DAD (defender against cell death) was also comparable for both groups during the proliferative phase of the cycle, but increased by 5–10 fold in endometrial cells from women with endometriosis during the late secretory phase of the cycle while the levels of this gene did not change during this phase for controls. The results of these studies provide genomic evidence for the relative resistance to apoptosis that we and others have reported for the endometrium of women with endometriosis. The differences in expression of apoptotic regulatory genes were most apparent during the mid-late secretory phase of the menstrual cycle which parallels results that we have reported previously using the TUNEL assay to measure apoptosis. The results are consistent with an intrinsic capacity of endometrial cells from women with endometriosis to resist normal homeostatic mechanisms and to establish ectopic sites of growth which are the hallmark of the disease.