The Expression Of DNMT1,HDAC1 And PR In Endometriosis

BackgroundEndometriosis is defined as the presence of viable endometrial tissue outside of the uterine cavity.It is a common gynecologic disease, affecting about 10-15%women in the reproductive age group and its morbidity has increased in recent years.Endometriosis is associated with severely painful menstruation,chronic pelvic pain,and infertility.A variety of theories have been proposed to account for this susceptibility, including retrograde menstruation with transport of endometrial cells, metaplasia of coelomic epithelium,hematogenous or lymphatic spread of endornetrial cells,aberrant immunologic response and an altered peritoneal environment and so on.But the precise pathogenesis mechanism is unclear.Resent studies show that the development of endornetriosis is related to epigenetics.Epigenetics is defined as the investigation of heritable changes in gene expression that occur without changes in DNA sequence.Epigenetic regulatory mechanisms include DNA methylation,histone modifications and gene imprinting.DNA methylation is a crucial epigenetic modification of the genome that plays an important role in the regulation gene expression and genomic imprinting,cell differentiation,and regulation of many of cellular processes.DNA methyltransferases (DNMTs)is the key enzymes of DNA methylation,it catalyze the transfer of methyl group from S-adenosyl -L-methionine to the 5'position of a cytosine nucleotide adjacent to guanine(C_pG)in DNA strand,which usually act as transcriptional repressors in expression regulation of a number of genes.DNMTs include DNMT1,DNMT3A and DNMT3B. DNMT1 is one of the first discovered DNMTs and its level can indirectly reflect the level of DNA methylation in whole genome.DNMT1 is often viewed as a "maintenance" methyltransferase;DNMT3A and 3B are viewed as de novo ones.Histone modifications include acetylation,methylation, phosphorylation and ubiquityination.The histone acetylation is important mechanisms of gene regulation.The level of histone acetylation depends on the activity of two families of enzymes,histone acetyltransferases (HATs)and histone deacetylases(HDACs).Mammalian HDACs have been grouped into three classes according to their homology to yeast proteins.HDAC1(1996)belongs to the classⅠfamily and is the representative enzymes of HDACs.HDAC1 can lead to transcriptional repressor of genes that are involved in the control of cell-cycle progression,proliferation,differentiation and apoptosis.As reported before,DNMT1 and HDAC1 were aberrant expressed in many kind of cancer.Even though endometriosis is considered a benign disorder,it exhibits some characteristics of malignancy that also are seen in malignant lesions,such as cellular atypical hyperproliferation,invasion, metastasis,neoangiogenesis and genomic instability.A relationship between endometriosis and cancer has been accepted.But little is known about the expression of DNMT1 and HDAC1 in endometriosis.Molecular observations support that endometriosis has the characters of steroid-dependence.Progesterone plays an important role in the regulation of normal endometrium function by binding to progesterone receptor(PR).The expression of PR may be related to the endometriosis-associated infertility and "progesterone resistance".ObjectiveTo investigate the possible roles of DNMT1,HDAC1 and PR playing in the pathogenesis and development of endometriosis by detecting the expression in the ectopic and the eutopic endometrium from women with and without endometriosis.Materials and methodsTwenty specimens of ectopic endometrium tissues and twenty specimens of eutopic endometrium tissues were obtained from patients with endometriosis.Twenty specimens of endometrium form women without endometriosis were used as control group. Immunohistochemistry and western blotting were employed to examine the localizations and the expression levels of DNMT1 and HDAC1. Immunohistochemistry was employed to examine the expression of PR.Results1.DNMT1 was located in the nucleus of epithelial and stromal cells. The DNMT1 protein expression score in eutopic endometrium of the endornetriosis patients was 3.90±1.92,significantly higher than that in the control group(2.0±0.97),P<0.01.In western blotting,semi-quantitative analysis showed that the relative expression of DNMT1 protein in eutopic and ectopic endometrium of the endometriosis was significantly higher than that in the control group.(1.86±0.75,2.14±0.93 VS 1.13±0.43,P< 0.01,P<0.01).But no significant difference was found between eutopic and ectopic endometrium.(P>0.05).In eutopic endometrium,the relative expre ssion of DNMT1 protein in secretory phase of the endometriosis was s ignificantly higher than that in the proliferative phase(2.34±0.85 VS 1.52±0.46,P<0.05).2.HDAC1 was located in the nucleus of epithelial and stromal cells. The HDAC1 protein expression score in eutopic endometrium of the endometriosis patients was 4.40±1.60,significantly higher than that in the control group(2.65±1.84),P<0.01.In western blotting,semi-quantitative analysis showed that the relative expression of HDAC1 protein in eutopic and ectopic endometrium of the endometriosis was significantly higher than that in the control group.(2.67±0.69;2.55±1.36 VS 1.63±0.93,P< 0.01,P<0.05).But no significant difference between eutopic and ectopic endometrium(P>0.05).In eutopic endometrium,although the HDAC1 expression level in the secretory phase was higher than that in the proliferative phase,the difference did not reach statistical significance(2.93±0.70 VS 2.52±0.68,P>0.05).3.PR was expressed in the endometrial glandular epithelium and stromal cells.In proliferative phase,the mean score of expression of PR was(3.07±1.10)in eutopic endometrium of endometriosis,lower than that in the control endometrium(4.20±1.40)(P<0.05)Conclusion1.DNMT1,HDAC1and PR were located in the nucleus of cells.2.DNMT1 protein expression was found to be significantly increased in eutopic and ectopic endometrium with endometriosis in comparison with control group.There was no significant difference between eutopic and ectopic endometrium.The expression of DNMT1 protein in secretory phase of the endometriosis was significantly higher than that in the proliferative phase.3.HDAC1 protein expression was found to be significantly increased in eutopic and ectopic endometrium with endometriosis in comparison with control group,and there was no significant difference between eutopic and ectopic endometrium.The HDAC1 expression level was no significant difference between in the secretory and proliferative phase of the endometriosis.4.The expression of PR in eutopic endometrium with endometriosis was lower than that in the control group.5.The changes of expression levels of the DNMT1,HDAC1 and PR in eutopic endometrum with endometriosis imply that eutopic endometrum differ from normal endometrium,which may play an important role in the pathophysiology and development of endometriosis.