The Detection Of Methylation Of IGFBP-rP1 Gene And The Relationship With Its MRNA And Protein Expression In Endometrial Adenocarcinoma Tissues

Background and ObjectiveEndometrial carcinoma, a group of epithelial malignant tumors growing in endometrium, is one of three major malignant tumors and has a raising incidence in recent years around the world. Adenocarcinoma, resulting from endometrial glands, is the most common and representative endometrial carcinoma. IGFBPs(Insulin-like growth factor binding protein system) is the important member of IGFs(Insulin like growth factor system), however, Insulin like growth factor binding protein-related protein1 has been widely concerned due to its strong ability of combining with insulin. The previous studies of the research group show that IGFBP-r P1 related to insulin resistance is involved in the development of endometrial adenocarcinoma,but the expression and regulation mechanism is unknown.DNA methylation is a hotspot of studying the regulated gene expression now, the studies in colon cancer,gastric cancer, breast cancer and cardia cancer show that the abnormal methylation of IGFBP- r P1 gene is related to gene expression regulation. This study applies methylation specific polymerase chain reaction to detect IGFBP- r P1 gene methylation status of Cp G island, quantitative real time polymerase chain reaction and immunohistochemical SP method respectively to detect the m RNA and protein expression of IGFBP- r P1 gene, aiming at exploring the relationship of IGFBP- r P1 gene methylation status and its m RNA and protein expression, further clarifying the molecular biology mechanism of endometrial adenocarcinoma occurs. Methods1.Experimental tissue samples are divided into three groups: endometrial adenocarcinoma group(45cases), endometrial atypical hyperplasia group(30cases) and endometrial simple hyperplasia group(30cases).2.Methylation specific polymerase chain reaction :to detect the IGFBP- r P1 gene methylation status of Cp G island in the promoter region and the first exon region in every group.3.Quantitative real time polymerase chain reaction :to detect the m RNA expression of IGFBP- r P1 gene in each group.4.Immunohistochemical SP method :to detect the protein expression of IGFBP- r P1 gene in each group.5.Statistical methods:Using SPSS 17.0 software for the statistic analysis of data, chi-square test for the pairwise comparisons in groups of qualitative data, Bonferroni method for correcting the test level. Quantitative data results is expected to be shown by Sx ±, then the results will be represented with analysis of variance after throughing the the test of normality and homogeneity of variance. In addition, LSD-test is used for pairwise comparisons,and the correlation of two variables uses Spearman correlation analysis in this study. Results1.The methylation rate of IGFBP-r P1 gene in the promoter region(15/45) of endometrial adenocarcinoma tissues is higher than in the first exon region(5/45).(χ2=6.429,P<0.05)2.The methylation rate of IGFBP-r P1 gene in the promoter region of endometrial adenocarcinoma tissues is significantly lower than the rate in endometrial atypical hyperplasia(χ2=8.036,P<0.05) and Simple endometrial hyperplasias tissues(χ2=9.696,P<0.05).3.The m RNA and protein expression of IGFBP-r P1 gene in endometrial adenocarcinoma tissues is higher than that in endometrial atypical hyperplasia and simple endometrial hyperplasias tissues(P<0.05),and negative correlation with the degree of methytion.(r=-0.287,P<0.05). Conclusion1.The methylation status of IGFBP-r P1 gene mainly exist in the promoter region of endometrial adenocarcinoma tissue, and it often exists in a low methylation status.2.IGFBP- r P1 gene is highly expressed in endometrial adenocarcinoma tissue, and it has a negative correlation with its degree of methylation status, it prompts the low methylation status in the promoter region of IGFBP-r P1 is a regulatory mechanism of the high expression in endometrial adenocarcinoma.