A Study About The Suppression Of RASSF1A Expression By Aberrant Promoter Methylation Affecting The Occurance And Progression Of Renal Cell Carcinoma

Part1The expression of RASSF1A protein in renal cell carcinoma and its relationship with clinical features as well as prognosisObjective To investigate the expression of RASSF1A protein in renal cell carcinoma as a basis of further investigation about the DNA methylation of RASSF1A promoter.Methods Using tissue microarray and immunohistochemistry381patients with primary renal cell carcinoma were analyzed in combination of clinical features. Survival analysis was carried out considering a follow-up period of5years.Results Expression of RASSF1A protein was found to be significantly decreased in tumoral cells compared with normal tubular epithelial cells. RASSF1A immunonegativity was significantly associated with tumor size, group stage and histological grade of tumors and showed a tendency for impaired survival in Kaplan-Meier analysis.Conclusion Primary renal cell carcinoma in China demonstrates a loss of RASSF1A expression.Part2The basic characteristics of RASSF1A promoter methylation in renal cell carcinomaObjective To explore the methylation status of RASSF1A promoter and its clinical significance in renal cell carcinoma.Methods Methylation specific PCR was used to examine the methylation status of RASSF1A promoter in renal cell carcinoma. The specimen included100cases of primary renal cell carcinoma and paired adjacent normal tissues.Results RASSF1A promoter showed aberrant methylation in tumors while compared with paired adjacent normal tissues. Remarkable correlation between the RASSF1A promoter methylation status and clinical pathological parameters was detected.Conclusion Down-regulation of RASSF1A expression was probably due to the abnormal methylation of RASSF1A gene promoter in renal cell carcinoma. Part3Bisulfite sequence analysis of RASSF1A promoter in primary renal cell carcinomaObjectives To investigate the methylation spectrum of RASSF1A promoter in renal cell carcinoma with various pathological types, different stages and grades.Methods Through bisulfite sequencing PCR we detected the methylation sites as well as methylation levels within the scale upstream to500bp in the RASSF1A promoter.Results Mild methylation of RASSF1A promoter was detected in the para-cancerous tissues in primary renal carcinoma. More methylated CpG sites and higher methylation levels were accompanied with advanced tumor stage and poor differentiation in clear-cell renal cell carcinoma.Conclusion RASSF1A promoter methylation indicates a role in early tumorigenesis and serves as a developing procedure along with the tumor progression.