The Study Of P57^kip2 Gene Promoter Methylation, Genetic Instability, MRNA And Protein Expression In Human Hepatocellular Carcinoma

Objective:In order to research the relation between abnormal expression of p57^kip2 gene and incidence of HCC,this article examine the expression of p57^kip2 from level of mRNA & protein,and the loss of hererozygosity(LOH),microsatellite instability(MSI) and methylation from level of DNA in HCC.Methods:The expression state of mRNA and protein of p57^kip2 gene were detected in situ hybridization and Immunohistochemistry staining,and the LOH and MSI of two microsatellite loci(D11S2351 and D11S569) located on chromosome 11p15.5 region were detected using PCR-polyacrylamide gel electrophoresis technology.p57^kip2 promoter region CpG island methylation were also analysised by methylation-specific PCR (methylation-specific PCR,MSP).Further,we analysis the relationship among expression of p57^kip2 mRNA and protein,LOH,MSI and methylation.Results:1.Expression of p57^kip2 mRNA:There were no expression in normal liver tissue.Expressions both in pericancerous cirrhosis and hepatocellular carcinoma were 26.67%(8/30).The rate of expression of p57^kip2mRNA at different levels in HCC were 0%in high differentiated HCC group, 20.8%in well-differentiated groups,60%in poorly differentiated groups.There were statistically significant in the expression of p57^kip2mRNA between the groups of normal liver and the pericancerous cirrhosis,the normal liver and HCC.But there were not statistically significant between the groups of pericancerous cirrhosis and HCC. The expression of p57^kip2 mRNA have statistical significance in three differentiated groups.2.Expression of p57^kip2 protein:There were no expressions in normal liver tissue.Expressions in precancerous cirrhosis and hepatocellular carcinoma were 56.67%(17/30).The rate of expression of p57^kip2 protein at different levels in HCC were 0%in high differentiated HCC group,54.1%in well-differentiated groups,80%in poorly differentiated groups.There were statistically significant in the expression of p57^kip2 protein between the groups of normal liver and the pericancerous cirrhosis,the normal liver and HCC.But there were not statistically significant between the groups of pericancerous cirrhosis and HCC. The expression of p57^kip2 protein have statistical significance in three differentiated groups.3.LOH and MSI detected:Only 1 case of LOH were identified in 30 cases on one microsatellite locies(D11S569),and 4 case of MSI were showed in both 2 microsatellite locies.There was correlation between the MSI of D11S2351 locies and the expression of p57^kip2mRNA and protein.4.MSP detected:There were 6 HCC of hypermethylation in 30 cases,but there were not correlation between hypermethylation and the expression of p57^kip2mRNA and protein.Conclusions:1.The disorder expressions of p57^kip2mRNA and protein indicated that p57^kip2 may not be as a tumor suppressor gene in hepatocarcinogenesis and prognosis.2.The two microsatellite loci where the p57^kip2 gene is located in were not the frequent loci for LOH and MSI. 3.LOH and MSI may not be one of the reasons that lead to the loss of p57^kip2mRNA and protein in hepatocarcingenesis and prognosis.4.The hypermethylation of p57^kip2 might not lead to the abnormal expression of p57^kip2 mRNA and protein.