Study On The Role Of Aberrant Cell Cycle Regulation In The Pathogenesis Of HPV-associated Cervical Cancer

Objective:To investigate the role of p53 protein inactivation and aberrant regulation of cell cycle in the mechanism of HPV-related cervical cancer. Studay on the role of inactivation of p53Arg protein and p53Pro protein and aberrant regulation of cell cycle in the mechanism of HPV-related cervical cancer.Methods: (1)PCR were performed to detect the HPV16 DNA in cervical cancer. PCR-RFLP was used to detect the distribution of p53Arg72Pro polymorphism. (2) Immunohistochemistry for the expression of p53 protein in HPV positive cervical cancer; (3) The expression of CyclinD1,Cdk4, phosphorylation of Rb and Ki-67(PI) were detected by immunohistochemistry in cervical cancer of p53 weakly positive and negative group; (4) Correlation analysis were performed to analize the relationship between CyclinD1 and Cdk4 expression, with the same as CyclinD1 and phosphorylation of Rb. (5)Comparing the differences in the expression of CyclinD1, Cdk4, phosphorylation of Rb and Ki-67 in cervical cancer of p53 three genotypes. (6) RT-PCR was performed to identify the mRNA expression of Cyclin D1 and Cdk4 in cell lines of p53 three genotypes.Results: (1)The positive rate of HPV16 DNA in cervical cancer group was 70.5%, and significantly higher than the control group (p<0.05); (2) In 100 cases of HPV-positive cervical cancer, the strong positive rate of p53 protein was 31.0% and weakly positive and negative rate was 69.0%; (3)The expression of Cyclin- D1, Cdk4, high phosphorylation rate of Rb and PI values in cervical cancer of p53 weakly positive and ne- gative group were higher than the control group, and there were significant differences (P<0.05); (4)The ex-pression of CyclinD1 and Cdk4 showed a correlation, and so to phosphorylation of Rb and CyclinD1. The PI values in phosphorylation Rb positive group was higher than the negative group (P<0.05). (5)In the p53 weakly positive and negative group of cervical cancer, the distribution of p53 three genotypes were 40.57%(p53Arg), 23.18%(p53Pro), 36.24%(p53Arg/Pro) respectively. The expression of CyclinD1, Cdk4 and the content of Rb Phosphorylation protein in p53Arg genotype and p53Pro genotype in cervical cancer have no significant differences (P>0.05); (6) the relative expression of CyclinD1 and Cdk4 mRNA in the p53Arg genotype and p53 Pro genotype cell lines have no significant differences (P>0.05).Conclusion: (1)The p53 protein expression of negative or weak positive in the HPV-positive cervical can cer,suggesting that p53 protein could be degraded or partly degraded by HPVE6 protein. (2)Cervical can- cer cell proliferation activity increased mainly through Cyclin D1/Cdk4 and Rb phosphorylation way, after degradation of p53 protein.(3) the regulation of cell proliferation activity increased in p53Pro group in ad- dition to CyclinD1/Cdk4 and Rb (Ser 795) phosphorylation way, there may be other mechanisms involved in cell cycle control.