Study On The Relationship Between Mdm2, P53 And P21 With Infection Of HPV In Cervical Cancers

Objective To understand the infection of HPV16/18, mutation of p53 gene and the expression of p53,p21 and mdm2 protein in cervical intra-epithelial neoplasia III (CIN III ) , cervical carcinomas and normal cervical tissues. To analyse the potential pathogenic role of HPV16/18 infection and p53,p21 and mdm2 gene abnormality in oncogenesis and development of cervical cancers. To explore the relationship among p53,p21 and mdm2 in development of cervical cancer.Methods HPV16/18 DNA was tested in CIN III ,cervical carcinomas and normal cervical tissues by PCR,and the expression of HPV16/18 E6 mRNA in HPV-positive specimens was tested by RT-PCR. p53 gene mutation in exon 5~8 was tested by PCR-SSCP, and the expression of protein and mRNA of p53 ,p21 and mdm2 was examined by RT-PCR and immunohistochemistry.Results (1)The positive rate of HPV16 in CIN III and cervical carcinomas was 59. 65% (34/57),the positivite rate of HPV18 was 14. 04%(8/57). There was significant difference between the two groups(x2 = 25. 48 ,P<0. 001). (2)The positivite rate of HPV16/18 in CIN III .cervical carcinomas and normal cervical tissues was 66. 67% (8/12), 66. 67(30/45) and 20%(4/20)respectively. The positive rate of HPV16/18 in CIN III and cervical carcinomas was much higher than normal cervical tissues respectively (x2 =5. 12,12. 09; P = 0. 024,0. 0005). (3)The positive rate of E6 mRNA in HPV-positive cervical cancer(18/30) was much higher than that of normal cervical tissues(0/4) (P=0. 039). There was not significant difference between CIN HI and normal cervical tissues, and also between CIN III and cervical cancer tissues. (4)p53 mutation was found in only 2 cases of cervical cancers and were in exon 5 and exon 7 respectively. The 2 cases of mutation were both found in HPV-negative cervical cancers. No p53 gene mutation was found in all of CIN III and normal cervical tissues. (5)The expression of p53 mRNA was detected in all of CIN III .cervical carcinomas and normal cervical tissues. The expression level of p53 mRNA in CIN III and cervical carcinomas was much higher than that of normal cervical tissues(t = 6. 263, P< 0. 001).(6)The expression of p21 mRNA was detected in all of CIN III, cervical carcinomas and normal cervical tissues. The expression level of p21 mRNA in CIN IE and cervical carcinomas was much lower than that of normal cervical tissues(t = 4. 736,P<0. 001). Therewas significant correlation between differentiation , metastasis of lymphoid and expression level of p21 mRNA(P = 0. 004,0. 008). (7)The positive rate of p53,p21 and mdm2 protein in CIN III was 25%,75%and 41. 67% respectively, and 42. 22%, 42. 22% and 55. 55% in cervical cancer tissues,respectively. The positive rate of p53 and mdm2 in CINIII and cervical carcinomas was significant higher than that of normal cervical tissues(P<0. 005). The positive rate of p21 in CINIII and cervical cancer tissues was much lower than that of normal cervical tissues(x2 = 16. 32 ,P<0. 0001). (8)There were 17 co-expression of mdm2 and p53 protein in 22 cases of p53-positive CIN ]H and cervical carcinomas. There was significant correlation between mdm2 protein expression and p53 protein expression(x2 =9. 988, P = 0. 016),but there was no significant correlatinon between p21 and p53 protein expression(x2 =0. 011, P = 0.916).Conclusion (1)The infection of HPV16/18, especially the expressin of E6 gene is closely related to oncogenesis of cervical cancer.(2)p53 protein expression and overexpres-sion are common in cervical cancer,but p53 protein abnormal accumulation might not result from p53 gene mutation. (3)The positive rate of p53 and mdm2 protein in CIN III and cervical cancer tissues was much higher than that of normal cervical tissues, and the positive rate of p21 protein in CIN III and cervical cancer tissues was much lower than that of normal cervical tissues. It suggested that abnormal expression of p21,p53 and mdm2 was related to the oncogenesis of cervical cancer. (4)The abnormality of p53 protein was related to stage of cervical cancer,and the abnormality of p21 protein...