[Comparison and analysis of expression of c-myc and p16 in cervical carcinoma].

BACKGROUND & OBJECTIVE: Activation of proto-oncogene and inactivation of tumor suppressor genes is related to the carcinogenesis of many tumors. It is still unclear whether abnormal expression of c-myc and p16 cooperate in the occurrence and progression of cervical carcinoma, and whether there exists a connection between the expression of two genes and the chemotherapy response of cervical carcinoma. This study was designed to investigate the correlation between the expression of c-myc and p16 and their roles in the genesis and development of the uterine cervical carcinoma and chemotherapy response. METHODS: Using in situ hybridization, 37 cases of cervical carcinoma (including 11 cases after chemotherapy), 21 cases of precancerous lesion and 5 cases of normal cervix were observed for c-myc and p16 mRNA with dig-labeled probes. An image analytic system was used to detect the gray degree values of the positive signals. RESULTS: The positive expression rates of p16 in normal cervix,CIN (cervical intraepithelial neoplasia) and cervical carcinoma were 100%, 71.4%, and 21.6%, respectively (P=0.0001), whereas the expression rates of c-myc were 0%, 42.9%, and 75.7% (P=0.0011), respectively. Statistically significant difference was found among the three groups for both p16 and c-myc. The expression of positive signals of c-myc increased with the increase of malignant degree, and the positive signals in CIN III were also higher than that in CIN II and CIN I. The expression rates of c-myc were decreased in cervical carcinoma after chemotherapy. There was a tendency of negative correlation between the expression of c-myc and p16(r(s)=-0.907). Expression of p16 and c-myc showed no significant difference between effectual and ineffectual chemotherapy groups. CONCLUSION: Both over expression of c-myc and descended expression of p16 may play an important role in the genesis and development of uterine cervical carcinoma. The increased expression of c-myc in different grade CIN suggests that carcinogenesis of cervix be progressive.