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

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.

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.

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.

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.