QUANTITATIVE DETECTION OF AMPLIFICATION OF PROTOONCOGENES IN BREAST-CANCER

In the present study, dot-blot hybridization, serial dilution analysis and densitometric scanning were used to detect amplification of proto - oncogenes including c-erbB2, c-myc, int-2 and c-Ha-ras in 101 paraff in-embedded breast cancers. Expression of c-erbB2 was also examined by immunohistochemistry. Amplification of c-erbB2, c-myc and int-2 genes was found in 34.7%, 17.8% and 11.9% of breast cancers respectively. H owever amplification of c-Ha-ras was not detected in all cases. In 11. 9% of cases co-amplification of two or more oncogenes was observed. Po sitive immunostaining of c-erbB2 was seen in 23.8% of the cases and it was significantly associated, but not always corresponding to the amp lification of the gene. There was no difference between primary and me tastatic breast cancer in the alterations of proto-oncogenes examined in this study, which suggested that the amplification and overexpressi on of these proto-oncogenes occured prior to and maintained in the pro cess of metastasis of breast cancer. Statistical analysis showed that high-scale of immunopositive staining of c-erbB2 and high-fold eo-ampl ification of proto-oncogenes were significantly correlated with large size of the tumour and the number of involved lymph nodes. Our results indicate that the alterations of multiple oncogenes are involved in t he development of breats cancer and some of them may have prognostic i mportance for breast cancer patients.