C-ERBB3 EXPRESSION IN BREAST-TUMOR DERIVED CELL-LINES

The c-erbB3 protein is a type 1 growth factor receptor. mRNA for c-erb B3 is expressed in several breast cancer cell lines and c-erbB3 protei n has been detected by immunocytochemical staining in primary breast c ancers. The relationship between protein expression and mRNA expressio n has not, however, been explored in detail. In this report we have us ed immunoprecipitation, Western blotting, immunocytochemistry, ELISA a nd FACS to assess the prevalence and level of c-erbB3 protein expressi on and its concordance with mRNA levels estimated by Northern blotting , in a series of breast cancer cell lines. The protein was found at lo w levels, consistent with the reported lack of the c-erbB3 gene amplif ication, and expression was generally proportional to the level of mRN A.