EXPRESSION OF AMPHIREGULIN, CRIPTO-1, AND HEREGULIN-ALPHA IN HUMAN BREAST-CANCER CELLS

Cripto-1 (CR-1), amphiregulin (AR), and heregulin alpha (HRGalpha) are three recently discovered epidermal growth factor (EGF)-related pepti des. The expression of these proteins was determined in MCF-7, ZR-75-1 , T-47D, SK-BR-3, MDA-MB-231, MDA-MB-468, and Hs-578T human breast can cer cell lines using reverse transcriptase-polymerase chain reaction ( RT-PCR), Northern blotting, and immunocytochemistry (ICC). The express ion of CR-1 mRNA was detected by RT-PCR in all of the breast cancer ce ll lines. AR mRNA was detected by Northern blot analysis in MCF-7, ZR- 75-1, T-47D, MDA-MB-231, and MDA-MB-468 cells while HRGalpha mRNA was expressed in only MDA-MB-231 and Hs-578T cells. All estrogen receptor- positive cell lines were found to express AR mRNA, and estrogen was ab le to induce AR mRNA expression in estrogen-depleted MCF-7 cells. CR-1 and AR proteins could be immunocytochemically detected in the breast cancer cell lines that were expressing CR-1 and AR mRNA using monospec ific rabbit polyclonal antibodies. The anti-CR-1 antibody was also use d to examine 26 human primary breast carcinomas by ICC for CR-1 expres sion. Seventy-five percent of the carcinomas were found to express the CR-1 protein while the adjacent non-involved breast epithelium was ne gative. These data demonstrate that CR-1, AR, and HRGalpha are coexpre ssed in human breast cancer cells and suggest that these three EGF-rel ated peptides might perform a role in the autocrine growth regulation of human breast carcinoma cells.