Cripto-1 (CR-1),
amphiregulin (AR), and
heregulin alpha (HRGalpha) are three recently discovered
epidermal growth factor (
EGF)-related
peptides. 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 cancer cell lines using
reverse transcriptase-polymerase chain reaction (RT-PCR), Northern blotting, and immunocytochemistry (ICC). The expression of CR-1
mRNA was detected by RT-PCR in all of the
breast cancer cell 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 able 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 monospecific rabbit polyclonal
antibodies. The anti-CR-1 antibody was also used to examine 26 human primary
breast carcinomas by ICC for CR-1 expression. Seventy-five percent of the
carcinomas were found to express the CR-1
protein while the adjacent non-involved breast epithelium was negative. These data demonstrate that CR-1, AR, and HRGalpha are coexpressed in human
breast cancer cells and suggest that these three
EGF-related
peptides might perform a role in the autocrine growth regulation of human
breast carcinoma cells.