We have established a novel human breast carcinoma cell line, HMA-1, derived from ascites of a female breast cancer patient. HMA-1 was shown to be an epithelial cell line with intracytoplasmic duct-like vacuoles, microvilli, desmosomes and tonofibrils in accordance with human breast cancer. The cell line demonstrated a good cell growth ability in monolayer fashion with a doubling time of 46 hr. Based on a whole cell binding assay the cell line contained estrogen receptor (1.45>< 10-4 sites/cell). Tamoxifen, an anti-estrogen agent induced a dose-dependent decrease in the cell growth rate, but estradiol stimulated the cell growth. HMA-1 could be transplanted subcutaneously into BALB/c nude mice, and was able to cause tumors approximately two months after heteroinoculation. These results indicate that HMA-1 cell line may serve as a new human breast carcinoma cell line which could be utilized in the breast cancer research. breast neoplasm ; human cell line ; estrogen receptor Breast carcinoma remains the leading cause of cancer mortality among women in western countries and its incidence is rising worldwide including Japan. Human breast carcinoma cell lines are needed for multidisciplinary research in breast cancer. There are a few well-characterized cell lines, derived from human breast carcinomas. The first report attempting to culture breast carcinoma cells appeared in 1937 (Cameron and Chambers), but there were no other reports until 1958 when Lasfargues and Ozzello established the first successful long-term culture of human breast carcinoma cells . Since then various kinds of human breast cancer cell lines have been reported (Soule et al. 1973 ;Trempe and Fogh 1973;Cailleau et al. 1974; Breast Cancer Task Force Cell Culture Bank,

This report describes the characterization of an estrogen receptor-positive breast cancer cell line, HMA-1, established from a breast cancer patient, based on the expression of tumor-associated antigens (TAAs), the HLA-DR antigen, and the c-erbB-2 proto-oncogene product. In flow cytometric and immunohistochemical analyses, HMA-1 was found to express increased levels of several TAAs including MUC1, TAG-72 (sialyl Tn), Tn, T, sialyl Le(a), Le(x), and Le(y). HMA-1 also expressed enhanced levels of the HLA-DR antigen and c-erbB-2 protein. These results indicate that HMA-1 is a unique cell line with abundant TAAs which may serve as an appropriate breast cancer cell line for application in the multidisciplinary research of breast cancer.