Abstract
We established a novel cancer cell line (MAST) from the ascitic fluid of a metastatic infiltrating ductal carcinoma of the breast. The epithelial and neoplastic nature of the MAST cells was confirmed by ultrastructural analysis. The cell line was maintained as a monolayer with a doubling time of about 68 h, and it possessed an abnormal karyotype with a modal chromosome number of 60, a trisomy of chromosome 18 and other unidentified rearranged chromosomes. Among the markers consistently found in MAST metaphases, we noted a t(14; 14) and a very large subtelocentric, a large satellited acrocentric and a very large submetacentric chromosome with striking fluorescent bands. Immunoenzymatic assay demonstrated that the MAST cell line was positive for estrogen and progesterone receptors. The in vitro drug-sensitivity assay showed a marked resistance of the cell line to 5-fluorouracil and 4-hydroperoxycyclophosphamide and a moderate resistance to etoposide and 4'-epidoxorubicin. The molecular analysis showed a four-to sixfold amplification of the c-myc gene and no amplification or rearrangement of the int-2, c-erbB-2, c-Ha-ras, c-mos and hst-1 genes.