Hormone supplemented media for cloning human breast cancer: Increased colony formation without alteration of chemosensitivity

We tested the ability of hormones and growth factors to enhance the colony formation in soft agarose of breast carcinoma using two human breast carcinoma cell lines, MCF-7 and MDA-MB231, MCF-7 could clone in a basal medium supplemented only by insulin, transferrin, prostaglandin F2 alpha, and fibronectin. Combining oestradiol, dexamethasone, insulin, transferrin, and triiodothyronine with a basal medium supplemented with 5% (v/v) foetal bovine serum (FBS) increased colony forming efficiency (CFE) two-to three-fold over the best obtained in serum supplemented medium without hormones. While optimal CFE was seen in the hormonally supplemented medium plus 5% FBS, clonal anchorage independent growth could also be obtained without serum for both cell lines by substituting 0.5-1% (v/v) bovine serum albumin (BSA) for FBS. Although CFE was enhanced with the addition of hormones, they did not substantially alter the in vitro chemosensitivity patterns of the cell lines to 8 cytotoxic drugs. Hormonally-supplemented medium with 5% FBS increased the CFE of a small number of fresh specimens of human breast cancer compared with medium supplemented with serum alone. The systematic study of requirements for the in vitro growth of human breast cancer may improve drug sensitivity testing by increasing our ability to grow this neoplasm in culture.