Cellular Characterization and Retroviral Transduction of Short-Term Breast Cancer Cells

The effort to develop cell lines from surgical specimens has been a difficult goal for years. We derived short-term primary human mammary carcinoma cell lines from breast tumors in 20 of 23 patients. Morphologically, cultured cells showed small cells with high nuclear cytoplasmic ratio and larger cells with abundant dense cytoplasm. The nuclei were round to oval with one to four nucleoli. Immunocytochemically, the cells stained positive for keratin. Tumor cells showed phenotypic overexpression of the breast tumor-associated antigen DF3 compared with normal mammary epithelial cells. The doubling time of tumor cells in vitro ranged from 2.6 to 3.6 days. The cultured cells were characterized as mammary carcinoma cells by their tumorigenicity in nude mice. Of 14 of the 23 short-term cell lines tested, 5 grew in nude mice and eventually regressed, 3 grew progressively in nude mice, and the remaining 6 did not grow within 3 months. To examine the feasibility of cytokine gene transfer into human mammary carcinoma cells, we introduced the cDNA for human tumor necrosis factor-α (TNF-α) into short-term cell lines with a ret-roviral vector. In our short-term primary breast cancer cell lines derived from breast tumors, TNF-α secretion ranged between 89 ng/10⁶cells/48 h and 479 ng/10⁶cells/24 h. These findings indicate that short-term primary human mammary carcinoma cell lines can be grown consistently from breast tumors, and that retroviral mediated-cytokine gene transfer into short-term human mammary carcinoma cells is feasible and may be of potential use in immunotherapy trials.