CLONAL EXPANSION OF EPITHELIAL-CELLS FROM PRIMARY HUMAN BREAST-CARCINOMA WITH 3T3 FEEDER LAYER TECHNIQUE

3T3 feeder layer technique provided support for clonal growth and seri al propagation of two apparently single epithelial cells isolated from a peroperative biopsy of a primary ductal breast carcinoma The total culture lifetime was estimated to be more than 30 doublings, 21 of whi ch took place during the primary culture. The two cells were the only survivors of two-week exposure to stressing conditions that resembled the microenvironment in a tumour (low pH, depleted nutrition and accum ulation of metabolic waste). The epithelial character of the cells was proved by positive immunostaining for keratins 7/17. The majority of growing cells did not express keratin 19. Only quiescent cells in some colonies, which appeared to reach a more advanced stage of differenti ation, expressed keratin 19. These features correspond with the charac teristics of mammary luminal cells which in vivo undergo differentiati on from the stem K19(-) to secretory K19(+) cells. The luminal cells a re supposed to be the target of malignant transformation in the mammar y gland. The described technique opens a regular way for the in vitro clonal growth of individual primary cells from breast tumours. Such an approach can improve our understanding of the biology of breast cance r cell populations and also simplify the predictive chemosensitivity a ssay on breast cancer cells from individual patients.