SELECTIVE INTERACTIONS BETWEEN MAMMARY EPITHELIAL-CELLS AND FIBROBLASTS IN COCULTURE

Paracrine interactions between breast-cancer cells (MCF7) and stromal fibroblasts were studied in relation to the presence of steroid hormon es, using co-cultures in which the 2 populations were separated by a m icroporous membrane. Densities and DNA-synthesis rates of the co-exist ing populations were interrelated. Proliferation was, therefore, viewe d as the cumulative result of several factors, some of which are non-s pecific e.g., are density-dependent, and some are specifically related to the feeders' origin and/or to culture conditions. Specific effects were measured and evaluated by stepwise analysis of co-variance. MCF7 stimulated proliferation of fibroblasts differentially. Malignant-tum our fibroblasts were stimulated more than non-pathological ones. The m agnitude of these effects was dependent on the presence of steroids. A similar analytical method was used for evaluating differential stroma l influences on 4 epithelial phenotypic characters commonly used as pr ognostic markers. The estrogen-receptor, progesterone-receptor, pS2 an d catepsine-D phenotypes of MCF7, as well as their interrelations, wer e dependent on the origin of the fibroblasts, i.e., embryonic or adult , normal or tumoral. (C) 1994 Wiley-Liss, Inc.