Selective interactions between mammary epithelial cells and fibroblasts in co‐culture

Abstract

Paracrine interactions between breast‐cancer cells (MCF7) and stromal fibroblasts were studied in relation to the presence of steroid hormones, using co‐cultures in which the 2 populations were separated by a microporous membrane. Densities and DNA‐synthesis rates of the co‐existing populations were interrelated. Proliferation was, therefore, viewed as the cumulative result of several factors, some of which are non‐specific, 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 covariance. MCF7 stimulated proliferation of fibroblasts differentially. Malignant‐tumour fibroblasts were stimulated more than non‐pathological ones. The magnitude of these effects was dependent on the presence of steroids. A similar analytical method was used for evaluating differential stromal influences on 4 epithelial phenotypic characters commonly used as prognostic markers. The estrogen‐receptor, progesterone‐receptor, pS2 and cathepsine‐D phenotypes of MCF7, as well as their interrelations, were dependent on the origin of the fibroblasts, i.e., embryonic or adult, normal or tumoral.