ENHANCEMENT OF TUMORIGENICITY OF HUMAN BREAST ADENOCARCINOMA CELLS INNUDE-MICE BY MATRIGEL AND FIBROBLASTS

The failure of MCF7 cells to induce the formation of tumours after sub -cutaneous inoculation into athymic nude mice can be obviated by the s imultaneous injection of an extract of basement membrane proteins (mat rigel). Tumour growth is promoted and the latency period is low (2 to 4 weeks). In the absence of matrigel, the simultaneous inoculation of fibroblasts and MCF7 cells also resulted in the development of tumours , but with a longer latency period (about 2 months). The tumorigenic s ynergy between matrigel and fibroblasts was evidenced by co-inoculatin g MCF7 cells MDA-MB 231 cells with fibroblasts and matrigel. This co-i noculation decreased the delay of appearance of the tumours and/or acc elerated the tumour growth, depending upon the number of fibroblasts i njected. Repeated injections of fibroblasts conditioned medium, at the site of inoculum of tumour cells also enhanced tumour growth, suggest ing the involvement of soluble factors secreted by fibroblasts. Histol ogically, tumours induced by co-inoculation Of tumour cells and fibrob lats contained more stromal structures including vimentin-positive cel ls, fibronectin and interstitial collagens. These data suggest that hu man tumours may be reconstituted and grown in athymic nude mice using basement membrane components and fibroblasts as inductors.