Murine sarcoma growth factors affect the growth and morphology of cultured mouse epithelial cells

A mouse embryo epithelial cell line, MMC-E, was used to study the effects of purified murine sarcoma growth factors (SGFs) on the growth of epithelial cells. Murine SGF was a partially purified preparation from the serum-free culture media of mouse fibroblasts transformed by Moloney murine sarcoma virus. SGFs stimulated DNA-synthesis in resting cells and induced them to grow to higher densities than control cells. With continued exposure to SGFs, MMC-E cells lost their postconfluency inhibition of division and formed small expanding foci. When the SGFs were removed and the cells were subcultured, they regained their normal phenotype, showing that the effects of SGFs are reversible on these epithelial cells. SGFs could also stimulate the MMC-E epithelial cells to grow in soft agar, like the syngeneic fibroblasts (MMC-F) from the same mouse embryo, but slower than the control fibroblastic clone. Microgram quantities of SGFs were needed to stimulate soft agar growth of MMC-E cells. The results indicate that SGF can bring about a phenotypic change in the growth pattern of epithelial cells as well as fibroblastic cells.