Growth of cells on a perfluorocarbon-medium interphase: a quantitative assay for anchorage-independent cell growth

A high density, purified, nontoxic solvent, heptacosafluorotributylamine (FC43), was successfully used as a culture surface for growing several normal and oncogene-transformed cell lines under anchorage-independent conditions. Normal rat kidney (NRK) fibroblasts and the normal mammary epithelial cell lines NMuMG and A1, clone N4, of murine and human origin, respectively, failed to grow at a FC43 growth medium interphase or in soft agar in the absence of transforming growth factor alpha (TGF alpha) and transforming growth factor beta (TGF beta). However, NRK fibroblasts transformed with the Kirsten ras viral oncogene (K-NRK) or NMuMG cells transformed with a point-mutated c-Harvey-ras proto-oncogene or polyoma middle T-transforming gene (NMuMG-rasH and NMuMG-pyt, respectively) exhibited rapid growth and formed large colonies when cultured on an FC43-medium interphase. In addition, NRK cells treated with TGF alpha and TGF beta and K-NRK cells grown on FC43 exhibited a sensitivity to the growth inhibitory effects of 4-cis-L-hydroxyproline comparable to that observed for the same cells grown in soft agar. These results demonstrated that the two-phase assay system (FC43-growth medium interphase) may be superior to soft agar for monitoring the anchorage-independent growth of cells because of the ease of cell plating, the ability to recover cells and secreted products from the upper aqueous phase, and the shorter growth period required to complete the assay (3-4 days).