Reversible and irreversible anchorage independent growth in skin cells

We have investigated the regulation of anchorage-independent growth (AIG) by basic fibroblast growth factor (bFGF) and 12-O-tetradecanoyl phorbol-13-acetate (TPA) in JB6 mouse epidermal cells in the context of wound repair versus carcinogenesis responses. bFGF induces an unusually efficient but reversible AIG response, relative to TPA-induced AIG which is irreversible. Distinct global gene expression profiles are associated with anchorage-independent colonies arising from bFGF-stimulated JB6 cells, relative to colonies arising from fully tumorigenic JB6 cells (RT101), including genes exhibiting reciprocal regulation patterns. Thus, while TPA exposure results in commitment to an irreversible and tumorigenic AIG phenotype, the AIG response to bFGF is reversible with essentially complete restoration of normal cell cycle check point control following removal of bFGF from growth medium. These results are consistent with the physiological role of bFGF in promoting wound healing, and suggest that natural mechanisms exist to reverse transformative cellular phenotypes associated with carcinogenesis. Keywords: cell phenotype comparison To determine whether there were shared transcriptional effects between reversible and irreversible AIG, we performed global microarray analyses on colonies isolated from soft agar for both bFGF-treated JB6 cells and fully tumorigenic JB6 cells from the RT101 cell line. Gene expression changes associated with colony formation were determined by comparison to respective monolayer control cells.