Fibroblast growth factor induces the soft agar growth of two non-transformed cell lines

Recent studies have determined that fibroblast growth factor (FGF) potentiates the soft agar growth responses of NRK-49F cells to several combinations of transforming growth factors (TGFs). In the current study, two other non-transformed cell lines, NR-6 and AKR-2B, which do not spontaneously form colonies in soft agar, were examined for their soft agar growth responses to FGF. Both the acidic form and basic form of FGF were found to induce the soft agar growth of these cells. In the case of NR-6 cells, the effects of TGF-beta were also examined. TFG-beta potentiated the soft agar growth response of NR-6 cells to FGF, but on its own did not induce soft agar growth. Attempts to identify other factors capable of modulating the response of these cells to FGF, led to the finding that both 12-O-tetra-decanoylphorbol-13-acetate and retinoic acid suppress FGF-induced soft agar growth of NR-6 cells and AKR-2B cells. The finding that FGF induces the soft agar growth of both non-transformed cell lines, together with the findings of others that both forms of FGF are angiogenic, lends further support to the suggestion that FGF plays a significant role in the in vivo growth of some, and possibly many, tumors.