PDGF-like growth factor induces EGF-potentiated phenotypic transformation of normal rat kidney cells in the absence of TGFβ

Using a growth factor defined assay for anchorage-independent growth (van Zoelen, E.J.J., van Oostwaard, Th.M.J., van der Saag, P.T. and de Laat, S.W. (1985) J. Cell. Physiol. 123, 151–160), we have studied the ability of polypeptide growth factors produced by Neuro-2A neuroblastoma cells to induce anchorage-independent growth of normal rat kidney cells. Neuro-2A cells produce and secrete a PDGF-like growth factor in addition to TGFβ, which can be fully separated from each other by means of reverse-phase HPLC. Using a new, very sensitive technique for detection of TGFβ in growth factor samples based on its additional ability to act as a growth inhibitory factor, it is shown that the PDGF-like growth factor does not contain any detectable TGFβ. Still this neuro-blastoma derived PDGF-like growth factor is able to induce anchorage-independent growth of NRK cells, particularly in the additional presence of EGF. It is concluded that under growth factor defined assay conditions TGFβ is not esserr tial for phenotypic transformation of NRK cells