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Bifunctional activity of transforming growth factor type β on the growth of NRK‐49F cells, normal and transformed by kirsten murine sarcoma virus
Author(s) -
Jullien Pierre,
Berg Tone M.,
de Lannoy Colette,
Lawrence David A.
Publication year - 1988
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041360123
Subject(s) - transforming growth factor , growth factor , cell growth , biology , epidermal growth factor , cell culture , immunology , microbiology and biotechnology , medicine , biochemistry , genetics , receptor
Abstract Transformation of rat NRK‐49F cells (49F) by Kirsten murine sarcoma virus (Ki‐MSV) renders these cells (Ki‐49F cells) capable of autonomous anchorage independent (Al) growth. As compared to nontransformed 49F cells, the transformation by Ki‐MSV does not modify the cell response to transforming growth factor‐β (TGF‐β) in monolayer conditions, but alters it in A I growth conditions. The growth of nontransformed or Ki‐MSV‐transformed adherent 49F cells is slowed down by porcine TGF‐β, and this effect is reversed by epidermal growth factor (EGF). This decrease in the cell growth rate, induced by TGF‐β, does not affect the cloning efficiency of untransformed and transformed adherent 49F cells. Contrarily, porcine TGF‐β decreases the A I cloning efficiency of Ki‐49F cells in agar‐gelled medium; this effect is only partly reversed by EGF, which does not synergise with TGF‐β to enhance the A I growth as in the case of untransformed 49F cells. Media conditioned by 49F cells, Ki‐49F cells, and chicken embryo fibroblasts contain a latent TGF‐β whose capacity to promote the A I growth of 49F cells and to inhibit that of Ki‐49F cells is unmasked by acidification. The same situation exists concerning TGF‐β from human platelets. Neutral extracts are inefficient in both tests of promotion and inhibition of A I growth and contain an acid‐activable component with an apparent molecular weight of 600 kd. In acid extracts, a 5–9 kd apparent molecular weight component is responsible for the A I growth enhancement of 49F cells and the A I growth inhibition of Ki‐49F cells. Further purification by reverse phase chromatography shows that both activities strictly coelute at the same point (32%) of an acetonitrile gradient. These results indicate that TGF‐β is present in physiological conditions as a latent form which requires activation for inhibiting the A I growth of transformed cells as well as for enhancing that of 49F cells.