COMPARISON OF INTRACELLULAR AND EXTRACELLULAR TRANSFORMING GROWTH-FACTORS FROM NONTRANSFORMED AND CHEMICALLY TRANSFORMED MOUSE EMBRYO CELLS

Abstract

Multiple transforming growth factors (TGF) were isolated from the serum-free conditioned media and acid-ethanol cell extracts of nontransformed AKR-2B and chemically transformed AKR-MCA mouse cells. The TGF activity was analyzed using Bio-Gel P-60 chromatography in 1 M acetic acid and tested for colony-stimulating activity in soft agar using AKR-2B, AKR-2B (clone 84A), NRK and AKR-McA cells as indicators. Intracellular and extracellular TGF activity from AKR-MCA and AKR-2B cells show a major peak of AKR-2B and epidermal growth factor-potentiated NRK colony-stimulating activity that coelute in the 13,000 .+-. 2000 MW region. In the 24,000 .+-. 7000 MW range, AKR-MCA cells produce intracellular and extracellular NRK colony-stimulating activity that is not potentiated by epidermal growth factor, while the intracelllar and extracellular NRK colony-stimulating activity produced by AKR-2B cells requires added epidermal growth factor for colony formation. Also important in determining the growth and morphological characteristics of a cell line, besides the production of a TGF, is the ability of a cell to respond to TGF activity. The transformed AKR-MCA cells from more colonies than AKR-2B cells in response to certain TGF activities. This suggests that the increased responsiveness of AKR-MCA cells to TGFs may be important in determining its phenotype.