A factor present in fetal calf serum enhances oncogene-induced transformation of rodent fibroblasts.
Our previous studies indicated that addition of the tumor promoters 12-O-tetradecanoylphorbol-13-acetate (TPA) or teleocidin to Dulbecco modified Eagle medium supplemented with calf serum enhanced T24-induced focus formation in both the murine C3H 10T1/2 and rat 6 embryo fibroblast cell lines. In the present studies we have found that fetal calf serum (FCS) is more potent than 12-O-tetradecanoylphorbol-13-acetate in enhancing T24-induced focus formation, in terms of the number and size of the foci, in both C3H 10T1/2 and rat 6 cells. Time course studies indicate that FCS can exert this enhancing effect when it is added several days after the transfection with T24 DNA. In rat 6 cells, an 11-fold increase in T24-induced focus formation occurred when the transfected cultures were maintained for only 1 day in 5% FCS, starting 4 days after the transfection. Several known growth factors, including epidermal growth factor, transforming growth factors alpha and beta, insulin, and platelet-derived growth factor, did not enhance T24-induced transformation in these cell systems. Fractionation studies indicate that the factor present in FCS has a molecular weight of about 1,300, is not lipid soluble, and is acid, base, and heat stable. These findings suggest that a factor(s) normally present in serum may enhance the emergence of tumor cells in vivo, by acting in concert with an activated oncogene, during the multistage carcinogenic process.
Hsiao
W L
WL
Cancer Center, Columbia University, New York, New York 10032.
Lopez
C A
CA
Wu
T
T
Weinstein
I B
IB
D000818:Animals; D002471:Cell Transformation, Neoplastic; D003470:Culture Media / Q000032:analysis; D004273:DNA, Neoplasm / Q000235:genetics; D005347:Fibroblasts; D011905:Genes, ras; D006133:Growth Substances / Q000097:blood / Q000494:pharmacology; D051379:Mice; D051381:Rats; D014162:Transfection
D003470:Culture Media; D004273:DNA, Neoplasm; D006133:Growth Substances