Differentially regulated production of platelet-derived growth factor and of transforming growth factor beta by a human teratocarcinoma cell line

The human teratocarcinoma stem cell line Tera-2 clone 13 is induced by retinoic acid to differentiate in vitro into endodermal or neuroectodermal cell types. In the absence of externally added growth factors, Tera-2 clone 13 cells proliferated at the same rate as in the presence of serum growth factors. Analysis of serum-free medium conditioned by Tera-2 clone 13 cells showed the presence of a polypeptide immunologically and biochemically related to platelet-derived growth factor (PDGF). In addition transforming growth factor beta (TGF-beta), but no TGF-alpha production could be detected. Tera-2 clone 13 cells specifically expressed high levels of the A-chain mRNA, but not the B-chain mRNA of PDGF. During retinoic acid induced differentiation the level of A-chain mRNA became markedly reduced. In contrast the TGF-beta mRNA levels increased significantly upon differentiation. The implications of these findings are discussed in terms of regulation of growth and differentiation in early embryos as well as in (human) teratocarcinomas.