DIFFERENTIATION OF TERATOCARCINOMA STEM-CELLS IS MARKED BY THE TYPES OF COLLAGEN WHICH ARE SYNTHESIZED

A cloned line of undifferentiated teratocarcinoma cells (OC15S1) was either maintained as a homogeneous embryonal carcinoma (EC) cell population or was cultured under conditions where the cells differentiated into endoderm-like (END) cells. In this study we examine the synthesis of collagen in both EC and END cells. Cell cultures were incubated with tritiated proline and lysine, and the radioactive collagen secreted into the medium was extracted and purified or immunoprecipitated by antibodies to type IV collagen (Adamson and Ayers, 1979). Radioactive collagens were identified by electrophoretic mobility, by sensitivity to collagenase and to reduction, by insensitivity to pepsin, by cyanogen bromide peptides, and by aminoacid analyses of 3-hydroxyproline, 4-hydroxyproline and proline. OC15S1 EC cells were found to synthesize several collagenous polypeptides, of which 60-70% of the radioactivity was like that of basement membrane (type IV) collagen. Type I-like collagen was the main collagenous product of END cells, but a minor product of EC cells. We concluded that type IV collagen synthesis was suppressed during the differentiation of EC cells to END, while type I-like synthesis was increased. Similarly, other EC cell lines produced mainly type IV-like collagen polypeptides (PC13, F9, PSA1), and following the formation of END cells, two lines produced mainly type I-like collagen polypeptides (PC13, C145b). The type of endoderm formed on embryoid bodies, however, presents an alternate route of differentiation, since immunoperoxidase tests showed that it was synthesizing significant amounts of type IV collagen. We discuss the significance of these findings in relation to a similar change which occurs during normal development. © 1979.