Comparative analysis of cellular and extracellular proteins secreted by two human tumor cell lines

Two human tumor cell lines, melanoma (TWI) and colon carcinoma (HT-29), replicate continuously in serum-free C-ITS medium [Chee's essential medium (CEM) supplemented with insulin (5 ng/ml), transferrin (5 micrograms/ml), and (5 ng/ml)]. The TWI cells assume normal morphology during growth, whereas the HT-29 cells become rounded and tend to aggregate in C-ITS medium. Under these conditions the two cell types synthesize a number of different cellular proteins, and TWI releases a number of proteins to the medium. These proteins include some factors which are needed for spreading and adhesion of the cells to the growth substrate as shown by the growth of HT-29 cells in serum-free C-ITS medium conditioned by TWI cells. HT-29 cells do not synthesize such factors or perhaps, do so in negligible amounts. The serum-free medium conditioned by the TWI cells may provide an approach for the cultivation of various human tumor cells in vitro.