Influence of in vitro culture conditions on tumor cell differentiation

We studied the influence of different in vitro culture conditions on the growth characteristics of certain human and murine tumor cell lines maintained in either conventional medium supplemented with FCS or in serum-free synthetic medium. A lower growth rate was observed for all of the cell lines maintained in serum-free conditions. Three human melanoma cell lines which were Ia-positive and showed an absence of pigmentation in the presence of FCS, without it produced melanin and lost their Ia antigens. In serum-free conditions, a murine hybridoma lost its membrane IgM and two human carcinoma cell lines expressed and secreted an increased amount of several tumor markers identified by monoclonal antibodies. The results of the study are in keeping with the hypothesis that tumor cell lines cultured in serum-free medium acquire differentiation characteristics.