Standard and innovative methodological approaches to induce a differentiated phenotype in human colon adenocarcinoma HT-29 and CaCo-2 cell lines

Human colon adenocarcinoma HT-29 and Caco2 cell lines are extensively used to gain insight not only into mechanisms underlying cancer development, but also into the main intestinal functions. This statement relies on the possibility to use the two cell lines at different degree of differentiation, thus mimicking the heterogeneity of the intestinal epithelium. On this basis, herein we analyzed well studied and alternative approaches for obtaining a differentiated phenotype for each cell line. Cell differentiation was evaluated by means of cell morphology and biochemical markers. In the case of HT-29 cells, the substitution of the standard culture medium (DMEM) with RPMI 1640, the addition of sodium butyrate and the replacement of glucose with galactose were studied (Gravaghi et al, 2007). In the case of Caco2 cells, the adoption of a new methodology consisting of pre-confluent subcultures for at least 50 passages without altering culture conditions generate a population at various stages of differentiation (Ferraretto et al, 2007). Finally, since the active form of vitamin D3 (VitD3), 1,25-(OH)2D3, is both a differentiation agent and a modulator of the active calcium transport in the intestinal cells, we pretreated undifferentiated and differentiated HT-29 and Caco2 cells with the vitamer. The VitD3 pre treatment in HT-29 cells cultured in DMEM resulted in a slightly more differentiated cells, while in RPMI HT-29 cells does not induce any significant morphological changes. The overall effect of VitD3 in Caco2 cells at early passages is promoting differentiation, while at higher passages the effect of VitD3 on cell differentiation was not so evident. Two fundamental conclusions can be derived: i) it is possible to differentiate human adenocarcinoma cell lines without altering their culture conditions; ii) VitD3 can act either inducing a cell differentiation or altering the differentiated phenotype in dependence of the preexisting cell differentiation degree.