Modulation of a high molecular weight form of transforming growth factor-alpha in human colon carcinoma cell lines

The secretion of transforming growth factor-alpha (TGF-alpha) by several human colon carcinoma cell lines in tissue culture medium was examined. All of the cell lines tested secreted TGF-alpha to varying degrees. Bio-Gel P-30 chromatography of the conditioned media from three of these cell lines (HCT 116, MOSER, FET) indicated differences in the molecular weights of secreted TGF-alpha. In the HCT 116 cell line, the majority of the TGF-like activity had a molecular weight of less than 10,000. For both MOSER and FET cell lines, 20-30% of the TGF-like activity had a molecular weight greater than 15,000. When HCT 116 and MOSER cells were treated with differentiation inducing agents there was an increase in a TGF-alpha species whose molecular weight was greater than 20,000. This indicates a possible alteration in either the processing of the TGF-alpha precursor and/or secretion of precursor products by the different cell lines.