Transforming Growth Factor-α Precursors in Human Colon Carcinoma Cells

Among the proteins of the epidermal growth factor family, transforming growth factor-α (TGF-α) may be an especially reliable indicator of metastasis or prognosis in human colorectal carcinomas. Moreover, anomalous forms of TGF-α have been detected in several tissues of cancer origin, suggesting a role of these forms in the development of the disease. This study was designed to identify the presence of TGF-α precursors in different colon cancer cell lines by mean of immunocytochemistry and western blotting techniques. Pro-TGF-α was detected in all cell lines tested. Staining for pro-TGF-α was observed in cytoplasm. Monoclonal antibody to TGF-α detected two bands of 20 and 21 kDa. Polyclonal antibody to pro-TGF-α revealed five bands ranging from 15 to 24 kDa. All these proteins were also detected in nonmalignant cells expressing a transfected rat pro-TGF-α gene. In conclusions, transformation in these human colon carcinoma cells is not due to the presence of anomalous forms of TGF-α precursors.