Transforming growth factor-alpha and human cancer.

Human transforming growth factor-alpha TGF-alpha, a polypeptide growth factor which causes reversible transformation of normal cells, is composed of 50 amino acid residues, has a 30 to 40% amino acid homology to epidermal growth factor (EGF), and binds the EGF receptor. In human cancers, studies are beginning to show that TGF-alpha could serve as a tumor marker and as a marker for the malignant potential of a tumor. Thus far, the types of carcinomas with which abnormal TGF-alpha expression has been associated include liver, gastrointestinal, breast, skin, lung, brain and ovarian cancers. TGF-alpha may play a role in the processes involved with tumor initiation and tumor growth. In cell lines, TGF-alpha has been found to be associated with autocrine and paracrine types of cellular growth initiation and with increased levels of oncogene expression. In summary, the evidence concerning human TGF-alpha are that TGF-alpha could serve as a marker for human cancers and that an understanding of the basic actions of TGF-alpha could help to explain the self-sustaining nature of tumors.