Co‐expression of the genes encoding transforming growth factor‐α and its receptor in papillary carcinomas of the thyroid

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Abstract
Transforming growth factor-α (TGF-α) is frequently co expressed with its receptor, epidermal growth factor receptor (EGF-R), in several types of carcinoma and sarcoma. It is believed that this results in an autocrine stimulation of tumor growth in these tumors. We have found that TGF-α and EGF-R/c-erbB RNAs were co-expressed at significantly higher levels in papillary thyroid carcinomas and their lymph-node metastases than in non-neoplastic thyroid tissues. We also observed a low level of expression of RNA specific for insulin-like growth factor I in these tumors, which was highest in a lymphnode metastasis. Autocrine stimulation by TGF-α may thus be a common feature of papillary carcinomas of the thyroid. Since EGF is known to induce proliferation and dedifferentiation of normal thyroid cells in culture, TGF-α and its receptor may play an important role in thyroid carcinogenesis.