Protein Identified that Protects against Lymphomas

c-erbB-2 protein expression was investigated immunohistochemically in frozen thyroid tissue specimens from 42 patients using a polyclonal sheep antibody. c-erbB-2 immunoreactivity was detected in 12 out of 17 papillary carcinomas, while no c-erbB-2 protein immunostaining was seen in cases of follicular adenoma (five cases), follicular carcinoma (five cases) or medullary carcinoma (one case), nor in cases of non-neoplastic tissue, including normal thyroid tissue from tumour-bearing glands. RNA was extracted from 51 thyroid tissue samples from 34 of the above patients, and c-erbB-2 mRNA was analysed by slot-blot hybridisation. c-erbB-2 mRNA was detectable in all samples, but papillary carcinomas and lymph node metastases showed significantly higher levels of c-erbB-2 mRNA compared to non-neoplastic tissue. The present demonstration of positive c-erbB-2 immunostaining in papillary thyroid carcinomas is contradictory to previous findings on formalin-fixed, paraffin-embedded material, and emphasises the importance of tissue quality for c-erbB-2 protein detection. During recent years much has been done to elucidate the role of growth factors and oncogenes in the growth and function of normal thyroid follicular cells and in the development and maintenance of thyroid tumours. The c-erbB-2 oncogene encodes a 185 kilodalton trans-membrane glycoprotein with tyrosine kinase activity (Cous-sens et al., 1985; Akiyama et al., 1986). This protein is closely related to, but yet distinct from the EGF-receptor, encoded for by the c-erbB proto-oncogene (Schechter et al., 1985). Recently, a ligand has been proposed for the putative c-erbB-2 growth factor receptor (Lupu et al., 1990). The c-erbB-2 oncogene has been found to be amplified and/or over-expressed at mRNA or protein level in a number of human adenocarcinomas, those of the breast being most extensively c-erbB-2 protein overexpression is currently being evaluated as a potential risk factor in breast cancer patients An analysis of c-erbB-2 and c-erbB mRNA expression in thyroid tumours by RNA slot blot hybridisation demonstrated two-to threefold higher levels of c-erbB-2 and c-erbB RNA in three out of five papillary carcinomas and three papillary lymph node metastases, as compared to non-tumour tissue (Aasland et al., 1988). The higher levels of expression of c-erbB and c-erbB-2 mRNA in the papillary carcinomas were much lower than the levels associated with gene amplification. Southern blot analysis showed no amplification or rearrangements of the c-erbB-2 gene (Aas-land et al., 1988). The results were pursued in a comprehensive analysis of the c-erbB and c-erbB-2 proto-oncogenes in human thyroid neoplasia, using Southern blot hybridisation to detect gene amplification or rearrangement, …