Expression of c-Myc, TGF-alpha and EGF-receptor in sporadic medullary thyroid carcinoma

In 20 patients with sporadic medullary thyroid carcinoma (MTC), immuno-histochemistry was used to localize the expression of the c-Myc oncoprotein, transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) and these three markers were analysed regarding their relation to histopathological and histochemical variables of the tumours. The detection rates of c-Myc, TGF-alpha and EGFR were 90%, 90% and 95% respectively. Concomitant demonstration of the markers was reflected in significant associations (correlation factor between TGF-alpha and EGFR was 0.93, p < 0.001). The markers were almost invariably located within the cytoplasm, which might suggest their crucial role in growth regulation and cell differentiation; this seems especially true of TGF-alpha and EGFR. The different markers showed no relation to either histopathological or histochemical variables (tumour behaviour, tumour size, tumour cell type). The prominent co-expression of c-Myc, TGF-alpha and EGFR proteins indicates that in MTC these factors might be of importance for tumour cell proliferation via autocrine growth stimulation.