Expression of the HER-1-4 family of receptor tyrosine kinases in neuroendocrine tumours.

The type I receptor tyrosine kinase family comprises four homologous members: Epidermal growth factor receptor (EGFR), HER-2, HER-3 and HER-4. Studies have shown that EGFR and HER-2 play a critical role in oncogenesis. In this study we sought to determine the pattern of expression and the prognostic significance of EGFR, HER-2, HER-3 and HER-4 in a variety of neuroendocrine tumours using immunohistochemistry. HER family receptor expression in 82 paraffin-embedded specimens of neuroendocrine tumours using immunohistochemistry was examined. The pattern and protein expression levels for each receptor were correlated with clinical and pathological parameters. EGFR expression was identified in 86.6% samples, HER-2 was not expressed in any samples, HER-3 was expressed in 8.5% samples and HER-4 was expressed 91.5%. EGFR and HER-4 were co-expressed in 79.3% of cases. HER-3 was correlated with better survival. EGFR was not associated with poor prognosis. This study has demonstrated EGFR, HER-2 and HER-4 expression is not associated with poorer survival. HER-3 expression is correlated with better prognosis. Overexpression of EGFR and HER-4 may offer potential new therapeutic targets.