ErbB4 is downregulated in renal cell carcinoma--a quantitative RT-PCR and immunohistochemical analysis of the epidermal growth factor receptor family.

In the present study the authors evaluated the expression of the EGFR family members ErbB2-4 in renal cell carcinoma (RCC). Thirty-one RCCs were examined for gene expression of ErbB2-4 mRNA by quantitative real-time RT-PCR. For eight of the patients samples of nonneoplastic kidney cortex were also evaluated. Expression of ErbB4 mRNA was analysed in the eight matched tumour and kidney cortex samples by isoform-specific real-time RT-PCR analysis. ErbB4 protein expression was analysed by immunohistochemistry. In summary the results showed that ErbB2 mRNA was downregulated in conventional (clear cell) RCC; ErbB3 mRNA levels were low and heterogeneous in both tumours and kidney cortex; ErbB4 mRNA and protein were strongly downregulated in conventional and papillary RCC. Thus, ErbB2 and ErbB4 are not likely to be oncogenes in the majority of RCCs; instead, the observed downregulations suggest that these receptors might function as tumour suppressors in RCC.