Expression of transforming growth factor alpha and epidermal growth factor receptor in human bladder cancer

We analysed the expression of epidermal growth factor receptor (EGFr) and transforming growth factor alpha (TGF-alpha) in human bladder tumours. Tumour biopsies were obtained from 54 patients with primary bladder cancer (18 stage T1 and 36 stage T2-4). The protein and mRNA expression of EGFr and TGF-alpha were quantified by ELISA and competitive RT-PCR, respectively. The EGFr protein level was significantly increased in T2-4 tumours (0.44 x 10(-11); 0.0-27.5 x 10(-11) mol/g) compared with T1 tumours (0.0; 0.0-2.0 x 10(-11) mol/g) (median; range; 2p<0.01). The EGFr protein and mRNA level correlated (Spearman r=0.45, 2p<0.005, n=40). Co-expression of TGF-alpha protein and EGFr protein was significantly associated with muscle invasive tumours (T2-4) (chi-squared=7.9, df=3, p<0.05) and the TGF-alpha protein level correlated significantly with EGFr protein expression (Spearman r=0.56, 2p<0.0001, n=54). While tumour stage correlated with survival, no correlation was observed between survival and the expression of EGFr and/or TGF-alpha. In conclusion, human bladder tumours express both EGFr and TGF-alpha. The expression of EGFr and TGF-alpha are closely correlated, and the expression of EGFr and co-expression of EGFr and TGF-alpha correlate with tumour stage.