Transforming growth factor alpha and epidermal growth factor levels in bladder cancer and their relationship to epidermal growth factor receptor

We have examined levels of epidermal growth factor (EGF) and transforming growth factor alpha (TGF-α) in neoplastic and non-neoplastic bladder tissue using a standard radioimmunoassay technique. Tumour samples had much higher TGF-α levels compared with EGF and TGF-α levels in malignant tissue were significantly higher than in benign bladder samples. There was, in addition, a difference in mean EGF levels from 'normal' bladder samples from non-tumour bearing areas of bladder in patients with bladder cancer compared with 'normal' bladder tissue obtained at the time of organ retrieval surgery. Levels of EGF and TGF-α did not correlate with levels of EGF receptor (EGFR) as determined by a radioligand binding method but levels of TGF-α > 10 ng gm^-1 of tumour tissue did correlate with EGFR positivity defined using immunohistochemistry. These data suggest that TGF-α is the likely ligand for EGFR in bladder tumours.