Summary The structure and expression of the proto-oncogene c-erbB-2 was studied in 86 patients with transitional cell carcinoma. Initial tissue samples comprised 37 grade 1, 32 grade 2 and 13 grade 3 tumours and four cases of carcinoma in situ. At the time of this first tumour sample, amplification of the c-erbB-2 gene was demonstrated by Southern blotting in 1/37 grade 1, 5/32 grade 2 and 6/13 grade 3 tumours (0.005< P<0.01). Tumour 're-occurrences' were obtained from 23 of these patients on one or more occasions. Amplification was detected in re-occurrences from seven of these 23, none of whom showed amplification in the first tumour sample. DNA was also extracted from exfoliated cells in urine collected from five cases of carcinoma in situ and c-erbB-2 amplification was demonstrated in one of these. No gene amplification was identified in patients' lymphocytes, ten biopsies of normal urothelium and 22 various intravesical pathologies. Increased expression of c-erbB-2 mRNA correlated with amplification of the gene. In addition, raised levels of mRNA were seen in the absence of gene amplification in six tumours. Immunoblotting using the polyclonal antibody 21N, raised against the c-terminus of the c-erbB-2 protein demonstrated increased amounts of a 185 kD immunoreactive protein in tumours with increased c-erbB-2 gene copy number compared with control tissues. In some tumours with high c-erbB-2 gene copy number, a 155 kD immunoreactive protein not detected in controls was expressed at higher level than the 185 kD protein. Immunocytochemistry using a monoclonal antibody AB-3, raised against the c-terminus of the c-erbB-2 protein, showed a positive reaction in the cytoplasm and cell membrane of tumours with gene amplification and in 40% of tumours with no amplification. An association was found between c-erbB-2 amplification and over-expression and the development of tumour re-occurrences. We suggest that c-erbB-2 amplification and over-expression may provide a useful molecular marker in transitional cell carcinoma of the bladder and merits further investigation as a potential prognostic indicator.Transitional cell carcinoma of the bladder is the fourth most common cancer in males in the United Kingdom (HMSO,
The level of expression and cellular localization of the c-erbB-2 gene product in transitional cell carcinoma of the urinary tract is controversial. Analysis of the c-erbB-2 gene structure and comparison of its expression in the same cells by Southern, Northern and immunoblotting, and by immunocytochemistry minimize the errors of interpretation inherent in one technique. Such a 'correlative study' has been performed on tumours from 82 patients. c-erbB-2 gene amplification was detected in 14 per cent of initial tumours and was associated with grade (P < 0.001). Raised levels of mRNA were seen in those tumours with increased gene copy number and in 13 per cent of the remainder. Immunoblotting detected the expected 185 kD immunoreactive protein and a 155 kD protein associated with high gene copy number. Immunocytochemistry localized c-erbB-2 immunoreactivity to the cell membrane and cytoplasm, and the latter predominated. Four antibodies to c-erbB-2 (AB-3, 21N, pAb 1, and NCL CB11) were compared on contiguous sections of the same tumour and showed the same pattern of immunoreactivity. Similarly, analyses carried out in three independent laboratories identified the same cellular localization. Membrane and cytoplasmic immunoreactivity was demonstrated in all tumours with gene amplification or increased mRNA levels and in 40 per cent of the remaining tumours. We showed that immunocytochemistry requires careful standardization of techniques and quantitation between different groups. However, despite variations in the intensity of immunoreactivity, the total number of positive cells remained constant. Therefore quantitation must be based on the number of positive cells and, ideally, their immunoreactive content relative to normal and positive tissue controls.
The growth patterns of established cell lines from bladder transitional cell carcinoma (TCC) were compared with early passage cell lines. The growth of established cell line 5637 was uninhibited in both serum free (basal) and serum containing media. The early passage line (DR) grew only in serum containing medium. This confirms the unreliability of results from biological studies on established (continuous) cell lines.
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