c-myc, c-erbB-1 and c-erbB-2 expressions in urothelial carcinoma

Confrontation of immunohistochemistry and fluorescent in situ hybridization for the assessment of HER-2/ neu (c-erbb-2) status in urothelial carcinoma

Specific treatments targeted toward oncogenes expressed in cancer cells are currently under development. Patients with urothelial carcinomas showing HER-2/ neu (human epidermal growth factor receptor 2) overexpression are candidates for such a specific treatment (trastuzumab). However, to be effective, this therapeutic approach requires an extremely reliable evaluation of HER-2/ neu status in tumors. In order to assess the status of expression of this gene and to optimize its assessment, we analyzed a series of 64 primary urothelial carcinomas using immunohistochemistry (IHC) with the CB11 monoclonal antibody coupled with fluorescent in situ hybridization (FISH) in 21 cases. Strong HER-2/ neu overexpression was detected using IHC in 15 of the 64 (23%) cases analyzed, and this rate rose to 33% for patients with metastases. HER-2/ neu overexpression, as revealed using IHC, is strongly associated (95%) with gene amplification assessed using FISH. Patients with urothelial carcinomas overexpressing HER-2/ neu using IHC are potential candidates for targeted chemotherapy.

Expression of c-erbB-2 and cytokeratins 7 and 20 in urothelial carcinoma with gland-like lumina

Urothelial carcinoma with gland-like lumina is an uncommon type of tumor, reported only occasionally in literature. Its diagnosis usually does not offer any difficulties, and its prognosis is determined by the accompanying classic transitional or squamous component. It is important though, not to misdiagnose it as a mixed transitional cell adenocarcinoma. In that respect, features such as the type of epithelium lining, the gland-like structures, as well as the type of luminal mucin have been used to make the diagnosis. Recently, an immunohistochemical panel of antibodies has proven helpful in differentiating primary and metastatic adenocarcinomas of urothelial tract from urothelial carcinoma with gland differentiation. In their series of 16 cases, Tamboli et al included only one case of transitional cell carcinoma with gland differentiation. We present two additional cases of urothelial carcinoma with gland-like lumina in two men, 60 and 79 years old, respectively. Both tumors were grade 2 of Ash-Bergkvist, and the stage was pT(1) in both cases. Immunohistochemical study with cytokeratins 7 and 20, and with c-erbB-2, was performed. Both tumors expressed cytokeratins 7 and 20; c-erbB-2 was only expressed in one, in spite of the same staging. Although some relation has been found in animals between gland-like lumina phenotype and expression of epidermal growth factor (the receptor of which is homologous to c-erbB-2), it seems that this relationship might not be constant in humans.

Deregulation of the cytoplasmic tyrosine kinase cSrc in the absence of a truncating mutation at codon 531 in human bladder carcinoma

The involvement of the cytoplasmic tyrosine kinase cSrc was investigated in human bladder carcinogenesis. Kinase activity was determined in tissue lysates from bladder transitional cell carcinoma (TCC) relative to normal epithelia. Strong kinase activation was observed at all stages of carcinogenesis with a peak at the stage pT1, where tumor cells disrupt the basement membrane and invade the submucosa. In agreement with a role for cSrc in cell invasion, immunocytochemistry analysis showed a strong staining of invading cells. An increase in cSrc protein level were also found in most tumor samples, however, it did not correlate with an increase in activity (r = 0.44) suggesting that cSrc is deregulated in these tumors. Indeed, high Src activity was affinity-purified from a column (IRSVSSDGHE(p)YIYVDP-Affigel 10) that specifically retains active Src. Enzymatic regulation involves the C-terminus, recently found mutated at codon 531 in a subset of advanced human colon cancers. However, no such mutations were detected in TCC, suggesting the existence of other mechanisms for kinase activation.