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

The expression of c-myc, c-erbB-1 and c-erbB-2 in 24 cases of urothelial carcinoma by Southern and northern blot analysis, and immunohistochemistry was examined. The results were compared with the pathological grade and stage. We found elevated mRNA expressions of c-myc and c-erbB-1 in 19 and 11 of 21 cases, respectively, but there was no apparent amplification or rearrangement of these oncogenes in any of the cases examined. By immunohistochemistry using anti-epidermal growth factor receptor antibody, most of the cases showed positive immunoreactivity on the cancer cell membranes, and cancers of higher pathological grade and stage showed more intense staining. By contrast, amplification of c-erbB-2 was detected in four of 24 cases, all of which were assigned to a high pathological grade (G3). Elevated c-erbB-2 mRNA levels appeared to correlate with the pathological grade of the cancers. Positive immunohistochemical reactions to c-erbB-2 were found in the cancer cell membranes in three of 24 cases, which were accompanied by amplification and elevated mRNA levels of c-erbB-2. In conclusion, expressions of c-myc, c-erbB-1 and c-erbB-2 were all elevated in the majority of urothelial carcinomas, but the amplification was not universal.