EXPRESSION OF CADHERIN-6 AS A NOVEL DIAGNOSTIC-TOOL TO PREDICT PROGNOSIS OF PATIENTS WITH E-CADHERIN-ABSENT RENAL-CELL CARCINOMA

In many carcinomas, E-cadherin is considered to be a prognostic marker for patient survivals, and its decreased expression is associated wit h metastatic disease. Among renal cell carcinomas (RCCs), however, onl y 20% of tumors express E-cadherin, whereas a much higher percentage e xpress other cadherins, e.g., N-cadherin and cadherin-6 (T, Shimazui e t at, Cancer Res., 56: 3234-3237, 1996), Among these cadherins express ed in RCCs, cadherin-6 has been identified as a major cadherin in the renal proximal tubules and in the tumors themselves. Hence, we have in vestigated the relationship between prognosis and cadherin-6 expressio n in tumor cells in 43 patients with RCC, Expression of cadherin-6, E- cadherin, and alpha-catenin was detected immunohistochemically and eva luated microscopically as normal, heterogeneous, or absent, Normal, he terogeneous, and absent expression of cadherin-6 were observed in 19, 16, and 8 of 43 cases, respectively. Coexpression of E-cadherin and ca dherin-6 was detected in only 10 cases. Among 30 tumors in which E-cad herin expression was absent, 24 expressed cadherin-6, In addition, the expression pattern of alpha-catenin correlated more highly with that of cadherin-6 than it did with E-cadherin (P = 0.0003 versus 0.025), I n survival analyses, aberrant expression of cadherin-6 correlated with poor survivals both among all patients (P = 0.0009) and in those with E-cadherin-absent RCC (P = 0.0008). These results suggest that cadher in-6 is a major cadherin playing an essential role in cell-cell adhesi on in E-cadherin-absent RCC.