Expression of stem-cell markers OCT-4 and CD133: Important prognostic factors in papillary renal cell carcinoma

Except for tumor stage and histologic subtype, the prognostic factors of papillary renal cell carcinoma remain controversial. To the best of our knowledge, the prognostic significance of the expression of stem cell markers, OCT-4 and CD133, has not yet been studied in papillary renal cell carcinoma. Expressions of OCT-4 and CD133 were examined immunohistochemically in a tissue microarray construct generated from 119 cases of papillary renal cell carcinoma, collected from November 1996 to December 2008, and then the results were correlated with the clinicopathologic findings. OCT-4 was expressed at the nuclei of tumor cells in 26 cases (22%). The high expression of OCT-4 with a cut-off value of 12.5%, was associated with frequent microscopic lymphovascular invasion and poor disease-specific survival. CD133 was expressed in the apicolateral cell membrane of tumor cells in 21 cases (17.8%) with a cut-off value of 5%. The CD133 expression was correlated with small tumor size and lack of microscopic lymphovascular invasion, and it tended to be associated with a low Fuhrman nuclear grade and prolonged disease-specific survival. On multivariate analysis, tumor stage, histologic subtype, and OCT-4 expression, but not CD133 expression, were independent prognostic factors for disease-specific survival. OCT-4-expressing and CD133-nonexpressing papillary renal cell carcinoma showed the shortest disease-specific survival. These results showed that the expression of stem cell markers, OCT-4 and CD133, may serve, respectively, as a poor and favorable prognostic marker, in papillary renal cell carcinoma.