Cell proliferative activity and expression of cell‐cell adhesion factors (E‐cadherin, α‐, β‐, and γ‐catenin, and p120) in sarcomatoid renal cell carcinoma

BACKGROUND AND OBJECTIVES: Sarcomatoid RCC (renal cell carcinoma) is an uncommon, but not rare, neoplasm which has been shown to have a much worse prognosis than common RCC. The current study was designed to investigate the association of proliferative activity and cell-cell adhesion molecules with sarcomatoid RCC. METHODS: Proliferative activity (Ki-67 labeling index) and expression of cell-cell adhesion associated molecules (E-cadherin, alpha-, beta-, and gamma-catenin, and p120) were examined using immunohistochemical techniques in 11 cases of sarcomatoid RCC. RESULTS: In six patients with sarcomatous component more than 50%, five were died within 24 month after diagnosis. The expression of these molecules within the carcinomatous and sarcomatous components of sarcomatoid RCC was compared. The mean Ki-67 labeling index in the sarcomatous components (12.6%) is statistically higher than in the carcinomatous components (3.7%) (P < 0.05). The expressions of E-cadherin, and alpha-, beta-, and gamma-catenin were statistically decreased in the sarcomatous components compared to the carcinomatous components. However, no differences were observed regarding p120 immunostaining. CONCLUSIONS: The findings of the current study suggest that the range of the sarcomatous component may be a prognostic factor in RCC, and the malignant behavior of sarcomatoid RCC is due to high cell proliferative activity and decreased expressions of E-cadherin and alpha-, beta-, and gamma-catenin in the sarcomatous component.