Expression of Fas and Fas-L in renal cell carcinoma

Abstract

The previous investigations revealed that Fas-L expression on tumor cells can be one of the reasons of tumor growth, or tumor regression, with or without activation of the immune response. The objective of our study was to investigate the expression of Fas and Fas-L in situ in normal human renal tissue as well as in different types of renal cell carcinoma (RCC) according to tumor grading. Expression of Fas and Fas-L was examined in 25 RCCs classified according to nuclear grades: G1-G3 and to cell type: 17 clear cells, 3 chromophilics (2 eosinophilics, 1 basophilic), 2 chromophobes and 3 spindle cells. Ten normal human kidneys were analyzed, too. Indirect immunoperoxidase technique was applied. Spread and intensity of staining of Fas and Fas-L molecules expression were scored semiquantitatively. Distribution of Fas expression in these RCC was typically diffuse. However, Fas-L was almost completely absent in clear cell RCC. In 3 clear cell RCC, some tumor stromal cells exhibited strong expression of Fas-L. On the contrary, chromophilic, chromophobe and spindle cell RCCs grading from G2-G3, manifested variable combinations of Fas and Fas-L expression. The most of clear cell type low grade RCCs manifested intensive and extensive expression of Fas and completely absence of Fas-L. However, RCCs of high grade malignancy belonging to the clear cell, eosinophilic, chromophobe or spindle cell types can have various combinations of Fas and Fas-L expression. It may probably lead to development of different mechanisms of avoidance of immune response to RCC.