Immunohistochemical analysis of the expression of ras oncogenes in human renal cell carcinomas.

Fifty-one cases of human renal cell carcinoma were investigated for immunohistochemical localization of ras oncogenes and their products. The immunohistochemical results were evaluated comparatively with the histological grade, stage and progression of the tumor. The ras p21 oncogene product was positive mainly in the plasma membrane of the renal cell carcinomas. The tissues from normal kidneys were limitedly stained in the cytoplasm of the proximal convoluted tubule cells. Five of 28 (17.9%) frozen specimens of renal cell carcinoma revealed the positive staining for ras mRNA by means of in situ hybridization as well as the strongly positive staining for ras p21 gene products. These 5 cases were all grade 2 and pT2b in TNM classification. However, there was no point mutation on exon 1 (corresponding to codons 12 and 13) and exon 2 (corresponding to codon 61), where point mutations are reported in several human tumors. Positive staining cases for ras p21 (survival rate of 81.2% at 5 years) showed the tendency to decrease the survival rate compared to the ras p21 negative staining cases. There was a significant correlation of ras p21 positive staining and the pathological extent of the primary tumor (pT) (p<0.05). Our immunohistochemical study revealed that the expression of ras p21 is one of the parameters related to the prognosis of renal cell carcinomas.