This study aimed to analyze expression of S100A10, annexin II and B-FABP genes in renal cell carcinoma (RCC) and their potential value as tumor markers. Furthermore, any correlation between the gene expression and prognostic indicators of RCC was analyzed. Expression of each gene was estimated by RT-PCR in the nonneoplastic (normal) and tumorous parts of resected kidney samples. Also, each antigen was immunostained in RCC and normal kidney tissues. Expression of the S100A10 gene averaged 2.5-fold higher in the tumor than that in the normal tissues (n = 47), after standardization against that of β β β β-actin. However, expression of annexin II, a natural ligand of S100A10, was only 1.64-fold higher. In the tissue sections of RCC, S100A10 and annexin II were immunostained in membranes. In the normal renal epithelia, however, both antigens were stained in the Bowman's capsule and the tubules from Henle's loop through the collecting duct system, but not in the proximal tubules, from where most RCC are derived. In contrast, expression of the B-FABP gene was 20-fold higher in the tumor. No B-FABP was immunohistochemically detected in normal kidney sections, but it was stained in the cytoplasm of RCC tissue sections. S100A10 and B-FABP genes were overexpressed regardless of nuclear grade and stage of RCC. Immunopositivity in RCC tissues (n = 13) was 100% for S100A10 and annexin II, and 70% for B-FABP; however, no clear relationship was observed in either antigen with nuclear grade and stage. It was found that all three performed well as RCC markers. B-FABP was most specific to RCC, as it was expressed little in normal kidney tissues. (Cancer Sci 2007; 98: 77-82) W e have previously described the overexpression of S100A10 in renal cell carcinoma (RCC) cells compared with the normal human kidney cDNA library.(1) Such overexpression has been confirmed in RCC and non-neoplastic (normal) tissues in surgically resected kidneys (n = 7).(1,2) S100A10 is a member of the S100 family of proteins that are small acidic calcium-binding proteins with two helix-loop-helix EF-hand motifs. Twenty human S100 family members are expressed in a cell-and tissue-specific manner, and are responsible for a variety of cellular processes including cell proliferation and differentiation.(3,4) Sixteen of their genes (designated S100A1-S100A16) are clustered on the chromosome 1q21 region, where a number of chromosomal abnormalities occur with neoplasias.(4) S100A10 forms a heterotetramer with annexin II (S100A10) 2 (annexin II) 2 , and the complex localizes in the extracellular membrane of various cancer cells. In the present study, we estimated the gene expression of S100A10 and annexin II by reverse transcription-polymerase chain reaction (RT-PCR) in a larger number of surgically resected RCC samples (n = 47) after standardization for the expression of β-actin in each sample. Then we immunohistochemically investigated the expression of S100A10 and annexin II in RCC and normal kidney tissues (n = 13). The extracellular S100A10/ annexin II complex f...

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