|Budget Amount *help
¥2,800,000 (Direct Cost : ¥2,800,000)
Fiscal Year 1999 : ¥100,000 (Direct Cost : ¥100,000)
Fiscal Year 1998 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1997 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Background : Nitric oxide (NO) is generated in mammalian tissue by the conversion of L-arginine to L-citrulline. The reaction is catalyzed by nitric oxide synthase (NOS). NO has been suggested to have a biphasic action on tumor with both antitumor and tumor promotor activity, of which role has been still controversial. Recent reports demonstrated that Caveolin-1 and caveolin-3 inhibited eNOS and iNOS activity in vitro. In this study, we investigated the role of iNOS, caveolin-1 and caveolin-3 in progression of renal cell cancer (RCC).
Materials and Methods : Surgical specimens were obtained from 50 patients of RCC.Immunoperoxidase staining was performed using the streptavidin-biotin bridge technique with staining anti-iNOS, caveolin-1, and caveolin-3 monoclonal antibodies. Apoptotic cells were examined by TUNEL method and subset analysis of tumor infiltrating lymphocytes (TIL) was also performed. RNA was extracted from RCC cell lines, ACHN, A498, KRCY, KH39, Cakil and Caki2, iNOS, caveolin-1 and caveolin-3 mRNA expression was examined by RT-PCR method.
Results : Weak iNOS expression was detected by immunohistochemical staining only in 2 cases (0.5%) out of 50 primary tumors and in 1 out of 5 distant metastasis, In contrast, 2 out of 4(50%) of tumor thrombi were highly positive for iNOS.In vitro study, caveolin-1 was generally expressed on all cell lines, however, caveolin-3 expression was significantly reduced in more potent infiltrating phenotype, ACHN and KRC/Y than the others.
Discussion and Conclusion : NO is one of the major angiogenesis factors in human neoplasm. Our data suggest that iNOS expression of tumor thrombus site of RCC may lead to intravascular infiltration and tumor progression. Downregulation of caveolin-3, an inhibitor of iNOS, may also play an important role in RCC progression in vivo.