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Ferric nitrilotriacetate induces oxidative damage in renal proximal tubules, a consequence of Fenton-like reaction, that ultimately leads to a high incidence of renal cell carcinoma (RCC) in rats. In order to ®nd common genetic alterations in this oxystress-induced carcinogenesis model, RCCs were produced in F1 hybrid rats between Wistar and Long-Evans strains and genomes were screened for loss of heterozygosity (LOH) with microsatellite polymorphic markers by PCR. Five consecutive markers on chromosome 5 (D5Mgh5, D5Mit9, D5Mgh6, D5Mit11 and D5Mit6) showed LOH in 40% of the RCCs. As possible candidate tumor suppressor genes on chromosome 5, p15 INK4B and p16 INK4A were investigated for genetic alteration and aberrant methylation by Southern blot, PCR/SSCP/ sequencing and methylation-speci®c PCR. Genetic alteration (homozygous or hemizygous deletion with or without point mutation) or aberrant methylation were found in 30.7 and 53.8% of the RCC cases, respectively, which was proportionally associated with the histological nuclear grade and metastatic activity. Our data suggest that inactivation of p15 and p16 genes could be one of the major pathways responsible for oxystress-induced carcinogenesis.

Expression of insulin-like growth factor-2 (IGF-2) has been reported in tissue specimens and cell lines of human colorectal cancers. However, the effects of IGF-2 in colorectal cancer patients are not well known. In this study, IGF-2 staining was performed on tissue samples from 92 patients with colorectal cancer, and the relationship of IGF-2 staining to clinicopathological variables, proliferating cell nuclear antigen (PCNA) staining and patient survival was analyzed. IGF-2 staining was correlated with tumor progression, PCNA staining and patient survival. Our results suggest that IGF-2 plays an important role in tumor progression and that IGF-2 staining is useful as a prognostic factor in colorectal cancer patients.