1995 Fiscal Year Final Research Report Summary
Ras and p53 mutations in renal cell carcinomas induced by ferric nitrilotriacetate.
| Project/Area Number |
06670228
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Experimental pathology
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| Research Institution | Okayama University |
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Principal Investigator |
HAMAZAKI Shuji Okayama University Hospital, Assisutant professor, 医学部・附属病院, 助教授 (50208576)
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| Co-Investigator(Kenkyū-buntansha) |
OKADA Shigeru Okayama University, Medical School, Professor, 医学部, 教授 (20033201)
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| Project Period (FY) |
1994 – 1995
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| Keywords | ras / p53 / rat / carcinogen / renal cell carcinoma / radical |
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| Research Abstract |
Iron chelate of nitrilotriacetate (NTA) is nephrotoxic and induces renal cell carcinomas in experimental animals. We suggested that the carcinogenicity of Fe-NTA might be related to its ability to form oxygen free radicals in renal tubules in the previous papers. It is well known that oxygen free radicals induce various DNA lesions such as 8-hydroxydeoxyguanosine (80HdG). The formation of 80HdG in DNA reportedly induces G to T or G to A transversions in vitro, and G to T mutations in experimental tumors are proposed to be a signature mutation of the oxidative damages. In the present study, renal cell carcinomas induced in male Wistar rats by Fe-NTA were examined for mutations in ras oncogenes and p53 tumor suppressor gene to inveatigated whether observed mutations were consistent with oxidative damages.
Fourteen primary tumors and two metastatic tumors from 11 animals were evaluated. Exon 1 and 2 of the H-, K-, and N-ras genes were amplified by polymerase chain reaction (PCR), and the presence of mutations was examined by direct sequencing. Exon 5 through exon 7 of p53 gene were surveyed for point mutations by PCR-single stranded conformation polymorphism (SSCP) analysis. Direct sequencing of the ras genes showed no mutations in codon 12,13, or 61 among the tumors evaluated. SSCP analysis of p53 gene exon 6 indicated conformational changes in two primary tumors. One tumor had a CCG to CTG transition at codon 199, and the other had a ATC to ATT transition at codon 229 and two nonsense C to T transitions. It is concluded that neither ras nor p53 genes play a significant role in the development of Fe-NTA induced renal cell carcinomas. Due to the low incidence of the mutations, the contribution of the oxidative damages to the mutations could not be evaluated.
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