Mutation, DNA strand cleavage and nitric oxide formation caused by N-nitrosoproline with sunlight: A possible mechanism of UVA carcinogenicity

Sakae Arimoto-Kobayashi, Yoshiko Ando, Yumi Horai, Keinosuke Okamoto, Hikoya Hayatsu, Jillian E. Lowe, Michael H.L. Green

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

N-Nitrosoproline (NPRO) is endogenously formed from proline and nitrite. NPRO has been reported to be nonmutagenic and noncarcinogenic. In this study, we have detected the direct mutagenicity of NPRO plus natural sunlight towards Salmonella typhimurium. Furthermore, formation of 8-oxo-7,8-di4ydro-2′-deoxyguanosine (8-oxodG), a mutagenic lesion, was observed in calf thymus DNA treated with NPRO plus simulated sunlight. The treatment with NPRO and sunlight induced single strand breaks in the superhelical replicative form of phage M13mp2 DNA. Single-strand DNA breaks also occurred in the human fibroblast cells on treatment with NPRO plus UVA, as detected by the comet assay. An analysis using scavengers suggested that both reactive oxygen species and NO radical mediate the strand breaks. The formation of nitric oxide was observed in NPRO solution irradiated with UVA. We analyzed the photodynamic spectrum of mutation induction and DNA breakage using monochromatic radiation at a series of wavelengths between 300 and 400 nm. Both mutation frequencies and DNA breakage were highest at the absorption maximum of NPRO, 340 nm. The comutagenic and co-toxic actions of NPRO and sunlight merit attention as possible mechanisms increasing the carcinogenic risk from UVA irradiation.

Original languageEnglish
Pages (from-to)1537-1540
Number of pages4
JournalCarcinogenesis
Volume23
Issue number9
DOIs
Publication statusPublished - Sep 2002

ASJC Scopus subject areas

  • Cancer Research

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