Oxidative DNA damage induced by hair dye components ortho-phenylenediamines and the enhancement by superoxide dismutase

Abstract: There is an association between occupational exposure to hair dyes and incidence of cancers. Permanent oxidant hair dyes are consisted of many chemical components including ortho-phenylenediamines. To clarify the mechanism of carcinogenesis by hair dyes, we examined DNA damage induced by mutagenic ortho-phenylenediamine (o-PD) and its derivatives, 4-chloro-ortho-phenylenediamine (Cl-PD) and 4-nitro-ortho-phenylenediamine (NO2-PD), using 32P-labeled DNA fragments obtained from the human p16 and the p53 tumor suppressor gene. We also measured the content of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), a marker of oxidative DNA damage, in calf thymus DNA with an electrochemical detector coupled to a high performance liquid chromatograph. Carcinogenic o-PD and Cl-PD caused Cu(II)-mediated DNA damage, including 8-oxodG formation, and antioxidant enzyme superoxide dismutase (SOD) enhanced DNA damage. o-PD and Cl-PD caused piperidine-labile and formamidopyrimidine-DNA glycosylase-sensitive lesions at cytosine and guanine residues respectively in the 5′-ACG-3′ sequence, complementary to codon 273, a well-known hotspot of the human p53 tumor suppressor gene. UV–vis spectroscopic studies showed that the spectral change of o-PD and Cl-PD required Cu(II), and addition of SOD enhanced it. This suggested that SOD enhanced the rate of Cu(II)-mediated autoxidation of o-PD and Cl-PD, leading to enhancement of DNA damage. On the other hand, mutagenic but non-carcinogenic NO2-PD induced no DNA damage. These results suggest that carcinogenicity of ortho-phenylenediamines is associated with ability to cause oxidative DNA damage rather than bacterial mutagenicity. [Copyright &y& Elsevier]