ABSTRACT
Objective To examine the possibility that a candidate causal species of the skin and lung tumor promotion induced by exposure to dimethylarsinic acid(DMAv)and dimethylarsinous acid(DMAⅢ),caused by the induction of oxidative stress in mice.Methods Two stages lung tumotigensis animal model induced by lung tumor initiator(4-nitroquinoline 1-oxide,4NQO)and promoter(DMAv)in ddY mice,was used to examine the effect of(-)epigallocatechin gallate(EGCG)on DMAv promoting lung tumorigenesis.Two stages skin tumorigenesis animal model induced by skin tumor initiator[dimethylbenz(α)anthracene,DMBA]and promoter(DMAⅢ)in hairless mice.was used to examine the effects of DMAⅢ in skin tumorigenesis and histopathology.The goxo-2'-deoxyguanosine (8-oxodG)in lung and epidermis were analyzed by HPLC.Results The incidence of lung tumors and 8-oxodG level of lung tissue decreased significantly in 4NQO+DMAv+EGCG group.compared with 4NQO+DMAv group (0.89±0.30 vs 4.00±0.82,1.21±0.09 vs 1.53±0.32,P＜0.01).The incidence of severe keratosis in DMBA+ DMIⅢ group was more than that in DMBA group(25 vs 10,P＜0.05).An significant elevation of 8-oxodG in epidermis was observed in 0.5 h[(1.67±0.17)/105 dG],1.0 h[(1.62±012)/105 dG],2.0 h[(1.66±023)/105dG], 3.0 h[(1.60±0.15)/105 dG],compared with 0 h[(1.25±0.11)/105 dG],being significant(P＜0.05).Conclusion tumor promotion due to DMAv administration is mediated by DMAⅢ through the induction of oxidative stress.