Biomethylation metabolism study of arsenite in SCC-7 cells by reversed phase ion pair high performance liquid chromatography-inductively coupled plasma-mass spectrometry.

Arsenite (As(III)) has been considered as a human carcinogen associated with many human cancers especially skin cancer. Elucidation of the transformed species of As(III) during its metabolism in cells is beneficial for evaluation of its bioeffect. In this work, a hyphenated method of reversed phase ion pair high performance liquid chromatography - inductively coupled plasma mass spectrometry (RP-IP-HPLC-ICP-MS) equipped with collision/reaction cell technology (CCT) was developed for speciation of As(III) and its metabolites (arsenate [As(V)], monomethylarsonic acid [MMA(V)], and dimethylarsinic acid [DMA(V)]) in SCC-7 cells. The developed analytical method exhibits low limits of detection for interest arsenic species in the range of 14-27 ng/L and wide linear range up to four orders of magnitude, providing a sensitive tool for arsenic metabolites analysis and further understanding the metabolism of As(III) in SCC-7 cells. The effect of exposure time, exposure concentrations and elimination time on the arsenic species and total arsenic in SCC-7 cells incubated by As(III) were systematically studied. At low exposure concentrations (< 5 μM), large proportion of intracellular As(III) transformed to methylated metabolites, and the final methylated metabolite DMA(V), which could not be completely removed from the cells in the elimination process, is considered to play as the primary carcinogen. While at high exposure concentrations (> 5 μM), most of intracellular As(III) probably bound to biomacromolecules rather than followed biomethylation process, exhibiting different metabolism.