Arsenic exposure and cancer-related biomarkers in indigenous populations in Bolivia – modification by arsenic metabolism efficiency

Abstract

Inorganic arsenic is a known carcinogen. Telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) in peripheral blood may serve as biomarkers for genotoxicity and cancer risk. Our aim is to assess if arsenic exposure influences TL and mtDNAcn in women living around Lake Poopó (Bolivia) from two ethnicities (Aymara-Quechua and Uru). Arsenic exposure was evaluated as the sum of arsenic metabolite concentrations in urine (U-As) measured by high-performance liquid chromatography online with hydride generation and inductively coupled plasma-mass spectrometry (HPLC-HG-ICP-MS), and as total arsenic in blood (B-As) measured by ICP-MS. Efficiency of arsenic metabolism was evaluated using the relative fractions of urinary metabolites, and arsenic methylating genetics (AS3MT rs3740393 and rs1046778) measured by TaqMan allelic discrimination or chip-based genotyping. TL and mtDNAcn were determined in blood by real-time PCR. Our results show that arsenic exposure (assessed as U-As and B-As) was associated with longer TL and higher mtDNAcn in this study population, and the associations were modified by arsenic metabolism capacity and AS3MT genotype.