Objective To explore the relationships of arsenic methylation metabolites with the expression of microRNA 548 (mir548) and arsenic (Ⅲ) methyltransferase (AS3MT) mRNA.
Methods Workers exposed to arsenic (exposure group, n=78) from two arsenic smelting plant in Yunnan Province and local residents without occupational arsenic exposure (control group, n=23) were selected by cluster sampling in September 2011. Arsenic species including inorganic arsenic (iAs), monomethylarsonic (MMA), and dimethylarsinic acid (DMA) in urine were determined using atomic absorption spectrophotometer with arsenic speciation pretreatment system to calculate iAs%, MMA%, DMA%, primary methylation index (PMI), and secondary methylation index (SMI). The dominant mRNAs contributed to AS3MT were analyzed by gene analysis software. Real-time polymerase chain reaction (RT-PCR) was performed to detect the expressions of mir548 and AS3MT mRNA in peripheral blood samples. Spearman's correlation analysis was applied to analyze the correlation between the selected indicators.
Results The medians of urinary iAs, MMA, DMA, PMI and MMA% of the exposure group134.54 μg/gCr, 235.88 μg/gCr, 563.57 μg/gCr, 1.61, and 19.01%, respectively were higher than the corresponding medians of the control group2.00 μg/gCr, 1.35μg/gCr, 14.28 μg/gCr, 1.04, and 6.45%, respectively (P<0.05). The SMI and DMA% (3.41 and 61.98%) in the exposure workers were lower than those in the controls (12.31 and 78.01%) (P<0.05). Significant differences were identified in the expressions of mir548 and AS3MT mRNA between the exposed workers (5.08& #177;1.11 and 10.71& #177;2.52) and the controls (6.49& #177;1.68 and 9.19& #177;2.11) (both P<0.01). Negative correlations of mir548 were found with AS3MT mRNA, iAS, MMA, DMA, or MMA%. There existed close positive correlations between AS3MT mRNA and iAs, MMA, DMA, MMA%, and also between mir548 and DMA% (P<0.01).
Conclusion Negative correlations are identified between the expressions of mir548 and AS3MT mRNA, and both show significant associations with the concentrations or proportions of various arsenic methylated metabolites.
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