Objective To study the relationship between P53 gene damage and urinary monomethylarsonic acid levels in people occupationally exposed to arsenic, and to understand genotoxicity of arsenic.
Methods Ninety-five workers exposed to arsenic in two arsenic plants were recruited as the exposure group, and 55 residents without arsenic exposure as the control group. Their peripheral blood and urina sanguinis were collected. Inorganic arsenic (iAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine were detected by hydride generation-atomic absorption spectrometry to calculate primary and secondary methylation indices. Exon 5 and 8 of P53 gene were amplified by real-time polymerase chain reaction to calculate efficiency of modified templates and damage index using cycle threshold.
Results The concentrations of iAs, MMA and DMA in the exposure group were significantly higher than that in the controls. The secondary methylation index in the exposed population was significantly lower than in the controls. The damage index of exon 5 and 8 of P53 gene in the exposure group was significantly higher than that in the control group. A positive correlation was found between the damage index of exon 5 and the primary methylation index, and a negative one was found between the damage index of exon 5 and the secondary methylation index.
Conclusion There is a significant effect of arsenic on secondary methylation index of arsenic-exposed workers. The results suggest that monomethylarsonic acid may play an important role in the damage of exon 5 of P53 gene.
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