Expression variation of OGG1 and HPRT gene and DNA damage in arsenic exposed industrial workers

Arsenic exposure alters redox balance, induces DNA damage, and deregulates many genes. OGG1 gene involved in base repair mechanism, for excision of 8-oxoguanine (8-oxoG) from DNA formed as a result of accumulation of ROS in cell. HPRT gene encode transferase enzymes involved in purine recycling mechanism. The main focus of the study was to evaluate the expression variation in HPRT, OGG1 gene expression, and DNA damage of industrial workers. Blood samples of 300 occupational workers were collected from welding, brick kiln, furniture, pesticide, and paint industry (n = 60/industry) to evaluate the expression variation in HPRT, OGG1 gene expression, and DNA damage in blood cells by comet assay along with age and gender matched 300 control individuals. Blood arsenic content was higher (P<0.001) in an industrial group compared to the control. OGG1 and HPRT expression were (P<0.05) downregulated in exposed workers compared to controls. Spearman correlation analysis showed a significant positive correlation between HPRT vs OGG1 (P< 0.0001) in exposed workers compared to controls. Altered expression of both genes was observed between workers with <25years and >25years of age as well as between workers with <10years and >10year exposure. Reduced expression (P<0.05) of both genes and a high extent of DNA damage was evident in exposed smokers compared to respective non-smokers. DNA fragmentation was higher (P<0.05) in the furniture, welding and brick kiln group compared to control, and other industries. The present study suggests that altered expression of OGG1 and HPRT gene induce oxidative stress, showed a negative impact on the recycling of purines leading to DNA damage which increase the vulnerability of workers to carcinogenicity.

Lead induces DNA damage and alteration of ALAD and antioxidant genes mRNA expression in construction site workers

Oxidative stress and DNA damage are considered as possible mechanisms involved in lead toxicity. To test this hypothesis, DNA damage and expression variations of aminolevulinic acid dehydratase (ALAD), superoxide dismutase 2 (SOD2), and 8-oxoguanine DNA glycosylase 2a (OGG1-2a) genes was studied in a cohort of 100 exposed workers and 100 controls with comet assay and real-time polymerse chain reaction (PCR). Results indicated that increased number of comets was observed in exposed workers versus controls (p < 0.001). After qPCR analysis, significant down-regulation in ALAD (p < 0.0001), SOD2 (p < 0.0001), and OGG1-2a (p < 0.0001) level was observed in exposed workers versus controls. Additionally, a positive spearmen correlation was observed between ALAD versus SOD2 (r = 0.402**, p < 0.001), ALAD versus OGG1-2a (r = 0.235*, p < 0.05), and SOD2 versus OGG1-2a (r = 0.292*, p < 0.05). This study showed that lead exposure induces DNA damage, which is accompanied by an elevated intensity of oxidative stress and expression variation of lead-related gene.