P16 hypermethylation is a potential cause of oxidative stress due to long-term exposure to hexavalent chromium

Abstract Exposure to hexavalent chromium can result in severe health issues such as skin irritation, respiratory irritation, and cancer. This study aimed to examine the potential link between occupational exposure to hexavalent chromium, oxidative stress, and changes in gene methylation levels. This study measured biomarkers of oxidative stress (malondialdehyde, glutathione, 8-hydroxy-2'- deoxyguanosine) and the methylation status at the promoter of cyclin-dependent kinase inhibitor 2A (p16) gene, known for its frequent methylation-mediated silencing in human cancers. A total of 192 workers (99 males and 93 females) from electroplating factories exposed to hexavalent chromium were included, along with 80 controls (35 males and 45 females). The results showed that electroplating workers had a lower glutathione level but a higher methylation status of p16 gene promoter compared to the control group. This study suggests that the methylation status of p16 could serve as a biomarker for the epigenetic effects of chromium exposure, and it reveals a negative association between oxidative stress levels and the methylation of tumor suppressor p16.