Assessment of circulating miR-20b, miR-221, and miR-155 in occupationally lead-exposed workers of North-Western India

Lead (Pb), a toxic heavy metal, is capable of inducing several adverse health effects following its accumulation in the body. Lead is a potential carcinogen, capable of causing multisystem alterations. Recent reports identify small regulatory RNA molecules-miRNAs-which show differential expression in individuals exposed to similar levels of lead. These miRNAs can become potential molecular biomarkers of lead toxicity in the future and may unravel the possible molecular pathways through which this metal may exert its toxic manifestations. The present study aimed to assess the circulating levels of miRNA-20b, 221, and 155 in occupationally lead-exposed workers and correlate them with blood lead levels. One hundred ten participants working in various factories of Jodhpur and 97 participants not occupationally exposed to lead were recruited after obtaining due informed consent. Blood lead level (BLL) was estimated by graphite furnace atomic absorption spectrophotometry (GF-AAS). Circulating miRNAs were isolated from serum by Qiagen miRNA isolation kit and converted to cDNA by commercial kit. Expression profiles of miR-20b, miR-221, and miR-155 were performed in RT-PCR using Qiagen miRNA PCR assays. The blood lead level (mean +/- SD) of occupationally lead-exposed subjects was 6.94 +/- 11.96 mu g/dL while that of non-exposed was 2.39 +/- 4.66 mu g/dL. Out of the three miRNAs, miR-155 and miR-221 were significantly upregulated, while miR-20b did not show significant difference among study groups. The fold change of miR-20b, miR-221 and miR-155 expression were 1.08, 2.71 and 2.07 respectively. Functional analysis revealed that these miRNAs have the potential to trigger various genes and cellular pathways. The findings of our study highlight the importance of miRNA dysregulation in lead-exposed individuals that may contribute to the systemic effects of lead toxicity.

Automated summary

The study found that miR-155 and miR-221 were significantly upregulated in occupationally lead-exposed workers, while miR-20b showed no significant difference. These miRNAs have the potential to trigger various genes and cellular pathways, highlighting the importance of miRNA dysregulation in the systemic effects of lead toxicity.