Differential expression of cancer associated plasma miRNAs in the ordnance factory workers, exposed to 2,4,6-Trinitrotoluene

Objectives: To determine differential expression of microRNAs (miRNAs) in plasma of 2, 4, 6-Trinitrotoluene (TNT) exposed ordnance factory workers.

Methods: A case control study was conducted at the Department of Toxicology, Armed Forces Institute of Pathology, Rawalpindi from July to December 2020. A total 30 subjects were recruited from an ordnance factory that were directly exposed to TNT and 120 non-exposed individuals from non-factory healthy population. Plasma levels of five miRNAs including miRNA-let-7a-2, miRNA-34a-1, miRNA-21-2, miRNA-106b-1, miRNA-122a-1 were measured by quantitative real-time polymerase chain reaction (RT-PCR).

Results: Micro RNAs showed a wide range of Ct (cycle threshold) values ranging from 23.48 to 41.94. Among the five miRNAs let-7a-2 and miRNA-122a-1 displayed relatively high expression with Ct values ranging from 26.58 ± 2.25 to 27.18 ± 0.80 respectively. Relative fold change expression for all five miRNAs of exposed individuals were found high (p <0.0001) vs non-exposed. Dividing fold change expression of exposed individuals into two groups as ≤ 10 and > 10, the individuals having ≤ 10-fold change expression were19 (63.3%) in miRNA-let-7a-2, 30 (100%) in miRNA-34a-1 and 23 (76.7%) in miRNA-122a-1 while in miRNA-21-2 and miR-106b-1, 23 (76.7%) and 18(60%) individuals had > 10-fold change expression respectively. Among the five miRNAs in exposed individuals, miRNA-let-7a-2, miR-21-2, miR-106b-1 and miR-122a-1 were found highly expressed with fold change expression > 10 (p <0.0001). No significant association was found between miRNAs expression levels with age and working duration.

Conclusion: The study shows upregulation of all five miRNAs in TNT exposed subjects with no significant association of expression levels with age and working duration.