Assessing the responses of miRNA-200b and miRNA-429 in cyanide poisoning cases

Abstract

Background: Cyanide toxicity disrupts cellular respiration by inhibiting mitochondrial cytochrome oxidase a3, resulting in cellular hypoxia. The cell’s response to hypoxia is mediated by hypoxia-inducible factors (HIFs) and associated microRNAs (hypoxamiRs). Among these, miR-429 and miR-200b have been implicated in the regulation of HIFs and were found to be upregulated during acute hypoxic conditions. However, their specific roles in cyanide-induced hypoxia remain poorly understood.

Objective: The aim of this study was to evaluate the expression of miR-429 and miR-200b in postmortem peripheral blood collected from cyanide poisoning fatalities.

Methods: Postmortem blood was obtained from five cyanide poisoning cases and five nonasphyxial controls; for all cases, the postmortem interval was < 24 hours. After total RNA was extracted from the blood, 10 ng of RNA was reverse-transcribed into complementary DNA using MultiScribe™ Reverse Transcriptase. The expression of miR-429 and miR-200b was quantified using the QuantStudio™ 5 system and TaqMan™ MicroRNA assays. Relative miRNA expression was calculated using the 2 ΔΔCTmethod and compared using the Mann–Whitney U test. One cyanide case was excluded because of low RNA quality.

Results: Toxicological screening confirmed lethal cyanide concentrations consistent with oral ingestion. Common autopsy findings included pulmonary edema and renal tubular injury, with no definitive cerebral hypoxic changes. The comparative analysis revealed that miR-429 and miR-200b tended to be higher in the cyanide group (n = 4) than in the controls (n = 5), but the differences were not statistically significant (miR- 429: P = 0.31; miR-200b: P= 0.22).

Conclusion: This study identified higher expressions of miR-429 and miR-200b in cyanide poisoning cases compared with controls, which was consistent with previous evidence linking these microRNAs to hypoxic responses. Although the increase in expression did not meet statistical thresholds, the observed patterns indicate that these microRNAs may be involved in cyanide-induced hypoxia. These preliminary findings underscore the need for further investigation of larger, well-defined cohorts to fully elucidate the diagnostic and mechanistic roles of miR-429 and miR-200b in cyanide toxicity.