Analysis of microRNA and mRNA expression profiles highlights alterations in modulation of the MAPK pathway under octanal exposure.

Previous environmental microRNA (miRNA) studies have investigated a limited number of candidate miRNAs and have not evaluated functional effects on gene expression. In this study, we aimed to identify octanal (OC)-sensitive miRNAs and to characterize the relationships between miRNAs and expression of candidate genes involved in OC-induced toxicity. Microarray analysis identified 15 miRNAs that were differentially expressed in OC-exposed A549 human alveolar cells. Integrated analyses of miRNA and mRNA expression profiles identified significant miRNA-mRNA anti-correlations. GO analysis of 101 putative target genes showed that the biological category 'MAPK signaling pathway' was prominently annotated. Moreover, we detected increased phosphorylation of p38 MAPK in the OC-exposed group. By integrating the transcriptome and microRNAome, we provide evidence that OC can affect MAPK-induced toxicity signaling. Therefore, this study demonstrates the added value of an integrated miRNA-mRNA approach for identifying molecular events induced by environmental pollutants in an in vitro human model.