Background: Dysregulation of miRNAs is associated with the development of non-small
cell lung cancer (NSCLC). It is imperative to study the dysregulation of miRNAs by cigarette smoke
which will affect their targets, either leading to the overexpression of oncoproteins or downregulation
of tumor suppressor proteins.
Objective and Methods: In this study, we carried out miRNA sequencing and SILAC-based proteomic
analysis of H358 cells chronically exposed to cigarette smoke condensate. Using bioinformatics
analysis, we mapped the dysregulated miRNAs to differentially expressed target proteins identified in
our data. Gene ontology-based enrichment and pathway analysis was performed using the deregulated
targets to study the role of cigarette smoke-mediated miRNA dysregulation in NSCLC cell line.
Results: miRNA sequencing resulted in the identification of 208 miRNAs, of which 6 miRNAs were
found to be significantly dysregulated (2 fold, Log Base 2; p-value ≤ 0.05) in H358-Smoke cells. Proteomic
analysis of the smoke exposed cells compared to the untreated parental cells resulted in the
quantification of 2,610 proteins, of which 690 proteins were found to be differentially expressed (fold
change ≥ 2). Gene ontology based analysis of target proteins revealed enrichment of proteins driving
metabolism and a decrease in expression of proteins associated with immune response in the cells exposed
to cigarette smoke. Pathway study using Ingenuity Pathway Analysis (IPA) revealed activation
of NRF2-mediated oxidative stress response and actin-cytoskeleton signaling, and repression of protein
kinase A signaling in H358-Smoke cells. We also identified 5 novel miRNAs in H358-Smoke
cells using unassigned reads of small RNA-Seq dataset.
Conclusion: In summary, this study indicates that chronic exposure to cigarette smoke leads to widespread
dysregulation of miRNAs and their targets, resulting in signaling aberrations in NSCLC cell
line. The miRNAs and their targets identified in the study need to be further investigated to explore
their role as potential therapeutic targets and/or molecular markers in NSCLC especially in smokers.