Differential expression of microRNAs and their target genes in non-small-cell lung cancer

MicroRNAs (miRNAs) are single-stranded RNA species that constitute a class of non-coding RNAs, and are emerging as key regulators of gene expression. Since each miRNA is capable of regulating multiple genes, miRNAs are attractive markers for studies of coordinated gene expression. In this study, we investigated miRNA expression profiling using a massively parallel sequencing technique to compare non-small-cell lung cancer (NSCLC) tissue and normal lung tissue. Lung cancer tissue and normal lung tissue were obtained from nine NSCLC patients. RNA isolated from these samples was processed using RNA sequencing (RNA Seq) and the HiSeq 2000 system. Differentially expressed miRNAs and mRNAs were analyzed using a t-test. We selected target pairs that showed a negative correlation among significantly differentially expressed miRNAs and their putative target mRNAs using miRBase Targets. The differences in the expression levels of 222 miRNAs and 1,597 genes were statis- tically significant, as indicated by an absolute fold change ≥1.5 and P<0.05. miR‑577, miR‑301b, miR‑944, miR‑891a and miR‑615‑3p were generally upregulated, and miR‑338‑3p was generally downregulated. miRNA-mRNA target pair analysis revealed that 49 miRNAs had 696 target mRNAs. There were significantly differentially expressed miRNAs and mRNAs between lung cancer and normal tissue. Further investigation of miRNAs and their target genes is warranted to better under- stand NSCLC.