of target genes ([@b8-ol-0-0-7146]), although they are usually only partially complementary to the target ([@b9-ol-0-0-7146]). miRNAs regulate \~30% of the human genes associated with proliferation, apoptosis, metastasis, cell immunity and differentiation ([@b10-ol-0-0-7146]). Each miRNA is able to regulate several hundred mRNAs, and each mRNA may be the target of several miRNAs. Therefore, a regulatory control network exists between miRNAs and mRNAs ([@b11-ol-0-0-7146]). Furthermore, miRNAs have been associated with several types of tumors, including non-small cell lung cancer, colon and esophageal cancer, and FTC ([@b12-ol-0-0-7146]--[@b14-ol-0-0-7146]). However, there are few studies of specific miRNA and mRNA analyses of follicular thyroid tumors.

Several microarray studies have already described the differentially expressed genes (DEGs) between malignant and benign thyroid nodules. However, these studies have several restrictions, including the fact that the samples are limited, they contain significant false-negatives, and they require external analysis at an offsite company laboratory ([@b15-ol-0-0-7146]--[@b17-ol-0-0-7146]). Certain studies have aimed to reveal the potential miRNAs associated with follicular thyroid tumors ([@b18-ol-0-0-7146]).

In the present study, an integrated analysis of differentially expressed miRNAs (DEMs) and DEGs between FTC and FA was performed. A Gene Ontology (GO) analysis of the DEGs was performed. A total of 36 miRNA-gene pairs were identified between the DEGs and the target genes of the DEMs. A miRNA-mRNA network analysis was then performed to additionally investigate the pathogenesis of FTC.

Materials and methods
=====================

### Analysis of mRNA and miRNA profiling datasets

Expression profile datasets containing mRNA and miRNA were acquired from the Gene Expression Omnibus (GEO; <http://www.ncbi.nlm.nih.gov/geo/>). The expression profiling data of GSE29315 (Tomas *et al*, unpublished) are mRNA profiling data, originally obtained from a cohort of 9 FTC and 17