The expression profile of microRNAs in a model of 7,12-dimethyl-benz[a]anthrance-induced oral carcinogenesis in Syrian hamster

The animal model of oral squamous cell carcinoma was conducted by tri-weekly (Monday, Wednesday, and Friday) painting with 5% DMBA in acetone. Six Syrian hamsters, including three from the treated group and three from the control group, were used as a training group for microRNA microarray analysis. All microarray data were analyzed by Significance Analysis of Microarrays (SAM) and CLUSTER 3.0 software, and this result was further confirmed by qRT-PCR assay.Seventeen microRNAs were differentially expressed in oral squamous cell carcinoma. Five microRNAs (hsa-miR-21, hsa-miR-200b, hsa-miR-221, hsa-miR-338, and mmu-miR-762) were significantly upregulated and twelve microRNAs (hsa-miR-16, hsa-miR-26a, hsa-miR-29a, hsa-miR-124a, hsa-miR-125b, mmu-miR-126-5p, hsa-miR-143, hsa-miR-145, hsa-miR-148b, hsa-miR-155, hsa-miR-199a, and hsa-miR-203) were down-regulated in cancer tissues. The expression levels of hsa-miR-21 and hsa-miR-16 seen with Stem-loop qRT-PCR were also seen in microarray analysis in all samples.Our findings identified specific microRNA expression in oral squamous cell carcinoma and suggested that microRNAs have a role in oral carcinogenesis.MicroRNAs (miRNAs) are small, noncoding RNAs (~20–22 nucleotides) that have critical functions in various biological processes [1]. These naturally occurring miRNAs function by binding to target mRNAs, resulting in the degradation or translational inhibition of the mRNA, based upon the degree of complementarity with it. First described in 1993 in the nematode Caenorhabditis elegans [2], to date, thousands of miRNAs have been cloned in higher eukaryotes and a number have been shown to play a role in cell proliferation, apoptosis, growth and morphogenesis [3-5]. At present, dysregulation of miRNAs has been shown to be involved in tumor initiation and progression.The explosion of data on miRNAs and cancer has put them in the spotlight over the past few years. Numerous studies have highlighted the suspected role of miRNAs i