Reactive oxygen species (ROS) are known to promote mesothelial carcinogenesis that is closely associated with asbestos fibers and inflammation. Epithelial to mesenchymal cell transition (EMT) is an important process involved in the progression of tumors, providing cancer cells with aggressiveness. The present study was performed to determine if EMT is induced by H 2 O 2 in human malignant mesothelioma (HMM) cells. Cultured HMM cells were treated with H 2 O 2 , followed by measuring expression levels of EMT-related genes and proteins. Immunohistochemically, TWIST1 expression was confined to sarcomatous cells in HMM tissues, but not in epithelioid cells. Treatment of HMM cells with H 2 O 2 promoted EMT, as indicated by increased expression levels of vimentin, SLUG and TWIST1, and decreased E-cadherin expression. Expression of stemness genes such as OCT4, SOX2 and NANOG was also significantly increased by treatment of HMM cells with H 2 O 2 . Alteration of these genes was mediated via activation of hypoxia inducible factor 1 alpha (HIF-1α) and transforming growth factor beta 1 (TGF-β1). Considering that treatment with H 2 O 2 results in excess ROS, the present study suggests that oxidative stress may play a critical role in HMM carcinogenesis by promoting EMT processes and enhancing the expression of stemness genes.

The role of microRNAs (miRNAs) as a post-transcriptional gene regulator has been elucidated in a broad range of organisms including domestic animals. Characterization of miRNAs in normal tissues is an important step to investigate the functions of miRNAs in various physiological and pathological conditions. Using Illumina Next Generation Sequencing (NGS) technology, we identified a total of 292 known and 329 novel miRNAs in normal horse tissues including skeletal muscle, colon and liver. Distinct sets of miRNAs were differentially expressed in a tissue-specific manner. The miRNA genes were distributed across all the chromosomes except chromosomes 29 and 31 in the horse reference genome. In some chromosomes, multiple miRNAs were clustered and considered to be polycistronic transcript. A base composition analysis showed that equine miRNAs had a higher frequency of A+U than G+C. Furthermore, U tended to be more frequent at the 5′ end of miRNA sequences. This is the first experimental study that identifies and characterizes the global miRNA expression profile in normal horse tissues. The present study enriches the horse miRNA database and provides useful information for further research dissecting biological functions of miRNAs in horse.

Purpose: To identify laminitis‐specific plasma microRNAs in a horse Method and materials: In order to induce laminitis experimentally, oligofructose was administered to a horse through nasogastric tube. Peripheral blood was collected from the jugular vein at the time of pre/post induction of laminitis. After euthanasia, various tissues including laminae were collected from the horse. Total RNA was extracted and subjected to the reverse transcription to cDNA. The cDNA products of the small RNA fragments ranging from 40bp to 60bp were sequenced directly using Illumina HiSeq 2000 sequencer. Results: A total of 288 miRNAs were identified in laminar tissues and 262 miRNAs were identified in the plasma of horse with laminitis. Fifteen miRNAs were identified as laminitis‐specific plasma miRNAs, based on the following criteria: laminar tissue‐specific expression compared to other tissues and significant increase of the plasma miRNA level after the induction of laminitis. Conclusions: The present study revealed a subset of plasma miRNAs specific to horse laminitis, suggesting the potential value of the miRNAs as a biomarker for the diagnosis of equine laminitis. Grant Funding Source: Supported by Bio‐industry Technology Development Program of iPET, Ministry of Agriculture, Korea