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Simple Summary: Hypoxia drives the dysregulation of RNA molecules in canine oral melanoma (COM), influencing tumor progression and metastasis. While hypoxia-associated miRNAs have been explored, this study focused on other non-coding RNAs (ncRNAs) using NGS and qPCR. The present study revealed significant hypoxia-regulated alterations in ncRNA expression profiles, highlighting ENSCAFT00000084705.1 as consistently downregulated in COM tissues and cell lines compared to healthy tissue. Notably, its absence in plasma and extracellular vesicles suggests limited biomarker potential. This study provides evidence of transcriptional changes in ncRNAs except for miRNAs in COM, highlighting ENSCAFT00000084705.1 as a promising candidate for future investigations into the role of the transcriptome in the hypoxia-driven progression of this aggressive cancer. Hypoxia contributes to tumor progression and metastasis, and hypoxically dysregulated RNA molecules may, thus, be implicated in poor outcomes. Canine oral melanoma (COM) has a particularly poor prognosis, and some hypoxia-mediated miRNAs are known to exist in this cancer; however, equivalent data on other hypoxically dysregulated non-coding RNAs (ncRNAs) are lacking. Accordingly, we aimed to elucidate non-miRNA ncRNAs that may be mediated by hypoxia, targeting primary-site and metastatic COM cell lines and clinical COM tissue samples in next-generation sequencing (NGS), with subsequent qPCR validation and quantification in COM primary and metastatic cells and plasma and extracellular vesicles (EVs) for any identified ncRNA of interest. The findings suggest that a number of non-miRNA ncRNA species are hypoxically up- or downregulated in COM. We identified one ncRNA, the long ncRNA fragment ENSCAFT00000084705.1, as a molecule of interest due to its consistent downregulation in COM tissues, hypoxically and normoxically cultured primary and metastatic cell lines, when compared to the oral tissues from healthy dogs. However, this molecule was undetectable in plasma and plasma EVs, suggesting that its expression may be tumor tissue-specific, and it has little potential as a biomarker. Here, we provide evidence of hypoxic transcriptional dysregulation for ncRNAs other than miRNA in COM for the first time and suggest that ncRNA ENSCAFT00000084705.1 is a molecule of interest for future research on the role of the transcriptome in the hypoxia-mediated progression of this aggressive cancer. [ABSTRACT FROM AUTHOR]

Hepatocellular adenoma (HCA) and hepatocellular carcinoma (HCC) can be difficult to differentiate but must be diagnosed correctly as treatment and prognosis for these tumors differ markedly. Relevant diagnostic biomarkers are thus needed, and those identified in dogs may have utility in human medicine because of the similarities between human and canine HCA and HCC. A tRNA-derived fragment (tRF), tRNA-Val, is a promising potential biomarker for canine mammary gland tumors but has not previously been investigated in hepatic tumors. Accordingly, we aimed to elucidate the potential utility of tRNA-Val as a biomarker for canine HCA and HCC using clinical samples (tumor tissue and plasma extracellular vesicles [EVs]) and tumor cell lines with qRT-PCR assays. We also investigated relevant functions and signaling pathways with bioinformatic analyses (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes). tRNA-Val was markedly downregulated in HCC tumor tissue versus HCA tumor tissue and normal liver tissue, and a similar trend was shown in plasma EVs and HCC cell lines versus healthy controls. Based on areas under the receiver operating characteristic curves (AUCs), tRNA-Val significantly distinguished HCC (AUC = 1.00, p = 0.001) from healthy controls in plasma EVs and HCC from HCA (AUC = 0.950, p = 0.01). Bioinformatics analysis revealed that tRNA-Val may be primarily involved in DNA repair, mRNA processing, and splicing and may be linked to the N-glycan and ubiquitin-mediated proteasome pathways. This is the first report on the expression of tRNA-Val in canine HCC and HCA and its possible functions and signaling pathways. We suggest that tRNA-Val could be a promising novel biomarker to distinguish canine HCC from HCA. This study provides evidence for a greater understanding of the role played by tRNA-Val in the development of canine HCC. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) dysregulation contribute the cancer pathogenesis. However, the miRNA profile of canine oral melanoma (COM), one of the frequent malignant melanoma in dogs is still unrevealed. The aim of this study is to reveal the miRNA profile in canine oral melanoma. MiRNAs profile of oral tissues from normal healthy dogs and COM patients were compared by next-generation sequencing. Along with tumour suppressor miRNAs, we report 30 oncogenic miRNAs in COM. The expressions of miRNAs were further confirmed by quantitative real-time PCR (qPCR). Pathway analysis showed that deregulated miRNAs impact on cancer and signalling pathways. Three oncogenic miRNAs targets (miR-450b, 301a, and 223) from human study also were down-regulated in COM and had a significant negative correlation with their respective miRNA. Furthermore, we found that miR-450b expression is higher in metastatic cells and regulated MMP9 expression through a PAX9-BMP4-MMP9 axis. In silico analysis indicated that miR-126, miR-20b, and miR-106a regulated the highest numbers of differentially expressed transcription factors with respect to human melanoma. Chromosomal enrichment analysis revealed the X chromosome was enriched with oncogenic miRNAs. We comprehensively analyzed the miRNA's profile in COM which will be a useful resource for developing therapeutic interventions in both species. [ABSTRACT FROM AUTHOR]