RESUMEN
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.
Asunto(s)
Biomarcadores de Tumor , Carcinoma Hepatocelular , Neoplasias Hepáticas , Animales , Perros , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/veterinaria , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/veterinaria , Neoplasias Hepáticas/patología , Biomarcadores de Tumor/genética , Enfermedades de los Perros/genética , Enfermedades de los Perros/diagnóstico , Adenoma de Células Hepáticas/genética , Adenoma de Células Hepáticas/veterinaria , Adenoma de Células Hepáticas/patología , Adenoma de Células Hepáticas/metabolismo , Adenoma de Células Hepáticas/diagnóstico , Regulación Neoplásica de la Expresión Génica , Diagnóstico Diferencial , Línea Celular Tumoral , FemeninoRESUMEN
In this study, we report the metabolic consequences of the m.1630 Aâ¯>â¯G variant in fibroblasts from the symptomatic proband affected with the mitochondrial encephalomyopathy lactic acidosis and stroke-like episode Syndrome and her asymptomatic mother. By long-range PCR followed by massively parallel sequencing of the mitochondrial genome, we accurately measured heteroplasmy in fibroblasts from the proband (89.6%) and her mother (94.8%). Using complementary experimental approaches, we show a functional correlation between manifestation of clinical symptoms and bioenergetic potential. Our mitochondrial morphometric analysis reveals a link between defects of mitochondrial cristae ultrastructure and symptomatic status. Despite near-homoplasmic level of the m.1630Aâ¯>â¯G variant, the mother's fibroblasts have a normal OXPHOS metabolism, which stands in contrast to the severely impaired OXPHOS response of the proband's fibroblasts. The proband's fibroblasts also exhibit glycolysis at near constitutive levels resulting in a stunted compensatory glycolytic response to offset the severe OXPHOS defect. Whole exome sequencing reveals the presence of a heterozygous nonsense VARS2 variant (p.R334X) exclusively in the proband, which removes two thirds of the VARS2 protein containing key domains interacting with the mt-tRNAval and may play a role in modulating the penetrance of the m.1630Aâ¯>â¯G variant despite similar near homoplasmic levels. Our transmission electron microscopy study also shows unexpected ultrastructural changes of chromatin suggestive of differential epigenomic regulation between the proband and her mother that may explain the differential OXPHOS response between the proband and her mother. Future study will decipher by which molecular mechanisms the nuclear background influences the penetrance of the m.1630 Aâ¯>â¯G variant causing MELAS.
Asunto(s)
Fibroblastos/patología , Variación Genética , Síndrome MELAS/genética , Madres , Penetrancia , Enfermedades Asintomáticas , Metabolismo Energético , Femenino , Fibroblastos/metabolismo , Genoma Mitocondrial , Glucólisis , Antígenos HLA/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Microscopía Electrónica de Transmisión , Persona de Mediana Edad , Mitocondrias/patología , Mitocondrias/ultraestructura , Mutación Puntual , Valina-ARNt Ligasa/genética , Adulto JovenRESUMEN
The DNA sequences of the mitochondrial (mt) 12S rRNA and tRNA(Val) genes were characterized for 82 blacklegged ticks (Ixodes scapularis) that were genetically identical for Domains IV and V of the mt 16S rRNA gene. Thirty-one haplotypes, differed in sequence by 1-9 bp, were detected among the 82 ticks. Most nucleotide alterations in DNA sequence did not affect the stability of the secondary structures of the RNAs. The magnitude of the DNA sequence variation in the mt 12S rRNA and tRNA(Val) genes among blacklegged ticks suggests that this region of the mitochondrial genome has potential as a genetic marker for examining the population genetics and phylogeography of I. scapularis.