RESUMO
Mitochondria are central key players in cell metabolism, and mitochondrial DNA (mtDNA) instability has been linked to metabolic changes that contribute to tumorigenesis and to increased expression of pro-tumorigenic genes. Here, we use melanoma cell lines and metastatic melanoma tumors to evaluate the effect of mtDNA alterations and the expression of the mtDNA packaging factor, TFAM, on energetic metabolism and pro-tumorigenic nuclear gene expression changes. We report a positive correlation between mtDNA copy number, glucose consumption, and ATP production in melanoma cell lines. Gene expression analysis reveals a down-regulation of glycolytic enzymes in cell lines and an up-regulation of amino acid metabolism enzymes in melanoma tumors, suggesting that TFAM may shift melanoma fuel utilization from glycolysis towards amino acid metabolism, especially glutamine. Indeed, proliferation assays reveal that TFAM-down melanoma cell lines display a growth arrest in glutamine-free media, emphasizing that these cells rely more on glutamine metabolism than glycolysis. Finally, our data indicate that TFAM correlates to VEGF expression and may contribute to tumorigenesis by triggering a more invasive gene expression signature. Our findings contribute to the understanding of how TFAM affects melanoma cell metabolism, and they provide new insight into the mechanisms by which TFAM and mtDNA copy number influence melanoma tumorigenesis.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica/genética , Melanoma/genética , Melanoma/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Aminoácidos/genética , Aminoácidos/metabolismo , Carcinogênese/genética , Linhagem Celular Tumoral , Variações do Número de Cópias de DNA/genética , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Regulação para Baixo/genética , Glutamina/genética , Glutamina/metabolismo , Glicólise/genética , Humanos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Regulação para Cima/genética , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
BACKGROUND AND PURPOSE: Cranial nerve abnormalities might be observed in hemifacial microsomia and microtia (oculo-auriculo-vertebral spectrum), but the rate, features, and relationship with functional impairment or phenotype severity have not yet been defined. This study aimed at investigating absence/asymmetry, abnormal origin, morphology and course of cranial nerves, and presence/asymmetry of the foramen ovale and inferior alveolar nerve canal in a cohort of oculo-auriculo-vertebral spectrum patients. MATERIALS AND METHODS: Twenty-nine patients with oculo-auriculo-vertebral spectrum (mean age, 7 years; age range, 0.2-31 years; 12 females) underwent brain MR imaging, CT, and neurologic evaluation; 19 patients had a more severe phenotype (Goldenhar syndrome). RESULTS: Cranial nerve abnormalities were detected only in patients with Goldenhar syndrome (17/19, bilaterally in 8) and were involved the second (4/19), third (1/18), fifth (11/19), sixth (8/16), seventh (11/18), and eighth (8/18) cranial nerves. Multiple cranial nerve abnormalities were common (11/17). Eleven patients showed bone foramina abnormalities. Trigeminal and facial nerve dysfunctions were common (44% and 58%, respectively), especially in patients with Goldenhar syndrome. Trigeminal abnormalities showed a good correlation with ipsilateral dysfunction (P = .018), which further increased when bone foramina abnormalities were included. The facial nerve showed a trend toward correlation with ipsilateral dysfunction (P = .081). Diplopia was found only in patients with Goldenhar syndrome and was associated with third and sixth cranial nerve abnormalities (P = .006). CONCLUSIONS: Among patients with oculo-auriculo-vertebral spectrum, cranial nerve morphologic abnormalities are common, correlate with phenotype severity, and often entail a functional impairment. The spectrum of cranial nerve abnormalities appears wider than simple hypo-/aplasia and includes an anomalous cisternal course and partial/complete fusion of diverse cranial nerves.
