nNav1.5 expression is associated with glutamate level in breast cancer cells

Abstract Background: Glutamate and voltage-gated sodium channels, both have been the target of intense investigation for its involvement in carcinogenesis and progression of malignant disease. Breast cancer with increased level of glutamate often metastasize to other organs (especially bone), whilst re-expression of 'neonatal' Nav1.5, nNav1.5 in breast cancer is known to promote cell invasion in vitro, metastasis in vivo and positive lymph node metastasis in patients. Methods: In this study, the role of nNav1.5 in regulating glutamate level in human breast cancer cells was examined using pharmacological approach (VGSCs specific blocker, TTX, glutamate release inhibitor, riluzole and siRNA-nNav1.5). Effect of these agents were evaluated based on endogenous and exogenous glutamate concentration using glutamate fluorometric assay, mRNA expression of nNav1.5 using qPCR and finally, invasion using 3D culture assay. Results: Endogenous and exogenous glutamate levels were significantly higher in aggressive human breast cancer cells, MDA-MB-231 cells compared to less aggressive human breast cancer cells, MCF-7 and non-cancerous human breast epithelial cells, MCF-10A. Treatment with TTX to MDA-MB-231 cells resulted in significant reduction of endogenous and exogenous glutamate levels corresponded with significant suppression of cell invasion. Subsequently, downregulation of nNav1.5 gene was observed in TTX-treated cells. Conclusions: An interesting link between nNav1.5 expression and glutamate level in aggressive breast cancer cells was detected and requires further investigation.

Compound Heterozygous SCN5A Mutations in a Toddler - Are they Associated with a More Severe Phenotype? / Heterozigose Composta no Gene SCN5A em Criança - Há Associação com Gravidade da Doença?

Abstract Compound heterozygosity has been described in inherited arrhythmias, and usually associated with a more severe phenotype. Reports of this occurrence in Brugada syndrome patients are still rare. We report a study of genotype-phenotype correlation after the identification of new variants by genetic testing. We describe the case of an affected child with a combination of two different likely pathogenic SCN5A variants, presenting sinus node dysfunction, flutter and atrial fibrillation, prolonged HV interval, spontaneous type 1 Brugada pattern in the prepubescent age and familiar history of sudden death.

Resumo A heterozigose composta é descrita em arritmias hereditárias, geralmente associada a um fenótipo mais grave. Relatos dessa ocorrência em pacientes com síndrome de Brugada ainda são raros. Neste estudo, descrevemos o caso de uma criança com a combinação de duas novas variantes distintas no gene SCN5A, apresentando disfunção do nó sinusal, flutter e fibrilação atrial, intervalo HV prolongado, padrão tipo 1 espontâneo de Brugada na idade pré-puberal e história familiar de morte súbita.