Valor biomarcador de glicanos O-GaINAc no controlo terapêutico de NMIBC

Abstract

A deficiência em 3-hidroxiacil-CoA desidrogenase de ácidos gordos de cadeia longa (LCHAD) é uma desordem da oxidação lipídica mitocondrial que apesar de rara está associada a um mau prognóstico devido às suas graves consequências clínicas. Apesar de a implementação dos programas de rastreio neonatal em alguns países desenvolvidos, incluindo Portugal, ter contribuído para uma melhor compreensão das doenças metabólicas e para a prevenção das suas consequências, os mecanismos fisiopatológicos subjacentes à LCHAD ainda são pouco compreendidos. No sentido de contribuir para a elucidação destes mecanismos, avaliou-se a plasticidade mitocondrial em resposta à deficiência em LCHAD. Assim, foram isoladas mitocôndrias de culturas de fibroblastos obtidas a partir de biópsias de pele de doentes com deficiência em LCHAD e o seu proteoma foi caracterizado e comparado com amostras obtidas de indivíduos saudáveis. Recorrendo a nanoLC-MS/MS 729 proteínas distintas foram identificadas, a grande maioria pertencente aos seguintes clusters funcionais “metabolismo”, “transporte”, “transdução de sinal”, “processos de desenvolvimento e geração de percursores de metabolitos e energia”. Da análise dos resultados obtidos com marcação com iTRAQs identificaram-se 40 proteínas diferentemente expressas entre os dois doentes com défice de LCHAD e os controlos entre elas estão chaperones, protéases, proteínas associadas ao metabolismo e ainda proteínas associadas ao stress oxidativo. Em geral, este estudo permitiu a obtenção de uma perspetiva global da plasticidade do proteoma mitocondrial perante a deficiência em LCHAD e evidenciou as vias moleculares envolvidas na sua patogénese.

Bladder cancer is one of the most common cancers in humans and its incidence has been increasing during the past years. Seventy percent of newly diagnosed bladder cancers are classified as non-muscle-invasive bladder cancer (NMIBC) and are often associated with high rates of recurrence that require lifelong surveillance. Bacillus Calmette-Guérin (BCG) immunotherapy is the treatment of choice of this disease. However, at the moment there are no biomarkers to predict BCG therapeutics outcome. It is now recognized that malignant transformations are often accompanied by a dysregulation at the O-glycosylation level with an overexpression of short chair O-glycans. Still, little is known regarding their expression in bladder tumors. Taking into account these considerations, this work begins by characterizing (Tn, STn, T, ST, S6T and S3T) antigens in 29 bladder tumors with different clinicopathological natures, low grade (n=17) and high grade (n=7) NMIBC and MIBC (n=5) by immunohistochemistry. This study has demonstrated that sialylated species predominate over neutral antigens (Tn and T). S6T had broader expression (approximately 90% of the tumors) being prevalent among low grade cases. In contrast, S3T expression was more restricted (48%) and more associated with high-grade. It was also observed that STn is characteristic of high grade and invasive tumors (71 and 80% respectively) that currently constitute the primary concern in bladder cancer management. In this context, it was determined the predictive value of STn in BCG immunotherapy outcome in a retrospective series of 94 high-risk tumors. This showed that positivity for this antigen was associated with a better response to treatment (p = 0.024). Moreover it Highlighted the trend towards an increased survival. The incorporation of the antigen S6T, which has the STn domain, into this model increased the overall response (p = 0.001) and survival (p = 0.001). Thus, important information was collected that may guide future studies in the understanding of tumor behaviour, definition of high-risk populations and therapeutics.