Genetically modified ZIKA virus as a microRNA-sensitive oncolytic virus against central nervous system tumors.

Here we introduce a first-in-class microRNA-sensitive oncolytic Zika virus (ZIKV) for virotherapy application against central nervous system (CNS) tumors. The described methodology produced two synthetic modified ZIKV strains that are safe in normal cells, including neural stem cells, while preserving brain tropism and oncolytic effects in tumor cells. The microRNA-sensitive ZIKV introduces genetic modifications in two different virus sites: first, in the established 3'UTR region, and secondly, in the ZIKV protein coding sequence, demonstrating for the first time that the miRNA inhibition systems can be functional outside the UTR RNA sites. The total tumor remission in mice bearing human CNS tumors, including metastatic tumor growth, after intraventricular and systemic modified ZIKV administration, confirms the promise of this virotherapy as a novel agent against brain tumors-highly deadly diseases in urgent need of effective advanced therapies.

High OCT4A levels drive tumorigenicity and metastatic potential of medulloblastoma cells.

Medulloblastoma is a highly aggressive pediatric brain tumor, in which sporadic expression of the pluripotency factor OCT4 has been recently correlated with poor patient survival. However the contribution of specific OCT4 isoforms to tumor aggressiveness is still poorly understood. Here, we report that medulloblastoma cells stably overexpressing the OCT4A isoform displayed enhanced clonogenic, tumorsphere generation, and invasion capabilities. Moreover, in an orthotopic metastatic model of medulloblastoma, OCT4A overexpressing cells generated more developed, aggressive and infiltrative tumors, with tumor-bearing mice attaining advanced metastatic disease and shorter survival rates. Pro-oncogenic OCT4A effects were expression-level dependent and accompanied by distinct chromosomal aberrations. OCT4A overexpression in medulloblastoma cells also induced a marked differential expression of non-coding RNAs, including poorly characterized long non-coding RNAs and small nucleolar RNAs. Altogether, our findings support the relevance of pluripotency-related factors in the aggravation of medulloblastoma traits classically associated with poor clinical outcome, and underscore the prognostic and therapeutic value of OCT4A in this challenging type of pediatric brain cancer.

Establishment of a novel human medulloblastoma cell line characterized by highly aggressive stem-like cells.

Medulloblastoma is a highly aggressive brain tumor and one of the leading causes of morbidity and mortality related to childhood cancer. These tumors display differential ability to metastasize and respond to treatment, which reflects their high degree of heterogeneity at the genetic and molecular levels. Such heterogeneity of medulloblastoma brings an additional challenge to the understanding of its physiopathology and impacts the development of new therapeutic strategies. This translational effort has been the focus of most pre-clinical studies which invariably employ experimental models using human tumor cell lines. Nonetheless, compared to other cancers, relatively few cell lines of human medulloblastoma are available in central repositories, partly due to the rarity of these tumors and to the intrinsic difficulties in establishing continuous cell lines from pediatric brain tumors. Here, we report the establishment of a new human medulloblastoma cell line which, in comparison with the commonly used and well-established cell line Daoy, is characterized by enhanced proliferation and invasion capabilities, stem cell properties, increased chemoresistance, tumorigenicity in an orthotopic metastatic model, replication of original medulloblastoma behavior in vivo, strong chromosome structural instability and deregulation of genes involved in neural development. These features are advantageous for designing biologically relevant experimental models in clinically oriented studies, making this novel cell line, named USP-13-Med, instrumental for the study of medulloblastoma biology and treatment.

Aberrant signaling pathways in medulloblastomas: a stem cell connection.

Medulloblastoma is a highly malignant primary tumor of the central nervous system. It represents the most frequent type of solid tumor and the leading cause of death related to cancer in early childhood. Current treatment includes surgery, chemotherapy and radiotherapy which may lead to severe cognitive impairment and secondary brain tumors. New perspectives for therapeutic development have emerged with the identification of stem-like cells displaying high tumorigenic potential and increased radio- and chemo-resistance in gliomas. Under the cancer stem cell hypothesis, transformation of neural stem cells and/or granular neuron progenitors of the cerebellum are though to be involved in medulloblastoma development. Dissecting the genetic and molecular alterations associated with this process should significantly impact both basic and applied cancer research. Based on cumulative evidences in the fields of genetics and molecular biology of medulloblastomas, we discuss the possible involvement of developmental signaling pathways as critical biochemical switches determining normal neurogenesis or tumorigenesis. From the clinical viewpoint, modulation of signaling pathways such as TGFß, regulating neural stem cell proliferation and tumor development, might be attempted as an alternative strategy for future drug development aiming at more efficient therapies and improved clinical outcome of patients with pediatric brain cancers.

Aberrant signaling pathways in medulloblastomas: a stem cell connection / Vias de sinalização aberrantes no meduloblastoma: uma conexão com célula-tronco

Medulloblastoma is a highly malignant primary tumor of the central nervous system. It represents the most frequent type of solid tumor and the leading cause of death related to cancer in early childhood. Current treatment includes surgery, chemotherapy and radiotherapy which may lead to severe cognitive impairment and secondary brain tumors. New perspectives for therapeutic development have emerged with the identification of stem-like cells displaying high tumorigenic potential and increased radio- and chemo-resistance in gliomas. Under the cancer stem cell hypothesis, transformation of neural stem cells and/or granular neuron progenitors of the cerebellum are though to be involved in medulloblastoma development. Dissecting the genetic and molecular alterations associated with this process should significantly impact both basic and applied cancer research. Based on cumulative evidences in the fields of genetics and molecular biology of medulloblastomas, we discuss the possible involvement of developmental signaling pathways as critical biochemical switches determining normal neurogenesis or tumorigenesis. From the clinical viewpoint, modulation of signaling pathways such as TGFβ, regulating neural stem cell proliferation and tumor development, might be attempted as an alternative strategy for future drug development aiming at more efficient therapies and improved clinical outcome of patients with pediatric brain cancers.

Meduloblastoma é um tumor maligno do sistema nervoso central (SNC). Na infância, representa o tumor sólido mais frequente e a principal causa de morte relacionada ao câncer. Tratamentos atuais incluem cirurgia, quimioterapia e radioterapia, que podem trazer prejuízos cognitivos e desenvolvimento de tumores secundários. Novas perspectivas terapêuticas surgem com a identificação de células-tronco em gliomas, as quais apresentam alto potencial tumorigênico e maior resistência à radioterapia e quimioterapia. A hipótese das células-tronco tumorais sugere que a transformação de células-tronco e/ou progenitores neurais do cerebelo está envolvida no desenvolvimento do meduloblastoma. Portanto, analisar alterações genéticas e moleculares envolvidas nesse processo é de grande importância na pesquisa básica e aplicada ao câncer. Nesse sentido, discutimos o possível envolvimento de vias de sinalização bioquímica críticas a ambos os processos de neurogênese normal ou tumorigênese, com base em evidências atuais na área de genética e biologia molecular dos meduloblastomas. Do ponto de vista clínico, a modulação de vias de sinalização como a do TGFβ, regulando proliferação de célula-tronco neural e desenvolvimento tumoral, pode ser uma estratégia alternativa para o desenvolvimento de novos medicamentos objetivando-se terapias mais eficientes e melhora do prognóstico dos pacientes pediátricos com câncer de SNC.

Células-tronco e progenitores no sistema nervoso central: aspectos básicos e relevância clínica / Stem and progenitor cells from the central nervous system: basic aspects and clinical relevance

Distúrbios no processo de neurogênese têm sido correlacionados com diferentes patologias, como doenças neurodegenerativas, epilepsia, síndrome de Down e depressão. Nessa revisão, discute se o envolvimento de células-tronco neurais e neuroprogenitores ao longo do desenvolvimento e maturação do sistema nervoso. São destacadas a relevância dessas células ao funcionamento do sistema nervoso central nos contextos fisiológico e patológico, bem como novas estratégias terapêuticas baseadas na modulação da neurogênese pós-natal.

Estratégias para neurorrestauração em modelos experimentais de doença de Parkinson / Strategies for neuronal recovery in experimental models of Parkinson’s disease

Modelos experimentais animais têm sido fundamentais para o avançodo conhecimento a respeito da fisiopatologia da doença de Parkinson,bem como ao desenvolvimento de novas abordagens terapêuticasbaseadas em processos intrínsecos à sua patogênese. Entre as novasestratégias terapêuticas atualmente em experimentação, destacam-seas baseadas em processos neurorrestauradores pelo transplante comcélulas-tronco neurais e/ou neuroprogenitores fetais. Embora estudospré-clínicos demonstrem efeitos positivos com relação à reposiçãode neurônios dopaminérgicos, preservação de circuitária neuronal e amenização de sintomas clínicos, principalmente os motores, questõesfundamentais ainda persistem e devem ser pesquisadas antes que aterapia celular se consolide como alternativa ao tratamento da doençade Parkinson. Além da reposição de neurônios dopaminérgicos,a manipulação do microambiente celular e a mobilização deneuroprogenitores endógenos surgem como alternativas a seremexploradas. Em relação à segurança desses procedimentos, estudosde longo prazo em modelos animais são importantes e devem serrealizados para acessar eventuais distúrbios motores, cognitivos ecomportamentais, bem como a possibilidade de desenvolvimentode tumores.