Mesenchymal stem cells enhance tumorigenic properties of human glioblastoma through independent cell-cell communication mechanisms.

Mesenchymal stem cells (MSC) display tumor tropism and have been addressed as vehicles for delivery of anti-cancer agents. As cellular components of the tumor microenvironment, MSC also influence tumor progression. However, the contribution of MSC in brain cancer is not well understood since either oncogenic or tumor suppressor effects have been reported for these cells. Here, MSC were found capable of stimulating human Glioblastoma (GBM) cell proliferation through a paracrine effect mediated by TGFB1. Moreover, when in direct cell-cell contact with GBM cells, MSC elicited an increased proliferative and invasive tumor cell behavior under 3D conditions, as well as accelerated tumor development in nude mice, independently of paracrine TGFB1. A secretome profiling of MSC-GBM co-cultures identified 126 differentially expressed proteins and 10 proteins exclusively detected under direct cell-cell contact conditions. Most of these proteins are exosome cargos and are involved in cell motility and tissue development. These results indicate a dynamic interaction between MSC and GBM cells, favoring aggressive tumor cell traits through alternative and independent mechanisms. Overall, these findings indicate that MSC may exert pro-tumorigenic effects when in close contact with tumor cells, which must be carefully considered when employing MSC in targeted cell therapy protocols against cancer.

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.

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.

Embryonic Stem Cell-Related Protein L1TD1 Is Required for Cell Viability, Neurosphere Formation, and Chemoresistance in Medulloblastoma.

Misexpression of stem cell-related genes may occur in some cancer cells, influencing patient's prognosis. This is the case of medulloblastoma, a common and clinically challenging malignant tumor of the central nervous system, where expression of the pluripotency factor, OCT4, is correlated with poor survival. A downstream target of OCT4, L1TD1 (LINE-1 type transposase domain-containing protein 1 family member), encodes a novel embryonic stem cell (ESC)-related protein involved in pluripotency and self-renewal of ESCs. L1TD1 is still poorly characterized and its expression pattern and function in cancer cells are virtually unknown. Although normally restricted to non-neoplastic undifferentiated cells and germ cells, we found that high L1TD1 expression also occurs in medulloblastoma cells, reaching levels similar to those found in ESCs, and is correlated with poor prognosis. Conversely to what is reported during normal cell differentiation, when differentiated cells remain healthy, despite L1TD1 downregulation, depletion of L1TD1 protein levels by targeted gene silencing significantly reduced medulloblastoma cell viability, inhibiting cell proliferation and inducing apoptosis. More strikingly, L1TD1 depletion downregulated expression of the neural stem cell markers, CD133 and Nestin, inhibited neurosphere generation capability, and sensitized medulloblastoma cells to temozolomide and cisplatin, two chemotherapeutic agents of clinical relevance in medulloblastoma treatment. Our findings provide insights about the contribution of pluripotency-related genes to a more aggressive tumor phenotype through their involvement in the acquisition of stem-like properties by cancer cells and point out L1TD1 as a potential therapeutic target in malignant brain tumors.

Influência da adequação postural em cadeira de rodas na função respiratória de pacientes com distrofia muscular de Duchenne / Influence of wheelchair positioning aids on the respiratory function of patients with Duchenne muscular dystrophy

O objetivo deste estudo foi avaliar a influência da adequação postural em cadeira de rodas na função respiratória de pacientes com distrofia muscular de Duchenne (DMD). Participaram 12 pacientes com diagnóstico de DMD e que possuíam cadeira de rodas adaptada com idade variando de 10 a 22 anos. Cada indivíduo foi avaliado na própria cadeira de rodas e em uma cadeira de rodas padrão, ou seja, sem reclinação ou tilt. As cadeiras dos participantes possuíam adaptações no encosto e no assento, confeccionados de acordo com as especificidades de cada paciente. A avaliação consistiu em mensurar o volume minuto (VM), volume corrente (VC), capacidade vital forçada (CVF), pressões inspiratória (PImax) e expiratória (PEmax) máximas e pico de fluxo expiratório (PFE). Para análise dos dados, foi utilizado o teste t pareado, adotando-se o nível de significância de 0,05. As adaptações resultaram em melhores valores estatisticamente significativos de todos os parâmetros respiratórios: VM (8.963,3 e 10.762,5 mL/min; p=0,028), VC (319,1 e 433,6 mL; p=0,005), CVF (1.476,3 e 1.850 mL; p=0,005), PImax (-41,2 e -51,2 cmH2O; p=0,022), PEmax (29,6 e 36,7 cmH2O; p=0,004) e PFE (162,1 e 185 L/min; p=0,018). Nossos resultados sugerem que a adequação postural em cadeira de rodas influenciou positivamente a função respiratória de pacientes com DMD.

The purpose of this study was to determine the influence of wheelchair positioning aids on the respiratory function of patients with Duchenne muscular dystrophy (DMD). Twelve non-ambulatory DMD patients, between 10 to 22 years of age, were evaluated. They were assessed in their adapted wheelchairs and in a standard wheelchair without tilt or reclining. The wheelchairs of the participants possessed adaptations in the backrest and the seat, made according to the specifics of each patient. Minute volume (MV), tidal volume (TV), forced vital capacity (FVC), maximum inspiratory (MIP) and expiratory pressures (MEP) and peak expiratory flow (PEF) were measured. For data analysis we used the paired t-test adopting the significance level of 0.05. The positioning aids resulted in statistically significant better values of all respiratory parameters: MV (8,963.3 and 10,762.5 mL/min; p=0.028), TV (319.1 and 433.6 mL; p=0.005), FVC (1,476.3 and 1,850 mL; p=0.005), MIP (-41.2 and -51.2 cmH2O; p=0.022), MEP (29.6 and 36.7 cmH2O; p=0.004) and PEF (162.1 and 185 L/min; p=0.018). These results may suggest that wheelchair positioning aids can positively influence pulmonary function for non-ambulatory DMD patients.

Expression analysis of stem cell-related genes reveal OCT4 as a predictor of poor clinical outcome in medulloblastoma.

Aberrant expression of stem cell-related genes in tumors may confer more primitive and aggressive traits affecting clinical outcome. Here, we investigated expression and prognostic value of the neural stem cell marker CD133, as well as of the pluripotency genes LIN28 and OCT4 in 37 samples of pediatric medulloblastoma, the most common and challenging type of embryonal tumor. While most medulloblastoma samples expressed CD133 and LIN28, OCT4 expression was found to be more sporadic, with detectable levels occurring in 48% of tumors. Expression levels of OCT4, but not CD133 or LIN28, were significantly correlated with shorter survival (P ≤ 0.0001). Median survival time of patients with tumors hyperexpressing OCT4 and tumors displaying low/undetectable OCT4 expression were 6 and 153 months, respectively. More importantly, when patients were clinically stratified according to their risk of tumor recurrence, positive OCT4 expression in primary tumor specimens could discriminate patients classified as average risk but which further deceased within 5 years of diagnosis (median survival time of 28 months), a poor clinical outcome typical of high risk patients. Our findings reveal a previously unknown prognostic value for OCT4 expression status in medulloblastoma, which might be used as a further indicator of poor survival and aid postoperative treatment selection, with a particular potential benefit for clinically average risk patients.

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.

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.