Targeting the epigenome of cancer stem cells in pediatric nervous system tumors.

Medulloblastoma, neuroblastoma, and pediatric glioma account for almost 30% of all cases of pediatric cancers. Recent evidence indicates that pediatric nervous system tumors originate from stem or progenitor cells and present a subpopulation of cells with highly tumorigenic and stem cell-like features. These cancer stem cells play a role in initiation, progression, and resistance to treatment of pediatric nervous system tumors. Histone modification, DNA methylation, chromatin remodeling, and microRNA regulation display a range of regulatory activities involved in cancer origin and progression, and cellular identity, especially those associated with stem cell features, such as self-renewal and pluripotent differentiation potential. Here, we review the contribution of different epigenetic mechanisms in pediatric nervous system tumor cancer stem cells. The choice between a differentiated and undifferentiated state can be modulated by alterations in the epigenome through the regulation of stemness genes such as CD133, SOX2, and BMI1 and the activation neuronal of differentiation markers, RBFOX3, GFAP, and S100B. Additionally, we highlighted the stage of development of epigenetic drugs and the clinical benefits and efficacy of epigenetic modulators in pediatric nervous system tumors.

Primary cells derived from Tuberous Sclerosis Complex patients show autophagy alteration in the haploinsufficiency state.

Tuberous sclerosis complex (TSC) is an autosomal dominant cancer predisposition disorder caused by heterozygous mutations in TSC1 or TSC2 genes and characterized by mTORC1 hyperactivation. TSC-associated tumors develop after loss of heterozygosity mutations and their treatment involves the use of mTORC1 inhibitors. We aimed to evaluate cellular processes regulated by mTORC1 in TSC cells with different mutations before tumor development. Flow cytometry analyses were performed to evaluate cell viability, cell cycle and autophagy in non-tumor primary TSC cells with different heterozygous mutations and in control cells without TSC mutations, before and after treatment with rapamycin (mTORC1 inhibitor). We did not observe differences in cell viability and cell cycle between the cell groups. However, autophagy was reduced in mutated cells. After rapamycin treatment, mutated cells showed a significant increase in the autophagy process (p=0.039). We did not observe differences between cells with distinct TSC mutations. Our main finding is the alteration of autophagy in non-tumor TSC cells. Previous studies in literature found autophagy alterations in tumor TSC cells or knock-out animal models. We showed that autophagy could be an important mechanism that leads to TSC tumor formation in the haploinsufficiency state. This result could guide future studies in this field.

A Prognostic Methylation-Driven Two-Gene Signature in Medulloblastoma.

Medulloblastoma (MB) is one of the most common pediatric brain tumors and it is estimated that one-third of patients will not achieve long-term survival. Conventional prognostic parameters have limited and unreliable correlations with MB outcome, presenting a major challenge for patients' clinical improvement. Acknowledging this issue, our aim was to build a gene signature and evaluate its potential as a new prognostic model for patients with the disease. In this study, we used six datasets totaling 1679 samples including RNA gene expression and DNA methylation data from primary MB as well as control samples from healthy cerebellum. We identified methylation-driven genes (MDGs) in MB, genes whose expression is correlated with their methylation. We employed LASSO regression, incorporating the MDGs as a parameter to develop the prognostic model. Through this approach, we derived a two-gene signature (GS-2) of candidate prognostic biomarkers for MB (CEMIP and NCBP3). Using a risk score model, we confirmed the GS-2 impact on overall survival (OS) with Kaplan-Meier analysis. We evaluated its robustness and accuracy with receiver operating characteristic curves predicting OS at 1, 3, and 5 years in multiple independent datasets. The GS-2 showed highly significant results as an independent prognostic biomarker compared to traditional MB markers. The methylation-regulated GS-2 risk score model can effectively classify patients with MB into high and low-risk, reinforcing the importance of this epigenetic modification in the disease. Such genes stand out as promising prognostic biomarkers with potential application for MB treatment.

Antitumor Activities and Cellular Changes Induced by TrkB Inhibition in Medulloblastoma.

Neurotrophins are critically involved in regulating normal neural development and plasticity. Brain-derived neurotrophic factor (BDNF), a neurotrophin that acts by binding to the tropomyosin receptor kinase B (TrkB) receptor, has also been implicated in the progression of several types of cancer. However, its role in medulloblastoma (MB), the most common type of malignant brain tumor afflicting children, remains unclear. Here we show that selective TrkB inhibition with the small molecule compound ANA-12 impaired proliferation and viability of human UW228 and D283 MB cells, and slowed the growth of MB tumors xenografted into nude mice. These effects were accompanied by increased apoptosis, reduced extracellular-regulated kinase (ERK) activity, increased expression of signal transducer and activator of transcription 3 (STAT3), and differential modulation of p21 expression dependent on the cell line. In addition, MB cells treated with ANA-12 showed morphological alterations consistent with differentiation, increased levels of the neural differentiation marker ß-III Tubulin (TUBB3), and reduced expression of the stemness marker Nestin. These findings are consistent with the possibility that selective TrkB inhibition can display consistent anticancer effects in MB, possibly by modulating intracellular signaling and gene expression related to tumor progression, apoptosis, and differentiation.

Toll-like Receptors 2, 3, and 4 in Childhood Acute Lymphocytic Leukemia / Receptores do Tipo Toll 2, 3 e 4 em Leucemia Linfocítica Aguda Infanti / Receptores Tipo Toll 2, 3 y 4 en la Leucemia Linfocítica Aguda Infantil

Introduction: Acute lymphocytic leukemia (ALL) is the most common cancer type in children and accounts for 80% of pediatric leukemias. Novel targets are necessary to improve survival rates for refractory and relapsed disease. There is accumulating evidence that Toll-like Receptor (TLR) signaling may be associated with outcomes in cancer however little has been described in leukemias. Objective: Analyze the expression and contribution of TLRs to the development of childhood ALL. Method: To evaluate the effect of specific TLR2, TLR3, and TLR4 agonists on the viability and proliferation of childhood ALL cell lines and to analyzed the mRNA expression of these types of TLR in bone marrow blast cells at diagnosis (D0) and induction (D35) in pediatric ALL patients. Results: Treatment with TLR agonists reduced the cell viability of Jurkat and Sup-B15 cell lines. Cell cycle distribution in Jurkat was altered, reducing polyploid cells and increasing sub-G1 phase. Conclusion: It was observed that the cell viability of the cell lines responded with different sensitivities to the agonists. The polyploidy associated with tumor malignancy was reduced, in addition to the increase in the sub-G1 phase indicating an increase in apoptosis. There were differences in TLR expression at D35 between groups at risk of the disease. Patients with high expression of TLR2 and low expression of TLR4 on D35 demonstrated a worse prognosis

Introdução: A leucemia linfoblástica aguda (LLA) é o tipo de câncer mais comum em crianças e representa 80% das leucemias pediátricas. Novos alvos são necessários para melhorar as taxas de sobrevivência para doença refratária e recidivante. Há evidências acumuladas de que a sinalização de receptores Toll-Like (TLR) pode estar associada a resultados em câncer, embora pouco tenha sido descrito em leucemias. Objetivo: Analisar a expressão e a contribuição dos TLR para o desenvolvimento da LLA infantil. Método: Avaliar o efeito de agonistas específicos de TLR2, TLR3 e TLR4 na viabilidade e proliferação de linhagens celulares de LLA infantil e analisar a expressão do RNAm desses tipos de TLR em células blásticas da medula óssea no diagnóstico (D0) e na indução (D35) em pacientes LLA pediátricos. Resultados: O tratamento com agonistas de TLR reduziu a viabilidade celular das linhagens celulares Jurkat e Sup-B15. A distribuição do ciclo celular em Jurkat foi alterada, reduzindo as células poliploides e aumentando a fase sub-G1. Houve aumento na expressão dos receptores entre D0 e D35 em amostras de pacientes. Conclusão: Observou-se que a viabilidade celular das linhagens celulares respondeu com diferentes sensibilidades aos agonistas. A poliploidia associada à malignidade tumoral foi reduzida, além de o aumento da fase sub-G1 indicar aumento da apoptose. Houve diferenças na expressão de TLR em D35 entre os grupos de risco da doença. Pacientes com alta expressão de TLR2 e baixa expressão de TLR4 no D35 demonstraram pior prognóstico.

Introducción: La leucemia linfocítica aguda (LLA) es el tipo de cáncer más común en los niños y representa el 80 % de las leucemias pediátricas. Se necesitan nuevos objetivos para mejorar las tasas de supervivencia de la enfermedad refractaria y recidivante. Cada vez hay más pruebas de que la señalización del receptor Toll-Like (TLR) puede estar asociada con resultados en el cáncer, aunque se ha descrito poco en las leucemias. Objetivo: Analizar la expresión y la contribución de los TLR al desarrollo de la LLA infantil. Método: Evaluar el efecto de agonistas específicos de TLR2, TLR3 y TLR4 en la viabilidad y proliferación de líneas celulares de LLA infantil y analizar la expresión de ARNm de estos tipos de TLR en células blásticas de médula ósea en el momento del diagnóstico (D0) y la inducción (D35) en pacientes pediátricos con LLA. Resultados: El tratamiento con agonistas de TLR redujo la viabilidad celular de las líneas celulares Jurkat y sup-B15. Se alteró la distribución del ciclo celular en Jurkat, reduciendo las células poliploides y aumentando la fase sub-G1. Hubo un aumento en la expresión de los receptores entre D0 y D35 en muestras de pacientes. Conclusión: Se observó que la viabilidad celular de las líneas celulares respondía con distintas sensibilidades a los agonistas. Se redujo la poliploidía asociada con la malignidad del tumor, además de un aumento de la fase sub-G1 que indica un aumento de la apoptosis. Hubo diferencias en la expresión de TLR en D35 entre los grupos de riesgo de enfermedad. Los pacientes con alta expresión de TLR2 y baja expresión de TLR4 en D35 mostraron peor pronóstico

Olfactory and respiratory lamina propria transplantation after spinal cord transection in rats: effects on functional recovery and axonal regeneration.

Spinal cord injury (SCI) has very poor clinical prospects, resulting in irreversible loss of function below the injury site. Although applied in clinical trials, olfactory ensheathing cells transplantation (OEC) derived from lamina propria (OLP) is still a controversial repair strategy. The present study explored the efficacy of OLP or respiratory lamina propria (RLP) transplantation and the optimum period after SCI for application of this potential therapy. Adult male rats were submitted to spinal cord transection and underwent acute, 2-week or 4-week post-injury transplantation with pieces of OLP (containing OECs) or RLP (without OECs). After grafting, animals with OLP and RLP showed discrete and similar hindlimb motor improvement, with comparable spinal cord tissue sparing and sprouting in the lesion area. Acute transplantation of OLP and RLP seems to foster limited supraspinal axonal regeneration as shown by the presence of neurons stained by retrograde tracing in the brainstem nuclei. A larger number of 5-HT positive fibers were found in the cranial stump of the OLP and RLP groups compared to the lesion and caudal regions. Calcitonin gene-related peptide fibers were present in considerable numbers at the SCI site in both types of transplantation. Our results failed to verify differences between acute, 2-week and 4-week delayed transplantation of OLP and RLP, suggesting that the limited functional and axon reparative effects observed could not be exclusively related to OECs. A greater understanding of the effects of these tissue grafts is necessary to strengthen the rationale for application of this treatment in humans.