Advances in the management of pediatric central nervous system tumors

Early Cognitive and Adaptive Functioning of Clinically Referred Infants and Toddlers with Cancer

Many children with cancer are diagnosed during infancy and toddlerhood (< 3 years of age), potentially resulting in disrupted and/or missed developmental opportunities. Our objective was to describe the functioning of infants and toddlers with cancer who were clinically referred for evaluation at a hospital-based psychology clinic. Data from 29 very young children with cancer (M_age = 23.62 ± 6.6 months; 55.2% male) who completed clinically referred assessments from 2010 to 2015 were abstracted. Children were 11.3 months post-diagnosis (SD = 7.77, range 1-29 months) with just over half off-therapy at the time of assessment (55.2%). Overall, developmental functioning was significantly below expectations [t(22) = - 8.99, p < .001]. Adaptive functioning [t(25) = - 6.41, p < .001] was also significantly below expectations. Infants and toddlers with cancer appear to be at significant risk for weaknesses in early cognitive and adaptive functioning. The margin of deficits found in this study warrant the need for further investigation and consideration of this young population to ensure optimal functional development.

Transitional care in pediatric neurosurgical patients

The relatively young specialty field of pediatric neurosurgery addresses a number of surgical diseases that, while first encountered in children, may involve long-term post-operative sequelae that persist into adulthood. These diagnoses present a challenge for care providers as patients transition from pediatric to adult age groups. Brain tumors, shunted hydrocephalus, and myelomeningocele are three of the most common examples of this interesting category. The provision of coordinated transitional care to affected pediatric neurosurgical patients is made all the more difficult by the common comorbidity of developmental delay, affecting not only personal and social growth but also the character and composition of the care team. This article seeks to provide a background for some of the common pediatric neurosurgical diseases requiring a transitional care framework for survivors entering young adulthood, a summary of the adult surgical care challenges faced by these patients, and a rationale for different approaches to optimize care.

Nuclear condensation and cell cycle arrest induced by telomerase siRNA in neuroblastoma cells

Neuroblastoma is a type of malignant extracranial tumor that occurs in children. Advanced neuroblastoma, and tumors with MYCN amplification in particular, have poor prognoses. Therefore, it is important to find an effective cure for this disease. Small interfering RNA (siRNA) disrupts gene function by specifically binding to target mRNA. In this study, we used siRNA against telomerase to treat neuroblastoma, to evaluate any anti-proliferative effect on these cells. We evaluated cell viability by WST-1 assay on neuroblastoma cells treated with or without telomerase siRNA. Nuclear condensation, an indicator for apoptotic cells, was determined by DAPI labeling following siRNA treatment. The effectiveness of telomerase siRNA on altering the neuroblastoma cell cycle was detected by flow cytometry. Our results indicated that telomerase siRNA reduces the viability of neuroblastoma cells and increases the percentage of cells in the cell cycle's sub-G1 phase. We found that telomerase siRNA increases the percentage of condensed DNA in neuroblastoma cells. In conclusion, using siRNA against telomerase could be further developed as a therapy for the treatment of neuroblastoma.

Trans-differentiation of neural stem cells: a therapeutic mechanism against the radiation induced brain damage

Radiation therapy is an indispensable therapeutic modality for various brain diseases. Though endogenous neural stem cells (NSCs) would provide regenerative potential, many patients nevertheless suffer from radiation-induced brain damage. Accordingly, we tested beneficial effects of exogenous NSC supplementation using in vivo mouse models that received whole brain irradiation. Systemic supplementation of primarily cultured mouse fetal NSCs inhibited radiation-induced brain atrophy and thereby preserved brain functions such as short-term memory. Transplanted NSCs migrated to the irradiated brain and differentiated into neurons, astrocytes, or oligodendrocytes. In addition, neurotrophic factors such as NGF were significantly increased in the brain by NSCs, indicating that both paracrine and replacement effects could be the therapeutic mechanisms of NSCs. Interestingly, NSCs also differentiated into brain endothelial cells, which was accompanied by the restoration the cerebral blood flow that was reduced from the irradiation. Inhibition of the VEGF signaling reduced the migration and trans-differentiation of NSCs. Therefore, trans-differentiation of NSCs into brain endothelial cells by the VEGF signaling and the consequential restoration of the cerebral blood flow would also be one of the therapeutic mechanisms of NSCs. In summary, our data demonstrate that exogenous NSC supplementation could prevent radiation-induced functional loss of the brain. Therefore, successful combination of brain radiation therapy and NSC supplementation would provide a highly promising therapeutic option for patients with various brain diseases.

Why does Jack, and not Jill, break his crown? Sex disparity in brain tumors

It is often reported that brain tumors occur more frequently in males, and that males suffer a worse outcome from brain tumors than females. If correct, these observations suggest that sex plays a fundamental role in brain tumor biology. The following review of the literature regarding primary and metastatic brain tumors, reveals that brain tumors do occur more frequently in males compared to females regardless of age, tumor histology, or region of the world. Sexually dimorphic mechanisms that might control tumor cell biology, as well as immune and brain microenvironmental responses to cancer, are explored as the basis for this sex disparity. Elucidating the mechanisms by which sex chromosomes and sex hormones impact on brain tumorigenesis and progression will advance our understanding of basic cancer biology and is likely to be essential for optimizing the care of brain tumor patients.

Short-term neurological outcome of children after surgery for brain tumors: incidence and characteristics in a pediatric intensive care unit

PURPOSE

The main treatment for majority of pediatric brain tumors relies on surgery. In postoperative period, patients require monitoring in a pediatric intensive care unit (PICU). In this study, we analyzed the incidence of postoperative neurological complications and the outcome of neurological impairment in individual patients.

PATIENTS AND METHODS

Our retrospective single-center study concerned all patients who were admitted to the PICU of the University Hospital of Angers between 2002 and 2008, after brain tumor resection. Population, perioperative data, and outcome through the stay in PICU have been analyzed.

RESULTS

We reported 117 neurosurgical procedures. Majority of children (85.3%) were affected by neurological deficit before surgery: cranial nerve palsy and cerebellar syndrome were the most frequent impairment. In the first 2 days, neurological symptoms improved for 27 patients (23.7%), especially in children with preoperative cerebellar syndrome, convulsions, or endocrine disorders. Mean length of stay in PICU was correlated with the severity of neurological impairment (p = 0.006). Five children presented a transient mutism after surgery for infratentorial tumors (n = 5/54, 9.2%). Eight spontaneous cerebral spinal fluid leaks occurred precociously after surgery, and neurological infections complicated half of them. Neurological infections occurred in 12 patients (ten meningitis, one ventriculitis, and one brain abscess). One patient died after surgery.

CONCLUSIONS

All these complications and their risk factors have to be systematically searched for in order to decrease postoperative morbidity of brain tumors in children. They justify neurosurgeons and anesthesiologists specialized in these pathologies.

Pediatric brain tumor cancer stem cells: cell cycle dynamics, DNA repair, and etoposide extrusion

Reliable model systems are needed to elucidate the role cancer stem cells (CSCs) play in pediatric brain tumor drug resistance. The majority of studies to date have focused on clinically distinct adult tumors and restricted tumor types. Here, the CSC component of 7 newly established primary pediatric cell lines (2 ependymomas, 2 medulloblastomas, 2 gliomas, and a CNS primitive neuroectodermal tumor) was thoroughly characterized. Comparison of DNA copy number with the original corresponding tumor demonstrated that genomic changes present in the original tumor, typical of that particular tumor type, were retained in culture. In each case, the CSC component was approximately 3–4-fold enriched in neurosphere culture compared with monolayer culture, and a higher capacity for multilineage differentiation was observed for neurosphere-derived cells. DNA content profiles of neurosphere-derived cells expressing the CSC marker nestin demonstrated the presence of cells in all phases of the cell cycle, indicating that not all CSCs are quiescent. Furthermore, neurosphere-derived cells demonstrated an increased resistance to etoposide compared with monolayer-derived cells, having lower initial DNA damage, potentially due to a combination of increased drug extrusion by ATP-binding cassette multidrug transporters and enhanced rates of DNA repair. Finally, orthotopic xenograft models reflecting the tumor of origin were established from these cell lines. In summary, these cell lines and the approach taken provide a robust model system that can be used to develop our understanding of the biology of CSCs in pediatric brain tumors and other cancer types and to preclinically test therapeutic agents.

New approaches to pharmacotherapy of tumors of the nervous system during childhood and adolescence

Tumors of the nervous system are among the most common and most chemoresistant neoplasms of childhood and adolescence. Malignant tumors of the brain collectively account for 21% of all cancers and 24% of all cancer-related deaths in this age group. Neuroblastoma, a peripheral nervous system tumor, is the most common extracranial solid tumor of childhood, and 65% of children with this tumor have only a 10 or 15% chance of living 5 years beyond the time of initial diagnosis. Novel pharmacological approaches to nervous system tumors are urgently needed. This review presents the role of and current challenges to pharmacotherapy of malignant tumors of the nervous system during childhood and adolescence and discusses novel approaches aimed at overcoming these challenges.