Cancer surveillance series [corrected]: brain and other central nervous system cancers: recent trends in incidence and mortality

The role of glioma stem cells in chemotherapy resistance and glioblastoma multiforme recurrence

Glioma stem cells (GSCs) constitute a slow-dividing, small population within a heterogeneous glioblastoma. They are able to self-renew, recapitulate a whole tumor, and differentiate into other specific glioblastoma multiforme (GBM) subpopulations. Therefore, they have been held responsible for malignant relapse after primary standard therapy and the poor prognosis of recurrent GBM. The failure of current therapies to eliminate specific GSC subpopulations has been considered a major factor contributing to the inevitable recurrence in GBM patients after treatment. Here, we discuss the molecular mechanisms of chemoresistance of GSCs and the reasons why complete eradication of GSCs is so difficult to achieve. We will also describe the targeted therapies currently available for GSCs and possible mechanisms to overcome such chemoresistance and avoid therapeutic relapse.

[Mnesic disorders caused by left temporal gliomas]

Episodic memory disorders are frequent in patients with temporal lesion. Verbal or visuo-spatial memory disorders depend on the location and the lateralization of the lesion. These disorders are well described in temporal epilepsy but rarely in population with cerebral tumor and especially not specifically focus on temporal glioma. The purpose of this study was to describe neuropsychological examination in patient with temporal glioma in the database of the regional memory centre of Besançon. Four patients were identified (all right-handed and with a left temporal glioma). Verbal episodic memory impairment and auditory-verbal short-term memory impairment were observed. One patient had also visual memory disorders. Therefore, further investigations showed an associated Alzheimer's disease. This finding modified the clinical management of this patient. Extensive neuropsychological assessment should be systematic initially to seek an associated pathology, especially in elderly patients, if the cognitive profile is unusual, during the follow-up to better understand cognitive evolution and the effect of therapies on cognition.

Measuring the optical characteristics of medulloblastoma with optical coherence tomography

Medulloblastoma is the most common malignant pediatric brain tumor. Standard treatment consists of surgical resection, followed by radiation and high-dose chemotherapy. Despite these efforts, recurrence is common, leading to reduced patient survival. Even with successful treatment, there are often severe long-term neurologic impacts on the developing nervous system. We present two quantitative techniques that use a high-resolution optical imaging modality: optical coherence tomography (OCT) to measure refractive index, and the optical attenuation coefficient. To the best of our knowledge, this study is the first to demonstrate OCT analysis of medulloblastoma. Refractive index and optical attenuation coefficient were able to differentiate between normal brain tissue and medulloblastoma in mouse models. More specifically, optical attenuation coefficient imaging of normal cerebellum displayed layers of grey matter and white matter, which were indistinguishable in the structural OCT image. The morphology of the tumor was distinct in the optical attenuation coefficient imaging. These inherent properties may be useful during neurosurgical intervention to better delineate tumor boundaries and minimize resection of normal tissue.

Glioblastoma specific antigens, GD2 and CD90, are not involved in cancer stemness

Glioblastoma multiforme (GBM) is the most malignant World Health Organization grade IV brain tumor. GBM patients have a poor prognosis because of its resistance to standard therapies, such as chemotherapy and radiation. Since stem-like cells have been associated with the treatment resistance of GBM, novel therapies targeting the cancer stem cell (CSC) population is critically required. However, GBM CSCs share molecular and functional characteristics with normal neural stem cells (NSCs). To elucidate differential therapeutic targets of GBM CSCs, we compared surface markers of GBM CSCs with adult human NSCs and found that GD2 and CD90 were specifically overexpressed in GBM CSCs. We further tested whether the GBM CSC specific markers are associated with the cancer stemness using primarily cultured patient-derived GBM cells. However, results consistently indicated that GBM cells with or without GD2 and CD90 had similar in vitro sphere formation capacity, a functional characteristics of CSCs. Therefore, GD2 and CD90, GBM specific surface markers, might not be used as specific therapeutic targets for GBM CSCs, although they could have other clinical utilities.

Modulation of A1 and A2B adenosine receptor activity: a new strategy to sensitise glioblastoma stem cells to chemotherapy

Therapies that target the signal transduction and biological characteristics of cancer stem cells (CSCs) are innovative strategies that are used in combination with conventional chemotherapy and radiotherapy to effectively reduce the recurrence and significantly improve the treatment of glioblastoma multiforme (GBM). The two main strategies that are currently being exploited to eradicate CSCs are (a) chemotherapeutic regimens that specifically drive CSCs toward cell death and (b) those that promote the differentiation of CSCs, thereby depleting the tumour reservoir. Extracellular purines, particularly adenosine triphosphate, have been implicated in the regulation of CSC formation, but currently, no data on the role of adenosine and its receptors in the biological processes of CSCs are available. In this study, we investigated the role of adenosine receptor (AR) subtypes in the survival and differentiation of CSCs isolated from human GBM cells. Stimulation of A₁AR and A_2BAR had a prominent anti-proliferative/pro-apoptotic effect on the CSCs. Notably, an A₁AR agonist also promoted the differentiation of CSCs toward a glial phenotype. The differential effects of the two AR agonists on the survival and/or differentiation of CSCs may be ascribed to their distinct regulation of the kinetics of ERK/AKT phosphorylation and the expression of hypoxia-inducible factors. Most importantly, the AR agonists sensitised CSCs to the genotoxic activity of temozolomide (TMZ) and prolonged its effects, most likely through different mechanisms, are as follows: (i) by A_2BAR potentiating the pro-apoptotic effects of TMZ and (ii) by A₁AR driving cells toward a differentiated phenotype that is more sensitive to TMZ. Taken together, the results of this study suggested that the purinergic system is a novel target for a stem cell-oriented therapy that could reduce the recurrence of GBM and improve the survival rate of GBM patients.

MicroRNA signatures as biomarkers and therapeutic target for CNS embryonal tumors: the pros and the cons

Embryonal tumors of the central nervous system represent a heterogeneous group of childhood cancers with an unknown pathogenesis; diagnosis, on the basis of histological appearance alone, is controversial and patients’ response to therapy is difficult to predict. They encompass medulloblastoma, atypical teratoid/rhabdoid tumors and a group of primitive neuroectodermal tumors. All are aggressive tumors with the tendency to disseminate throughout the central nervous system. The large amount of genomic and molecular data generated over the last 5–10 years encourages optimism that new molecular targets will soon improve outcomes. Recent neurobiological studies have uncovered the key role of microRNAs (miRNAs) in embryonal tumors biology and their potential use as biomarkers is increasingly being recognized and investigated. However the successful use of microRNAs as reliable biomarkers for the detection and management of pediatric brain tumors represents a substantial challenge. This review debates the importance of miRNAs in the biology of central nervous systemembryonal tumors focusing on medulloblastoma and atypical teratoid/rhabdoid tumors and highlights the advantages as well as the limitations of their prospective application as biomarkers and candidates for molecular therapeutic targets.

Adult brain cancer in the U.S. black population: a Surveillance, Epidemiology, and End Results (SEER) analysis of incidence, survival, and trends

Background

Despite much epidemiological research on brain cancer in the United States, the etiology for the various subtypes remains elusive. The black population in the United States currently experiences lower incidence but higher survival rates when compared to other races. Thus, the aim of this study is to analyze the trends in incidence and survival for the 6 most common primary brain tumors in the black population of the United States.

Material/Methods

The Surveillance, Epidemiology, and End Results (SEER) database was utilized in this study to analyze the incidence and survival rates for the 6 most common brain tumor subtypes. Joinpoint 3.5.2 software was used to analyze trends in the incidence of diagnosis from 1973 to 2008. A Kaplan-Meier curve was generated to analyze mean time to death and survival at 60 months.

Results

Joinpoint analysis revealed that per year the incidence of brain cancer in the U.S. black population increased by 0.11 between 1973 and 1989. After this period, a moderate decrease by 0.06 per annum was observed from 1989 to 2008. Lymphoma was the most common primary tumor subtype for black individuals ages 20–34, and glioblastoma was identified as the most common tumor subtype for black individuals in the age groups of 35–49, 50–64, 65–79, and 80+.

Conclusions

This population-based retrospective study of brain cancer in black adults in the United States revealed significant sex and age differences in the incidence of the 6 most common brain tumor subtypes from 1973 to 2008.

Trends in central nervous system tumor incidence relative to other common cancers in adults, adolescents, and children in the United States, 2000 to 2010

BACKGROUND

Time trends in cancer incidence rates (IR) are important to measure the changing burden of cancer on a population over time. The overall IR of cancer in the United States is declining. Although central nervous system tumors (CNST) are rare, they contribute disproportionately to mortality and morbidity. In this analysis, the authors examined trends in the incidence of the most common cancers and CNST between 2000 and 2010.

METHODS

The current analysis used data from the United States Cancer Statistics publication and the Central Brain Tumor Registry of the United States. Age-adjusted IR per 100,000 population with 95% confidence intervals and the annual percent change (APC) with 95% confidence intervals were calculated for selected common cancers and CNST overall and by age, sex, race/ethnicity, selected histologies, and malignancy status.

RESULTS

In adults, there were significant decreases in colon (2000-2010: APC, -3.1), breast (2000-2010: APC, -0.8), lung (2000-2010: APC, -1.1), and prostate (2000-2010: APC, -2.4) cancer as well as malignant CNST (2008-2010: APC, -3.1), but a significant increase was noted in nonmalignant CNST (2004-2010: APC, 2.7). In adolescents, there were significant increases in malignant CNST (2000-2008: APC, 1.0) and nonmalignant CNST (2004-2010: APC, 3.9). In children, there were significant increases in acute lymphocytic leukemia (2000-2010: APC, 1.0), non-Hodgkin lymphoma (2000-2010: APC, 0.6), and malignant CNST (2000-2010: APC, 0.6).

CONCLUSIONS

Surveillance of IR trends is an important way to measure the changing public health and economic burden of cancer. In the current study, there were significant decreases noted in the incidence of adult cancer, whereas adolescent and childhood cancer IR were either stable or increasing.

Brain cancer mortality in an agricultural and a metropolitan region of Rio de Janeiro, Brazil: a population-based, age-period-cohort study, 1996-2010

BACKGROUND

Individuals who live in rural areas are at greater risk for brain cancer, and pesticide exposure may contribute to this increased risk. The aims of this research were to analyze the mortality trends and to estimate the age-period-cohort effects on mortality rates from brain cancer in two regions in Rio de Janeiro, Brazil.

METHODS

This descriptive study examined brain cancer mortality patterns in individuals of both sexes, >19 years of age, who died between 1996 and 2010. They were residents of a rural (Serrana) or a non-rural (Metropolitan) area of Rio de Janeiro, Brazil. We estimated mortality trends using Joinpoint Regression analysis. Age-period-cohort models were estimated using Poisson regression analysis.

RESULTS

The estimated annual percentage change in mortality caused by brain cancer was 3.8% in the Serrana Region (95% confidence interval (CI): 0.8-5.6) and -0.2% (95% CI: -1.2-0.7) in the Metropolitan Region. The results indicated that the relative risk was higher in the rural region for the more recent birth cohorts (1954 and later). Compared with the reference birth cohort (1945-49, Serrana Region), the relative risk was four times higher for individuals born between 1985 and 1989.

CONCLUSIONS

The results of this study indicate that there is an increasing trend in brain cancer mortality rates in the rural Serrana Region in Brazil. A cohort effect occurred in the birth cohorts born in this rural area after 1954. At the ecological level, different environmental factors, especially the use of pesticides, may explain regional disparities in the mortality patterns from brain cancers.

Significance and therapeutic value of miRNAs in embryonal neural tumors

Embryonal tumors of the nervous system are the leading cause of childhood cancer-related morbidity and mortality. Medulloblastoma, supratentorial primitive neuroectodermal tumors, atypical teratoid/rhabdoid tumor and neuroblastoma account for more than 20% of childhood malignancies and typify the current neural embryonal tumor model in pediatric oncology. Mechanisms driving the formation of these tumors point towards impaired differentiation of neuronal and neuron-associated cells during the development of the nervous system as an important factor. The importance of microRNAs (miRNAs) for proper embryonic cell function has been confirmed and their aberrant expressions have been linked to tumor development. The role of miRNAs in controlling essential regulators of key pathways implicated in tumor development makes their use in diagnostics a powerful tool to be used for early detection of cancer, risk assessment and prognosis, as well as for the design of innovative therapeutic strategies. In this review we focus on the significance of miRNAs involved in the biology of embryonal neural tumors, delineate their clinical significance and discuss their potential as a novel therapeutic target.

Cyclin D1 gene G870A variants and primary brain tumors

Alterations of cyclin D1, one of the main regulators of the cell cycle, are known to be involved in various cancers. The CCDN1 G870A polymorphism causes production of a truncated variant with a shorter half-life and thus thought to impact the regulatory effect of CCDN1. The aim of the present study was to contribute to existing results to help to determine the prognostic value of this specific gene variant and evaluate the role of CCDN1 G870A polymorphism in brain cancer susceptibility. A Turkish study group including 99 patients with primary brain tumors and 155 healthy controls were examined. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism analysis. The CCDN1 genotype frequencies in meningioma, glioma and control cases were not significantly different (p>0.05). No significant association was detected according to clinical parameters or tumor characteristics; however, a higher frequency of AG genotype was recorded within patients with astrocytic or oligoastrocytic tumors. A significant association between AG genotype and gliobilastoma multiforme (GBM) was recorded within the patients with glial tumors (p value=0.048 OR: 1.87 CI% 1.010-3.463). According to tumor characteristics, no statistically significant difference was detected within astrocytic, oligoasltrocytic tumors and oligodentrioglias. However, patients with astrocytic astrocytic or oligoastrocytic tumors showed a higher frequency of AG genotype (50%) when compared to those with oligodendrioglial tumors (27.3%). Our results indicate a possible relation between GBM formation and CCDN1 genotype.

Delivery of hypoxia and glioma dual-specific suicide gene using dexamethasone conjugated polyethylenimine for glioblastoma-specific gene therapy

Gene therapy has been considered a promising approach for glioblastoma therapy. To avoid side effects and increase the specificity of gene expression, gene expression should be tightly regulated. In this study, glioma and hypoxia dual-specific plasmids (pEpo-NI2-SV-Luc and pEpo-NI2-SV-HSVtk) were developed by combining the erythropoietin (Epo) enhancer and nestin intron 2 (NI2). In the in vitro studies, pEpo-NI2-SV-Luc showed higher gene expression under hypoxia than normoxia in a glioblastoma-specific manner. The MTT and caspase assays demonstrated that pEpo-NI2-SV-HSVtk specifically induced caspase activity and cell death in hypoxic glioblastoma cells. For in vivo evaluation, subcutaneous and intracranial glioblastoma models were established. Dexamethasone-conjugated-polyethylenimine (PEI-Dexa) was used as a gene carrier, since PEI-Dexa efficiently delivers plasmid to glioblastoma cells and also has an antitumor effect due to the effect of dexamethasone. In the in vivo study in the subcutaneous and intracranial glioblastoma models, the tumor size was reduced more effectively in the pEpo-NI2-SV-HSVtk group than in the control and pSV-HSVtk groups. In addition, higher levels of HSVtk gene expression and TUNEL-positive cells were observed in the pEpo-NI2-SV-HSVtk group compared with the control and pSV-HSVtk groups, suggesting that pEpo-NI2-SV-HSVtk increased the therapeutic efficacy in hypoxic glioblastoma. Therefore, pEpo-NI2-SV-HSVtk/PEI-Dexa complex may be useful for glioblastoma-specific gene therapy.

Role of Akt in human malignant glioma: from oncogenesis to tumor aggressiveness

Gathering evidence has revealed that Akt signaling pathway plays an important role in glioma progression and aggressiveness. Among Akt kinases the most studied, Akt1, has been involved in many cellular processes that are in favor of cell malignancy. More recently, the actions of the two other isoforms, Akt2 and Akt3 have emerged in glioma. After a description of Akt pathway activation, we will explore the role of each isoform in malignant glioma that strengthens the current preclinical and clinical studies evaluating the impact of Akt pathway targeting in glioblastomas.

A 16-gene signature distinguishes anaplastic astrocytoma from glioblastoma

Anaplastic astrocytoma (AA; Grade III) and glioblastoma (GBM; Grade IV) are diffusely infiltrating tumors and are called malignant astrocytomas. The treatment regimen and prognosis are distinctly different between anaplastic astrocytoma and glioblastoma patients. Although histopathology based current grading system is well accepted and largely reproducible, intratumoral histologic variations often lead to difficulties in classification of malignant astrocytoma samples. In order to obtain a more robust molecular classifier, we analysed RT-qPCR expression data of 175 differentially regulated genes across astrocytoma using Prediction Analysis of Microarrays (PAM) and found the most discriminatory 16-gene expression signature for the classification of anaplastic astrocytoma and glioblastoma. The 16-gene signature obtained in the training set was validated in the test set with diagnostic accuracy of 89%. Additionally, validation of the 16-gene signature in multiple independent cohorts revealed that the signature predicted anaplastic astrocytoma and glioblastoma samples with accuracy rates of 99%, 88%, and 92% in TCGA, GSE1993 and GSE4422 datasets, respectively. The protein-protein interaction network and pathway analysis suggested that the 16-genes of the signature identified epithelial-mesenchymal transition (EMT) pathway as the most differentially regulated pathway in glioblastoma compared to anaplastic astrocytoma. In addition to identifying 16 gene classification signature, we also demonstrated that genes involved in epithelial-mesenchymal transition may play an important role in distinguishing glioblastoma from anaplastic astrocytoma.

Targeting cancer stem cells for treatment of glioblastoma multiforme

Cancer stem cells (CSCs) in glioblastoma multiforme (GBM) are radioresistant and chemoresistant, which eventually results in tumor recurrence. Targeting CSCs for treatment is the most crucial issue. There are five methods for targeting the CSCs of GBM. One is to develop a new chemotherapeutic agent specific to CSCs. A second is to use a radiosensitizer to enhance the radiotherapy effect on CSCs. A third is to use immune cells to attack the CSCs. In a fourth method, an agent is used to promote CSCs to differentiate into normal cells. Finally, ongoing gene therapy may be helpful. New therapeutic agents for targeting a signal pathway, such as epidermal growth factor (EGF) and vascular epidermal growth factor (VEGF) or protein kinase inhibitors, have been used for GBM but for CSCs the effects still require further evaluation. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as cyclooxygenase-2 (Cox-2) inhibitors have proven to be effective for increasing radiation sensitivity of CSCs in culture. Autologous dendritic cells (DCs) are one of the promising immunotherapeutic agents in clinical trials and may provide another innovative method for eradication of CSCs. Bone-morphogenetic protein 4 (BMP4) is an agent used to induce CSCs to differentiate into normal glial cells. Research on gene therapy by viral vector is also being carried out in clinical trials. Targeting CSCs by eliminating the GBM tumor may provide an innovative way to reduce tumor recurrence by providing a synergistic effect with conventional treatment. The combination of conventional surgery, chemotherapy, and radiotherapy with stem cell-orientated therapy may provide a new promising treatment for reducing GBM recurrence and improving the survival rate.

Relative survival of patients with non-malignant central nervous system tumours: a descriptive study by the Austrian Brain Tumour Registry

BACKGROUND

Unlike malignant primary central nervous system (CNS) tumours outcome data on non-malignant CNS tumours are scarce. For patients diagnosed from 1996 to 2002 5-year relative survival of only 85.0% has been reported. We investigated this rate in a contemporary patient cohort to update information on survival.

METHODS

We followed a cohort of 3983 cases within the Austrian Brain Tumour Registry. All patients were newly diagnosed from 2005 to 2010 with a histologically confirmed non-malignant CNS tumour. Vital status, cause of death, and population life tables were obtained by 31 December 2011 to calculate relative survival.

RESULTS

Overall 5-year relative survival was 96.1% (95% CI 95.1-97.1%), being significantly lower in tumours of borderline (90.2%, 87.2-92.7%) than benign behaviour (97.4%, 96.3-98.3%). Benign tumour survival ranged from 86.8 for neurofibroma to 99.7% for Schwannoma; for borderline tumours survival rates varied from 83.2 for haemangiopericytoma to 98.4% for myxopapillary ependymoma. Cause of death was directly attributed to the CNS tumour in 39.6%, followed by other cancer (20.4%) and cardiovascular disease (15.8%).

CONCLUSION

The overall excess mortality in patients with non-malignant CNS tumours is 5.5%, indicating a significant improvement in survival over the last decade. Still, the remaining adverse impact on survival underpins the importance of systematic registration of these tumours.

Dendritic cell-based immunotherapy for malignant gliomas

Despite dramatic advances in surgical techniques, imaging and adjuvant radiotherapy or chemotherapy, the prognosis for patients with malignant glial tumors remains dismal. Based on the current knowledge regarding immune responses in the healthy CNS and glioma-bearing hosts, this review discusses dendritic cell-based immunotherapeutic approaches for malignant gliomas and the relevance of recent clinical trials and their outcomes. It is now recognized that the CNS is not an immunologically tolerated site and clearance of arising glioma cells is a routine physiologic function of the normal, noncompromised immune system. To escape from immune surveillance, however, clinically apparent gliomas develop complex mechanisms that suppress tumoricidal immune responses. Although the use of dendritic cells for the treatment of glioma patients may be the most appropriate approach, an effective treatment paradigm for these tumors may eventually require the use of several types of treatment. Additionally, given the heterogeneity of this disease process and an immune-refractory tumor cell population, the series use of rational multiple modalities that target disparate tumor characteristics may be the most effective therapeutic strategy to treat malignant gliomas.

Advances in strategies to improve drug delivery to brain tumors

Brain tumors remain a significant health problem. Advances in the biology of the blood-brain barrier are improving the ability of researchers to target therapeutic peptides, small molecules and other drugs to brain tumors. Simple methods to improve blood-brain barrier penetration include chemical modification, glycosylation and pegylation. Drug-delivery vehicles, such as nanoparticles and liposomes, are also under study. Targeting vectors include natural ligands (e.g., epidermal growth factor) or monoclonal antibodies to receptors (e.g., transferrin or insulin). Other vector-mediated delivery approaches involve the conjugation of a therapeutic peptide or protein with a targeting molecule that can induce transcytosis across blood-brain barrier endothelial cells. The most commonly used vectors are peptidomimetic antibodies to endothelial receptors, such as the transferrin and insulin receptors.

Decreased expression of microRNA-206 correlates with poor clinical outcome in patients with malignant astrocytomas

MicroRNA-206 (miR-206) has been proved to function as a tumor suppressor in several types of human malignant cancers. More recently, it has been demonstrated that the ectopic expression of miR-206 significantly inhibited the proliferation and promoted apoptosis at the early stages in glioma cell U343. In order to investigate the clinical significance of miR-206 expression in human astrocytoma, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was used to characterize the expression patterns of miR-206 in 108 astrocytoma and 20 normal brain tissues. As the results, the expression levels of miR-206 in astrocytoma tissues were significantly lower than those in normal brain tissues (P < 0.001). Additionally, the decreased expression of miR-206 in astrocytoma was significantly associated with advanced pathological grade (P = 0.008), low Karnofsky performance score (KPS, P = 0.02), and large tumor size (P = 0.01). Moreover, Kaplan-Meier survival and Cox regression analyses showed that low miR-206 expression (P < 0.001) and advanced pathological grade (P = 0.02) were independent factors predicting poor prognosis for astrocytomas. In conclusion, this is the first report of the differential expression of miR-206 in human astrocytoma tissues. MiR-206 could be a valuable marker of astrocytoma progression and low miR-206 expression is associated with poor overall survival in patients with malignant astrocytomas.

Are pediatric brain tumors on the rise in the USA? Significant incidence and survival findings from the SEER database analysis

INTRODUCTION

Central nervous system tumors are the second most common form of cancer in children between the ages of 1 and 19 years. We aimed to provide the most recent data on the incidence and survival of these tumors in the USA and to assess the literature.

METHODS

Frequency, rates, and survival sessions were calculated using the November 2008 submission for the US Surveillance Epidemiology and End Results Program. Data were collected and analyzed for children and adolescents aged 1 to 19 years with primary brain tumors.

RESULTS

We found that the incidence rate of all pediatric brain tumors has been on a gradual but steady increase from 1973 to 2008 (p < 0.001). The average annual increase was 1.37 %. Our survival analysis of the individual tumors revealed that the 5-year overall survival for children diagnosed between 1974 and 1978 with medulloblastoma was 43.7 %. However, this increased to 62.8 % for children diagnosed between 1999 and 2003. A similar survival trend was also observed when all the other pediatric brain cancer histologies were collectively analyzed (p < 0.001).

CONCLUSIONS

From our study, we can conclude that contrary to previous reports indicating a plateau in the incidence rates of pediatric brain tumors since the mid-1980s, there has been an increase from 1973 to 2008. Potential causes include environmental carcinogens, but more research is needed to investigate the factors behind this sustained rise in incidence over the years.

Combination therapy targeting integrins reduces glioblastoma tumor growth through antiangiogenic and direct antitumor activity and leads to activation of the pro-proliferative prolactin pathway

Background

Tumors may develop resistance to specific angiogenic inhibitors via activation of alternative pathways. Therefore, multiple angiogenic pathways should be targeted to achieve significant angiogenic blockade. In this study we investigated the effects of a combined application of the angiogenic inhibitors endostatin and tumstatin in a model of human glioblastoma multiforme.

Results

Inhibitors released by stably transfected porcine aortic endothelial cells (PAE) showed anti-angiogenic activity in proliferation and wound-healing assays with endothelial cells (EC). Interestingly, combination of endostatin and tumstatin (ES + Tum) also reduced proliferation of glioma cells and additionally induced morphological changes and apoptosis in vitro. Microencapsulated PAE-cells producing these inhibitors were applied for local therapy in a subcutaneous glioblastoma model. When endostatin or tumstatin were applied separately, in vivo tumor growth was inhibited by 58% and 50%, respectively. Combined application of ES + Tum, in comparison, resulted in a significantly more pronounced inhibition of tumor growth (83%). cDNA microarrays of tumors treated with ES + Tum revealed an up-regulation of prolactin receptor (PRLR). ES + Tum-induced up-regulation of PRLR in glioma cells was also found in in vitro. Moreover, exogenous PRLR overexpression in vitro led to up-regulation of its ligand prolactin and increased proliferation suggesting a functional autocrine growth loop in these cells.

Conclusion

Our data indicate that integrin-targeting factors endostatin and tumstatin act additively by inhibiting glioblastoma growth via reduction of vessel density but also directly by affecting proliferation and viability of tumor cells. Treatment with the ES + Tum-combination activates the PRLR pro-proliferative pathway in glioblastoma. Future work will show whether the prolactin signaling pathway represents an additional target to improve therapeutic strategies in this entity.

Trends in childhood brain tumor incidence, 1973-2009

In the mid-1980s, there was a rise in incidence rates of childhood brain tumors (CBT) in the United States that appeared to stabilize at a higher rate in the early 1990 s. An updated analysis of the pattern of CBT over the past 2 decades, with commentary on whether the elevated incidence rate has continued, is past due. We used Surveillance, Epidemiology and End Results (SEER) data to examine trends in incidence of CBT from 1973 through 2009. We examined age-adjusted incidence rates (AAIRs) and secular trends for all malignant brain tumors combined (SEER classification) by histologic tumor type and anatomic site. The incidence of CBT remained stable from 1987 to 2009 [annual percent change (APC) = 0.10; 95 % confidence intervals (CI) -0.39 to 0.61] with an AAIR for all CBT of 3.32 (95 % CI 3.22-3.42). The stability of rates in these two decades contrast the change that occurred in the mid-1980s (1983-1986), when the incidence of CBT increased by 53 % (APC = 14.06; 95 % CI 4.05-25.0). From 1983 to 1986, statistically significant rate increases were observed for pilocytic astrocytoma, PNET/medulloblastoma, and mixed glioma. Further, the rate of increase in pilocytic astrocytoma was similar to the rate of decrease for astrocytomas NOS from 1981 to 2009, suggesting a change from a more general to more specific classification. After the increase in rates in the mid-1980s, rates of CBT over the past two decades have stabilized. Changes in incidence rates of subtypes of tumors over this time period reflect changes both in classification of CBT and in diagnostic techniques.

G-quadruplexes as potential therapeutic targets for embryonal tumors

Embryonal tumors include a heterogeneous group of highly malignant neoplasms that primarily affect infants and children and are characterized by a high rate of mortality and treatment-related morbidity, hence improved therapies are clearly needed. G-quadruplexes are special secondary structures adopted in guanine (G)-rich DNA sequences that are often present in biologically important regions, e.g. at the end of telomeres and in the regulatory regions of oncogenes such as MYC. Owing to the significant roles that both telomeres and MYC play in cancer cell biology, G-quadruplexes have been viewed as emerging therapeutic targets in oncology and as tools for novel anticancer drug design. Several compounds that target these structures have shown promising anticancer activity in tumor xenograft models and some of them have entered Phase II clinical trials. In this review we examine approaches to DNA targeted cancer therapy, summarize the recent developments of G-quadruplex ligands as anticancer drugs and speculate on the future direction of such structures as a potential novel therapeutic strategy for embryonal tumors of the nervous system.

Is cancer risk still reduced if you give up smoking in later life?

SUMMARY This report summarizes the experimental and epidemiological evidence examining the ability of smoking cessation to influence cancer risk reduction in later life. Available evidence suggests that smoking cessation even in later years can significantly reduce mortality and yield risk reductions for many cancers including lung, oral, head and neck, and stomach cancer, among others. More research is necessary to accurately quantify the degree of cancer risk reduction for particular age groups and to calculate the minimum time of cessation necessary to produce a significant benefit for the patient. Smoking cessation is the only approach that has been shown to effectively reduce the risk of many cancers on a mass scale. Considering this, we recommend that healthcare providers communicate these benefits to patients at every opportunity and reinforce the notion that it is never too late to quit smoking.

Intranasal delivery of mesenchymal stem cells significantly extends survival of irradiated mice with experimental brain tumors

Treatment options of glioblastoma multiforme are limited due to the blood-brain barrier (BBB). In this study, we investigated the utility of intranasal (IN) delivery as a means of transporting stem cell-based antiglioma therapeutics. We hypothesized that mesenchymal stem cells (MSCs) delivered via nasal application could impart therapeutic efficacy when expressing TNF-related apoptosis-inducing ligand (TRAIL) in a model of human glioma. ¹¹¹In-oxine, histology and magnetic resonance imaging (MRI) were utilized to track MSCs within the brain and associated tumor. We demonstrate that MSCs can penetrate the brain from nasal cavity and infiltrate intracranial glioma xenografts in a mouse model. Furthermore, irradiation of tumor-bearing mice tripled the penetration of (¹¹¹In)-oxine-labeled MSCs in the brain with a fivefold increase in cerebellum. Significant increase in CXCL12 expression was observed in irradiated xenograft tissue, implicating a CXCL12-dependent mechanism of MSCs migration towards irradiated glioma xenografts. Finally, MSCs expressing TRAIL improved the median survival of irradiated mice bearing intracranial U87 glioma xenografts in comparison with nonirradiated and irradiated control mice. Cumulatively, our data suggest that IN delivery of stem cell-based therapeutics is a feasible and highly efficacious treatment modality, allowing for repeated application of modified stem cells to target malignant glioma.

The Evangelismos hospital central nervous system tumor registry: Analysis of 1414 cases (1998-2009)

Background:

The Evangelismos Hospital central nervous system (CNS) Tumor Registry represents the current effort of the Departments of Neurosurgery and Pathology to collect data for primary and metastatic CNS tumor patients. In the present study, 12-year hospital data (1998-2009) were reviewed and analyzed.

Methods:

Patients that underwent surgery for CNS tumors for the first time were identified. Histologically confirmed tumor rates by age and gender were compared. Time trends in annual rates for specific tumor types were investigated. In-hospital mortality rates and length of hospital stay were analyzed by age and gender and their putative variations across the study period investigated.

Results:

A total of 1414 patients (age 15-89 years) were identified. The most frequently encountered histologies were gliomas and meningiomas, accounting for, respectively, 32.8% and 29.1% of the total sample. A greater proportion of meningiomas was found in women; the proportion of glioblastomas and metastatic tumors, as well as of mixed gliomas, were greater in men. Increased rates of glioblastoma and meningioma with advancing age at diagnosis were also apparent. There were no significant variations in time trends for specific tumor types. In-hospital mortality was significantly higher for older patients (≥70 years). An increase in the length of hospital stay was apparent between the first and middle third of the study period.

Conclusions:

Analysis of tumor rates in relation to age at diagnosis and gender showed significant bias in accordance with salient literature. Available data indicated no significant variations in time trends for specific tumor types across the study period, while an adverse effect of advanced age on in-hospital mortality was shown. The present findings can guide the formulation of future treatment programs and preventive strategies and provide the basis for further intra- and/or interdepartmental research.

Brazilin inhibits growth and induces apoptosis in human glioblastoma cells

Brazilin, isolated from the methanol extract of the heart wood of Caesalpinia sappan, sensitizes cancer cells to apoptosis. Glioblastoma multiforme (GBM), which accounts for most cases of central nervous system malignancy, has a very poor prognosis and lacks effective therapeutic interventions. We, therefore, investigated the effects of different concentrations of and different periods of exposure to brazilin on cell proliferation and apoptosis in the glioma U87 cell line. Cell proliferation was investigated by MTT assays and growth curve analysis, apoptosis was assessed by FACS analysis and western blot studies. Brazilin showed dose-dependent inhibition of cell proliferation and induction of apoptosis in glioma cells. It also increased the ratio of cleaved poly-(ADP)-ribose polymerase and decreased the expression of caspase-3 and caspase-7.

Acute and fractionated irradiation differentially modulate glioma stem cell division kinetics

Glioblastoma multiforme (GBM) is one of the most aggressive human malignancies with a poor patient prognosis. Ionizing radiation either alone or adjuvant after surgery is part of standard treatment for GBM but remains primarily noncurative. The mechanisms underlying tumor radioresistance are manifold and, in part, accredited to a special subpopulation of tumorigenic cells. The so-called glioma stem cells (GSC) are bestowed with the exclusive ability to self-renew and repopulate the tumor and have been reported to be less sensitive to radiation-induced damage through preferential activation of DNA damage checkpoint responses and increased capacity for DNA damage repair. During each fraction of radiation, non-stem cancer cells (CC) die and GSCs become enriched and potentially increase in number, which may lead to accelerated repopulation. We propose a cellular Potts model that simulates the kinetics of GSCs and CCs in glioblastoma growth and radiation response. We parameterize and validate this model with experimental data of the U87-MG human glioblastoma cell line. Simulations are conducted to estimate GSC symmetric and asymmetric division rates and explore potential mechanisms for increased GSC fractions after irradiation. Simulations reveal that in addition to their higher radioresistance, a shift from asymmetric to symmetric division or a fast cycle of GSCs following fractionated radiation treatment is required to yield results that match experimental observations. We hypothesize a constitutive activation of stem cell division kinetics signaling pathways during fractionated treatment, which contributes to the frequently observed accelerated repopulation after therapeutic irradiation.

The role of semaphorins and their receptors in gliomas

Gliomas are the most common tumor in the central nervous system. High-grade glioblastomas are characterized by their high invasiveness and resistance to radiotherapy, leading to high recurrence rate and short median survival despite radical surgical resection. Characterizations of gliomas at molecular level have revealed aberrations of various growth factor receptors, receptor tyrosine kinases, and tumor suppressor genes that lead to deregulation of multiple signaling pathways, thereby contributing to abnormal proliferation, invasion, and resistance to apoptosis in cancer cells. Recently, accumulating evidence points to the emerging role of axon guidance molecules in glioma progression. Notably, many signaling events harnessed by guidance molecules to regulate cell migration and axon navigation during development are also found to be involved in the modulation of deregulated pathways in gliomas. This paper focused on the signalings triggered by the guidance molecule semaphorins and their receptors plexins and neuropilins, and how their crosstalk with oncogenic pathways in gliomas might modulate cancer progression. The emerging role of semaphorins and plexins as tumor suppressors or oncogenes is also discussed.

Diagnostic segregation of human brain tumours using Fourier-transform infrared and/or Raman spectroscopy coupled with discriminant analysis

The most common initial treatment received by patients with a brain tumour is surgical removal of the growth. Precise histopathological diagnosis of brain tumours is to some extent subjective. Furthermore, currently available diagnostic imaging techniques to delineate the excision border during cytoreductive surgery lack the required spatial precision to aid surgeons. We set out to determine whether infrared (IR) and/or Raman spectroscopy combined with multivariate analysis could be applied to discriminate between normal brain tissue and different tumour types (meningioma, glioma and brain metastasis) based on the unique spectral "fingerprints" of their biochemical composition. Formalin-fixed paraffin-embedded tissue blocks of normal brain and different brain tumours were de-waxed, mounted on low-E slides and desiccated before being analyzed using attenuated total reflection Fourier-transform IR (ATR-FTIR) and Raman spectroscopy. ATR-FTIR spectroscopy showed a clear segregation between normal and different tumour subtypes. Discrimination of tumour classes was also apparent with Raman spectroscopy. Further analysis of spectral data revealed changes in brain biochemical structure associated with different tumours. Decreased tentatively-assigned lipid-to-protein ratio was associated with increased tumour progression. Alteration in cholesterol esters-to-phenylalanine ratio was evident in grade IV glioma and metastatic tumours. The current study indicates that IR and/or Raman spectroscopy have the potential to provide a novel diagnostic approach in the accurate diagnosis of brain tumours and have potential for application in intra-operative diagnosis.

Targeting glioma stem cells by functional inhibition of a prosurvival oncomiR-138 in malignant gliomas

Malignant gliomas are the most aggressive forms of brain tumors, associated with high rates of morbidity and mortality. Recurrence and tumorigenesis are attributed to a subpopulation of tumor-initiating glioma stem cells (GSCs) that are intrinsically resistant to therapy. Initiation and progression of gliomas have been linked to alterations in microRNA expression. Here, we report the identification of microRNA-138 (miR-138) as a molecular signature of GSCs and demonstrate a vital role for miR-138 in promoting growth and survival of bona fide tumor-initiating cells with self-renewal potential. Sequence-specific functional inhibition of miR-138 prevents tumorsphere formation in vitro and impedes tumorigenesis in vivo. We delineate the components of the miR-138 regulatory network by loss-of-function analysis to identify specific regulators of apoptosis. Finally, the higher expression of miR-138 in GSCs compared to non-neoplastic tissue and association with tumor recurrence and survival highlights the clinical significance of miR-138 as a prognostic biomarker and a therapeutic target for treatment of malignant gliomas.

Phosphoproteome of human glioblastoma initiating cells reveals novel signaling regulators encoded by the transcriptome

Background

Glioblastoma is one of the most aggressive tumors with poor prognosis. Although various studies have been performed so far, there are not effective treatments for patients with glioblastoma.

Methodology/Principal Findings

In order to systematically elucidate the aberrant signaling machinery activated in this malignant brain tumor, we investigated phosphoproteome dynamics of glioblastoma initiating cells using high-resolution nanoflow LC-MS/MS system in combination with SILAC technology. Through phosphopeptide enrichment by titanium dioxide beads, a total of 6,073 phosphopeptides from 2,282 phosphorylated proteins were identified based on the two peptide fragmentation methodologies of collision induced dissociation and higher-energy C-trap dissociation. The SILAC-based quantification described 516 up-regulated and 275 down-regulated phosphorylation sites upon epidermal growth factor stimulation, including the comprehensive status of the phosphorylation sites on stem cell markers such as nestin. Very intriguingly, our in-depth phosphoproteome analysis led to identification of novel phosphorylated molecules encoded by the undefined sequence regions of the human transcripts, one of which was regulated upon external stimulation in human glioblastoma initiating cells.

Conclusions/Significance

Our result unveils an expanded diversity of the regulatory phosphoproteome defined by the human transcriptome.

Nanotechnology applications for glioblastoma

Glioblastoma remains one of the most difficult cancers to treat and represents the most common primary malignancy of the brain. Although conventional treatments have found modest success in reducing the initial tumor burden, infiltrating cancer cells beyond the main mass are responsible for tumor recurrence and ultimate patient demise. Targeting residual infiltrating cancer cells requires the development of new treatment strategies. The emerging field of cancer nanotechnology holds promise in the use of multifunctional nanoparticles for imaging and targeted therapy of glioblastoma. This article examines the current state of nanotechnology in the treatment of glioblastoma and directions of further study.

Glioblastoma cancer stem-like cells: implications for pathogenesis and treatment

Glioblastoma remains one of the deadliest forms of cancer. Infiltrating cancer cells in the surrounding brain prevent complete resection, and tumor cell resistance to chemoradiation results in the poor prognosis of the glioblastoma (GBM) patient. Much research has been devoted over the years to the pathogenesis and treatment of GBM. The tumor stem cell hypothesis, which was initially described in hematopoietic cell malignancies, may explain the resistance of these tumors to conventional therapies. In this model, a certain subset of tumor cells, with characteristics similar to normal stem cells, is capable of producing the variety of cell types, which constitute the bulk of a tumor. As these tumor cells have properties distinct from those constituting the bulk of the tumor, a different approach may be required to eradicate these residual cells within the brain. Here we outline the history behind the theory of GBM cancer stem-like cells, as they are now referred to. We will also discuss the implications of their existence on commonly held beliefs about GBM pathogenesis and how they might influence future treatment strategies.

uPAR and cathepsin B inhibition enhanced radiation-induced apoptosis in gliomainitiating cells

Glioblastomas present as diffuse tumors with invasion into normal brain tissue and frequently recur or progress after radiation as focal masses because of glioma-initiating cells. The role of the urokinase-type plasminogen activator receptor (uPAR) and cathepsin B in stem-like phenotype has been extensively studied in several solid tumors. In the present study, we demonstrated that selection of glioma-initiating cells using CD133 expression leads to a specific enrichment of CD133(+) cells in both U87 and 4910 cells. In addition, CD133(+) cells exhibited a considerable amount of other stem cell markers, such as Nestin and Sox-2. Radiation treatment significantly enhanced uPAR and cathepsin B levels in glioma-initiating cells. To downregulate radiation-induced uPAR and cathepsin B expression, we used a bicistronic shRNA construct that simultaneously targets both uPAR and cathepsin B (pCU). Downregulation of uPAR and cathepsin B using pCU decreased radiation-enhanced uPAR and cathepsin B levels and caused DNA damage-induced apoptosis in glioma cell lines and glioma-initiating cells. The most striking finding of this study is that knockdown of uPAR and cathepsin B inhibited ongoing transcription by suppressing BrUTP incorporation at γH2AX foci. In addition, uPAR and cathepsin B gene silencing inversely regulated survivin and H2AX expression in both glioma cells and glioma-initiating cells. Pretreatment with pCU reduced radiation-enhanced expression of uPAR, cathepsin B, and survivin and enhanced DNA damage in pre-established glioma in nude mice. Taken together, our in vitro and in vivo findings suggest that uPAR and cathepsin B inhibition might serve as an adjunct to radiation therapy to target glioma-initiating cells and, therefore, for the treatment of glioma.

Identifying family members who are likely to perceive benefits from providing care to a person with a primary malignant brain tumor

PURPOSE/OBJECTIVES

To identify changes in positive aspects of care (PAC) from the time of diagnosis to four months following the diagnosis in family caregivers of care recipients with primary malignant brain tumors.

DESIGN

Longitudinal.

SETTING

Dyads were recruited from neurosurgery clinics in Pittsburgh, PA, at the time of care recipients' diagnosis with a primary malignant brain tumor. A second data collection took place four months following the diagnosis.

SAMPLE

89 caregiver and care recipient dyads.

METHODS

Paired t tests were used to examine change in PAC, univariate analyses were used to determine predictors of PAC at four months, Mann-Whitney U tests and t tests were used to examine associations between categorical predictor variables and PAC at four months, and univariate linear regressions were used to examine associations between continuous predictors and PAC at four months.

MAIN RESEARCH VARIABLES

The impact of sociodemographic factors, caregiver-perceived social support, mastery, neuroticism, and marital satisfaction on PAC.

FINDINGS

Caregivers' PAC scores during the first four months following diagnosis appeared to remain stable over time. Significant differences were found between the care recipient reasoning domain group at diagnosis and PAC score. Care recipients who scored below average were associated with caregivers with higher PAC scores. Caregiver PAC at four months following diagnosis was significantly predicted by care recipient reasoning and caregiver social support.

CONCLUSIONS

PAC scores appear to remain stable over time, although levels of PAC may be related to care recipients' level of functioning. Future research should focus on the development of interventions for caregivers who report low levels of PAC at the time of diagnosis in an attempt to help these individuals identify PAC in their caregiving situation.

IMPLICATIONS FOR NURSING

Findings have clinical and research implications. Clinicians may be able to better identify caregivers who are at risk for negative outcomes by understanding the risks faced by caregivers of patients with milder symptoms in addition to those caring for more profoundly affected care recipients.

Gene expression by simian virus 40 large T antigen-induced medulloblastomas in mice

Signaling pathways known to have components with mutations in human medulloblastoma include sonic hedgehog, Wnt/beta-catenin and insulin-like growth factor. Microarray analysis was applied to examine the gene expression changes in medulloblastomas of pTet-on/pTRE-SV40Tag transgenic mice. Altogether, 14 112 genes were detectable, including 152 genes with significantly different expression levels. These genes were associated with immunity, the cell cycle, signal transduction, cytoskeleton and metabolism. To further confirm the microarray data, real-time polymerase chain reactions were used to examine the expression changes of genes related to sonic hedgehog, Wnt/beta-catenin and insulin-like growth factor signal pathways. Immunohistochemistry detected insulin receptor substrate-1 in the nuclei of brain tumor tissue cells from pTet-on/pTRE-SV40Tag transgenic mice, suggesting that SV40 large T antigen may activate the insulin-like growth factor signal pathway to promote tumorigenesis.

Knockdown of checkpoint kinase 1 is associated with the increased radiosensitivity of glioblastoma stem-like cells

Glioblastoma multiforme is an aggressive brain tumor with a poor prognosis. The glioblastoma stem-like cells (GSCs) represent a rare fraction of human glioblastoma cells with the capacity for multi-lineage differentiation, self-renewal and exact recapitulation of the original tumor. Interestingly, GSCs are more radioresistant compared with other tumor cells. In addition, the remarkable radioresistance of GSCs has been known to promote radiotherapy failure and therefore is associated with a significantly higher risk of a local tumor recurrence. Moreover, the hyperactive cell cycle checkpoint kinase (Chk) 1 and 2 play a pivotal role in the DNA damage response including radiation and chemical therapy. Based on aforementioned, we hypothesized that knockdown of Chk1 or Chk2 might confer radiosensitivity on GSCs and thereby increases the efficiency of radiotherapy. In this study, we knocked down the expression of Chk1 or Chk2 in human GSCs using lentivirus-delivered short hairpin RNA (shRNA) to examine its effect on the radiosensitivity. After radiation, the apoptosis rate and the cell cycle of GSCs were measured with Flow Cytometry. Compared with control GSCs (apoptosis, 7.82 ± 0.38%; G2/M arrest, 60.20 ± 1.28%), Chk1 knockdown in GSCs increased the apoptosis rate (37.87 ± 0.32%) and decreased the degree of the G2/M arrest (22.37 ± 2.01%). In contrast, the radiosensitivity was not enhanced by Chk2 knockdown in GSCs. These results suggest that depletion of Chk1 may improve the radio-sensitivity of GSCs via inducing cell apoptosis. In summary, the therapy targeting Chk1 gene in the GSCs may be a novel way to treat glioblastoma.