Brain and other central nervous system tumors: rates, trends, and epidemiology

Population-based survival data for brain tumors in Korea

Primary brain tumors are relatively uncommon but particularly lethal cancers. Although survival is useful for monitoring the effects of early cancer detection and treatment, there are few population-based estimates of survival for subjects with brain tumors, especially in Asian countries. Using the Korea National Cancer Incidence Database, 4,721 newly diagnosed cases of histologically confirmed malignant primary brain tumors from 1999 to 2004 were analyzed for observed survival. For trend analyses of glioblastomas, we included 2,751 glioblastoma cases diagnosed between 1999 and 2007. We compared survival by age group and histological type by use of the Kaplan-Meier method. For all ages and all brain tumor types in Korea, five-year survival was 37.5 %. For each histological type of brain tumor survival of pediatric and younger adult populations was much better than that of older adults. Five-year survival for glioblastoma, astrocytoma, anaplastic astrocytoma, and oligodendroglioma was 8.9, 51.6, 25.2, and 73.5 %, respectively. Two-year survival for glioblastoma increased from 18.6 % for cases diagnosed in 1999-2001 to 21.3 % for cases diagnosed in 2002-2004 and to 24.7 % for cases diagnosed in 2005-2007. These results may help clinicians and patients to assess long-term prognoses for brain tumors, and the data presented here could serve as master control data set for single-arm clinical trials, especially in Asian populations.

Early recurrence in standard-risk medulloblastoma patients with the common idic(17)(p11.2) rearrangement

Medulloblastoma is diagnosed histologically; treatment depends on staging and age of onset. Whereas clinical factors identify a standard- and a high-risk population, these findings cannot differentiate which standard-risk patients will relapse and die. Outcome is thought to be influenced by tumor subtype and molecular alterations. Poor prognosis has been associated with isochromosome (i)17q in some but not all studies. In most instances, molecular investigations document that i17q is not a true isochromosome but rather an isodicentric chromosome, idic(17)(p11.2), with rearrangement breakpoints mapping within the REPA/REPB region on 17p11.2. This study explores the clinical utility of testing for idic(17)(p11.2) rearrangements using an assay based on fluorescent in situ hybridization (FISH). This test was applied to 58 consecutive standard- and high-risk medulloblastomas with a 5-year minimum of clinical follow-up. The presence of i17q (ie, including cases not involving the common breakpoint), idic(17)(p11.2), and histologic subtype was correlated with clinical outcome. Overall survival (OS) and disease-free survival (DFS) were consistent with literature reports. Fourteen patients (25%) had i17q, with 10 (18%) involving the common isodicentric rearrangement. The presence of i17q was associated with a poor prognosis. OS and DFS were poor in all cases with anaplasia (4), unresectable disease (7), and metastases at presentation (10); however, patients with standard-risk tumors fared better. Of these 44 cases, tumors with idic(17)(p11.2) were associated with significantly worse patient outcomes and shorter mean DFS. FISH detection of idic(17)(p11.2) may be useful for risk stratification in standard-risk patients. The presence of this abnormal chromosome is associated with early recurrence of medulloblastoma.

Long-term follow-up of children treated for high-grade gliomas: children's oncology group L991 final study report

PURPOSE

High-grade gliomas of the CNS are characterized by poor treatment response and prognosis for long-term survival. The Children's Oncology Group (COG) L991 study investigated the neuropsychological, behavioral, and quality of life (QoL) outcomes after treatment on the Children's Cancer Group (CCG) trial for high-grade gliomas (CCG-945).

PATIENTS AND METHODS

Fifty-four patients (29 males, 25 females) with a median age of 8.8 years at diagnosis (range, 0.2 to 19.5 years) were enrolled at 25 institutions in North America, representing 81% of available survivors; median length of follow-up was 15.1 years (range, 9.5 to 19.2 years), and median age at study evaluation was 23.6 years (range, 11.3 to 36 years). Standardized tests of neuropsychological functioning and QoL were performed. Descriptive statistics summarized principal findings, and one-way analysis of variance identified potential predictors of outcomes.

RESULTS

With an average follow-up time of 15 years, survivors demonstrated intellectual functioning within the low-average range. Executive functioning and verbal memory were between the low-average and borderline ranges. In contrast, visual memory and psychomotor processing speed were between the borderline and impaired ranges, respectively. Approximately 75% of patient reported overall QoL within or above normal limits for both physical and psychosocial domains. Nonhemispheric tumor location (midline or cerebellum), female sex, and younger age at treatment emerged as independent risk factors.

CONCLUSION

These results serve as a benchmark for comparison with future pediatric high-grade glioma studies, in addition to identifying at-risk cohorts that warrant further research and proactive interventions to minimize late effects while striving to ensure survival.

Nuclear remodeling as a mechanism for genomic instability in cancer

This chapter focuses on the three-dimensional organization of the nucleus in normal, early genomically unstable, and tumor cells. A cause-consequence relationship is discussed between nuclear alterations and the resulting genomic rearrangements. Examples are presented from studies on conditional Myc deregulation, experimental tumorigenesis in mouse plasmacytoma, nuclear remodeling in Hodgkin's lymphoma, and in adult glioblastoma. A model of nuclear remodeling is proposed for cancer progression in multiple myeloma. Current models of nuclear remodeling are described, including our model of altered nuclear architecture and the onset of genomic instability.

Glioblastoma-derived epidermal growth factor receptor carboxyl-terminal deletion mutants are transforming and are sensitive to EGFR-directed therapies

Genomic alterations of the epidermal growth factor receptor (EGFR) gene play a crucial role in pathogenesis of glioblastoma multiforme (GBM). By systematic analysis of GBM genomic data, we have identified and characterized a novel exon 27 deletion mutation occurring within the EGFR carboxyl-terminus domain (CTD), in addition to identifying additional examples of previously reported deletion mutations in this region. We show that the GBM-derived EGFR CTD deletion mutants are able to induce cellular transformation in vitro and in vivo in the absence of ligand and receptor autophosphorylation. Treatment with the EGFR-targeted monoclonal antibody, cetuximab, or the small molecule EGFR inhibitor, erlotinib, effectively impaired tumorigenicity of oncogenic EGFR CTD deletion mutants. Cetuximab in particular prolonged the survival of intracranially xenografted mice with oncogenic EGFR CTD deletion mutants, compared with untreated control mice. Therefore, we propose that erlotinib and, especially, cetuximab treatment may be a promising therapeutic strategy in GBM patients harboring EGFR CTD deletion mutants.

Impact of therapy on quality of life, neurocognitive function and their correlates in glioblastoma multiforme: a review

The maintenance of quality of life (QoL) in patients with high-grade glioma is an important endpoint during treatment, particularly in those with glioblastoma multiforme (GBM) given its dismal prognosis despite limited advances in standard therapy. It has proven difficult to identify new therapies that extend survival in patients with recurrent GBM, so one of the primary aims of new therapies is to reduce morbidity, restore or preserve neurologic functions, and the capacity to perform daily activities. Apart from temozolomide, cytotoxic chemotherapeutic agents do not appear to significantly impact response or survival, but produce toxicity that is likely to negatively impact QoL. New biological agents, such as bevacizumab, can induce a clinically meaningful proportion of durable responses among patients with recurrent GBM with an acceptable safety profile. Emerging evidence suggests that bevacizumab produces an improvement or preservation of neurocognitive function in GBM patients, suggestive of QoL improvement, in most poor-prognosis patients who would otherwise be expected to show a sudden and rapid deterioration in QoL.

Protective role of 17 β-estradiol on medulloblastoma development in Patched 1 heterozygous mice

Medulloblastoma (MB) is the most common pediatric tumor of the CNS, representing ∼20% of all childhood CNS tumors. Although in recent years many molecular mechanisms that control MB development have been clarified, the effects of biological factors such as sex on this tumor remain to be explained. Epidemiological data, in fact, indicate a significant difference in the incidence of MB between the 2 sexes, with considerably higher susceptibility of males than females. Besides this different susceptibility, female sex is also a significant favorable prognostic factor in MB, with girls having a much better outcome. Despite these literature data, there has been little investigation into estrogen influence on MB development. In our study, we evaluated how hormone deficiency resulting from ovariectomy and hormone replacement influences the development of early and advanced MB stages in Patched1 heterozygous mice, a well-characterized mouse model of radiation-induced MB. Susceptibility to MB development was significantly increased in ovariectomized Ptch1(+/-) females and restored to levels observed in control mice after estrogen replacement. We next investigated the molecular mechanisms by which estrogen might influence tumor progression and show that ERβ, but not ERα, is involved in modulation of MB development by estrogens. Finally, our study shows that a functional interaction between estrogen- and IGF-I-mediated pathways may be responsible for the effects observed.

Incidence of craniopharyngioma in Denmark (n = 189) and estimated world incidence of craniopharyngioma in children and adults

We studied the incidence of craniopharyngioma in Denmark during the period 1985-2004 and estimated worldwide incidence rates (IR) of craniopharyngioma based on a literature review. Craniopharyngioma patients diagnosed during the period 1985-2004 were identified from the Danish National Patient Registry, the Danish Cancer Registry and regional registries. Medical records were reviewed. Danish population data were obtained from Statistics Denmark. European and World population data were obtained from EU and WHO homepages. Prior studies providing data on craniopharyngioma IRs were identified via PubMed and, if appropriate, were included in a weighted analysis estimating overall and children's IRs of craniopharyngioma. IRs are given as new cases per million per year. We identified 189 patients with new verified (162) or probable craniopharyngioma. The overall WHO World-standardised incidence rate was 1.86 (1.60-2.14) for all ages and 2.14 (1.53-2.92) for children (age <15 years). Peak incidence rates were observed in age groups 5-9 and 40-44 years. Fifteen prior studies (including 1,232 craniopharyngioma cases) were identified. Seven and 11 studies, respectively, were eligible for weighted all-ages and childhood population IR analyses, yielding summary IRs of 1.34 (1.24-1.46) (all ages) and 1.44 (1.33-1.56) (children). We have provided a detailed survey of the incidence of craniopharyngioma in Denmark during a recent 20-year period. Overall IR of craniopharyngioma in Denmark was 1.86 (1.60-2.14) as compared to 2.14 (1.53-2.92) among children. Weighted estimates of craniopharyngioma world IRs were 1.34 (1.24-1.46) in all ages and 1.44 (1.33-1.56) among children.

Bone morphogenetic protein-7 is a MYC target with prosurvival functions in childhood medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children. It is known that overexpression and/or amplification of the MYC oncogene is associated with poor clinical outcome, but the molecular mechanisms and the MYC downstream effectors in MB remain still elusive. Besides contributing to elucidate how progression of MB takes place, most importantly, the identification of novel MYC-target genes will suggest novel candidates for targeted therapy in MB. A group of 209 MYC-responsive genes was obtained from a complementary DNA microarray analysis of a MB-derived cell line, following MYC overexpression and silencing. Among the MYC-responsive genes, we identified the members of the bone morphogenetic protein (BMP) signaling pathway, which have a crucial role during the development of the cerebellum. In particular, the gene BMP7 was identified as a direct target of MYC. A positive correlation between MYC and BMP7 expression was documented by analyzing two distinct sets of primary MB samples. Functional studies in vitro using a small-molecule inhibitor of the BMP/SMAD signaling pathway reproduced the effect of the small interfering RNA-mediated silencing of BMP7. Both approaches led to a block of proliferation in a panel of MB cells and to inhibition of SMAD phosphorylation. Altogether, our findings indicate that high MYC levels drive BMP7 overexpression, promoting cell survival in MB cells. This observation suggests the potential relevance of targeting the BMP/SMAD pathway as a novel therapeutic approach for the treatment of childhood MB.

Imaging in primary central nervous system lymphoma

Primary central nervous system (CNS) lymphoma (PCNSL) accounts for approximately 3% of all primary CNS tumors. Congenital or acquired immunodeficiency is the only established risk factor for PCNSL. Rates decreased slightly in the mid-1990s, concordantly with the decreasing rates of AIDS. However, the incidence has been increasing in the elderly immunocompetent population, and this trend seems to be independent of improvements in diagnostic techniques, and of overall trends in the incidence of brain tumors and systemic lymphomas. This study presents our experience with the imaging features of PCNSL. Computed tomography (CT) and magnetic resonance imaging (MRI) findings were reviewed in a series of 38 cases of pathologically proven PCNSL. The incidence rate of PCNSL was higher in men than in women (58% versus 42%). Mean age at presentation was 63 years; 120 lesions were demonstrated in the 38 patients, with a 53% frequency of tumor multiplicity. Both CT and MR mainly showed solitary or multiple well-defined round or oval-shaped mass lesions, typically hyperdense on unenhanced CT scans, iso to hypointense on T2 MR weighted images. These lesions also showed an increased signal intensity on diffusion-weighted images. Virtually all lesions enhanced after intravenous administration of contrastmedium. On (1)H-magnetic resonance spectroscopy ((1)H-MRS) most lesions presented increased Cho/Cr, Cho/NAA and lactate/Cr ratios when compared to normal gray matter. No changes in the imaging presentation have occurred over the past two decades, apart from lesions now being smaller at diagnosis. Our imaging findings are in agreement with the existing literature data and with the reported increasing trend of multifocal tumors. Our epidemiologic results add value to the existing evidence of increasing incidence rates among the immunocompetent elderly population.

Intracranial tumors in Kuwait: a 15-year survey

The dearth of literature on intracranial tumors (ICT) in Kuwait has necessitated this study whose objective is epidemiological. It is based on the records of the Department of Pathology, Al-Sabah Hospital, Kuwait, where virtually all brain biopsies in Kuwait were examined. Between 1995 and 2009, 439 males (53.41%) and 383 females (46.59%) had primary intracranial tumors (PICT). Most (69%) were younger than 50 years, with 16% children and adolescents and 4% elderly (≥70 years); meningioma (28%), pituitary adenoma (19%), glioblastoma (15%), astrocytoma (13%), and medulloblastoma (5%) were the most common. In childhood and adolescence, astrocytoma (35.34%) and medulloblastoma (22.56%) predominated. The mean age-adjusted incidence rate/100,000 was: PICT: 3.02; astrocytic tumors: 0.93; meningioma: 0.96; pituitary adenoma: 0.44; and medulloblastoma: 0.13. All showed a declining trend which was only statistically significant for medulloblastoma (P = 0.007). A modest correlation between the percentage of elderly in the general population and incidence rates was found (r = 0.411). Tumors with significant male preponderance were high-grade astrocytic tumors, silent pituitary adenoma (SA), and nerve sheath tumor. Meningioma had a female to male ratio of 2.24. The peak frequency for functional pituitary adenoma and females was in the age range of 20-29 years, while for SA and males it was 40-49 years. About 5% of ICT were metastatic, with cancers of breast (26%), lung (17%) and gastrointestinal (11%) origin as the most common. In conclusion, the epidemiology of PICT in Kuwait is characterized by low incidence rates and a distinct age distribution.

Human malignant glioma cells expressing functional formylpeptide receptor recruit endothelial progenitor cells for neovascularization

Endothelial progenitor cells (EPCs) are involved in tumor neovascularization with undefined mechanisms. In this study, we explored the role of formylpeptide receptor, a G protein-coupled receptor, expressed by human malignant glioma cells in neovascularization of malignant glioma. EPCs were isolated from human umbilical cord blood and their migratory capability and tubulogenesis induced by the supernatant of U87 glioblastoma (GBM) cell line were examined. We also assessed the recruitment and incorporation of EPCs into orthotopic intracranial tumors formed by implanted U87 GBM cells. The supernatant of control U87 cells induced high levels of migration and tubule-formation in vitro by EPCs. In contrast, the chemotactic and tubule-stimulating activities on EPCs in the supernatant of U87 cells with FPR knocking down by small interference (si) RNA were significantly attenuated. In addition, the number of EPCs recruited and incorporated into intracranial glioma xenografts was significantly higher in tumors formed by control U87 cells than tumors formed by U87 cells containing FPR-siRNA. Our results suggest that expression of functional FPR in glioma cells plays an important role in regulating vasculogenesis by EPCs, which constitute a novel target for anti-angiogenic therapy in gliomas.

Surgical outcome of patients considered to have "inoperable" tumors by specialized pediatric neuro-oncological multidisciplinary teams

PURPOSE

Despite the lack of evidence in literature, it is widely felt that patient outcomes will be improved by adopting a multidisciplinary team (MDT) approach to children with brain tumors. This study focuses on a series of pediatric patients treated surgically despite a MDT recommendation against surgery.

METHODS

A retrospective study was conducted on all pediatric brain and spinal cord tumor patients operated in a single center from 1999 to 2009. Of the 256 surgical patients, 47 patients (18%) had been previously seen by a MDT who had recommended against surgery. Details of preoperative treatment, diagnosis and clinical status, postoperative diagnosis, early and late outcomes, progression-free survival and overall survival, and parental satisfaction were reviewed.

RESULTS

There was a single case of surgical mortality, and 14 patients have since died from their primary disease an average of 21 months after surgery. Of the patients who are alive, only four (12.5%) have permanent neurological sequelae despite nine patients presenting in a terminal status. In ten cases, radical removal of the tumor resulted in a change in histological diagnosis, usually from a presumed diagnosis of malignancy to a more benign variety (n = 6). Not a single parent expressed regret over the decision to undergo surgery.

CONCLUSION

In the majority of patients, surgical decision making is congruent with the collective opinion of dedicated pediatric neuro-oncological MDT. However, sometimes the surgeon's opinion may be incongruous with MDT recommendation. This series demonstrates the dramatic and favorable potential long-term outcomes that may be achieved with surgery of so-called inoperable lesions.

Knockdown of CypA inhibits interleukin-8 (IL-8) and IL-8-mediated proliferation and tumor growth of glioblastoma cells through down-regulated NF-κB

Although cyclophilin A (CypA) has been reported to be over-expressed in cancer cells and solid tumors, its expression and role in glioblastomas have not been studied. Herein, we show that expression of CypA in human glioblastoma cell lines and tissues is significantly higher than in normal human astrocytes and normal counterparts of brain tissue. To determine the role of over-expressed CypA in glioblastoma, stable RNA interference (RNAi)-mediated knockdown of CypA (CypA KD) was performed in gliobastoma cell line U87vIII (U87MG · ΔEGFR). CypA KD stable single clones decrease proliferation, infiltration, migration, and anchorage-independent growth in vitro and with slower growth in vivo as xenografts in immunodeficient nude mice. We have also observed that knockdown of CypA inhibits expression of interleukin-8 (IL-8), a tumorigenic and proangiogenic cytokine. Conversely, enforced expression of CypA in the CypA KD cell line, Ud-12, markedly enhanced IL-8 transcripts and restored Ud-12 proliferation, suggesting that CypA-mediated IL-8 production provides a growth advantage to glioblastoma cells. CypA knockdown-mediated inhibition of IL-8 is due to reduced activity of NF-κB, which is one of the major transcription factors regulating IL-8 expression. These results not only establish the relevance of CypA to glioblastoma growth in vitro and in vivo, but also suggest that small interfering RNA-based CypA knockdown could be an effective therapeutic approach against glioblastomas.

Modulation of Radiation-Induced Genetic Damage by HCMV in Peripheral Blood Lymphocytes from a Brain Tumor Case-Control Study

Human cytomegalovirus (HCMV) infection occurs early in life and viral persistence remains through life. An association between HCMV infection and malignant gliomas has been reported, suggesting that HCMV may play a role in glioma pathogenesis and could facilitate an accrual of genotoxic damage in the presence of g-radiation; an established risk factor for gliomas. We tested the hypothesis that HCMV infection modifies the sensitivity of cells to γ-radiation-induced genetic damage. We used peripheral blood lymphocytes (PBLs) from 110 glioma patients and 100 controls to measure the level of chromosome damage and cell death. We evaluated baseline, HCMV-, γ-radiation and HCMV + γ-radiation induced genetic instability with the comprehensive Cytokinesis-Blocked Micronucleus Cytome (CBMN-CYT). HCMV, similar to radiation, induced a significant increase in aberration frequency among cases and controls. PBLs infected with HCMV prior to challenge with γ-radiation led to a significant increase in aberrations as compared to baseline, γ-radiation and HCMV alone. With regards to apoptosis, glioma cases showed a lower percentage of induction following in vitro exposure to γ-radiation and HCMV infection as compared to controls. This strongly suggests that, HCMV infection enhances the sensitivity of PBLs to γ-radiation-induced genetic damage possibly through an increase in chromosome damage and decrease in apoptosis.

PPARs in Human Neuroepithelial Tumors: PPAR Ligands as Anticancer Therapies for the Most Common Human Neuroepithelial Tumors

Neuroepithelial tumors represent a heterogeneous class of human tumors including benignant and malignant tumors. The incidence of central nervous system neoplasms ranges from 3.8 to 5.1 cases per 100,000 in the population. Among malignant neuroepithelial tumors, with regard to PPAR ligands, the most extensively studied were tumors of astrocytic origin and neuroblastoma. PPARs are expressed in developing and adult neuroepithelial cells, even if with different localization and relative abundance. The majority of malignant neuroepithelial tumors have poor prognosis and do not respond to conventional therapeutic protocols, therefore, new therapeutic approaches are needed. Natural and synthetic PPAR ligands may represent a starting point for the formulation of new therapeutic approaches to be used as coadjuvants to the standard therapeutic protocols. This review will focus on the major studies dealing with PPAR expression in gliomas and neuroblastoma and the therapeutic implications of using PPAR agonists for the treatment of these neoplasms.

Akt signaling pathway: a target for radiosensitizing human malignant glioma

Radiation therapy plays a central role in the treatment of glioblastoma, but it is not curative due to the high tumor radioresistance. Phosphatidyl-inositol 3-kinase/protein kinase B (Akt) and Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathways serve to block the apoptosis process, keeping cells alive in very toxic environments such as chemotherapy or ionizing radiation. In the present study, from a panel of 8 human malignant glioma cell lines, investigations on the relationship between intrinsic radioresistance and Akt or STAT3 basal activation were done. Secondly, the impact of down-modulation of Akt or STAT3 signaling on in vitro intrinsic radiosensitivity was evaluated. Using a clonogenic cell survival assay, our results revealed a significant correlation between the basal Akt activation and the surviving fraction at 2 Gy (SF2). In contrast, no correlation was found between STAT3 activation and SF2. According to this, down-modulation of Akt with a specific chemical inhibitor (Akt inhibitor IV) demonstrated a significant enhancement of radiation sensitivity on glioma cells in a clonogenic survival assay. On the contrary, down-modulation of STAT3 signaling with a specific chemical inhibitor (JSI-124) or a neutralizing gp130 antibody failed to radiosensitize glioma cells. These data indicate that the Akt intercept node could be a more relevant therapeutic target than STAT3 for radiosensitizing human malignant glioma.

Adipose-derived stem cells as therapeutic delivery vehicles of an oncolytic virus for glioblastoma

Glioblastoma multiforme (GBM) accounts for the majority of primary malignant brain tumors and remains virtually incurable despite extensive surgical resection, radiotherapy, and chemotherapy. Treatment difficulty is due to its exceptional infiltrative nature and proclivity to integrate into normal brain tissue. Long-term survivors are rare, and median survival for patients is about 1 year. Use of adult stem cells as cellular delivery vehicles for anticancer agents is a novel attractive therapeutic strategy. We hypothesized that adipose-derived stem cells (ADSCs) possess the ability to home and deliver myxoma virus to glioma cells and experimental gliomas. We infected ADSCs with vMyxgfp and found them to be permissive for myxoma virus replication. ADSCs supported single and multiple rounds of replication leading to productive infection. Further, we observed no significant impact on ADSC viability. We cocultured fluorescently labeled GBM cells with myxoma virus-infected ADSCs in three-dimensional assay and observed successful cross infection and concomitant cell death almost exclusively in GBM cells. In vivo orthotopic studies injected with vMyxgfp-ADSCs intracranially away from the tumor demonstrated that myxoma virus was delivered by ADSCs resulting in significant survival increase. Our data suggest that ADSCs are promising new carriers of oncolytic viruses, specifically myxoma virus, to brain tumors.

Melatonin sensitizes human malignant glioma cells against TRAIL-induced cell death

Despite the common expression of death receptors, many types of cancer including gliomas are resistant to the death receptor ligand (TRAIL). Melatonin antitumoral actions have been extensively described, including oncostatic properties on several tumor types and improvement of chemotherapeutic regimens. Here, we found that melatonin effectively increase cell sensitivity to TRAIL-induced cell apoptosis in A172 and U87 human glioma cells. The effect seems to be related to a modulation of PKC activity which in turns decreases Akt activation leading to an increase in death receptor 5 (DR5) levels and a decrease in the antiapoptotic proteins survivin and bcl-2 levels.

Therapeutic inhibition of the epidermal growth factor receptor in high-grade gliomas: where do we stand?

High-grade gliomas account for the majority of intra-axial brain tumors. Despite abundant therapeutic efforts, clinical outcome is still poor. Thus, new therapeutic approaches are intensely being investigated. Overexpression of the epidermal growth factor receptor (HER1/EGFR) is found in various epithelial tumors and represents one of the most common molecular abnormalities seen in high-grade gliomas. Dysregulated HER1/EGFR is found in 40% to 50% of glioblastoma, the most malignant subtype of glioma. Several agents such as tyrosine kinase (TK) inhibitors, antibodies, radio-immuno conjugates, ligand-toxin conjugates, or RNA-based agents have been developed to target HER1/EGFR or its mutant form, EGFRvIII. To date, most agents are in various stages of clinical development. Clinical data are sparse but most advanced for TK inhibitors. Although data from experimental studies seem promising, proof of a significant clinical benefit is still missing. Among the problems that have to be further addressed is the prediction of the individual patient's response to HER1/EGFR-targeted therapeutics based on molecular determinants. It is quite possible that blocking HER1/EGFR alone will not sufficiently translate into a clinical benefit. Therefore, a multiple target approach concomitantly aimed at different molecular sites might be a favorable concept. This review focuses on current HER1/EGFR-targeted therapeutics and their development for high-grade gliomas.

[Epidemiology of primary brain tumor]

Two main approaches are generally used to study the epidemiology of primary brain tumors. The first approach is to identify risk factors, which may be intrinsic or related to external causes. The second main approach is descriptive. Intrinsic factors potentially affecting risk include genetic predisposition and susceptibility, gender, race, birth weight and allergy. Radiation exposure is the main extrinsic factor affecting risk. A large body of work devoted, among others, to electromagnetic fields and especially cellular phones, substitutive hormonal therapy, pesticides, and diet have been published. To date, results have been discordant. Descriptive epidemiological studies have reported an increasing annual incidence of primary brain tumors in industrialized countries. The main reasons are the increasing age of the population and better access to diagnostic imaging. Comparing incidences from one registry to another is difficult. Spatial and temporal variations constitute one explanation and evolutions in coding methods another. In all registries, weak incidence of primary brain tumors constitute a very important limiting factor. Renewed interest from the neuro-oncological community is needed to obtain pertinent and essential data which could facilitate improved knowledge on this topic.

BNIP3 (Bcl-2 19 kDa interacting protein) acts as transcriptional repressor of apoptosis-inducing factor expression preventing cell death in human malignant gliomas

The Bcl-2 19 kDa interacting protein (BNIP3) is a pro-cell-death BH3-only member of the Bcl-2 family. We previously found that BNIP3 is localized to the nucleus in the majority of glioblastoma multiforme (GBM) tumors and fails to induce cell death. Herein, we have discovered that nuclear BNIP3 binds to the promoter of the apoptosis-inducing factor (AIF) gene and represses its expression. BNIP3 associates with PTB-associating splicing factor (PSF) and HDAC1 (histone deacetylase 1) contributing to transcriptional repression of the AIF gene. This BNIP3-mediated reduction in AIF expression leads to decreased temozolomide-induced apoptosis in glioma cells. Furthermore, nuclear BNIP3 expression in GBMs correlates with decreased AIF expression. Together, we have discovered a novel transcriptional repression function for BNIP3 causing reduced AIF expression and increased resistance to apoptosis. Thus, nuclear BNIP3 may confer a survival advantage to glioma cells and explain, in part, why BNIP3 is expressed at high levels in solid tumors, especially GBM.

Tyrosine phosphorylation of the human glutathione S-transferase P1 by epidermal growth factor receptor

Epidermal growth factor receptor (EGFR) gene amplification, mutations, and/or aberrant activation are frequent abnormalities in malignant gliomas and other human cancers and have been associated with an aggressive clinical course and a poor therapeutic outcome. Elevated glutathione S-transferase P1 (GSTP1), a major drug-metabolizing and stress response signaling protein, is also associated with drug resistance and poor clinical outcome in gliomas and other cancers. Here, we provide evidence that GSTP1 is a downstream EGFR target and that EGFR binds to and phosphorylates tyrosine residues in the GSTP1 protein in vitro and in vivo. Mass spectrometry and mutagenesis analyses in a cell-free system and in gliomas cells identified Tyr-7 and Tyr-198 as major EGFR-specific phospho-acceptor residues in the GSTP1 protein. The phosphorylation increased GSTP1 enzymatic activity significantly, and computer-based modeling showed a corresponding increase in electronegativity of the GSTP1 active site. In human glioma and breast cancer cells, epidermal growth factor stimulation rapidly increased GSTP1 tyrosine phosphorylation and decreased cisplatin sensitivity. Lapatinib, a clinically active EGFR inhibitor, significantly reversed the epidermal growth factor-induced cisplatin resistance. These data define phosphorylation and activation of GSTP1 by EGFR as a novel, heretofore unrecognized component of the EGFR signaling network and a novel mechanism of tumor drug resistance, particularly in tumors with elevated GSTP1 and/or activated EGFR.

Inhibition of LRIG3 gene expression via RNA interference modulates the proliferation, cell cycle, cell apoptosis, adhesion and invasion of glioblastoma cell (GL15)

LRIG3 (leucine-rich repeats and immunoglobulin-like domains, LRIG) gene is both under-and over-expressed in human cancers and its role on tumor growth is not fully clarified. Here, we used a human U6 promoter-driven DNA template approach to induce short hairpin RNA (shRNA)-triggered RNA interference (RNAi) to block LRIG3 gene expression in the human glioma cell line GL15. Specific knockdown of LRIG3 by shRNA resulted in significantly increase of the GL15 invasion and adhesion activity in vitro and markedly promoted cell growth. LRIG3 repression also induced increment of the proportion of G0/G1 cells and inhibited apoptosis in GL15 cells. Our results demonstrated that RNAi against LRIG3 could effectively down regulate LRIG3 gene expression. LRIG3 might be involved in the regulation of EGFR signaling, and serve as a tumor suppressor gene in the pathogenesis of glioma.

Inhibition of tumor-induced edema by antisense VEGF is mediated by suppressive vesiculo-vacuolar organelles (VVO) formation

Vascular endothelial growth factor (VEGF) is an important regulator of angiogenesis, vasculogenesis and vascular permeability. Edema in glioma tumors is considered one of the most pathological characteristics, but the mechanism of regulating vascular permeability is still unclear. In the present study, tumorigenic mice were generated by subcutaneous injection of glioma cell lines, C6-null cells and stable transfected-C6 cells overexpressing mock vector (C6-mock) and antisense VEGF (C6-VEGF(-/-)). Overexpression of antisense VEGF (C6-VEGF(-/-) mice) significantly suppressed tumor growth, decreased angiogenesis and reduced tumoral edema. Further studies by electron microscope revealed that tumor-induced hyperpermeability was mediated by formation of vesiculo-vacuolar organelles (VVO), specifically reducing the number of vesicle and caveolae in VVO, and this effect was blocked, at least partially, by antisense VEGF. These data show a possible mechanism of tumor-induced hyperpermeability and indicate that blockage of VEGF might contribute to therapeutical strategies for tumor edema.

Identification of a novel switch in the dominant forms of cell adhesion-mediated drug resistance in glioblastoma cells

The failure of malignant cells to undergo apoptosis is a major obstacle in cancer therapy, and thus identifying the underlining molecules involved therein is imperative for improving patient survival. An important mechanism of drug resistance is cell adhesion-mediated drug resistance (CAM-DR). In this study we identify a novel switch by which glioblastoma multiforme (GBM) cells alter the mode of CAM-DR. In the absence of a microenvironmental cue provided by components of the extracellular matrix (ECM), GBM cells are able to employ an alternative, but equally effective, mode of CAM-DR by forming spheres via cell-cell interactions. Intriguingly, when inhibiting cell-cell interactions in the absence of ECM components, either by low cell density or by inhibition of gap junctions (intercellular connexin tunnels) through chemical inhibition with carbenoxyolone or co-incubation with the connexin-mimicking Gap 27 Cx37,43 peptide, GBM cells were sensitized to tumor necrosis factor-related apoptosis-inducing ligand- and CD95-induced apoptosis. By demonstrating that GBM cells can alternate from one form of CAM-DR (cell-substrate tethering) to another (homocellular cell-cell adhesion) and that inhibition of both forms is necessary for apoptosis sensitization, our findings not only have important implications for novel approaches to restore defective apoptosis programs, but also reveal a novel role of gap junctions in GBM.

Expression of MAGE and GAGE genes in medulloblastoma and modulation of resistance to chemotherapy. Laboratory investigation

OBJECT

Cancer testis antigens (CTAs) were initially identified by their ability to elicit autologous T-cell-mediated immune responses in patients with melanoma. The CTA genes are widely expressed in a variety of human cancers, such as melanoma, breast cancer, lung cancer, esophageal cancer, and hepatocellular carcinoma; however, their expression in pediatric brain tumors, such as medulloblastoma (MB), has not been the subject of in-depth analysis. The MAGE proteins are members of the CTA family and have been shown to correlate with tumor development, aggressive clinical course, or resistance to chemotherapeutic agents. The authors undertook this study to examine the expression and role of MAGE proteins in human MB cell lines and specimens.

METHODS

From a transcriptional profiling study in which 47,000 genes in MB cell lines were examined, the authors identified members of the MAGE and GAGE families as being highly expressed. A series of MB tumors was examined using both immunohistochemistry and Western blot analysis with antibodies to the MAGE-A family, MAGE-A1, and GAGE proteins.

RESULTS

Western blot analysis showed expression of these 3 proteins (MAGE-A family, MAGE-A1, and GAGE) in 62, 46, and 84%, respectively, of MB specimens examined. In addition, a correlation was observed between the expression of MAGE and GAGE genes and resistance of MB cells to chemotherapeutic agents. The functional significance of this correlation was examined in MAGE knockdown studies, and increased drug-induced cytotoxicity was observed in UW426 MB cells following treatment with chemotherapeutic drugs. Cleaved caspase-3 was found in UW426/MAGE small interfering (si)RNA-inhibited cells treated with cisplatin, but not in UW426 cells treated with cisplatin alone at the same concentration.

CONCLUSIONS

These data show that MAGE and GAGE family members are expressed in MB cell lines and specimens, and that inhibition of MAGE and GAGE genes by siRNA increases apoptosis of MB cells and sensitizes them to certain chemotherapeutic agents such as cisplatin and etoposide.

Vincristine and lomustine induce apoptosis and p21(WAF1) up-regulation in medulloblastoma and normal human epithelial and fibroblast cells

Medulloblastomas arise in the cerebellum and are the most common pediatric primary malignant brain tumors. Currently, medulloblastoma patients are best treated with surgical removal of the tumor, adjuvant radiation therapy and chemotherapy. The chemotherapeutic agents that showed efficiency against medulloblastomas include lomustine and vincristine. However, the effects of these drugs on medulloblastomas as well as on other cell types is still not well defined. In the present report we present evidence that the cytotoxic effect of these drugs is not specific for medulloblastoma cells but includes also normal fibroblast and epithelial cells. We have also shown that vincristine and lomustine trigger apoptosis in all these cells through the mitochondrial pathway via decrease in the level of the anti-apoptosis proteins Bcl-2 and Bcl-xl, respectively. Intriguingly, the proportion of apoptotic cells induced in medulloblastoma and normal epithelial and fibroblastic cells was similar. In addition, vincristine induced low proportion of necrosis in medulloblastoma and normal fibroblast cells. Interestingly, while vincristine induced cell cycle delay in G2/M phase in normal as well as medulloblastoma cells, lomustine effect on the cell cycle was specific for medulloblastoma cells. Furthermore, we have shown that vincristine and lomustine up-regulated p21 protein level in a p53-independent manner. These results shed more light on the biological effects of vincristine and lomustine and show that lomustine is a more specific and potent anti-medulloblastoma agent.

Subclinical photodynamic therapy treatment modifies the brain microenvironment and promotes glioma growth

Photodynamic therapy (PDT) has been clinically investigated as an adjuvant local therapy for brain tumors. Therapeutic interventions intended to promote tumor cell death can also promote changes in the tumor microenvironment that could favor tumor growth. We have previously shown that PDT can activate pro-angiogenic factors in the normal rodent brain. This study seeks to further elucidate the effects of subtherapeutic doses of Photofrin-PDT on normal brain and to establish a mouse model for studying glioma progression in an environment modified by oxidative stress. Photofrin was administered to nude mice, and a defined intracranial area was illuminated with laser to deliver an optical dose equivalent to 80 J/cm(2). Three and 7 days after PDT, mice were sacrificed and brains were fixed and analyzed by immunohistochemistry. PDT treatment resulted in transient increase in cell proliferation, associated with a robust activation of astrocytes and microglia in the treated region, without causing substantial cell death. To test how this modified environment would affect glioma growth, human glioblastoma U87 cells were implanted in the PDT-treated hemisphere or in the control brain subjected to sham surgery. Significantly larger tumors were observed after 3 weeks in the PDT treated brains relative to control treatment. Our results indicate that subclinical Photofrin-PDT locally alters the brain homeostasis without inflicting significant disruption to the tissue architecture, providing a model to study the effects of the microenvironment on glioma growth, with implications for the optimization of the clinical use of PDT for brain tumors.

Brain tumours and exposure to pesticides: a case-control study in southwestern France

BACKGROUND

Brain tumours are often disabling and rapidly lethal; their aetiology is largely unknown. Among potential risk factors, pesticides are suspected.

OBJECTIVE

To examine the relationship between exposure to pesticides and brain tumours in adults in a population-based case-control study in southwestern France.

METHODS

Between May 1999 and April 2001, 221 incident cases of brain tumours and 442 individually matched controls selected from the general population were enrolled. Histories of occupational and environmental exposures, medical and lifestyle information were collected. A cumulative index of occupational exposure to pesticides was created, based on expert review of lifelong jobs and tasks. Separate analyses were performed for gliomas and meningiomas.

RESULTS

A non-statistically significant increase in risk was found for brain tumours when all types of occupational exposure to pesticides were considered (OR = 1.29, 95% CI 0.87 to 1.91) and slightly higher but still non-statistically significant when gliomas were considered separately (OR = 1.47, 95% CI 0.81 to 2.66). In the highest quartile of the cumulative index, a significant association was found for brain tumours (OR = 2.16, 95% CI 1.10 to 4.23) and for gliomas (OR = 3.21, 95% CI 1.13 to 9.11), but not for meningiomas. A significant increase in risk was also seen for the treatment of home plants (OR = 2.24, 95% CI 1.16 to 4.30) owing to environmental exposure to pesticides.

CONCLUSIONS

These data suggest that a high level of occupational exposure to pesticides might be associated with an excess risk of brain tumours, and especially of gliomas.

Medulloblastoma: tumorigenesis, current clinical paradigm, and efforts to improve risk stratification

Medulloblastoma is the most common brain malignancy in children and tremendous advances have recently been made in understanding the pathogenesis of this tumor. The Hedgehog and Wingless signaling pathways are implicated in medulloblastoma development, and both pathways were discovered as a result of analyses of genetic syndromes associated with the tumor. Over the past 80 years, considerable progress has been made in the treatment of what was once a fatal disease. The first survival reports followed the introduction of craniospinal irradiation, and yet the success of this modality, which continues to be a central component of treatment regimens for patients older than 3 years, comes at a significant cost. The present challenge in medulloblastoma treatment is to improve upon existing survival rates and to minimize the side effects of treatment. The current tools of clinical risk assessment fail to adequately identify patients older than 3 years who require less radiation and those who require more radiation. Significant effort has been made to improve clinical risk stratification and titration of treatment by analyzing properties of the tumor cells themselves for prognostic significance. These efforts include identifying histopathologic, cytogenetic, and molecular features that may correlate with prognosis.

Cellular telephone use and time trends in brain tumour mortality in Switzerland from 1969 to 2002

A rising concern exists that with the widespread use of mobile communication technologies, the incidence of brain tumours may increase. On the basis of data from the Swiss national mortality registry from 1969 to 2002, annual age-standardized brain tumour mortality rates per 100,000 person-years were calculated using the European standard population. Time trend analyses were performed by the Poisson regression for six different age groups in men and women separately. The study period was divided into two intervals: before and after 1987, when the analogue mobile technology was introduced in Switzerland. Age-standardized brain tumour mortality rates ranged between 3.7 and 6.7 for men and 2.5 and 4.4 for women per 100,000 person-years. For the whole study period, a significant increase in brain tumour mortality was observed for men and women in the older age groups (60-74 and 75+ years) but not in the younger ones in whom mobile phone use was more prevalent. Time trend analyses restricted to data from 1987 onwards revealed relatively stable brain tumour mortality rates in all age groups. For instance, the annual change in brain tumour mortality rate for the 45-59-year age group was -0.3% (95% confidence interval: -1.7; 1.1) for men and -0.4% (95% confidence interval:-2.2; 1.3) for women. We conclude that after the introduction of mobile phone technology in Switzerland, brain tumour mortality rates remained stable in all age groups. Our results suggest that mobile phone use is not a strong risk factor in the short term for mortality from brain tumours. Ecological analyses like this, however, are limited in their ability to reveal potentially small increases in risk for diseases with a long latency period.

[Incidence and mortality of central nervous system tumors in France: trends over the period 1978-2000 and influence of registration practices on results]

BACKGROUND

In France, cancer incidence figures are produced by cancer registries covering only 13.5% to 16% of the whole population of the country. Thus, to produce national figures, estimates have to be computed. Registration disparities between registries concerning tumors of the Central Nervous System (CNS) could have biased these estimates.

METHODS

National estimates are based on modelling of the incidence/mortality ratio. The most recent estimations for year 2000 were calculated by the French Cancer Registry Network (FRANCIM) and the department of biostatistics of Lyon University Hospital. Since benign tumors are not recorded in some cancer registries, a new estimate of the incidence of CNS tumors was produced by estimating the number of benign tumors in these registries.

RESULTS

In 2000 in France, the number of estimated cases of CNS tumors was 2697 in men and 2602 in women, with incidence rates (World standard) of 7.4 and 6.4 per 100,000 respectively. The incidence increased between 1978 and 2000, on an average by 2.25% per year in men and 3.01% per year in women. However, these estimates do not provide a correct picture of CNS incidence. First of all, pathological diagnoses are not performed in 3.5%-27.5% of the patients with CNS tumors registered in French registries. Second, figures for benign tumors (mainly meningiomas) were provided by only two of nine cancer registries. If benign tumors had been registered by all cancer registries, computed incidence would have increased by 12% for men and 26% for women.

CONCLUSION

Incidence of CNS tumors is increasing in France, as in many other countries. To improve comparability with other countries, French cancer registries should also collect data on benign tumors. The discrepancies observed between registries in the proportion of patients without information on histology show differences in diagnostic practices and should be the starting point for a survey on this topic.

Rising incidence of primary central nervous system lymphoma in Kumamoto, Japan

BACKGROUND

Primary central nervous system lymphoma is an extranodal form of non-Hodgkin lymphoma arising in the craniospinal axis. The incidence of PCNSL is reportedly on the increase in some parts of the world in the last 2 decades.

METHODS

We surveyed 4007 patients diagnosed with PIT between 1989 and 2004, with histologic diagnosis being obtained in 70% of the patients. Of these, the PCNSL cases were reviewed.

RESULTS

Of 4007, 136 (3.4%) carried a diagnosis of PCNSL. At 0.41 per 100,000 per year, the age-adjusted incidence rate for that period was higher than that for the period from 1989 to 1998 (0.29 per 100,000 per year). Moreover, the number of patients with PCNSL doubled from 45 (1989-1996) to 91 (1997-2004).

CONCLUSIONS

Our findings point to an increase in the incidence of PCNSL among immunocompetent individuals in Kumamoto Prefecture.

Biology of platelet-derived growth factor and its involvement in disease

Platelet-derived growth factor (PDGF) is mainly believed to be an important mitogen for connective tissue, especially for fibroblasts that serve in wound healing. However, PDGF also has important roles during embryonal development, and its overexpression has been linked to different types of fibrotic disorders and malignancies. Platelet-derived growth factor is synthesized by many different cell types, and its expression is broad. Its synthesis is in response to external stimuli, such as exposure to low oxygen tension, thrombin, or stimulation by other cytokines and growth factors. In addition, PDGF may function in autocrine stimulation of tumor cells, regulation of interstitial fluid pressure, and angiogenesis. Recently, several drugs were developed that are potent inhibitors of the tyrosine kinase activity of PDGF receptors. Thus, it is important to understand the physiology of PDGF and its receptors and the role of PDGF in different diseases. This review summarizes the physiologic activity of PDGF, the expression of PDGF during embryonal development, and the roles of PDGF expression in nonmalignant disease and in different tumors.

NF-kappaB-independent sensitization of glioblastoma cells for TRAIL-induced apoptosis by proteasome inhibition

The transcription factor nuclear factor-kappaB (NF-kappaB) is a key regulator of stress-induced transcriptional activation and has been implicated in mediating primary or acquired apoptosis resistance in various cancers. In the present study, we therefore investigated the role of NF-kappaB in regulating apoptosis in malignant glioma, a prototypic tumor refractory to current treatment approaches. Here, we report that constitutive NF-kappaB DNA-binding activity was low or moderate in eight different glioblastoma cell lines compared to Hodgkin's lymphoma cells, known to harbor aberrant constitutive NF-kappaB activity. Specific inhibition of NF-kappaB by overexpression of inhibitor of kappaB (IkappaB)alpha superrepressor did not enhance spontaneous apoptosis of glioblastoma cells. Also, overexpression of IkappaBalpha superrepressor had no significant impact on apoptosis induced by two prototypic classes of apoptotic stimuli, that is, chemotherapeutic drugs or death-inducing ligands such as TNF-related apoptosis inducing ligand (TRAIL), which are known to trigger NF-kappaB activation as part of a cellular stress response. Similarly, inhibition of NF-kappaB by the proteasome inhibitor MG132 did not increase doxorubicin (Doxo)-induced apoptosis of glioblastoma cells, although it prevented DNA binding of NF-kappaB complexes in response to Doxo. Interestingly, proteasome inhibition significantly sensitized glioblastoma cells for TRAIL-induced apoptosis. These findings indicate that the characteristic antiapoptotic function of NF-kappaB reported for many cancers is not a primary feature of glioblastoma and thus, specific NF-kappaB inhibition may not be effective for chemosensitization of glioblastoma. Instead, proteasome inhibitors, which enhanced TRAIL-induced apoptosis in an NF-kappaB-independent manner, may open new perspectives to increase the efficacy of TRAIL-based regimens in glioblastoma, which warrants further investigation.

Trends in brain cancer incidence and survival in the United States: Surveillance, Epidemiology, and End Results Program, 1973 to 2001

OBJECT

An increasing incidence of brain cancer has been reported for the last three decades. In this study of brain cancer incidence and patient survival in the US, the authors attempt to update information on trends by examining data provided by the Surveillance, Epidemiology, and End Results (SEER) Program.

METHODS

Population-based data from the SEER Program were used to calculate the incidence of and survival rates for people with brain cancer. The approximate Poisson method was used to calculate relative risks for brain cancer and to determine a 95% confidence interval. Annual age-standardized incidence rates were calculated, and time-trend analysis was conducted using joinpoint regression analysis. The relative risks of brain cancer were 1.48 for men compared with women, 3.18 for elderly persons compared with young adults, 1.86 for Caucasian patients compared with African-American patients, and 1.35 for those in metropolitan counties compared with those in nonmetropolitan counties. The incidence of brain cancer increased until 1987, when the annual percentage of change reversed direction, decreasing from 1.68 to 20.44%. The elderly experienced an increase until 1985, but their rates were stable thereafter. Rising trends were noticed for glioblastoma multiforme (GBM), oligodendroglioma, anaplastic astrocytoma, medulloblastoma, and mixed glioma, and falling trends were observed for astrocytoma not otherwise specified and malignant glioma. The survival rate for patients with GBM has not shown improvement in the last two decades.

CONCLUSIONS

Increased risk of brain cancer is associated with being male, Caucasian, elderly, and residing in a metropolitan county. The incidence rate of brain cancer in the US is gradually declining, but the rising trend of GBM combined with its poor survival rate is disconcerting and needs further exploration.

Intracranial tumors in adult population of the Varazdin County (Croatia) 1996-2004: a population-based retrospective incidence study

AIM

To estimate the incidence of intracranial tumors in the adult population of the Varazdin County, Croatia, for the 1996-2004 period.

METHODS

SETTING

Varazdin County General Hospital and four university hospitals in Zagreb, the capital of Croatia.

STUDY PERIOD

January 1, 1996 to December 31, 2004. Incident patients: county residents admitted for newly diagnosed intracranial tumors according to the WHO diagnostic criteria. Demographic data were extracted from the 2001 Croatian census. Incidence rates (IRs) per 100,000 person-years (p-y) and annual IRs (per 100,000 persons) were determined and compared as incidence rate ratios (IRRs) with 95% CI.

RESULTS

For primary intracranial tumors (PITs), IR was 12.1/100,000 p-y (95% CI: 10.3-14.2), comparable in men and women. The highest incidence was recorded for glioblastoma (IR 4.8, 3.7-6.2) and meningioma (IR 3.1, 2.2-4.2). The incidence of PIT was somewhat greater than that of metastatic tumors (IRR 1.58, 95% CI: 1.22-2.05, P < 0.001). Metastatic tumors were more frequent in men than in women, especially metastatic lung tumors (IRR 6.08, 2.32-20.16, P < 0.001). IRs of all PIT taken together, neuroepithelial tumors cumulatively, nonepithelial tumors cumulatively, glioblastoma and meningioma were higher in the population aged > or = 40 vs. population aged < or = 39 (all IRRs with 95% CI greater than 1, P < 0.05 or < 0.001), comparable in men and women. Women were somewhat older than men at the time of diagnosis of PIT: median difference -6 years (95.1% CI: -10 to -1, P < 0.05). Annual IRs for all these tumor categories showed increasing trends over the study period.

CONCLUSION

Overall, there was an increasing trend in the incidence of primary intracranial tumors in the Varazdin County. Data did not allow estimation for most of the specific tumor types.

Targeted molecular therapy of GBM

Major advances in molecular biology, cellular biology and genomics have substantially improved our understanding of cancer. Now, these advances are being translated into therapy. Targeted therapy directed at specific molecular alterations is already creating a shift in the treatment of cancer patients. Glioblastoma (GBM), the most common brain cancer of adults, is highly suited for this new approach. GBMs commonly overexpress the oncogenes EGFR and PDGFR, and contain mutations and deletions of tumor suppressor genes PTEN and TP53. Some of these alterations lead to activation of the P13K/Akt and Ras/MAPK pathways, which provide targets for therapy. In this paper, we review the ways in which molecular therapies are being applied to GBM patients, and describe the tools of these approaches: pathway inhibitors, monoclonal antibodies and oncolytic viruses. We describe strategies to: i) target EGFR, its ligand-independent variant EGFRvIII, and PDGFR on the cell surface, ii) inhibit constitutively activate RAS/MAPK and PI3K/Akt signaling pathways, iii) target TP53 mutant tumors, and iv) block GBM angiogenesis and invasion. These new approaches are likely to revolutionize the treatment of GBM patients. They will also present new challenges and opportunities for neuropathology.

The pro-cell death Bcl-2 family member, BNIP3, is localized to the nucleus of human glial cells: Implications for glioblastoma multiforme tumor cell survival under hypoxia

The Bcl-2 nineteen kilodalton interacting protein 3 (BNIP3) is a hypoxia-inducible proapoptotic member of the Bcl-2 family that induces cell death by associating with the mitochondria. Under normal conditions, BNIP3 is expressed in skeletal muscle and in the brain at low levels. In many human solid tumors, BNIP3 is upregulated in hypoxic regions but paradoxically, this BNIP3 expression fails to induce cell death. Herein, we have determined that BNIP3 is primarily localized to the nucleus of glial cells of the normal human brain, as well as in the malignant glioma cell line U251. Upon exposure of U251 cells to hypoxia, BNIP3 expression in the cytoplasm increases and localizes with the mitochondria, contributing to induction of cell death. In contrast, when BNIP3 is forcibly over expressed in the nucleus, it fails to induce cell death. Expression of N-terminal BNIP3 (lacking the transmembrane and conserved domains) in U251 cells blocks hypoxia-induced cell death acting as a dominant negative protein by binding to wild-type BNIP3 and blocking its association with the mitochondria. In glioblastoma multiforme (GBM) tumors, BNIP3 expression is increased in hypoxic regions of the tumor and is primarily localized to the nucleus in approximately 80% of tumors. Hence, BNIP3 is sequestered in the nucleus within the brain but under hypoxic conditions, BNIP3 becomes primarily cytoplasmic, promoting cell death. In GBMs, BNIP3 expression is increased but it remains sequestered in the nucleus in hypoxic regions, thereby blocking BNIP3's ability to associate with the mitochondria, providing tumor cells with a possible survival advantage.

Epidermal growth factor receptor inhibition for the treatment of glioblastoma multiforme and other malignant brain tumours

Gliomas are the most common primary central nervous system tumours and about 55% are glioblastoma multiforme (GBM). Between 40% and 50% of GBM have dysregulated epidermal growth factor receptor (HER1/EGFR), and almost half of these co-express the mutant receptor subtype EGFRvIII, which may contribute to the aggressive and refractory course of GBM. Limited therapeutic options exist for GBM, and recurrence is common. Standard therapy is surgical resection, where possible, and radiotherapy. Adjuvant chemotherapy provides a modest survival benefit. New therapies are essential, and HER1/EGFR-targeted agents may provide a viable strategy. The HER1/EGFR tyrosine kinase inhibitors erlotinib and gefitinib are in advanced clinical development for glioma, and a number of trials are in progress, or have recently been completed. Preliminary results with gefitinib show no objective responses, but do provide evidence of disease control. In contrast, preliminary data with erlotinib appear more encouraging. Erlotinib inhibits wild-type HER1/EGFR and EGFRvIII, which may underlie its promising clinical activity. Other HER1/EGFR-targeted agents are also being investigated for glioma, including monoclonal antibodies, radio-immuno conjugates, ligand-toxin conjugates, antisense oligonucleotides and ribozymes. Further studies will define their clinical potential and hopefully provide new, effective treatments for GBM and other malignant brain tumours.

Genomic and protein expression profiling identifies CDK6 as novel independent prognostic marker in medulloblastoma

PURPOSE

Medulloblastoma is the most common malignant brain tumor in children. Despite multimodal aggressive treatment, nearly half of the patients die as a result of this tumor. Identification of molecular markers for prognosis and development of novel pathogenesis-based therapies depends crucially on a better understanding of medulloblastoma pathomechanisms.

PATIENTS AND METHODS

We performed genome-wide analysis of DNA copy number imbalances in 47 medulloblastomas using comparative genomic hybridization to large insert DNA microarrays (matrix-CGH). The expression of selected candidate genes identified by matrix-CGH was analyzed immunohistochemically on tissue microarrays representing medulloblastomas from 189 clinically well-documented patients. To identify novel prognostic markers, genomic findings and protein expression data were correlated to patient survival.

RESULTS

Matrix-CGH analysis revealed frequent DNA copy number alterations of several novel candidate regions. Among these, gains at 17q23.2-qter (P < .01) and losses at 17p13.1 to 17p13.3 (P = .04) were significantly correlated to poor prognosis. Within 17q23.2-qter and 7q21.2, two of the most frequently gained chromosomal regions, confined amplicons were identified that contained the PPM1D and CDK6 genes, respectively. Immunohistochemistry revealed strong expression of PPM1D in 148 (88%) of 168 and CDK6 in 50 (30%) of 169 medulloblastomas. Overexpression of CDK6 correlated significantly with poor prognosis (P < .01) and represented an independent prognostic marker of overall survival on multivariate analysis (P = .02).

CONCLUSION

We identified CDK6 as a novel molecular marker that can be determined by immunohistochemistry on routinely processed tissue specimens and may facilitate the prognostic assessment of medulloblastoma patients. Furthermore, increased protein-levels of PPM1D and CDK6 may link the TP53 and RB1 tumor suppressor pathways to medulloblastoma pathomechanisms.

Sperm protein 17 is expressed in human nervous system tumours

Background

Human sperm protein 17 (Sp17) is a highly conserved protein that was originally isolated from a rabbit epididymal sperm membrane and testis membrane pellet. It has recently been included in the cancer/testis (CT) antigen family, and shown to be expressed in multiple myeloma and ovarian cancer. We investigated its immunolocalisation in specimens of nervous system (NS) malignancies, in order to establish its usefulness as a target for tumour-vaccine strategies.

Methods

The expression of Sp17 was assessed by means of a standardised immunohistochemical procedure [(mAb/antigen) MF1/Sp17] in formalin-fixed and paraffin embedded surgical specimens of NS malignancies, including 28 neuroectodermal primary tumours (6 astrocytomas, 16 glioblastoma multiforme, 5 oligodendrogliomas, and 1 ependymoma), 25 meningeal tumours, and five peripheral nerve sheath tumours (4 schwannomas, and 1 neurofibroma),.

Results

A number of neuroectodermal (21%) and meningeal tumours (4%) were found heterogeneously immunopositive for Sp17. None of the peripheral nerve sheath tumours was immunopositive for Sp17. The expression pattern was heterogeneous in all of the positive samples, and did not correlate with the degree of malignancy.

Conclusion

The frequency of expression and non-uniform cell distribution of Sp17 suggest that it cannot be used as a unique immunotherapeutic target in NS cancer. However, our results do show the immunolocalisation of Sp17 in a proportion of NS tumour cells, but not in their non-pathological counterparts. The emerging complex function of Sp17 makes further studies necessary to clarify the link between it and immunopositive cells.

Isochromosome breakpoints on 17p in medulloblastoma are flanked by different classes of DNA sequence repeats

Medulloblastoma is a highly malignant embryonal tumor of the cerebellum that accounts for 20%-25% of all intracranial pediatric tumors. The most frequent chromosomal rearrangement in medulloblastoma is isochromosome 17, or i(17q). Its frequency suggests that it serves an important role in tumor pathogenesis, possibly mediated by the disruption or permanent activation of a gene at the breakpoint. To address this question, we performed a detailed analysis of chromosome 17 DNA copy number from 18 medulloblastomas previously shown to carry an apparent i(17q). We identified two breakpoint regions, one well within band 17p11.2 (n = 16) and a second within the pericentromeric region (n = 2). To map the breakpoints more precisely, we constructed a tiling-path matrix-CGH array covering chromosomal band 17p11.2 to the centromere and utilized it to delineate two small breakpoint intervals mapping at Mb 19.0 and 21.7 in seven of the medulloblastomas and in nine hematological neoplasias with i(17q). The former interval contains two breakpoint clusters that each colocalize with a pair of head-to-head inverted DNA sequence repeats, and the latter maps close to a region of alpha-satellite repeats. No consensus coding sequence localizes in these regions. Together, these data strongly suggest that the effects of i(17q) in medulloblastoma are mediated by gene-dosage effects of genes on 17p or 17q rather than by the disruption or deregulation of a "breakpoint" gene. Furthermore, we identified artifacts introduced in DNA copy number data by cross-hybridization of low-copy repeat sequences and discuss the challenge these can pose in the interpretation of diagnostic microarrays.