Suppression of glioblastoma cell growth following antisense oligonucleotide-mediated inhibition of fibroblast growth factor receptor expression

Delivering the Promise of Gene Therapy with Nanomedicines in Treating Central Nervous System Diseases

Central Nervous System (CNS) diseases, such as Alzheimer's diseases (AD), Parkinson's Diseases (PD), brain tumors, Huntington's disease (HD), and stroke, still remain difficult to treat by the conventional molecular drugs. In recent years, various gene therapies have come into the spotlight as versatile therapeutics providing the potential to prevent and treat these diseases. Despite the significant progress that has undoubtedly been achieved in terms of the design and modification of genetic modulators with desired potency and minimized unwanted immune responses, the efficient and safe in vivo delivery of gene therapies still poses major translational challenges. Various non-viral nanomedicines have been recently explored to circumvent this limitation. In this review, an overview of gene therapies for CNS diseases is provided and describes recent advances in the development of nanomedicines, including their unique characteristics, chemical modifications, bioconjugations, and the specific applications that those nanomedicines are harnessed to deliver gene therapies.

Antitumor effect of memantine is related to the formation of the splicing isoform of GLG1, a decoy FGF‑binding protein

Drug repositioning is a strategy for repurposing the approved or investigational drugs that are outside the scope of the original medical indication. Memantine is used as a non‑competitive N‑methyl‑D‑aspartate receptor antagonist to prevent glutamate‑mediated excitotoxicity in Alzheimer's disease, and is one of the promising agents which is utilized for the purpose of cancer therapy. However, the association between memantine and Golgi glycoprotein 1 (GLG1), an intracellular fibroblast growth factor receptor, in cancers has not yet been clarified. The present study analyzed the expression and location of GLG1 in tumor cells treated with memantine. Memantine was found to suppress the growth of malignant glioma and breast cancer cells in a concentration‑dependent manner. The mRNA expression of GLG1 was upregulated in a concentration‑dependent manner, and the splicing variant profiles were altered in all cell lines examined. The results of western blot analysis revealed an increase in the full‑length and truncated forms of GLG1. Moreover, GLG1 spread in the cytosol of memantine‑treated cells, whereas it localized in the Golgi apparatus in control cells. Since GLG1 functions as a decoy FGF receptor, the modulation of GLG1 may prove to be one of the mechanisms underlying the cancer‑suppressive effects of memantine.

Glial Hedgehog signalling and lipid metabolism regulate neural stem cell proliferation in Drosophila

The final size and function of the adult central nervous system (CNS) are determined by neuronal lineages generated by neural stem cells (NSCs) in the developing brain. In Drosophila, NSCs called neuroblasts (NBs) reside within a specialised microenvironment called the glial niche. Here, we explore non-autonomous glial regulation of NB proliferation. We show that lipid droplets (LDs) which reside within the glial niche are closely associated with the signalling molecule Hedgehog (Hh). Under physiological conditions, cortex glial Hh is autonomously required to sustain niche chamber formation. Upon FGF-mediated cortex glial overgrowth, glial Hh non-autonomously activates Hh signalling in the NBs, which in turn disrupts NB cell cycle progression and its ability to produce neurons. Glial Hh's ability to signal to NB is further modulated by lipid storage regulator lipid storage droplet-2 (Lsd-2) and de novo lipogenesis gene fatty acid synthase 1 (Fasn1). Together, our data suggest that glial-derived Hh modified by lipid metabolism mechanisms can affect the neighbouring NB's ability to proliferate and produce neurons.

The role of fibroblast growth factors and their receptors in gliomas: the mutations involved

The central nervous system (CNS) comprises of neurons, which are responsible for impulse transmission, and glial cells, which surround neurons providing protection and nutrition. Glial cells are categorized into astrocytes, oligodendrocytes, microglial cells, and ependymal cells. Tumors forming from glial cells are called gliomas, and they are classified accordingly into astrocytomas, oligodendrogliomas, and ependymomas. Gliomas are characterized by high mortality rates and degree of malignancy, heterogeneity, and resistance to treatment. Among the molecular players implicated in glioma pathogenesis are members of the fibroblast growth factor (FGF) superfamily as well as their receptors (FGFRs). In the present study, we provide a review of the literature on the role of FGFs and FGFRs in glioma pathogenesis. We also demonstrate that FGFs, and particularly FGF1 and FGF2, bear a variety of mutations in gliomas, while FGFRs are also crucially involved. In fact, several studies show that in gliomas, FGFRs bear mutations, mainly in the tyrosine kinase domains. Specifically, it appears that FGFR1-TACC1 and FGFR3-TACC3 fusions are common in these receptors. A better understanding of the mutations and the molecular players involved in glioma formation will benefit the scientific community, leading to the development of more effective and innovative therapeutic approaches.

FGF2: a novel druggable target for glioblastoma?

Introduction: Fibroblast growth factors (FGFs) are key mitogens in tissue homeostasis and cancer. FGF2 regulates self-renewal of multiple stem-cell types, is widely used in stem cell culture paradigms and has been adopted for cultivating the growth of cancer stem cells ex vivo. Research has shed light on the functions of FGF2 in brain tumors, particularly malignant glioma, and this has demonstrated that FGF2 increases self-renewal of glioblastoma stem cells.Areas covered: This review examines the potential targeting of FGF2 signaling as a possible treatment avenue for glioblastoma. The expression of FGF ligands and the FGFR family of receptor tyrosine kinases in the normal brain and in glioblastoma is described. Moreover, the paper sheds light on FGF/FGFR signaling, including the function of heparin/heparan sulfate proteoglycans in facilitating FGF signaling. We speculate on potential avenues for the therapeutic targeting of the FGF2-FGF receptor signaling axis in glioblastoma and the associated challenges envisioned with these approaches.Expert opinion: Precision targeting of FGF/FGFR signaling could improve prospective glioblastoma therapeutics and moderate adverse effects. Shrewd development of experimental models and FGF2 inhibitors could provide a 'pharmacological toolbox' for targeting diverse ligand/receptor combinations.

Fibroblast Growth Factor Receptor Functions in Glioblastoma

Glioblastoma is the most lethal brain cancer in adults, with no known cure. This cancer is characterized by a pronounced genetic heterogeneity, but aberrant activation of receptor tyrosine kinase signaling is among the most frequent molecular alterations in glioblastoma. Somatic mutations of fibroblast growth factor receptors (FGFRs) are rare in these cancers, but many studies have documented that signaling through FGFRs impacts glioblastoma progression and patient survival. Small-molecule inhibitors of FGFR tyrosine kinases are currently being trialed, underlining the therapeutic potential of blocking this signaling pathway. Nevertheless, a comprehensive overview of the state of the art of the literature on FGFRs in glioblastoma is lacking. Here, we review the evidence for the biological functions of FGFRs in glioblastoma, as well as pharmacological approaches to targeting these receptors.

Alpha6-Integrin Regulates FGFR1 Expression through the ZEB1/YAP1 Transcription Complex in Glioblastoma Stem Cells Resulting in Enhanced Proliferation and Stemness

Glioblastoma (GBM) is the most lethal primary brain tumor in adults and is known to be particularly aggressive and resistant to anti-cancer therapies, mainly due to the presence of GBM stem cells (GBMSC). By in vitro approaches supported by analysis from patients' databases, we determined how α6-integrin and Fibroblast Growth Factor Receptor 1 (FGFR1) work in concert to regulate proliferation and stemness of GBMSC. We showed that α6-integrin regulates the expression of FGFR1 and its target gene Fokhead Box M1 (FOXM1) via the ZEB1/YAP1 transcription complex. These results were in accordance with the positive correlation observed in GBM between α6-integrin expression and its target genes ZEB1/YAP1, FGFR1, and FOXM1 in the databases, TCGA and Rembrandt. In addition, the clinical data demonstrate that GBM patients with high levels of the five genes signature, including α6-integrin, ZEB1/YAP1, FGFR1 and FOXM1, have a significantly shorter overall survival. In vitro, we observed a similar decrease in the expression of stemness-related factors, neurospheres forming capacity, as well as spheroids growth when α6-integrin or FGFR1 was blocked individually with specific siRNA, whereas the combination of both siRNA led to a significantly higher inhibition of spheres formation. These data suggest that co-administration of anti-FGFR1 and anti-α6-integrin could provide an improved therapeutic response in GBMSC.

Depression and glioblastoma, complicated concomitant diseases: a systemic review of published literature

Glioblastoma multiforme (GBM) is the most common primary brain cancer. Depression is a common co-morbidity of this condition. Despite this common interaction, relatively little research has been performed on the development of GBM-associated depression. We performed a literary search of the PubMed database for articles published relating to GBM and depression. A total of 85 articles were identified with 46 meeting inclusion criteria. Depression significantly impacts care, decreasing medication compliance, and patient survival. Diagnostically, because depression and GBM share intricate neuro-connectivity in a way that effect functionality, these diseases can be mistaken for alternative psychological or pathological disorders, complicating care. Therapeutically, anti-depressants have anti-tumor properties; yet, some have been shown to interfere with GBM treatment. One reason for this is that the pathophysiological development of depression and GBM share several pathways including altered regulation of the 5-HT receptor, norepinephrine, and 3':5'-cyclic monophosphate. Over time, depression can persist after GBM treatment, affecting patient quality of life. Together, depression and GBM are complicated concomitant diseases. Clinicians must be aware of their co-existence. Because of overlapping molecular pathways involved in both diseases, careful medication selection is imperative to avoid potential adverse interactions. Since GBMs are the most common primary brain cancer, physicians dealing with this disease should be prepared for the development of depression as a potential sequela of this condition, given the related pathophysiology and the known poor outcomes.

Downregulation of fibroblast growth factor receptor 2 and its isoforms correlates with a high proliferation rate and poor prognosis in high-grade glioma

Fibroblast growth factor receptor 2 (FGFR-2) contributes to the progression of numerous types of cancers; however, its role in glioma has yet to be determined. We investigated the expression of FGFR-2 and its predominant isoforms, FGFR-2 IIIb and FGFR-2 IIIc, in gliomas of all histological grades. Using immunohistochemistry, we demonstrated that FGFR-2, FGFR-2 IIIb and FGFR-2 IIIc were expressed in the astrocytes of normal human brains. The percentages of cells expressing FGFR-2, FGFR-2 IIIb and FGFR-2 IIIc and the intensities of their staining in glioblastomas (grade IV) were significantly reduced when compared to these parameters in the low-grade tumors (grade I, II and III; P<0.05). A high MIB-1 index, indicated by Ki-67 expression in >20% of the cells, was also associated with low expression of each FGFR-2 protein. Lower expression of FGFR-2 and FGFR-2 IIIc was correlated with a reduced survival rate (P=0.02 and 0.0253, respectively). Quantitative PCR analysis confirmed that the mRNA levels of FGFR-2 IIIb and FGFR-2 IIIc in a high-grade glioma-derived cell line (YKG-1) were lower than levels in a low-grade glioma-derived cell line (KG-1-C). These findings suggest that the decrease or loss of FGFR-2, FGFR-2 IIIb and FGFR-2 III in high-grade gliomas correlates with poor prognosis, which we attribute to the high proliferation rate of the tumor.

Design, synthesis and biological evaluation of naphthostyril derivatives as novel protein kinase FGFR1 inhibitors

New class of FGFR1 kinase inhibitors with naphthostyril heterocycle has been identified. A series of N-phenylnaphthostyril-1-sulfonamides has been synthesized and tested in vitro. It was revealed that the most active compound N-(4-hydroxyphenyl)naphthostyril-1-sulfonamide inhibited FGFR1 with IC50 of 2 µM. In our preliminary studies, N-phenylnaphthostyril-1-sulfonamides demonstrated selectivity of FGFR1 inhibition and antiproliferative activity on cancer cell line. N-phenylnaphthostyril-1-sulfonamides have a good potential for further development as anticancer agents.

The role of CXCR4 in highly malignant human gliomas biology: current knowledge and future directions

Given the extensive histomorphological heterogeneity of high-grade gliomas, in terms of extent of invasiveness, angiogenesis, and necrosis and the poor prognosis for patients despite the advancements made in therapeutic management. The identification of genes associated with these phenotypes will permit a better definition of glioma heterogeneity, which may ultimately lead to better treatment strategies. CXCR4, a cell surface chemokine receptor, is implicated in the growth, invasion, angiogenesis and metastasis in a wide range of malignant tumors, including gliomas. It is overexpressed in glioma cells according to tumor grade and in glioma tumor initiating cells. There have been various reports suggesting that CXCR4 is required for tumor proliferation, invasion, angiogenesis, and modulation of the immune response. It may also serve as a prognostic factor in characterizing subsets of glioblastoma multiforme, as patients with CXCR4-positive gliomas seem to have poorer prognosis after surgery. Aim of this review was to analyze the current literature on biological effects of CXCR4 activity and its role in glioma pathogenesis. A better understanding of CXCR4 pathway in glioma will lead to further investigation of CXCR4 as a novel putative therapeutic target.

Dissecting Pin1 and phospho-pRb regulation

The activity of the Retinoblastoma protein, the master regulator of the cell cycle, is finely regulated by phosphorylation. CDKs and cyclins are major players in phosphorylation and it has been recently discovered that the prolyl isomerase Pin1 is an essential protein that orchestrates this process. In this article, we report new findings regarding the role of Pin1 in the pRb pathway. Our data suggest that PI3K, CDKs, and the Pin1 axis have a critical role in sustaining the complete phosphorylation of pRb. Furthermore, we analyze the correlation between Pin1 and pRb phosphorylation in vivo. We show that, in human malignant glioma tissue microarrays (TMA) and in Pin1 knockout (KO) mice, there is a positive correlation between Pin1 and pRb phosphorylation. Prospectively, our findings suggest that the synergism between CDKs, Pin1, and PI3K inhibitors hold great promise for targeted pharmacological treatment of cancer patients, with the possibility of reaching high effectiveness at tolerated doses.

Glioblastoma cell growth is suppressed by disruption of Fibroblast Growth Factor pathway signaling

The Fibroblast Growth Factor (FGF) signaling pathway is reported to stimulate glioblastoma (GBM) growth. In this work we evaluated the effect of FGF2, FGF receptor (FGFR), and small molecule inhibition on GBM cells grown in traditional media, or cultured directly in stem-cell media. These lines each expressed the FGFR1, FGFR3 and FGFR4 receptors. Addition of FGF2 ligand showed significant growth stimulation in 8 of 10 cell lines. Disruption of FGF signaling by a neutralizing FGF2 monoclonal antibody and FGFR1 suppression by RNA interference both partially inhibited cell proliferation. Growth inhibition was temporally correlated with a reduction in MAPK signaling. A receptor tyrosine kinase inhibitor with known FGFR/VEGFR activity, PD173074, showed reproducible growth inhibition. Possible mechanisms of growth suppression by PD173074 were implicated by reduced phosphorylation of AKT and MAPK, known oncogenic signal transducers. Subsequent reduction in the cyclin D1, cyclin D2 and CDK4 cell cycle regulators was also observed. Our results indicate that FGF signaling pathway inhibition as a monotherapy will slow, but not arrest growth of glioblastoma cells.

EphA4 promotes cell proliferation and migration through a novel EphA4-FGFR1 signaling pathway in the human glioma U251 cell line

The Eph receptor tyrosine kinases and their ephrin ligands form a unique cell-cell contact-mediated bidirectional signaling mechanism for regulating cell localization and organization. High expression of Eph receptors in a wide variety of human tumors indicates some roles in tumor progression, which makes these proteins potential targets for anticancer therapy. For this purpose, we did gene expression profiling for 47 surgical specimens of brain tumors including 32 high-grade glioma using a microarray technique. The analysis, focused on the receptor tyrosine kinases, showed that EphA4 mRNA in the tumors was 4-fold higher than in normal brain tissue. To investigate the biological significance of EphA4 overexpression in these tumors, we analyzed EphA4-induced phenotypic changes and the signaling mechanisms using human glioma U251 cells. EphA4 promoted fibroblast growth factor 2-mediated cell proliferation and migration accompanied with enhancement of fibroblast growth factor 2-triggered mitogen-activated protein kinase and Akt phosphorylation. In addition, active forms of Rac1 and Cdc42 increased in the EphA4-overexpressing cells. Furthermore, we found that EphA4 formed a heteroreceptor complex with fibroblast growth factor receptor 1 (FGFR1) in the cells and that the EphA4-FGFR1 complex potentiated FGFR-mediated downstream signaling. Thus, our results indicate that EphA4 plays an important role in malignant phenotypes of glioblastoma by enhancing cell proliferation and migration through accelerating a canonical FGFR signaling pathway.

Molecular and cell biology of brain tumor stem cells: lessons from neural progenitor/stem cells

✓ The results of studies conducted in the past several years have suggested that malignant brain tumors may harbor a small fraction of tumor-initiating cells that are likely to cause tumor recurrence. These cells are known as brain tumor stem cells (BTSCs) because of their multilineage potential and their ability to self-renew in vitro and to recapitulate original tumors in vivo. The understanding of BTSCs has been greatly advanced by knowledge of neural progenitor/stem cells (NPSCs), which are multipotent and self-renewing precursor cells for neurons and glia. In this article, the authors summarize evidence that genetic mutations that deregulate asymmetric cell division by affecting cell polarity, spindle orientation, or cell fate determinants may result in the conversion of NPSCs to BTSCs. In addition, they review evidence that BTSCs and normal NPSCs may reside in similar vascularized microenvironments, where similar evolutionarily conserved signaling pathways control their proliferation. Finally, they discuss preliminary evidence that mechanisms of BTSC-associated infiltrativeness may be similar to those underlying the migration of NPSCs and neurons.

Hyperoxia retards growth and induces apoptosis, changes in vascular density and gene expression in transplanted gliomas in nude rats

This study describes the biological effects of hyperoxic treatment on BT4C rat glioma xenografts in vivo with special reference to tumor growth, angiogenesis, apoptosis, general morphology and gene expression parameters. One group of tumor bearing animals was exposed to normobaric hyperoxia (1 bar, pO(2) = 1.0) and another group was exposed to hyperbaric hyperoxia (2 bar, pO(2) = 2.0), whereas animals housed under normal atmosphere (1 bar, pO(2) = 0.2) served as controls. All treatments were performed at day 1, 4 and 7 for 90 min. Treatment effects were determined by assessment of tumor growth, vascular morphology (immunostaining for von Willebrand factor), apoptosis by TUNEL staining and cell proliferation by Ki67 staining. Moreover, gene expression profiles were obtained and verified by real time quantitative PCR. Hyperoxic treatment caused a approximately 60% reduction in tumor growth compared to the control group after 9 days (p < 0.01). Light microscopy showed that the tumors exposed to hyperoxia contained large "empty spaces" within the tumor mass. Moreover, hyperoxia induced a significant increase in the fraction of apoptotic cells ( approximately 21%), with no significant change in cell proliferation. After 2 bar treatment, the mean vascular density was reduced in the central parts of the tumors compared to the control and 1 bar group. The vessel diameters were significantly reduced (11-24%) in both parts of the tumor tissue. Evidence of induced cell death and reduced angiogenesis was reflected by gene expression analyses.Increased pO(2)-levels in experimental gliomas, using normobaric and moderate hyperbaric oxygen therapy, caused a significant reduction in tumor growth. This process is characterized by enhanced cell death, reduced vascular density and changes in gene expression corresponding to these effects.

Sequence survey of receptor tyrosine kinases reveals mutations in glioblastomas

It is now clear that tyrosine kinases represent attractive targets for therapeutic intervention in cancer. Recent advances in DNA sequencing technology now provide the opportunity to survey mutational changes in cancer in a high-throughput and comprehensive manner. Here we report on the sequence analysis of members of the receptor tyrosine kinase (RTK) gene family in the genomes of glioblastoma brain tumors. Previous studies have identified a number of molecular alterations in glioblastoma, including amplification of the RTK epidermal growth factor receptor. We have identified mutations in two other RTKs: (i) fibroblast growth receptor 1, including the first mutations in the kinase domain in this gene observed in any cancer, and (ii) a frameshift mutation in the platelet-derived growth factor receptor-alpha gene. Fibroblast growth receptor 1, platelet-derived growth factor receptor-alpha, and epidermal growth factor receptor are all potential entry points to the phosphatidylinositol 3-kinase and mitogen-activated protein kinase intracellular signaling pathways already known to be important for neoplasia. Our results demonstrate the utility of applying DNA sequencing technology to systematically assess the coding sequence of genes within cancer genomes.

Correction of aberrant FGFR1 alternative RNA splicing through targeting of intronic regulatory elements

Alternative RNA splicing is now known to be pervasive throughout the genome and a target of human disease. We evaluated if targeting intronic splicing regulatory sequences with antisense oligonucleotides could be used to correct aberrant exon skipping. As a model, we targeted the intronic silencing sequence (ISS) elements flanking the alternatively spliced alpha-exon of the endogenous fibroblast growth factor receptor 1 (FGFR1) gene, which is aberrantly skipped in human glioblastoma. Antisense morpholino oligonucleotides targeting either upstream or downstream ISS elements increased alpha-exon inclusion from 10% up to 70% in vivo. The effect was dose dependent, sequence specific and reproducible in several human cell lines, but did not necessarily correlate with blocking of protein association in vitro. Simultaneous targeting of the ISS elements had no additive effect, suggesting that splicing regulation occurred through a shared mechanism. Broad applicability of this approach was demonstrated by similar targeting of the ISS elements of the human hnRNPA1 gene. The correction of FGFR1 gene splicing to >90% alpha-exon inclusion in glioblastoma cells had no discernable effect on cell growth in culture, but was associated with an increase in unstimulated caspase-3 and -7 activity. The ability to manipulate endogenously expressed mRNA variants allows exploration of their functional relevance under normal and diseased physiological states.

Perlecan and tumor angiogenesis

Perlecan is a major heparan sulfate proteoglycan (HSPG) of basement membranes (BMs) and connective tissues. The core protein of perlecan is divided into five domains based on sequence homology to other known proteins. Commonly, the N-terminal domain I of mammalian perlecan is substituted with three HS chains that can bind a number of matrix molecules, cytokines, and growth factors. Perlecan is essential for metazoan life, as shown by genetic manipulations of nematodes, insects, and mice. There are also known human mutations that can be lethal. In vertebrates, new functions of perlecan emerged with the acquisition of a closed vascular system and skeletal connective tissues. Many of perlecan's functions may be related to the binding and presentation of growth factors to high-affinity tyrosine kinase (TK) receptors. Data are accumulating, as discussed here, that similar growth factor-mediated processes may have unwanted promoting effects on tumor cell proliferation and tumor angiogenesis. Understanding of these attributes at the molecular level may offer opportunities for therapeutic intervention.

Autocrine signaling through Ras regulates cell survival activity in human glioma cells: potential cross-talk between Ras and the phosphatidylinositol 3-kinase-Akt pathway

Autocrine fibroblast growth factor (FGF) signaling mediates an uncontrollable growth of human gliomas. We investigated the intracellular signaling of FGF on cell survival activity. U251MG human glioma cells were infected with adenovirus vectors expressing dominant negative type I FGF receptor (DNFR), constitutive active Ras (RasL61), or dominant negative Ras (RasN17). DNFR reduced glioma cell accumulation with apoptosis and this reduction was alleviated with exogenous epidermal growth factor (EGF), which can activate Ras independent of FGFR but not with bFGF. RasL61 prevented but RasN17-enhanced DNFR-induced apoptosis. Reportedly, cell survival signaling through Akt was constitutively active in U251MG cells and this effect may be dependent on autocrine signaling and dysfunction of PTEN, a tumor suppressor gene limiting phosphatidylinositol 3-kinase (PI3K) activity. DNFR dose-dependently inhibited Akt activity and this inhibition was recovered by RasL61, whereas RasN17 inhibited Akt activity. Wortmannin (a PI3K inhibitor) inhibited Akt activity and mildly promoted apoptosis. RasL61 prevented the down-regulation of Akt activity and apoptosis induced by wortmannin, but RasN17 plus wortmannin strongly inhibited Akt activity and promoted marked apoptosis. Our data suggested that the cell survival activity of human gliomas is largely dependent on cross-talk between Ras and the PI3K-Akt pathway, and this cross-talk could be a potential target for molecular-based therapeutics.

Fibroblast growth factor receptor (FGFR) 4 correlated with the malignancy of human astrocytomas

Fibroblast growth factor receptor (FGFR) 4 possesses high affinity to acidic and basic fibroblast growth factors (FGFs). The authors focused on FGFR 4 expression in astrocytoma because the FGF expression increases as the tumor malignancy progresses. Forty-one astrocytoma specimens were examined by immunohistochemistry and polymerase chain reaction-Southern blot. FGFR 4 was negative in all seven Grade II astrocytomas by immunohistochemistry, while positive in four among 15 Grade III and in 13 among 19 Grade IV astrocytomas. The median survival time of Grade III astrocytoma patients was 22.3 months in FGFR 4 negative group and 14.5 months in positive group (p < 0.05). Those of Grade IV patients were 14.2 months in FGFR 4 negative group and 11.9 months in positive group (p > 0.05, not significant). However, FGFR 4 mRNA was detected in all specimens suggesting activated translation system of FGFR 4 in progression of the tumor malignancy. Histologically diagnosed Grade III astrocytoma patients can be divided into two groups; one with median survival time close to those with Grade II astrocytoma patients, and the other similar to that of glioblastoma patients. The authors concluded that FGFR 4 must be an important factor which predicts short survival Grade III astrocytoma patients, who require strict adjuvant therapy in accordance with glioblastoma.

Histological and genetic diagnosis of gliomatosis cerebri: case report

Gliomatosis cerebri is considered grade III astrocytoma because of the short survival period of patients with this tumor, while the tumor histologically consists of widespread low grade astrocytoma cells. The authors tried to clarify this discrepancy by applying genetic analysis of the tumor. A 29-year-old man originally presented with mild headache and showed diffuse high intensity areas in both hemispheres and in the cerebellum by T2-weighted magnetic resonance imaging (MRI) without gadolinium-dimeglumine (Gd)-enhancement in T1-weighted imaging. Histological diagnosis was gliomatosis cerebri with diffuse grade II astrocytoma. Seven months after temporary improvement following irradiation and chemotherapy, he developed progressive mental deterioration, and died in one year after the surgery. At this time T1-weighted imaging showed Gd-enhanced lesions with enlargement only of the cerebellar tumor. Genetic analysis demonstrated positive FGFR 1 and less FGFR 2 mRNA in the tumor tissue, and FGFR 1 mRNA was beta type dominant. These results indicated that the genetic features of this tumor are similar to those of glioblastoma multiforme concerning FGFR expression. The authors conclude that genetic investigation of the tumor tissue is required to predict the prognosis of gliomatosis cerebri patients, in addition to imaging and histological examinations.

Mitogenic signaling and the relationship to cell cycle regulation in astrocytomas

The activity and regulation of a number of mitogenic signaling pathways is aberrant in astrocytomas, and this is thought to play a crucial role in the development of these tumors. The cascade of events leading to the formation and the progression from low-grade to high-grade astrocytomas is well characterized. These events include activating mutations, amplification, and overexpression of various growth factor receptors (e.g. epidermal growth factor receptor (EGFR), platelet derived growth factor receptor (PDGFR), c-Met), signaling intermediates (e.g. Ras and Protein kinase C (PKC)), and cell cycle regulatory molecules (e.g. mouse double minute-2 (Mdm2), cyclin-dependent kinase-4 (CDK4), and CDK6), that positively regulate proliferation and cell cycle progression. Inactivating mutations and deletions of signaling and cell cycle regulatory molecules that negatively regulate proliferation and cell cycle progression (e.g. p53, p16/INK4a, p14/ARF, p15/INK4b, retinoblastoma protein (Rb), and Phosphatase and tensin homologue deleted from chromosome 10 (PTEN)) also participate actively in the development of the transformed phenotype. Several mitogenic pathways are also stimulated via an autocrine loop, with astrocytoma cells expressing both the receptors and the respective cognate ligand. Due to the multitude of factors involved in astrocytoma pathogenesis, attempts to target a single pathway have not given satisfactory results. The simultaneous targeting of several pathways or the targeting of signaling intermediates, such as Ras or PKC, situated downstream of many growth factor receptor signaling pathways may show more efficacy in astrocytoma therapy. We will give an overview of how the combination of these aberrations drive astrocytoma cells into a relentless proliferation and how these signaling molecules may constitute relevant therapeutic targets.