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Malignant Brain Tumors (malignant + brain_tumor)
Selected AbstractsmiR-29b and miR-125a regulate podoplanin and suppress invasion in glioblastomaGENES, CHROMOSOMES AND CANCER, Issue 11 2010Maria Angelica Cortez Glioblastoma is the most frequent and malignant brain tumor, characterized by an elevated capacity for cellular proliferation and invasion. Recently, it was demonstrated that podoplanin membrane sialo-glycoprotein encoded by PDPN gene is over-expressed and related to cellular invasion in astrocytic tumors; however the mechanisms of regulation are still unknown. MicroRNAs are noncoding RNAs that regulate gene expression and several biological processes and diseases, including cancer. Nevertheless, their roles in invasion, proliferation, and apoptosis of glioblastoma are not completely understood. In this study, we focused on miR-29b and miR-125a, which were predicted to regulate PDPN, and demonstrated that these microRNAs directly target the 3, untranslated region of PDPN and inhibit invasion, apoptosis, and proliferation of glioblastomas. Furthermore, we report that miR-29b and miR-125a are downregulated in glioblastomas and also in CD133-positive cells. Taken together, these results suggest that miR-29b and miR-125a represent potential therapeutic targets in glioblastoma. © 2010 Wiley-Liss, Inc. [source] Chemistry, biological activity, and chemotherapeutic potential of betulinic acid for the prevention and treatment of cancer and HIV infectionMEDICINAL RESEARCH REVIEWS, Issue 1 2004Robert H. Cichewicz Abstract 3,-Hydroxy-lup-20(29)-en-28-oic acid (betulinic acid) is a pentacyclic lupane-type triterpene that is widely distributed throughout the plant kingdom. A variety of biological activities have been ascribed to betulinic acid including anti-inflammatory and in vitro antimalarial effects. However, betulinic acid is most highly regarded for its anti-HIV-1 activity and specific cytotoxicity against a variety of tumor cell lines. Interest in developing even more potent anti-HIV agents based on betulinic acid has led to the discovery of a host of highly active derivatives exhibiting greater potencies and better therapeutic indices than some current clinical anti-HIV agents. While its mechanism of action has not been fully determined, it has been shown that some betulinic acid analogs disrupt viral fusion to the cell in a post-binding step through interaction with the viral glycoprotein gp41 whereas others disrupt assembly and budding of the HIV-1 virus. With regard to its anticancer properties, betulinic acid was previously reported to exhibit selective cytotoxicity against several melanoma-derived cell lines. However, more recent work has demonstrated that betulinic acid is cytotoxic against other non-melanoma (neuroectodermal and malignant brain tumor) human tumor varieties. Betulinic acid appears to function by means of inducing apoptosis in cells irrespective of their p53 status. Because of its selective cytotoxicity against tumor cells and favorable therapeutic index, even at doses up to 500 mg/kg body weight, betulinic acid is a very promising new chemotherapeutic agent for the treatment of HIV infection and cancer. © 2003 Wiley Periodicals, Inc. Med Res Rev, 24, No. 1, 90,114, 2004 [source] Influence of high-dose methotrexate therapy (HD-MTX) on glomerular and tubular kidney functionPEDIATRIC BLOOD & CANCER, Issue 6 2003Lutz Hempel MD Abstract Background The present investigation was intended to further clarify the mechanisms involved in renal dysfunction following high-dose methotrexate (HD-MTX) treatment. Patients and Methods Fifty eight predominately pediatric patients [39 male, 19 female; mean age 12.3 years (range 2.2,34.1)] suffering from acute lymphoblastic leukemia (ALL, n,=,28), Non Hodgkins lymphoma (NHL, n,=,13), osteosarcoma (n,=,8), malignant brain tumor (n,=,6), or an ALL relapse (n,=,3), were prospectively examined. In the course of 220 infusions of HD-MTX, glomerular and tubular renal function was determined by measuring proteinuria and glomerular filtration rate (GFR), as well as renal excretion of alpha-1-microglobulin (AMG) and N -acetyl-,- D -glucosaminidase (NAG). It was investigated whether there were differences in MTX toxicity in dependence on the administered dose (1, 5, or 12 g/m2 BSA), on the combination with other cytostatic agents (ifosfamide or cyclophosphamide), on the metabolism of MTX into 7-OH-MTX, and on pre-treatment with MTX. Results The administration of HD-MTX has no direct tubulotoxic effect. The disturbance in glomerular function was dose dependently and indicated by an increase in proteinuria as well as by a decrease in GFR; all changes were completely reversible and did not correlate to the metabolism of MTX to 7-OH-MTX. Increasing the number of MTX therapeutic cycles did not increase the nephrotoxicity of MTX. Conclusion MTX is not directly tubulotoxic. Its side effects on glomeruli are usually without clinical relevance. Med Pediatr Oncol 2003;40:348,354. © 2003 Wiley-Liss, Inc. [source] 99mTc-MIBI imaging for prediction of therapeutic effects of second-generation MDR1 inhibitors in malignant brain tumorsINTERNATIONAL JOURNAL OF CANCER, Issue 12 2007Toshio Sasajima Abstract The aim of this study was to explore whether 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) is suitable to elucidate multidrug resistance and prediction of potentiation of antitumor agents by second-generation MDR1 inhibitors (PSC833, MS-209) in malignant brain tumors in rat. Malignant tumor cells (RG2 and C6 gliomas, Walker 256 carcinoma) were incubated with low dose vincristine (VCR) to induce multidrug resistance. MTT assay demonstrated a significant increase of surviving fractions in VCR-resistant sublines compared to those of drug-naive cells. Reverse transcriptase polymerase chain reaction revealed higher expression of MDR1 mRNA in VCR-resistant cells than drug-naive cells in each line. Volume distribution (Vd) of 99mTc-MIBI was negatively correlated with MDR1 mRNA expression among drug-naive and VCR-resistant cells. MDR1 inhibitors decreased surviving fractions and increased Vd of 99mTc-MIBI significantly in VCR-resistant sublines, whereas MDR1 mRNA expression was unchanged. These findings indicate that 99mTc-MIBI efflux was functionally suppressed by MDR1 inhibitors. Autoradiographic images of 99mTc-MIBI revealed higher uptake in drug-naive cells at basal ganglia compared with VCR-resistant cells at the opposite basal ganglia of rats. Oral administration of the second-generation MDR1 inhibitors significantly increased 99mTc-MIBI accumulation of both tumors. Therapeutic effects of VCR with or without the MDR1 inhibitors were also evaluated autoradiographically using 14C-methyl- L -methionine (14C-Met) and MIB-5 index. 14C-Met uptake and MIB-5 index of both tumors treated with VCR following the MDR1 inhibitor treatment significantly decreased compared with tumors treated with VCR alone. Analysis of 99mTc-MIBI accumulation is considered informative for detecting MDR1-mediated drug resistance and for monitoring the therapeutic effects of MDR1 inhibitors in malignant brain tumors. © 2007 Wiley-Liss, Inc. [source] Mutations of the Wnt antagonist AXIN2 (Conductin) result in TCF-dependent transcription in medulloblastomasINTERNATIONAL JOURNAL OF CANCER, Issue 2 2007Arend Koch Abstract Medulloblastomas (MBs) represent the most common malignant brain tumors in children. Most MBs develop sporadically in the cerebellum, but their incidence is highly elevated in patients with familial adenomatous polyposis coli. These patients carry germline mutations in the APC tumor suppressor gene. APC is part of a multiprotein complex involved in the Wnt signaling pathway that controls the stability of ,-catenin, the central effector in this cascade. Previous genetic studies in MBs have identified mutations in genes coding for ,-catenin and its partners, APC and AXIN1, which cause activation of Wnt signaling. The pathway is negatively controlled by the tumor suppressor AXIN2 (Conductin), a scaffold protein of this signaling complex. To investigate whether alterations in AXIN2 may also be involved in the pathogenesis of sporadic MBs, we performed a mutational screening of the AXIN2 gene in 116 MB biopsy samples and 11 MB cell lines using single-strand conformation polymorphism and sequencing analysis. One MB displayed a somatic, tumor-specific 2 bp insertion in exon 5, leading to carboxy-terminal truncation of the AXIN2 protein. This tumor biopsy showed nuclear accumulation of ,-catenin protein, indicating an activation of Wnt signaling. In 2 further MB biopsies, mutations were identified in exon 5 (Glu408Lys) and exon 8 (Ser738Phe) of the AXIN2 gene, which are due to predicted germline mutations and rare polymorphisms. mRNA expression analysis in 22 MBs revealed reduced expression of AXIN2 mRNA compared to 8 fetal cerebellar tissues. Promoter hypermethylation could be ruled out as a major cause for transcriptional silencing by bisulfite sequencing. To study the functional role of AXIN2 in MBs, wild-type AXIN2 was overexpressed in MB cell lines in which the Wnt signaling pathway was activated by Wnt-3a. In this assay, AXIN2 inhibited Wnt signaling demonstrated in luciferase reporter assays. In contrast, overexpression of mutated AXIN2 with a deleted C-terminal DIX-domain resulted in an activation of the Wnt signaling pathway. These findings indicate that mutations of AXIN2 can lead to an oncogenic activation of the Wnt pathway in MBs. © 2007 Wiley-Liss, Inc. [source] Glucocorticoids enhance interleukin-4 production to neo-antigen (hyaluronidase) in children immunocompromised with cytostatic drugsPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 5 2002Monika Edelbauer Immunoglobulin E (IgE)-mediated immediate-type allergic reactions to hyaluronidase have been observed in children with central nervous system (CNS) tumors. Glucocorticoids, used as therapy for brain edema, are discussed controversially as T helper 2 (Th2) stimulatory factors. In this study we investigated the role of glucocorticoids on a Th2 cytokine-promoting effect in children with CNS tumors. Peripheral blood mononuclear cells (PBMCs) from: 29 children suffering from malignant brain tumors, of whom 23 received short-term glucocorticoid treatment (for 3,4 days) during the course of chemotherapy; 18 children with nephrotic syndrome or renal transplantation receiving long-term glucocorticoid treatment; and 13 healthy children, were incubated with phytohemagglutinin (PHA) and/or anti-CD28 monoclonal antibody (mAb) and, in a second approach, with hyaluronidase. The concentrations of Th cell-mediated cytokines , interleukin (IL)-4, IL-10, and interferon-, (IFN-,) , were measured in supernatants. The IL-4 production of PBMCs incubated with PHA/anti-CD28 mAb from children with repeated co-administration of glucocorticoids, hyaluronidase, and cytostatic drugs (median: 249.9 pg/ml; range: 234.4,261.7) was significantly higher (p < 0.0001) than IL-4 production of PBMC from children of all the other groups (median: 86.18; range: 16.0,212.5). There was no significant difference in the levels of IL-10 and IFN-, within the groups. PBMCs stimulated only with hyaluronidase failed to produce detectable levels of cytokines. The results of this study indicate that repeated co-administration of glucocorticoids and hyaluronidase (a neo-antigen) enhance IL-4 production in vitro and thus may induce the production of specific IgE antibodies in children immunocompromised with cytostatic drugs. Hyaluronidase itself does not stimulate in vitro IL-4 synthesis in PBMCs of children receiving cytostatic drugs. [source] Toxicity profile of delayed high dose sodium thiosulfate in children treated with carboplatin in conjunction with blood-brain-barrier disruption,PEDIATRIC BLOOD & CANCER, Issue 2 2006Edward A. Neuwelt MD Abstract Purpose To assess the safety of delayed high dose intravenous (i.v.) sodium thiosulfate (STS) in a case series of 12 children with malignant brain tumors who were treated with intraarterial (i.a.) carboplatin in conjunction with blood-brain-barrier disruption (BBBD). Methods Twelve children ages 17 months,12 years underwent a total of 132 BBBD chemotherapy treatments and also received delayed high dose STS (i.v.). Dose 1 of STS (10,16 g/m2) was administered 2 or 4 hr after carboplatin, and a second STS dose was administered 4 hr after dose 1 if the child had impaired baseline hearing. Toxicity data were graded in accordance with the National Cancer Institute Common Toxicity Criteria (Version 2). Audiologic monitoring to evaluate the otoprotective potential of STS was performed on 11 children. Ototoxicity was defined in accordance with the American Speech-Language-Hearing Association (ASHA) criteria. Baseline and end of treatment hearing status were graded using Brock's criteria. Results Nausea and vomiting were well controlled with anti-emetics administered approximately 30 min prior to STS infusion. Analogous to results in adult patients, there was mild transient hypernatremia and a trend for improved protection from ototoxicity in children who received STS delayed to 4 hr post-treatment versus 2 hr. Tumor responses were seen in heavily pre-treated patients with relatively chemo-resistant tumors, suggesting that STS did not protect the tumor from platinum cytotoxicity. Conclusion High dose STS is well tolerated in children under 12 years of age. Further studies of STS in children are warranted to assess otoprotection and the impact of STS on platinum mediated efficacy. © 2005 Wiley-Liss, Inc. [source] Chromosome 22q Deletions in Atypical Teratoid/Rhabdoid Tumors in AdultsBRAIN PATHOLOGY, Issue 1 2005Jack Raisanen MD Atypical teratoid/rhabdoid tumors (AT/RTs) are rare, malignant brain tumors that usually occur in the posterior fossa. Both AT/RT and the analogous tumor outside the brain, malignant rhabdoid tumor, share a polyphenotypic immunoprofile and frequent 22q deletions with inactivation of the INI1/hSNF5 gene. Reports, so far, indicate that AT/RTs occur almost exclusively in children, most of whom are 5-years-old or less. The rarity of the tumor and the polyphenotypic immunoprofile, characterized by antigen expression that is often patchy, make diagnosis in adults difficult and controversial. We describe three AT/RTs in adults in which the diagnoses were supported by detection of 22q11.2 deletions, INI1 mutation and/or loss of INI1 protein expression. Two patients were female, ages 20 and 31 and one was male, age 45. Two tumors occurred in the sella or sellar region and one in the cerebellum. In all cases, fluorescence in situ hybridization with probes to the BCR (22q11.2) and NF2 (22q12) regions of chromosome 22 revealed single copy deletions of BCR with normal dosages of NF2 and, in all cases, immunohistochemistry demonstrated loss of INI1 protein expression. In one case, a single base pair deletion was detected in the INI1/hSNF5 gene. These molecular findings confirm the occurrence of AT/RTs in adults. Although rare, AT/RT should be considered in the differential diagnosis of poorly differentiated intracranial tumors in adults. [source] High-dose chemotherapy with autologous stem cell rescue for children with recurrent malignant brain tumorsCANCER, Issue 6 2008Chie-Schin Shih MD Abstract BACKGROUND. High-dose chemotherapy (HDCT) with autologous stem cell rescue (ASCR) has been reported to be effective in treating children with recurrent central nervous system (CNS) malignancies. METHODS. To evaluate the efficacy and toxicities of HDCT and ASCR, the medical records of 27 children with recurrent CNS malignancies who received such therapy at St. Jude Children's Research Hospital between 1989 and 2004 were reviewed. RESULTS. The median age at diagnosis was 4.5 years (range, 0.4,16.6 years) and that at ASCR was 6.7 years (range, 1.1,18.5 years). Diagnoses included medulloblastoma (13 patients), primitive neuroectodermal tumor (3 patients), pineoblastoma (2 patients), atypical teratoid rhabdoid tumor (2 patients), ependymoma (3 patients), anaplastic astrocytoma (2 patients), and glioblastoma multiforme (2 patients). The 5-year overall and progression-free survival (PFS) rates were 28.2% and 18.5%, respectively. The 5-year PFS rate for patients aged <3 years at diagnosis (57.1%) was significantly better than older patients (5.0%) (P = .019). Among the 6 long-term survivors (5 with M0 disease and 1 with M3 disease at diagnosis), 5 received both radiotherapy and HDCT as part of their salvage regimen; 4 were aged <3 years at diagnosis and had received chemotherapy only as part of frontline therapy. Two patients died of transplant-related toxicities; 44% experienced grade 3 or 4 transplant-related toxicities (toxicities were graded according to the National Cancer Institute Common Toxicity Criteria). CONCLUSIONS. HDCT with ASCR is not an effective salvage strategy for older children with recurrent CNS malignancies. The significantly better outcome in the younger cohort was most likely related to the use of radiotherapy as part of the salvage strategy. Cancer 2008. © 2008 American Cancer Society. [source] | ||||||||||