In gliomas, the canonical Wingless/Int (WNT)/β-catenin pathway is increased while peroxisome proliferator-activated receptor gamma (PPAR-γ) is downregulated. The two systems act in an opposite manner. This review focuses on the interplay between WNT/β-catenin signaling and PPAR-γ and their metabolic implications as potential therapeutic target in gliomas. Activation of the WNT/β-catenin pathway stimulates the transcription of genes involved in proliferation, invasion, nucleotide synthesis, tumor growth, and angiogenesis. Activation of PPAR-γ agonists inhibits various signaling pathways such as the JAK/STAT, WNT/β-catenin, and PI3K/Akt pathways, which reduces tumor growth, cell proliferation, cell invasiveness, and angiogenesis. Nonsteroidal anti-inflammatory drugs, curcumin, antipsychotic drugs, adiponectin, and sulforaphane downregulate the WNT/β-catenin pathway through the upregulation of PPAR-γ and thus appear to provide an interesting therapeutic approach for gliomas. Temozolomide (TMZ) is an antiangiogenic agent. The downstream action of this opposite interplay may explain the TMZ-resistance often reported in gliomas.
Animals ; Brain Neoplasms ; metabolism ; therapy ; Dacarbazine ; analogs & derivatives ; pharmacology ; Down-Regulation ; drug effects ; Glioma ; metabolism ; therapy ; Humans ; PPAR gamma ; metabolism ; Temozolomide ; Wnt Signaling Pathway ; drug effects ; physiology

OBJECTIVETo observe the effect of RITA, a small molecule that targets p53, combined with temozolomide (TMZ) on proliferation, colony formation and apoptosis of human glioblastoma U87 cells and explore the underlying mechanism.

METHODSCultured U87 cells were treated with RITA (1, 5, 10, 20 µmol/L), TMZ, or RITA+TMZ (half dose) for 24, 48 or 72 h. MTS assay were used to detect the cell proliferation, and the cell proliferation rate and inhibitory rate were calculated. The effect of combined treatments was evaluated by the q value. The expressions of p53, p21 and other apoptosis-associated genes were detected by qRT-PCR and Western blotting; cell apoptosis was assayed using flow cytometry with Annexin V/PI double staining; colony formation of the cells was detected with crystal violet staining.

RESULTSMTS assay showed that RITA at the 4 doses more potently inhibited U87 cell viability than TMZ at 72 h (P=0.000) with inhibitory rates of 25.94%-41.38% and 3.84%-8.20%, respectively. RITA combined with TMZ caused a more significant inhibition of U87 cells (29.21%-52.11%) than RITA (P<0.01) and TMZ (P=0.000) alone. At the doses above 5 µmol/L, the combined treatments with RITA+TMZ for 48 h resulted in q values exceeding 1.2 and showed an obvious synergistic effect of the drugs. Both RITA and TMZ, especially the latter, significantly increased the expressions of p53, p21, puma, and other apoptosis-associated genes to accelerate apoptosis and inhibit the growth and colony formation of U87 cells, and the effect was more obvious with a combined treatment.

CONCLUSIONRITA inhibits the growth of human glioblastoma cells and enhance their sensitivity to TMZ by up-regulating p53 expression, and when combined, RITA and TMZ show a synergistic effect to cause a stronger cell inhibition.

Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; Dacarbazine ; analogs & derivatives ; pharmacology ; Furans ; pharmacology ; Glioblastoma ; drug therapy ; Humans

OBJECTIVE: To determine whether histogram values of the normalized apparent diffusion coefficient (nADC) and normalized cerebral blood volume (nCBV) maps obtained in contrast-enhancing lesions detected on immediate post-operative MR imaging can be used to predict the patient response to concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ). MATERIALS AND METHODS: Twenty-four patients with GBM who had shown measurable contrast enhancement on immediate post-operative MR imaging and had subsequently undergone CCRT with TMZ were retrospectively analyzed. The corresponding histogram parameters of nCBV and nADC maps for measurable contrast-enhancing lesions were calculated. Patient groups with progression (n = 11) and non-progression (n = 13) at one year after the operation were identified, and the histogram parameters were compared between the two groups. Receiver operating characteristic (ROC) analysis was used to determine the best cutoff value for predicting progression. Progression-free survival (PFS) was determined with the Kaplan-Meier method and the log-rank test. RESULTS: The 99th percentile of the cumulative nCBV histogram (nCBV C99) on immediate post-operative MR imaging was a significant predictor of one-year progression (p = 0.033). ROC analysis showed that the best cutoff value for predicting progression after CCRT was 5.537 (sensitivity and specificity were 72.7% and 76.9%, respectively). The patients with an nCBV C99 of < 5.537 had a significantly longer PFS than those with an nCBV C99 of ≥ 5.537 (p = 0.026). CONCLUSION: The nCBV C99 from the cumulative histogram analysis of the nCBV from immediate post-operative MR imaging may be feasible for predicting glioblastoma response to CCRT with TMZ.
Adult ; Aged ; Antineoplastic Agents, Alkylating/*therapeutic use ; Brain/pathology/radiography ; Brain Neoplasms/*drug therapy/mortality/radiography ; Chemoradiotherapy ; Dacarbazine/*analogs & derivatives/therapeutic use ; Diffusion Magnetic Resonance Imaging ; Disease Progression ; Disease-Free Survival ; Female ; Glioblastoma/*drug therapy/mortality/radiography ; Humans ; Kaplan-Meier Estimate ; Male ; Middle Aged ; Proportional Hazards Models ; ROC Curve ; Retrospective Studies

Although methyltransferase has been recognized as a major element that governs the epigenetic regulation of the genome during temozolomide (TMZ) chemotherapy in glioblastoma multiforme (GBM) patients, its regulatory effect on glioblastoma chemoresistance has not been well defined. This study investigated whether DNA methyltransferase (DNMT) expression was associated with TMZ sensitivity in glioma cells and elucidated the underlying mechanism. DNMT expression was analyzed by western blotting. miR-20a promoter methylation was evaluated by methylation-specific PCR. Cell viability and apoptosis were assessed using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and TdT-mediated dUTP-biotin nick end labeling assays, respectively. The results showed that compared with parental U251 cells, DNMT1 expression was downregulated, miR-20a promoter methylation was attenuated and miR-20a levels were elevated in TMZ-resistant U251 cells. Methyltransferase inhibition by 5-aza-2\'-deoxycytidine treatment reduced TMZ sensitivity in U251 cells. In U251/TM cells, DNMT1 expression was negatively correlated with miR-20a expression and positively correlated with TMZ sensitivity and leucine-rich repeats and immunoglobulin-like domains 1 expression; these effects were reversed by changes in miR-20a expression. DNMT1 overexpression induced an increase in U251/TM cell apoptosis that was inhibited by the miR-20a mimic, whereas DNMT1 silencing attenuated U251/TM cell apoptosis in a manner that was abrogated by miR-20a inhibitor treatment. Tumor growth of the U251/TM xenograft was inhibited by pcDNA-DNMT1 pretreatment and boosted by DNMT1-small hairpin RNA pretreatment. In summary, DNMT1 mediated chemosensitivity by reducing methylation of the microRNA-20a promoter in glioma cells.
Animals ; Antineoplastic Agents, Alkylating/*pharmacology/therapeutic use ; Apoptosis/drug effects ; Brain/drug effects/metabolism/pathology ; Brain Neoplasms/drug therapy/*genetics/pathology ; DNA (Cytosine-5-)-Methyltransferase/antagonists & inhibitors/*genetics/metabolism ; DNA Methylation ; Dacarbazine/*analogs & derivatives/pharmacology/therapeutic use ; Drug Resistance, Neoplasm ; Female ; Gene Expression Regulation, Neoplastic ; Glioma/drug therapy/*genetics/pathology ; Humans ; Mice, Inbred C57BL ; MicroRNAs/*genetics ; Promoter Regions, Genetic

OBJECTIVETo investigate programmed cell death induced by temozolomide in rat glioma C6 cell line.

METHODSRat glioma C6 cell line was treated by temozolomide at different concentrations and for different time lengths. MTT assay was used to evaluate the cell inhibition rate to determine the optimal exposure time and concentration. After the exposure to 400 µg/ml temozolomide for 24 h, the cells were observed for programmed cell death using HE staining, Hochest and Tunnel assay, Western blotting, and immunohistochemistry.

RESULTSMTT, HE staining, and Hochest and Tunnel assay all showed temozolomide-induced apoptosis in rat glioma C6 cell line. Western blotting and immunohistochemistry revealed up-regulation of Bax and down-regulation of Bcl-2 expression in the exposed cells, where the expressions of caspases 3, 8, 9, and 12 remained unchanged.

CONCLUSIONTemozolomide induces apoptosis in rat glioma C6 cell line through a caspase- independent pathway.

Animals ; Apoptosis ; Caspases ; Cell Line, Tumor ; Dacarbazine ; analogs & derivatives ; pharmacology ; Down-Regulation ; Glioma ; pathology ; Rats ; Up-Regulation

Based on reporting in the last several years, an impressive but dismal list of cytotoxic chemotherapies that fail to prolong the median overall survival of patients with glioblastoma has prompted the development of treatment protocols designed to interfere with growth-facilitating signaling systems by using non-cytotoxic, non-oncology drugs. Recent recognition of the pro-mobility stimulus, interleukin-18, as a driver of centrifugal glioblastoma cell migration allows potential treatment adjuncts with disulfiram and ritonavir. Disulfiram and ritonavir are well-tolerated, non-cytotoxic, non-oncology chemotherapeutic drugs that are marketed for the treatment of alcoholism and human immunodeficiency virus (HIV) infection, respectively. Both drugs exhibit an interleukin-18-inhibiting function. Given the favorable tolerability profile of disulfiram and ritonavir, the unlikely drug-drug interaction with temozolomide, and the poor prognosis of glioblastoma, trials of addition of disulfiram and ritonavir to current standard initial treatment of glioblastoma would be warranted.
Antineoplastic Agents ; Dacarbazine ; analogs & derivatives ; Disulfiram ; Glioblastoma ; Humans ; Interleukin-18 ; Ritonavir

This study was performed to validate the effectiveness and safety of concurrent chemoradiotherapy and adjuvant therapy with temozolomide for newly diagnosed glioblastoma multiforme as a standard treatment protocol. Between 2004 and 2011, patients newly diagnosed with glioblastoma who were treated with temozolomide during concurrent chemoradiotherapy and adjuvant chemotherapy were included from a single institution and analyzed retrospectively. The primary endpoint was overall survival, and the secondary endpoints were progression-free survival, response, and safety. A total of 71 patients were enrolled in this study. The response rate was 41% (29/71), and the tumor control rate was 80% (57/71). In the 67 patients who completed the concurrent chemoradiotherapy with temozolomide, the median overall survival was 19 months and the 1- and 2-yr overall survival rates were 78.3% and 41.7%, respectively. The median progression free survival was 9 months, and the 1- and 2-yr progression free survival rates were 33.8% and 14.3%, respectively. The mean duration of survival after progression of disease in salvage treatment group was 11.9 (1.3-53.2) months. Concurrent chemoradiotherapy with temozolomide resulted in grade 3 or 4 hematologic toxic effects in 2.8% of the patients. The current protocol of temozolomide during and after radiation therapy is both effective and safe and is still appropriate as the standard protocol for treatment of glioblastoma. An active salvage treatment might be required for a better prognosis.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Antineoplastic Agents, Alkylating/administration & dosage ; Brain Neoplasms/diagnosis/*mortality/*therapy ; Chemoradiotherapy, Adjuvant/methods/mortality ; Comorbidity ; Dacarbazine/administration & dosage/*analogs & derivatives ; Female ; Glioblastoma/diagnosis/*mortality/*therapy ; Hematologic Diseases/*mortality ; Humans ; Longitudinal Studies ; Male ; Middle Aged ; Prevalence ; Radiotherapy, Conformal/mortality ; Republic of Korea/epidemiology ; Risk Factors ; Survival Rate ; Treatment Outcome ; Young Adult

BACKGROUNDThe radiochemotherapy regimen concomitantly employing temozolomide (TMZ) chemotherapy and radiotherapy (RT) 4 weeks after surgery, followed by 6 cycles of TMZ is a common treatment for glioblastoma (GBM). However, its median overall survival (OS) is only 14.6 months. This study was to explore the effectiveness and safety of early TMZ chemotherapy between surgery and chemoradiotherapy plus the standard concomitant radiochemotherapy regimen.

METHODSA randomized, parallel group, open-label study of 99 newly diagnosed GBM patients was conducted at 10 independent Chinese neurosurgical departments from June 2008 to June 2012. Patients were treated with concomitant radiochemotherapy regimen plus early postsurgical temozolomide (early TMZ group) or standard concomitant radiochemotherapy regimen (control group). Overall response was assessed based on objective tumor assessments, administration of corticosteroid and neurological status test. Hematological, biochemical, laboratory, adverse event (AE), and neurological condition were measured for 24 months of follow-up. The primary efficacy endpoint of this study was overall survival (OS). The secondary endpoint was progression free survival (PFS).

RESULTSThe median OS time in the early TMZ group was 17.6 months, compared with 13.2 months in the control group (log-rank test P = 0.021). In addition, the OS rate in the early TMZ group was higher at 6, 12, and 18 months than in the control group, respectively (P < 0.05). The median PFS time was 8.7 months in the early TMZ group and 10.4 months in the control group (log-rank test P = 0.695). AEs occurred in 29 (55.8%) and 31(73.8%) patients respectively in early and control groups, including nausea (15.4% vs. 33.3%), vomiting (7.7% vs. 28.6%), fever (7.7% vs. 11.9%), and headache (3.8% vs. 23.8%). Only 30.8% and 33.3% were drug-related, respectively.

CONCLUSIONSAddition of TMZ chemotherapy in the early break of the standard concomitant radiochemotherapy regimen was well tolerated and significantly improved the OS of the GBM patients, compared with standard concomitant radiochemotherapy regimen. However, a larger randomized trial is warranted to verify these results.

Adult ; Aged ; Antineoplastic Agents, Alkylating ; therapeutic use ; Chemoradiotherapy ; methods ; Dacarbazine ; analogs & derivatives ; therapeutic use ; Glioblastoma ; drug therapy ; radiotherapy ; Humans ; Middle Aged ; Treatment Outcome ; Young Adult

OBJECTIVETo study the therapeutic effect of intranasal administration of temozolomide (TMZ) for brain-targeting delivery in a rat model bearing orthotopic C6 glioma xenografts.

METHODSForty Wistar rat bearing brain C6 glioma xenograft were randomly divided into 4 groups and treated with physiological saline solution or with TMZ by intravenous injection, gavage or intranasal administration. The tumor size, rat survival time and pathological changes were observed in each group.

RESULTSMagnetic resonance imaging showed a significantly reduced volume of glioma in intranasal TMZ group compared with that in the control, intraveneous TMZ injection group and TMZ gavage groups (12.45∓2.49 mm(3) vs 60.16∓4.12, 33.17∓3.56, and 35.16∓4.36 mm(3), respectively, P<0.05). The median survival time of the C6 glioma-bearing rats was also significantly longer in intranasal TMZ group than in the other 3 groups (31.0 days vs 20, 19, and 21.5 days, respectively, P<0.05). In the glioma xenografts, PCNA expression was the lowest and tumor cell apoptosis rate the highest in intranasal TMZ group.

CONCLUSIONIntranasal TMZ administration can suppress the growth of C6 glioma in rats and may serve as an effective strategy for glioma treatment.

Administration, Intranasal ; Animals ; Antineoplastic Agents, Alkylating ; administration & dosage ; Apoptosis ; Brain Neoplasms ; drug therapy ; Cell Line, Tumor ; Dacarbazine ; administration & dosage ; analogs & derivatives ; Drug Delivery Systems ; Glioma ; drug therapy ; Magnetic Resonance Imaging ; Neoplasm Transplantation ; Rats ; Rats, Wistar

The current standards in radiotherapy of high-grade gliomas (HGG) are based on anatomic imaging techniques, usually computed tomography (CT) scanning and magnetic resonance imaging (MRI). The guidelines vary depending on whether the HGG is a histological grade 3 anaplastic glioma (AG) or a grade 4 glioblastoma multiforme (GBM). For AG, T2-weighted MRI sequences plus the region of contrast enhancement in T1 are considered for the delineation of the gross tumor volume (GTV), and an isotropic expansion of 15 to 20 mm is recommended for the clinical target volume (CTV). For GBM, the Radiation Therapy Oncology Group favors a two-step technique, with an initial phase (CTV1) including any T2 hyperintensity area (edema) plus a 20 mm margin treated with up to 46 Gy in 23 fractions, followed by a reduction in CTV2 to the contrast enhancement region in T1 with an additional 25 mm margin. The European Organisation of Research and Treatment of Cancer recommends a single-phase technique with a unique GTV, which comprises the T1 contrast enhancement region plus a margin of 20 to 30 mm. A total dose of 60 Gy in 30 fractions is usually delivered for GBM, and a dose of 59.4 Gy in 33 fractions is typically given for AG. As more than 85% of HGGs recur in field, dose-escalation studies have shown that 70 to 75 Gy can be delivered in 6 weeks with relevant toxicities developing in <10% of the patients. However, the only randomized dose-escalation trial, in which the boost dose was guided by conventional MRI, did not show any survival advantage of this treatment over the reference arm. HGGs are amongst the most infiltrative and heterogeneous tumors, and it was hypothesized that the most highly aggressive areas were missed; thus, better visualization of these high-risk regions for radiation boost could decrease the recurrence rate. Innovations in imaging and linear accelerators (LINAC) could help deliver the right doses of radiation to the right subvolumes according to the dose-painting concept. Advanced imaging techniques provide functional information on cellular density (diffusion MRI), angiogenesis (perfusion MRI), metabolic activity and cellular proliferation [positron emission tomography (PET) and magnetic resonance spectroscopy (MRS)]. All of these non-invasive techniques demonstrated good association between the images and histology, with up to 40% of HGGs functionally presenting a high activity within the non-contrast-enhanced areas in T1. New LINAC technologies, such as intensity-modulated and stereotactic radiotherapy, help to deliver a simultaneous integrated boost (SIB) > 60 Gy. Trials delivering a SIB into a biological GTV showed the feasibility of this treatment, but the final results, in terms of clinical benefits for HGG patients, are still pending. Many issues have been identified: the variety of MRI and PET machines (and amino-acid tracers), the heterogeneity of the protocols used for image acquisition and post-treatment, the geometric distortion and the unreliable algorithms for co-registration of brain anatomy with functional maps, and the semi-quiescent but highly invasive HGG cells. These issues could be solved by the homogenization of the protocols and software applications, the simultaneous acquisition of anatomic and functional images (PET-MRI machines), the combination of complementary imaging tools (perfusion and diffusion MRI), and the concomitant addition of some ad hoc targeted drugs against angiogenesis and invasiveness to chemoradiotherapy. The integration of these hybrid data will construct new synthetic metrics for fully individualized treatments.
Antineoplastic Agents, Alkylating ; therapeutic use ; Brain Neoplasms ; diagnosis ; pathology ; radiotherapy ; Dacarbazine ; analogs & derivatives ; therapeutic use ; Diffusion Tensor Imaging ; Glioblastoma ; diagnosis ; drug therapy ; pathology ; radiotherapy ; Glioma ; diagnosis ; pathology ; radiotherapy ; Humans ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; Neoplasm Grading ; Particle Accelerators ; Positron-Emission Tomography ; Radiotherapy Dosage ; Radiotherapy, Intensity-Modulated ; methods