Malignant gliomas are the most common and deadly primary brain tumors in adults. Increasing evidence has indicated that microRNAs (miRNAs) have an influence on the regulation of apoptotic cell signaling. Downregulation of miRNA 218 (miR-218) has been indicated in human glioma specimens. Here, we investigate the function of miR-218 in apoptosis and tumor growth of glioma cells.
The expression of miR-218 was detected by real-time quantitative reverse transcriptase PCR. The effects of miR-218 on glioma cell proliferation and tumorigenicity were investigated by in vitro clonogenicity and in vivo xenograft assay. Apoptosis was evaluated by flow cytometric analysis and assay by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling. The downstream targets of miR-218 were identified by bioinformatics analysis and further validated by Western blot and luciferase reporter assay.
Overexpression of miR-218 induces glioma cell apoptosis and inhibits glioma cell viability, proliferation, and tumorigenicity. Epidermal growth factor receptor–coamplified and overexpressed protein (ECOP) was identified as a functional downstream target of miR-218, which can regulate transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and associated with apoptotic response. Ectopic expression of ECOP rescued the glioma cells from miR-218–induced apoptosis and increased NF-κB activity.
These results suggest that miR-218 sensitizes glioma cells to apoptosis by regulating ECOP-mediated suppression of NF-κB activity, which may provide novel opportunities for glioma therapy.
apoptosis; ECOP; glioma; miR-218; NF-κB
Spinal astrocytomas are rare intramedullary CNS tumors for which there is limited consensus on treatment; the importance of the extent of resection (EOR), postoperative radiotherapy, and chemotherapy remains poorly understood. We report on outcomes associated with surgery, postoperative radiotherapy, and chemotherapy in a series of patients treated at M. D. Anderson Cancer Center (MDACC) with the aim of elucidating the role of these treatments in spinal astrocytomas.
We retrospectively reviewed charts from a series of 83 patients with histologically confirmed spinal astrocytoma treated at MDACC during 1990–2011. Data collected included patient demographic characteristics, prognostic indicators, and treatment modality at diagnosis. We analyzed overall survival (OS) and progression-free survival (PFS) for pilocytic (World Health Organization [WHO] grade I) and infiltrative (WHO grades II, III, and IV) astrocytomas, separately. Multivariate analysis was performed for the infiltrative patients but not the pilocytic patients because of a limited number of cases.
Higher WHO grade among all patients was associated with worse OS (P < .0001) and PFS (P = .0003). Among patients with infiltrative tumors, neither EOR nor radiotherapy was associated with a difference in outcomes in multivariate analysis; however, among patients with infiltrative astrocytomas, chemotherapy was significantly associated with improved PFS (hazard ratio = .22, P = .0075) but not OS (hazard ratio = .89, P = .83) in multivariate analysis.
WHO grade was the strongest prognostic indicator in patients with spinal cord astrocytomas. Our results also show that chemotherapy improved PFS in infiltrative astrocytomas in multivariate analysis, but neither EOR nor radiation therapy influenced outcomes in this group.
chemotherapy; glioma; intramedullary; management prognosis
Low-grade gliomas (LGGs) are rare brain neoplasms, with survival spanning up to a few decades. Thus, accurate evaluations on how biomarkers impact survival among patients with LGG require long-term studies on samples prospectively collected over a long period.
The 210 adult LGGs collected in our databank were screened for IDH1 and IDH2 mutations (IDHmut), MGMT gene promoter methylation (MGMTmet), 1p/19q loss of heterozygosity (1p19qloh), and nuclear TP53 immunopositivity (TP53pos). Multivariate survival analyses with multiple imputation of missing data were performed using either histopathology or molecular markers. Both models were compared using Akaike's information criterion (AIC). The molecular model was reduced by stepwise model selection to filter out the most critical predictors. A third model was generated to assess for various marker combinations.
Molecular parameters were better survival predictors than histology (ΔAIC = 12.5, P< .001). Forty-five percent of studied patients died. MGMTmet was positively associated with IDHmut (P< .001). In the molecular model with marker combinations, IDHmut/MGMTmet combined status had a favorable impact on overall survival, compared with IDHwt (hazard ratio [HR] = 0.33, P< .01), and even more so the triple combination, IDHmut/MGMTmet/1p19qloh (HR = 0.18, P< .001). Furthermore, IDHmut/MGMTmet/TP53pos triple combination was a significant risk factor for malignant transformation (HR = 2.75, P< .05).
By integrating networks of activated molecular glioma pathways, the model based on genotype better predicts prognosis than histology and, therefore, provides a more reliable tool for standardizing future treatment strategies.
biomarker; brain tumor; cancer pathways; prognosis
The metabolic phenotype that derives disproportionate energy via glycolysis in solid tumors, including glioma, leads to elevated lactate labeling in metabolic imaging using hyperpolarized [1-13C]pyruvate. Although the pyruvate dehydrogenase (PDH)–mediated flux from pyruvate to acetyl coenzyme A can be indirectly measured through the detection of carbon-13 (13C)-labeled bicarbonate, it has proven difficult to visualize 13C-bicarbonate at high enough levels from injected [1-13C]pyruvate for quantitative analysis in brain. The aim of this study is to improve the detection of 13C-labeled metabolites, in particular bicarbonate, in glioma and normal brain in vivo and to measure the metabolic response to dichloroacetate, which upregulates PDH activity.
An optimized protocol for chemical shift imaging and high concentration of hyperpolarized [1-13C]pyruvate were used to improve measurements of lactate and bicarbonate in C6 glioma-transplanted rat brains. Hyperpolarized [1-13C]pyruvate was injected before and 45 min after dichloroacetate infusion. Metabolite ratios of lactate to bicarbonate were calculated to provide improved metrics for characterizing tumor metabolism.
Glioma and normal brain were well differentiated by lactate-to-bicarbonate ratio (P = .002, n = 5) as well as bicarbonate (P = .0002) and lactate (P = .001), and a stronger response to dichloroacetate was observed in glioma than in normal brain.
Our results clearly demonstrate for the first time the feasibility of quantitatively detecting 13C-bicarbonate in tumor-bearing rat brain in vivo, permitting the measurement of dichloroacetate-modulated changes in PDH flux. The simultaneous detection of lactate and bicarbonate provides a tool for a more comprehensive analysis of glioma metabolism and the assessment of metabolic agents as anti-brain cancer drugs.
bicarbonate; dichloroacetate; glioma; hyperpolarized 13C; pyruvate
Apathy is associated with pervasive and disadvantageous effects on daily functioning. It has been observed transiently in some children after surgery for posterior fossa tumors. In this study, our objective was to examine prevalence, associations, and predictors of apathy in adult survivors of an infantile posterior fossa brain tumor (PFT).
One hundred seventeen adult survivors of a childhood PFT diagnosed before age 5 years and 60 of their siblings were assessed in a cross-sectional study a mean of 32 years (range, 18–53 years) after survivors' initial tumor diagnoses, using the Marin Apathy Evaluation Scale (AES), the Weschler Abbreviated Scale of Intelligence and the Composite International Diagnostic Interview for psychiatric disorders.
Marin Apathy Evaluation Scale, the Weschler Abbreviated Scale of Intelligence reached or exceeded a criterion score for clinically significant apathy in 35% of survivors, compared with 18% in a sibling comparison group. In both siblings and survivors, apathy was associated with lower verbal and full-scale IQ and, among survivors, with having undergone partial rather than total tumor resection (independent of irradiation status). Apathy was not related to presence of concurrent International Classification of Diseases, 10th Revision, depression. Female sex was associated with late apathy after a PFT, with increased likelihood of women reaching the apathy criterion relative to men if they were survivors.
Clinically significant and potentially treatable apathy occurs relatively commonly in adult survivors of an infantile childhood PFT, particularly women. Clinicians, including those managing posterior fossa pathology in very young children, should be aware of this association, and future research should clarify whether specific treatment-related variables are implicated in increasing this risk of apathy.
apathy; cancer; cerebellum; cognitive; infancy; radiotherapy; survivorship
Fluorine-18 (18F) fluorodeoxyglucose (FDG) positron emission tomography (PET) is limited in its evaluation of brain tumors due to the high basal activity of the cerebral cortex and white matter. Carbon-11 methionine (11C MET) has little uptake under normal conditions. We prospectively investigated the uptake of 18F FDG and 11C MET PET in patients with craniopharyngioma prior to proton therapy.
Ten patients newly diagnosed with craniopharyngioma underwent PET imaging using 18F FDG and 11C MET. PET and MRI studies were registered to help identify tumor volume. Measurements of maximum standardized uptake value (SUVmax) were taken of the tumor and compared with noninvolved left frontal background white matter using a paired t-test. Uptake was graded using a 4-point scale.
Median patient age was 9 years (range 5–19). Seven patients were diagnosed by pathology, 1 by cyst fluid aspiration, and 2 by neuroimaging. Median FDG SUVmax for tumor and background were 2.65 and 3.2, respectively. Median MET SUVmax for tumor and background were 2.2 and 1, respectively. There was a significant difference between MET tumor SUVmax and MET background SUVmax (P = .0001). The difference between FDG tumor SUVmax and FDG background SUVmax was not significant (P = .3672).
11C MET PET uptake is significantly greater within the tumor compared with noninvolved background white matter, making it more useful than FDG PET in identifying active tumor in patients with craniopharyngioma. Future work will focus on using 11C MET PET to discriminate between active and inactive tumor after irradiation.
craniopharyngioma; fluorodeoxyglucose; FDG; methionine; positron emission tomography; proton therapy
The signal transduction pathways of epidermal growth factor receptor and Ras are both important in the growth of glioblastoma multiforme (GBM). We hypothesized that inhibition of both pathways would improve the survival time of patients with recurrent GBM.
Patients with recurrent/progressive GBM with 0–2 prior chemotherapy regimens received erlotinib 150 mg once daily and sorafenib 400 mg twice daily until progression. The primary endpoint was overall survival. Pharmacokinetic sampling was performed during cycle 1.
The median overall survival was 5.7 months. Progression-free survival at 6 months was 14%. Toxicity was manageable. Clearance of erlotinib was markedly enhanced by sorafenib.
The study did not meet its objective of a 30% increase in overall survival time compared with historical controls. Erlotinib and sorafenib have significant pharmacokinetic interactions that may negatively impact the efficacy of the combination regimen.
EGFR; erlotinib; pharmacokinetics; glioblastoma; Ras signaling; sorafenib; targeted therapy
Standard pre- and postcontrast (T1 + C) anatomical MR imaging is proving to be insufficient for accurately monitoring bevacizumab treatment response in recurrent glioblastoma (GBM). We present a novel imaging biomarker that detects abnormal tumor vasculature exhibiting both arterial and venous perfusion characteristics. We hypothesized that a decrease in the extent of this abnormal vasculature after bevacizumab treatment would predict treatment efficacy and overall survival.
Dynamic susceptibility contrast perfusion MRI was gathered in 43 patients with high-grade glioma. Independent component analysis separated vasculature into arterial and venous components. Voxels with perfusion characteristics of both arteries and veins (ie, arterio-venous overlap [AVOL]) were measured in patients with de novo untreated GBM and patients with recurrent high-grade glioma before and after bevacizumab treatment. Treated patients were separated on the basis of an increase or decrease in AVOL volume (+/−ΔAVOL), and overall survival following bevacizumab onset was then compared between +/−ΔAVOL groups.
AVOL in untreated GBM was significantly higher than in normal vasculature (P < .001). Kaplan-Meier survival curves revealed a greater median survival (348 days) in patients with GBM with a negative ΔAVOL after bevacizumab treatment than in patients with a positive change (197 days; hazard ratio, 2.51; P < .05). Analysis of patients with combined grade III and IV glioma showed similar results, with median survivals of 399 days and 153 days, respectively (hazard ratio, 2.71; P < .01). Changes in T1+C volume and ΔrCBV after treatment were not significantly different across +/−ΔAVOL groups, and ΔAVOL was not significantly correlated with ΔT1+C or ΔrCBV.
The independent component analysis dynamic susceptibility contrast–derived biomarker AVOL adds additional information for determining bevacizumab treatment efficacy.
angiogenesis; bevacizumab; brain tumor; DSC; glioblastoma; glioma; perfusion; ICA; independent component analysis; MRI
The goal of this study was to investigate whether the amount of hypointense signal on susceptibility-weighted imaging within the contrast-enhancing lesion (%SWI-h) on the pretreatment scan could determine response in patients with newly diagnosed glioblastoma multiforme who received external beam radiation therapy with concomitant anti-angiogenic therapy (enzastaurin) and cytotoxic chemotherapy (temozolomide).
Twenty-five patients were imaged before therapy (postsurgical resection) and scanned serially every 2 months until progression. Standard clinical MR imaging and SWI were performed on a 3T scanner. %SWI-h was quantified for each patient's pretreatment scan. Time to progression and death were used to characterize patients into non-, immediate-, and sustained-response groups for both events. Cox proportional hazards models were used to assess the association between %SWI-h and both progression-free survival (PFS) and overall survival (OS). Classification and regression tree analysis were used to determine optimal cutoffs on which to split %SWI-h.
For both death- and progression-based response categories, %SWI-h was significantly higher in sustained responders than in nonresponders. Cox model coefficients showed an association between %SWI-h and PFS and OS, both in univariate analysis (PFS: hazard ratio [HR] = 0.966, 95% confidence interval [CI] = 0.942–0.988; and OS: HR = 0.945, 95% CI = 0.915–0.976) and when adjusting for baseline KPS, age, sex, and resection extent (PFS: HR = 0.968, 95% CI = 0.940 –0.994; and OS: HR = 0.943, 95% CI = 0.908 –0.976). A cutoff value of 38.1% significantly differentiated patients into 2 groups based on censored OS and into non- and intermediate-response categories based on time to progression.
These early differences suggest that SWI may be able to predict which patients would benefit most from similar combination therapies and may assist clinicians in making important decisions about patient care.
glioma; response to anti-angiogenic therapy; susceptibility-weighted imaging
Secreted protein acidic and rich in cysteine (SPARC) is overexpressed in astrocytomas (World Health Organization grades II–IV). We previously demonstrated that SPARC promotes glioma migration and invasion—in part, by activating the P38 mitogen-activated protein kinase (MAPK)–heat shock protein (HSP)27 signaling pathway. The commonly lost tumor suppressor phosphatase and tensin homolog (PTEN) suppresses SPARC-induced migration, which is accompanied by suppression of Shc-Ras-Raf-MEK-ERK1/2 and Akt signaling. As PTEN completely suppresses SPARC-induced migration, we proposed that PTEN must also interfere with SPARC-induced HSP27 signaling. Therefore, this study determined the effects of PTEN expression on SPARC-induced expression and phosphorylation of HSP27.
Control and SPARC-expressing clones transfected with control- or PTEN-expression plasmids were plated on fibronectin-coated tissue culture plates for 3, 6, 24, and 48 h and then lysed. Equal amounts of protein were subjected to Western blot and densitometric analyses.
The results show that SPARC enhances phosphorylated (p)P38 MAPK, phosphorylated MAPK-activated protein kinase 2 (pMAPKAPK2), and serine (Ser)78 HSP27 phosphorylation relative to total HSP27. PTEN suppresses pAkt and pMAPKAPK2, suggesting that PTEN effects are downstream of pP38 MAPK. PTEN suppressed SPARC-induced sustained phosphorylation at Ser78 HSP27. As the level of total HSP27 differed based on the presence of SPARC or PTEN, the ratios of phosphorylation-specific to total HSP27 were examined. The data demonstrate that SPARC-induced phosphorylation at Ser78 remains elevated despite increasing levels of total HSP27. In contrast, PTEN inhibits SPARC-induced increases in Ser78 HSP27 phosphorylation relative to total HSP27.
These data describe a novel mechanism whereby PTEN inhibits SPARC-induced migration through suppression and differential regulation of pAkt and the P38 MAPK-MAPKAPK2-HSP27 signaling pathway.
gliomas; SPARC; PTEN; HSP27; signaling
Glioblastoma multiforme (GBM) is a heterogeneous, highly aggressive primary brain tumor with strongly variable patient survival. Because reliable prognostic biomarkers are lacking, we investigated the relation between telomerase-associated parameters and the disease course.
Telomerase-associated parameters were determined in 100 GBM tissues and associated with clinical characteristics and overall survival. Expressions of telomere length, telomerase activity (TA), and human telomerase reverse transcriptase (hTERT) were analyzed by quantitative PCR, telomeric repeat amplification protocol assay, and reverse transcriptase–PCR, respectively. Mutation status of isocitrate dehydrogenase (IDH)1 was determined by direct sequencing, and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation by methylation-specific PCR.
Of 100 GBM tissues, 61 were positive for both hTERT mRNA and TA, with a highly significant correlation between both parameters (linear regression, P < .0001). Telomere length determination revealed a significant difference between the hTERT/TA-positive and -negative subgroups, with markedly longer telomeres in the hTERT/TA-negative cohort (unpaired Student's t-test, P = .0001). Accordingly, significantly shorter telomeres were detected in GBM tissues derived from older patients (>60 y at diagnosis, P < .0001). While no association of telomere parameters with MGMT promoter status was found, all tumors with IDH1 mutation (6/100) were negative for both hTERT expression and TA and harbored significantly longer telomeres. Patients with tumors lacking hTERT expression/TA showed a significant survival benefit (Kaplan–Meier test, both P < .01), which, however, was based exclusively on the younger patient subgroup (≤60 y, both P < .005; >60 y, both ns).
Telomerase activation is not an independent prognostic parameter in GBM but predicts aggressive tumor behavior solely in a younger patient cohort.
telomerase; glioblastoma; age; prognosis; survival
Astrocytic tumors account for 42% of childhood brain tumors, arising in all anatomical regions and associated with neurofibromatosis type 1 (NF1) in 15%. Anatomical site determines the degree and risk of resectability; the more complete resection, the better the survival rates. New biological markers and modern radiotherapy techniques are altering the risk assessments of clinical decisions for tumor resection and biopsy. The increasingly distinct pediatric neuro-oncology multidisciplinary team (PNMDT) is developing a distinct evidence base.
A multidisciplinary consensus conference on pediatric neurosurgery was held in February 2011, where 92 invited participants reviewed evidence for clinical management of hypothalamic chiasmatic glioma (HCLGG), diffuse intrinsic pontine glioma (DIPG), and high-grade glioma (HGG). Twenty-seven statements were drafted and subjected to online Delphi consensus voting by participants, seeking >70% agreement from >60% of respondents; where <70% consensus occurred, the statement was modified and resubmitted for voting.
Twenty-seven statements meeting consensus criteria are reported. For HCLGG, statements describing overall therapeutic purpose and indications for biopsy, observation, or treatment aimed at limiting the risk of visual damage and the need for on-going clinical trials were made. Primary surgical resection was not recommended. For DIPG, biopsy was recommended to ascertain biological characteristics to enhance understanding and targeting of treatments, especially in clinical trials. For HGG, biopsy is essential, the World Health Organization classification was recommended; selection of surgical strategy to achieve gross total resection in a single or multistep process should be discussed with the PNMDT and integrated with trials based drug strategies for adjuvant therapies.