Longitudinal Trajectories of Post-Concussive Symptoms Following Mild Traumatic Brain Injury.

BACKGROUND: Individuals recovering from mild traumatic brain injury (TBI) represent a heterogenous population that requires distinct treatment approaches. Identification of recovery trajectories improves our ability to understand the natural history of mild TBI recovery and develop targeted interventions. OBJECTIVE: To utilize group-based trajectory modeling (GBTM) to identify distinct patterns of symptom recovery following mild TBI in the first 6 months after mild TBI. METHODS: This study is comprised of 253 adults who presented to the emergency department with mild TBI and completed assessments for six-months post-injury. Patients were recruited for the prospective observational cohort study, HeadSMART. The primary outcome measure was the Rivermead Postconcussion Symptom Questionnaire. GBTM was used to identify longitudinal trajectories of recovery following mild TBI using Rivermead scores at baseline, one, three, and six months following diagnosis. RESULTS: Findings identified four distinct trajectories of symptom recovery follwing mild TBI including 9% of participants who were categorized with minimal acute symptoms that decreased over time, 45% with mild acute symptoms that decreased over time, 33% with relatively higher acute symptoms that decreased over time, and 13% with relatively higher acute symptoms that increased over time. CONCLUSIONS: GBTM identified four distinct trajectories of recovery following mild TBI and GBTM may be useful for research interventions that can alter recovery trajectories.

Prevalence and Correlates of Depressive Symptoms Within 6 Months After First-Time Mild Traumatic Brain Injury.

OBJECTIVE: Depressive symptoms are among the most common neuropsychiatric sequelae of mild traumatic brain injury (mTBI). Very few studies have compared correlates of depressive symptoms within the first 6 months of injury in cohorts experiencing their first TBI. The authors investigated whether the correlates of depressive symptoms (being female, older, lower education, having brain lesions, experiencing worse postconcussive symptoms, and incomplete functional recovery) that have been established in populations with moderate to severe TBI were the same for individuals with first-time mTBI within the first 6 months of recovery. METHODS: Two hundred seventeen individuals with first-time mTBI were divided into subgroups-new-onset depressive symptoms, recurrent depressive symptoms, prior depression history only, and never depressed-and compared on clinical and demographic variables and the presence of postconcussive symptoms and functional recovery at 3 and 6 months. RESULTS: New-onset depressive symptoms developed in 12% of the cohort, whereas 11% of the cohort had recurrent depressive symptoms. Both depressive symptoms groups were more likely to comprise women and persons of color and were at higher risk for clinically significant postconcussive symptoms and incomplete functional recovery for the first 6 months postinjury. CONCLUSIONS: Presence of depressive symptoms after first-time mTBI was associated with persistent postconcussive symptoms and incomplete functional recovery in the first 6 months. Adding to the existing literature, these findings identified correlates of depressive symptom development and poor outcomes after mTBI, thus providing further evidence that mTBI may produce persistent symptoms and functional limitations that warrant clinical attention.

A Prognostic Model for Predicting One-Month Outcomes among Emergency Department Patients with Mild Traumatic Brain Injury and a Presenting Glasgow Coma Scale of Fifteen.

The lack of well-performing prognostic models for early prognostication of outcomes remains a major barrier to improving the clinical care of patients with mild traumatic brain injury (mTBI). We aimed to derive a prognostic model for predicting incomplete recovery at 1-month in emergency department (ED) patients with mTBI and a presenting Glasgow Coma Scale (GCS) score of 15 who were enrolled in the HeadSMART (Head Injury Serum Markers for Assessing Response to Trauma) study. The derivation cohort included 355 participants with complete baseline (day-of-injury) and follow-up data. The primary outcome measure was the Glasgow Outcome Scale Extended (GOSE) at 1-month and incomplete recovery was defined as a GOSE <8. At 1-month post-injury, incomplete recovery was present in 58% (n = 205) of participants. The final multi-variable logistic regression model included six variables: age in years (odds ratio [OR] = 0.98; 95% confidence interval [CI]: 0.97-1.00), positive head CT (OR = 4.42; 95% CI: 2.21-9.33), history of depression (OR = 2.59; 95% CI: 1.47-4.69), and self-report of moderate or severe headache (OR = 2.49; 95% CI: 1.49-4.18), difficulty concentrating (OR = 3.17; 95% CI: 1.53-7.04), and photophobia (OR = 4.17; 95% CI: 2.08-8.92) on the day-of-injury. The model was validated internally using bootstrap resampling (1000 resamples), which revealed a mean over-optimism value of 0.01 and an optimism-corrected area under the curve (AUC) of 0.79 (95% CI: 0.75-0.85). A prognostic model for predicting incomplete recovery among ED patients with mTBI and a presenting GCS of 15 using easily obtainable clinical and demographic variables has acceptable discriminative accuracy. External validation of this model is warranted.

Age differences in outcome after mild traumatic brain injury: results from the HeadSMART study.

This study longitudinally examined age differences across multiple outcome domains in individuals diagnosed with acute mild traumatic brain injury (mTBI). A sample of 447 adults meeting VA/DoD criteria for mTBI was dichotomized by age into older (≥65 years; n = 88) and younger (<65 years; n = 359) sub-groups. All participants presented to the emergency department within 24 hours of sustaining a head injury, and outcomes were assessed at 1-, 3-, and 6-month intervals. Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9), post-concussive symptoms (PCS) were ascertained with the Rivermead Post-Concussion Questionnaire (RPQ), and functional recovery from the Extended Glasgow Outcome Scale (GOSE). Mixed effects logistic regression models showed that the rate of change over time in odds of functional improvement and symptom alleviation did not significantly differ between age groups (p = 0.200-0.088). Contrary to expectation, older adults showed equivalent outcome trajectories to younger persons across time. This is a compelling finding when viewed in light of the majority opinion that older adults are at risk for significantly worse outcomes. Future work is needed to identify the protective factors inherent to sub-groups of older individuals such as this.

A C19MC-LIN28A-MYCN Oncogenic Circuit Driven by Hijacked Super-enhancers Is a Distinct Therapeutic Vulnerability in ETMRs: A Lethal Brain Tumor.

Embryonal tumors with multilayered rosettes (ETMRs) are highly lethal infant brain cancers with characteristic amplification of Chr19q13.41 miRNA cluster (C19MC) and enrichment of pluripotency factor LIN28A. Here we investigated C19MC oncogenic mechanisms and discovered a C19MC-LIN28A-MYCN circuit fueled by multiple complex regulatory loops including an MYCN core transcriptional network and super-enhancers resulting from long-range MYCN DNA interactions and C19MC gene fusions. Our data show that this powerful oncogenic circuit, which entraps an early neural lineage network, is potently abrogated by bromodomain inhibitor JQ1, leading to ETMR cell death.

Loss of consciousness and altered mental state predicting depressive and post-concussive symptoms after mild traumatic brain injury.

Objective: Limited studies exist on the association between loss of consciousness (LOC) and altered mental state (AMS) and development of depressive and post-concussive symptoms within six months after mild traumatic brain injury (mTBI). We tested the hypothesis that presence of both LOC and AMS predict the highest risk of symptoms within the first six months post-mTBI compared to either variable alone, and that LOC alone is more strongly associated with these symptoms. Research design: We analyzed data from 407 subjects with mTBI from the Head injury Serum Markers for Assessing Response to Trauma (HeadSMART) cohort, a prospective cohort of patients post-TBI presenting to two urban emergency departments. Results: There were higher rates of depressive (44%) and post-concussive symptoms (54%) at 1 month post-injury, among participants with both LOC and AMS compared to other groups. AMS was associated with depressive symptoms at one and six months (OR = 1.59, p = .038; OR = 1.60; p = .060) and post-concussive symptoms at one month (OR = 1.56, p = .053). LOC was associated only with post-concussive symptoms at one month (OR = 1.55;p = .048). Among those without LOC, AMS was associated with depressive symptoms at one month (OR = 2.24; p = .028). Conclusions: AMS predicts post-mTBI depressive symptoms both in the acute and chronic mTBI phases whereas LOC is a more sensitive predictor of post-concussive symptoms in the acute mTBI period.

Influence of study population definition on the effect of age on outcomes after blunt head trauma.

OBJECTIVES: The purpose of this study was to assess whether study population definition influences the effect of age on outcomes after blunt head trauma. We hypothesized that examining 'all comers' receiving head computerized tomography after blunt head trauma, fewer older individuals would meet Veterans Administration and Department of Defense (VA/DoD) criteria for traumatic brain injury (TBI), and would, therefore, display better outcomes than younger cohorts. However, restricting to participants meeting VA/DoD criteria for TBI, we hypothesized that older individuals would have worse outcomes. METHODS: Data from a recently completed prospective cohort study were analysed with age dichotomized at 65 years. Logistic regression modelling, controlled for potential confounders including head trauma severity, was estimated to measure the effect of age on functional recovery, post-concussion symptoms (PCS), and depressive symptoms at 1-month post-TBI. RESULTS: Fewer older than younger individuals met VA/DoD criteria for TBI. Older individuals had better functional, PCS, and depressive outcomes at 1 month. Restricting to those meeting VA/DoD criteria for TBI, older individuals continued to have better functional and PCS outcomes but had outcomes comparable to younger on depressive symptoms. CONCLUSIONS: Contrary to our hypothesis, there was a tendency for older adults to have better outcomes than younger, independent of the diagnostic criteria applied.

Poor sleep is linked to impeded recovery from traumatic brain injury.

Study Objectives: While disruptions in sleep are common after mild traumatic brain injury (TBI), the longitudinal relationships between sleep problems and global functioning after injury are poorly understood. Here, we prospectively investigate risk for functional impairment during the first 6 months of TBI recovery based on sleep onset insomnia symptoms and short sleep. Methods: Patients presenting to the Emergency Department (ED) at Johns Hopkins Hospital within 24 hours of head injury and evaluated for TBI were eligible for our study. Demographic and injury-related information were collected in the ED. Patients then completed in-person surveys and phone interviews to provide follow-up data on global functioning, sleep, and depressive symptoms at 1, 3, and 6 months post-injury. A total of 238 patients provided sufficient data for analysis, and hypotheses were tested using mixed effects modeling. Results: Sleep quality and global functioning improved over the 6 months of TBI recovery, but patients were at increased risk for functional impairment when sleeping poorly (odds ratio [OR] = 7.69, p < .001). Sleep onset insomnia symptoms and short sleep both independently corresponded to poor global functioning. Functional impairment was highest among those with both insomnia and short sleep (43%-79%) compared to good sleepers (15%-25%) and those with short sleep (29%-33%) or insomnia alone (33%-64%). A bidirectional relationship between sleep quality and functioning was observed. Conclusions: Functionally impaired patients diagnosed predominantly with mild TBI exhibit high rates of insomnia and short sleep, which may impede TBI recovery. Monitoring sleep after head injury may identify patients with poor prognoses and allow for early intervention to improve functional outcomes.

Derivation of a Three Biomarker Panel to Improve Diagnosis in Patients with Mild Traumatic Brain Injury.

BACKGROUND: Nearly 5 million emergency department (ED) visits for head injury occur each year in the United States, of which <10% of patients show abnormal computed tomography (CT) findings. CT negative patients frequently suffer protracted somatic, behavioral, and neurocognitive dysfunction. Our goal was to evaluate biomarkers to identify mild TBI (mTBI) in patients with suspected head injury. METHODS: An observational ED study of head-injured and control patients was conducted at Johns Hopkins University (HeadSMART). Head CT was obtained (ACEP criteria) in patients with Glasgow Coma Scale scores of 13-15 and aged 18-80. Three candidate biomarker proteins, neurogranin (NRGN), neuron-specific enolase (NSE), and metallothionein 3 (MT3), were evaluated by immunoassay (samples <24 h from injury). American Congress of Rehabilitation Medicine (ACRM) criteria were used for diagnosis of mTBI patients for model building. Univariate analysis, logistic regression, and random forest (RF) algorithms were used for data analysis in R. Overall, 662 patients were studied. Statistical models were built using 328 healthy controls and 179 mTBI patients. RESULTS: Median time from injury was 5.9 h (IQR, 4.0; range 0.8-24 h). mTBI patients had elevated NSE, but decreased MT3 versus controls (p < 0.01 for each). NRGN was also elevated but within 2-6 h after injury. In the derivation set, the best model to distinguish mTBI from healthy controls used three markers, age, and sex as covariates (C-statistic = 0.91, sensitivity 98%, specificity 72%). Panel test accuracy was validated with the 155 remaining ACRM+ mTBI patients. Applying the RF model to the ACRM+ mTBI validation set resulted in 78% correctly classified as mTBI (119/153). CT positive and CT negative validation subsets were 91% and 75% correctly classified. In samples taken <2 h from injury, 100% (10/10) samples classified correctly, indicating that hyperacute testing is possible with these biomarker assays. The model accuracy varied from 72-100% overall, and had greater accuracy with increasing severity, as shown by comparing CT+ with CT- (91% versus 75%), and Injury Severity Score ≥16 versus <16 (88% versus 72%, respectively). Objective blood tests, detecting NRGN, NSE, and MT3, can be used to identify mTBI, irrespective of neuroimaging findings.

Prevalence of Incomplete Functional and Symptomatic Recovery among Patients with Head Injury but Brain Injury Debatable.

Head injury patients not meeting the American Congress of Rehabilitation Medicine (ACRM)'s criteria for mild traumatic brain injury (mTBI), referred to hereafter as HIBRID (Head Injury BRain Injury Debatable), are often excluded from studies. The prognostic importance of HIBRID is unclear. We investigated the differences in functional and symptomatic recovery at 1 month post-injury among TBI patients classified as: HIBRID, ACRM+ cranial computed tomography (CT)-, and cranial CT+; and trauma and healthy controls. Subjects were enrolled in an ongoing prospective cohort (Head Injury Serum Markers for Assessing Response to Trauma; HeadSMART). Outcomes measured at 1 month post-injury include: incomplete functional recovery (Glasgow Outcome Scale Extended <8); moderate/severe post-concussive symptoms (PCS), defined according to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision definition; and moderate/severe depressive symptoms (Patient Health Questionnaire 9 ≥ 10). Between April 2014 and May 2016, 500 TBI and 100 control subjects were enrolled and 376 TBI and 78 control subjects completed outcome assessment. The HIBRID group, constituting 23.9% of study population, had a lower incidence of incomplete functional recovery (36.7% [33 of 90]) than ACRM+, CT- (60.7% [125 of 206]; p < 0.01) and CT+ (78.8% [63 of 80]; p < 0.01) groups. However, the incidence of delayed functional recovery within the HIBRID group was higher than in trauma (9.3% [5 of 54]; p < 0.01) and healthy controls (0% [0 of 24]; p < 0.01). Compared to trauma/healthy controls, the HIBRID group had a higher incidence of moderate/severe depressive symptoms and a similar incidence of moderate/severe PCS. Subjects in the HIBRID group are at high risk for adverse outcomes following head injury and warrant further investigation.

Molecular subgroups of atypical teratoid rhabdoid tumours in children: an integrated genomic and clinicopathological analysis.

BACKGROUND: Rhabdoid brain tumours, also called atypical teratoid rhabdoid tumours, are lethal childhood cancers with characteristic genetic alterations of SMARCB1/hSNF5. Lack of biological understanding of the substantial clinical heterogeneity of these tumours restricts therapeutic advances. We integrated genomic and clinicopathological analyses of a cohort of patients with atypical teratoid rhabdoid tumours to find out the molecular basis for clinical heterogeneity in these tumours. METHODS: We obtained 259 rhabdoid tumours from 37 international institutions and assessed transcriptional profiles in 43 primary tumours and copy number profiles in 38 primary tumours to discover molecular subgroups of atypical teratoid rhabdoid tumours. We used gene and pathway enrichment analyses to discover group-specific molecular markers and did immunohistochemical analyses on 125 primary tumours to evaluate clinicopathological significance of molecular subgroup and ASCL1-NOTCH signalling. FINDINGS: Transcriptional analyses identified two atypical teratoid rhabdoid tumour subgroups with differential enrichment of genetic pathways, and distinct clinicopathological and survival features. Expression of ASCL1, a regulator of NOTCH signalling, correlated with supratentorial location (p=0·004) and superior 5-year overall survival (35%, 95% CI 13-57, and 20%, 6-34, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·033) in 70 patients who received multimodal treatment. ASCL1 expression also correlated with superior 5-year overall survival (34%, 7-61, and 9%, 0-21, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·001) in 39 patients who received only chemotherapy without radiation. Cox hazard ratios for overall survival in patients with differential ASCL1 enrichment treated with chemotherapy with or without radiation were 2·02 (95% CI 1·04-3·85; p=0·038) and 3·98 (1·71-9·26; p=0·001). Integrated analyses of molecular subgroupings with clinical prognostic factors showed three distinct clinical risk groups of tumours with different therapeutic outcomes. INTERPRETATION: An integration of clinical risk factors and tumour molecular groups can be used to identify patients who are likely to have improved long-term radiation-free survival and might help therapeutic stratification of patients with atypical teratoid rhabdoid tumours. FUNDING: C17 Research Network, Genome Canada, b.r.a.i.n.child, Mitchell Duckman, Tal Doron and Suri Boon foundations.

TERT promoter mutations are highly recurrent in SHH subgroup medulloblastoma.

Telomerase reverse transcriptase (TERT) promoter mutations were recently shown to drive telomerase activity in various cancer types, including medulloblastoma. However, the clinical and biological implications of TERT mutations in medulloblastoma have not been described. Hence, we sought to describe these mutations and their impact in a subgroup-specific manner. We analyzed the TERT promoter by direct sequencing and genotyping in 466 medulloblastomas. The mutational distributions were determined according to subgroup affiliation, demographics, and clinical, prognostic, and molecular features. Integrated genomics approaches were used to identify specific somatic copy number alterations in TERT promoter-mutated and wild-type tumors. Overall, TERT promoter mutations were identified in 21 % of medulloblastomas. Strikingly, the highest frequencies of TERT mutations were observed in SHH (83 %; 55/66) and WNT (31 %; 4/13) medulloblastomas derived from adult patients. Group 3 and Group 4 harbored this alteration in <5 % of cases and showed no association with increased patient age. The prognostic implications of these mutations were highly subgroup-specific. TERT mutations identified a subset with good and poor prognosis in SHH and Group 4 tumors, respectively. Monosomy 6 was mostly restricted to WNT tumors without TERT mutations. Hallmark SHH focal copy number aberrations and chromosome 10q deletion were mutually exclusive with TERT mutations within SHH tumors. TERT promoter mutations are the most common recurrent somatic point mutation in medulloblastoma, and are very highly enriched in adult SHH and WNT tumors. TERT mutations define a subset of SHH medulloblastoma with distinct demographics, cytogenetics, and outcomes.

Novel report of expression and function of CD97 in malignant gliomas: correlation with Wilms tumor 1 expression and glioma cell invasiveness.

OBJECT: The Wilms tumor 1 (WT1) protein-a developmentally regulated transcription factor-is aberrantly expressed in gliomas and promotes their malignant phenotype. However, little is known about the molecular allies that help it mediate its oncogenic functions in glioma cells. METHODS: The authors used short interfering RNA (siRNA) to suppress WT1 expression in glioblastoma (GBM) cells and evaluated the effect of this on GBM cell invasiveness. Gene expression analysis was then used to identify the candidate genes that were altered as a result of WT1 silencing. One candidate target, CD97, was then selected for further investigation into its role by suppressing its expression using siRNA silencing, followed by proliferation and invasion assays. RESULTS: WT1 levels were reliably and reproducibly suppressed by siRNA application. This resulted in a significant decrease in cellular invasiveness. Microarray analyses identified the gene products that were consistently downregulated (27) and upregulated (11) with WT1 silencing. Of these, CD97 expression was consistently suppressed across the 3 different GBM cell lines studied and was found on further investigation to significantly impact GBM cell invasiveness. CONCLUSIONS: Although CD97 expression in gliomas has not been described previously, we conclude that the possible upregulation of CD97 mediated by WT1 promotes cellular invasiveness-one of the most characteristic and challenging aspects of glial tumor cells. Further studies are needed to clarify the nature of this regulation and its impact, as CD97 could represent a novel target for antiglioma therapies.

Sunitinib induces apoptosis and growth arrest of medulloblastoma tumor cells by inhibiting STAT3 and AKT signaling pathways.

Medulloblastomas are the most frequent malignant brain tumors in children. Sunitinib is an oral multitargeted tyrosine kinase inhibitor used in clinical trials as an antiangiogenic agent for cancer therapy. In this report, we show that sunitinib induced apoptosis and inhibited cell proliferation of both a short-term primary culture (VC312) and an established cell line (Daoy) of human medulloblastomas. Sunitinib treatment resulted in the activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase and upregulation of proapoptotic genes, Bak and Bim, and inhibited the expression of survivin, an antiapoptotic protein. Sunitinib treatment also downregulated cyclin E, cyclin D2, and cyclin D3 and upregulated p21Cip1, all of which are involved in regulating cell cycle. In addition, it inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and AKT (protein kinase B) in the tumor cells. Dephosphorylation of STAT3 (Tyr(705)) induced by sunitinib was helped by a reduction in activities of Janus-activated kinase 2 and Src. Additionally, sodium vanadate, an inhibitor of protein tyrosine phosphatases, partially blocked the inhibition of phosphorylated STAT3 by sunitinib. Loss of phosphorylated AKT after sunitinib treatment was accompanied by decreased phosphorylation of downstream proteins glycogen synthase kinase-3beta and mammalian target of rapamycin. Expression of a constitutively activated STAT3 mutant or myristoylated AKT partially blocked the effects of sunitinib in these tumor cells. Sunitinib also inhibited the migration of medulloblastoma tumor cells in vitro. These findings suggest the potential use of sunitinib for the treatment of pediatric medulloblastomas.

Effect of WT1 gene silencing on the tumorigenicity of human glioblastoma multiforme cells.

OBJECT: Wilms tumor 1 (WT1) is overexpressed in many human cancers, including glioblastoma multiforme (GBM). In another study, the authors showed that transient WT1 silencing increases the radiosensitivity of glioma cells. Studies of nonglioma cell lines have demonstrated that WT1 promotes cell proliferation and survival; however, this ability has not been rigorously analyzed in human GBM. METHODS: The authors tested the efficacy of 2 sequences of short hairpin RNA (shRNA) directed against WT1 in U251MG human GBM cells and found that 1 sequence was capable of stably silencing WT1 expression. They then evaluated the effect of WT1 silencing on cellular proliferation, invasion, and in vivo tumor formation. RESULTS: Stable WT1-shRNA expression significantly decreased the proliferation of U251MG cells in vitro as demonstrated by both an adenosine 5'-triphosphate-based viability assay and tritiated thymidine uptake. Furthermore, stable WT1 silencing caused significantly slower growth after the subcutaneous inoculation of tumor cells in the flanks of athymic nude mice and was associated with an increased latency period. CONCLUSIONS: Data in this study provide proof of the principle that downregulation of WT1 causes decreased tumorigenicity of a GBM cell line in vitro and in vivo and suggest that WT1 is a promising target for novel molecular GBM therapies, perhaps in combination with standard treatment modalities.

The alkylphospholipid perifosine induces apoptosis and p21-mediated cell cycle arrest in medulloblastoma.

Medulloblastoma is the most common malignant cancer of the central nervous system in children. AKT kinases are part of a survival pathway that has been found to be significantly elevated in medulloblastoma. This pathway is a point of convergence for many growth factors and controls cellular processes that are critical for tumor cell survival and proliferation. The alkyl-phospholipid perifosine [octadecyl-(1,1-dimethyl-4-piperidylio) phosphate] is a small molecule inhibitor in clinical trials in peripheral cancers which acts as a competitive inhibitor of AKT kinases. Medulloblastoma cell cultures were used to study the effects of perifosine response in preclinical studies in vitro. Perifosine treatment led to the rapid induction of cell death in medulloblastoma cell lines, with pronounced suppression of phosphorylated AKT in a time-dependent and concentration-dependent manner. LD(50) concentrations were established using viability assays for perifosine, cisplatin, and etoposide. LD(50) treatment of medulloblastoma cells with perifosine led to the cleavage of caspase 9, caspase 7, caspase 3, and poly-ADP ribosylation protein, although caspase 8 was not detectable. Combination single-dose treatment regimens of perifosine with sublethal doses of etoposide or irradiation showed a greater than additive effect in medulloblastoma cells. Lower perifosine concentrations induced cell cycle arrest at the G(1) and G(2) cell cycle checkpoints, accompanied by increased expression of the cell cycle inhibitor p21(cip1/waf1). Treatment with p21 small interfering RNA prevented perifosine-induced cell cycle arrest. These findings indicate that perifosine, either alone or in combination with other chemotherapeutic drugs, might be an effective therapeutic agent for the treatment of medulloblastoma.

Sorafenib inhibits signal transducer and activator of transcription 3 signaling associated with growth arrest and apoptosis of medulloblastomas.

Medulloblastomas are the most frequent malignant brain tumors in children. Sorafenib (Nexavar, BAY43-9006), a multikinase inhibitor, blocks cell proliferation and induces apoptosis in a variety of tumor cells. Sorafenib inhibited proliferation and induced apoptosis in two established cell lines (Daoy and D283) and a primary culture (VC312) of human medulloblastomas. In addition, sorafenib inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) in both cell lines and primary tumor cells. The inhibition of phosphorylated STAT3 (Tyr(705)) occurs in a dose- and time-dependent manner. In contrast, AKT (protein kinase B) was only decreased in D283 and VC312 medulloblastoma cells and mitogen-activated protein kinases (extracellular signal-regulated kinase 1/2) were not inhibited by sorafenib in these cells. Both D-type cyclins (D1, D2, and D3) and E-type cyclin were down-regulated by sorafenib. Also, expression of the antiapoptotic protein Mcl-1, a member of the Bcl-2 family, was decreased and correlated with apoptosis induced by sorafenib. Finally, sorafenib suppressed the growth of human medulloblastoma cells in a mouse xenograft model. Together, our data show that sorafenib blocks STAT3 signaling as well as expression of cell cycle and apoptosis regulatory proteins, associated with inhibition of cell proliferation and induction of apoptosis in medulloblastomas. These findings provide a rationale for treatment of pediatric medulloblastomas with sorafenib.

Wilms tumor 1 expression in malignant gliomas and correlation of +KTS isoforms with p53 status.

OBJECT: The WT1 gene is overexpressed in many types of human cancer. It has been demonstrated that Wilms tumor 1 (WT1) promotes tumor cell proliferation and survival in some cell lines by inhibiting p53-mediated apoptosis; however, this relationship has not been investigated in gliomas. The goal in this study was to characterize the expression pattern of WT1 in human gliomas and to determine if a correlation exists between WT1 expression and p53 status. METHODS: The authors screened nine malignant glioma cell lines, 50 glioblastoma multiforme (GBM) samples, and 16 lower-grade glial tumors for WT1 expression. RESULTS: Five of nine cell lines, 44 of 50 GBM samples, and 13 of 16 lower-grade gliomas expressed WT1 mRNA on reverse transcriptase polymerase chain reaction (PCR) analysis. Expression of WT1 was not detected in normal astrocytes. Two WT1 isoforms, +/+ and -/+, were expressed in the majority of these samples. Real-time PCR analysis of the GBM cell lines revealed that the level of WT1 mRNA ranged from 6.33 to 214.70 ng per ng 18S ribosomal RNA. The authors screened the GBM samples for p53 mutation by using PCR and single-stranded conformational polymorphism analysis, and they demonstrated an association between WT1 expression and p53 status. Tumors that contained wild-type p53 were significantly more likely to express WT1 than tumors that contained mutant p53. CONCLUSIONS: The presence of WT1 in glioma cell lines and the majority of primary tumor samples and its absence in normal astrocytes support the suggestion that WT1 expression is important in glioma biology.

Down-regulation of Wilms' tumor 1 expression in glioblastoma cells increases radiosensitivity independently of p53.

The Wilms' tumor 1 (WT1) gene is overexpressed in human glioblastoma and correlates with wild-type p53 status. In other cell types, WT1 inhibits p53-mediated apoptosis in response to DNA damaging agents. However, neither this interaction nor the relationship between WT1 and radiosensitivity has been studied in glioblastoma. To study this interaction, we generated LN-229 glioma cell lines (p53 mutant) stably expressing WT1 isoforms and induced apoptosis by transfecting with different doses of wild-type p53 plasmid expression vector. Constitutive expression of WT1 did not protect against exogenous p53-mediated apoptosis. Likewise, WT1 expression did not protect against endogenous p53-mediated cell death induced by radiotherapy in U87MG cells, which contain functional wild-type p53. We then tested the efficacy of WT1 siRNA in inhibiting WT1 expression and its effect on radiosensitivity. In T98G and LN-18 glioma cells, which possess p53 mutations, WT1 siRNA decreased WT1 protein to almost undetectable levels by 96-h post-transfection. Furthermore, WT1 siRNA transfection caused a significantly larger decrease in viability following irradiation than was seen in untransfected cells in both cell lines after treatment with ED50 of ionizing radiation. In conclusion, WT1 overexpression did not protect against p53-mediated apoptosis or ionizing radiation induced cell death. WT1 siRNA increased the radiosensitivity of two human glioma cell lines independently of p53. Anti-WT1 strategies may, therefore, prove useful in improving the response of glioblastoma to radiotherapy, thus potentially improving patient survival.