Noncoding RNAs in Glioblastoma: Emerging Biological Concepts and Potential Therapeutic Implications.

Noncoding RNAs (ncRNAs) have emerged as a novel class of genomic regulators, ushering in a new era in molecular biology. With the advent of advanced genetic sequencing technology, several different classes of ncRNAs have been uncovered, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and piwi-interacting RNAs (piRNAs), which have been linked to many important developmental and disease processes and are being pursued as clinical and therapeutic targets. Molecular phenotyping studies of glioblastoma (GBM), the most common and lethal cancer of the adult brain, revealed that several ncRNAs are frequently dysregulated in its pathogenesis. Additionally, ncRNAs regulate many important aspects of glioma biology including tumour cell proliferation, migration, invasion, apoptosis, angiogenesis, and self-renewal. Here, we present an overview of the biogenesis of the different classes of ncRNAs, discuss their biological roles, as well as their relevance to gliomagenesis. We conclude by discussing potential approaches to therapeutically target the ncRNAs in clinic.

Modeling human brain tumors in flies, worms, and zebrafish: From proof of principle to novel therapeutic targets.

For decades, cell biologists and cancer researchers have taken advantage of non-murine species to increase our understanding of the molecular processes that drive normal cell and tissue development, and when perturbed, cause cancer. The advent of whole-genome sequencing has revealed the high genetic homology of these organisms to humans. Seminal studies in non-murine organisms such as Drosophila melanogaster, Caenorhabditis elegans, and Danio rerio identified many of the signaling pathways involved in cancer. Studies in these organisms offer distinct advantages over mammalian cell or murine systems. Compared to murine models, these three species have shorter lifespans, are less resource intense, and are amenable to high-throughput drug and RNA interference screening to test a myriad of promising drugs against novel targets. In this review, we introduce species-specific breeding strategies, highlight the advantages of modeling brain tumors in each non-mammalian species, and underscore the successes attributed to scientific investigation using these models. We conclude with an optimistic proposal that discoveries in the fields of cancer research, and in particular neuro-oncology, may be expedited using these powerful screening tools and strategies.

BMP signaling mediates glioma stem cell quiescence and confers treatment resistance in glioblastoma.

Despite advances in therapy, glioblastoma remains an incurable disease with a dismal prognosis. Recent studies have implicated cancer stem cells within glioblastoma (glioma stem cells, GSCs) as mediators of therapeutic resistance and tumor progression. In this study, we investigated the role of the transforming growth factor-ß (TGF-ß) superfamily, which has been found to play an integral role in the maintenance of stem cell homeostasis within multiple stem cell systems, as a mediator of stem-like cells in glioblastoma. We find that BMP and TGF-ß signaling define divergent molecular and functional identities in glioblastoma, and mark relatively quiescent and proliferative GSCs, respectively. Treatment of GSCs with BMP inhibits cell proliferation, but does not abrogate their stem-ness, as measured by self-renewal and tumorigencity. Further, BMP pathway activation confers relative resistance to radiation and temozolomide chemotherapy. Our findings define a quiescent cancer stem cell population in glioblastoma that may be a cellular reservoir for tumor recurrence following cytotoxic therapy.

A role for activated Cdc42 in glioblastoma multiforme invasion.

Cdc42 is a Rho-GTPase which plays a major role in regulating cell polarity and migration by specifying the localization of filopodia. However, the role of Cdc42 in GBM invasion has not been thoroughly investigated. We generated stable doxycycline-inducible clones expressing wild type (WT)-, constitutively active (CA)-, and dominant negative (DN)-Cdc42 in three different human glioma cell lines. Expression of CA-Cdc42 significantly increased the migration and invasive properties of malignant glioma cells compared to WT and DN-Cdc42 cell clones, and this was accompanied by a greater number of filopodia and focal adhesion structures which co-localize with phosphorylated focal adhesion kinase (FAK). By mass spectrometry and immunoprecipitation studies, we demonstrated that activated Cdc42 binds to IQGAP1. When implanted orthotopically in mice, the CA-Cdc42 expressing glioma cells exhibited enhanced local migration and invasion, and led to larger tumors, which significantly reduced survival. Using the Cancer Genome Atlas dataset, we determined that high Cdc42 expression is associated with poorer progression free survival, and that Cdc42 expression is highest in the proneural and neural subgroups of GBM. In summary, our studies demonstrate that activated Cdc42 is a critical determinant of the migratory and invasive phenotype of malignant gliomas, and that its effect may be mediated, at least in part, through its interaction with IQGAP1 and phosphorylated FAK.

Randomized controlled trial of gabapentin as an adjunct to perioperative analgesia in total hip arthroplasty patients.

PURPOSE: Gabapentin was investigated as a single-dose adjunct to morphine for postoperative pain management. The primary objective was to determine if gabapentin given preoperatively and for two days postoperatively as part of multimodal analgesia would decrease postoperative morphine consumption in patients undergoing primary total hip arthroplasty (THA). METHODS: The study group included 102 patients aged 19-90 years who were undergoing primary THA in a single joint with no contraindications to the study medications, no chronic pain syndrome, and no chronic opioid use. Intervention group patients (n = 48) received gabapentin 600 mg po preoperatively and 200 mg postoperatively on the day of surgery. They were continued on gabapentin at 200 mg three times daily for two days. Control group patients (n = 54) received placebo in a similar fashion. Preoperatively, all patients were given 30 mg of ketorolac intravenously and acetaminophen 1000 mg po. Postoperatively, they received intravenous patient-controlled analgesia with morphine, along with ketorolac 15 mg iv and acetaminophen 1000 mg po every six hours. RESULTS: The primary outcome was mean (SD) postoperative morphine consumption at 72 hr which was 55.8 (39.2) mg in the gabapentin groups vs 60.7 (37.2) mg for the control group (mean difference, -4.91 mg, 95% confidence intervals [CI]: -21.2 to 11.35; P = 0.550). There were no significant differences between the groups regarding secondary outcomes: pain scores, side effects, range of motion. Patient satisfaction on day 3 was more favourable in the placebo group. Length of hospitalization was marginally shorter in the placebo group. CONCLUSIONS: This trial indicated that gabapentin treatment had no clinically important reduction in postoperative morphine consumption at 72 hr in patients undergoing THA. Multimodal analgesia may account for the similar primary and secondary outcomes found in the groups. This trial was registered at ClinicalTrials.gov, number: NCT01307202.

Reanalysis of morphine consumption from two randomized controlled trials of gabapentin using longitudinal statistical methods.

BACKGROUND: Postoperative pain management in total joint replacement surgery remains ineffective in up to 50% of patients and has an overwhelming impact in terms of patient well-being and health care burden. We present here an empirical analysis of two randomized controlled trials assessing whether addition of gabapentin to a multimodal perioperative analgesia regimen can reduce morphine consumption or improve analgesia for patients following total joint arthroplasty (the MOBILE trials). METHODS: Morphine consumption, measured for four time periods in patients undergoing total hip or total knee arthroplasty, was analyzed using a linear mixed-effects model to provide a longitudinal estimate of the treatment effect. Repeated-measures analysis of variance and generalized estimating equations were used in a sensitivity analysis to compare the robustness of the methods. RESULTS: There was no statistically significant difference in morphine consumption between the treatment group and a control group (mean effect size estimate 1.0, 95% confidence interval -4.7, 6.7, P=0.73). The results remained robust across different longitudinal methods. CONCLUSION: The results of the current reanalysis of morphine consumption align with those of the MOBILE trials. Gabapentin did not significantly reduce morphine consumption in patients undergoing major replacement surgeries. The results remain consistent across longitudinal methods. More work in the area of postoperative pain is required to provide adequate management for this patient population.

Transmyocardial Revascularization Enhances Bone Marrow Stem Cell Engraftment in Infarcted Hearts Through SCF-C-kit and SDF-1-CXCR4 Signaling Axes.

BACKGROUND: We investigated the roles of stem cell factor (SCF)-c-kit and stromal derived factor-1 (SDF-1)-CXCR4 signaling axes in transmyocardial revascularization (TMR)-enhanced engraftment of transplanted bone marrow stem cells (BMSCs) in infarcted hearts. METHODS: 3 weeks after LAD ligation, female Lewis rats underwent 10-channel needle-TMR, followed by daily IV injections of 1 million male donor BMSC for 5 days, either wild type (WT) or with knockdown (K/D) of c-kit or CXCR4, accomplished via a shRNA + plasmid in a lentiviral vector (N = 6/group). RESULTS: In our rat infarct model, 3 days after last BMSC injection, the number of BMSCs that homed into infarct was affected by both TMR and donor cell type, with greater BMSC engraftment with TMR and with WT BMSC (TMR, cell type, and interaction, P < 0.05). At 1 week, these differences persisted (TMR and cell type, P < 0.05). At 3 days, TMR significantly upregulated transcription of c-kit (TMR, p < 0.05), SCF (TMR and cell type, P < 0.05), CXCR4 (TMR and cell type, p < 0.05), and SDF-1 (TMR and cell type, P < 0.05). At 1 week, we saw similar declines in expression of c-kit (cell type, P < 0.05), SCF (TMR, P < 0.05), CXCR4 (TMR and cell type, P < 0.05), and SDF-1 (TMR, P < 0.05). At 1 week, TMR improved LV ejection fraction (LVEF) (N = 5) when WT BMSCs were infused, but knockdown of either c-kit or CXCR4 completely abrogated this TMR-mediated augmentation of BMSC reparative effect (TMR and cell type, P < 0.05). CONCLUSIONS: Downregulation of either c-kit or CXCR4 in BMSC decreased engraftment of circulating BMSC and inhibited reparative effects of TMR.

The current state of stem cell therapeutics: Canadian approaches in the international context.

After ischemic injury, the endogenous repair mechanisms of the human heart are insufficient for meaningful tissue regeneration, so muscle lost is replaced by noncontractile scar tissue. Current treatments for ischemic cardiomyopathy improve quality of life and increase life expectancy, but cannot cure the underlying disease of cardiomyocyte loss. Cellular transplantation is emerging as a valuable therapeutic approach to heal the ischemic heart. Adult bone marrow stem cells are capable of differentiation, regeneration of infarcted myocardium, and induction of myogenesis and angiogenesis, ultimately leading to improved contractility. Positive results from animal studies have prompted several clinical trials to ascertain the safety and feasibility of cell therapy. However, despite all the excitement in stem cell research resulting from initial experimental data and preliminary clinical trials, the mixed results observed have raised many unanswered questions. A major obstacle to the identification of the optimal cell therapy is that the fate of the implanted cells and the nature of their beneficial effects are ill-defined. A better understanding is fundamental for the development of new therapeutic agents, and to optimize stem cell applications. Well-designed and powered double-blinded randomized studies are clearly needed to confirm promising findings from early studies. With several ongoing randomized trials directed toward evaluation of stem cell therapies in patients with acute or chronic ischemic cardiomyopathy, the Canadian initiative represents a milestone.

Empirical comparison of four baseline covariate adjustment methods in analysis of continuous outcomes in randomized controlled trials.

BACKGROUND: Although seemingly straightforward, the statistical comparison of a continuous variable in a randomized controlled trial that has both a pre- and posttreatment score presents an interesting challenge for trialists. We present here empirical application of four statistical methods (posttreatment scores with analysis of variance, analysis of covariance, change in scores, and percent change in scores), using data from a randomized controlled trial of postoperative pain in patients following total joint arthroplasty (the Morphine COnsumption in Joint Replacement Patients, With and Without GaBapentin Treatment, a RandomIzed ControlLEd Study [MOBILE] trials). METHODS: Analysis of covariance (ANCOVA) was used to adjust for baseline measures and to provide an unbiased estimate of the mean group difference of the 1-year postoperative knee flexion scores in knee arthroplasty patients. Robustness tests were done by comparing ANCOVA with three comparative methods: the posttreatment scores, change in scores, and percentage change from baseline. RESULTS: All four methods showed similar direction of effect; however, ANCOVA (-3.9; 95% confidence interval [CI]: -9.5, 1.6; P=0.15) and the posttreatment score (-4.3; 95% CI: -9.8, 1.2; P=0.12) method provided the highest precision of estimate compared with the change score (-3.0; 95% CI: -9.9, 3.8; P=0.38) and percent change (-0.019; 95% CI: -0.087, 0.050; P=0.58). CONCLUSION: ANCOVA, through both simulation and empirical studies, provides the best statistical estimation for analyzing continuous outcomes requiring covariate adjustment. Our empirical findings support the use of ANCOVA as an optimal method in both design and analysis of trials with a continuous primary outcome.

Transmyocardial revascularization induces mesenchymal stem cell engraftment in infarcted hearts.

BACKGROUND: Transmyocardial revascularization (TMR) prior to mesenchymal stem cell (MSC) transplantation augments repair of infarcted hearts. We evaluated the effects of TMR on homing and engraftment of circulating MSCs and mediators of this effect. METHODS: Three weeks after left anterior descending coronary artery ligation in female rats, 10-channel needle TMR was performed in the infarct, followed by daily intravenous injections of 1 million male MSCs for 5 days. Control rats had MSC infusions without TMR (n=16/group). Donor MSC survival was evaluated at 3 days and at 1 week by quantitative polymerase chain reaction, as well as expression of stem cell factor (SCF), stromal derived factor-1 (SDF-1), c-kit, and chemokine receptor type 4 (CXCR4). RESULTS: The MSCs engrafted into the infarct, clustering around TMR channels. The MSC engraftment was greater in TMR hearts at 3 days and at 1 week. Both SCF (p=0.03) and c-kit (p=0.01) were upregulated by TMR at 3 days, but their levels fell at 1 week (p=0.3, p=0.5, respectively). The SDF-1 levels were higher in TMR hearts at both 3 days (p=0.04) and at 1 week (p=0.04). The CXCR4 was upregulated early by TMR (p=0.0002) but levels dropped dramatically at 1 week (p=0.045). CONCLUSIONS: Transmyocardial revascularization induces transmigration and engraftment of circulating MSCs. Post TMR, the transcription of SCF and c-kit is rapid and corresponds temporally to MSC engraftment, while SDF-1 levels rise slowly. The CXCR4 is also transiently upregulated. The TMR-augmented repair of infarcted hearts by stem cell transplantation may be mediated by a novel mechanism: transmigration and engraftment of circulating progenitor cells.

Reliability of 3 assessment tools used to evaluate randomized controlled trials for treatment of neck pain.

STUDY DESIGN: Pragmatic, cross-sectional study. OBJECTIVE: To assess the interrater reliability of 3 tools used by the Cervical Overview Group (COG) for the assessment of the internal validity of randomized controlled trials (RCTs): Jadad, van Tulder, and risk of bias (RoB). SUMMARY OF BACKGROUND DATA: For clinicians to implement evidence-based practice, they need to critically appraise health care literature. Checklists, scales, and domain-based criteria exist to evaluate the internal validity of RCTs for rehabilitation studies, but there is a lack of research reporting the reliability of existing assessment tools. METHODS: Four members of the COG with multiprofessional and methodological background independently evaluated the internal validity of 54 RCTs using prepiloted Jadad and van Tulder reporting forms, and 18 RCTs using RoB, from June 2003 to May 2009. The κ statistic was calculated for each combination of raters and assessment tools. Standard agreement categorizations were used. RESULTS: For Jadad, 4 of 7 items demonstrated mean κ statistic ranges from moderate to substantial agreement (mean values, 0.42-0.78), as did 8 of 11 items on the van Tulder tool (mean values, 0.44-0.77). The RoB demonstrated moderate to substantial (mean values, 0.56-0.76) agreement on 3 of 12 items. Consistent substantial agreement was found across all assessment tools for the domain "allocation concealment": Jadad 0.69 (mean range, 0.60-0.77); van Tulder 0.77 (mean range, 0.73-0.81); RoB 0.76 (mean range, 0.65-0.88); and moderate to substantial across 2 tools for the domain "sequence generation": van Tulder 0.53 (mean range, 0.37-0.66) and RoB 0.66 (mean range, 0.45-0.88). Other domains demonstrated slight or fair agreement. CONCLUSION: Consistent interrater agreement was found across the 3 assessment tools for allocation concealment and for 2 tools for sequence generation. However, users should acknowledge that moderate variation exists within other items requiring more judgment. When evaluating rehabilitation RCTs, clinicians should consider limitations of rating certain items within the selected assessment tool.