The effect of light emitting diode phototherapy on rate of orthodontic tooth movement: a split mouth, controlled clinical trial.

OBJECTIVE: Increasing the rate of orthodontic tooth movement (OTM) can reduce risks such as periodontal disease and caries. TRIAL DESIGN: This split-mouth randomized controlled clinical trial investigated whether light emitting diode (LED) phototherapy could accelerate the rate of OTM. SETTING: The study was conducted at the Graduate Orthodontics Clinic at the University of Toronto, Faculty of Dentistry. PARTICIPANTS AND METHODS: 17 dental arches from 11 orthodontic participants with bilaterally symmetrical extraction of premolars were included. During space closure of single tooth extraction sites, LED phototherapy was applied to one side of the dental arch for a specified time and the contralateral side acted as the control. Space closure was measured immediately prior to, during and later in space closure. RESULTS: All participants were compliant with LED application. Our results revealed no significant changes in the rate of OTM with LED phototherapy over 3 months of extraction space closure. CONCLUSIONS: Our findings were contrary to previous findings of the effect of laser phototherapy on regulating the rate of OTM. Further investigations are warranted to analyse whether the duration or method of LED delivery would have an effect on the rate of OTM. Toronto. This trial was registered at clinicaltrials.gov (NCT01490385).

Loss of CIC and FUBP1 expressions are potential markers of shorter time to recurrence in oligodendroglial tumors.

Combined deletion of chromosomes 1p and 19q is a prognostic marker in oligodendroglial tumors. Recent studies in oligodendroglial tumors have unveiled recurrent mutations of CIC (homolog of Drosophila capicua) and FUBP1 (far upstream element binding protein 1) that are located on 19q13 and 1p31, respectively. However, the impact of CIC and FUBP1 mutations on their protein expressions has not been examined. The aims of this study were to correlate the expression patterns of CIC and FUBP1 with their mutation profiles and to evaluate the clinical relevance of these molecular markers in 55 oligodendroglial tumors diagnosed in 47 adult patients. Using direct sequencing, somatic mutations of CIC and FUBP1 were identified in 47% (22/47) and 16% (7/45) of oligodendroglial tumors, respectively. Immunohistochemical analysis revealed loss of CIC or FUBP1 protein expression in 36% (20/55) and 16% (9/55) of oligodendroglial tumors examined. Somatic mutation was significantly associated with absent protein expression for both genes (CIC, P=0.01; FUBP1, P=0.00001). Four tumors with undetectable CIC mutations exhibited absent CIC expression, suggesting that CIC inactivation could be mediated by mechanisms other than mutations and genomic loss. Univariate survival analysis revealed that 1p/19q codeletion was significantly associated with overall survival (P=0.05). Loss of CIC expression was significantly correlated with shorter progression-free survival (P=0.03), whereas CIC alteration (mutation or null expression) with worse overall survival (P=0.05). Absent FUBP1 expression was linked with unfavorable progression-free survival (P=0.02) and overall survival (P=0.01). In 16 tumors with 1p/19q codeletion, CIC mutation was associated with unfavorable survival (P=0.01). There was a correlation between lack of CIC or FUBP1 expression and poor progression-free survival (P=0.004; P=0.0003). No molecular markers showed association with survival in oligodendroglial tumors lacking 1p/19q codeletion. We conclude that absent CIC and FUBP1 expressions are potential markers of shorter time to recurrence and CIC mutation a potential marker of worse prognosis, especially in tumors carrying 1p/19q codeletion.

Development of a novel and more holistic approach for assessing impact in health and medical research: the Research Impact Assessment Framework.

Considered investment in health and medical research (HMR) is critical for fostering a healthcare system that is sustainable, effective, responsive, and innovative. While several tools exist to measure the impact of research, few assess the research environment that nurtures and supports impactful research and the strategic alignment of research with societal needs. This perspective article discusses the limitations of existing assessment tools and presents a novel Research Impact Assessment Framework designed to enable more strategic and targeted investment towards HMR, having the potential for significant public benefit.

Ribosome Stalling of N-Linked Glycoproteins in Cell-Free Extracts.

Ribosome display is a powerful in vitro method for selection and directed evolution of proteins expressed from combinatorial libraries. However, the ability to display proteins with complex post-translational modifications such as glycosylation is limited. To address this gap, we developed a set of complementary methods for producing stalled ribosome complexes that displayed asparagine-linked (N-linked) glycoproteins in conformations amenable to downstream functional and glycostructural interrogation. The ability to generate glycosylated ribosome-nascent chain (glycoRNC) complexes was enabled by integrating SecM-mediated translation arrest with methods for cell-free N-glycoprotein synthesis. This integration enabled a first-in-kind method for ribosome stalling of target proteins modified efficiently and site-specifically with different N-glycan structures. Moreover, the observation that encoding mRNAs remained stably attached to ribosomes provides evidence of a genotype-glycophenotype link between an arrested glycoprotein and its RNA message. We anticipate that our method will enable selection and evolution of N-glycoproteins with advantageous biological and biophysical properties.

Clinical significance of vasculogenic mimicry in human gliomas.

Vasculogenic mimicry (VM) is known as non-endothelial tumor cell-lined microvascular channels in aggressive tumors. We have previously found the presence of VM in high-grade gliomas. In this study, we aimed to identify VM patterns in gliomas and to explore their clinical significance. Tumor samples as well as their detailed clinical/prognostic data were collected from 101 patients. Vasculogenic mimicry in the glioma samples was determined by dual staining for endothelial marker CD34 and periodic acid-Schiff (PAS). Tumor samples were also immunohistochemically stained for Ki-67, VEGF, COX-2 and MMP-9. The association between VM and the clinical characteristics of the patients were analyzed. A Kaplan-Meier survival analysis and log-rank tests were performed to compare survival times of the patients. Vasculogenic mimicry was present in 13 out of 101 samples. The higher grade gliomas had a higher incidence of VM than that of lower grade gliomas (P = 0.006). Vasculogenic mimicry channels were associated with the expression of COX-2 and MMP-9 (P < 0.05). While there was no association between the existence of VM and the sex, age and preoperative epilepsy of the patients, or expression of Ki-67 and VEGF. However, patients with VM-positive gliomas survived a shorter period of time than those with VM negative gliomas (P = 0.027). Interestingly, in high-grade gliomas, the level of microvascular density was lower in VM positive tumors than those VM negative tumors (P = 0.039). Our results suggest that VM channels in gliomas correlate with increasing malignancy and higher aggressiveness, and may provide a complementation to the tumor's blood supply, especially in less vascularized regions, which may aid in the identification of glioma patients with a poorer prognosis.

Immediate loading in the maxillary arch: evidence-based guidelines to improve success rates: a review.

The reliability of immediately loaded dental implants in the mandible has prompted many to investigate their application in the maxilla. Although the body of literature is growing, the long-term survivability of immediate loading in the maxilla is still pending. This review of literature investigates the status of immediate loading of dental implants in the maxilla to determine its predictability as a treatment option for partial and complete maxillary edentulism. Current terminology in the field is summarized first. Subsequently, the rationale and advantages of immediate loading in the maxilla are reviewed, and the relationships between immediate loading and osseointegration, primary stability, implant design, micromotion, immediate implant placement, and bone character are explored. The importance of a prosthodontically driven implant treatment plan emphasizing the role of splinting a high-precision and passively fitting implant restoration with reduced micromotion under function is summarized. The reliability and predictability of immediately loaded implants as a treatment option are proposed, and recommended guidelines for the successful delivery of immediately loaded implants in the maxilla are presented.

Cell-Free Synthetic Glycobiology: Designing and Engineering Glycomolecules Outside of Living Cells.

Glycans and glycosylated biomolecules are directly involved in almost every biological process as well as the etiology of most major diseases. Hence, glycoscience knowledge is essential to efforts aimed at addressing fundamental challenges in understanding and improving human health, protecting the environment and enhancing energy security, and developing renewable and sustainable resources that can serve as the source of next-generation materials. While much progress has been made, there remains an urgent need for new tools that can overexpress structurally uniform glycans and glycoconjugates in the quantities needed for characterization and that can be used to mechanistically dissect the enzymatic reactions and multi-enzyme assembly lines that promote their construction. To address this technology gap, cell-free synthetic glycobiology has emerged as a simplified and highly modular framework to investigate, prototype, and engineer pathways for glycan biosynthesis and biomolecule glycosylation outside the confines of living cells. From nucleotide sugars to complex glycoproteins, we summarize here recent efforts that harness the power of cell-free approaches to design, build, test, and utilize glyco-enzyme reaction networks that produce desired glycomolecules in a predictable and controllable manner. We also highlight novel cell-free methods for shedding light on poorly understood aspects of diverse glycosylation processes and engineering these processes toward desired outcomes. Taken together, cell-free synthetic glycobiology represents a promising set of tools and techniques for accelerating basic glycoscience research (e.g., deciphering the "glycan code") and its application (e.g., biomanufacturing high-value glycomolecules on demand).

Oncogenic role of microRNAs in brain tumors.

MicroRNAs (miRNAs) are short non-protein-coding RNAs that function as key regulators of diverse biological processes through negative control on gene expression at the post-transcriptional level. Emerging evidence indicates that miRNAs play an important role in the development of human cancers, with their deregulation resulting in altered activity of downstream tumor suppressors, oncogenes and other signaling molecules. Recent years have seen considerable progress in miRNA research in brain tumors, particularly in glioblastomas and medulloblastomas, providing novel insights into the pathogenesis of these malignant lesions. Expression profiling has unveiled miRNA signatures that not only distinguish brain tumors from normal tissues, but can also differentiate histotypes or molecular subtypes with altered genetic pathways. Moreover, specific miRNA subsets may have potential diagnostic and prognostic values in some brain tumors. Several deregulated miRNAs uncovered in glioblastomas and medulloblastomas have their gene targets and the associated genetic pathways identified. This review summarizes recent findings of miRNA study in brain tumors.

Identification of a region of homozygous deletion on 8p22-23.1 in medulloblastoma.

To identify critical tumor suppressor loci that are associated with the development of medulloblastoma, we performed a comprehensive genome-wide allelotype analysis in a series of 12 medulloblastomas. Non-random allelic imbalances were identified on chromosomes 7q (58.3%), 8p (66.7%), 16q (58.3%), 17p (58.3%) and 17q (66.7%). Comparative genomic hybridization analysis confirmed that allelic imbalances on 8p, 16q and 17p were due to loss of genetic materials. Finer deletion mapping in an expanded series of 23 medulloblastomas localized the common deletion region on 8p to an interval of 18.14 cM on 8p22-23.2. We then searched within the region of loss on 8p for loci that might contain homozygous deletion using comparative duplex PCR. An overlapping homozygous deletion region was identified in a 1.8 cM interval on 8p22-23.1, between markers D8S520 and D8S1130, in two medulloblastomas. This region of homozygous deletion also encompasses the 1.4 cM minimal deletion region detected on 8p in ductal carcinoma in situ of breast. In conclusion, we reported for the first time a detailed deletion mapping on 8p in medulloblastoma and have identified a region of homozygous deletion on 8p22-23.1 that is likely to contain a critical tumor suppressor gene involved in the development of medulloblastoma.

Aberrant CpG island hypermethylation profile is associated with atypical and anaplastic meningiomas.

Hypermethylation of promoter CpG islands is a common epigenetic event in a variety of human cancers. The aim of this study was to investigate whether promoter hypermethylation of cancer-related genes is involved in the development and progression of meningiomas. The methylation status at the promoter region of 10 cancer-related genes was examined by methylation-specific polymerase chain reaction in a cohort of 48 meningiomas including 16 benign, 19 atypical, and 13 anaplastic variants. The relationship of promoter hypermethylation and transcriptional silencing was determined by treatment of cells with demethylating agent 5-aza-2'-deoxycytidine followed by reverse transcription-polymerase chain reaction. Our results showed that 50% (24/48) of meningiomas exhibited promoter hypermethylation in at least one of the genes but not in normal leptomeninges, indicating that aberrant hypermethylation is tumor-specific. Promoter hypermethylation was detected in glutathione S -transferases P1 at 27%, thrombospondin-1 at 15%, retinoblastoma 1 at 10%, cyclin-dependent kinase inhibitor 2A at 10%, O 6 -methylguanine-DNA methyltransferase at 6%, and death-associated protein kinase 1, von Hippel-Lindau, p14 ARF , and cyclin-dependent kinase inhibitor 2B, each at 4%. No promoter hypermethylation was detected in the tissue inhibitor of metalloproteinase 3 gene. Treatment of IOMM-Lee meningioma cell line with 5-aza-2'-deoxycytidine restored expression of O 6 -methylguanine-DNA methyltransferase and death-associated protein kinase 1, providing evidence that promoter hypermethylation contributes to transcriptional silencing. The frequencies of methylation of any single gene in benign, atypical, and malignant meningiomas were 6% (1/16), 74% (14/19), and 69% (9/13), respectively. Of 48 tumors, 13 (27%) showed that concurrent hypermethylation of two or more genes studied were of atypical or anaplastic type. Statistical analysis revealed that the incidence of promoter hypermethylation of any single gene, of multiple genes, or of glutathione S -transferase P1 was significantly associated with atypical and anaplastic meningiomas ( P < .0001, P = .004, and P = .004, respectively). In conclusion, this study demonstrates that aberrant hypermethylation profile is associated with atypical and anaplastic meningiomas, suggesting that epigenetic change may be involved in malignant progression of meningiomas.

Epigenetic inactivation of DLC-1 in supratentorial primitive neuroectodermal tumor.

Supratentorial primitive neuroectodermal tumors (SPNETs) and medulloblastomas (MBs) are histologically similar intracranial tumors found in different anatomic locations of the brain. Our group has previously demonstrated that loss of chromosome 8p is a frequent event in MBs. The aim of this study was to evaluate whether DLC-1, a newly identified tumor-suppressor gene on chromosome 8p22, is involved in the tumorigenesis of MBs and the histologically similar SPNETs. We first assessed for alterations of gene expression in microdissected tumors and detected lack of DLC-1 transcript in 1 of 9 MBs (case M44) and 1 of 3 SPNETs (case M1). Neither somatic base substitutions nor homozygous deletion were found in tumors without DLC-1 transcript. We then explored the possibility of hypermethylation of the CpG island in DLC-1 as the mechanism of suppressed expression. Methylation-specific polymerase chain reaction revealed promotor hypermethylation of DLC-1 in M1 but not in M44. Bisulfite sequencing further verified a densely methylated pattern of 35 CpG sites studied in M1 that were not found in normal brain, indicating that inactivation of DLC-1 by hypermethylation is involved in SPNET. Based on this finding, we examined an additional 20 MBs, 8 SPNETs, and 4 MB and 2 SPNET cell lines for hypermethylation of the CpG island of DLC-1, finding that none of these samples exhibited DLC-1 methylation. In conclusion, our results demonstrate that transcriptional silencing of DLC-1 through promoter hypermethylation may contribute to tumorigenesis in a subset of SPNETs, and that loss of DLC-1 expression in MBs may be related to mechanisms other than promoter hypermethylation, genomic deletion, and mutation.

Promoter hypermethylation profile of RASSF1A, FHIT, and sFRP1 in intracranial primitive neuroectodermal tumors.

Medulloblastomas (MBs) and supratentorial primitive neuroectodermal tumors (SPNETs) are histologically alike intracranial PNETs found in different anatomical locations of the brain. Current evidence suggests that hypermethylation of promoter CpG islands is a common epigenetic event in a variety of human cancers. The aim of this study was to investigate whether promoter hypermethylation of putative tumor suppressor genes was involved in both types of intracranial PNETs. We examined the methylation status at promoter regions of RASSF1A, FHIT, and sFRP1 by methylation-specific polymerase chain reaction in a cohort of 25 primary MBs, 9 primary SPNETs, and 3 MB and 2 SPNET cell lines. Our results revealed no promoter hypermethylation of RASSF1A, FHIT, and sFRP1 in 2 normal cerebellar and 5 normal cerebral tissue specimens examined. In contrast, promoter hypermethylation of RASSF1A was detected in 100% of primary MBs, 67% (6/9) of primary SPNETs, and all PNET cell lines. The frequency of promoter hypermethylation of RASSF1A was significantly lower in SPNETs than in MBs (Fisher exact test, P = .014). Treatment of RASSF1A-deficient PNET cell lines with 5-aza-2'deoxycytidine, a demethylating agent, restored RASSF1A expression, providing evidence that promoter hypermethylation contributes to transcriptional silencing. In addition, promoter hypermethylation of FHIT and sFRP1 was detected in 22% (2/9) and 11% (1/9) of SPNETs, respectively, but not in any MBs studied. In conclusion, our study demonstrates that promoter hypermethylation of RASSF1A is a common event in intracranial PNETs, whereas FHIT and sFRP1 are epigenetically affected in a fraction of SPNETs.

Clonality of oligoastrocytomas.

Oligoastrocytomas (OA) are mixed glial tumors that show morphologic features of both oligodendrogliomas and astrocytomas. The histogenesis of these tumors remains undefined. The aim of this study was to investigate the clonality of OA on the basis of tumor-dependent genetic alterations and tumor-independent X-chromosome inactivation. We microdissected 11 biphasic OA and subjected the oligodendroglial and astrocytic components to allelic loss analysis of chromosomes 1p, 9p21, 10q, 13q, 17p, and 19q; TP53 immunohistochemical and mutation analyses; and X-linked HUMARA gene methylation study. On the basis of the genetic findings, we categorized these tumors into 3 groups. Group 1 consisted of 4 tumors that showed identical genetic aberrations in the 2 histologic elements, characterized by allelic loss on 1p and 19q. These results suggest that group 1 tumors are of monoclonal origin and share a precursor cell with oligodendrogliomas. Group 2 consisted of 5 tumors characterized by losses on 1p and 19q, with additional allelic losses on chromosomes 9p, 10q, 13q and/or 17p. Four of these tumors were of the anaplastic type. Thus, group 2 tumors may be regarded as advanced variants of group 1 OA with heterogeneous genetic changes during clonal expansion. The X-chromosome inactivation analysis confirmed the monoclonality of groups 1 and 2 OA. Group 3 consisted of two tumors that showed divergent allelic loss patterns in the 2 histologic components. Mutation and overexpression of TP53 were detectable in the astrocytic components only. These findings raise the possibility that group 3 tumors have a biclonal origin. In conclusion, our results suggest that OA are predominantly of monoclonal origin but that a small subset of tumors may be derived from different precursors.

Genome-wide survey for chromosomal imbalances in ganglioglioma using comparative genomic hybridization.

Ganglioglioma is a mixed neuronal and glial tumor first described by Perkin in 1926. Because of its rare occurrence in the central nervous system, the pathogenesis of this neoplasm is still largely unknown. Previous studies of ganglioglioma mainly focused on histologic features, immunohistochemical analysis, clinical treatment, and patient outcome. Very few cytogenetic and molecular genetic studies have been reported on this neoplasm. To better understand the mechanism underlying the development of ganglioglioma, we performed comparative genomic hybridization analysis to investigate chromosomal imbalances across the entire genome in five cases of gangliogliomas. Loss of genetic material on the short arm of chromosome 9 was a common genetic alteration found in three of five cases. Overrepresentation of partial or the whole chromosome 7 was another recurrent chromosomal imbalance, confirmed by fluorescence in situ hybridization. Immunohistochemical analysis was performed; all five cases revealed no reaction or low expression for epidermal growth factor receptor antibody. Our study highlights chromosomal regions for further fine mapping and investigation of candidate tumor suppressor genes involved in the pathogenesis of ganglioglioma.

Low-density lipoprotein receptor-related protein 8 (apolipoprotein E receptor 2) gene polymorphisms in Alzheimer's disease.

Apolipoprotein E (ApoE) isoforms affect the risk of developing Alzheimer's disease (AD). ApoE-associated risk may be related to its binding to and clearance by cell surface receptors, such as the members of the low-density lipoprotein (LDL) receptor family. Previous studies had shown association of LDL receptor-related protein (LRP) and AD, therefore we speculated that another member of this LDL receptor family, LRP8 (also called apolipoprotein E receptor 2 or ApoER2), which is predominantly expressed in brain, might be associated with Alzheimer's disease. To explore this hypothesis, we screened exons 2-19 of the LRP8 gene in a total of 204 AD and 184 elderly control subjects for polymorphisms using the conformation-sensitive gel electrophoresis method. Our results revealed four sequence alterations: two predicted to result in amino acid changes (E46D and R952Q), one in an intron (IVS9 + 7G > A), and one synonymous polymorphism (2622T > C). The latter was found in four AD patients (2.0%) and 11 controls (6.0%), a significant difference (P = 0.042). Further study is needed to confirm this possible association of LRP8 with AD.

[Genome-wide genetic study of medulloblastoma using allelotype analysis].

OBJECTIVE: To investigate global genetic alterations in medulloblastoma, and to localize critical chromosomal loci with allelic imbalances associated with the development of medulloblastoma. METHODS: A high-resolution genome-wide allelotype analysis, including 384 microsatellite markers, was performed in 12 medulloblastomas. RESULTS: An average of 238 (62.3%) allelic imbalances were detected on all 39 autosomal arms. Non-random allelic gains or losses were detected on chromosomes 7q (58.3%), 8p (66.7%), 16q (58.3%), 17p (58.3%) and 17q (66.7%). In addition, chromosomal arms with frequencies of allelic imbalances higher than the mean percentage were identified on 3p (33.3%), 3q (33.3%), 4q (41.7%), 7p (33.3%), 8q (41.7%), 10q (41.7%), 13q (33.3%), 14q (33.3%) and 20q (33.3%). No relationship was found between the frequency of allelic imbalances and the clinical outcome of the patients. CONCLUSIONS: A global view of the genetic alterations in medulloblastoma was provided. The allelic imbalances involving chromosomes 7q, 8p, 16q, 17p and 17q may play an important role in the pathogenesis of medulloblastoma.

[Mechanism of antisense epidermal growth factor receptor cDNA in growth suppression of glioblastomas cells].

OBJECTIVE: To study the mechanism of antisense epidermal growth factor receptor cDNA in growth suppression of glioblastomas cells. METHODS: Glioblastoma U87MG cells, which over-express epidermal growth factor receptor (EGFR), were transfected with antisense-EGFR constructs. Several clones with stable expression of lower or undetectable levels of EGFR protein were obtained. The effect of antisense-EGFR on cell differentiation was studied using morphological evaluation and western blotting analysis of glial fibrillary acidic protein (GFAP) expression. The effect of antisense-EGFR on cell cycle was studied by flow cytometry and immunohistochemical analysis of p53, Rb, p16 and CDK4 expressions. The effect of antisense-EGFR on telomerase activity was studied by telomeric repeat amplification protocol (TRAP) assay. RESULTS: U87MG cells that were transfected with antisense-EGFR constructs had smaller cell bodies and longer processes, and expressed higher level of GFAP compared with that of the control cells. Flow cytometric analysis showed that the proportion of cells in G(0)/G(1) phases of the cell cycle in the antisense EGFR cDNA transfected clones increased significantly when compared with control cells, whereas the proportion of cells in S phase decreased markedly. In addition, immunohistochemical analysis showed that the expression of wild-type p53 was significantly increased in the antisense-EGFR cDNA transfected clones, whereas the expressions of Rb, p16 and CDK4 were not altered. TRAP assay revealed that telomerase activity in the antisense-EGFR clones was significantly decreased. CONCLUSIONS: Antisense-EGFR transfection inhibits U87MG cell growth by inducing cell differentiation and p53 expression, G(1) cell cycle arrest and inhibition of telomerase activity.

[The effects of wild-type PTEN transfection on gene expressions of glioblastomas].

OBJECTIVE: To study the effects of wild-type PTEN on gene expressions of glioblastomas. METHODS: Glioblastoma U87MG cells, which express inactivated PTEN, were transfected with wild-type PTEN constructs and stable transfected clones were selected. Then, cDNA microarray analyses were used to identify differentially expressed genes in wild-type PTEN transfected cells and control cells. RESULTS: Transfected wild-type PTEN inhibited the proliferation of U87MG. By cDNA microarray analyses, 89 cDNA clones were identified, which were differentially expressed in wild-type PTEN transfected cells and control cells. Among these genes, 13 genes were unknown and 76 genes were known genes, including glial fibrillary acidic protein, p21/WAF1, human TGF-beta inducible early protein, human DNA fragmentation factor 45 etc. CONCLUSION: Wild-type PTEN can affect the expressions of multiple genes, by which it regulates the proliferation, differentiation and apoptosis of glioblastomas.

MiR-22 is frequently downregulated in medulloblastomas and inhibits cell proliferation via the novel target PAPST1.

Medulloblastoma is the most frequent malignant central nervous system tumor in children. MicroRNAs (miRs) are small, non-coding RNAs that target protein-coding and non-coding RNAs, and play roles in a variety of cellular processes through regulation of multiple targets. In the present study, we analyzed miR-22 expression and its effect in cell proliferation and apoptosis in medulloblastomas. Quantitative reverse transcription PCR (RT-PCR) revealed significantly lower expression of miR-22 in 19 out of 27 (70%) medulloblastomas, D341, DAOY, ONS-76 medulloblastoma cell lines, compared with normal cerebellum. Forced expression of miR-22 by lentiviral vector transfection reduced cell proliferation and induced apoptosis, while knockdown of miR-22 increased proliferative activity in DAOY and ONS-76 cells. DAOY cells with miR-22 overexpression in nude mice yielded tumors smaller than those originated from control DAOY cells. Microarray analysis in DAOY cells with forced miR-22 expression showed significant changes in expression profiles, PAPST1 being the most significantly (10 folds) downregulated gene. Quantitative RT-PCR revealed PAPST1 mRNA upregulation in 18 out of 27 (67%) medulloblastomas. In addition, a luciferase reporter assay in ONS-76 and DAOY cells suggested that miR-22 directly targets the PAPST1 gene, and lentivirus-mediated knockdown of PAPST1 suppressed proliferation of DAOY and ONS-76 medulloblastoma cells. These results suggest that frequently downregulated miR-22 expression is associated with cell proliferation in medulloblastomas, and this may be at least in part via PAPST1, which is a novel target of miR-22.

MiR-383 is downregulated in medulloblastoma and targets peroxiredoxin 3 (PRDX3).

Accumulating evidence suggests that microRNAs (miRNAs) are over- or under-expressed in tumors, and abnormalities in miRNA expression may contribute to carcinogenesis. MiR-383 was previously identified as one of the under-expressed miRNAs in medulloblastoma (MB) by miRNA expression profiling. Quantitative reverse transcription polymerase chain reaction (RT-PCR)-based miRNA assays showed an enrichment of miR-383 in normal brain. Based on these data, we speculated that miR-383 is important in MB pathogenesis. In this study, we demonstrated significant downregulation of miR-383 in 23/29 (79%) MB samples and 7/7 (100%) MB cells lines. Ectopic expression of miR-383 in MB cells led to suppression of cell growth, cell accumulation at sub-G1 phase and alteration of apoptosis-related proteins. By transcriptomic analysis and computational algorithms, we identified peroxiredoxin 3 (PRDX3) as a target gene of miR-383. Luciferase reporter assay confirmed that miR-383 negatively regulated PRDX3 by interaction between miR-383 and complementary sequences in the 3' UTR of PRDX3. MiR-383 repressed PRDX3 at transcriptional and translational levels as revealed by quantitative RT-PCR and Western blot analysis. Furthermore, depletion of PRDX3 by siRNAs resulted in similar effects as observed in miR-383-transfected cells. In conclusion, miR-383 acts as a regulator controlling cell growth of MB, at least in part, through targeting PRDX3.