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1.
Nat Commun ; 14(1): 3704, 2023 Jun 22.
Article in English | MEDLINE | ID: mdl-37349307

ABSTRACT

At seasonal-to-interannual timescales, Atlantic hurricane activity is greatly modulated by El Niño-Southern Oscillation and the Atlantic Meridional Mode. However, those climate modes develop predominantly in boreal winter or spring and are weaker during the Atlantic hurricane season (June-November). The leading mode of tropical Atlantic sea surface temperature (SST) variability during the Atlantic hurricane season is Atlantic Niño/Niña, which is characterized by warm/cold SST anomalies in the eastern equatorial Atlantic. However, the linkage between Atlantic Niño/Niña and hurricane activity has not been examined. Here, we use observations to show that Atlantic Niño, by strengthening the Atlantic inter-tropical convergence zone rainband, enhances African easterly wave activity and low-level cyclonic vorticity across the deep tropical eastern North Atlantic. We show that such conditions increase the likelihood of powerful hurricanes developing in the deep tropics near the Cape Verde islands, elevating the risk of major hurricanes impacting the Caribbean islands and the U.S.


Subject(s)
Cyclonic Storms , Cabo Verde , Temperature , Seasons , El Nino-Southern Oscillation
2.
Q J R Meteorol Soc ; 148(749): 3639-3659, 2022 Oct.
Article in English | MEDLINE | ID: mdl-37063171

ABSTRACT

This study uses a coupled atmosphere-ocean model with different numerical settings to investigate the mean and eddy momentum transfer processes responsible for Typhoon Muifa's (2011) early rapid intensification (RI). Three experiments are conducted. Two use the coupled model with a horizontal resolution of either 1 km (HRL) or 3 km (LRL). The third (NoTCFB) is the same as LRL but excludes tropical cyclone (TC)-induced sea-surface temperature (SST) cooling. HRL reasonably reproduces Muifa's intensity during its rapid intensification and weakening periods. The azimuthal mean tangential and radial momentum budgets are analysed before the RI rates diverge between HRL and LRL. Results show that the dominant processes responsible for Muifa's intensification are different in HRL and LRL. For HRL, the net eddy effect intensifies the storm's circulation and contracts the eyewall during early RI, and it dominates the net mean-flow effect inside the radius of maximum wind (RMW), except near the surface and between 2 and 5 km close to the RMW. In contrast, the mean and eddy effects in LRL almost cancel inside the RMW, while the mean-flow effects dominate and intensify tangential winds outside. Without TC-induced SST cooling, Muifa in NoTCFB reaches a similar storm intensity as in HRL but its rapid weakening rate is substantially underestimated. The dominant mechanisms for tangential wind intensification in NoTCFB are similar to those in LRL, but their magnitudes are larger, implying a misrepresentation of the dominant momentum transfer processes in NoTCFB during RI. For the radial momentum budget analysis, the dominant processes are similar among the three experiments except for some differences in their locations and strengths.

3.
Nat Commun ; 11(1): 3829, 2020 07 31.
Article in English | MEDLINE | ID: mdl-32737290

ABSTRACT

The direct response of the tropical mixed layer to near-inertial waves (NIWs) has only rarely been observed. Here, we present upper-ocean turbulence data that provide evidence for a strongly elevated vertical diffusive heat flux across the base of the mixed layer in the presence of a NIW, thereby cooling the mixed layer at a rate of 244 W m-2 over the 20 h of continuous measurements. We investigate the seasonal cycle of strong NIW events and find that despite their local intermittent nature, they occur preferentially during boreal summer, presumably associated with the passage of atmospheric African Easterly Waves. We illustrate the impact of these rare but intense NIW induced mixing events on the mixed layer heat balance, highlight their contribution to the seasonal evolution of sea surface temperature, and discuss their potential impact on biological productivity in the tropical North Atlantic.

4.
Ann N Y Acad Sci ; 1472(1): 21-48, 2020 07.
Article in English | MEDLINE | ID: mdl-32223020

ABSTRACT

Despite a globally uniform increase in the concentrations of emitted greenhouse gases, radiatively forced surface warming can have significant spatial variations. These define warming patterns that depend on preexisting climate states and through atmospheric and oceanic dynamics can drive changes of the hydrological cycle with global-scale feedbacks. Our study reviews research progress on the hydrological cycle changes and their effects on multiscale climate variability. Overall, interannual variability is expected to become stronger in the Pacific and Indian Oceans and weaker in the Atlantic. Global monsoon rainfall is projected to increase and the wet season to lengthen despite a slowdown of atmospheric circulation. Strong variations among monsoon regions are likely to emerge, depending on surface conditions such as orography and land-sea contrast. Interdecadal climate variability is expected to modulate the globally averaged surface temperature change with pronounced anomalies in the polar and equatorial regions, leading to prolonged periods of enhanced or reduced warming. It is emphasized that advanced global observations, regional simulations, and process-level investigations are essential for improvements in understanding, predicting, and projecting the modes of climate variability, monsoon sensitivity, and energetic fluctuations in a warming climate.


Subject(s)
Climate Change , Global Warming , Models, Theoretical , Oceans and Seas , Seasons
5.
J Neurosurg ; 126(4): 1220-1226, 2017 Apr.
Article in English | MEDLINE | ID: mdl-27285539

ABSTRACT

OBJECTIVE Microcystic meningioma (MM) is a meningioma variant with a multicystic appearance that may mimic intrinsic primary brain tumors and other nonmeningiomatous tumor types. Dynamic susceptibility contrast (DSC) and dynamic contrast-enhanced (DCE) MRI techniques provide imaging parameters that can differentiate these tumors according to hemodynamic and permeability characteristics with the potential to aid in preoperative identification of tumor type. METHODS The medical data of 18 patients with a histopathological diagnosis of MM were identified through a retrospective review of procedures performed between 2008 and 2012; DSC imaging data were available for 12 patients and DCE imaging data for 6. A subcohort of 12 patients with Grade I meningiomas (i.e., of meningoepithelial subtype) and 54 patients with Grade IV primary gliomas (i.e., astrocytomas) was also included, and all preoperative imaging sequences were analyzed. Clinical variables including patient sex, age, and surgical blood loss were also included in the analysis. Images were acquired at both 1.5 and 3.0 T. The DSC images were acquired at a temporal resolution of either 1500 msec (3.0 T) or 2000 msec (1.5 T). In all cases, parameters including normalized cerebral blood volume (CBV) and transfer coefficient (kTrans) were calculated with region-of-interest analysis of enhancing tumor volume. The normalized CBV and kTrans data from the patient groups were analyzed with 1-way ANOVA, and post hoc statistical comparisons among groups were conducted with the Bonferroni adjustment. RESULTS Preoperative DSC imaging indicated mean (± SD) normalized CBVs of 5.7 ± 2.2 ml for WHO Grade I meningiomas of the meningoepithelial subtype (n = 12), 4.8 ± 1.8 ml for Grade IV astrocytomas (n = 54), and 12.3 ± 3.8 ml for Grade I meningiomas of the MM subtype (n = 12). The normalized CBV measured within the enhancing portion of the tumor was significantly higher in the MM subtype than in typical meningiomas and Grade IV astrocytomas (p < 0.001 for both). Preoperative DCE imaging indicated mean kTrans values of 0.49 ± 0.20 min-1 in Grade I meningiomas of the meningoepithelial subtype (n = 12), 0.27 ± 0.12 min-1 for Grade IV astrocytomas (n = 54), and 1.35 ± 0.74 min-1 for Grade I meningiomas of the MM subtype (n = 6). The kTrans was significantly higher in the MM variants than in the corresponding nonmicrocystic Grade 1 meningiomas and Grade IV astrocytomas (p < 0.001 for both). Intraoperative blood loss tended to increase with increased normalized CBV (R = 0.45, p = 0.085). CONCLUSIONS An enhancing cystic lesion with a normalized CBV greater than 10.3 ml or a kTrans greater than 0.88 min-1 should prompt radiologists and surgeons to consider the diagnosis of MM rather than traditional Grade I meningioma or high-grade glioma in planning surgical care. Higher normalized CBVs tend to be associated with increased intraoperative blood loss.


Subject(s)
Brain Neoplasms/diagnostic imaging , Brain/diagnostic imaging , Glioma/diagnostic imaging , Magnetic Resonance Imaging , Meningeal Neoplasms/diagnostic imaging , Meningioma/diagnostic imaging , Brain Neoplasms/pathology , Cohort Studies , Diagnosis, Differential , Female , Glioma/pathology , Humans , Image Interpretation, Computer-Assisted , Magnetic Resonance Imaging/methods , Male , Meningeal Neoplasms/pathology , Meningioma/pathology , Middle Aged , Neoplasm Grading
6.
Nat Commun ; 7: 13670, 2016 11 25.
Article in English | MEDLINE | ID: mdl-27886199

ABSTRACT

Super typhoons (STYs), intense tropical cyclones of the western North Pacific, rank among the most destructive natural hazards globally. The violent winds of these storms induce deep mixing of the upper ocean, resulting in strong sea surface cooling and making STYs highly sensitive to ocean density stratification. Although a few studies examined the potential impacts of changes in ocean thermal structure on future tropical cyclones, they did not take into account changes in near-surface salinity. Here, using a combination of observations and coupled climate model simulations, we show that freshening of the upper ocean, caused by greater rainfall in places where typhoons form, tends to intensify STYs by reducing their ability to cool the upper ocean. We further demonstrate that the strengthening effect of this freshening over the period 1961-2008 is ∼53% stronger than the suppressive effect of temperature, whereas under twenty-first century projections, the positive effect of salinity is about half of the negative effect of ocean temperature changes.

7.
Oncotarget ; 6(7): 5369-81, 2015 Mar 10.
Article in English | MEDLINE | ID: mdl-25749033

ABSTRACT

Epigenetic changes, including H3K4me3 and H3K27me3 histone modification, play an important role in carcinogenesis. However, no genome-wide histone modification map has been generated for gliomas. Here, we report a genome-wide map of H3K4me3 and H3K27me3 histone modifications for 8 glioma stem cell (GSC) lines, together with the associated gene activation or repression patterns. In addition, we compared the genome-wide histone modification maps of GSC lines to those of astrocytes to identify unique gene activation or repression profiles in GSCs and astrocytes. We also identified a set of bivalent genes, which are genes that are associated with both H3K4me3 and H3K27me3 marks and are poised for action in embryonic stem cells. These bivalent genes are potential targets for inducing differentiation in glioblastoma (GBM) as a therapeutic approach. Finally, we identified SLC17A7 as a bivalent tumor suppressor gene in GBM, as it is down-regulated at both the protein and RNA levels in GBM tissues compared with normal brain tissues, and it inhibits GBM cell proliferation, migration and invasion.


Subject(s)
Chromatin/genetics , Genes, Tumor Suppressor , Glioblastoma/genetics , Glioblastoma/pathology , Histones/genetics , Neoplastic Stem Cells/pathology , Vesicular Glutamate Transport Protein 1/genetics , Apoptosis , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Blotting, Western , Cell Differentiation , Cell Movement , Cell Proliferation , Chromatin Immunoprecipitation , Epigenesis, Genetic , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Genome, Human , Glioblastoma/metabolism , Humans , Neoplastic Stem Cells/metabolism , Oligonucleotide Array Sequence Analysis , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Tumor Cells, Cultured , Vesicular Glutamate Transport Protein 1/metabolism
8.
Cancer Lett ; 360(1): 60-7, 2015 Apr 28.
Article in English | MEDLINE | ID: mdl-25676691

ABSTRACT

The failure of standard treatment for patients diagnosed with glioblastoma (GBM) coupled with the highly vascularized nature of this solid tumor has led to the consideration of agents targeting VEGF or VEGFRs, as alternative therapeutic strategies for this disease. Despite modest achievements in survival obtained with such treatments, failure to maintain an enduring survival benefit and more invasive relapsing tumors are evident. Our study suggests a potential mechanism by which anti-VEGF/VEGFR therapies regulate the enhanced invasive phenotype through a pathway that involves TGFßR and CXCR4. VEGFR signaling inhibitors (Cediranib and Vandetanib) elevated the expression of CXCR4 in VEGFR-expressing GBM cell lines and tumors, and enhanced the in vitro migration of these lines toward CXCL12. The combination of VEGFR inhibitor and CXCR4 antagonist provided a greater survival benefit to tumor-bearing animals. The upregulation of CXCR4 by VEGFR inhibitors was dependent on TGFß/TGFßR, but not HGF/MET, signaling activity, suggesting a mechanism of crosstalk among VEGF/VEGFR, TGFß/TGFßR, and CXCL12/CXCR4 pathways in the malignant phenotype of recurrent tumors after anti-VEGF/VEGFR therapies. Thus, the combination of VEGFR, CXCR4, and TGFßR inhibitors could provide an alternative strategy to halt GBM progression.


Subject(s)
Angiogenesis Inhibitors/pharmacology , Brain Neoplasms/drug therapy , Glioblastoma/drug therapy , Piperidines/pharmacology , Protein Kinase Inhibitors/pharmacology , Quinazolines/pharmacology , Receptors, CXCR4/metabolism , Receptors, Transforming Growth Factor beta/metabolism , Receptors, Vascular Endothelial Growth Factor/antagonists & inhibitors , Signal Transduction/drug effects , Adult , Aged , Animals , Benzylamines , Brain Neoplasms/enzymology , Brain Neoplasms/genetics , Brain Neoplasms/pathology , Cell Line, Tumor , Cell Movement/drug effects , Cyclams , Female , Glioblastoma/enzymology , Glioblastoma/genetics , Glioblastoma/pathology , Heterocyclic Compounds/pharmacology , Humans , Interleukin-2 Receptor alpha Subunit/deficiency , Interleukin-2 Receptor alpha Subunit/genetics , Male , Mice, Inbred NOD , Mice, Knockout , Mice, SCID , Middle Aged , Neoplasm Invasiveness , Receptor Cross-Talk/drug effects , Receptors, CXCR4/antagonists & inhibitors , Receptors, Vascular Endothelial Growth Factor/metabolism , Time Factors , Up-Regulation , Xenograft Model Antitumor Assays
9.
Oncol Rep ; 31(5): 2261-9, 2014 May.
Article in English | MEDLINE | ID: mdl-24604520

ABSTRACT

MicroRNAs (miRNAs) are small non-coding RNAs of 20-25 nucleotides in length that are capable of modulating gene expression post-transcriptionally. The potential roles of miRNAs in the tumorigenesis of glioblastoma (GBM) have been under intensive studies in the past few years. In the present study, we found a positive correlation between the levels of miR-127-3p and the cell migration and invasion abilities in several human GBM cell lines. We showed that miR-127-3p promoted cell migration and invasion of GBM cells using in vitro cell lines and in vivo mouse models. We identified SEPT7, a known tumor-suppressor gene that has been reported to suppress GBM cell migration and invasion, as a direct target of miR-127-3p. SEPT7 was able to partially abrogate the effect of miR-127-3p on cell migration and invasion. In addition, microarray analysis revealed that miR-127-3p regulated a number of migration and invasion-related genes. Finally, we verified that miR-127-3p affected the remodeling of the actin cytoskeleton mediated by SEPT7 in GBM cells.


Subject(s)
Cell Cycle Proteins/genetics , Cell Movement/genetics , Glioblastoma/pathology , MicroRNAs/genetics , Septins/genetics , Actin Cytoskeleton/genetics , Actin Cytoskeleton/metabolism , Animals , Cell Line, Tumor , Cell Proliferation , Cell Transformation, Neoplastic/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Mice , Mice, Nude , MicroRNAs/biosynthesis , Neoplasm Invasiveness/genetics , Neoplasm Invasiveness/pathology
10.
Brief Bioinform ; 15(2): 244-55, 2014 Mar.
Article in English | MEDLINE | ID: mdl-23818492

ABSTRACT

Distinguishing driver mutations from passenger mutations is critical to the understanding of the molecular mechanisms of carcinogenesis and for identifying prognostic and diagnostic markers as well as therapeutic targets. We reviewed the current approaches and software for identifying driver mutations from passenger mutations including both biology-based approaches and machine-learning-based approaches. We also reviewed approaches to identify driver mutations in the context of pathways or gene sets. Finally, we discussed the challenges of predicting driver mutations considering the complexities of inter- and intra-tumor heterogeneity as well as the evolution and progression of tumors.


Subject(s)
Mutation , Neoplasms/genetics , Algorithms , Artificial Intelligence , Computational Biology/methods , DNA Mutational Analysis/statistics & numerical data , High-Throughput Nucleotide Sequencing/statistics & numerical data , Humans , Likelihood Functions , Polymorphism, Single Nucleotide , Precision Medicine , Software
11.
PLoS One ; 8(3): e59750, 2013.
Article in English | MEDLINE | ID: mdl-23555768

ABSTRACT

Glioblastoma (GBM) is the most common primary brain tumor in adults. The poor prognosis and minimally successful treatments of these tumors indicates a need to identify new therapeutic targets. Therapy resistance of GBMs is attributed to heterogeneity of the glioblastoma due to genetic alterations and functional subpopulations. Chemokine receptors CXCR4 and CXCR7 play important roles in progression of various cancers although the specific functions of the CXCL12-CXCR4-CXCR7 axis in GBM are less characterized. In this study we examined the expression and function of CXCR4 and CXCR7 in four primary patient-derived GBM cell lines of the proliferative subclass, investigating their roles in in vitro growth, migration, sphere and tube formation. CXCR4 and CXCR7 cell surface expression was heterogeneous both between and within each cell line examined, which was not reflected by RT-PCR analysis. Variable percentages of CXCR4+CXCR7- (CXCR4 single positive), CXCR4-CXCR7+ (CXCR7 single positive), CXCR4+CXCR7+ (double positive), and CXCR4-CXCR7- (double negative) subpopulations were evident across the lines examined. A subpopulation of slow cell cycling cells was enriched in CXCR4 and CXCR7. CXCR4+, CXCR7+, and CXCR4+/CXCR7+ subpopulations were able to initiate intracranial tumors in vivo. CXCL12 stimulated in vitro cell growth, migration, sphere formation and tube formation in some lines and, depending on the response, the effects were mediated by either CXCR4 or CXCR7. Collectively, our results indicate a high level of heterogeneity in both the surface expression and functions of CXCR4 and CXCR7 in primary human GBM cells of the proliferative subclass. Should targeting of CXCR4 and CXCR7 provide clinical benefits to GBM patients, a personalized treatment approach should be considered given the differential expression and functions of these receptors in GBM.


Subject(s)
Brain Neoplasms/metabolism , Gene Expression Regulation, Neoplastic , Glioblastoma/metabolism , Receptors, CXCR4/metabolism , Receptors, CXCR/metabolism , Animals , Apoptosis , Cell Membrane/metabolism , Cell Movement , Cell Proliferation , Chemokine CXCL12/pharmacology , Flow Cytometry , Gene Expression Profiling , Humans , Immunohistochemistry , Mice , Mice, Inbred NOD , Mice, SCID
12.
OMICS ; 17(3): 136-49, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23421905

ABSTRACT

Alternative polyadenylation (APA) is widely present in the human genome and plays a key role in carcinogenesis. We conducted a comprehensive analysis of the APA products in glioblastoma multiforme (GBM, one of the most lethal brain tumors) and normal brain tissues and further developed a computational pipeline, RNAelements (http://sysbio.zju.edu.cn/RNAelements/), using covariance model from known RNA binding protein (RBP) targets acquired by RNA Immunoprecipitation (RIP) analysis. We identified 4530 APA isoforms for 2733 genes in GBM, and found that 182 APA isoforms from 148 genes showed significant differential expression between normal and GBM brain tissues. We then focused on three genes with long and short APA isoforms that show inconsistent expression changes between normal and GBM brain tissues. These were myocyte enhancer factor 2D, heat shock factor binding protein 1, and polyhomeotic homolog 1 (Drosophila). Using the RNAelements program, we found that RBP binding sites were enriched in the alternative regions between the first and the last polyadenylation sites, which would result in the short APA forms escaping regulation from those RNA binding proteins. To the best of our knowledge, this report is the first comprehensive APA isoform dataset for GBM and normal brain tissues. Additionally, we demonstrated a putative novel APA-mediated mechanism for controlling RNA stability and translation for APA isoforms. These observations collectively lay a foundation for novel diagnostics and molecular mechanisms that can inform future therapeutic interventions for GBM.


Subject(s)
Brain Neoplasms/metabolism , Glioblastoma/metabolism , Neoplasm Proteins/metabolism , RNA Precursors/metabolism , RNA, Neoplasm/metabolism , RNA-Binding Proteins/metabolism , Base Sequence , Binding Sites/genetics , Brain/metabolism , Brain Neoplasms/genetics , Cell Line, Tumor , Databases, Nucleic Acid , Glioblastoma/genetics , Heat-Shock Proteins/genetics , Heat-Shock Proteins/metabolism , Humans , MADS Domain Proteins/genetics , MADS Domain Proteins/metabolism , MEF2 Transcription Factors , Myogenic Regulatory Factors/genetics , Myogenic Regulatory Factors/metabolism , Polyadenylation , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/metabolism , RNA Precursors/genetics , RNA Stability , RNA, Neoplasm/genetics , Software
13.
OMICS ; 16(12): 690-9, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23215807

ABSTRACT

Glioblastoma is the most common and aggressive primary brain tumor. MicroRNAs (miRNAs) are a set of noncoding RNA of about 20∼22 nt in length and they play regulatory roles such as regulating the expression of proteins. Altered miRNA expression is related to cancers, including glioblastoma. In this report, we used deep sequencing to explore the miRNA profiles of glioblastoma and normal brain tissues. We found 875 and 811 known miRNA and miRNA* in glioblastoma and normal brain tissue, respectively, representing the largest characterization of the miRNAs in GBM so far. 33 of them were upregulated in glioblastoma, including miR-21, which is well known as an oncomir, while 40 of them were downregulated. Using miR-10b, miR-124, miR-433, and miR-92b as examples, we verified the data by quantitative RT-PCR, suggesting that deep sequencing was able to capture the expression profiles of miRNAs. In addition, we found 18 novel miRNA and 16 new miRNA* in glioblastoma and normal brain tissues. This report provides a useful resource for future studies of the roles of miRNAs in the pathogenesis and early detection of glioblastoma.


Subject(s)
Brain/metabolism , Glioblastoma/genetics , High-Throughput Nucleotide Sequencing/methods , MicroRNAs/genetics , Humans , In Vitro Techniques
14.
PLoS One ; 7(8): e41335, 2012.
Article in English | MEDLINE | ID: mdl-22912670

ABSTRACT

SOX2 is an important stem cell marker and plays important roles in development and carcinogenesis. However, the role of SOX2 in Epithelial-Mesenchymal Transition has not been investigated. We demonstrated, for the first time, that SOX2 is involved in the Epithelial-Mesenchymal Transition (EMT) process as knock downof SOX2 in colorectal cancer (CRC) SW620 cells induced a Mesenchymal-Epithelial Transition (MET) process with recognized changes in the expression of key genes involved in the EMT process including E-cadherin and vimentin. In addition, we provided a link between SOX2 activity and the WNT pathway by showing that knock down of SOX2 reduced the WNT pathway activity in colorectal cancer (CRC) cells. We further demonstrated that SOX2 is involved in cell migration and invasion in vitro and in metastasis in vivo for CRC cells, and that the process might be mediated through the MMP2 activity. Finally, an IHC analysis of 44 cases of colorectal cancer patients suggested that SOX2 is a prognosis marker for metastasis of colorectal cancers.


Subject(s)
Colorectal Neoplasms/pathology , Epithelial-Mesenchymal Transition/genetics , Gene Expression Regulation, Neoplastic/genetics , Gene Silencing , Liver Neoplasms/secondary , SOXB1 Transcription Factors/deficiency , SOXB1 Transcription Factors/genetics , Animals , Cell Line, Tumor , Cell Movement/genetics , Colorectal Neoplasms/genetics , Down-Regulation/genetics , Female , Humans , Lymphatic Metastasis , Lymphoid Enhancer-Binding Factor 1/metabolism , Matrix Metalloproteinase 2/metabolism , Mice , Neoplasm Invasiveness , Signal Transduction/genetics , TCF Transcription Factors/metabolism , beta Catenin/metabolism
15.
OMICS ; 16(5): 263-7, 2012 May.
Article in English | MEDLINE | ID: mdl-22489821

ABSTRACT

NDRG4 is a member of the N-myc downregulated gene family (NDRG) belonging to the alpha/beta hydrolase superfamily. We have previously documented discrepancy between our analysis of the expression and function of NDRG4 in glioblastoma multiforme (GBM) and a recent publication by Schilling et al., who reported that NDRG4 is upregulated in GBM compared to human cortex tissues and knock down of NDRG4 reduced the viability of GBM cells. In the present study, we found that NDRG4 is indeed downregulated, at both RNA and protein levels, by quantitative RT-PCR and Western blot analysis, in GBM compared to normal tissues, and that over expression of NDRG4 inhibited proliferation of GBM cells. These new observations can inform the selection of lead molecular compounds for drug discovery as well as novel diagnostics for GBM. They also lend evidence to NDRG4 a role of tumor suppressor.


Subject(s)
Brain Neoplasms/genetics , Glioblastoma/genetics , Muscle Proteins/genetics , Nerve Tissue Proteins/genetics , Brain Neoplasms/metabolism , Brain Neoplasms/pathology , Cell Growth Processes/physiology , Cell Line, Tumor , Down-Regulation , Gene Expression Regulation, Neoplastic , Genes, Tumor Suppressor , Glioblastoma/metabolism , Glioblastoma/pathology , Humans , Muscle Proteins/biosynthesis , Nerve Tissue Proteins/biosynthesis
16.
Biomaterials ; 33(17): 4353-61, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22429982

ABSTRACT

A three-dimensional micro-scale perfusion-based two-chamber (3D-µPTC) tissue model system was developed to test the cytotoxicity of anticancer drugs in conjunction with liver metabolism. Liver cells with different cytochrome P450 (CYP) subtypes and glioblastoma multiforme (GBM) brain cancer cells were cultured in two separate chambers connected in tandem. Both chambers contained a 3D tissue engineering scaffold fabricated with biodegradable poly(lactic acid) (PLA) using a solvent-free approach. We used this model system to test the cytotoxicity of anticancer drugs, including temozolomide (TMZ) and ifosfamide (IFO). With the liver cells, TMZ showed a much lower toxicity to GBM cells under both 2D and 3D cell culture conditions. Comparing 2D, GBM cells cultured in 3D had much high viability under TMZ treatment. IFO was used to test the CYP-related metabolic effects. Cells with different expression levels of CYP3A4 differed dramatically in their ability to activate IFO, which led to strong metabolism-dependent cytotoxicity to GBM cells. These results demonstrate that our 3D-µPTC system could provide a more physiologically realistic in vitro environment than the current 2D monolayers for testing metabolism-dependent toxicity of anticancer drugs. It could therefore be used as an important platform for better prediction of drug dosing and schedule towards personalized medicine.


Subject(s)
Cell Culture Techniques/instrumentation , Cell Culture Techniques/methods , Diffusion Chambers, Culture , Perfusion/instrumentation , Perfusion/methods , Precision Medicine , Tissue Scaffolds , Cell Line, Tumor , Cell Survival/drug effects , Cytochrome P-450 CYP3A/metabolism , Dacarbazine/analogs & derivatives , Dacarbazine/chemistry , Dacarbazine/pharmacology , Glioblastoma/metabolism , Glioblastoma/pathology , Humans , Ifosfamide/chemistry , Ifosfamide/pharmacology , Ifosfamide/toxicity , Liver/drug effects , Liver/metabolism , Liver/pathology , Microscopy, Electron, Scanning , Polyesters/pharmacology , Porosity/drug effects , Temozolomide , Tissue Engineering
17.
Oncol Rep ; 27(3): 700-6, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22089331

ABSTRACT

MicroRNAs (miRNAs) are a novel group of short RNAs, about 20­22 nucleotide in length, that regulate gene expression in a post-transcriptional manner by affecting the stability or translation of mRNAs and play important roles in many biological processes. Many microRNAs have been implicated in glioblastoma. miR-31 is dysregulated in several types of cancer including colon, breast, prostate, gastric and lung cancers. However, the expression and role of miR-31 in glioblastoma are still unclear. In this study, we performed real-time reverse transcriptase polymerase chain reaction (RT-PCR) assays on 10 glioblastoma and 7 normal brain tissues. We found that miR-31 is down-regulated in glioblastoma compared with normal brain tissues. Ectopic expression of miR-31 inhibited migration and invasion ability of U251 glioma cells. Expression profiling analysis revealed that miR-31 affected the cell migration and motility process by regulating migration and invasion related genes. Finally, we demonstrated that miR-31 targeted radixin predominantly via inhibition of protein translation instead of degradation of mRNA.


Subject(s)
Brain Neoplasms/genetics , Cell Movement/genetics , Cytoskeletal Proteins/genetics , Glioblastoma/genetics , Membrane Proteins/genetics , MicroRNAs/genetics , Base Sequence , Brain Neoplasms/pathology , Cell Line, Tumor , Down-Regulation , Gene Expression Profiling/methods , Gene Expression Regulation, Neoplastic , Glioblastoma/pathology , Humans , MicroRNAs/biosynthesis , Neoplasm Invasiveness , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction
18.
Proteomics ; 11(5): 921-34, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21280222

ABSTRACT

SOX2 is a key gene implicated in maintaining the stemness of embryonic and adult stem cells that appears to re-activate in several human cancers including glioblastoma multiforme. Using immunoprecipitation (IP)/MS/MS, we identified 144 proteins that are putative SOX2 interacting proteins. Of note, SOX2 was found to interact with several heterogeneous nuclear ribonucleoprotein family proteins, including HNRNPA2B1, HNRNPA3, HNRNPC, HNRNPK, HNRNPL, HNRNPM, HNRNPR, HNRNPU, as well as other ribonucleoproteins, DNA repair proteins and helicases. Gene ontology (GO) analysis revealed that the SOX2 interactome was enriched for GO terms GO:0030529 ribonucleoprotein complex and GO:0004386 helicase activity. These findings indicate that SOX2 associates with the heterogeneous nuclear ribonucleoprotein complex, suggesting a possible role for SOX2 in post-transcriptional regulation in addition to its function as a transcription factor.


Subject(s)
Gene Expression Regulation , Glioblastoma/metabolism , Neoplasms, Nerve Tissue/metabolism , Protein Interaction Mapping , SOXB1 Transcription Factors/genetics , SOXB1 Transcription Factors/metabolism , Adult , Animals , Binding Sites , Cell Line, Tumor , DNA Helicases/metabolism , DNA Repair/physiology , Embryonic Stem Cells/physiology , Enhancer Elements, Genetic , Glioblastoma/genetics , Humans , Immunoprecipitation , Mass Spectrometry , Mice , Neoplasms, Nerve Tissue/genetics , Pluripotent Stem Cells/physiology , Protein Binding , RNA Processing, Post-Transcriptional , Rats , Ribonucleoproteins/metabolism
19.
Proc Natl Acad Sci U S A ; 108(4): 1591-6, 2011 Jan 25.
Article in English | MEDLINE | ID: mdl-21220328

ABSTRACT

Cancer cells are heterogeneous and, it has been proposed, fall into at least two classes: the tumor-initiating cancer stem cells (CSC) and the more differentiated tumor cells. The transmembrane protein CD133 has been widely used to isolate putative CSC populations in several cancer types, but its validity as a CSC marker and hence its clinical ramifications remain controversial. Here, we conducted transcriptomic profiling of sorted CD133(+) and CD133(-) cells from human glioblastoma multiforme (GBM) and, by subtractive analysis, established a CD133 gene expression signature composed of 214 differentially expressed genes. Extensive computational comparisons with a compendium of published gene expression profiles reveal that the CD133 gene signature transcriptionally resembles human ES cells and in vitro cultured GBM stem cells, and this signature successfully distinguishes GBM from lower-grade gliomas. More importantly, the CD133 gene signature identifies an aggressive subtype of GBM seen in younger patients with shorter survival who bear excessive genomic mutations as surveyed through the Cancer Genome Atlas Network GBM mutation spectrum. Furthermore, the CD133 gene signature distinguishes higher-grade breast and bladder cancers from their lower-grade counterparts. Our systematic analysis provides molecular and genetic support for the stem cell-like nature of CD133(+) cells and an objective means for evaluating cancer aggressiveness.


Subject(s)
Antigens, CD/metabolism , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Glioblastoma/genetics , Glycoproteins/metabolism , Peptides/metabolism , AC133 Antigen , Cluster Analysis , Embryonic Stem Cells/metabolism , Flow Cytometry , Glioblastoma/metabolism , Glioblastoma/pathology , Humans , Immunohistochemistry , Neoplastic Stem Cells/metabolism , Neural Stem Cells/metabolism , Oligonucleotide Array Sequence Analysis , Tumor Cells, Cultured
20.
BMC Genomics ; 12: 11, 2011 Jan 06.
Article in English | MEDLINE | ID: mdl-21211035

ABSTRACT

BACKGROUND: SOX2 is a key gene implicated in maintaining the stemness of embryonic and adult stem cells. SOX2 appears to re-activate in several human cancers including glioblastoma multiforme (GBM), however, the detailed response program of SOX2 in GBM has not yet been defined. RESULTS: We show that knockdown of the SOX2 gene in LN229 GBM cells reduces cell proliferation and colony formation. We then comprehensively characterize the SOX2 response program by an integrated analysis using several advanced genomic technologies including ChIP-seq, microarray profiling, and microRNA sequencing. Using ChIP-seq technology, we identified 4883 SOX2 binding regions in the GBM cancer genome. SOX2 binding regions contain the consensus sequence wwTGnwTw that occurred 3931 instances in 2312 SOX2 binding regions. Microarray analysis identified 489 genes whose expression altered in response to SOX2 knockdown. Interesting findings include that SOX2 regulates the expression of SOX family proteins SOX1 and SOX18, and that SOX2 down regulates BEX1 (brain expressed X-linked 1) and BEX2 (brain expressed X-linked 2), two genes with tumor suppressor activity in GBM. Using next generation sequencing, we identified 105 precursor microRNAs (corresponding to 95 mature miRNAs) regulated by SOX2, including down regulation of miR-143, -145, -253-5p and miR-452. We also show that miR-145 and SOX2 form a double negative feedback loop in GBM cells, potentially creating a bistable system in GBM cells. CONCLUSIONS: We present an integrated dataset of ChIP-seq, expression microarrays and microRNA sequencing representing the SOX2 response program in LN229 GBM cells. The insights gained from our integrated analysis further our understanding of the potential actions of SOX2 in carcinogenesis and serves as a useful resource for the research community.


Subject(s)
Glioblastoma/genetics , MicroRNAs/genetics , SOXB1 Transcription Factors/metabolism , Chromatin Immunoprecipitation , Humans , MicroRNAs/metabolism , Oligonucleotide Array Sequence Analysis , Sequence Analysis, DNA
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