Matching Items (17)

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Disarming Olig2: Targeting its partner protein Hdac1

Description

Glioblastoma is the most aggressive and lethal brain tumor, due to its resistance to current conventional therapy. The resistance to chemo- and radiotherapy has been attributed to a special population

Glioblastoma is the most aggressive and lethal brain tumor, due to its resistance to current conventional therapy. The resistance to chemo- and radiotherapy has been attributed to a special population of cells known as glioma stem cells. Previous literature has shown the importance of a Central Nervous System-restricted transcription factor OLIG2 in maintaining the tumor-propagating potential of these glioma stem cells. OLIG2's function was further elucidated, with its pro-mitogenic function due to its ability to negatively regulate the p53 pathway by suppressing the acetylation of the p53 protein's C terminal domain. Past work in our lab has confirmed that one of OLIG2's partner proteins is Histone Deacetylase 1 (HDAC1). In vitro experiments have also shown that targeting HDAC1 using hairpin RNA in glioma stem cells negatively impacts proliferation. In a survival study using a murine glioma model, targeting Hdac1 using hairpin RNA is shown to reduce tumor burden and increase survival. In this paper, we demonstrate that silencing Hdac1 expression reduces proliferation, increases cell death, likely a result of increased acetylation of p53. Olig2 expression levels seem to be unaffected in GSCs, demonstrating that the Hdac1 protein ablation is indeed lethal to GSCs. This work builds upon previously collected results, confirming that Hdac1 is a potential surrogate target for Olig2's pro-mitotic function in regulating the p53 pathway.

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Date Created
  • 2017-05

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The Effects of Human Hairless Gene Overexpression on U87 MG Glioblastoma Cell Function

Description

Glioblastoma multiforme (GBM) is an aggressive malignant brain tumor with a median prognosis of 14 months. Human hairless protein (HR) is a 130 kDa nuclear transcription factor that plays a

Glioblastoma multiforme (GBM) is an aggressive malignant brain tumor with a median prognosis of 14 months. Human hairless protein (HR) is a 130 kDa nuclear transcription factor that plays a critical role in skin and hair function but was found to be highly expressed in neural tissue as well. The expression of HR in GBM tumor cells is significantly decreased compared to the normal brain tissue and low levels of HR expression is associated with shortened patient survival. We have recently reported that HR is a DNA binding phosphoprotein, which binds to p53 protein and p53 responsive element (p53RE) in vitro and in intact cells. We hypothesized that HR can regulate p53 downstream target genes, and consequently affects cellular function and activity. To test the hypothesis, we overexpressed HR in normal human embryonic kidney HEK293 and GBM U87MG cell lines and characterized these cells by analyzing p53 target gene expression, viability, cell-cycle arrest, and apoptosis. The results revealed that the overexpressed HR not only regulates p53-mediated target gene expression, but also significantly inhibit cell viability, induced early apoptosis, and G2/M cell cycle arrest in U87MG cells, compared to mock groups. Translating the knowledge gained from this research on the connections between HR and GBM could aid in identifying novel therapies to circumvent GBM progression or improve clinical outcome.

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Date Created
  • 2018-05

Imaging Local Drug Delivery

Description

Imaging analysis of local drug delivery is important because in both studies involving chemotherapy targeted toward glioblastoma and antimicrobial addressing infection, the drug concentration and distribution are unknown. There are

Imaging analysis of local drug delivery is important because in both studies involving chemotherapy targeted toward glioblastoma and antimicrobial addressing infection, the drug concentration and distribution are unknown. There are a variety of studies focused on the local delivery of drug to a targeted location, but we are presenting a way of quantifying the concentration of the drug and the distribution of the drug during a period of time. This study aims to do that by utilizing Materialise Mimics to analyze the MRI images of local drug delivery in glioblastoma in canines and antimicrobial gel in rabbit femurs. The focus of the technique is to register the anatomy in T1-weighted spin echo images to the drug delivery in T2 flow attenuated inversion recovery (FLAIR) images in order to see where the drug went and did not go relative to the anatomical part. Both studies focus on addressing effective volumes of drug to a designated anatomical area, in which the delivery can be difficult as it involves bypassing the blood brain barrier in the first study and achieving effective volumes while preventing toxicity to the kidneys in the second study. The goal of this project lies in determining the drug volumes and location for the specified duration and anatomical part.

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Created

Date Created
  • 2018-05

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Evaluating STAT5 Signature in Recurrent Glioblastoma

Description

Background: Recurrent glioblastoma (GBM) is resistant to available treatments and continued growth of the tumor is inevitable; this process is facilitated by the expression of genes regulated by the Signal

Background: Recurrent glioblastoma (GBM) is resistant to available treatments and continued growth of the tumor is inevitable; this process is facilitated by the expression of genes regulated by the Signal Transducer and Activator of Transcription (STAT) family of transcription factors, namely STAT5, active in the invasive rim of GBM tumors. Currently, there are no targeted therapies for recurrent GBM that increase the overall patient survival rate. This study aims to analyze the differential expression of genes regulated by STAT5 between primary and recurrent GBM.<br/>Methods: Analysis of whole exome and RNA sequencing were performed on matched bulk primary and multiple recurrent tumor samples from GBM patients who received the current standard care to determine significant changes in gene expression of STAT3/5 targets. <br/>Results: Statistical analysis reveals a decrease in Synaptotagmin 2 (SYT2) and Pleckstrin Homology Domain Containing A3 (PLEKHA3) at recurrence, previously identified as potential STAT5 targets. <br/>Conclusions: To get a better understanding of the roles of STAT5 in GBM recurrence, their downstream effects need to be better understood. The transcriptomic program initiated by STAT5 activation is distinct from that of STAT3 activation. The roles of STAT5 target genes in GBM are poorly characterized, so further research should focus on understanding the effects of altered expression of these genes as they relate to STAT3/5 in GBM recurrence.

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Date Created
  • 2021-05

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Investigating the role of SGEF (ARHGEF26) in cell survival through its interactions with BRCA1 in TMZ-resistant Glioblastoma

Description

Glioblastoma (GB) is one of the deadliest cancers and the most common form of adult primary brain tumors. SGEF (ARHGEF26) has been previously shown to be overexpressed in GB tumors,

Glioblastoma (GB) is one of the deadliest cancers and the most common form of adult primary brain tumors. SGEF (ARHGEF26) has been previously shown to be overexpressed in GB tumors, play a role in cell invasion/migration, and increase temozolomide (TMZ) resistance.[3] It was hypothesized parental LN229 cell lines with SGEF knockdown (LN229-SGEFi) will show decreased metabolism in the MTS assay and decreased colony formation in a colony formation assay compared to parental LN229 cells after challenging the two cell lines with TMZ. For WB and co-immunoprecipitation (co-IP), parental LN229 cells with endogenous SGEF and BRCA were expected to interact and stain in the BRCA1:IP WB. LN229-SGEFi cells were expected to show very little SGEF precipitated due to shRNA targeted knockdown of SGEF. In conditions with mutations in the BRCA1 binding site (LN229-SGEFi + AdBRCAm/AdDM), SGEF expression was expected to decrease compared to parental LN229 or LN229-SGEFi cells reconstituted with WT SGEF (LN229-SGEFi + AdWT). LN229 infected with AdSGEF with a mutated nuclear localization signal (LN229-SGEFi + AdNLS12m) were expected to show BRCA and SGEF interaction since whole cell lysates were used for the co-IP. MTS data showed no significant differences in metabolism between the two cell lines at all three time points (3, 5, and 7 days). Western blot analysis was successful at imaging both SGEF and BRCA1 protein bands from whole cell lysate. The CFA showed no significant difference between cell lines after being challenged with 500uM TMZ. The co-IP immunoblot showed staining for BRCA1 and SGEF for all lysate samples, including unexpected lysates such as LN229-SGEFi, LN229-SGEFi + AdBRCAm, and LN229-SGEFi + AdDM. These results suggested either an indirect protein interaction between BRCA1 and SGEF, an additional BRCA binding site not included in the consensus, or possible detection of the translocated SGEF in knockdown cells lines since shRNA cannot enter the nucleus. Further optimization of CO-IP protocol, MTS assay, and CFA will be needed to characterize the SGEF/BRCA1 interaction and its role in cell survival.

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Created

Date Created
  • 2021-05

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Development of a Blood Brain Barrier Permeability Database for Investigational Anti-Cancer Agents for Use in Glioblastoma Research

Description

Glioblastoma (GBM) is an extremely malignant form of brain cancer characterized by rapid progression and poor patient survival. Even after standard of care treatments, less than ten percent of patients

Glioblastoma (GBM) is an extremely malignant form of brain cancer characterized by rapid progression and poor patient survival. Even after standard of care treatments, less than ten percent of patients with this disease survive five years. More effective therapeutic options are urgently needed to improve outcomes for patients with GBM. Adequate drug delivery is a critical challenge in GBM treatment, as drugs delivered systemically must be able to penetrate the blood brain barrier (BBB) and reach the tumor at therapeutic levels. To address this, we developed a resource to catalog BBB penetration information for investigational agents currently in clinical trials in cancer. Using an in silico prediction model and manual annotation to capture existing knowledge from the published literature, BBB content for ~500 investigational drugs was added to the investigational database tool. In addition to BBB content, the database also includes information on the gene targets of the included therapies. The investigational database tool was used to identify investigational agents that (1) may have increased activity against GBM based on the presence of a specific mutation in the tumor sample and (2) have evidence suggesting the compounds may penetrate the BBB. By prioritizing investigational agents for further study based on evidence for BBB penetration, this resource can help the GBM research community pursue more effective treatments for GBM.

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Created

Date Created
  • 2016-05

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Impact of Sex Differences and Tumor Location on Survival Outcomes in Glioblastoma Patients Receiving Standard of Care

Description

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults and is linked to poor survival in affected patients due to its invasive and aggressive nature. The potential

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults and is linked to poor survival in affected patients due to its invasive and aggressive nature. The potential role of sexual dimorphism in GBM outcomes has long been overlooked. Notably, males and females differ in tumor behavior across many cancers1, which may be attributable to differences in genetic makeup and physiology, and in GBM there is a difference in incidence rate between males and females. The aim of the study was to investigate sex differences in GBM patients and compare median survival outcomes (OS) and progression-free survival outcomes (PFS) between sexes based on tumor location, laterality, age, tumor volume, and extent of resection. Patients who received standard-of-care (Stupp protocol) consisting of surgical intervention, concomitant chemoradiation, and 6 cycles of adjuvant temozolomide (TMZ) were included in this study to investigate sex differences in tumor characteristics (n = 216; males: n = 129, females: n = 87). Pre-surgical MRIs, specifically T1Gd sequences, were analyzed to determine tumor laterality and location. The patient cohort was divided into two groups indicating the extent of resection (EOR) they received: Gross Total Resection (GTR) and Subtotal Resection (STR). Additionally, the patient cohort was split into three age groups (Group I: 18-29, Group II: 30-49, and Group III: >50). Analyses were done using independent t-test and Cox proportional hazard modeling to determine which variables affect patient survival. The log-rank test was utilized to compare differences in survival rate in Kaplan-Meier analysis.
Overall, our results suggest that female patients receiving standard-of-care may have a better prognosis than male patients. There was a significant difference in OS and PFS in females showing an increase in survival. Additionally, survival was significantly different between sexes following resection, with female patients receiving STR or GTR having longer OS and PFS than males. The difference in median OS between sexes is more pronounced among younger patients. Among five different brain locations, female patients who possess a frontal lobe tumor may live longer than male patients. The apparent difference in OS for patients living >1000 days in the Kaplan-Meier plot warrants further investigation in a larger cohort. Following tumor resection, female patients with a frontal lobe tumor may survive longer in comparison to male patients. Comparing brain hemispheres, patients who possessed a tumor on the left may survive longer. Investigating tumor location and tumor laterality, our results suggests that female patients with a left frontal lobe tumor show a significant survival advantage in comparison to females who possess a right frontal lobe tumor.

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Created

Date Created
  • 2018-05

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Microglia Motility in the Context of a PDGF Induced Glioblastoma

Description

Tumor associated microglia-and-macrophages (TAMS) may constitute up to 30% of the composition of glioblastoma. Through mechanisms not well understood, TAMS are thought to aid the progression and invasiveness of glioblastoma.

Tumor associated microglia-and-macrophages (TAMS) may constitute up to 30% of the composition of glioblastoma. Through mechanisms not well understood, TAMS are thought to aid the progression and invasiveness of glioblastoma. In an effort to investigate properties of TAMS in the context of glioblastoma, I utilized data from a PDGF-driven rat model of glioma that highly resembles human glioblastoma. Data was collected from time-lapse microscopy of slice cultures that differentially labels glioma cells and also microglia cells within and outside the tumor microenvironment. Here I show that microglia localize in the tumor and move with greater speed and migration than microglia outside the tumor environment. Following previous studies that show microglia can be characterized by certain movement distributions based on environmental influences, in this study, the majority of microglia movement was characterized by a power law distribution with a characteristic power law exponent lower than outside the tumor region. This indicates that microglia travel at greater distances within the tumor region than outside of it.

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Created

Date Created
  • 2013-12

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Glioblastoma in the Crosshairs: Development of a Dual Reporter Assay for Discovery of Olig2 Inhibiting Drugs

Description

A coincidence reporter construct, consisting of the p21-promoter and two luciferase genes (Firefly and Renilla), was constructed for the screening of drugs that might inhibit Olig2's tumorigenic role in glioblastoma.

A coincidence reporter construct, consisting of the p21-promoter and two luciferase genes (Firefly and Renilla), was constructed for the screening of drugs that might inhibit Olig2's tumorigenic role in glioblastoma. The reporter construct was tested using an Olig2 inhibitor, HSP990, as well as short hairpin RNA targeting Olig2. Further confirmatory analysis is needed before the reporter cell line is ready for high-throughput screening at the NIH and lead compound selection.

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Created

Date Created
  • 2014-05

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TWEAK functions as chemotactic factor for glioma cells via Lyn activation

Description

The long-term survival of patients with glioblastoma multiforme is compromised by the tumor's proclivity for local invasion into the surrounding normal brain. These invasive cells escape surgery and display resistance

The long-term survival of patients with glioblastoma multiforme is compromised by the tumor's proclivity for local invasion into the surrounding normal brain. These invasive cells escape surgery and display resistance to chemotherapeutic- and radiation-induced apoptosis. We have previously shown that tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor superfamily, can stimulate glioma cell invasion and survival via binding to the fibroblast growth factor-inducible 14 (Fn14) receptor and subsequent activation of the Rac1/NF-kappaB pathway. In addition, we have reported previously that Fn14 is expressed at high levels in migrating glioma cells in vitro and invading glioma cells in vivo. Here we demonstrate that TWEAK can act as a chemotactic factor for glioma cells, a potential process to drive cell invasion into the surrounding brain tissue. Specifically, we detected a chemotactic migration of glioma cells to the concentration gradient of TWEAK. Since Src family kinases (SFK) have been implicated in chemotaxis, we next determined whether TWEAK:Fn14 engagement activated these cytoplasmic tyrosine kinases. Our data shows that TWEAK stimulation of glioma cells results in a rapid phosphorylation of the SFK member Lyn as determined by multiplex Luminex assay and verified by immunoprecipitation. Immunodepletion of Lyn by siRNA oligonucleotides suppressed the chemoattractive effect of TWEAK on glioma cells. We hypothesize that TWEAK secretion by cells present in the glioma microenvironment induce invasion of glioma cells into the brain parenchyma. Understanding the function and signaling of the TWEAK-Fn14 ligand-receptor system may lead to development of novel therapies to therapeutically target invasive glioma cells.

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Agent

Created

Date Created
  • 2013-05