Differential Molecular Function of RTKs in GBM Biology is Modulated by Sexual Dimorphism

Description

Glioblastoma (GBM) is the most common and aggressive form of primary brain tumor in adults and is diagnosed more often in males and in females. The current standard of care includes surgical resection, chemotherapy, and radiation therapy, though the tumor

Glioblastoma (GBM) is the most common and aggressive form of primary brain tumor in adults and is diagnosed more often in males and in females. The current standard of care includes surgical resection, chemotherapy, and radiation therapy, though the tumor often recurs and overall survival for this disease remains low, necessitating the investigation of potential new nodes of treatment. In the search for individualized therapies for GBM, receptor tyrosine kinases (RTKs) have been discovered to mediate different responses and outcomes between male and female patients. This thesis aims to investigate the differential role two RTKs, EGFR and PDGFR, in mediating proliferation, migration, and invasion of GBM cells between males and females. Cell proliferation, migration, and invasion assays were performed using isogenic matched male and female murine GBM cell lines with specific RTK expression mimicking in vivo alterations to their respective oncogenes. Statistical analysis to compare the means of these markers was used to determine discrete trends in male and female cell lines, as well as between males and females with the same mutations. In vitro proliferation, migration, and invasion assays revealed distinct patterns of sex mediated molecular RTK function between males and females. EGFR and PDGFR expression were shown to play different roles in progression between these three metrics. Additionally, the used of an isogenic murine model with sex as a controlled variable allowed male-to-female comparisons, yielding data suggesting some RTKs may attenuate progression in one or more of these benchmarks in one sex more than the other. This study highlights the need for further investigation into the role RTKs play in male versus female GBM progression, which could potentially lead to the creation of new targeted treatments and personalized medicine approaches.

Date Created
2023-05
Agent

SRC Dependent EGFRvIII-STAT5 Activation Drives Resistance of Glioblastoma Cells

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Description

Glioblastoma (GBM) is the most lethal primary brain tumor in adults with a less than 5% chance of survival beyond 5 years. With few effective therapies beyond the standard of care, there are often treatment resistant recurrences seen in most

Glioblastoma (GBM) is the most lethal primary brain tumor in adults with a less than 5% chance of survival beyond 5 years. With few effective therapies beyond the standard of care, there are often treatment resistant recurrences seen in most patients. STAT5 is a protein that has shown to be upregulated in highly invasive and treatment resistant GBM. Elucidating the role of STAT5 in GBM could reveal a node of therapeutic vulnerability in primary and recurrent GBM.

Date Created
2022-05
Agent

The Development of Small Molecule Inhibitors of the TWEAK-Fn14 Pathway in Glioblastoma Multiforme

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Description
Glioblastoma multiforme is the most common and aggressive primary malignant brain tumor in adults, exhibiting a median survival of only 15 months after diagnosis. A significant challenge in treating GBM is the ability of glioma cells to invade normal brain

Glioblastoma multiforme is the most common and aggressive primary malignant brain tumor in adults, exhibiting a median survival of only 15 months after diagnosis. A significant challenge in treating GBM is the ability of glioma cells to invade normal brain tissue, escape surgical resection, and resist radiotherapy and chemotherapy. We have previously demonstrated that the TWEAK-Fn14 signaling axis plays an important role in glioma cell invasion and discovered a small molecule, L524-0366, that specifically disrupts the TWEAK-Fn14 interaction. However, low affinity limits L524-0366’s clinical feasibility. By utilizing structure-activity relationship analyses of L524-0366, we identified additional small molecules that may inhibit TWEAK-Fn14 signaling. Here, we identify five additional novel Fn14 signaling inhibitors that specifically inhibited TWEAK-Fn14 NF-κB-dependent signaling and suppressed TWEAK-induced glioma cell migration. Furthermore, we demonstrate that two molecules exhibit improved affinity for Fn14, two molecules showed binding to the TWEAK ligand but not Fn14, and one showed no binding to either TWEAK or Fn14. These molecules will be further tested for in vitro and in vivo functionality, and serve as foundations for additional medicinal chemistry for drug modifications.
Date Created
2016-12
Agent

TWEAK functions as chemotactic factor for glioma cells via Lyn activation

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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 to chemotherapeutic- and radiation-induced apoptosis. We have previously shown that

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.
Date Created
2013-05
Agent

Multi-Parametric MRI and Texture Analysis to Visualize Spatial Histologic Heterogeneity and Tumor Extent in Glioblastoma

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Description

Background: Genetic profiling represents the future of neuro-oncology but suffers from inadequate biopsies in heterogeneous tumors like Glioblastoma (GBM). Contrast-enhanced MRI (CE-MRI) targets enhancing core (ENH) but yields adequate tumor in only ~60% of cases. Further, CE-MRI poorly localizes infiltrative tumor

Background: Genetic profiling represents the future of neuro-oncology but suffers from inadequate biopsies in heterogeneous tumors like Glioblastoma (GBM). Contrast-enhanced MRI (CE-MRI) targets enhancing core (ENH) but yields adequate tumor in only ~60% of cases. Further, CE-MRI poorly localizes infiltrative tumor within surrounding non-enhancing parenchyma, or brain-around-tumor (BAT), despite the importance of characterizing this tumor segment, which universally recurs. In this study, we use multiple texture analysis and machine learning (ML) algorithms to analyze multi-parametric MRI, and produce new images indicating tumor-rich targets in GBM.

Methods: We recruited primary GBM patients undergoing image-guided biopsies and acquired pre-operative MRI: CE-MRI, Dynamic-Susceptibility-weighted-Contrast-enhanced-MRI, and Diffusion Tensor Imaging. Following image coregistration and region of interest placement at biopsy locations, we compared MRI metrics and regional texture with histologic diagnoses of high- vs low-tumor content (≥80% vs <80% tumor nuclei) for corresponding samples. In a training set, we used three texture analysis algorithms and three ML methods to identify MRI-texture features that optimized model accuracy to distinguish tumor content. We confirmed model accuracy in a separate validation set.

Results: We collected 82 biopsies from 18 GBMs throughout ENH and BAT. The MRI-based model achieved 85% cross-validated accuracy to diagnose high- vs low-tumor in the training set (60 biopsies, 11 patients). The model achieved 81.8% accuracy in the validation set (22 biopsies, 7 patients).

Conclusion: Multi-parametric MRI and texture analysis can help characterize and visualize GBM’s spatial histologic heterogeneity to identify regional tumor-rich biopsy targets.

Date Created
2015-11-24
Agent

The dissection of signaling cascades in neural stem cell proliferation & GBM promotion

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Description
Cells live in complex environments and must be able to adapt to environmental changes in order to survive. The ability of a cell to survive and thrive in a changing environment depends largely on its ability to receive and respond

Cells live in complex environments and must be able to adapt to environmental changes in order to survive. The ability of a cell to survive and thrive in a changing environment depends largely on its ability to receive and respond to extracellular signals. Initiating with receptors, signal transduction cascades begin translating extracellular signals into intracellular messages. Such signaling cascades are responsible for the regulation of cellular metabolism, cell growth, cell movement, transcription, translation, proliferation and differentiation. This dissertation seeks to dissect and examine critical signaling pathways involved in the regulation of proliferation in neural stem cells (Chapter 2) and the regulation of Glioblastoma Multiforme pathogenesis (GBM; Chapter 3). In Chapter 2 of this dissertation, we hypothesize that the mTOR signaling pathway plays a significant role in the determination of neural stem cell proliferation given its control of cell growth, metabolism and survival. We describe the effect of inhibition of mTOR signaling on neural stem cell proliferation using animal models of aging. Our results show that the molecular method of targeted inhibition may result in differential effects on neural stem cell proliferation as the use of rapamycin significantly reduced proliferation while the use of metformin did not. Abnormal signaling cascades resulting in unrestricted proliferation may lead to the development of brain cancer, such as GBM. In Chapter 3 of this dissertation, we hypothesize that the inhibition of the protein kinase, aPKCλ results in halted GBM progression (invasion and proliferation) due to its central location in multiple signaling cascades. Using in-vitro and in-vivo models, we show that aPKCλ functions as a critical node in GBM signaling as both cell-autonomous and non-cell-autonomous signaling converge on aPKCλ resulting in pathogenic downstream effects. This dissertation aims to uncover the molecular mechanisms involved in cell signaling pathways which are responsible for critical cellular effects such as proliferation, invasion and transcriptional regulation.
Date Created
2014
Agent