Preclinical and Clinical-Scale Magnetic Particle Imaging of Natural Killer Cells: in vitro and ex vivo Demonstration of Cellular Sensitivity, Resolution, and Quantification.

Purpose: Clinical adoption of NK cell immunotherapy is underway for medulloblastoma and osteosarcoma, however there is currently little feedback on cell fate after administration. We propose magnetic particle imaging (MPI) may have applications for the quantitative detection of NK cells.

Procedures: Human-derived NK-92 cells were labeled by co-incubation with iron oxide nanoparticles (VivoTrax™) for 24 h then excess nanoparticles were washed with centrifugation.

Pulsed focused ultrasound alters the proteomic profile of the tumor microenvironment in a syngeneic mouse model of glioblastoma.

Purpose: Glioblastoma (GBM), a lethal primary adult malignancy, is difficult to treat because of the restrictive nature of the blood-brain barrier (BBB), blood-tumor barrier (BTB), and the immunosuppressive tumor microenvironment (TME). Since pulsed focused ultrasound (pFUS) is currently used to improve therapeutic deliveries across these barriers, this study aims to characterize the impact of pFUS on the TME proteomics upon opening the BBB and BTB.

Methods: We utilized MRI-guided, pFUS with ultrasound contrast microbubbles (termed 'pFUS' herein) to selectively and transiently open the BBB and BTB investigating proteomic modifications in the TME.

MGMT function determines the differential response of ATR inhibitors with DNA-damaging agents in glioma stem cells for GBM therapy.

Background: The most prevalent cancer treatments cause cell death through DNA damage. However, DNA damage response (DDR) repair pathways, initiated by tumor cells, can withstand the effects of anticancer drugs, providing justification for combining DDR inhibitors with DNA-damaging anticancer treatments.

Methods: Cell viability assays were performed with CellTiter-Glo assay.

Neuronal differentiation drives the antitumor activity of mitogen-activated protein kinase kinase (MEK) inhibition in glioblastoma.

Background: Epidermal growth factor receptor (EGFR) amplification is found in nearly 40%-50% of glioblastoma cases. Several EGFR inhibitors have been tested in glioblastoma but have failed to demonstrate long-term therapeutic benefit, presumably because of acquired resistance. Targeting EGFR downstream signaling with mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) inhibitors would be a more effective approach to glioblastoma treatment.

EGFR suppresses p53 function by promoting p53 binding to DNA-PKcs: a noncanonical regulatory axis between EGFR and wild-type p53 in glioblastoma.

Background: Epidermal growth factor receptor (EGFR) amplification and TP53 mutation are the two most common genetic alterations in glioblastoma multiforme (GBM). A comprehensive analysis of the TCGA GBM database revealed a subgroup with near mutual exclusivity of EGFR amplification and TP53 mutations indicative of a role of EGFR in regulating wild-type-p53 (wt-p53) function. The relationship between EGFR amplification and wt-p53 function remains undefined and this study describes the biological significance of this interaction in GBM.

The promise of DNA damage response inhibitors for the treatment of glioblastoma.

Glioblastoma (GBM), the most aggressive primary brain tumor, has a dismal prognosis. Despite our growing knowledge of genomic and epigenomic alterations in GBM, standard therapies and outcomes have not changed significantly in the past two decades. There is therefore an urgent unmet need to develop novel therapies for GBM.

PARP-mediated PARylation of MGMT is critical to promote repair of temozolomide-induced O6-methylguanine DNA damage in glioblastoma.

Background: Temozolomide (TMZ) resistance in glioblastoma multiforme (GBM) is mediated by the DNA repair protein O6-methylguanine DNA methyltransferase (MGMT). MGMT promoter methylation (occurs in about 40% of patients) is associated with loss of MGMT expression (MGMT-) that compromises DNA repair, leading to a favorable response to TMZ therapy. The 60% of patients with unmethylated MGMT (MGMT+) GBM experience resistance to TMZ; in these patients, understanding the mechanism of MGMT-mediated repair and modulating MGMT activity may lead to enhanced TMZ activity.

Integrated analysis of telomerase enzymatic activity unravels an association with cancer stemness and proliferation.

Active telomerase is essential for stem cells and most cancers to maintain telomeres. The enzymatic activity of telomerase is related but not equivalent to the expression of TERT, the catalytic subunit of the complex. Here we show that telomerase enzymatic activity can be robustly estimated from the expression of a 13-gene signature.

Amplification Induces Increased DNA Damage Response and Renders Selective Sensitivity to Talazoparib (PARP Inhibitor) in Glioblastoma.

Purpose: Exploration of novel strategies to extend the benefit of PARP inhibitors beyond -mutant cancers is of great interest in personalized medicine. Here, we identified amplification as a potential biomarker to predict sensitivity to PARP inhibition, providing selection for the glioblastoma (GBM) patient population who will benefit from PARP inhibition therapy.

Experimental Design: Selective sensitivity to the PARP inhibitor talazoparib was screened and validated in two sets [test set ( = 14) and validation set ( = 13)] of well-characterized patient-derived glioma sphere-forming cells (GSC).

BRCA1 identified as a modulator of temozolomide resistance in P53 wild-type GBM using a high-throughput shRNA-based synthetic lethality screening.

Glioblastoma multiforme (GBM), the most common type of primary brain tumor, is universally fatal, with a median survival duration ranging from 12-15 months despite maximum treatment efforts. Temozolomide (TMZ) is the current standard of care for GBM patients; however patients usually develop resistance to TMZ and limits its benefit. The identification of novel synergistic targets in GBM will lead to the development of new targeted drugs, which could be combined with broad-spectrum cytotoxic agents.

Wild-type defined gamma-secretase inhibitor sensitivity and synergistic activity with doxorubicin in GSCs.

Glioblastoma (GBM) is the most common and lethal primary intracranial tumor. Aggressive surgical resection plus radiotherapy and temozolomide have prolonged patients' median survival to only 14.6 months.

Tie2-FGFR1 Interaction Induces Adaptive PI3K Inhibitor Resistance by Upregulating Aurora A/PLK1/CDK1 Signaling in Glioblastoma.

PI3K-targeting therapy represents one of the most sought-after therapies for glioblastoma (GBM). Several small-molecule inhibitors have been evaluated in clinical trials, however, the emergence of resistance limits treatment potential. Here, we generated a patient-derived glioma sphere-forming cell (GSC) xenograft model resistant to the PI3K-specific inhibitor BKM-120.

Buparlisib in Patients With Recurrent Glioblastoma Harboring Phosphatidylinositol 3-Kinase Pathway Activation: An Open-Label, Multicenter, Multi-Arm, Phase II Trial.

Purpose: Phosphatidylinositol 3-kinase (PI3K) signaling is highly active in glioblastomas. We assessed pharmacokinetics, pharmacodynamics, and efficacy of the pan-PI3K inhibitor buparlisib in patients with recurrent glioblastoma with PI3K pathway activation.

Methods: This study was a multicenter, open-label, multi-arm, phase II trial in patients with PI3K pathway-activated glioblastoma at first or second recurrence.

PAF promotes stemness and radioresistance of glioma stem cells.

An integrated genomic and functional analysis to elucidate DNA damage signaling factors promoting self-renewal of glioma stem cells (GSCs) identified proliferating cell nuclear antigen (PCNA)-associated factor () up-regulation in glioblastoma. PAF is preferentially overexpressed in GSCs. Its depletion impairs maintenance of self-renewal without promoting differentiation and reduces tumor-initiating cell frequency.

Activation of WEE1 confers resistance to PI3K inhibition in glioblastoma.

Background: Oncogenic activation of phosphatidylinositol-3 kinase (PI3K) signaling plays a pivotal role in the development of glioblastoma (GBM). However, pharmacological inhibition of PI3K has so far not been therapeutically successful due to adaptive resistance through a rapid rewiring of cancer cell signaling. Here we identified that WEE1 is activated after transient exposure to PI3K inhibition and confers resistance to PI3K inhibition in GBM.

APOBEC3G acts as a therapeutic target in mesenchymal gliomas by sensitizing cells to radiation-induced cell death.

Genomic, transcriptional, and proteomic analyses of brain tumors reveal that subtypes differ in their pathway activity, progression, and response to therapy. We performed an expression profiling of Glioma Initiating Cells (GICs) and comparative analysis between different groups of GICs indicates major variations in gene expression. Hierarchical clustering analysis revealed groups of GICs reflecting their heterogeneity, and among some of the genes as major regulators of mesenchymal phenotype, we identified ABOBEC3G as one of the most discriminating genes in mesenchymal group.

Preclinical therapeutic efficacy of a novel blood-brain barrier-penetrant dual PI3K/mTOR inhibitor with preferential response in PI3K/PTEN mutant glioma.

Glioblastoma (GBM) is an ideal candidate disease for signal transduction targeted therapy because the majority of these tumors harbor genetic alterations that result in aberrant activation of growth factor signaling pathways. Loss of heterozygosity of chromosome 10, mutations in the tumor suppressor gene PTEN, and PI3K mutations are molecular hallmarks of GBM and indicate poor prognostic outcomes in many cancers. Consequently, inhibiting the PI3K pathway may provide therapeutic benefit in these cancers.

MSK1-Mediated β-Catenin Phosphorylation Confers Resistance to PI3K/mTOR Inhibitors in Glioblastoma.

Glioblastoma (GBM) represents a compelling disease for kinase inhibitor therapy because most of these tumors harbor genetic alterations that result in aberrant activation of growth factor-signaling pathways. The PI3K/mammalian target of the rapamycin (mTOR) pathway is dysregulated in over 50% of human GBM but remains a challenging clinical target. Inhibitors against PI3K/mTOR mediators have limited clinical efficacy as single agents.

A high Notch pathway activation predicts response to γ secretase inhibitors in proneural subtype of glioma tumor-initiating cells.

Genomic, transcriptional, and proteomic analyses of brain tumors reveal subtypes that differ in pathway activity, progression, and response to therapy. However, a number of small molecule inhibitors under development vary in strength of subset and pathway-specificity, with molecularly targeted experimental agents tending toward stronger specificity. The Notch signaling pathway is an evolutionarily conserved pathway that plays an important role in multiple cellular and developmental processes.

A survey of intragenic breakpoints in glioblastoma identifies a distinct subset associated with poor survival.

With the advent of high-throughput sequencing technologies, much progress has been made in the identification of somatic structural rearrangements in cancer genomes. However, characterization of the complex alterations and their associated mechanisms remains inadequate. Here, we report a comprehensive analysis of whole-genome sequencing and DNA copy number data sets from The Cancer Genome Atlas to relate chromosomal alterations to imbalances in DNA dosage and describe the landscape of intragenic breakpoints in glioblastoma multiforme (GBM).

Identification of prognostic gene signatures of glioblastoma: a study based on TCGA data analysis.

Background: The Cancer Genome Atlas (TCGA) project is a large-scale effort with the goal of identifying novel molecular aberrations in glioblastoma (GBM).

Methods: Here, we describe an in-depth analysis of gene expression data and copy number aberration (CNA) data to classify GBMs into prognostic groups to determine correlates of subtypes that may be biologically significant.

Results: To identify predictive survival models, we searched TCGA in 173 patients and identified 42 probe sets (P = .

Novel HSP90 inhibitor NVP-HSP990 targets cell-cycle regulators to ablate Olig2-positive glioma tumor-initiating cells.

Genetic heterogeneity and signaling alterations diminish the effectiveness of single-agent therapies in glioblastoma multiforme (GBM). HSP90 is a molecular chaperone for several signaling proteins that are deregulated in glioma cells. Thus, HSP90 inhibition may offer an approach to coordinately correct multiple signaling pathways as a strategy for GBM therapy.

Antitumor activity of NVP-BKM120--a selective pan class I PI3 kinase inhibitor showed differential forms of cell death based on p53 status of glioma cells.

Purpose: The aim of this study was to show preclinical efficacy and clinical development potential of NVP-BKM120, a selective pan class I phosphatidylinositol-3 kinase (PI3K) inhibitor in human glioblastoma (GBM) cells in vitro and in vivo.

Experimental Design: The effect of NVP-BKM120 on cellular growth was assessed by CellTiter-Blue assay. Flow cytometric analyses were carried out to measure the cell-cycle, apoptosis, and mitotic index.

An integrated in vitro and in vivo high-throughput screen identifies treatment leads for ependymoma.

Using a mouse model of ependymoma-a chemoresistant brain tumor-we combined multicell high-throughput screening (HTS), kinome-wide binding assays, and in vivo efficacy studies, to identify potential treatments with predicted toxicity against neural stem cells (NSC). We identified kinases within the insulin signaling pathway and centrosome cycle as regulators of ependymoma cell proliferation, and their corresponding inhibitors as potential therapies. FDA approved drugs not currently used to treat ependymoma were also identified that posses selective toxicity against ependymoma cells relative to normal NSCs both in vitro and in vivo, e.