Explore the vast range of titles available.

INTRODUCTION Neuritin‐1 (NRN1) was identified as a synaptic protein associated with cognitive resilience to Alzheimer's disease (AD). METHODS Target risk score and cell type expression profiles were generated for NRN1 using methods developed by the Emory‐Sage‐SGC‐JAX Target Enablement to Accelerate Therapy Development for Alzheimer's Disease (TREAT‐AD) Center and Seattle Alzheimer's Disease Brain Cell Atlas (SEA‐AD). Antibody characterization was conducted using Western blots and densitometry to assess the relative protein abundances of NRN1 in rodents, humans, and cell models. RESULTS NRN1 has a TREAT‐AD target risk score of 3.29 out of 5. Based on single‐nucleus RNA sequencing from SEA‐AD, NRN1 expression in excitatory neurons tends to decrease with increasing donor pseudo‐progression. Abcam ab64186 polyclonal NRN1 antibody detects NRN1 protein in vitro and in vivo at molecular weights that suggest NRN1 forms a homodimer. NRN1 protein abundance is comparable among controls and primary tauopathy cases, as well as Tau P301S mice and non‐transgenic littermates at 3 and 9 months. DISCUSSION These findings advance the investigation of NRN1 as a therapeutic candidate for AD. Highlights NRN1 is associated with cognitive resilience to AD. Based on snRNA‐seq from SEA‐AD, NRN1 expression in excitatory neurons tends to decrease with increasing donor pseudo‐progression. Abcam ab64186 polyclonal NRN1 antibody detects NRN1 protein in vitro and in vivo at molecular weights that suggest NRN1 forms a homodimer. NRN1 protein abundance is comparable among controls and primary tauopathy cases, as well as Tau P301S mice and non‐transgenic littermates at 3 and 9 months.

The gold standard assay for radiation response is the clonogenic assay, a normalized colony formation assay (CFA) that can capture a broad range of radiation-induced cell death mechanisms. Traditionally, this assay relies on two-dimensional (2D) cell culture conditions with colonies counted by fixing and staining protocols. While some groups have converted these to three-dimensional (3D) conditions, these models still utilize 2D-like media compositions containing serum that are incompatible with stem-like cell models such as brain tumor initiating cells (BTICs) that form self-aggregating spheroids in neural stem cell media. BTICs are the preferred patient-derived model system for studying glioblastoma (GBM) as they tend to better retain molecular and phenotypic characteristics of the original tumor tissue. As such, it is important that preclinical radiation studies should be adapted to BTIC conditions. In this study, we describe a series of experimental approaches for performing CFA experiments with BTIC cultures. Our results indicate that serum-free clonogenic assays are feasible for combination drug and radiation testing and may better facilitate translatability of preclinical findings.

Glioblastoma (GBM) is the most common and deadly primary brain tumor in adults. While in vitro patient-derived xenografts (PDX) lines are useful for studying GBM, they often exclude astrocytes and macrophages, which contribute significantly to tumor growth, invasion, and chemoradioresistance. Integrating these cells into tumor models is difficult due to their need for serum, which triggers GBM-PDX lines to lose their stem-like properties. The aim of this study was to develop a serum-free triculture model of GBM-PDX lines, normal human astrocytes (NHAs), and macrophages. Serum-free media alternatives were formulated for NHAs and identified for THP-1 macrophages, then combined with GBM PDX media to establish “PSX,” an experimental maintenance media. Cells were transitioned to serum-free media alternatives and functionally assessed through several parameters unique to each cell type. In addition to assessing GBM “stemness,” a custom 350-gene NanoString chip was used to assess differential gene expression in monocultured PDX cells versus PDX cells exposed to NHAs and macrophages. PSX maintained canonical function in astrocytes and macrophages while preserving the stem-like properties of GBM-PDX cells. Tri-culturing all three cells increased the expression of stemness-associated transcription factors and increased the expression of genes related to stemness and hypoxia in GBM cells. GBM PDX cells exposed to NHAs and macrophages in direct triculture exhibit increases in markers of stemness and hypoxia. These findings suggest that the serum-free triculture model presented herein may better recapitulate the tumoral heterogeneity of GBM in vitro, providing a novel model to utilize in current research.

Radiotherapy is involved in 50% of all cancer treatments and 40% of cancer cures. Most of these treatments are delivered in fractions of equal doses of radiation (Fractional Equivalent Dosing (FED)) in days to weeks. This treatment paradigm has remained unchanged in the past century and does not account for the development of radioresistance during treatment. Even if under-optimized, deviating from a century of successful therapy delivered in FED can be difficult. One way of exploring the infinite space of fraction size and scheduling to identify optimal fractionation schedules is through mathematical oncology simulations that allow for in silico evaluation. This review article explores the evidence that current fractionation promotes the development of radioresistance, summarizes mathematical solutions to account for radioresistance, both in the curative and non-curative setting, and reviews current clinical data investigating non-FED fractionated radiotherapy.

Glioblastoma (GBM) is the most common primary brain malignancy in adults and the gradual development of treatment resistance prevents patients from achieving remission. A primary objective in the field is to devise strategies to overcome this. We predicted this could be achieved by improving existing therapies, creating better models to study GBM, and by identifying a potential therapeutic target.Fractionated radiotherapy (RT) has been used in GBM standard of care for over a century but does not account for GBM heterogeneity. We first hypothesized that in silico mathematical modeling would be a useful tool for cytotoxicity prediction. While this model had been investigated before, it remained elusive if the predictions translated to physiological systems. We used three patient-derived brain tumor-initiating cell (BTIC) xenolines with differential RT-sensitivity and a novel longitudinal imaging assay to answer this question. Key findings in this study revealed delivering RT in ramped down fractions overcame acquired radioresistance more efficiently than delivering equivalent fractions.Next, we aimed to design an improved pre-clinical in vitro model that better recapitulated GBM heterogeneity. We predicted this could be accomplished by formulating a special maintenance media that supports the stemness properties of BTICs and the canonical functions of astrocytes and macrophages. We validated our model using gold standard functionality assays and differential gene expression analysis which revealed our triculture model recapitulates GBM signatures better than GBM monocultures.Finally, we aimed to uncover a therapeutic target and mechanism. Tunneling nanotubes (TNT) are exciting due to their novelty, multifaceted utility in cellular processes, and therapeutic potential. In this study we aimed to elucidate the role of Myristoylated Alanine-Rich C Kinase Substrate (MARCKS) in the regulation of TNTs between GBM cells and astrocytes. Our results revealed TNT formation is influenced by PKC activation, MARCKS expression, and phosphorylation. Importantly, we were able to target the TNTs with a cytotoxic peptide derived from the effector domain of MARCKS, revealing therapeutic potential.In summation, the work presented in this thesis is geared towards assessing three key hypotheses that share the common goal of contributing to the attenuation of therapeutic resistance.