Publications by authors named "Ryan T Nitta"

Article Synopsis
  • Glioblastoma (GBM) is a difficult-to-treat brain cancer characterized by aggressive behavior and high rates of recurrence, with tumor-associated microglia and macrophages (TAM) playing a significant role in its immune microenvironment.
  • Researchers found that TAMs in the tumor core show higher ATP synthase expression and activity, leading to increased energy production and metabolic changes in the presence of GBM cells, which in turn stimulate tumor growth.
  • Targeting the signaling pathway involving elevated extracellular ATP (eATP) and the P2X purinoceptor 7 (P2X7R) has the potential to decrease tumor growth and improve survival rates in models of GBM, highlighting a new therapeutic strategy.
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Regulatory T cells (Treg) are important players in the tumor microenvironment. However, the mechanisms behind their immunosuppressive effects are poorly understood. We found that CCR6-CCL20 activity in tumor-infiltrating Tregs is associated with greater glycolytic activity and ablation of Ccr6 reduced glycolysis and lactic acid production while increasing compensatory glutamine metabolism.

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Objective: Medulloblastoma (MB) is the most common malignant pediatric brain tumor and accounts for approximately 20% of all pediatric CNS tumors. Current multimodal treatment is associated with a 70%-90% 5-year survival rate; however, the prognosis for patients with tumor dissemination and recurrent MB remains poor. The majority of survivors exhibit long-term neurocognitive complications; thus, more effective and less toxic treatments are critically needed.

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The original version of this Article contained an error in the spelling of the author David Solow-Cordero, which was incorrectly given as David Solow-Codero. This has now been corrected in both the PDF and HTML versions of the Article.

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Among high-grade brain tumors, glioblastoma is particularly difficult to treat, in part due to its highly infiltrative nature which contributes to the malignant phenotype and high mortality in patients. In order to better understand the signaling pathways underlying glioblastoma invasion, we performed the first large-scale CRISPR-Cas9 loss of function screen specifically designed to identify genes that facilitate cell invasion. We tested 4,574 genes predicted to be involved in trafficking and motility.

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Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Since surviving patients experience severe neurocognitive disabilities, better and more effective treatments are needed to enhance their quality of life. Casein kinase 2 (CK2) is known to regulate cell growth and survival in multiple cancers; however, the role of CK2 in MB is currently being studied.

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Medulloblastoma is the most common malignant brain tumor of childhood. Group 3 medulloblastoma, the most aggressive molecular subtype, frequently disseminates through the leptomeningeal cerebral spinal fluid (CSF) spaces in the brain and spinal cord. The mechanism of dissemination through the CSF remains poorly understood, and the molecular pathways involved in medulloblastoma metastasis and self-renewal are largely unknown.

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A variety of drugs targeting monoamine receptors are routinely used in human pharmacology. We assessed the effect of these drugs on the viability of tumor-initiating cells isolated from patients with glioblastoma. Among the drugs targeting monoamine receptors, we identified prazosin, an α1- and α2B-adrenergic receptor antagonist, as the most potent inducer of patient-derived glioblastoma-initiating cell death.

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Background: Glioblastoma (GBM) is the most malignant primary brain tumor in adults, with a median survival time of one and a half years. Traditional treatments, including radiation, chemotherapy, and surgery, are not curative, making it imperative to find more effective treatments for this lethal disease. γ-Glutamyl transferase (GGT) is a family of enzymes that was shown to control crucial redox-sensitive functions and to regulate the balance between proliferation and apoptosis.

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Casein kinase 2 (CK2) is an oncogenic protein kinase which contributes to tumor development, proliferation, and suppression of apoptosis in multiple cancer types. The mechanism by which CK2 expression and activity leads to tumorigenesis in glioblastoma (GBM), a stage IV primary brain tumor, is being studied. Recent studies demonstrate that CK2 plays an important role in GBM formation and growth through the inhibition of tumor suppressors and activation of oncogenes.

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The purpose of this article is to update the neurosurgical field on current molecular markers important to glioblastoma biology, treatment, and prognosis. The highlighted biologic markers in this article include epidermal growth factor receptor (EGFR), EGFR variant III (EGFRvIII), phosphatase and tensin homolog deleted on chromosome 10 (PTEN), and O6-methylguanine-DNA methyltransferase (MGMT).

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Article Synopsis
  • EGFRvIII is a variant of the epidermal growth factor receptor primarily found in glioblastoma, but this study explores its presence in primary breast carcinoma.
  • The study confirmed the presence of EGFRvIII in breast cancer without any amplification or rearrangement of the EGFR gene, and noted that cells with EGFRvIII showed traits linked to cancer stem cells and enhanced tumor formation.
  • EGFRvIII's influence on breast cancer stem cell characteristics is mediated through the Wnt/β-catenin signaling pathway, and inhibiting this pathway can reverse its effects, highlighting a new role for EGFRvIII in breast tumor development.
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Despite numerous clinical trials over the past 2 decades, the overall survival for children diagnosed with diffuse intrinsic pontine glioma (DIPG) remains 9-10 months. Radiation therapy is the only treatment with proven effect and novel therapies are needed. Epidermal growth factor receptor variant III (EGFRvIII) is the most common variant of the epidermal growth factor receptor and is expressed in many tumor types but is rarely found in normal tissue.

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The c-Jun N-terminal kinases (JNK) are important regulators of cell growth, proliferation, and apoptosis. JNKs are typically activated by a sequence of events that include phosphorylation of its T-P-Y motif by an upstream kinase, followed by homodimerization and translocation to the nucleus. Constitutive activation of JNK has been found in a variety of cancers including non-small cell lung carcinomas, gliomas, and mantle cell lymphoma.

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Background: EGF receptor variant III (EGFRvIII) is the most common variant of the EGF receptor observed in human tumors. It results from the in frame deletion of exons 2-7 and the generation of a novel glycine residue at the junction of exons 1 and 8. This novel juxtaposition of amino acids within the extra-cellular domain of the EGF receptor creates a tumor specific and immunogenic epitope.

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c-Jun N-terminal kinases (JNKs) are part of the mitogen-activated protein kinase (MAPK) family and are important regulators of cell growth, proliferation, and apoptosis. Typically, a sequential series of events are necessary for MAPK activation: phosphorylation, dimerization, and then subsequent translocation to the nucleus. Interestingly, a constitutively active JNK isoform, JNK2alpha2, possesses the ability to autophosphorylate and has been implicated in several human tumors, including glioblastoma multiforme.

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Background: A-type lamins, predominantly lamins A and C, are nuclear intermediate filaments believed to act as scaffolds for assembly of transcription factors. Lamin A/C is necessary for the retinoblastoma protein (pRB) stabilization through unknown mechanism(s). Two oncoproteins, gankyrin and MDM2, are known to promote pRB degradation in other contexts.

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Mutations in the LMNA gene, which encodes all A-type lamins, including lamin A and lamin C, cause a variety of tissue-specific degenerative diseases termed laminopathies. Little is known about the pathogenesis of these disorders. Previous studies have indicated that A-type lamins interact with the retinoblastoma protein (pRB).

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The retinoblastoma protein (pRB) is a critical regulator of cell proliferation and differentiation and an important tumor suppressor. In the G(1) phase of the cell cycle, pRB localizes to perinucleolar sites associated with lamin A/C intranuclear foci. Here, we examine pRB function in cells lacking lamin A/C, finding that pRB levels are dramatically decreased and that the remaining pRB is mislocalized.

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