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145 result(s) for "Zadeh, Gelareh"
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Detection and discrimination of intracranial tumors using plasma cell-free DNA methylomes
Definitive diagnosis of intracranial tumors relies on tissue specimens obtained by invasive surgery. Noninvasive diagnostic approaches provide an opportunity to avoid surgery and mitigate unnecessary risk to patients. In the present study, we show that DNA-methylation profiles from plasma reveal highly specific signatures to detect and accurately discriminate common primary intracranial tumors that share cell-of-origin lineages and can be challenging to distinguish using standard-of-care imaging. A cell-free DNA-methylation sequencing assay accurately identifies different brain tumor types using plasma samples.
Glioblastoma: pathology, molecular mechanisms and markers
Recent advances in genomic technology have led to a better understanding of key molecular alterations that underlie glioblastoma (GBM). The current WHO-based classification of GBM is mainly based on histologic features of the tumor, which frequently do not reflect the molecular differences that describe the diversity in the biology of these lesions. The current WHO definition of GBM relies on the presence of high-grade astrocytic neoplasm with the presence of either microvascular proliferation and/or tumor necrosis. High-throughput analyses have identified molecular subtypes and have led to progress in more accurate classification of GBM. These findings, in turn, would result in development of more effective patient stratification, targeted therapeutics, and prediction of patient outcome. While consensus has not been reached on the precise nature and means to sub-classify GBM, it is clear that IDH -mutant GBMs are clearly distinct from GBMs without IDH1/2 mutation with respect to molecular and clinical features, including prognosis. In addition, recent findings in pediatric GBMs regarding mutations in the histone H3F3A gene suggest that these tumors may represent a 3rd major category of GBM, separate from adult primary ( IDH1/2 wt), and secondary ( IDH1/2 mut) GBMs. In this review, we describe major clinically relevant genetic and epigenetic abnormalities in GBM—such as mutations in IDH1/2 , EGFR , PDGFRA, and NF1 genes—altered methylation of MGMT gene promoter, and mutations in hTERT promoter. These markers may be incorporated into a more refined classification system and applied in more accurate clinical decision-making process. In addition, we focus on current understanding of the biologic heterogeneity and classification of GBM and highlight some of the molecular signatures and alterations that characterize GBMs as histologically defined. We raise the question whether IDH-wild type high grade astrocytomas without microvascular proliferation or necrosis might best be classified as GBM, even if they lack the histologic hallmarks as required in the current WHO classification. Alternatively, an astrocytic tumor that fits the current histologic definition of GBM, but which shows an IDH mutation may in fact be better classified as a distinct entity, given that IDH-mutant GBM are quite distinct from a biological and clinical perspective.
The Diagnosis and Treatment of Pseudoprogression, Radiation Necrosis and Brain Tumor Recurrence
Radiation therapy is an important modality used in the treatment of patients with brain metastatic disease and malignant gliomas. Post-treatment surveillance often involves serial magnetic resonance imaging. A challenge faced by clinicians is in the diagnosis and management of a suspicious gadolinium-enhancing lesion found on imaging. The suspicious lesion may represent post-treatment radiation effects (PTRE) such as pseudoprogression, radiation necrosis or tumor recurrence. Significant progress has been made in diagnostic imaging modalities to assist in differentiating these entities. Surgical and medical interventions have also been developed to treat PTRE. In this review, we discuss the pathophysiology, clinical presentation, diagnostic imaging modalities and provide an algorithm for the management of pseudoprogression, radiation necrosis and tumor recurrence.
Inpatient and outpatient case prioritization for patients with neuro-oncologic disease amid the COVID-19 pandemic: general guidance for neuro-oncology practitioners from the AANS/CNS Tumor Section and Society for Neuro-Oncology
The Coronavirus pandemic has created unprecedented strain on medical resources at health care institutions around the world. At many institutions, this has resulted in efforts to prioritize cases with an attempt to balance the acuity of medical needs with available resources. Here, we provide a framework for institutions and governments to help adjudicate treatment allocations to patients with neuro-oncologic disease.
CIC protein instability contributes to tumorigenesis in glioblastoma
Capicua (CIC) is a transcriptional repressor that counteracts activation of genes downstream of receptor tyrosine kinase (RTK)/Ras/ERK signaling. It is well-established that tumorigenesis, especially in glioblastoma (GBM), is attributed to hyperactive RTK/Ras/ERK signaling. While CIC is mutated in other tumors, here we show that CIC has a tumor suppressive function in GBM through an alternative mechanism. We find that CIC protein levels are negligible in GBM due to continuous proteasome-mediated degradation, which is mediated by the E3 ligase PJA1 and show that this occurs through binding of CIC to its DNA target and phosphorylation on residue S173. PJA1 knockdown increased CIC stability and extended survival using in-vivo models of GBM. Deletion of the ERK binding site resulted in stabilization of CIC and increased therapeutic efficacy of ERK inhibition in GBM models. Our results provide a rationale to target CIC degradation in Ras/ERK-driven tumors, including GBM, to increase efficacy of ERK inhibitors. Capicua (CIC) is a tumour suppressor in oligodendroglioma. Here, the authors show that ERK activation mediates CIC regulation via ubiquitination and degradation by PJA1 and a degradation resistant form of CIC enhances efficacy of ERK inhibition in glioblastoma.
Inhibition of SHP2-mediated dephosphorylation of Ras suppresses oncogenesis
Ras is phosphorylated on a conserved tyrosine at position 32 within the switch I region via Src kinase. This phosphorylation inhibits the binding of effector Raf while promoting the engagement of GTPase-activating protein (GAP) and GTP hydrolysis. Here we identify SHP2 as the ubiquitously expressed tyrosine phosphatase that preferentially binds to and dephosphorylates Ras to increase its association with Raf and activate downstream proliferative Ras/ERK/MAPK signalling. In comparison to normal astrocytes, SHP2 activity is elevated in astrocytes isolated from glioblastoma multiforme (GBM)-prone H-Ras(12V) knock-in mice as well as in glioma cell lines and patient-derived GBM specimens exhibiting hyperactive Ras. Pharmacologic inhibition of SHP2 activity attenuates cell proliferation, soft-agar colony formation and orthotopic GBM growth in NOD/SCID mice and decelerates the progression of low-grade astrocytoma to GBM in a spontaneous transgenic glioma mouse model. These results identify SHP2 as a direct activator of Ras and a potential therapeutic target for cancers driven by a previously ‘undruggable’ oncogenic or hyperactive Ras. Aberrant Ras signalling resulting in downstream Mek/Erk pathway activation is found in many cancers. Here, the authors show that the phosphatase SHP2 dephosphorylates Ras resulting in increased Ras activity, and that increased SHP2 activity is found in glioblastomas.
Programmed death ligand-1 (PD-L1) expression in meningioma; prognostic significance and its association with hypoxia and NFKB2 expression
Management of clinically aggressive meningiomas is a considerable challenge. PD-L1 induced immune suppression has increasingly gained attention in clinical management of cancer; however, to date, the clinical significance and regulatory mechanisms of PD-L1 in meningioma is not yet fully characterized. We sought to characterize PD-L1 expression in meningioma and elucidate its regulatory mechanisms. Immunohistochemical staining of PD-L1 expression in meningiomas showed 43% positivity in both tumor and immune cells and we observed intra and inter tumoral heterogeneity. Univariate and multivariate analyses confirmed that PD-L1 protein expression is an independent prognostic marker for worse recurrence free survival in meningioma. Furthermore, our transcriptomic analysis revealed a strong association between PD-L1 expression and that of NFKB2 and carbonic anhydrase 9 (CA9). We also demonstrated that both of these markers, when co-expressed with PD-L1, predict tumor progression. Our studies on several meningioma cell lines cultured in hypoxic conditions validated the association of CA9 and PD-L1 expression. Here we show the clinical significance of PD-L1 in meningioma as a marker that can predict tumor recurrence. We also show an association PD-L1 expression with NFKB2 expression and its induction under hypoxic conditions. These findings may open new avenues of molecular investigation in pathogenesis of meningioma.
Long-term neurocognitive, psychological, and return to work outcomes in meningioma patients
Introduction This study aimed to investigate long-term neurocognitive, psychological, and return to work (RTW) outcomes in meningioma patients, and to explore whether neurocognitive and psychological factors influence RTW outcomes in this population. Methods In this retrospective study, 61 meningioma patients completed in-depth clinical neuropsychological assessments. Of these participants, 42 were of working-age and had RTW information available following neuropsychological assessment. Seventy-one percent and 80% of patients received radiation and surgery, respectively, with 49% receiving both radiation and surgery. Associations between demographic, medical, neurocognitive, psychological, and RTW data were analyzed using multivariable logistic regression analyses. Results In our sample, 68% of patients exhibited global neurocognitive impairment, with the largest effect sizes found on tests of visual memory ( d  = 0.73), executive function ( d  = 0.61), and attention ( d  = 0.54). Twenty-seven percent exhibited moderate to severe levels of depressive symptoms. In addition, 23% and 30% exhibited clinically significant state and trait anxiety, respectively. Forty-eight percent of patients were unable to RTW. Younger age, faster visuomotor processing speed, and, unexpectedly, higher trait anxiety scores were associated with an increased likelihood of returning to work. Conclusions Meningioma patients are at risk of experiencing neurocognitive deficits, psychological symptoms, and difficulties returning to work. Our results suggest that neurocognitive and psychological factors contribute to RTW status in meningioma patients. Prospective research studies are necessary to increase our understanding of the complexity of functional disability in this growing population.
Clinical significance of checkpoint regulator “Programmed death ligand-1 (PD-L1)” expression in meningioma: review of the current status
IntroductionMeningioma is the most common primary brain tumor. Most meningiomas are benign; however, a subset of these tumors can be aggressive, presenting with early or multiple tumor recurrences that are refractory to neurosurgical resection and radiotherapy. There is no standard systemic therapy for these patients, and post-surgical management of these patients is usually complicated due to lack of accurate prediction for tumor progression.MethodsIn this review, we summarise the crucial immunosuppressive role of checkpoint regulators, including PD-1 and PD-L1 interacting in the tumor microenvironment, which has led to efforts aimed at targeting this axis.ResultsSince their discovery, checkpoint inhibitors have significantly improved the outcome in many types of cancers. Currently, targeted therapy for PD-1 and PD-L1 proteins are being tested in several ongoing clinical trials for brain tumors such as glioblastoma. More recently, there have been some reports implicating increased PD-L1 expression in high-grade (WHO grades II and III) meningiomas. Several clinical trials are underway to assess the efficacy of checkpoint inhibitors in the therapeutic management of patients with aggressive meningiomas. Here, we review the immune suppressive microenvironment in meningiomas, and then focus on clinical and pathological characterization and tumor heterogeneity with respect to PD-L1 expression as well as challenges associated with the assessment of PD-L1 expression in meningioma.ConclusionWe conclude with a brief review of ongoing clinical trials using checkpoint inhibitors for the treatment of high-grade and refractory meningiomas.