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Results for “high-grade astrocytoma”

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PubMed2026

Targeting SUV4-20H2-mediated H4K20 methylation restrains growth and migration in pediatric high-grade astrocytomas.

Pediatric astrocytomas are characterized by increased molecular and clinical heterogeneity with epigenetic alterations contributing to aggressiveness and therapy resistance. The repressive histone mark H4K20 trimethylation (H4K20me3) and the methyltransferase SUV4-20H2 (KMT5C) are critical regulators of chromatin integrity and genome stability, with limited investigation in pediatric astrocytomas. KMT5C mRNA levels were evaluated in a publicly available pediatric gliomas database using bioinformatic analysis. Investigation of SUV4-20H2 and H4K20me3 expression was performed in a cohort of 43 pediatric astrocytoma tissues by immunohistochemistry. Their functional role and mechanism of action was investigated in pediatric glioma cell lines by using the substrate-competitive inhibitor of SUV4-20, A-196. Cell viability, apoptosis and migration were assessed using XTT, cleaved PARP, and wound healing assays, respectively. Effects of treatment on H4K20 methylation, DNA damage, mitotic stress [Polo-like kinase (PLK1) expression], and invasion markers (N-cadherin, β-catenin expression) were examined by western immunoblotting. KMT5C mRNA was significantly enriched in pediatric high-grade astrocytomas compared to low-grade tumors. A significant elevation of SUV4-20H2 and H4K20me3 expression was detected in astrocytoma tissues indicating epigenetic dysregulation contributing to malignancy. Treatment with A-196 reduced cell proliferation of pediatric glioma cell lines and induced apoptosis in a dose-dependent manner. It further impaired cell migration, accompanied by reduced N-cadherin and β-catenin expression. Mechanistically, inhibition of SUV4-20 depleted H4K20me3, inducing chromatin destabilization, replication-associated DNA damage and was associated with increased PLK1 expression, consistent with activation of a mitotic stress response. Our findings indicate that SUV4-20H2-mediated H4K20 activity in pediatric high-grade astrocytomas maintains their growth and migratory potential by regulating chromatin integrity and may serve as potential therapeutic target.

H4K20me2/3↗

PubMed2026

High-grade astrocytoma with piloid features: a clinical and genomic analysis of prognostic factors using a large cohort.

BACKGROUND: High-grade astrocytoma with piloid features (HGAP) is a recently defined tumor type that is not well-understood. Prognostic factors of clinical outcomes are not well-established. METHODS: Methylation profiling was performed on tumor samples, many at the National Cancer Institute (NCI) Laboratory of Pathology, and others from publicly available sources. Methylation classifier scores of ≥ 0.90 to the HGAP class on the NCI-Bethesda classifier version 3 were included. Clinical features were collected from the medical record. Survival analyses were performed using the Kaplan-Meier and Cox-proportional hazards methods. RESULTS: The cohort comprised 421 patients. There were high rates of ATRX alteration (62%), CDKN2A/B homozygous loss (78%) and MGMT promoter methylation (53%). MAPK alterations were identified in 74% of evaluable samples. The median age was 46 years, and posterior fossa location was predominant (52%). The median overall survival (OS) was 88 months. Older age (p = 0.01) and the presence of an ATRX alteration (p = 0.04) were found to be negative prognostic factors. The presence of cystic features on magnetic resonance imaging (MRI) was found to be favorably prognostic (p = 0.01). Factors that were not significantly associated with prognosis included histologic high-grade features, CDKN2A/B homozygous deletion, MGMT promoter methylation, extent of resection, and presence of NF1 syndrome. CONCLUSIONS: This large cohort establishes relative frequencies of several important markers. Additionally, older age, the presence of an ATRX alteration, and cystic features on MRI were found to be prognostic. Our work may aid in optimizing treatment regimens for patients with this tumor type.

ATRX alteration↗

PubMed1979

Preoperative radiotherapy and chemotherapy in hypervascular, high-grade supratentorial astrocytomas.

From a group of ten patients with hypervascular, high-grade, supratentorial astrocytomas, five were treated with pre-operative radiotherapy alone, and five with radiotherapy in combination with cytostatic drugs. The aim was to investigate the timing of intracranial operations in the multimodality therapy of brain tumors. The tumor size was diminished only in one case, but tumor vascularization was reduced in half of the cases by the pre-operative treatment. Survival was not improved. Surgical treatment still should be the first of the therapeutic measures. Pre-operative radiotherapy may be of value to reduce tumor vascularization in hypervascular, centrally localized tumors.

Adult↗

PubMed1978

Radiotherapy combined with procarbazine, bleomycin, and CCNU in the treatment of high-grade supratentorial astrocytomas.

Twenty consecutive patients with supratentorial Grade III and IV astrocytomas were treated with postoperative radiotherapy, and a simultaneous induction chemotherapy with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), procarbazine, bleomycin, and maintenance chemotherapy with CCNU. They were compared to 32 retrospective control patients selected similarly, who had received postoperative radiation therapy alone. The median survival time was 56 weeks for the combined treatment group, and 51 weeks for the control group. There was no statistical difference in survival in the two groups of patients.

Adolescent↗

PubMed1977

Chemotherapeutic trials on human malignant astrocytomas in organ culture.

A technique of organ culture based on a three-dimensional porous matrix was employed for chemotherapeutic trials on human malignant astrocytomas. The method allows neoplasms to retain the morphological identity and the histological characteristics they possess in vivo. Success in culture was greatest with high-grade astrocytomas, the majority of which showed definite infiltration of the matrix. Low-grade tumors, if viable, did not display active penetration. Drug trials on eight malignant astrocytomas included BCNU, methyl CCNU, VP 16-213, and Solu-Medrol. Cyanide and luciferase were used as experimental metabolic toxins. Evidence of cytotoxicity was assesed qualitatively by histological changes on microscopic preparations of treated and control cultures. Microfluorometric determinations of reduced nicotinamide adenine dinucleotide (NADH) were applied to these trials in an effort to detect a quantitative biochemical index of drug effects. A variable rise in although correlation with microscopic changes was inconsistent. Because of its potential merits, organ culture may be a valuable tool for further work on pharmacological management of malignant gliomas.

Antineoplastic Agents↗

PubMed2026

Spindle Cell Predominant Anaplastic Pleomorphic Xanthoastrocytoma (WHO Grade 3) With Focal Piloid Features: A Rare Case Study With Comprehensive Molecular Profiling.

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic tumor of the central nervous system. The typical form demonstrates relatively low-grade histologic features, whereas an anaplastic variant shows more aggressive behavior, including increased mitotic activity and necrotic changes. These tumors are often associated with alterations involving key growth signaling pathways and cell cycle regulatory genes, with molecular features that may resemble those seen in other high-grade astrocytic neoplasms. We describe an unusual example of an anaplastic pleomorphic xanthoastrocytoma showing focal piloid differentiation. The patient presented with acute neurologic symptoms, and imaging demonstrated a large, enhancing, well-circumscribed cerebral lesion with limited surrounding edema. Histologic evaluation revealed a highly cellular astrocytic neoplasm composed of spindle-shaped cells with marked pleomorphism, including scattered multinucleated forms, brisk mitotic activity, and necrotic areas. At the periphery, regions with elongated bipolar glial cells and occasional cytoplasmic inclusions suggestive of piloid morphology were identified. Molecular analysis demonstrated an activating alteration in the mitogen-activated protein kinase (MAPK) pathway along with additional genomic abnormalities, while mutations commonly associated with diffuse gliomas were not detected. The presence of piloid features within an otherwise anaplastic tumor is rare and may be relevant to the relatively favorable outcome observed during extended follow-up.

anaplastic↗

PubMed2025

Longitudinal profiling of IDH-mutant astrocytomas reveals acquired RAS-MAPK pathway mutations associated with inferior survival.

BACKGROUND: Isocitrate dehydrogenase (IDH)-mutant astrocytomas represent the most frequent primary intraparenchymal brain tumor in young adults, which typically arise as low-grade neoplasms that often progress and transform to higher grade despite current therapeutic approaches. However, the genetic alterations underlying high-grade transformation and disease progression of IDH-mutant astrocytomas remain inadequately defined. METHODS: Genomic profiling was performed on 205 IDH-mutant astrocytomas from 172 patients from both initial treatment-naive and recurrent post-treatment tumor specimens. Molecular findings were integrated with clinical outcomes and pathologic features to define the associations of novel genetic alterations in the RAS-MAPK signaling pathway. RESULTS: Likely oncogenic alterations within the RAS-MAPK mitogenic signaling pathway were identified in 13% of IDH-mutant astrocytomas, which involved the KRAS, NRAS, BRAF, NF1, SPRED1, and LZTR1 genes. These included focal amplifications and known activating mutations in oncogenic components (e.g. KRAS, BRAF), as well as deletions and truncating mutations in negative regulatory components (e.g. NF1, SPRED1). These RAS-MAPK pathway alterations were enriched in recurrent tumors and occurred nearly always in high-grade tumors, often co-occurring with CDKN2A homozygous deletion. Patients whose IDH-mutant astrocytomas harbored these oncogenic RAS-MAPK pathway alterations had inferior survival compared to those with RAS-MAPK wild-type tumors. CONCLUSIONS: These findings highlight novel genetic perturbations in the RAS-MAPK pathway as a likely mechanism contributing to the high-grade transformation and treatment resistance of IDH-mutant astrocytomas that may be a potential therapeutic target for affected patients and used for future risk stratification.

IDH1 mutation↗