Citations

Abstract BACKGROUND Diffuse midline gliomas (DMGs) and posterior fossa group A (PFA) ependymomas are aggressive pediatric brain tumors. Most DMGs harbor histone H3.3K27M or G34R mutations, or exhibit EZHIP overexpression. With a median survival of just 9–15 months, DMGs are among the most lethal human cancers. PFAs, nearly universally overexpress EZHIP and have a 5-year survival rate of ~50%. Unlike K27M or EZHIP-overexpressing DMGs, G34R-mutant tumors retain H3K27me3. METHODS Using the RCAS/Nestin-TVA system, we introduced H3.3 K27M–, G34R–, or S31A–P2A–PDGFβ or H3.3WT–P2A–PDGFβ into neonatal mice. Controls included, histone mutants EZHIP alone and ΔEZHIP (PRC2-binding-deficient). Tumor bearing mice were assessed for incidence, grade, survival, and H3K27me3 and H3.3S31P status. RESULTS H3.3K27M, G34R, and S31A–P2A–PDGFβ induced high-grade gliomas with significantly reduced survival (p < 0.001). Mechanistically, G34R—like K27M—reduced mitotic Ser31 phosphorylation (S31P), causing chromosomal instability and impaired p53 checkpoint function. S31A directly modeled loss of S31P and similarly drove high-grade tumor formation. H3.3WT–P2A–PDGFβ induced only low-grade lesions. EZHIP–P2A–PDGFβ enhanced tumor grade but not survival; only EZHIP fully abolished H3K27me3. ΔEZHIP and all unlinked constructs were non-tumorigenic. CONCLUSION These models establish a robust platform to dissect glioma drivers and chromatin vulnerabilities. We previously showed that H3.3K27M reduces S31P, promoting chromosomal instability and impaired p53 function. We now demonstrate that H3.3G34R also reduces S31P and drives tumor formation in vivo. Direct loss of S31P via H3.3S31A is likewise sufficient for gliomagenesis. Although EZHIP does not alter S31P, it promotes genome instability through distinct mechanisms—disrupting PALB2–BRCA2-mediated DNA repair and mislocalizing TopoIIα, a process dependent on H3K27me3. H3.3K27M, G34R, and EZHIP thus converge on genome instability through distinct pathways. This platform supports mechanistic and therapeutic studies and is now being expanded using tetracycline-regulated expression to investigate tumor maintenance.

Abstract Diffuse midline and diffuse hemispheric glioma contain the driver mutations H3.3 K27M and G34R/V, respectively. These mutations alter histone methylations, suggesting that dysregulation of gene expression may contribute to tumor formation. We recently reported that these mutations also inhibit the phosphorylation of H3.3 at Serine 31. Importantly, H3.3 S31A mice developed high-grade gliomas – similar to those from G34R and K27M mice – indicating that loss of phosphoS31 promotes gliomagenesis. Chk1, a key kinase in DNA damage response and mitotic fidelity, phosphorylates H3.3 S31. H3.3 S31 is phosphorylated at the pericentromere in metaphase and is typically absent during interphase. Reduction of S31 phosphorylation by H3.3 K27M, G34R, G34V, or S31A was sufficient to induce mitotic errors leading to aneuploidy. Using CRISPR/Cas9, we generated novel H3.3 WT/WT and WT/S31A lines from glioma patient-derived SF-8628 (H3.3 WT/K27M) and KNS-42 (H3.3 WT/G34V) cells. Immunofluorescence of metaphase spreads revealed H3.3 phosphoS31 at the pericentromeres as expected. Interestingly, total Chk1 and active Chk1 (pS296) were significantly enriched at the pericentromeres of H3.3 K27M and G34V cells, as compared to H3.3 WT cells. While total ATR and active ATR (pT1989) were present at the pericentromere, their levels were unaltered by the H3.3 mutations. Surface plasmon resonance of purified proteins revealed that Chk1 has two binding affinities for H3.3 - likely corresponding to the previously identified Chk1 phosphorylation sites (T11 and S31) on H3.3. Chk1 binding at one site was unaffected by H3.3 K27M, while the second site showed an altered dissociation from H3.3 K27M. In summary, our data suggest that the low pericentromeric pS31 levels associated with H3.3 glioma mutations result from Chk1 recognizing the mutant histone, but without completing a phosphorylation cycle, becoming trapped at the pericentromere. This result suggests that H3.3 mutations, by trapping Chk1, may impede Chk1 activities beyond just reducing H3.3 phosphorylation.

Abstract BACKGROUND Posterior fossa group A ependymomas (PFAs) and diffuse midline gliomas (DMGs) are lethal pediatric brain tumors characterized by global loss of H3K27me3. This epigenetic disruption is caused by either EZHIP overexpression or H3.1/H3.3K27M mutations, which are mutually exclusive. EZHIP is aberrantly expressed in nearly all PFAs and approximately 10% of DMGs, while K27M mutations are found in ~80% of DMGs. In normal development, EZHIP expression is restricted to primordial germ cells during meiosis. We used human neural stem cells (NSCs), which give rise to ependymal and oligodendrocyte precursor lineages, to model EZHIP’s developmental effects. These cell types reflect the likely cells of origin for PFAs and DMGs, making them a biologically relevant platform to interrogate early tumorigenic mechanisms. METHODS AND RESULTS EZHIP was expressed in NSCs, astrocytes, and DMG lines. In NSCs, EZHIP induced strong repression of genome stability and mitotic fidelity genes, confirmed by gene set enrichment analysis (NES –2.91, p = 1e–10), and activated stem-like developmental programs. This repression was not observed in differentiated cells or tumor lines, indicating an NSC-specific vulnerability. The repressed targets were highly enriched for E2F-regulated genes (NES –3.61, p = 1e–10). EZHIP-expressing NSCs showed reduced DNA repair capacity, mitotic abnormalities, and continued proliferation. EZHIP is known to impair double-strand break repair by binding PALB2 and blocking BRCA2 recruitment, and to disrupt TopoIIα localization via H3K27me3 depletion, compounding mitotic stress in NSCs. CONCLUSIONS EZHIP disrupts genome maintenance and promotes transformation selectively in neural progenitors during a defined developmental window. Published data show that H3.3K27M induces profound transcriptional reprogramming in week 13 human NSCs, but these effects are diminished or absent by week 19, suggesting a shared, time-limited window of epigenetic vulnerability in both H3K27M- and EZHIP-driven tumors. Understanding this context-dependent repression has important implications for identifying stage-specific therapeutic vulnerabilities in pediatric gliomas.

Abstract Background The associations between different types of diabetes, characterized by distinct pathophysiology and genetic architecture, and pancreatic ductal adenocarcinoma (PDAC) risk are not understood. Methods We investigated associations of genetic susceptibility to type 2 diabetes (T2D), 8 T2D mechanistic clusters, type 1 diabetes (T1D), and maturity-onset diabetes of the young (MODY) with PDAC risk. We used genome-wide association study (GWAS) summary-level statistics for T2D (242 283 cases, 1 569 734 controls), T1D (18 942 cases, 501 638 controls), and PDAC (10 244 cases and 360 535 controls) in individuals of European ancestry. Results Two-sample Mendelian randomization (MR) using the Robust Adjusted Profile Score (MR-RAPS) method indicated that genetically predicted T2D was associated with PDAC risk (OR = 1.10; 95% CI = 1.05 to 1.15), particularly the T2D obesity (OR = 1.28; 95% CI = 1.15 to 1.42) and lipodystrophy (OR = 1.25; 95% CI = 1.03 to 1.51) clusters. No association was observed for T1D with PDAC risk (OR = 1.01; 95% CI = 0.99 to 1.02). Pathway/gene-set analysis using the summary-based Adaptive Rank Truncated Product (sARTP) method revealed a significant association between the MODY gene-sets and PDAC risk (P = 1.5 × 10−8), which remained after excluding 20 known PDAC GWAS loci (P = 7.6 × 10−4). HNF1A, FOXA3, and HNF4A were the top contributing genes after excluding the previously identified GWAS loci regions. Conclusions Our results from this genetic association study support that T2D, particularly the obesity and lipodystrophy mechanistic clusters, and MODY genomic susceptibility regions play a role in the etiology of PDAC.

Background: Internalized HIV stigma (IHS) is associated with reductions in antiretroviral therapy (ART) adherence and HIV viremia mediated through depression. However, there is still a need to quantify the direct impact of IHS on ART adherence to inform interventions to improve medication adherence. Methods: The Center for AIDS Research Network of Integrated Clinical Systems is a longitudinal, US-based, multisite cohort of people with HIV who complete patient-reported outcome assessments as part of HIV-care visits. Patient-reported outcome data include IHS items, ART adherence, depression assessments, substance use, and other outcomes. We examined associations between IHS and ART adherence using generalized linear latent and mixed models with a nonparametric random effects intercept to accommodate repeated measures. Results were compared with analyses using generalized estimating equations and marginal structural models. Results: Among 13,119 people with HIV, the mean age was 47.4 years, 17.6% were women, and 59.3% were non-White. Across 33,139 observations, controlled for repeated measures on individuals, HIV medication adherence was reduced by 1.07% for every point increase in IHS after controlling for age, sex, ethnicity, geographic location, and substance use, and 0.58% when additionally adjusted for depression score. Marginal structural models and generalized estimating equations provided similar results. Conclusions: Our study demonstrates that IHS has a direct association with reductions in ART adherence, which could affect other comorbid health outcomes that are influenced by unsuppressed viremia over time. Developing a thorough understanding of the mechanisms through which IHS affects ART adherence is critical for developing interventions to mitigate IHS and improve health outcomes across the lifespan.

Abstract Repetitive head impacts are common in contact and collision sports and are linked to structural brain changes and an elevated risk of neurodegenerative diseases such as Chronic Traumatic Encephalopathy. Identifying early in vivo structural markers remains challenging. Although diagnosis currently requires post-mortem confirmation, clinical symptoms, including cognitive impairment and behavioural changes, are reflected in the diagnosis of Traumatic Encephalopathy Syndrome. These symptoms align with dysfunction in key brain regions—amygdala, hippocampus and thalamus—which support memory, emotion and behaviour and commonly show tau pathology in Chronic Traumatic Encephalopathy. This study uses shape analysis to examine structural differences in these regions between former American football players and unexposed asymptomatic controls and evaluates the influence of age, head impact exposure and clinical diagnosis on brain structure. We analyzed brain morphology in former American football players (n = 163) and unexposed, asymptomatic controls (n = 53). Structural segmentation was performed with FreeSurfer 7.1, and the shape analysis pipeline was used to generate subregional reconstructions. Vertex-level morphometry, based on the logarithm of the Jacobian determinant and radial distance, quantified local surface area dilation and thickness. Group differences were examined with covariate-adjusted linear regression models contrasting football players and controls, as well as participants with and without a Traumatic Encephalopathy Syndrome diagnosis. Partial correlations examined the influence of age, age of first football exposure and cumulative head impact index metrics, including frequency, linear acceleration and rotational force. Models were adjusted accordingly for age, body mass index, education, race, imaging site, apolipoprotein ϵ4 status and total intracranial volume. Former football players exhibited bilateral surface area contractions in the hippocampus and amygdala, along with reduced amygdala thickness, compared to controls. Older age was associated with widespread surface contractions and thinning across all regions, except for preserved thickness in the left hippocampus. An earlier age of first exposure to football correlated with surface contractions in the thalamus and left hippocampus. Greater cumulative linear acceleration was linked to bilateral hippocampal surface contractions and reduced thickness in the left thalamus, while greater rotational force exposure was associated with hippocampal thinning. No significant structural differences were found between players with and without a diagnosis of Traumatic Encephalopathy Syndrome. These findings extend volume-based research by revealing localized alterations in surface area dilation and thickness and emphasize the roles of age and repetitive head impact exposure in long-term brain changes.

Background: Ventricular tachycardia (VT) is a major contributor to death among ischemic heart disease (IHD) patients. In this systematic review and meta-analysis, we evaluate the efficacy of catheter ablation in patients with ischemic cardiomyopathy. Methods: We conducted a meta-analysis by searching the electronic database up to April 2025. Seven studies, including 1192 patients, were identified. A random-effect model was used to estimate pooled risk ratios (RRs) and 95% confidence intervals (CIs). Trial sequential analysis was conducted to assess sample size adequacy. Results: Among Ischemic heart disease patients with ICDs, VT ablation was associated with a significant reduction in ICD shocks (RR = 0.50, 95% CI [0.34–0.74]), a trend toward reduced VT storm (RR = 0.64, 95% CI [0.40–1.04], p = 0.07), and lower rates of cardiovascular hospitalization (RR = 0.73, 95% CI [0.53–1.01], p = 0.06) compared to ICD alone. However, no significant differences were observed when compared to patients receiving ICD plus antiarrhythmic drugs (AADs). Additionally, VT ablation showed no significant impact on mortality or VT/VF recurrence compared to either ICD alone or ICD with AADs. Trial Sequential Analysis provided conclusive evidence for VT/VF recurrence outcomes, while further data are required for other outcomes. Conclusion: Among ischemic heart disease patients with ICD, VT ablation reduces ICD shocks, VT storm, and cardiovascular hospitalizations compared to ICD-only, but offers no significant advantage over ICD combined with antiarrhythmic drugs. VT ablation does not impact mortality or the recurrence of VT/VF. Trial Sequential Analysis confirmed conclusive evidence for VT/VF recurrence, while additional data is needed for other outcomes.

Abstract Background In the current clinical workflow of radiation oncology, therapists manually summarize the physician‐issued Computed Tomography (CT) simulation orders to prepare patients' CT simulations. This process increases the workload, introduces variability in documentation quality, and is prone to human errors. Purpose This study aims to address these challenges using a large language model (LLM) to automate the generation of summaries from the CT simulation orders and evaluate its performance. Methods A total of 607 CT simulation orders were collected from the Aria database at our institution. A locally hosted LLaMa 3.1 405B model, accessed via the Application Programming Interface (API) service, was used to extract keywords from the CT simulation orders and generate summaries. The downloaded CT simulation orders were categorized into seven groups based on treatment modalities and disease sites. For each group, a customized instruction prompt was developed collaboratively with therapists to guide the LLaMa 3.1 405B model in generating summaries. The ground truth for the corresponding summaries was manually derived by carefully reviewing each CT simulation order and subsequently verified by therapists. The accuracy of the LLM‐generated summaries was evaluated by therapists using the ground truth. Results Over 98% of the LLM‐generated summaries aligned with the ground truth in terms of accuracy. Our evaluations showed an improved consistency in format and enhanced readability from the LLM‐generated summaries compared to the corresponding therapist‐generated summaries. This automated approach demonstrated consistent performance across all groups, regardless of treatment modality or disease site. Conclusions This study demonstrated the high precision and consistency of the LLaMa 3.1 405B model in extracting keywords and summarizing CT simulation orders, suggesting that LLMs have great potential to assist in this task, reduce the workload of CT simulation therapists and improve radiation oncology workflow efficiency.