Histone serotonylation regulates ependymoma tumorigenesis.

Bidirectional communication between tumours and neurons has emerged as a key facet of the tumour microenvironment that drives malignancy1,2. Another hallmark feature of cancer is epigenomic dysregulation, in which alterations in gene expression influence cell states and interactions with the tumour microenvironment3. Ependymoma (EPN) is a paediatric brain tumour that relies on epigenomic remodelling to engender malignancy4,5; however, how these epigenetic mechanisms intersect with extrinsic neuronal signalling during EPN tumour progression is unknown. Here we show that the activity of serotonergic neurons regulates EPN tumorigenesis, and that serotonin itself also serves as an activating modification on histones. We found that inhibiting histone serotonylation blocks EPN tumorigenesis and regulates the expression of a core set of developmental transcription factors. High-throughput, in vivo screening of these transcription factors revealed that ETV5 promotes EPN tumorigenesis and functions by enhancing repressive chromatin states. Neuropeptide Y (NPY) is one of the genes repressed by ETV5, and its overexpression suppresses EPN tumour progression and tumour-associated network hyperactivity through synaptic remodelling. Collectively, this study identifies histone serotonylation as a key driver of EPN tumorigenesis, and also reveals how neuronal signalling, neuro-epigenomics and developmental programs are intertwined to drive malignancy in brain cancer.

Comparative Transcriptomic Analysis of Cerebellar Astrocytes across Developmental Stages and Brain Regions.

Astrocytes are the most abundant glial cell type in the central nervous system, and they play a crucial role in normal brain function. While gliogenesis and glial differentiation occur during perinatal cerebellar development, the processes that occur during early postnatal development remain obscure. In this study, we conducted transcriptomic profiling of postnatal cerebellar astrocytes at postnatal days 1, 7, 14, and 28 (P1, P7, P14, and P28), identifying temporal-specific gene signatures at each specific time point. Comparing these profiles with region-specific astrocyte differentially expressed genes (DEGs) published for the cortex, hippocampus, and olfactory bulb revealed cerebellar-specific gene signature across these developmental timepoints. Moreover, we conducted a comparative analysis of cerebellar astrocyte gene signatures with gene lists from pediatric brain tumors of cerebellar origin, including ependymoma and medulloblastoma. Notably, genes downregulated at P14, such as Kif11 and HMGB2, exhibited significant enrichment across all pediatric brain tumor groups, suggesting the importance of astrocytic gene repression during cerebellar development to these tumor subtypes. Collectively, our studies describe gene expression patterns during cerebellar astrocyte development, with potential implications for pediatric tumors originating in the cerebellum.

Remote neuronal activity drives glioma progression through SEMA4F.

The tumour microenvironment plays an essential role in malignancy, and neurons have emerged as a key component of the tumour microenvironment that promotes tumourigenesis across a host of cancers1,2. Recent studies on glioblastoma (GBM) highlight bidirectional signalling between tumours and neurons that propagates a vicious cycle of proliferation, synaptic integration and brain hyperactivity3-8; however, the identity of neuronal subtypes and tumour subpopulations driving this phenomenon is incompletely understood. Here we show that callosal projection neurons located in the hemisphere contralateral to primary GBM tumours promote progression and widespread infiltration. Using this platform to examine GBM infiltration, we identified an activity-dependent infiltrating population present at the leading edge of mouse and human tumours that is enriched for axon guidance genes. High-throughput, in vivo screening of these genes identified SEMA4F as a key regulator of tumourigenesis and activity-dependent progression. Furthermore, SEMA4F promotes the activity-dependent infiltrating population and propagates bidirectional signalling with neurons by remodelling tumour-adjacent synapses towards brain network hyperactivity. Collectively our studies demonstrate that subsets of neurons in locations remote to primary GBM promote malignant progression, and also show new mechanisms of glioma progression that are regulated by neuronal activity.

The genomic landscape of familial glioma.

Glioma is a rare brain tumor with a poor prognosis. Familial glioma is a subset of glioma with a strong genetic predisposition that accounts for approximately 5% of glioma cases. We performed whole-genome sequencing on an exploratory cohort of 203 individuals from 189 families with a history of familial glioma and an additional validation cohort of 122 individuals from 115 families. We found significant enrichment of rare deleterious variants of seven genes in both cohorts, and the most significantly enriched gene was HERC2 (P = 0.0006). Furthermore, we identified rare noncoding variants in both cohorts that were predicted to affect transcription factor binding sites or cause cryptic splicing. Last, we selected a subset of discovered genes for validation by CRISPR knockdown screening and found that DMBT1, HP1BP3, and ZCH7B3 have profound impacts on proliferation. This study performs comprehensive surveillance of the genomic landscape of familial glioma.

Remote neuronal activity drives glioma infiltration via Sema4f.

The tumor microenvironment (TME) plays an essential role in malignancy and neurons have emerged as a key component of the TME that promotes tumorigenesis across a host of cancers. Recent studies on glioblastoma (GBM) highlight bi-directional signaling between tumors and neurons that propagates a vicious cycle of proliferation, synaptic integration, and brain hyperactivity; however, the identity of neuronal subtypes and tumor subpopulations driving this phenomenon are incompletely understood. Here we show that callosal projection neurons located in the hemisphere contralateral to primary GBM tumors promote progression and widespread infiltration. Using this platform to examine GBM infiltration, we identified an activity dependent infiltrating population present at the leading edge of mouse and human tumors that is enriched for axon guidance genes. High-throughput, in vivo screening of these genes identified Sema4F as a key regulator of tumorigenesis and activity-dependent infiltration. Furthermore, Sema4F promotes the activity-dependent infiltrating population and propagates bi-directional signaling with neurons by remodeling tumor adjacent synapses towards brain network hyperactivity. Collectively, our studies demonstrate that subsets of neurons in locations remote to primary GBM promote malignant progression, while revealing new mechanisms of tumor infiltration that are regulated by neuronal activity.

The current status and outcomes of in-hospital P2Y12 receptor inhibitor switching in Korean patients with acute myocardial infarction.

BACKGROUND/AIMS: While switching strategies of P2Y12 receptor inhibitors (RIs) have sometimes been used in acute myocardial infarction (AMI) patients, the current status of in-hospital P2Y12RI switching remains unknown. METHODS: Overall, 8,476 AMI patients who underwent successful revascularization from Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH) were divided according to in-hospital P2Y12RI strategies, and net adverse cardiovascular events (NACEs), defined as a composite of cardiac death, non-fatal myocardial infarction (MI), stroke, or thrombolysis in myocardial infarction (TIMI) major bleeding during hospitalization were compared. RESULTS: Patients with in-hospital P2Y12RI switching accounted for 16.5%, of which 867 patients were switched from clopidogrel to potent P2Y12RI (C-P) and 532 patients from potent P2Y12RI to clopidogrel (P-C). There were no differences in NACEs among the unchanged clopidogrel, the unchanged potent P2Y12RIs, and the P2Y12RI switching groups. However, compared to the unchanged clopidogrel group, the C-P group had a higher incidence of non-fatal MI, and the P-C group had a higher incidence of TIMI major bleeding. In clinical events of in-hospital P2Y12RI switching, 90.9% of non-fatal MI occurred during pre-switching clopidogrel administration, 60.7% of TIMI major bleeding was related to pre-switching P2Y12RIs, and 71.4% of TIMI major bleeding was related to potent P2Y12RIs. Only 21.6% of the P2Y12RI switching group switched to P2Y12RIs after a loading dose (LD); however, there were no differences in clinical events between patients with and without LD. CONCLUSION: In-hospital P2Y12RI switching occurred occasionally, but had relatively similar clinical outcomes compared to unchanged P2Y12RIs in Korean AMI patients. Non-fatal MI and bleeding appeared to be mainly related to pre-switching P2Y12RIs.

A Parkinson's disease gene, DJ-1, regulates anti-inflammatory roles of astrocytes through prostaglandin D2 synthase expression.

Dysfunctional regulation of inflammation may contribute to the progression of neurodegenerative diseases. The results of this study revealed that DJ-1, a Parkinson's disease (PD) gene, regulated expression of prostaglandin D2 synthase (PTGDS) and production of prostaglandin D2 (PGD2), by which DJ-1 enhanced anti-inflammatory function of astrocytes. In injured DJ-1 knockout (KO) brain, expression of tumor necrosis factor-alpha (TNF-α) was more increased, but that of anti-inflammatory heme oxygenase-1 (HO-1) was less increased compared with that in injured wild-type (WT) brain. Similarly, astrocyte-conditioned media (ACM) prepared from DJ-1-KO astrocytes less induced HO-1 expression and less inhibited expression of inflammatory mediators in microglia. With respect to the underlying mechanism, we found that PTGDS that induced expression of HO-1 was lower in DJ-1 KO astrocytes and brains compared with their WT counterparts. In addition, PTGDS levels increased in the injured brain of WT mice, but barely in that of KO mice. We also found that DJ-1 regulated PTGDS expression through Sox9. Thus, Sox9 siRNAs reduced PTGDS expression in WT astrocytes, and Sox9 overexpression rescued PTGDS expression in DJ-1 KO astrocytes. In agreement with these results, ACM from Sox9 siRNA-treated astrocytes and that from Sox9-overexpression astrocytes exerted opposite effects on HO-1 expression and anti-inflammation. These findings suggest that DJ-1 positively regulates anti-inflammatory functions of astrocytes, and that DJ-1 dysfunction contributes to the excessive inflammatory response in PD development.

Comparison of short-term clinical outcomes between ticagrelor versus clopidogrel in patients with acute myocardial infarction undergoing successful revascularization; from Korea Acute Myocardial Infarction Registry-National Institute of Health.

BACKGROUND: Although ticagrelor has been well-known to improve clinical outcomes in patients with acute myocardial infarction (AMI) without increased bleeding risk, its clinical impacts have not been well established in East Asian patients. METHODS: Between November 2011 and June 2015, a total of 8010 patients (1377 patients were prescribed ticagrelor and 6633 patients clopidogrel) undergoing successful revascularization were analyzed from Korea Acute Myocardial Infarction Registry-National Institute of Health. The patients who discontinued or occurred in-hospital switching between two antiplatelet agents were excluded. RESULTS: After propensity score matching (1377 pairs), no difference in the composite of cardiac death, MI, stroke, or target vessel revascularization at 6months was observed between two groups (4.2% vs. 4.9%, p=0.499). However, the incidences of in-hospital Thrombolysis In Myocardial Infarction (TIMI) major and minor bleeding were higher in ticagrelor than clopidogrel (2.6% vs. 1.2%, p=0.008; 3.8% vs. 2.5%, p=0.051). The in-hospital mortality was higher in patients with than those without TIMI major bleeding (11.3% vs. 0.9%, p<0.001). In a subgroup analysis, a higher risk for in-hospital TIMI major bleeding with ticagrelor was observed in patients≥75years or with body weight<60kg (odd ratio [OR]=3.209; 95% confidence interval [CI]=1.356-7.592) and in those received trans-femoral intervention (OR=1.996; 95% CI=1.061-3.754). CONCLUSIONS: Our study shows that ticagrelor did not reduce ischemic events yet, however, was associated with increased risk of bleeding complications compared with clopidogrel. Further large-scale, long-term, randomized trials should be required to assess the outcomes of ticagrelor for East Asian patients with AMI.

DJ-1 facilitates the interaction between STAT1 and its phosphatase, SHP-1, in brain microglia and astrocytes: A novel anti-inflammatory function of DJ-1.

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder caused by the death of dopaminergic neurons in the substantia nigra. Importantly, altered astrocyte and microglial functions could contribute to neuronal death in PD. In this study, we demonstrate a novel mechanism by which DJ-1 (PARK7), an early onset autosomal-recessive PD gene, negatively regulates inflammatory responses of astrocytes and microglia by facilitating the interaction between STAT1 and its phosphatase, SHP-1 (Src-homology 2-domain containing protein tyrosine phosphatase-1). Astrocytes and microglia cultured from DJ-1-knockout (KO) mice exhibited increased expression of inflammatory mediators and phosphorylation levels of STAT1 (p-STAT1) in response to interferon-gamma (IFN-γ) compared to cells from wild-type (WT) mice. DJ-1 deficiency also attenuated IFN-γ-induced interactions of SHP-1 with p-STAT1 and STAT1, measured 1 and 12h after IFN-γ treatment, respectively. Subsequent experiments showed that DJ-1 directly interacts with SHP-1, p-STAT1, and STAT1. Notably, DJ-1 bound to SHP-1 independently of IFN-γ, whereas the interactions of DJ-1 with p-STAT1 and STAT1 were dependent on IFN-γ. Similar results were obtained in brain slice cultures, where IFN-γ induced much stronger STAT1 phosphorylation and inflammatory responses in KO slices than in WT slices. Moreover, IFN-γ treatment induced neuronal damage in KO slices. Collectively, these findings suggest that DJ-1 may function as a scaffold protein that facilitates SHP-1 interactions with p-STAT1 and STAT1, thereby preventing extensive and prolonged STAT1 activation. Thus, the loss of DJ-1 function may increase the risk of PD by enhancing brain inflammation.

Impaired inflammatory responses in murine Lrrk2-knockdown brain microglia.

LRRK2, a Parkinson's disease associated gene, is highly expressed in microglia in addition to neurons; however, its function in microglia has not been evaluated. Using Lrrk2 knockdown (Lrrk2-KD) murine microglia prepared by lentiviral-mediated transfer of Lrrk2-specific small inhibitory hairpin RNA (shRNA), we found that Lrrk2 deficiency attenuated lipopolysaccharide (LPS)-induced mRNA and/or protein expression of inducible nitric oxide synthase, TNF-α, IL-1ß and IL-6. LPS-induced phosphorylation of p38 mitogen-activated protein kinase and stimulation of NF-κB-responsive luciferase reporter activity was also decreased in Lrrk2-KD cells. Interestingly, the decrease in NF-κB transcriptional activity measured by luciferase assays appeared to reflect increased binding of the inhibitory NF-κB homodimer, p50/p50, to DNA. In LPS-responsive HEK293T cells, overexpression of the human LRRK2 pathologic, kinase-active mutant G2019S increased basal and LPS-induced levels of phosphorylated p38 and JNK, whereas wild-type and other pathologic (R1441C and G2385R) or artificial kinase-dead (D1994A) LRRK2 mutants either enhanced or did not change basal and LPS-induced p38 and JNK phosphorylation levels. However, wild-type LRRK2 and all LRRK2 mutant variants equally enhanced NF-κB transcriptional activity. Taken together, these results suggest that LRRK2 is a positive regulator of inflammation in murine microglia, and LRRK2 mutations may alter the microenvironment of the brain to favor neuroinflammation.

The absence of coronary artery calcification does not rule out the presence of significant coronary artery disease in Asian patients with acute chest pain.

The absence of coronary artery calcification (CAC) has been used to as an indication to rule out significant coronary artery disease (CAD). However, diagnostic usefulness of 'zero calcium score criteria' as a decision-making strategy to rule out significant CAD as the etiology of acute chest pain has not been studied in depth, especially in Asian ethnicity. We prospectively enrolled 136 Korean patients (58% men, 56 ± 13 years) who presented to the emergency department (ED) with acute chest pain and non-diagnostic ECG. All patients underwent 64-slice CT for calcium scoring and coronary CT angiography (cCTA). We investigated the association of CAC with the presence of ≥50% CAD on cCTA and with a final diagnosis of an acute coronary syndrome (ACS). Ninety-two patients out of 136 (68%) did not show detectable CAC, and 14 out of these 92 without CAC (15%) had ≥50% CAD on cCTA. Sensitivity, specificity, positive predictive value and negative predictive value of zero calcium score criteria for the detection of ≥50% CAD were 0.66 (95% confidence interval, 0.50-0.80), 0.83 (0.74-0.90), 0.64 (0.48-0.77), 0.85 (0.75-0.91), respectively. Patients who had ≥50% CAD without detectable CAC were younger (P = 0.001), and had a higher prevalence of smoking (P = 0.048) as compared to patients with a degree of CAC. Most of the patients with ≥50% CAD of non-calcified plaque were younger than 60 years of age (79%, 11/14), however, 3 of them were older than 60 years of age. Forty-five patients (33%) were subsequently diagnosed as having ACS, and 38% (17/45) of them had no CAC. Zero calcium score did not necessarily guarantee the absence of significant CAD, even in patients older than 60 years, in Asian ethnicity presenting to the ED with chest pain.

Variation in atherosclerotic plaque composition according to increasing coronary artery calcium scores on computed tomography angiography.

Increasing coronary artery calcium scores (CACS) are independently associated with cardiac events. Recent advents in coronary computed tomography angiography (CCTA) have allowed us to better characterize individual plaque. Currently, it is unknown if higher CACS are likely to be associated with more calcified or mixed and heterogeneous plaque burden on CCTA. The study population consisted of 1,043 South Korean asymptomatic subjects (49 ± 10 years, 62% men) who underwent CCTA (64-slice MDCT). Plaques were classified on contrast-enhanced CCTA as non-calcified, mixed, and calcified on a per-segment basis according to the modified American Heart Association classification. The majority of the study participants had no coronary calcification (n = 866, 83%), whereas CACS> 0 was observed in 177 participants (17%). Only 40 (5%) participants in absence of CACS had exclusively non-calcified plaque, whereas 10 (1.2%) had significant coronary artery disease. With increasing CACS, study participants were more likely to have exclusively mixed or combination atherosclerotic plaques (P = 0.001). Among individuals with CACS 1-10, the prevalence of at least two coronary segments with mixed plaques was 4%, increasing up to 18 and 41% with CACS of 11-100 and >100. The respective prevalence of ≥2 coronary segments (calcified plaques) with increasing CACS were 6%, 16 and 26% (P = 0.01) and of non-calcified plaques were 6%, 6 and 11% (P = 0.71). In multivariable adjusted analyses, those with CACS >100 were 7.17 times (95% CI: 1.36-37.68) more likely to have ≥2 coronary segments with calcified plaque comparing with CACS 1-10. On the other hand the respective risk was higher for presence of ≥2 segments with mixed plaques (odds ratio: 15.81, 95% CI: 3.14-79.58). Absence of CAC is associated with a negligible presence of any atherosclerotic disease as detected by CCTA in asymptomatic population. A higher CACS is more likely to be associated with heterogeneous coronary plaque (combination of calcified, non-calcified, and mixed plaques), and appears to be more strongly associated with a higher burden of mixed plaque.

Coronary computed tomography angiography as a screening tool for the detection of occult coronary artery disease in asymptomatic individuals.

OBJECTIVES: The purpose of this study was to evaluate the prevalence of occult coronary artery disease (CAD) with coronary computed tomography angiography (CTA) to characterize plaque composition and to evaluate the potential of this new technology to impact risk stratification in asymptomatic middle-aged subjects. BACKGROUND: There is a paucity of information regarding the role of CTA for the detection of occult CAD in asymptomatic individuals. METHODS: We consecutively enrolled 1,000 middle-aged asymptomatic subjects (age 50 +/- 9 years, 63% men) who underwent CTA (64-slice multidetector row computed tomography) as part of a general health evaluation. RESULTS: Atherosclerotic plaques were identified in 215 (22%, 2 +/- 1 segments/subject) individuals; 40 individuals (4%) had only noncalcified plaques. Fifty-two (5%) subjects had significant (>or=50%) diameter stenosis and 21 (2%) had severe (>or=75%) stenosis. Thirteen (25%) and 30 (58%) subjects with significant stenosis were classified into National Cholesterol Education Program low-risk and mild coronary calcification (coronary artery calcium scores <100), respectively. Midterm follow-up (17 +/- 2 months) revealed 15 cardiac events only in those with CAD on CTA: 1 unstable angina requiring hospital stay and 14 revascularization procedures. Most (87%) events occurred within 90 days of index CTA. CONCLUSIONS: The prevalence of occult CAD in apparently healthy individuals was not negligible, although their midterm prognosis was good. CTA has a potential to provide a better insight about the occult CAD in this population. However, on the basis of our results and considering present radiation exposure data, we cannot recommend that CTA be used as a screening tool for this population at this point.

Stent-related cardiac events after non-cardiac surgery: drug-eluting stent vs. bare metal stent.

For evaluation of post-operative stent associated cardiac events after drug-eluting stent (DES) implantation we analyzed data of 138 patients who underwent non-cardiac surgery after DES implantation and compared the data with those of 101 patients who underwent non-cardiac surgery after bare metal stent (BMS) implantation. Three patients (2.2%) in DES group developed post-operative cardiac events and none in BMS group (p=0.2). One patient died due to suspected stent thrombosis and the other two had myocardial infarction due to angiographically proven stent thrombosis. The time interval between stent implantation and surgery in those with cardiac events was 6, 264, and 367 days, respectively. Our data shows that peri-operative stent-related thrombotic complications can occur long after DES implantation and careful peri-operative monitoring for cardiac events is needed in patients receiving non-cardiac surgery after DES implantation.

NF-kappaB decoy potentiates the effects of radiation on vascular smooth muscle cells by enhancing apoptosis.

NF-kappaB promotes cell survival against external stress such as radiation. We examined whether NF-kappaB decoy transfection enhances the antiproliferative effects of radiation on vascular smooth muscle cells (VSMCs) in vitro. The irradiation induced activation or nuclear translocation of NF-kappaB p65 in VSMCs was confirmed by immunofluorescence. NF-kappaB decoy transfection resulted in inhibition of the radiation-induced NF-kappaB activation in VSMCs and the subsequent reduction of transcription and translocation of ICAM, iNOS, and TNF-alpha, downstream molecules under the control of NF-kappaB. By using MTT assay, NF-kappaB decoy augmented the antiproliferative effects of radiation, where the effect of low dose radiation (2 and 8-Gy) of the cells transfected with NF-kappaB decoy was equivalent to the high dose (16-Gy) irradiated non-transfected cells at 48 h after irradiation: 1.06+/-0.16, 1.11+/-0.22, 1.20+/-0.25, respectively. The decrease in proliferation and survival of the radiation treated cells by flow cytometry analysis showed that NF-kappaB inhibition did not show any additive effects on the cell cycle of the irradiated VSMCs, while apoptosis was significantly increased after NF-kappaB decoy transfection in the irradiated VSMCs (apoptosis fraction: 13.33+/-2.08% vs. 26.29+/-7.43%, for radiation only vs. radiation+NF-kappaB decoy transfection, P < 0.05). In addition, at 48 h, NF-kappaB decoy transfection dose dependently (10 microM vs. 20 microM) inhibited proliferation of 16Gy-irradiated VSMCs, and showed greater antiproliferative efficacy than 100 microM sulfasalazine, a specific NF-kappaB inhibitor. These results indicate that NF-kappaB inhibition reduces proliferation and survival of irradiated VSMCs, likely by increased apoptosis rather than additive cell cycle arrest and suggest the possibility of adjunctive gene therapy using NF-kappaB decoy to improve efficacy and to decrease the adverse effects of intracoronary radiation therapy.

Thalidomide as a potent inhibitor of neointimal hyperplasia after balloon injury in rat carotid artery.

OBJECTIVE: Inflammation is one of the main pathogeneses of neointimal hyperplasia after coronary intervention. Thalidomide, because of its potent antiinflammatory and immunomodulatory properties, is being re-evaluated in several clinical fields. Therefore, we examined whether thalidomide therapy affects neointimal formation. METHODS AND RESULTS: In male Sprague-Dawley rats, 100 mg/kg of either thalidomide or sucrose (control) was administered daily from 3 days before injury to 2 weeks after conventional carotid artery denudation injury. Thalidomide administration resulted in a significant reduction of neointimal formation (neointima to media ratio 1.26+/-0.29 versus 0.35+/-0.13, P<0.001) and proliferative activity of vascular smooth muscle cells. In addition, arterial macrophage infiltration and local expressions of tumor necrosis factor alpha (TNF-alpha) and basic fibroblast growth factor (bFGF) in the injured arteries as measured by immunohistochemistry and immunoblot analysis were significantly reduced by thalidomide treatment. Serum TNF-alpha, measured by ELISA, was also significantly reduced in the thalidomide-treated animals compared with controls after injury (856+/-213 versus 449+/-68 pg/mL on day 3, P=0.001; 129+/-34 versus 63+/-18 pg/mL on day 14, P=0.001), and we observed a good positive correlation between the serum TNF-alpha levels and the severity of neointimal growth. CONCLUSIONS: We found that thalidomide, through its antiinflammatory and antiproliferative effects, significantly inhibits neointimal hyperplasia in balloon-injured rat carotid arteries. Our results suggest a potential role of thalidomide as a potent inhibitor of neointimal formation after angioplasty.