Summary Cerebral cavernous malformations (CCMs) are vascular disorders that affect up to 0.5% of the total population. About 20% of CCMs are inherited because of familial mutations in CCM genes, including CCM1 / KRIT1 , CCM2 / MGC4607 , and CCM3 / PDCD10 , whereas the etiology of a majority of simplex CCM-affected individuals remains unclear. Here, we report somatic mutations of MAP3K3 , PIK3CA , MAP2K7 , and CCM genes in CCM lesions. In particular, somatic hotspot mutations of PIK3CA are found in 11 of 38 individuals with CCMs, and a MAP3K3 somatic mutation (c.1323C>G [p.Ile441Met]) is detected in 37.0% (34 of 92) of the simplex CCM-affected individuals. Strikingly, the MAP3K3 c.1323C>G mutation presents in 95.7% (22 of 23) of the popcorn-like lesions but only 2.5% (1 of 40) of the subacute-bleeding or multifocal lesions that are predominantly attributed to mutations in the CCM1/2/3 signaling complex. Leveraging mini-bulk sequencing, we demonstrate the enrichment of MAP3K3 c.1323C>G mutation in CCM endothelium. Mechanistically, beyond the activation of CCM1/2/3-inhibited ERK5 signaling, MEKK3 p.Ile441Met ( MAP3K3 encodes MEKK3) also activates ERK1/2, JNK, and p38 pathways because of mutation-induced MEKK3 kinase activity enhancement. Collectively, we identified several somatic activating mutations in CCM endothelium, and the MAP3K3 c.1323C>G mutation defines a primary CCM subtype with distinct characteristics in signaling activation and magnetic resonance imaging appearance.

Rationale: Brain arteriovenous malformations (bAVMs) are abnormal entanglement of blood vessels in brain, with direct connections from arteries to veins, lacking functional capillary bed. Although several somatic mutations were reported, the molecular mechanism and genetic disposition of bAVM remain poorly understood. Objective: We aim to identify transcriptional anomalies and critical functional pathways in bAVM lesions, and explore their association with key de novo germline and somatic variants in bAVM patients. Methods and Results: We established a comprehensive bAVM dataset from 269 patients, by performing single-cell sequencing of 17 bAVM lesions, whole-exome sequencing of germline DNA from 60 case-unaffected-parental trios, and genomic/transcriptomic sequencing of 231 bAVM lesions. We found abnormal expression of endothelial and mesenchymal markers in bAVM at both bulk and single-cell level, which was validated by flow-cytometric analysis and immunofluorescence staining, suggesting an involvement of Endothelial-to-Mesenchymal transition (EndMT) process in AVM. Using data from the 60 trios we identified non-synonymous de novo germline mutations (DNMs) affecting 46 genes, including EXPH5 (detected in two independent cases), and vessel-related genes such as EPAS1 and ENG. Interestingly, knockdown of epas1 in zebrafish embryo showed AVM-like phenotype exclusively in brain. Subsequent computational and experimental analyses demonstrated that expression of genes affected by DNMs was enriched in vascular cell types and was involved in EndMT-relevant behaviours including cell migration, angiogenesis and cell-marker transition. Moreover, we detected somatic KRAS mutations in 129 of 179 (72%) cases, and showed that KRAS mutations were associated with bleeding as the first symptom (p=0.0072). Following experimental studies demonstrated that KRAS mutations independently regulated EndMT features, consolidating the involvement of EndMT in this disease. Lastly, we showed that Lovastatin reversed EndMT features in vitro and ex vivo. Conclusions: Our results suggest the convergent role of DNMs and somatic mutations in regulating EndMT in bAVM and provided a potential therapeutic option.

OBJECTIVEIntracranial giant cell tumors (GCTs) are extremely rare neoplasms with dismal survival and recurrence rates. The authors aimed to confirm independent adverse factors for progression-free survival (PFS) and to propose an optimal treatment algorithm.METHODSThe authors reviewed the clinical data of 43 cases of intracranial GCTs in their series. They also reviewed 90 cases of previously reported GCTs in the English language between 1982 and 2017 using Ovid MEDLINE, Embase, PubMed, and Cochrane databases with keywords of “giant cell tumor” or “osteoclastoma” and “skull,” “skull base,” “temporal,” “frontal,” “sphenoid,” or “occipital.” These prior publication data were processed and used according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Aforementioned risk factors for the authors’ series and the pooled cases were evaluated in patients not lost to follow-up (m = 38 and n = 128, respectively).RESULTSThe authors’ cohort included 28 males and 15 females with a mean age of 30.5 years. Gross-total resection (GTR) was achieved in 15 (34.9%) patients. Fifteen patients (39.5%) who did not undergo GTR received postoperative radiotherapy with a mean total dose of 54.7 ± 4.1 Gy. After a mean follow-up of 71.3 months, 12 (31.6%) patients experienced recurrence, and 4 (10.5%) died of disease. The actuarial 5-year PFS and overall survival (OS) were 68.6% and 90.0% in the authors’ cohort, respectively. A multivariate Cox regression analysis verified that partial resection (HR 7.909, 95% CI 2.296–27.247, p = 0.001), no radiotherapy (HR 0.114, 95% CI 0.023–0.568, p = 0.008), and Ki-67 ≥ 10% (HR 7.816, 95% CI 1.584–38.575, p = 0.012) were independent adverse factors for PFS. Among the 90 cases in the literature, GTR was achieved in 49 (54.4%) cases. Radiotherapy was administered to 33 (36.7%) patients with a mean total dose of 47.1 ± 5.6 Gy. After a mean follow-up of 31.5 months, recurrence and death occurred in 17 (18.9%) and 5 (5.6%) cases, respectively. Among the pooled cases, the 5-year PFS and OS were 69.6% and 89.2%, respectively. A multivariate model demonstrated that partial resection (HR 4.792, 95% CI 2.909–7.893, p < 0.001) and no radiotherapy (HR 0.165, 95% CI 0.065–0.423, p < 0.001) were independent adverse factors for poor PFS.CONCLUSIONSGTR and radiotherapy were independent favorable factors for PFS of intracranial GCTs. Based on these findings, GTR alone or GTR plus radiotherapy was advocated as an optimal treatment; otherwise, partial resection plus radiotherapy with a dose ≥ 45 Gy, if tolerable, was a secondary alternative. Lack of randomized data of the study was stressed, and future studies with larger cohorts are necessary to verify these findings.Systematic review no.: CRD42018090878 (crd.york.ac.uk/PROSPERO/)

Background and Purpose: In unruptured brain arteriovenous malformations (bAVMs), microhemorrhage portends a higher risk of future rupture and may represent a transitional state along the continuum of destabilization. Exploration of the molecular and cellular mechanisms of microhemorrhage will provide a possible target for medical treatment to prevent bAVM bleeding. Methods: We performed RNA sequencing analysis on 34 unruptured bAVM surgical samples. Functional pathway analysis was performed to identify potential signals associated with the microhemorrhagic phenotype. Candidate gene was then investigated in bAVM specimens by immunohistochemical staining. Several functional assays were used to investigate the effects of candidate genes on the phenotypic properties of cultured human umbilical vein endothelial cells. Then, Masson trichrome staining and immunofluorescence staining were used to evaluate the phenotypic and molecular changes in bAVM tissue. Results: Via RNA sequencing, we identified differential gene expression between 18 microhemorrhagic bAVMs and 16 nonmicrohemorrhagic bAVMs. TGFβ (transforming growth factor-beta)/BMP (bone morphogenetic protein) signaling was associated with the bAVM microhemorrhage group when SMAD6 (SMAD family member 6) was downregulated. Immunohistochemical staining showed that the vascular endothelium of microhemorrhagic bAVMs exhibited decreased SMAD6 expression. Functional assays revealed that SMAD6 downregulation promoted the formation of endothelial cell tubes with deficient cell-cell junctions and facilitated the acquisition of mesenchymal behavior by endothelial cells. Masson trichrome and immunofluorescence staining demonstrated that mesenchymal phenotype of endothelial cells is promoted in microhemorrhagic bAVMs. Conclusions: TGFβ/BMP signaling mediated by SMAD6 in vascular endothelial cells is associated with microhemorrhagic bAVMs, and mesenchymal behavior of endothelial cells induced by SMAD6 downregulation is related with bAVM microhemorrhage.

The tumor immune microenvironment (TIME) plays a pivotal role in tumor development, progression, and prognosis. However, the characteristics of the TIME in diffuse astrocytoma (DA) are still unclear. Leveraging mass cytometry with a panel of 33 markers, we analyzed the infiltrating immune cells from 10 DA and 4 oligodendroglioma (OG) tissues and provided a single cell-resolution landscape of the intricate immune microenvironment. Our study profiled the composition of the TIME in DA and confirmed the presence of immune cells, such as glioma-associated microglia/macrophages (GAMs), CD8+ T cells, CD4+ T cells, regulatory T cells (Tregs), and natural killer cells. Increased percentages of PD-1+ CD8+ T cells, TIM-3+ CD4+ T cell subpopulations, Tregs and pro-tumor phenotype GAMs substantially contribute to the local immunosuppressive microenvironment in DA. DAs and OGs share similar compositions in terms of immune cells, while GAMs in DA exhibit more inhibitory characteristics than those in OG.

OBJECTIVEThe overall survival and pertinent adverse factors for primary intracranial malignant melanoma (PIMM) have not been previously determined. This aim of this study was to determine the rates of progression-free survival (PFS) and overall survival (OS) and identify the adverse factors for PIMM.METHODSThis study included 15 cases from the authors’ own series and 100 cases with detailed clinical data that were obtained from the literature from 1914 to 2018 using the Ovid Medline, EMBASE, PubMed, Cochrane, and EBSCO databases. Patient demographics, treatment (surgery, chemotherapy, and radiotherapy [RT]), PFS, and OS were reviewed. Data from prior publications were processed and used according to PRISMA guidelines.RESULTSDiffuse lesions were identified in 24 (20.9%) patients, who had a younger age (p < 0.001). The mean follow-up time was 16.6 months, and 76 (66.1%) deaths occurred. The 6-month, 1-year, 3-year, and 5-year OS rates of the whole cohort were 62.8%, 49.9%, 28.9%, and 17.2%, respectively, with an estimated median survival time (EMST) of 12.0 months. The multivariate analysis revealed that gross-total resection (GTR) (HR 0.299, 95% CI 0.180–0.497, p < 0.001), radiotherapy (HR 0.577, 95% CI 0.359–0.929, p = 0.024), and chemotherapy (HR 0.420, 95% CI 0.240–0.735, p = 0.002) predicted a better OS. The EMST was 5.0 months in patients with diffuse-type PIMM and 13.0 months in patients with the solitary type. Patients receiving GTR with adjuvant RT and/or chemotherapy (GTR + [RT and/or chemo]) had significantly higher 1-year and 5-year OS rates (73.0% and 40.1%, respectively) and a longer EMST (53 months) than patients who underwent GTR alone (20.5 months) or RT and/or chemotherapy without GTR (13.0 months).CONCLUSIONSOptimal outcomes could be achieved by radical resection plus postoperative radiotherapy and/or chemotherapy. Patients with diffuse PIMM have a more severe clinical spectrum and poorer survival than patients with solitary PIMM. Immunotherapy and targeted therapy show promise as treatment options for PIMM based on results in patients with brain metastases from extracranial melanoma.

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BACKGROUND. Lower-grade gliomas (LGGs) vary widely in terms of the patient's overall survival (OS). There is no current, valid method that could exactly predict the survival. The effects of intratumoral immune infiltration on clinical outcome have been widely reported. Thus, we aim to develop an immune infiltration signature to predict the survival of LGG patients. METHODS. We analyzed 1216 LGGs from 5 public data sets, including 2 RNA sequencing data sets and 3 microarray data sets. Least absolute shrinkage and selection operator (LASSO) Cox regression was used to select an immune infiltration signature and build a risk score. The performance of the risk score was assessed in the training set (329 patients), internal validation set (140 patients), and 4 external validation sets (405, 118, 88, and 136 patients). RESULTS. An immune infiltration signature consisting of 20 immune metagenes was used to generate a risk score. The performance of the risk score was thoroughly verified in the training and validation sets. Additionally, we found that the risk score was positively correlated with the expression levels of TGF-β and PD-L1, which were important targets of combination immunotherapy. Furthermore, a nomogram incorporating the risk score, patient's age, and tumor grade was developed to predict the OS, and it performed well in all the training and validation sets (C-index: 0.873, 0.881, 0.781, 0.765, 0.721, and 0.753). CONCLUSION. The risk score based on the immune infiltration signature has reliable prognostic and predictive value for patients with LGGs and is a potential biomarker for the cotargeting immunotherapy.