Role of Merlin/NF2 inactivation in tumor biology

Lumbar spinal intraosseous schwannoma: a non-operative approach

Intraosseous schwannomas are benign tumours composed of nerve sheath cells, most commonly affecting the mandible and sacrum. Such intraosseous schwannomas in the vertebra can result in spinal instability causing deformity, pain and even neurological compression. Vertebral involvement in the lumbar spine is extremely rare. A case of a schwannoma of the lumbar spine at the level of L3/L4 is presented. It resulted in progressive lower back pain and right lower limb radiculopathy. The clinical findings, radiological reports and histological diagnosis of this case, along with a review of the literature, are presented. The rationale for non-surgical management of this rare benign tumour is also explored.

Clinical Management of Supratentorial Non-Skull Base Meningiomas

Supratentorial non-skull base meningiomas are the most common primary central nervous system tumor subtype. An understanding of their pathophysiology, imaging characteristics, and clinical management options will prove of substantial value to the multi-disciplinary team which may be involved in their care. Extensive review of the broad literature on the topic is conducted. Narrowing the scope to meningiomas located in the supratentorial non-skull base anatomic location highlights nuances specific to this tumor subtype. Advances in our understanding of the natural history of the disease and how findings from both molecular pathology and neuroimaging have impacted our understanding are discussed. Clinical management and the rationale underlying specific approaches including observation, surgery, radiation, and investigational systemic therapies is covered in detail. Future directions for probable advances in the near and intermediate term are reviewed.

Structure-based discovery of a novel small-molecule inhibitor of TEAD palmitoylation with anticancer activity

The paralogous oncogenic transcriptional coactivators YAP and TAZ are the distal effectors of the Hippo signaling pathway, which plays a critical role in cell proliferation, survival and cell fate specification. They are frequently deregulated in most human cancers, where they contribute to multiple aspects of tumorigenesis including growth, metabolism, metastasis and chemo/immunotherapy resistance. Thus, they provide a critical point for therapeutic intervention. However, due to their intrinsically disordered structure, they are challenging to target directly. Since YAP/TAZ exerts oncogenic activity by associating with the TEAD1-4 transcription factors, to regulate target gene expression, YAP activity can be controlled indirectly by regulating TEAD1-4. Interestingly, TEADs undergo autopalmitoylation, which is essential for their stability and function, and small-molecule inhibitors that prevent this posttranslational modification can render them unstable. In this article we report discovery of a novel small molecule inhibitor of YAP activity. We combined structure-based virtual ligand screening with biochemical and cell biological studies and identified JM7, which inhibits YAP transcriptional reporter activity with an IC50 of 972 nMoles/Ltr. Further, it inhibits YAP target gene expression, without affecting YAP/TEAD localization. Mechanistically, JM7 inhibits TEAD palmitoylation and renders them unstable. Cellular thermal shift assay revealed that JM7 directly binds to TEAD1-4 in cells. Consistent with the inhibitory effect of JM7 on YAP activity, it significantly impairs proliferation, colony-formation and migration of mesothelioma (NCI-H226), breast (MDA-MB-231) and ovarian (OVCAR-8) cancer cells that exhibit increased YAP activity. Collectively, these results establish JM7 as a novel lead compound for development of more potent inhibitors of TEAD palmitoylation for treating cancer.

The critical role of the Hippo signaling pathway in kidney diseases

The Hippo signaling pathway is involved in cell growth, proliferation, and apoptosis, and it plays a key role in regulating organ size, tissue regeneration, and tumor development. The Hippo signaling pathway also participates in the occurrence and development of various human diseases. Recently, many studies have shown that the Hippo pathway is closely related to renal diseases, including renal cancer, cystic kidney disease, diabetic nephropathy, and renal fibrosis, and it promotes the transformation of acute kidney disease to chronic kidney disease (CKD). The present paper summarizes and analyzes the research status of the Hippo signaling pathway in different kidney diseases, and it also summarizes the expression of Hippo signaling pathway components in pathological tissues of kidney diseases. In addition, the present paper discusses the positive therapeutic significance of traditional Chinese medicine (TCM) in regulating the Hippo signaling pathway for treating kidney diseases. This article introduces new targets and ideas for drug development, clinical diagnosis, and treatment of kidney diseases.

Multiple craniospinal tumors in a pediatric patient with neurofibromatosis type 2: a case report

INTRODUCTION

Neurofibromatosis type 2 (NF-2) is an inherited disease, linked with abnormalities in the NF-2 gene, which is located on chromosome 22 and involved in merlin production. Many craniospinal tumors are common in individuals with NF-2. We present a case of NF-2 with the rapid symptomatic progression of multiple craniospinal tumors.

CASE REPORT

A 12-year-old male complained of headache and hearing impairment in the right ear for 7 months. Brain magnetic resonance imaging (MRI) revealed a right frontal meningioma, bilateral vestibular and trigeminal schwannomas, and a brainstem tumor. He was diagnosed with NF-2 and underwent brain surgery and radiotherapy for chordoid meningioma. He complained of right leg motor weakness 5 months post-surgery. The spine MRI showed multiple heterogeneously enhanced masses spreading over the entire spinal cord. The symptomatic intradural extramedullary mass at the cervicothoracic area was removed and the histological finding was schwannoma. His leg motor weakness was relieved after surgery. At the 6-month follow-up, brain MRI revealed the progression of the vestibular schwannoma, trigeminal schwannoma, and brainstem tumor. The patient was treated with bevacizumab (5 mg/kg) every 2 weeks for 6 months. For 2 years, all of the craniospinal tumors were stable without neurological deterioration after the completion of chemotherapy.

CONCLUSION

Meningiomas and schwannomas grow slowly in most patients with NF-2, but these multiple craniospinal tumors can show sudden rapid growth and manifest as neurological symptoms in a pediatric patient. These tumors could be controlled with local symptomatic and systemic bevacizumab treatments.

A mechanistic mathematical model of initiation and malignant transformation in sporadic vestibular schwannoma

BACKGROUND

A vestibular schwannoma (VS) is a relatively rare, benign tumour of the eighth cranial nerve, often involving alterations to the gene NF2. Previous mathematical models of schwannoma incidence have not attempted to account for alterations in specific genes, and could not distinguish between nonsense mutations and loss of heterozygosity (LOH).

METHODS

Here, we present a mechanistic approach to modelling initiation and malignant transformation in schwannoma. Each parameter is associated with a specific gene or mechanism operative in Schwann cells, and can be determined by combining incidence data with empirical frequencies of pathogenic variants and LOH.

RESULTS

This results in new estimates for the base-pair mutation rate u = 4.48 × 10-10 and the rate of LOH = 2.03 × 10-6/yr in Schwann cells. In addition to new parameter estimates, we extend the approach to estimate the risk of both spontaneous and radiation-induced malignant transformation.

DISCUSSION

We conclude that radiotherapy is likely to have a negligible excess risk of malignancy for sporadic VS, with a possible exception of rapidly growing tumours.

BAP1 in cancer: epigenetic stability and genome integrity

Mutations in BAP1 have been identified in a hereditary cancer predisposition syndrome and in sporadic tumours. Individuals carrying familiar BAP1 monoallelic mutations display hypersusceptibility to exposure-associated cancers, such as asbestos-driven mesothelioma, thus BAP1 status has been postulated to participate in gene-environment interaction. Intriguingly, BAP1 functions display also a high degree of tissue dependency, associated to a peculiar cancer spectrum and cell types of specific functions. Mechanistically, BAP1 functions as an ubiquitin carboxy-terminal hydrolase (UCH) and controls regulatory ubiquitination of histones as well as degradative ubiquitination of a range of protein substrates. In this article we provide an overview of the most relevant findings on BAP1, underpinning its tissue specific tumour suppressor function. We also discuss the importance of its epigenetic role versus the control of protein stability in the regulation of genomic integrity.

Celastrol suppresses the growth of vestibular schwannoma in mice by promoting the degradation of β-catenin

Vestibular schwannoma (VS), one of characteristic tumors of neurofibromatosis type 2 (NF2), is an intracranial tumor that arises from Schwann cells of the vestibular nerve. VS results in hearing loss, tinnitus, dizziness, and even death, but there are currently no FDA-approved drugs for treatment. In this study, we established a high-throughput screening to discover effective compounds that could inhibit the viability of VS cells. Among 1019 natural products from the Korea Chemical Bank screened, we found that celastrol, a pentacyclic triterpene derived from a Tripterygium Wilfordi plant, exerted potent inhibitory effect on the viability of VS cells with an IC50 value of 0.5  µM. Celastrol (0.5, 1  µM) dose-dependently inhibited the proliferation of primary VS cells derived from VS patients. Celastrol also inhibited the growth, and induced apoptosis of two other VS cell lines (HEI-193 and SC4). Aberrant activation of Wnt/β-catenin signaling has been found in VS isolated from clinically defined NF2 patients. In HEI-193 and SC4 cells, we demonstrated that celastrol (0.1, 0.5 μM) dose-dependently inhibited TOPFlash reporter activity and protein expression of β-catenin, but not mRNA level of β-catenin. Furthermore, celastrol accelerated the degradation of β-catenin by promoting the formation of the β-catenin destruction complex. In nude mice bearing VS cell line SC4 allografts, administration of celastrol (1.25 mg · kg-1 · d-1, i.p. once every 3 days for 2 weeks) significantly suppressed the tumor growth without showing toxicity. Collectively, this study demonstrates that celastrol can inhibit Wnt/β-catenin signaling by promoting the degradation of β-catenin, consequently inhibiting the growth of VS.

Hallmarks of Cancer Expression in Oral Lichen Planus: A Scoping Review of Systematic Reviews and Meta-Analyses

Oral lichen planus (OLP) is a common chronic inflammatory disease of unknown etiology and likely autoimmune nature that is currently considered an oral potentially malignant disorder, implying that patients suffering from this process are at risk of developing oral cancer in their lifetime. The molecular alterations that develop in OLP and that make the affected oral epithelium predisposed to malignancy are unknown, although, as in other autoimmune diseases (ulcerative colitis, primary biliary cirrhosis, etc.), they may be linked to oncogenesis-promoting effects mediated by the inflammatory infiltrate. So far there is no in-depth knowledge on how these hallmarks of cancer are established in the cells of the oral epithelium affected by OLP. In this scoping review of systematic reviews and meta-analyses the state of evidence based knowledge in this field is presented, to point out gaps of evidence and to indicate future lines of research. MEDLINE, Embase, Cochrane Library and Dare were searched for secondary-level studies published before October 2022. The results identified 20 systematic reviews and meta-analyses critically appraising the hallmarks tumor-promoting inflammation (n = 17, 85%), sustaining proliferative signaling (n = 2, 10%), and evading growth suppressors (n = 1, 5%). No evidence was found for the other hallmarks of cancer in OLP. In conclusion, OLP malignization hypothetically derives from the aggressions of the inflammatory infiltrate and a particular type of epithelial response based on increased epithelial proliferation, evasion of growth-suppressive signals and lack of apoptosis. Future evidence-based research is required to support this hypothesis.

Covalent disruptor of YAP-TEAD association suppresses defective Hippo signaling

The transcription factor TEAD, together with its coactivator YAP/TAZ, is a key transcriptional modulator of the Hippo pathway. Activation of TEAD transcription by YAP has been implicated in a number of malignancies, and this complex represents a promising target for drug discovery. However, both YAP and its extensive binding interfaces to TEAD have been difficult to address using small molecules, mainly due to a lack of druggable pockets. TEAD is post-translationally modified by palmitoylation that targets a conserved cysteine at a central pocket, which provides an opportunity to develop cysteine-directed covalent small molecules for TEAD inhibition. Here, we employed covalent fragment screening approach followed by structure-based design to develop an irreversible TEAD inhibitor MYF-03-69. Using a range of in vitro and cell-based assays we demonstrated that through a covalent binding with TEAD palmitate pocket, MYF-03-69 disrupts YAP-TEAD association, suppresses TEAD transcriptional activity and inhibits cell growth of Hippo signaling defective malignant pleural mesothelioma (MPM). Further, a cell viability screening with a panel of 903 cancer cell lines indicated a high correlation between TEAD-YAP dependency and the sensitivity to MYF-03-69. Transcription profiling identified the upregulation of proapoptotic BMF gene in cancer cells that are sensitive to TEAD inhibition. Further optimization of MYF-03-69 led to an in vivo compatible compound MYF-03-176, which shows strong antitumor efficacy in MPM mouse xenograft model via oral administration. Taken together, we disclosed a story of the development of covalent TEAD inhibitors and its high therapeutic potential for clinic treatment for the cancers that are driven by TEAD-YAP alteration.

Integrated analysis of cervical squamous cell carcinoma cohorts from three continents reveals conserved subtypes of prognostic significance

Human papillomavirus (HPV)-associated cervical cancer is a leading cause of cancer deaths in women. Here we present an integrated multi-omic analysis of 643 cervical squamous cell carcinomas (CSCC, the most common histological variant of cervical cancer), representing patient populations from the USA, Europe and Sub-Saharan Africa and identify two CSCC subtypes (C1 and C2) with differing prognosis. C1 and C2 tumours can be driven by either of the two most common HPV types in cervical cancer (16 and 18) and while HPV16 and HPV18 are overrepresented among C1 and C2 tumours respectively, the prognostic difference between groups is not due to HPV type. C2 tumours, which comprise approximately 20% of CSCCs across these cohorts, display distinct genomic alterations, including loss or mutation of the STK11 tumour suppressor gene, increased expression of several immune checkpoint genes and differences in the tumour immune microenvironment that may explain the shorter survival associated with this group. In conclusion, we identify two therapy-relevant CSCC subtypes that share the same defining characteristics across three geographically diverse cohorts.

Human papillomavirus (HPV) is a known cause of cervical cancer. Here, the authors perform a multi-omic analysis using published cervical squamous cell carcinoma cohorts from the USA, Europe, and SubSaharan Africa and identify two cervical squamous cell carcinoma subtypes that display prognostic differences.

Application of MRI-Based Radiomics in Preoperative Prediction of NF2 Alteration in Intracranial Meningiomas

Purpose

This study aimed to investigate the feasibility of predicting NF2 mutation status based on the MR radiomic analysis in patients with intracranial meningioma.

Methods

This retrospective study included 105 patients with meningiomas, including 60 NF2-mutant samples and 45 wild-type samples. Radiomic features were extracted from magnetic resonance imaging scans, including T1-weighted, T2-weighted, and contrast T1-weighted images. Student’s t-test and LASSO regression were performed to select the radiomic features. All patients were randomly divided into training and validation cohorts in a 7:3 ratio. Five linear models (RF, SVM, LR, KNN, and xgboost) were trained to predict the NF2 mutational status. Receiver operating characteristic curve and precision-recall analyses were used to evaluate the model performance. Student’s t-tests were then used to compare the posterior probabilities of NF2 mut/loss prediction for patients with different NF2 statuses.

Results

Nine features had nonzero coefficients in the LASSO regression model. No significant differences was observed in the clinical features. Nine features showed significant differences in patients with different NF2 statuses. Among all machine learning algorithms, SVM showed the best performance. The area under curve and accuracy of the predictive model were 0.85; the F1-score of the precision-recall curve was 0.80. The model risk was assessed by plotting calibration curves. The p-value for the H-L goodness of fit test was 0.411 (p> 0.05), which indicated that the difference between the obtained model and the perfect model was statistically insignificant. The AUC of our model in external validation was 0.83.

Conclusion

A combination of radiomic analysis and machine learning showed potential clinical utility in the prediction of preoperative NF2 status. These findings could aid in developing customized neurosurgery plans and meningioma management strategies before postoperative pathology.

Phase separation in immune regulation and immune-related diseases

Phase separation is an emerging paradigm for understanding the biochemical interactions between proteins, DNA, and RNA. Research over the past decade has provided mounting evidence that phase separation modulates a great variety of cellular activities. Particularly, phase separation is directly relevant to immune signaling, immune cells, and immune-related diseases like cancer, neurodegenerative diseases, and even SARS-CoV-2. In this review, we summarized current knowledge of phase separation in immunology and emerging findings related to immune responses as they enable possible treatment approaches.

Gene replacement therapy in a schwannoma mouse model of neurofibromatosis type 2

Loss of function of the neurofibromatosis type 2 (NF2) tumor suppressor gene leads to the formation of schwannomas, meningiomas, and ependymomas, comprising ∼50% of all sporadic cases of primary nervous system tumors. NF2 syndrome is an autosomal dominant condition, with bi-allelic inactivation of germline and somatic alleles resulting in loss of function of the encoded protein merlin and activation of mammalian target of rapamycin (mTOR) pathway signaling in NF2-deficient cells. Here we describe a gene replacement approach through direct intratumoral injection of an adeno-associated virus vector expressing merlin in a novel human schwannoma model in nude mice. In culture, the introduction of an AAV1 vector encoding merlin into CRISPR-modified human NF2-null arachnoidal cells (ACs) or Schwann cells (SCs) was associated with decreased size and mTORC1 pathway activation consistent with restored merlin activity. In vivo, a single injection of AAV1-merlin directly into human NF2-null SC-derived tumors growing in the sciatic nerve of nude mice led to regression of tumors over a 10-week period, associated with a decrease in dividing cells and an increase in apoptosis, in comparison with vehicle. These studies establish that merlin re-expression via gene replacement in NF2-null schwannomas is sufficient to cause tumor regression, thereby potentially providing an effective treatment for NF2.

Landscape of genetic variants in sporadic meningiomas captured with clinical genomics

BACKGROUND

Meningiomas are the most common primary central nervous system tumor. Previous studies have characterized recurrent genetic alterations that can predict patient prognosis and potentially provide new avenues for therapeutic intervention. Continued efforts to characterize the genomic changes in meningioma samples can aid in the discovery of therapeutic targets and appropriate patient stratification.

METHODS

We performed targeted genomic sequencing on 25 primary and 2 recurrent meningiomas using a 500-gene panel, including canonical meningioma drivers. We further detail the genomic profiles and relevant clinical findings in three cases of angiomatous meningiomas and two recurrent atypical meningiomas.

RESULTS

Our approach uncovers a diverse landscape of genomic variants in meningioma samples including mutations in established meningioma-related genes NF2, AKT1, PIK3CA, and TRAF7. In addition to known meningioma drivers, we uncover variants in genes encoding other PI3K subunits, Notch/hedgehog/Wnt signaling pathway components, and chromatin regulators. We additionally identify 22 genes mutated across multiple samples. Three patients included in the study were diagnosed with angiomatous WHO grade I meningiomas, all three of which contained variants in the PI3K-AKT signaling pathway previously described to regulate tumor angiogenesis. Analysis of patient-matched primary and recurrent atypical meningiomas revealed clonal enrichment for mutations in the SWI/SNF complex subunits ARID1A and SMARCA4.

CONCLUSIONS

Targeted genomics implemented in neuro-oncology care can enhance our understanding of the genetic underpinnings of central nervous system tumors, including meningiomas. These molecular signatures may be clinically useful in dictating treatment strategies and patient follow-up.

Single-Cell RNA-Seq Reveals Heterogeneity of Cell Communications between Schwann Cells and Fibroblasts within Vestibular Schwannoma Microenvironment

Vestibular schwannomas (VSs), which develop from Schwann cells (SCs) of the vestibular nerve, are the most prevalent benign tumors of the cerebellopontine angle and internal auditory canal. Despite advances in treatment, the cellular components and mechanisms of VS tumor progression remain unclear. Herein, single-cell RNA-sequencing was performed on clinically surgically isolated VS samples and their cellular composition, including the heterogeneous SC subtypes, was determined. Advanced bioinformatics analysis revealed the associated biological functions, pseudotime trajectory, and transcriptional network of the SC subgroups. A tight intercellular communication between SCs and tumor-associated fibroblasts via integrin and growth factor signaling was observed and the gene expression differences in SCs and fibroblasts were shown to determine the heterogeneity of cellular communication in different individuals. These findings suggest a microenvironmental mechanism underlying the development of VS.

Focal adhesion kinase priming in pancreatic cancer, altering biomechanics to improve chemotherapy

The dense desmoplastic and fibrotic stroma is a characteristic feature of pancreatic ductal adenocarcinoma (PDAC), regulating disease progression, metastasis and response to treatment. Reciprocal interactions between the tumour and stroma are mediated by bidirectional integrin-mediated signalling, in particular by Focal Adhesion Kinase (FAK). FAK is often hyperactivated and overexpressed in aggressive cancers, promoting stromal remodelling and inducing tissue stiffness which can accelerate cancer cell proliferation, survival and chemoresistance. Therapeutic targeting of the PDAC stroma is an evolving area of interest for pre-clinical and clinical research, where a subtle reshaping of the stromal architecture prior to chemotherapy may prove promising in the clinical management of disease and overall patient survival. Here, we describe how transient stromal manipulation (or ‘priming’) via short-term FAK inhibition, rather than chronic treatment, can render PDAC cells exquisitely vulnerable to subsequent standard-of-care chemotherapy. We assess how our priming publication fits with the recent literature and describe in this perspective how this could impact future cancer treatment. This highlights the significance of treatment timing and warrants further consideration of anti-fibrotic therapies in the clinical management of PDAC and other fibrotic diseases.

Both YAP1-MAML2 and constitutively active YAP1 drive the formation of tumors that resemble NF2 mutant meningiomas in mice

YAP1 is a transcriptional coactivator regulated by the Hippo signaling pathway, including NF2. Meningiomas are the most common primary brain tumors; a large percentage exhibit heterozygous loss of chromosome 22 (harboring the NF2 gene) and functional inactivation of the remaining NF2 copy, implicating oncogenic YAP activity in these tumors. Recently, fusions between YAP1 and MAML2 have been identified in a subset of pediatric NF2 wild-type meningiomas. Here, we show that human YAP1-MAML2-positive meningiomas resemble NF2 mutant meningiomas by global and YAP-related gene expression signatures. We then show that expression of YAP1-MAML2 in mice induces tumors that resemble human YAP1 fusion-positive and NF2 mutant meningiomas by gene expression. We demonstrate that YAP1-MAML2 primarily functions by exerting TEAD-dependent YAP activity that is resistant to Hippo signaling. Treatment with YAP-TEAD inhibitors is sufficient to inhibit the viability of YAP1-MAML2-driven mouse tumors ex vivo. Finally, we show that expression of constitutively active YAP1 (S127/397A-YAP1) is sufficient to induce similar tumors, suggesting that the YAP component of the gene fusion is the critical driver of these tumors. In summary, our results implicate YAP1-MAML2 as a causal oncogenic driver and highlight TEAD-dependent YAP activity as an oncogenic driver in YAP1-MAML2 fusion meningioma as well as NF2 mutant meningioma in general.

Matched Paired Primary and Recurrent Meningiomas Points to Cell-Death Program Contributions to Genomic and Epigenomic Instability along Tumor Progression

Meningioma (MN) is an important cause of disability, and predictive tools for estimating the risk of recurrence are still scarce. The need for objective and cost-effective techniques addressed to this purpose is well known. In this study, we present methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) as a friendly method for deepening the understanding of the mechanisms underlying meningioma progression. A large follow-up allowed us to obtain 50 samples, which included the primary tumor of 20 patients in which half of them are suffering one recurrence and the other half are suffering more than one. We histologically characterized the samples and performed MS-MLPA assays validated by FISH to assess their copy number alterations (CNA) and epigenetic status. Interestingly, we determined the increase in tumor instability with higher values of CNA during the progression accompanied by an increase in epigenetic damage. We also found a loss of HIC1 and the hypermethylation of CDKN2B and PTEN as independent prognostic markers. Comparison between grade 1 and higher primary MN's self-evolution pointed to a central role of GSTP1 in the first stages of the disease. Finally, a high rate of alterations in genes that are related to apoptosis and autophagy, such as DAPK1, PARK2, BCL2, FHIT, or VHL, underlines an important influence on cell-death programs through different pathways.

Novel Driver Strength Index highlights important cancer genes in TCGA PanCanAtlas patients

Background

Cancer driver genes are usually ranked by mutation frequency, which does not necessarily reflect their driver strength. We hypothesize that driver strength is higher for genes preferentially mutated in patients with few driver mutations overall, because these few mutations should be strong enough to initiate cancer.

Methods

We propose formulas for the Driver Strength Index (DSI) and the Normalized Driver Strength Index (NDSI), the latter independent of gene mutation frequency. We validate them using TCGA PanCanAtlas datasets, established driver prediction algorithms and custom computational pipelines integrating SNA, CNA and aneuploidy driver contributions at the patient-level resolution.

Results

DSI and especially NDSI provide substantially different gene rankings compared to the frequency approach. E.g., NDSI prioritized members of specific protein families, including G proteins GNAQ, GNA11 and GNAS, isocitrate dehydrogenases IDH1 and IDH2, and fibroblast growth factor receptors FGFR2 and FGFR3. KEGG analysis shows that top NDSI-ranked genes comprise EGFR/FGFR2/GNAQ/GNA11-NRAS/HRAS/KRAS-BRAF pathway, AKT1-MTOR pathway, and TCEB1-VHL-HIF1A pathway.

Conclusion

Our indices are able to select for driver gene attributes not selected by frequency sorting, potentially for driver strength. Genes and pathways prioritized are likely the strongest contributors to cancer initiation and progression and should become future therapeutic targets.

Hallmarks of Cancer Applied to Oral and Oropharyngeal Carcinogenesis: A Scoping Review of the Evidence Gaps Found in Published Systematic Reviews

In 2000 and 2011, Hanahan and Weinberg published two papers in which they defined the characteristics that cells must fulfil in order to be considered neoplastic cells in all types of tumours that affect humans, which the authors called "hallmarks of cancer". These papers have represented a milestone in our understanding of the biology of many types of cancers and have made it possible to reach high levels of scientific evidence in relation to the prognostic impact that these hallmarks have on different tumour types. However, to date, there is no study that globally analyses evidence-based knowledge on the importance of these hallmarks in oral and oropharyngeal squamous cell carcinomas. For this reason, we set out to conduct this scoping review of systematic reviews with the aim of detecting evidence gaps in relation to the relevance of the cancer hallmarks proposed by Hanahan and Weinberg in oral and oropharyngeal cancer, and oral potentially malignant disorders, and to point out future lines of research in this field.

CUDC907, a dual phosphoinositide-3 kinase/histone deacetylase inhibitor, promotes apoptosis of NF2 Schwannoma cells

Neurofibromatosis Type 2 (NF2) is a rare tumor disorder caused by pathogenic variants of the merlin tumor suppressor encoded by NF2. Patients develop vestibular schwannomas (VS), peripheral schwannomas, meningiomas, and ependymomas. There are no approved drug therapies for NF2. Previous work identified phosphoinositide-3 kinase (PI3K) as a druggable target. Here we screened PI3K pathway inhibitors for efficacy in reducing viability of human schwannoma cells. The lead compound, CUDC907, a dual histone deacetylase (HDAC)/PI3K inhibitor, was further evaluated for its effects on isolated and nerve-grafted schwannoma model cells, and primary VS cells. CUDC907 (3 nM IG50) reduced human merlin deficient Schwann cell (MD-SC) viability and was 5-100 fold selective for MD over WT-SCs. CUDC907 (10 nM) promoted cell cycle arrest and caspase-3/7 activation within 24 h in human MD-SCs. Western blots confirmed a dose-dependent increase in acetylated lysine and decreases in pAKT and YAP. CUDC907 decreased tumor growth rate by 44% in a 14-day treatment regimen, modulated phospho-target levels, and decreased YAP levels. In five primary VS, CUDC907 decreased viability, induced caspase-3/7 cleavage, and reduced YAP levels. Its efficacy correlated with basal phospho-HDAC2 levels. CUDC907 has cytotoxic activity in NF2 schwannoma models and primary VS cells and is a candidate for clinical trials.

Liquid-liquid phase separation in tumor biology

Liquid-liquid phase separation (LLPS) is a novel principle for explaining the precise spatial and temporal regulation in living cells. LLPS compartmentalizes proteins and nucleic acids into micron-scale, liquid-like, membraneless bodies with specific functions, which were recently termed biomolecular condensates. Biomolecular condensates are executors underlying the intracellular spatiotemporal coordination of various biological activities, including chromatin organization, genomic stability, DNA damage response and repair, transcription, and signal transduction. Dysregulation of these cellular processes is a key event in the initiation and/or evolution of cancer, and emerging evidence has linked the formation and regulation of LLPS to malignant transformations in tumor biology. In this review, we comprehensively summarize the detailed mechanisms of biomolecular condensate formation and biophysical function and review the recent major advances toward elucidating the multiple mechanisms involved in cancer cell pathology driven by aberrant LLPS. In addition, we discuss the therapeutic perspectives of LLPS in cancer research and the most recently developed drug candidates targeting LLPS modulation that can be used to combat tumorigenesis.

The Hippo pathway drives the cellular response to hydrostatic pressure

Cells need to rapidly and precisely react to multiple mechanical and chemical stimuli in order to ensure precise context-dependent responses. This requires dynamic cellular signalling events that ensure homeostasis and plasticity when needed. A less well-understood process is cellular response to elevated interstitial fluid pressure, where the cell senses and responds to changes in extracellular hydrostatic pressure. Here, using quantitative label-free digital holographic imaging, combined with genome editing, biochemical assays and confocal imaging, we analyse the temporal cellular response to hydrostatic pressure. Upon elevated cyclic hydrostatic pressure, the cell responds by rapid, dramatic and reversible changes in cellular volume. We show that YAP and TAZ, the co-transcriptional regulators of the Hippo signalling pathway, control cell volume and that cells without YAP and TAZ have lower plasma membrane tension. We present direct evidence that YAP/TAZ drive the cellular response to hydrostatic pressure, a process that is at least partly mediated via clathrin-dependent endocytosis. Additionally, upon elevated oscillating hydrostatic pressure, YAP/TAZ are activated and induce TEAD-mediated transcription and expression of cellular components involved in dynamic regulation of cell volume and extracellular matrix. This cellular response confers a feedback loop that allows the cell to robustly respond to changes in interstitial fluid pressure.

Molecular Alterations in Malignant Pleural Mesothelioma: A Hope for Effective Treatment by Targeting YAP

Malignant pleural mesothelioma is a rare and aggressive neoplasm, which has primarily been attributed to the exposure to asbestos fibers (83% of cases); yet, despite a ban of using asbestos in many countries, the incidence of malignant pleural mesothelioma failed to decline worldwide. While little progress has been made in malignant pleural mesothelioma diagnosis, bevacizumab at first, then followed by double immunotherapy (nivolumab plus ipilumumab), were all shown to improve survival in large phase III randomized trials. The morphological analysis of the histological subtyping remains the primary indicator for therapeutic decision making at an advanced disease stage, while a platinum-based chemotherapy regimen combined with pemetrexed, either with or without bevacizumab, is still the main treatment option. Consequently, malignant pleural mesothelioma still represents a significant health concern owing to poor median survival (12-18 months). Given this context, both diagnosis and therapy improvements require better knowledge of the molecular mechanisms underlying malignant pleural mesothelioma's carcinogenesis and progression. Hence, the Hippo pathway in malignant pleural mesothelioma initiation and progression has recently received increasing attention, as the aberrant expression of its core components may be closely related to patient prognosis. The purpose of this review was to provide a critical analysis of our current knowledge on these topics, the main focus being on the available evidence concerning the role of each Hippo pathway's member as a promising biomarker, enabling detection of the disease at earlier stages and thus improving prognosis.

Effect of AR42 in Primary Vestibular Schwannoma Cells and a Xenograft Model of Vestibular Schwannoma

HYPOTHESIS

AR42, a histone deacetylase (HDAC) inhibitor, reduces viability of primary vestibular schwannoma (VS) cells and delays tumor progression and hearing loss (HL) in a xenograft model of VS.

BACKGROUND

The impact of HDAC expression on AR42 response in primary VS cells is unknown, as well as the effects of AR42 on VS-associated HL and imbalance.

METHODS

Primary human VS cells (n = 7) were treated with AR42 (0-3.0 μM), and viability assays were conducted. Immunohistochemistry and western blotting for phosphorylated-HDAC2 (pHDAC2) were performed on tumor chunks. Pharmacokinetic studies were conducted in Fischer rats using mass spectrometry. Merlin-deficient Schwann cells were grafted onto cochleovestibular nerves of immunodeficient rats and treated with vehicle (n=7) or AR42 (25 mg/kg/day for 4weeks; n=12). Tumor bioluminescence imaging, auditory brainstem response (ABR), and rotarod tests were conducted to 6weeks. Final tumor weight and toxicities were measured.

RESULTS

AR42 caused dose-dependent reductions in viability of VS cells. Tumors with higher pHDAC2:HDAC2 ratios had greater reductions in viability with AR42. On pharmacokinetic studies, AR42 reached peak levels in nerve ~24 hours after oral administration. Although AR42-treated rats demonstrated mean ABR threshold shifts ~10 to 20 dB lower than controls, this did not persist nor reach significance. When compared to controls, AR42 did not affect tumor bioluminescence, tumor weight, and rotarod measurements.

CONCLUSIONS

Response of primary VS cells to AR42 may be influenced by pHDAC2 expression in tumor. Although AR42 may delay HL in our xenograft model, it did not halt tumor growth or vestibular dysfunction. Further investigations are warranted to evaluate the AR42 effectiveness in NF2-associated VS.

Targeting Ferroptosis Pathway to Combat Therapy Resistance and Metastasis of Cancer

Ferroptosis is an iron-dependent regulated form of cell death caused by excessive lipid peroxidation. This form of cell death differed from known forms of cell death in morphological and biochemical features such as apoptosis, necrosis, and autophagy. Cancer cells require higher levels of iron to survive, which makes them highly susceptible to ferroptosis. Therefore, it was found to be closely related to the progression, treatment response, and metastasis of various cancer types. Numerous studies have found that the ferroptosis pathway is closely related to drug resistance and metastasis of cancer. Some cancer cells reduce their susceptibility to ferroptosis by downregulating the ferroptosis pathway, resulting in resistance to anticancer therapy. Induction of ferroptosis restores the sensitivity of drug-resistant cancer cells to standard treatments. Cancer cells that are resistant to conventional therapies or have a high propensity to metastasize might be particularly susceptible to ferroptosis. Some biological processes and cellular components, such as epithelial–mesenchymal transition (EMT) and noncoding RNAs, can influence cancer metastasis by regulating ferroptosis. Therefore, targeting ferroptosis may help suppress cancer metastasis. Those progresses revealed the importance of ferroptosis in cancer, In order to provide the detailed molecular mechanisms of ferroptosis in regulating therapy resistance and metastasis and strategies to overcome these barriers are not fully understood, we described the key molecular mechanisms of ferroptosis and its interaction with signaling pathways related to therapy resistance and metastasis. Furthermore, we summarized strategies for reversing resistance to targeted therapy, chemotherapy, radiotherapy, and immunotherapy and inhibiting cancer metastasis by modulating ferroptosis. Understanding the comprehensive regulatory mechanisms and signaling pathways of ferroptosis in cancer can provide new insights to enhance the efficacy of anticancer drugs, overcome drug resistance, and inhibit cancer metastasis.

Gatekeeping role of Nf2/Merlin in vascular tip EC induction through suppression of VEGFR2 internalization

In sprouting angiogenesis, the precise mechanisms underlying how intracellular vascular endothelial growth factor receptor 2 (VEGFR2) signaling is higher in one endothelial cell (EC) compared with its neighbor and acquires the tip EC phenotype under a similar external cue are elusive. Here, we show that Merlin, encoded by the neurofibromatosis type 2 (NF2) gene, suppresses VEGFR2 internalization depending on VE-cadherin density and inhibits tip EC induction. Accordingly, endothelial Nf2 depletion promotes tip EC induction with excessive filopodia by enhancing VEGFR2 internalization in both the growing and matured vessels. Mechanistically, Merlin binds to the VEGFR2-VE-cadherin complex at cell-cell junctions and reduces VEGFR2 internalization-induced downstream signaling during tip EC induction. As a consequence, nonfunctional excessive sprouting occurs during tumor angiogenesis in EC-specific Nf2-deleted mice, leading to delayed tumor growth. Together, Nf2/Merlin is a crucial molecular gatekeeper for tip EC induction, capillary integrity, and proper tumor angiogenesis by suppressing VEGFR2 internalization.

Validation of BET proteins as therapeutic targets in Neurofibromatosis type 2

Background

Neurofibromatosis type 2 (NF2) is an autosomal dominant genetic disease characterized by development of schwannomas on the VIIIth (vestibular) cranial nerves. Bromodomain and extra-terminal domain (BET) proteins regulate gene transcription and their activity is required in a variety of cancers including malignant peripheral nerve sheath tumors. The use of BET inhibitors as a therapeutic option to treat NF2 schwannomas has not been explored and is the focus of this study.

Methods

A panel of normal and NF2-null Schwann and schwannoma cell lines were used to characterize the impact of the BET inhibitor JQ1 in vitro and in vivo. The mechanism of action was explored by chromatin immunoprecipitation of the BET BRD4, phospho-kinase arrays and immunohistochemistry (IHC) of BRD4 in vestibular schwannomas.

Results

JQ1 inhibited proliferation of NF2-null schwannoma and Schwann cell lines in vitro and in vivo. Further, loss of NF2 by CRISPR deletion or siRNA knockdown increased sensitivity of cells to JQ1. Loss of function experiments identified BRD4, and to a lesser extent BRD2, as BET family members mediating the majority of JQ1 effects. IHC demonstrated elevated levels of BRD4 protein in human vestibular schwannomas. Analysis of signaling pathways effected by JQ1 treatment suggests that the effects of JQ1 treatment are mediated, at least in part, via inhibition of PI3K/Akt signaling.

Conclusions

NF2-deficient Schwann and schwannoma cells are sensitive to BET inhibition, primarily mediated by BRD4, which is overexpressed in human vestibular schwannomas. Our results suggest BRD4 regulates PI3K signaling and likely impedes NF2 schwannoma growth via this inhibition. These findings implicate BET inhibition as a therapeutic option for NF2-deficient schwannomas.

The application of cancer stem cell model in malignant mesothelioma

The high mortality rate of malignant pleural mesothelioma led to study the mechanisms for chemoresistance. The cancer stem cell (CSC) model has been proposed to explain chemoresistance. CSCs are characterized by self-renewal capacity, that is detected through tumor-initiating cell assays. As in other malignancies, many studies sought to identify surface markers to isolate CSCs from malignant mesothelioma. Other studies characterized malignant mesothelioma CSCs for the expression of specific genes involved in stemness and the expression of proteins involved in chemoresistance. However, the main methods to characterize isolated CSCs include sphere formation, invasiveness, tumor-initiating capacity and expression of specific surface markers. The better knowledge of malignant mesothelioma CSCs allowed exploring new potential targets to develop specific treatments.

Clinical Significance of Molecular Alterations and Systemic Therapy for Meningiomas: Where Do We Stand?

Meningiomas are common intracranial tumors that can be treated successfully in most cases with surgical resection and/or adjuvant radiotherapy. However, approximately 20% of patients show an aggressive clinical course with tumor recurrence or progressive disease, resulting in significant morbidity and increased mortality. Despite several studies that have investigated different cytotoxic agents in aggressive meningiomas in the past several years, limited evidence of efficacy and clinical benefit has been reported thus far. Novel molecular alterations have been linked to a particular clinicopathological phenotype and have been correlated with grading, location, and prognosis of meningiomas. In this regard, SMO, AKT, and PIK3CA mutations are typical of anterior skull base meningiomas, whereas KLF4 mutations are specific for secretory histology, and BAP1 alterations are common in progressive rhabdoid meningiomas. Alterations in TERT, DMD, and BAP1 correlate with poor outcomes. Moreover, some actionable mutations, including SMO, AKT1, and PIK3CA, regulate meningioma growth and are under investigation in clinical trials. PD-L1 and/or M2 macrophage expression in the microenvironment provides evidence for the investigation of immunotherapy in progressive meningiomas.

Neurofibromatosis: New Clinical Challenges in the Era of COVID-19

Rare diseases constitute a wide range of disorders thus defined for their low prevalence. However, taken together, rare diseases impact a considerable percentage of the world population, thus representing a public healthcare problem. In particular, neurofibromatoses are autosomal-dominant genetic disorders that include type 1 neurofibromatosis (NF1), type 2 neurofibromatosis (NF2) and schwannomatosis. Each of the three types is a genetically distinct disease with an unpredictable clinical course and for which there is still no resolutive cure. Therefore, a personalized therapeutic approach directed at improving the symptomatology as well as the search for new pharmacological strategies for the management of neurofibromatosis represents a priority for positive outcomes for affected patients. The coronavirus disease 2019 (COVID-19) pandemic has severely affected health systems around the world, impacting the provision of medical care and modifying clinical surveillance along with scientific research procedures. COVID-19 significantly worsened exchanges between healthcare personnel and neurofibromatosis patients, precluding continuous clinical monitoring in specialized clinic centers. In this new scenario, our article presents, for the first time, a comprehensive literature review on the clinical challenges for neurofibromatosis clinical care and research during the COVID-19 pandemic health emergency. The review was performed through PubMed (Medline) and Google Scholar databases until December 2021.

Identification and Management of Aggressive Meningiomas

Meningiomas are common primary central nervous system tumors derived from the meninges, with management most frequently entailing serial monitoring or a combination of surgery and/or radiation therapy. Although often considered benign lesions, meningiomas can not only be surgically inaccessible but also exhibit aggressive growth and recurrence. In such cases, adjuvant radiation and systemic therapy may be required for tumor control. In this review, we briefly describe the current WHO grading scale for meningioma and provide demonstrative cases of treatment-resistant meningiomas. We also summarize frequently observed molecular abnormalities and their correlation with intracranial location and recurrence rate. We then describe how genetic and epigenetic features might supplement or even replace histopathologic features for improved identification of aggressive lesions. Finally, we describe the role of surgery, radiotherapy, and ongoing systemic therapy as well as precision medicine clinical trials for the treatment of recurrent meningioma.

Practical Genetics for the Neuroradiologist: Adding Value in Neurogenetic Disease

Genetic discoveries have transformed our understanding of many neurologic diseases. Identification of specific causal pathogenic variants has improved understanding of pathophysiology and enabled replacement of many confusing eponyms and acronyms with more meaningful and clinically relevant genetics-based terminology. In this era of rapid scientific advancement, multidisciplinary collaboration among pediatricians, neurologists, geneticists, radiologists, and other members of the health care team is increasingly important in the care of patients with genetic neurologic diseases. Radiologists familiar with neurogenetic disease add value by (1) recognizing constellations of characteristic imaging findings that are associated with a genetic disease before one is clinically suspected; (2) predicting the most likely genotypes for a given imaging phenotype in clinically suspected genetic disease; and (3) providing detailed and accurate descriptions of the imaging phenotype in challenging cases with unknown or uncertain genotypes. This review aims to increase awareness and understanding of pathogenic variants relating to neurologic disease by (1) briefly reviewing foundational knowledge of chromosomes, inheritance patterns, and mutagenesis; (2) providing concrete examples of and detailed information about specific neurologic diseases resulting from pathogenic variants; and (3) highlighting clinical and imaging features that are of greatest relevance for the radiologist.

Analysis of induced pluripotent stem cell clones derived from a patient with mosaic neurofibromatosis type 2

The diagnosis of mosaicism is challenging in patients with neurofibromatosis type 2 (NF2) subset due to low variant allele frequency. In this study, we generated induced pluripotent stem cells (iPSCs) were generated from a patient clinically diagnosed with NF2 based on multiple schwannomas, including bilateral vestibular schwannomas and meningiomas. Genetic analysis of the patient's mononuclear cells (MNCs) from peripheral blood failed to detect NF2 alteration but successfully found p.Q65X (c.193C>T) mutation in all separate tumors with three intracranial meningiomas and one intraorbital schwannoma, and confirming mosaicism diagnosis in NF2 alteration using deep sequencing. Five different clones with patient-derived iPSCs were established from MNCs in peripheral blood, which showed sufficient expression of pluripotent markers. Genetic analysis showed that one of five generated iPSC lines from MNCs had the same p.Q65X mutation as that found in NF2. There was no significant difference in the expression of genes related to NF2 between iPSC clones with the wild-type and mutant NF2. In this case, clonal expansion of mononuclear bone marrow-derived stem cells recapitulated mosaicism's genetic alteration in NF2. Patient-derived iPSCs from mosaic NF2 would contribute to further functional research of NF2 alteration.

Gene Editing with CRISPR/Cas Methodology and Thyroid Cancer: Where Are We?

Simple Summary

The advent of genomic editing with CRISPR/Cas9 has transformed the way we manipulate the genome, and has facilitated the investigation of tumor cell biology in vitro and in vivo. Not only we can modify genome sequence to blunt an overactivated gene or correct a mutation, but also we may modulate gene expression using CRISPR/Cas system. In this review, we present the basics of CRISPR/Cas methodology, its components and how to start a CRISPR/Cas experiment; Moreover, we present how CRISPR/Cas methodology has been applied to study the function of coding and noncoding genes in thyroid cancer and provided insights into cancer biology.

Abstract

Important advances on the role of genetic alterations in thyroid cancer have been achieved in the last two decades. One key reason is linked to the development of technical approaches that allowed for the mimicking of genetic alterations in vitro and in vivo and, more recently, the gene editing methodology. The CRISPR/Cas methodology has emerged as a tangible tool for editing virtually any DNA sequence in the genome. To induce a double-strand break and programmable gene editing, Cas9 endonuclease is guided by a single-guide RNA (sgRNA) that is complementary to the target sequence in DNA. The gene editing per se occurs as the cells repair the broken DNA and may erroneously change the original DNA sequence. In this review, we explore the principles of the CRISPR/Cas system to facilitate an understanding of the mainstream technique and its applications in gene editing. Furthermore, we explored new applications of CRISPR/Cas for gene modulation without changing the DNA sequence and provided a Dry Lab experience for those who are interested in starting “CRISPRing” any given gene. In the last section, we will discuss the progress in the knowledge of thyroid cancer biology fostered by the CRISPR/Cas gene editing tools.

Whole Blood Transcriptional Fingerprints of High-Grade Glioma and Longitudinal Tumor Evolution under Carbon Ion Radiotherapy

Simple Summary

Particle therapy with carbon ions is a promising novel option for the treatment of recurrent high-grade glioma (rHGG). Lack of initial and sequential biopsies limits the investigation of rHGG evolution under therapy. We hypothesized that peripheral blood transcriptome derived from liquid biopsies (lbx) as a minimal invasive method may provide a useful decision support for identification of glioma grade and provide novel means for longitudinal molecular monitoring of tumor evolution under carbon ion irradiation (CIR). We demonstrate feasibility and report patient, tumor and treatment fingerprints in whole blood transcriptomes of rHGG patients with pre-CIR and three post-CIR time points.

Abstract

Purpose: To assess the value of whole blood transcriptome data from liquid biopsy (lbx) in recurrent high-grade glioma (rHGG) patients for longitudinal molecular monitoring of tumor evolution under carbon ion irradiation (CIR). Methods: Whole blood transcriptome (WBT) analysis (Illumina HumanHT-12 Expression BeadChips) was performed in 14 patients with rHGG pre re-irradiation (reRT) with CIR and 3, 6 and 9 weeks post-CIR (reRT grade III:5, 36%, IV:9, 64%). Patients were irradiated with 30, 33, 36 GyRBE (n = 5, 6, 3) in 3GyRBE per fraction. Results: WTB analysis showed stable correlation with treatment characteristics and patients tumor grade, indicating a preserved tumor origin specific as well as dynamic transcriptional fingerprints of peripheral blood cells. Initial histopathologic tumor grade was indirectly associated with TMEM173 (STING), DNA-repair (ATM, POLD4) and hypoxia related genes. DNA-repair, chromatin remodeling (LIG1, SMARCD1) and immune response (FLT3LG) pathways were affected post-CIR. Longitudinal WTB fingerprints identified two distinct trajectories of rHGG evolution, characterized by differential and prognostic CRISPLD2 expression pre-CIR. Conclusions: Lbx based WTB analysis holds the potential for molecular stratification of rHGG patients and therapy monitoring. We demonstrate the feasibility of the peripheral blood transcriptome as a sentinel organ for identification of patient, tumor characteristics and CIR specific fingerprints in rHGG.

Apoptosis in Type 2 Diabetes: Can It Be Prevented? Hippo Pathway Prospects

Diabetes mellitus is a heterogeneous disease of complex etiology and pathogenesis. Hyperglycemia leads to many serious complications, but also directly initiates the process of β cell apoptosis. A potential strategy for the preservation of pancreatic β cells in diabetes may be to inhibit the implementation of pro-apoptotic pathways or to enhance the action of pancreatic protective factors. The Hippo signaling pathway is proposed and selected as a target to manipulate the activity of its core proteins in therapy-basic research. MST1 and LATS2, as major upstream signaling kinases of the Hippo pathway, are considered as target candidates for pharmacologically induced tissue regeneration and inhibition of apoptosis. Manipulating the activity of components of the Hippo pathway offers a wide range of possibilities, and thus is a potential tool in the treatment of diabetes and the regeneration of β cells. Therefore, it is important to fully understand the processes involved in apoptosis in diabetic states and completely characterize the role of this pathway in diabetes. Therapy consisting of slowing down or stopping the mechanisms of apoptosis may be an important direction of diabetes treatment in the future.

Syndromic Hydrocephalus

Hydrocephalus, the abnormal accumulation and impaired circulation/clearance of cerebrospinal fluid, occurs as a common phenotypic feature of a diverse group of genetic syndromes. In this review, we outline the genetic mutations, pathogenesis, and accompanying symptoms underlying syndromic hydrocephalus in the context of: L1 syndrome, syndromic craniosynostoses, achondroplasia, NF 1/2, Down's syndrome, tuberous sclerosis, Walker-Warburg syndrome, primary ciliary dyskinesia, and osteogenesis imperfecta. Further, we discuss emerging genetic variants associated with syndromic hydrocephalus.

Molecular Classification and Therapeutic Targets in Ependymoma

Ependymoma is a biologically diverse tumor wherein molecular classification has superseded traditional histological grading based on its superior ability to characterize behavior, prognosis, and possible targeted therapies. The current, updated molecular classification of ependymoma consists of ten distinct subgroups spread evenly among the spinal, infratentorial, and supratentorial compartments, each with its own distinct clinical and molecular characteristics. In this review, the history, histopathology, standard of care, prognosis, oncogenic drivers, and hypothesized molecular targets for all subgroups of ependymoma are explored. This review emphasizes that despite the varied behavior of the ependymoma subgroups, it remains clear that research must be performed to further elucidate molecular targets for these tumors. Although not all ependymoma subgroups are oncologically aggressive, development of targeted therapies is essential, particularly for cases where surgical resection is not an option without causing significant morbidity. The development of molecular therapies must rely on building upon our current understanding of ependymoma oncogenesis, as well as cultivating transfer of knowledge based on malignancies with similar genomic alterations.

Primary Vestibular Schwannoma Cells Activate p21 and RAD51-Associated DNA Repair Following Radiation-Induced DNA Damage

HYPOTHESIS

Vestibular Schwannoma (VS) can avoid cell death following radiation injury by entering cell cycle arrest and activating RAD51-related DNA repair.

BACKGROUND

Although the radiobiology of various cancers is well-studied, the radiobiological effects in VS are poorly understood. In this study, we describe how VS cells enter cell cycle arrest (through p21 expression), activate DNA repair (through RAD51 upregulation), and avoid cell death after radiation-induced double-stranded breaks (DSB) in DNA (as measured by γ-H2AX).

METHODS

Primary human VS cells were cultured on 96-well plates and 16-well culture slides at 10,000 cells/well and exposed to either 0 or 18 Gray of radiation. Viability assays were performed at 96 h in vitro. Immunofluorescence for γ-H2AX, RAD51, and p21 was performed at 6 h.

RESULTS

Radiation (18 Gy) induced the expression of γ-H2AX, p21, and RAD51 in six cultured VS, suggesting that irradiated VS acquire DSBs, enter cell cycle arrest, and initiate RAD51 DNA repair to evade cell death. However, viability studies demonstrate variable responses in individual VS cells with 3 of 6 VS showing radiation resistance to 18 Gy. On further analyses, radiation-resistant VS cells expressed significantly more p21 than radiation-responsive tumors.

CONCLUSIONS

In response to radiation-induced DNA damage, primary VS cells can enter cell cycle arrest and express RAD51 DNA repair mechanisms to avoid cell death. Radioresistant VS cells may mount a more robust p21 response to ensure sufficient time for DNA repair. Further investigation into DNA repair proteins and cell cycle checkpoints may provide important insight on the radiobiology of VS and mechanisms for resistance.

Reviewing Schwannoma-Hemangioma Composite Tumors With Their Tumorigenetic Molecular Pathways and Associated Syndromic Manifestations

Schwannomas are common peripheral nerve sheath tumors. Cavernous hemangiomas are vascular tumors that can affect any organ system. The coexistence of cavernous hemangioma with peripheral nervous system neoplasms is a rare occurrence. So far, 37 cases have been documented, and they have been divided into two categories: conjoined association (neoplasms discovered within the tumor tissue) and discrete association (neoplasms discovered outside the tumor tissue, thus placing neoplasms and tumors in close proximity but in different locations). Schwannomas and neurofibromas are the most prevalent tumors linked to cavernous hemangiomas that have been documented. The author provides a comprehensive review of all such cases published in the past with an emphasis on the implications of their tumorigenetic molecular pathways and syndromic manifestations.

RKIP Induction Promotes Tumor Differentiation via SOX2 Degradation in NF2-Deficient Conditions

Loss of NF2 (merlin) has been suggested as a genetic cause of neurofibromatosis type 2 and malignant peripheral nerve sheath tumor (MPNST). Previously, we demonstrated that NF2 sustained TGFβ receptor 2 (TβR2) expression and reduction or loss of NF2 activated non-canonical TGFβ signaling, which reduced Raf kinase inhibitor protein (RKIP) expression via TβR1 kinase activity. Here, we show that a selective RKIP inducer (novel chemical, Nf18001) inhibits tumor growth and promotes schwannoma cell differentiation into mature Schwann cells under NF2-deficient conditions. In addition, Nf18001 is not cytotoxic to cells expressing NF2 and is not disturb canonical TGFβ signaling. Moreover, the novel chemical induces expression of SOX10, a marker of differentiated Schwann cells, and promotes nuclear export and degradation of SOX2, a stem cell factor. Treatment with Nf18001 inhibited tumor growth in an allograft model with mouse schwannoma cells. These results strongly suggest that selective RKIP inducers could be useful for the treatment of neurofibromatosis type 2 as well as NF2-deficient MPNST. IMPLICATIONS: This study identifies that a selective RKIP inducer inhibits tumor growth and promotes schwannoma cell differentiation under NF2-deficient conditions by reducing SOX2 and increasing SOX10 expression.

Use of preclinical models for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer most commonly caused by prior exposure to asbestos. Median survival is 12-18 months, since surgery is ineffective and chemotherapy offers minimal benefit. Preclinical models that faithfully recapitulate the genomic and histopathological features of cancer are critical for the development of new treatments. The most commonly used models of MPM are two-dimensional cell lines established from primary tumours or pleural fluid. While these have provided some important insights into MPM biology, these cell models have significant limitations. In order to address some of these limitations, spheroids and microfluidic chips have more recently been used to investigate the role of the three-dimensional environment in MPM. Efforts have also been made to develop animal models of MPM, including asbestos-induced murine tumour models, MPM-prone genetically modified mice and patient-derived xenografts. Here, we discuss the available in vitro and in vivo models of MPM and highlight their strengths and limitations. We discuss how newer technologies, such as the tumour-derived organoids, might allow us to address the limitations of existing models and aid in the identification of effective treatments for this challenging-to-treat disease.

NF2 Gene Participates in Regulation of the Cell Cycle of Meningiomas by Restoring Spindle Assembly Checkpoint Function and Inhibiting the Binding of Cdc20 Protein to Anaphase Promoting Complex/Cyclosome

BACKGROUND

The neurofibromatosis type 2 (NF2) gene mutation is the leading genetic event in meningiomas, usually accompanied by malignant features. Dysfunction of the spindle assembly checkpoint (SAC) induces tumorigenesis. However, the crosstalk between NF2 and SAC in meningiomas remains unclear.

METHODS

Cell proliferation, invasion, apoptosis, and cell cycle of meningiomas were determined by cell counting kit-8 assay, transwell assay, and flow cytometry, respectively. The expression of SAC in meningioma cells was detected by quantitative real-time polymerase chain reaction and Western blot. The interaction between anaphase promoting complex/cyclosome (APC/C) and cell division cycle 20 (Cdc20) protein in meningioma cells was further explored by co-immunoprecipitation.

RESULTS

We found that the expression of NF2/merlin was low or absent in malignant meningiomas. Overexpression of NF2 suppressed the proliferation and invasion of meningioma cells, prolonged the G₂/M phase, and elevated the expression of SAC proteins at posttranscription. Furthermore, the interaction between APC/C and Cdc20 was inhibited by NF2.

CONCLUSIONS

Our findings suggested that NF2 might restore SAC function by impairing the binding of APC/C and Cdc20, thereby limiting the mitotic rate and inhibiting proliferation of meningiomas.

Interferon induction held captive in tumor cells

Unusual nucleic acids activate innate immunity and may be present in transformed cells. Meng et al. (2021) find that cancer-associated mutations in NF2 turn this tumor suppressor into a potent antagonist of DNA- and RNA-induced innate immune signaling.

Induced phase separation of mutant NF2 imprisons the cGAS-STING machinery to abrogate antitumor immunity

Missense mutations of the tumor suppressor Neurofibromin 2 (NF2/Merlin/schwannomin) result in sporadic to frequent occurrences of tumorigenesis in multiple organs. However, the underlying pathogenicity of NF2-related tumorigenesis remains mostly unknown. Here we found that NF2 facilitated innate immunity by regulating YAP/TAZ-mediated TBK1 inhibition. Unexpectedly, patient-derived individual mutations in the FERM domain of NF2 (NF2m) converted NF2 into a potent suppressor of cGAS-STING signaling. Mechanistically, NF2m gained extreme associations with IRF3 and TBK1 and, upon innate nucleic acid sensing, was directly induced by the activated IRF3 to form cellular condensates, which contained the PP2A complex, to eliminate TBK1 activation. Accordingly, NF2m robustly suppressed STING-initiated antitumor immunity in cancer cell-autonomous and -nonautonomous murine models, and NF2m-IRF3 condensates were evident in human vestibular schwannomas. Our study reports phase separation-mediated quiescence of cGAS-STING signaling by a mutant tumor suppressor and reveals gain-of-function pathogenesis for NF2-related tumors by regulating antitumor immunity.