The neurofibromatosis type 2 (NF2) gene, known for encoding the tumor suppressor protein Merlin, is central to the study of tumorigenesis and associated cellular processes. This review comprehensively examines the multifaceted role of NF2/Merlin, detailing its structural characteristics, functional diversity, and involvement in various signaling pathways such as Wnt/β-catenin, Hippo, TGF-β, RTKs, mTOR, Notch, and Hedgehog. These pathways are crucial for cellular growth, proliferation, and differentiation. NF2 mutations are specifically linked to the development of schwannomas, meningiomas, and ependymomas, although the precise mechanisms of tumor formation in these specific cell types remain unclear. Additionally, the review explores Merlin\'s role in embryogenesis, highlighting the severe developmental defects and embryonic lethality caused by NF2 deficiency. The potential therapeutic strategies targeting these genetic aberrations are also discussed, emphasizing inhibitors of mTOR, HDAC, and VEGF as promising avenues for treatment. This synthesis of current knowledge underscores the necessity for ongoing research to elucidate the detailed mechanisms of NF2/Merlin and develop effective therapeutic strategies, ultimately aiming to improve the prognosis and quality of life for individuals with NF2 mutations.

BACKGROUND: Programmed death-ligand 1 (PD-L1) expression is an immune evasion mechanism that has been demonstrated in many tumors and is commonly associated with a poor prognosis. Over the years, anti-PD-L1 agents have gained attention as novel anticancer therapeutics that induce durable tumor regression in numerous malignancies. They may be a new treatment choice for neurofibromatosis type 2 (NF2) patients.
OBJECTIVE: The aims of this study were to detect the expression of PD-L1 in NF2-associated meningiomas, explore the effect of PD-L1 downregulation on tumor cell characteristics and T-cell functions, and investigate the possible pathways that regulate PD-L1 expression to further dissect the possible mechanism of immune suppression in NF2 tumors and to provide new treatment options for NF2 patients.
RESULTS: PD-L1 is heterogeneously expressed in NF2-associated meningiomas. After PD-L1 knockdown in NF2-associated meningioma cells, tumor cell proliferation was significantly inhibited, and the apoptosis rate was elevated. When T cells were cocultured with siPD-L1-transfected NF2-associated meningioma cells, the expression of CD69 on both CD4+ and CD8+ T cells was partly reversed, and the capacity of CD8+ T cells to kill siPD-L1-transfected tumor cells was partly restored. Results also showed that the PI3K-AKT-mTOR pathway regulates PD-L1 expression, and the mTOR inhibitor rapamycin rapidly and persistently suppresses PD-L1 expression. In vivo experimental results suggested that anti-PD-L1 antibody may have a synergetic effect with the mTOR inhibitor in reducing tumor cell proliferation and that reduced PD-L1 expression could contribute to antitumor efficacy.
CONCLUSIONS: Targeting PD-L1 could be helpful for restoring the function of tumor-infiltrating lymphocytes and inducing apoptosis to inhibit tumor proliferation in NF2-associated meningiomas. Dissecting the mechanisms of the PD-L1-driven tumorigenesis of NF2-associated meningioma will help to improve our understanding of the mechanisms underlying tumor progression and could facilitate further refinement of current therapies to improve the treatment of NF2 patients.

听觉脑干植入（auditory brainstem implant，ABI）是耳蜗和蜗神经病变而无法接受人工耳蜗植入的重度和极重度感音神经性聋患者重建听觉的唯一有效疗法。近年来，ABI逐渐成为一种安全有效的技术。本文就ABI的发展史、应用现状、影响疗效的因素、局限性以及发展前景等方面进行概述。.

UNASSIGNED: NF2-schwannomatosis (NF2) is an autosomal dominant disorder prone to hearing loss. Auditory brainstem implants (ABIs) offer a promising solution for hearing rehabilitation in NF2.
UNASSIGNED: To synthesize existing literature on ABI implantation in NF2, focusing on audiological outcomes and ABI-related complications.
UNASSIGNED: The systematic review followed PRISMA guidelines and was registered in the PROSPERO database (CRD42022362155). Relevant studies were identified by searching PubMed, EMBASE, CENTRAL, CMB, and CNKI from inception to August 2023. Data on environmental sound discrimination, open-set discrimination, closed-set discrimination, and ABI-related complications were extracted and subjected to meta-analysis. Publication bias was evaluated using funnel plots and Egger\'s test.
UNASSIGNED: Thirty-three studies were included. The pooled estimate was 58% (95% CI 49-66%) for environmental sound discrimination and 55% (95% CI 40-69%) for closed-set discrimination. Regarding open-set discrimination, the pooled estimates were 30% (95% CI 19-42%) for sound only, 46% (95% CI 37-54%) for lip-reading only, and 63% (95% CI 55-70%) for sound plus lip-reading. The pooled occurrence of ABI-related complications was 33% (95% CI 15-52%).
UNASSIGNED: This meta-analysis underscores the effectiveness and safety of ABIs in NF2, providing valuable insights for evidence-based decision-making and hearing rehabilitation strategies.

Neurofibromatosis type 2 (NF2)-related vestibular schwannoma (NF2-VS) is a rare genetic disorder that results in bilateral acoustic neuromas. However, the exact pathogenesis of the disease is still unclear. This study aims to use bioinformatics analyses to identify potential hub genes and therapeutic. We retrieved the mRNA expression profiles (GSE108524 and GSE141801) of NF2-VS from the database, and selected the leading 25% genes with the most variance across samples for weighted correlation network analysis. Subsequently, we conducted gene ontology term and Kyoto Encyclopedia of Genes and Genomes signaling network enrichment analyses. The STRING database was employed for protein-protein interaction (PPI) axis construction. The mRNA-miRNA modulatory network was generated via the miRTarBase database. Differentially expressed genes (DEGs) were identified via the R package \"limma\" in both datasets, and hub genes were screened via intersection of common DEGs, candidate hub genes from the PPI axis, and candidate hub genes from the key module. Finally, common DEGs were uploaded onto the connectivity map database to determine drug candidates. Based on our observations, the blue module exhibited the most significant relation to NF2-VS, and it included the NF2 gene. Using enrichment analysis, we demonstrated that the blue modules were intricately linked to modulations of cell proliferation, migration, adhesion, junction, and actin skeleton. Overall, 356 common DEGs were screened in both datasets, and 33 genes carrying a degree > 15 were chosen as candidate hub genes in the PPI axis. Subsequently, 4 genes, namely, GLUL, CAV1, MYH11, and CCND1 were recognized as real hub genes. In addition, 10 drugs with enrichment scores < -0.7 were identified as drug candidates. Our conclusions offered a novel insight into the potential underlying mechanisms behind NF2-VS. These findings may facilitate the identification of novel therapeutic targets in the future.

OBJECTIVE: To report on a rare case of Neurofibromatosis type 2 (NF2) manifesting as oculomotor nerve palsy and explore its genetic basis.
METHODS: A patient with NF2 who had presented at Beijing Ditan Hospital Affiliated to Capital Medical University on July 10, 2021 was selected as the study subject. Cranial and spinal cord magnetic resonance imaging (MRI) was carried out on the patient and his parents. Peripheral blood samples were collected and subjected to whole exome sequencing. Candidate variant was verified by Sanger sequencing.
RESULTS: MRI revealed bilateral vestibular Schwannomas, bilateral cavernous sinus meningiomas, popliteal neurogenic tumors, and multiple subcutaneous nodules in the patient. DNA sequencing revealed that he has harbored a de novo nonsense variant of the NF2 gene, namely c.757A>T, which has replaced a codon (AAG) encoding lysine (K) at position 253 with a stop codon (TAG). This has resulted in removal of the Merlin protein encoded by the NF2 gene from position 253 onwards. The variant was not found in public databases. Bioinformatic analysis suggested that the corresponding amino acid is highly conserved. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was rated as pathogenic (PVS1+PS2+PM2_Supporting+PP3+PP4).
CONCLUSIONS: The heterozygous nonsense variant c.757A>T (p.K253*) of the NF2 gene probably underlay the disease in this patient with an early onset, atypical but severe phenotype.

Neurofibromatosis type 2 (NF2) loss occurs in approximately 30% to 50% of diffuse pleural mesothelioma (DPM) with accumulation of yes-associated protein (YAP) 1 and transcriptional coactivator with PDZ-binding motif (TAZ) in tumor nuclei. NF2 and YAP/TAZ represent potential therapeutic targets. We investigated the performance of NF2-YAP/TAZ dual immunohistochemistry (IHC) in identifying DPM that harbors NF2 alterations and in distinguishing DPM from benign mesothelial proliferations. NF2-YAP/TAZ IHC was subsequently performed in a Discovery cohort of DPMs with (n = 10) or without (n = 10) NF2 alterations detected by next-generation sequencing (NGS) and 9 benign cases. The cutoff values for loss of NF2 expression and YAP/TAZ overexpression using IHC were determined in the Discovery cohort. The performance characteristics of NF2-YAP/TAZ IHC were investigated in a Validation cohort (20 DPMs and 10 benign cases). In the Discovery cohort, all DPMs with NF2 alterations using NGS showed NF2 IHC scores of <2, whereas all NF2-wild-type DPMs showed scores of ≥2. NF2-altered DPMs had significantly higher YAP/TAZ H-scores (P < .001) than NF2-wild-type DPM and benign pleura (median H-scores: 237.5 [range, 185-275], 130.0 [range, 40-225], and 10.0 [range, 0-75], respectively). NF2-YAP/TAZ IHC demonstrated 95.2% sensitivity, 100% specificity, 100% positive predictive value, and 95% negative predictive value for detecting NF2 alterations in DPM (n = 40) with NGS as the gold standard and 87.5% sensitivity and 100% specificity for distinguishing DPM (n = 40) from benign mesothelial proliferations (n = 19). NF2-YAP/TAZ IHC has a high sensitivity and specificity for detecting NF2 alterations in DPM and a high specificity for malignancy, highlighting potential utility for guiding NF2-targeted therapies and distinguishing DPM from benign mimics.

Patients with neurofibromatosis type II (NF2) usually require surgical treatment, but the probability of tumor recurrence remains high after surgical resection. Moreover, because most of NF2 lesions involve the facial nerve, the risk of facial nerve injury during the surgery is high. Stereotactic radiotherapy can be used to treat some cases of NF2. However, it is not recommended for treatment of multiple or large tumors, and surgical resection may be more difficult after radiotherapy. Few systemic treatments are available. At present, bevacizumab is considered the first-line drug treatment for fast-growing NF2. However, bevacizumab requires long-term administration, and tumor growth will resume after drug withdrawal. Here, we present a case of NF2 that developed exacerbations after multiple treatments with gamma knife and surgery, and achieved good results after later treatment with anlotinib. Accordingly, we propose that anlotinib may be a valuable treatment option for NF2.

BACKGROUND: Pediatric meningiomas (PMs) are rare tumors; they differ from their adult counterparts by their atypicality of location, higher rates of malignant change, male preponderance, recurrence, and sometimes, their association with neurofibromatosis. This case series analyzes the clinical behavior, pathological presentation, location, and its association with neurofibromatosis type 2 (NF2).
METHODS: This case series consists of pediatric patients between the ages of 4 and 16 years who were hospitalized in the neurosurgical department of our hospital from 2012 to 2021 with different neurological symptoms and a literature review using the PubMed/MEDLINE database.
RESULTS: Sixty percent of the patients were males, while 40% were females. The most common neurological manifestations were signs of increased intracranial pressure. NF2 was absent in all patients. The predominant histopathology subtypes are atypical and WHO grade II, representing 30% and 40%, respectively.
CONCLUSIONS: This study supports the relationship between NF2 and pediatric cerebral meningioma but at a lower concomitant rate from 0 to 13%, taking into consideration our original data and the literature review, contrasting some reported cases, which suggest rates as high as 33%, 50%, and 100% in a very small number of patients. Gross total resection without postoperative radiation therapy for nonmalignant and non-NF2-associated PM proved to be a sufficient and a good treatment option.

Objective: To explore the clinical features and treatment strategy of rare tumor in the internal auditory canal(IAC). Methods: A retrospective study was carried out in 213 patients with lesion of ICA form January 2010 to December 2020. According to imaging features, surgical findings, and pathological diagnosis, there were 7 cases of non-sporadic acoustic neuroma, including 2 cases of cavernous hemangioma, 2 cases of aneurysm, 1 case of intralabyrinthical schwannoma, 1 case of meningioma, and 1 case of unilateral neurofibromatosis type 2 (NF2). The clinical manifestations, imaging data and intraoperative conditions as well as the formulation of individualized treatment strategies and prognosis were comprehensively analyzed. Results: In addition to hearing loss, cavernous hemangioma early appeared damage of facial nerve. CT showed expansion and calcification of IAC. Patients with aneurysm appeared tinnitus and vertigo early. CT showed enlargement of ampulla shape of IAC. DSA or MRA can help confirm the diagnosis. Patients with intralabyrinthine schwannoma early appeared refractory vertigo. High resolution MRI was helpful for diagnosis. \"Dural tail sign\" can be seen on enhanced MRI of meningeoma. Neurofibromatosis type 2 usually presented as bilateral vestibular schwannomas,but a few patients presented only with unilateral vestibular schwannomas.. All patients underwent labyrinth approach resection except one patient with NF2 for followed-up. Their postoperative symptoms were relieved. No tumor recurrence was observed during 6-3 years of follow-up. Conclusions: The clinical and imaging manifestations of rare tumors of the internal auditory canal are different. The principle of treatment is also different. It is helpful to avoid the serious consequences caused by blind operation to confirm diagnosis before operation.
目的： 探讨内听道少见肿瘤的临床特征及治疗策略。 方法： 收集2010年1月至2020年12月武汉大学人民医院收治的213例内听道肿瘤的临床资料，依据影像学、术中所见及病理检查，共发现内听道少见肿瘤7例，其中海绵状血管瘤2例，内听道小脑前下动脉瘤2例，迷路内神经鞘瘤1例，脑膜瘤1例，单侧神经纤维瘤病Ⅱ型（neurofibromatosis type 2，NF2）1例。综合分析其临床表现、影像学资料、治疗措施及预后。 结果： 除听力下降外，海绵状血管瘤早期即出现面神经麻痹，CT上多可见内听道扩大、点状钙化；动脉瘤早期出现耳鸣、眩晕，CT上可见内听道“壶腹样”扩大，数字减影血管造影（DSA）或磁共振血管造影（MRA）有助于确诊；迷路内神经鞘瘤早期常出现难治性眩晕，高分辨率MRI有助于确诊；脑膜瘤增强MRI上可见“脑膜尾征”；神经纤维瘤病2型多为双侧前庭神经鞘瘤，有少数患者仅表现为单侧前庭神经鞘瘤。除1例NF2患者随访观察外，其余患者均行迷路入路病变切除，术后症状均有缓解。随访6个月~3年，未见肿瘤复发。 结论： 内听道少见肿瘤的临床症状和影像学表现各有特点，治疗原则也各不相同，术前明确诊断能够避免盲目手术造成的不良后果。.