Neurofibromin Research Articles

G6PD and ACSL3 are synthetic lethal partners of NF2 in Schwann cells

Neurofibromatosis Type II (NFII) is a genetic condition caused by loss of the NF2 gene, resulting in activation of the YAP/TAZ pathway and recurrent Schwann cell tumors, as well as meningiomas and ependymomas. Unfortunately, few pharmacological options are available for NFII. Here, we undertake a genome-wide CRISPR/Cas9 screen to search for synthetic-lethal genes that, when inhibited, cause death of NF2 mutant Schwann cells but not NF2 wildtype cells. We identify ACSL3 and G6PD as two synthetic-lethal partners for NF2, both involved in lipid biogenesis and cellular redox. We find that NF2 mutant Schwann cells are more oxidized than control cells, in part due to reduced expression of genes involved in NADPH generation such as ME1. Since G6PD and ME1 redundantly generate cytosolic NADPH, lack of either one is compatible with cell viability, but not down-regulation of both. Since genetic deficiency for G6PD is tolerated in the human population, G6PD could be a good pharmacological target for NFII.

NF2-Related Schwannomatosis (NF2): Molecular Insights and Therapeutic Avenues.

NF2-related schwannomatosis (NF2) is a genetic syndrome characterized by the growth of benign tumors in the nervous system, particularly bilateral vestibular schwannomas, meningiomas, and ependymomas. This review consolidates the current knowledge on NF2 syndrome, emphasizing the molecular pathology associated with the mutations in the gene of the same name, the NF2 gene, and the subsequent dysfunction of its product, the Merlin protein. Merlin, a tumor suppressor, integrates multiple signaling pathways that regulate cell contact, proliferation, and motility, thereby influencing tumor growth. The loss of Merlin disrupts these pathways, leading to tumorigenesis. We discuss the roles of another two proteins potentially associated with NF2 deficiency as well as Merlin: Yes-associated protein 1 (YAP), which may promote tumor growth, and Raf kinase inhibitory protein (RKIP), which appears to suppress tumor development. Additionally, this review discusses the efficacy of various treatments, such as molecular therapies that target specific pathways or inhibit neomorphic protein-protein interaction caused by NF2 deficiency. This overview not only expands on the fundamental understanding of NF2 pathophysiology but also explores the potential of novel therapeutic targets that affect the clinical approach to NF2 syndrome.

Acquired cystic disease associated renal cell carcinoma: A clinicopathologic and molecular study of 31 tumors

Acquired cystic disease associated renal cell carcinomas (ACD-RCC) are rare and their molecular and histopathological characteristics are still being explored. We therefore investigated the clinicopathologic and molecular characteristics of 31 tumors. The patients were predominantly male (n = 30), with tumors mainly left-sided (n = 17), unifocal (n = 19), and unilateral (n = 29) and a mean tumor size of 25 mm (range, 3–65 mm). Microscopically, several histologic patterns were present, including pure classic sieve-like (n = 4), and varied proportions of mixed classic sieve-like with papillary (n = 23), tubulocystic (n = 9), compact tubular (n = 4) and solid (n = 1) patterns. Calcium-oxalate crystals were seen in all tumors. Molecular analysis of 9 tumors using next generation sequencing showed alterations in SMARCB1 in 3 tumors (1 with frameshift deletion and 2 with copy number loss in chromosome 22 involving SMARCB1 region), however, INI1 stain was retained in all. Nonrecurrent genetic alterations in SETD2, NF1, NOTCH4, BRCA2 and CANT1 genes were also seen. Additionally, MTOR p.Pro351Ser was identified in one tumor. Copy number analysis showed gains in chromosome 16 (n = 5), 17 (n = 2) and 8 (n = 2) as well as loss in chromosome 22 (n = 2). In summary, ACD-RCC is a recognized subtype of kidney tumors, with several histological architectural patterns. Our molecular data identifies genetic alterations in chromatin modifying genes (SMARCB1 and SETD2), which may suggest a role of such genes in ACD-RCC development.

Pheochromocytoma/paraganglioma type 5 syndrome as a cause of secondary hypertension in a Colombian patient: case report

Pheochromocytoma is a tumor derived from neural crest cells able to produce sympathomimetic substances and, hence, a particular clinical picture. It is responsible for less than 1% of high blood pressure cases, with an estimated incidence between 0.4 and 0.6 cases per 100,000 people each year, and an average survival of seven years. Pheochromocytoma is a solid tumor with a high genetic component, as heritability can reach 40%. Once diagnosed, its treatment and prognosis are partly conditioned by the associated pathogenic variants that can be documented, especially those related to RET, SDHx, VHL, and NF1 genes. We present the case of a young woman with abdominal pain and high blood pressure, who was found to have a pheochromocytoma. Genetic testing detected a rare and recently discovered pathogenic variant: the SDHA:c.1A>C (p.Met1Leu). The patient responded adequately to the surgical treatment and continued the follow-up without documented recurrences. The diagnostic approach for pheochromocytoma patients must start with a clinical suspicion, followed by metabolite measurement in blood and urine, and finally, imaging. Currently, technology development allows precision medicine applicability. In this case of pheochromocytoma, recent developments in precision medicine resulted in the detection of associated genetic components involving the patient and her family. Adequate screening of the index patient is required for documenting pathogenic variants and better characterizing the disease.

The Significance of Key Proteins in the RAS Signaling Pathway: Implications for Cancer and Therapeutic Targets

The RAS signaling pathway is a crucial cell transduction pathway central to transmitting signals from outside the cell to the cell nucleus and influencing fundamental biological mechanisms like cell growth, division, and specialization. This signaling pathway has recently received much attention in scientific research because of its involvement in various diseases, especially carcinogenesis. Our study identified the significance of crucial proteins in the RAS signaling cascade in cancer development and progression. We found that proteins such as PDGFRB, PDGFB, IGF1, HRAS, HGF, FGF10, and ABL1 are involved in various types of cancer and could serve as potential therapeutic targets. Misregulation of these proteins may result in unregulated cell proliferation and contribute to cancer development and maintenance. The study also emphasizes the importance of oncogenes in cancer development, with RAS being identified as a pivotal oncogene. In addition, the findings indicate several proteins, including PDGFRA, NRAS, HRAS, CSF1R, KIT, MET, ABL1, FGFR2, FGFR3, and KRAS, function as oncogenes and are related to different forms of cancer and diseases. Targeted therapies for these proteins are being investigated in various cancer types, including gastrointestinal stromal tumors, chronic myelogenous leukemia, and bladder cancer. Moreover, we identified NF1 as a critical tumor suppressor gene essential in regulating cellular proliferation. Mutations in the NF1 gene lead to neurofibromatosis category 1. This paper emphasizes the significance of crucial proteins implicated in the RAS signaling pathway in cancer growth and advancement. Understanding the complexity of these proteins and their dysregulation could offer essential insights into the progression of practical treatment approaches that enhance and refine cancer therapies. These findings provide promising avenues for further research and advances in cancer treatment and give us hope for better outcomes in the fight against this challenging disease.

Whole-exome sequencing revealed a likely pathogenic variant in NF1 causing neurofibromatosis type I and Arrhythmogenic Cardiomyopathy

BackgroundNeurofibromatosis type I (NF1) is a genetic disorder characterized by the tumor’s development in nerve tissue. Complications of NF1 can include pigmented lesions, skin neurofibromas, and heart problems such as cardiomyopathy. In this study, we performed whole-exome sequencing (WES) on an Iranian patient with NF1 to identify the genetic cause of the disease.MethodsFollowing clinical assessment, WES was used to identify genetic variants in a family with a son suffering from NF1. No symptomatic manifestations were observed in other family members. In the studied family, in silico and segregation analysis were applied to survey candidate variants.ResultsClinical manifestations were consistent with arrhythmogenic cardiomyopathy (ACM). WES detected a likely pathogenic heterozygous missense variant, c.3277G > A:p.Val1093Met, in the NF1 gene, confirmed by PCR and Sanger sequencing. The patient’s parents and brother had a normal sequence at this locus.ConclusionsAlthough there is no cure for NF1, genetic tests, such as WES, can detect at-risk asymptomatic family members. Furthermore, cardiac evaluation could also help these patients before heart disease development.

The histone lysine acetyltransferase KAT2B inhibits cholangiocarcinoma growth: evidence for interaction with SP1 to regulate NF2-YAP signaling

BackgroundCholangiocarcinoma (CCA) is a highly malignant cancer of the biliary tract with poor prognosis. Further mechanistic insights into the molecular mechanisms of CCA are needed to develop more effective target therapy.MethodsThe expression of the histone lysine acetyltransferase KAT2B in human CCA was analyzed in human CCA tissues. CCA xenograft was developed by inoculation of human CCA cells with or without KAT2B overexpression into SCID mice. Western blotting, ChIP-qPCR, qRT-PCR, protein immunoprecipitation, GST pull-down and RNA-seq were performed to delineate KAT2B mechanisms of action in CCA.ResultsWe identified KAT2B as a frequently downregulated histone acetyltransferase in human CCA. Downregulation of KAT2B was significantly associated with CCA disease progression and poor prognosis of CCA patients. The reduction of KAT2B expression in human CCA was attributed to gene copy number loss. In experimental systems, we demonstrated that overexpression of KAT2B suppressed CCA cell proliferation and colony formation in vitro and inhibits CCA growth in mice. Mechanistically, forced overexpression of KAT2B enhanced the expression of the tumor suppressor gene NF2, which is independent of its histone acetyltransferase activity. We showed that KAT2B was recruited to the promoter region of the NF2 gene via interaction with the transcription factor SP1, which led to enhanced transcription of the NF2 gene. KAT2B-induced NF2 resulted in subsequent inhibition of YAP activity, as reflected by reduced nuclear accumulation of oncogenic YAP and inhibition of YAP downstream genes. Depletion of NF2 was able to reverse KAT2B-induced reduction of nuclear YAP and subvert KAT2B-induced inhibition of CCA cell growth.ConclusionsThis study provides the first evidence for an important tumor inhibitory effect of KAT2B in CCA through regulation of NF2-YAP signaling and suggests that this signaling cascade may be therapeutically targeted for CCA treatment.

Chromophobe Renal Cell Carcinoma With Extensive Retraction Artifact: A Potential Diagnostic Pitfall From Micropapillary Urothelial Carcinoma.

In addition to "classic" and eosinophilic subtype, chromophobe renal cell carcinoma (RCC) is well-known to demonstrate various morphological patterns including adenomatoid, microcystic, pigmented, multicystic, papillary, neuroendocrine-like, and small cell-like, all of which are important to appreciate for accurate diagnosis. Herein, we expand on a unique chromophobe RCC morphology not previously described consisting of tumor cells with extensive stromal retraction, mimicking upper urothelial tract micropapillary carcinoma (MPC). Twelve MPC-like chromophobe RCC nephrectomies were reviewed with clinicopathological features recorded; molecular testing was performed on 7 of 12 tumors. Patients were mostly men (n=10) with a mean age of 65 years. Mean tumor size was 6.4 cm with pathological stage distribution as follows: 4 (33%) T1a, 2 (17%) T1b, 1 (8%) T2b, and 3 (25%) T3a. The extent of MPC-like chromophobe RCC foci ranged from 10% to 40% (mean=26%; there was no correlation between the extent of MPC-like chromophobe RCC foci and tumor stage). Other chromophobe RCC morphological patterns were not identified. When performed, all (100%) tumors depicted prototypic chromophobe RCC staining pattern of KIT positivity/KRT7 positivity. Molecular showed 6 of 7 (86%) with multiple chromosomal losses. Clinically significant mutations were identified in NF1, TP53, FLCN (likely somatic), CHEK2, and ZFHX3 genes. Follow up available in 9 patients showed no evidence of disease (mean=23 months). Although the etiology behind the extensive stromal retraction in our tumors is unknown, this may likely be artifactual in nature. Nonetheless, it is important to include MPC-like chromophobe RCC in the spectrum of "variant" morphologies to avoid diagnostic pitfalls from micropapillary carcinoma.

Diagnostic Approaches to Investigate JAK2-Unmutated Erythrocytosis Based on a Single Tertiary Center Experience.

Erythrocytosis is attributed to various clinical and molecular factors. Many cases of JAK2-unmutated erythrocytosis remain undiagnosed. We investigated the characteristics and causes of JAK2-unmutated erythrocytosis. We assessed the clinical and laboratory results of patients with erythrocytosis without JAK2 mutations and performed targeted next-generation sequencing (NGS) panels for somatic and germline mutations. In total, 117 patients with JAK2-unmutated erythrocytosis were included. The median hemoglobin and hematocrit levels were 17.9 g/dL and 53.4%, respectively. Erythropoietin levels were not below the reference range. Thrombotic events were reported in 17 patients (14.5%). Among JAK2-unmutated patients, 44 had undergone targeted panel sequencing consisting of myeloid neoplasm-related genes, and 16 had one or more reportable variants in ASXL1 (5/44), TET2, CALR, FLT3, and SH2B3 (2/44). Additional testing for germline causes revealed eight variants in seven genes in eight patients, including NF1, BPGM, EPAS1, PIEZO1, RHAG, SH2B3, and VHL genes. One NF1 pathogenic, one BPGM likely pathogenic, and six variants of undetermined significance were detected. Somatic and germline mutations were identified in 36.4% and 33.3 % of the JAK2-unmutated group; most variants had unknown clinical significance. Not all genetic causes have been identified; comprehensive diagnostic approaches are crucial for identifying the cause of erythrocytosis.

A comprehensive histomolecular characterization of meningioangiomatosis: Further evidence for a precursor neoplastic lesion.

Meningioangiomatosis (MAM) remains a poorly understood lesion responsible for epileptic disease. In the past, MAM was primarily described in the context of neurofibromatosis type 2 before being mainly reported sporadically. Moreover, the malformative or tumoral nature is still debated. Because a subset of MAM are associated with meningiomas, some authors argue that MAM corresponds to an infiltration pattern of these tumors. For these reasons, MAM has not been added to the World Health Organization (WHO) Classification of Central Nervous System Tumors as a specific entity. In the present study, we characterized a series of pure MAM (n = 7) and MAM associated with meningiomas (n = 4) using histopathology, immunohistochemistry, genetic (fluorescent in situ and DNA sequencing analyses), and epigenetic (DNA-methylation profiling) data. We evidenced two distinct morphological patterns: MAM with a fibroblastic-like pattern having few lesional cells, and MAM with a more cellular pattern. A subset was associated with the genetic alterations previously reported in meningiomas (such as a KMT2C mutation and a hemizygous deletion of chromosome 22q including the NF2 gene). The DNA-methylation profile, using a t-distributed stochastic neighbor embedding analysis, evidenced that MAM (pure or associated with meningiomas) clustered in a separate group from pediatric meningiomas. The present results seem to suggest that MAM represents a neoplastic lesion and encourage the further study of similar additional series so that it may be included in a future WHO classification.

Abstract 3875: Glioblastoma mutational profiles drive cancer cell signaling and immune evasion

Abstract Glioblastoma multiforme (GBM) is the most common malignant brain tumor in adults with a median survival below two years. Characterization of GBM through gene expression profiling and DNA sequencing has identified disease subgroups and commonly altered genes and pathways, including alterations in the genes encoding neurofibromin-1 (NF1) and the epidermal growth factor receptor (EGFR). NF1 and EGFR are involved in receptor tyrosine kinase (RTK), RAS/MEK/ERK, and PI3K signaling, and together, are genetically altered in over 60% of adult GBMs. Interestingly, NF1 and EGFR alterations in GBM are almost always mutually exclusive. Here, we designed a multimodal approach integrating spatial proteomics, transcriptomics, and genomics to measure cell composition, immune cell function, cancer cell signaling, cellular spatial organization, gene expression, transcriptional subtypes, and genome alterations in 80 NF1 and EGFR altered human GBMs with extensively curated treatment and survival data. We quantified the spatial expression of 42 proteins in over 31 million single cells measuring RTK/RAS/PI3K and Rb signaling and features of the TME, including 23 cell types covering tumor cells, immune cells, and brain resident cells. In addition to tumor genotype labels, we classified each GBM tumor by its transcriptional subtype (i.e., mesenchymal, classical, or proneural). We identified genotype-phenotype associations in GBM including hyperactive RAS signaling cellular niches, a macrophage-rich TME, and an epithelial-mesenchymal signature in NF1 altered tumors and hyperactive RTK signaling and an immune desert TME in EGFR amplified tumors. Furthermore, we observed spatial heterogeneity in cancer cell signaling patterns suggestive of the presence of different tumor cell clones within different regions of each GBM tumor. Together, we identify several genotype-associated features of GBMs, reinforcing the value of integrating spatial multi-omic data for generation of genotype-driven therapeutic hypotheses, with implications for GBM genotype-based therapeutic stratification. Citation Format: Maryam Pourmaleki, Brian D. Greenstein, Caitlin J. Jones, Subhiksha Nandakumar, Daniel A. Navarrete, Smrutiben Mehta, Carl Campos, Travis J. Hollmann, Nicholas D. Socci, Tejus Bale, Sohrab P. Shah, Ingo K. Mellinghoff. Glioblastoma mutational profiles drive cancer cell signaling and immune evasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3875.

Abstract 4564: Therapeutic potential of SOS1 and KRAS inhibitors in malignant peripheral nerve sheath tumors

Abstract Neurofibromatosis type 1 (NF1) is a genetic disorder that affects the nervous system. It is caused by mutations in the NF1 gene. NF1 loss of function leads to elevated RAS signaling, which plays a crucial role in cell growth and proliferation. Due to the dysregulated RAS signaling, individuals with NF1 are prone to the development of neurofibromas. These neurofibromas are typically benign and called Plexiform Neurofibromas (PNFs), in some cases, they can transform into malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are highly aggressive and invasive cancers that contribute to a significant proportion of soft tissue sarcomas. The exact mechanisms behind this transformation are not fully understood, however it involves additional genetic mutations and alterations in cellular signaling pathways. With limited effective targeted therapies available, surgical removal remains the primary treatment option. However, due to tumor size and location, surgery may not always be feasible. The MEK inihibitor, selumetinib, has received approval for the treatment of PNFs, however some patients who were treated with selumetinib continued to develop MPNSTs suggesting that MEK inhibitors may have limitations in addressing MPNSTs. To target the RAS pathway and mitigate the effects of NF1 gene alterations, we aim to explore the therapeutic potential of two novel, potent and orally bioavailable small molecule inhibitors targeting SOS1 (BI 1701963) or KRAS (KRASmulti inhibitor BI 3706674), as alternative treatment options for MPNSTs. The KRASmulti inhibitor BI 3706674 binds non-covalently to the KRAS wild type allele as well as multiple KRAS mutant alleles in the GDP-bound state and thereby disrupts KRAS signaling. Therefore, we hypothesize that both inhibitors will work in NF1 models by reducing activated KRAS levels. In this study, a series of in vitro and in vivo experiments were conducted to evaluate the efficacy of BI 1701963 and BI 3706674 inhibitors, both individually and in combination. The studies were done in comparison to the MEK inhibitor selumetinib. In vitro analysis revealed a synergistic anti-proliferative effect when combining BI 1701963 and BI 3706674 inhibitors both in 2D and 3D growth conditions, which led to the downregulation of the RAS pathway, specifically the MAPK and PI3K signaling cascade, and an increase in apoptosis. The in vivo efficacy of either BI 1701963 or BI 3706674 inhibitor alone or in combination was tested in four different in vivo MPNST models. We observed significant tumor growth stabilization as well as tumor regression in all tested models in vivo. In-depth pathway modulation and pharmaco-dynamic studies are ongoing. In conclusion, this study highlights the combined effects of SOS1 (BI 1701963) and KRAS (BI 3706674) inhibition in MPNSTs. The combination therapy of these novel therapeutics may hold promise as a potential treatment strategy for patients with MPNSTs. Citation Format: Özlem Yüce Petronczki, Laura Pisarsky, Petra Lujza Szabó, Julia Brunmair, Antonia Geyer, Norbert Kraut, Darryl McConnell, Irene Waizenegger. Therapeutic potential of SOS1 and KRAS inhibitors in malignant peripheral nerve sheath tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4564.

Abstract 5048: NF2 mutations are enriched in FH deficient renal cell cancer

Abstract Introduction: NF2 is a tumor suppressor gene in charge of producing a protein called Merlin that controls cell growth and division. Mutations in the NF2 gene affect predominantly the nervous system causing the development of benign tumors. NF2 mutations have been reported in Renal cancers with morphologically specific tumor types and in aggressive tumors. We studied a cohort of 16 cases of RCC in which the NF2 mutation was identified and describe other molecular changes as well as morphology and clinic-pathological correlation. Materials and Methods: Sixteen patients had been consented and treated for renal masses in protocols of the UOB division of the NCI. Next generation sequencing was performed with tumor DNA from FFPE tissue using the Illumina TruSight Oncology 500 Kit (TSO500) NextSeq 550DX. TSO500 assay was designed to detect single nucleotide variations, small insertions/deletions, copy number variations from 92 genes, TMB and MSI. Morphology and IHC stains were performed. Results: Nine patients were female and 7 males, ranging in age from 21 to 87 years. Fourteen patients underwent partial or total nephrectomies, one case had a biopsy and in 1 case a metastatic tumor to a lymph node was studied. Morphologically, nine cases were diagnosed as HLRCC, three clear cells, two cases with clear and papillary cell, one medullary and one oncocytoma. Genetic findings revealed mutations in NF2, FH,VHL, SMARCB1, HOBB13, ARID1B, B2M, EP300, BCORL1 and MGA. Concurrent coexistence of NF2 and FH mutations was present in 9 cases. Three patients with concurrent FH and NF2 mutations died of the disease. Conclusions: NF2 mutations have been identified in a variety of morphologic types of Renal cell cancer. However, we were surprised by the number of cases with NF2 mutation in tumors that also harbor the FH (HLRCC) mutation. NF2 tumors have been reported to have an aggressive behavior, and FH cancers are also known to have poor survival. Genomic studies of renal cancers is recommended since some genetic alterations are targetable and may provide adequate therapies that will lead to longer survivals. Citation Format: Khaled Bin Satter, Liqian Xi, Christopher Rickets, William M. Linehan, Maria J. Merino. NF2 mutations are enriched in FH deficient renal cell cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5048.

Abstract 2021: The RXR agonist MSU-42011 and the MEK inhibitor selumetinib reduce pERK levels in NF1-deficient cells and inhibit cytokine production in macrophages

Abstract Neurofibromatosis type 1 (NF1) is a common genetic disease that predisposes approximately 50% of affected individuals to develop plexiform neurofibromas (PNFs), which can progress to highly aggressive malignant peripheral nerve sheath tumors (MPNSTs) in approximately 10% of patients. NF1 is caused by mutations in the tumor suppressor gene NF1, which encodes for neurofibromin, a negative regulator of RAS activity. Selumetinib, a specific inhibitor of MEK1/2, is the only FDA-approved drug for NF1-associated PNFs. However, the anti-tumor effects of selumetinib are limited in MPNSTs and have dose-limiting side effects. Deficiency of the NF1 gene not only promotes tumorigenesis but also has broad effects on the immune cells and cytokine signaling driven by hyperactive RAS signaling. Because macrophages account for almost half of cells in NF1 lesions and their infiltration correlates with disease progression, we hypothesized that targeting tumor-promoting immune cells could be an alternative approach for treating NF1. The novel retinoid X receptor (RXR) agonist MSU-42011 reduces tumor growth in experimental Kras-driven cancers by decreasing pERK expression, reducing tumor-promoting immune cells like CD206+ macrophages and regulatory T cells, and increasing activated cytotoxic T cells. Here, we treated NF1-deficient cells and macrophages with MSU-42011 and selumetinib, either alone or in combination, using monoculture and conditioned media (CM) conditions. In human PNF cells and mouse MPNSTs, treatment with 200 nM MSU-40211 or 50 nM selumetinib for 3 hours reduced pERK protein levels compared with untreated controls, and the combination treatment enhanced this reduction in pERK protein levels. Additionally, there was a trend toward reduction in cell viability with increasing drug concentrations after 72 hours of the combination treatment. Moreover, CM from human and mouse PNF cells increased the mRNA expression of monocyte chemoattractant CCL2 (C-C motif chemokine ligand 2) and the secretion of IL-6 and TNFα in human THP1 monocytes/macrophages and bone marrow derived macrophages (BMDM). Notably, MSU-42011 and selumetinib alone inhibited CCL2 mRNA expression in THP1 macrophages and BMDM stimulated with CM from human and mouse PNF cells, respectively, and the inhibition of CCL2 mRNA expression was greatest with combination treatment. The combination of MSU42011 and selumetinib also significantly reduced tumor burden in a LL2 model of lung cancer driven by an activating Kras mutation. Based on the similarities in RAS activation and immune cell infiltration in NF1 and lung cancer, our next step is to confirm the immunomodulatory and anti-tumor effects of MSU-42011 and selumetinib in a syngeneic model of PNF and MPNST. Citation Format: Pei-Yu Hung, Jessica A. Moerland, Karen T. Liby. The RXR agonist MSU-42011 and the MEK inhibitor selumetinib reduce pERK levels in NF1-deficient cells and inhibit cytokine production in macrophages [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2021.

RNA-binding proteins potentially regulate the alternative splicing of apoptotic genes during knee osteoarthritis progression

BackgroundAlternative splicing (AS) is a principal mode of genetic regulation and one of the most widely used mechanisms to generate structurally and functionally distinct mRNA and protein variants. Dysregulation of AS may result in aberrant transcription and protein products, leading to the emergence of human diseases. Although considered important for regulating gene expression, genome-wide AS dysregulation, underlying mechanisms, and clinical relevance in knee osteoarthritis (OA) remain unelucidated. Therefore, in this study, we elucidated and validated AS events and their regulatory mechanisms during OA progression.ResultsIn this study, we identified differentially expressed genes between human OA and healthy meniscus samples. Among them, the OA-associated genes were primarily enriched in biological pathways such as extracellular matrix organization and ossification. The predominant OA-associated regulated AS (RAS) events were found to be involved in apoptosis during OA development. The expression of the apoptosis-related gene BCL2L13, XAF1, and NF2 were significantly different between OA and healthy meniscus samples. The construction of a covariation network of RNA-binding proteins (RBPs) and RAS genes revealed that differentially expressed RBP genes LAMA2 and CUL4B may regulate the apoptotic genes XAF1 and BCL2L13 to undergo AS events during OA progression. Finally, RT-qPCR revealed that CUL4B expression was significantly higher in OA meniscus samples than in normal controls and that the AS ratio of XAF1 was significantly different between control and OA samples; these findings were consistent with their expected expression and regulatory relationships.ConclusionsDifferentially expressed RBPs may regulate the AS of apoptotic genes during knee OA progression. XAF1 and its regulator, CUL4B, may serve as novel biomarkers and potential therapeutic targets for this disease.

High-Grade Astrocytoma with Piloid Features: A Dual Institutional Review of Imaging Findings of a Novel Entity.

High-grade astrocytoma with piloid features (HGAP) is a recently identified brain tumor characterized by a distinct DNA methylation profile. Predominantly located in the posterior fossa of adults, HGAP is notably prevalent in individuals with neurofibromatosis type 1. We present an image-centric review of HGAP and explore the association between HGAP and neurofibromatosis type 1. Data were collected from 8 HGAP patients treated at two tertiary care institutions between January 2020 and October 2023. Demographic details, clinical records, management, and tumor molecular profiles were analyzed. Tumor characteristics, including location and imaging features on MR imaging, were reviewed. Clinical or imaging features suggestive of neurofibromatosis 1 or the presence of NF1 gene alteration were documented. The mean age at presentation was 45.5 years (male/female = 5:3). Tumors were midline, localized in the posterior fossa (n = 4), diencephalic/thalamic (n = 2), and spinal cord (n = 2). HGAP lesions were T1 hypointense, T2-hyperintense, mostly without diffusion restriction, predominantly peripheral irregular enhancement with central necrosis (n = 3) followed by mixed heterogeneous enhancement (n = 2). Two NF1 mutation carriers showed signs of neurofibromatosis type 1 before HGAP diagnosis, with one diagnosed during HGAP evaluation, strengthening the HGAP-NF1 link, particularly in patients with posterior fossa masses. All tumors were IDH1 wild-type, often with ATRX, CDKN2A/B, and NF1 gene alteration. Six patients underwent surgical resection followed by adjuvant chemoradiation. Six patients were alive, and two died during the last follow-up. Histone H3 mutations were not detected in our cohort, such as the common H3K27M typically seen in diffuse midline gliomas, linked to aggressive clinical behavior and poor prognosis. HGAP lesions may involve the brain or spine and tend to be midline or paramedian in location. Underlying neurofibromatosis type 1 diagnosis or imaging findings are important diagnostic cues.

Unilateral Multifocal Inner Ear and Internal Auditory Canal or Cerebellopontine Angle Cochleovestibular Schwannomas-Genetic Analysis and Management by Surgical Resection and Cochlear Implantation.

To describe the genetic characteristics and the management of two very rare cases of unilateral multifocal inner ear and internal auditory canal or cerebellopontine angle cochleovestibular schwannomas not being associated to full neurofibromatosis type 2-related schwannomatosis. In a 29-year-old man and a 55-year-old woman with single-sided deafness multifocal unilateral cochleovestibular schwannomas were surgically resected, and hearing was rehabilitated with a cochlear implant (CI). Unaffected tissue was analyzed using next generation sequencing of the NF2 gene. Tumor tissue was analyzed using a 340-parallel sequencing gene panel. Mutations in the NF2 gene, word recognition score for monosyllables at 65 dB SPL (WRS 65 ) with CI. No disease-causing mutation was detected in the examined sequences in blood leucokytes. All tumor samples revealed, among others, somatic pathogenic NF2 mutations. While the anatomically separate tumors in case 1 were likely molecular identical, the tumors in case 2 showed different genetic patterns. WRS 65 was 55% at 6 years of follow-up and 60% at 4.5 years of follow-up, respectively. The occurrence of multifocal unilateral cochleovestibular schwannomas without pathogenic variants in NF2 in non-affected blood leucocytes can be associated with mosaic NF2 -related schwannomatosis (case 1), or with likely sporadic mutations (case 2) and may be overlooked due to their extreme rarity. Although challenging, successful hearing rehabilitation could be achieved through surgical resection of the tumors and cochlear implantation.

Patient Sex and Origin Influence Distribution of Driver Genes and Clinical Presentation of Paraganglioma.

Sexual and ancestral differences in driver gene prevalence have been described in many cancers but have not yet been investigated in pheochromocytoma and paraganglioma (PPGL). This study aims to assess whether sex and ancestry influence prevalence of PPGL driver genes and clinical presentation. We conducted a retrospective analysis of patients with PPGL considering studies from 2010 onwards that included minimal data of type of disease, sex, mutated gene, and country of origin. Additional features were recorded when available (age, tumor location, bilateral or multifocal, somatic or germline, and metastatic disease). We included 2162 patients: 877 in Europe and 757 in Asia. Males presented more often with germline pathogenic variants (PVs) in genes activating hypoxia pathways (P = .0006) and had more often sympathetic paragangliomas (P = .0005) and metastasis (P = .0039). On the other hand, females with PPGLs due to MAX PVs were diagnosed later than males (P = .0378) and more often developed metastasis (P = .0497). European but not Asian females presented more often with PPGLs due to PVs in genes related to kinase signaling (P = .0052), particularly RET and TMEM127. Contrary to experiences from Europe, Asian patients with PPGL due to PVs in kinase signaling genes NF1, HRAS, and FGFR1 showed a high proportion of sympathetic tumors, while European patients almost exclusively had adrenal tumors (P < .005). Personalized management of patients with PPGL might benefit from considering sexual and ancestral differences. Further studies with better clinically aligned cohorts from various origins are required to better dissect ancestral influences on PPGL development.

Treatment and prognostic implications of strong PD-L1 expression in primary hepatic sarcomatoid carcinoma.

Primary hepatic sarcomatoid carcinoma (HSC) is an extremely rare and aggressive subtype of primary liver cancer. HSC has uncertain pathogenesis and dismal prognosis with overall survival of only 8.3months. The molecular alterations of HSC are also not well understood. In this study, the authors describe a patient who presented with a large liver mass. The patient underwent complete surgical resection and histological examination demonstrated HSC, infiltrating the stomach. PD-L1 was strongly positive in the tumor cells. The patient was started on anti-PD-L1 immunotherapy postsurgery and is doing well 15 months after surgical resection. Tumor whole exome sequencing revealed genetic alterations in TP53, NF2 and MAGEC3 genes, indicating their potential role in tumor development.

The serine-threonine protein kinase Snf1 orchestrates the expression of plant cell wall-degrading enzymes and is required for full virulence of the maize pathogen Colletotrichum graminicola

Colletotrichum graminicola, the causal agent of maize leaf anthracnose and stalk rot, differentiates a pressurized infection cell called an appressorium in order to invade the epidermal cell, and subsequently forms biotrophic and necrotrophic hyphae to colonize the host tissue. While the role of force in appressorial penetration is established (Bechinger et al., 1999), the involvement of cell wall-degrading enzymes (CWDEs) in this process and in tissue colonization is poorly understood, due to the enormous number and functional redundancy of these enzymes. The serine/threonine protein kinase gene SNF1 identified in Sucrose Non-Fermenting yeast mutants mediates de-repression of catabolite-repressed genes, including many genes encoding CWDEs. In this study, we identified and functionally characterized the SNF1 homolog of C. graminicola. Δsnf1 mutants showed reduced vegetative growth and asexual sporulation rates on media containing polymeric carbon sources. Microscopy revealed reduced efficacies in appressorial penetration of cuticle and epidermal cell wall, and formation of unusual medusa-like biotrophic hyphae by Δsnf1 mutants. Severe and moderate virulence reductions were observed on intact and wounded leaves, respectively. Employing RNA-sequencing we show for the first time that more than 2,500 genes are directly or indirectly controlled by Snf1 in necrotrophic hyphae of a plant pathogenic fungus, many of which encode xylan- and cellulose-degrading enzymes. The data presented show that Snf1 is a global regulator of gene expression and is required for full virulence.