Chemical genetic screens reveal defective lysosomal trafficking as synthetic lethal with NF1 loss.

Neurofibromatosis type 1, a genetic disorder caused by pathogenic germline variations in NF1, predisposes individuals to the development of tumors, including cutaneous and plexiform neurofibromas (CNs and PNs), optic gliomas, astrocytomas, juvenile myelomonocytic leukemia, high-grade gliomas and malignant peripheral nerve sheath tumors (MPNSTs), which are chemotherapy- and radiation-resistant sarcomas with poor survival. Loss of NF1 also occurs in sporadic tumors, such as glioblastoma (GBM), melanoma, breast, ovarian and lung cancers. We performed a high-throughput screen for compounds that were synthetic lethal with NF1 loss, which identified several leads, including the small molecule Y102. Treatment of cells with Y102 perturbed autophagy, mitophagy and lysosome positioning in NF1-deficient cells. A dual proteomics approach identified BLOC-one-related complex (BORC), which is required for lysosome positioning and trafficking, as a potential target of Y102. Knockdown of a BORC subunit using siRNA recapitulated the phenotypes observed with Y102 treatment. Our findings demonstrate that BORC might be a promising therapeutic target for NF1-deficient tumors.

Limited Nerve Regeneration across Acellular Nerve Allografts (ANAs) Coincides with Changes in Blood Vessel Morphology and the Development of a Pro-Inflammatory Microenvironment.

The use of acellular nerve allografts (ANAs) to reconstruct long nerve gaps (>3 cm) is associated with limited axon regeneration. To understand why ANA length might limit regeneration, we focused on identifying differences in the regenerative and vascular microenvironment that develop within ANAs based on their length. A rat sciatic nerve gap model was repaired with either short (2 cm) or long (4 cm) ANAs, and histomorphometry was used to measure myelinated axon regeneration and blood vessel morphology at various timepoints (2-, 4- and 8-weeks). Both groups demonstrated robust axonal regeneration within the proximal graft region, which continued across the mid-distal graft of short ANAs as time progressed. By 8 weeks, long ANAs had limited regeneration across the ANA and into the distal nerve (98 vs. 7583 axons in short ANAs). Interestingly, blood vessels within the mid-distal graft of long ANAs underwent morphological changes characteristic of an inflammatory pathology by 8 weeks post surgery. Gene expression analysis revealed an increased expression of pro-inflammatory cytokines within the mid-distal graft region of long vs. short ANAs, which coincided with pathological changes in blood vessels. Our data show evidence of limited axonal regeneration and the development of a pro-inflammatory environment within long ANAs.

Interpretation of Data from Translational Rodent Nerve Injury and Repair Models.

This article highlights the use of rodents as preclinical models to evaluate the management of nerve injuries, describing the pitfalls and value from rodent nerve injury and regeneration outcomes, as well as treatments derived from these rodent models. The anatomic structure, size, and cellular and molecular differences and similarities between rodent and human nerves are summarized. Specific examples of success and failure when assessing outcome metrics are presented for context. Evidence for translation to clinical practice includes the topics of electrical stimulation, Tacrolimus (FK506), and acellular nerve allografts.

Obesity and meningioma: a US population-based study paired with analysis of a multi-institutional cohort.

OBJECTIVE: Whether obesity is associated with meningioma and the impact of obesity by gender has been debated. The primary objective of this study was to investigate differences in BMI between male and female patients undergoing craniotomy for meningioma and compare those with patients undergoing craniotomy for other intracranial tumors. The secondary objective was to compare meningioma location and progression-free survival (PFS) between obese and nonobese patients in a multi-institutional cohort. METHODS: National data were obtained from the National Surgical Quality Improvement Program (NSQIP) database. Male and female patients were analyzed separately. Patients undergoing craniotomies for meningioma were compared with patients of the same sex undergoing craniotomies for other intracranial tumors. Institutional data from two academic centers were collected for all male and an equivalent number of female meningioma patients undergoing meningioma resection. Multivariate regression controlling for age was used to determine differences in meningioma location. Kaplan-Meier curves and log-rank tests were computed to investigate differences in PFS. RESULTS: From NSQIP, 4163 male meningioma patients were compared with 24,266 controls, and 9372 female meningioma patients were compared with 21,538 controls. Male and female patients undergoing meningioma resection were more likely to be overweight or obese compared with patients undergoing craniotomy for other tumors, with the odds ratio increasing with increasing weight class (all p < 0.0001). In the multi-institutional cohort, meningiomas were more common along the skull base in male patients (p = 0.0123), but not in female patients (p = 0.1246). There was no difference in PFS between obese and nonobese male (p = 0.4104) or female (p = 0.5504) patients. Obesity was associated with increased risk of pulmonary embolism in both male and female patients undergoing meningioma resection (p = 0.0043). CONCLUSIONS: Male and female patients undergoing meningioma resection are more likely to be obese than patients undergoing craniotomy for other intracranial tumors. Obese males are more likely to have meningiomas in the skull base compared with other locations, but this association was not found in females. There was no significant difference in PFS among obese patients. The mechanism by which obesity increases meningioma incidence remains to be determined.

A comparative analysis of IDH-mutant glioma in pediatric, young adult, and older adult patients.

BACKGROUND: The frequency and significance of IDH mutations in glioma across age groups is incompletely understood. We performed a multi-center retrospective age-stratified comparison of patients with IDH-mutant gliomas to identify age-specific differences in clinico-genomic features, treatments, and outcomes. METHODS: Clinical, histologic, and sequencing data from patients with IDH-mutant, grade 2-4 gliomas, were collected from collaborating institutions between 2013-2019. Patients were categorized as pediatric (<19y), YA (19-39y) or older adult (≥40y). Clinical presentation, treatment, histologic, and molecular features were compared across age categories using Fisher's exact test or analysis-of-variance. Cox proportional-hazards regression was used to determine association of age and other covariates with overall (OS) and progression-free survival (PFS). RESULTS: We identified a cohort of 379 patients (204 YA) with IDH-mutant glioma with clinical data. There were 155 (41%) oligodendrogliomas and 224 (59%) astrocytomas. YA showed significantly shorter PFS and shorter median time-to-malignant transformation (MT) compared to pediatric and adult groups, but no significant OS difference. Adjusting for pathology type, extent of resection, and upfront therapy in multivariable analysis, the YA group was independently prognostic of shorter PFS than pediatric and adult groups. Among astrocytomas, CDK4/6 copy number amplifications were associated with both shorter PFS and shorter OS. Among oligodendrogliomas, PIK3CA and CDKN2A/2B alterations were associated with shorter OS. CONCLUSIONS: IDH-mutant glioma YA patients had significantly shorter PFS and time to MT but did not differ in OS compared to pediatric and adult groups. Treatment approach varied significantly by patient age and warrant further study as addressable age-associated outcome drivers.