Clonal ZEB1-driven mesenchymal transition promotes targetable oncologic anti-angiogenic therapy resistance.
Glioblastoma responses to bevacizumab are invariably transient with acquired resistance. We profiled paired patient specimens and bevacizumab-resistant xenograft models pre- and post-resistance towards the primary goal of identifying regulators whose targeting could prolong the therapeutic window, and the secondary goal of identifying biomarkers of therapeutic window closure. Bevacizumab-resistant patient specimens and xenografts exhibited decreased vessel density and increased hypoxia versus pre-resistance, suggesting that resistance occurs despite effective therapeutic devascularization. Microarray analysis revealed upregulated mesenchymal genes in resistant tumors correlating with bevacizumab treatment duration and causing three changes enabling resistant tumor growth in hypoxia. First, perivascular invasiveness along remaining blood vessels, which co-opts vessels in a VEGF-independent and neo-angiogenesis-independent manner, was upregulated in novel biomimetic 3D bioengineered platforms modeling the bevacizumab-resistant microenvironment. Second, tumor-initiating stem cells housed in the perivascular niche close to remaining blood vessels were enriched. Third, metabolic reprogramming assessed through real-time bioenergetic measurement and metabolomics upregulated glycolysis and suppressed oxidative phosphorylation. Single-cell sequencing of bevacizumab-resistant patient glioblastomas confirmed upregulated mesenchymal genes, particularly glycoprotein YKL-40 and transcription factor ZEB1, in later clones, implicating these changes as treatment-induced. Serum YKL-40 was elevated in bevacizumab-resistant vs. bevacizumab-naïve patients. CRISPR and pharmacologic targeting of ZEB1 with honokiol reversed the mesenchymal gene expression and associated stem cell, invasion, and metabolic changes defining resistance. Honokiol caused greater cell death in bevacizumab-resistant than bevacizumab-responsive tumor cells, with surviving cells losing mesenchymal morphology. Employing YKL-40 as a resistance biomarker and ZEB1 as a target to prevent resistance could fulfill the promise of anti-angiogenic therapy.
View details for DOI 10.1158/0008-5472.CAN-19-1305
View details for PubMedID 32041837
Trochanteric osteotomy for acetabular fracture fixation: a case series and literature review.
European journal of orthopaedic surgery & traumatology : orthopedie traumatologie
This study examined osteotomy union and heterotopic ossification (HO) after performing digastric trochanteric osteotomies during open reduction and internal fixation (ORIF) of acetabular and combined femoral head fractures. Femoral head osteonecrosis and trochanteric screw removal were secondarily assessed.Twenty-six patients treated at a Level I trauma center, from years 2003 to 2019, who received a digastric trochanteric osteotomy during acetabular and combined femoral head fracture ORIF through a posterior surgical approach were retrospectively identified. Osteotomies were fixed with two 3.5 mm cortical lag screws. Rates of osteotomy union, HO, femoral head osteonecrosis, and trochanteric screw removal were determined.All osteotomies went onto union without displacement or failure of fixation. Only three (12%) patients developed severe HO (modified-Brooker class III-IV). There were no instances of femoral head osteonecrosis and only one (7%) patient required trochanteric screw removal.The digastric trochanteric osteotomy heals reliably with low rates of severe HO, femoral head osteonecrosis, and screw removal for soft-tissue irritation. A review of the literature is presented and found comparable findings.
View details for DOI 10.1007/s00590-020-02753-9
View details for PubMedID 32743685
Is percutaneous screw fixation really superior to non-operative management after valgus-impacted femoral neck fracture: a retrospective cohort study.
European journal of orthopaedic surgery & traumatology : orthopedie traumatologie
The optimal management of valgus-impacted femoral neck fractures remains controversial. Internal fixation is associated with significant rates of re-operation, while historical non-operative management strategies consisting of prolonged bed rest also resulted in patient morbidity. Our hypothesis was that screw fixation would have comparable failure rates to non-operative treatment and immediate mobilization for valgus-impacted femoral neck fractures.Retrospective cohort at a single academic Level I trauma center of patients with valgus-impacted femoral neck fractures (AO/OTA 31-B1) treated with percutaneous screw fixation (n = 97) or non-operatively (n = 28). Operative treatment consisted of percutaneous screw fixation. Non-operative treatment consisted of early mobilization. The primary outcome was a salvage operation. Patient demographics were assessed between groups.More non-operatively treated patients were permitted unrestricted weight-bearing (WBAT; p = 0.002). There was no increase in complication rates or mortality, and return to previous ambulatory status was comparable between operatively and non-operatively treated patients. 35.7% (10/28) of non-operatively treated patients underwent a subsequent operation, compared to 15.5% (15/97) of patients with screw fixation (p = 0.03). Only WBAT was independently associated with treatment failure (OR 3.1, 95%CI 1.2-8.3, p =0.02). WBAT was predictive of treatment failure only in the non-operatively treated group (64.3%, 9/14 WBAT vs 8.3%, 1/12 partial, p =0.005).After controlling for weight-bearing restrictions, we found no difference in failure rates between non-operative treatment and screw fixation. Non-operative treatment with partial weight-bearing had low failure rates, comparable complication and mortality rates, and equivalent functional outcomes to operative treatment and is reasonable if a patient would like to avoid surgery and accepts the risk of subsequent arthroplasty. Overall, there were relatively high failure rates in all groups.
View details for DOI 10.1007/s00590-020-02742-y
View details for PubMedID 32710126
- Systematic Review of Cost-Effectiveness Analyses in US Spine Surgery. World neurosurgery 2020
The Path to U.S. Neurosurgical Residency for Foreign Medical Graduates: Trends from a Decade 2007-2017.
The increasing competitiveness of the neurosurgical residency match has made it progressively difficult for foreign medical graduates (FMGs) to match in neurosurgery. We compared FMG to US medical graduate (USMG) match rates in neurosurgery and identified factors associated with match outcomes for FMG in neurosurgery.Retrospective review of AANS membership data and AAMC Charting the Outcomes match reports (2007-2017).Across 1,857 neurosurgical residents (USMG:91.1%, FMG:8.9%), average FMG match rates were 24% (range 15-35%) versus 83% (range 75-94%, p<0.001) for USMG. FMG were more male (89.5% vs. 82.0%, p=0.016), older (33.9 vs 31.8-years, p=0.008), and more likely to take research year(s) before matching (95.8% vs 78.5%, p<0.001). FMGs had greater publications (5 vs 2, p<0.001) and h-indices (3 vs 1, p<0.001). The number of matched USMGs increased by 3.3 annually, whereas that of matched FMG remained unchanged (β=0.07). Compared to USMGs, FMGs were less likely to match to NIH-Top 40 (32.7% vs. 47.5%, p<0.001) and Doximity-Top 20 (20.0% vs. 29.0%, p=0.014) programs. FMGs with prior U.S. neurosurgery program affiliation were more likely to match at NIH- and Doximity-Top 20 programs (p<0.05). For NIH-programs, FMGs were older (35.3 vs. 32.0, p=0.011), had higher h-indices (5 vs. 2, p<0.001), publications (7 vs. 2, p<0.001), and were more likely to take research year(s) (94.4% vs. 76.0%, p=0.002) than USMGs. FMGs had similar patterns for matching into Doximity-Top 20 programs.While FMGs have lower match rates into US neurosurgery residencies than USMGs, several demographic, professional, and academic factors could increase the chances of successful FMG neurosurgical match.
View details for DOI 10.1016/j.wneu.2020.02.069
View details for PubMedID 32084618
The phenotypes of proliferating glioblastoma cells reside on a single axis of variation.
Although tumor-propagating cells can be derived from glioblastomas (GBMs) of the proneural and mesenchymal subtypes, a glioma stem-like cell (GSC) of the classical subtype has not been identified. It is unclear if mesenchymal GSCs (mGSCs) and/or proneural GSCs (pGSCs) alone are sufficient to generate the heterogeneity observed in GBM. We performed single-cell/nuclei RNA-sequencing of 28 gliomas, and single-cell ATAC-sequencing for 8 cases. We find that GBM GSCs reside on a single axis of variation, ranging from proneural to mesenchymal. In silico lineage tracing using both transcriptomics and genetics supports mGSCs as the progenitors of pGSCs. Dual inhibition of pGSC-enriched and mGSC-enriched growth and survival pathways provides a more complete treatment than combinations targeting one GSC phenotype alone. This study sheds light on a long-standing debate regarding lineage relationships among GSCs and presents a paradigm by which personalized combination therapies can be derived from single-cell RNA signatures, to overcome intra-tumor heterogeneity.
View details for DOI 10.1158/2159-8290.CD-19-0329
View details for PubMedID 31554641
The neurosurgery applicant's "arms race": analysis of medical student publication in the Neurosurgery Residency Match.
Journal of neurosurgery
Neurosurgery is consistently one of the most competitive specialties for resident applicants. The emphasis on research in neurosurgery has led to an increasing number of publications by applicants seeking a successful residency match. The authors sought to produce a comprehensive analysis of research produced by neurosurgical applicants and to establish baseline data of neurosurgery applicant research productivity given the increased emphasis on research output for successful residency match.A retrospective review of publication volume for all neurosurgery interns in 2009, 2011, 2014, 2016, and 2018 was performed using PubMed and Google Scholar. Missing data rates were 11% (2009), 9% (2011), and < 5% (all others). The National Resident Matching Program report "Charting Outcomes in the Match" (ChOM) was interrogated for total research products (i.e., abstracts, presentations, and publications). The publication rates of interns at top 40 programs, students from top 20 medical schools, MD/PhD applicants, and applicants based on location of residency program and medical school were compared statistically against all others.Total publications per neurosurgery intern (mean ± SD) based on PubMed and Google Scholar were 5.5 ± 0.6 in 2018 (1.7 ± 0.3, 2009; 2.1 ± 0.3, 2011; 2.6 ± 0.4, 2014; 3.8 ± 0.4, 2016), compared to 18.3 research products based on ChOM. In 2018, the mean numbers of publications were as follows: neurosurgery-specific publications per intern, 4.3 ± 0.6; first/last author publications, 2.1 ± 0.3; neurosurgical first/last author publications, 1.6 ± 0.2; basic science publications, 1.5 ± 0.2; and clinical research publications, 4.0 ± 0.5. Mean publication numbers among interns at top 40 programs were significantly higher than those of all other programs in every category (p < 0.001). Except for mean number of basic science publications (p = 0.1), the mean number of publications was higher for interns who attended a top 20 medical school than for those who did not (p < 0.05). Applicants with PhD degrees produced statistically more research in all categories (p < 0.05) except neurosurgery-specific (p = 0.07) and clinical research (p = 0.3). While there was no statistical difference in publication volume based on the geographical location of the residency program, students from medical schools in the Western US produced more research than all other regions (p < 0.01). Finally, research productivity did not correlate with likelihood of medical students staying at their home institution for residency.The authors found that the temporal trend toward increased total research products over time in neurosurgery applicants was driven mostly by increased nonindexed research (abstracts, presentations, chapters) rather than by increased peer-reviewed publications. While we also identified applicant-specific factors (MD/PhDs and applicants from the Western US) and an outcome (matching at research-focused institutions) associated with increased applicant publications, further work will be needed to determine the emphasis that programs and applicants will need to place on these publications.
View details for DOI 10.3171/2019.8.JNS191256
View details for PubMedID 31675693
Insurance type impacts the economic burden and survival of patients with newly diagnosed glioblastoma.
Journal of neurosurgery
Glioblastoma (GBM) carries a high economic burden for patients and caregivers, much of which is associated with initial surgery. The authors investigated the impact of insurance status on the inpatient hospital costs of surgery for patients with GBM.The authors conducted a retrospective review of patients with GBM (2010-2015) undergoing their first resection at the University of California, San Francisco, and corresponding inpatient hospital costs.Of 227 patients with GBM (median age 62 years, 37.9% females), 31 (13.7%) had Medicaid, 94 (41.4%) had Medicare, and 102 (44.9%) had private insurance. Medicaid patients had 30% higher overall hospital costs for surgery compared to non-Medicaid patients ($50,285 vs $38,779, p = 0.01). Medicaid patients had higher intensive care unit (ICU; p < 0.01), operating room (p < 0.03), imaging (p < 0.001), room and board (p < 0001), and pharmacy (p < 0.02) costs versus non-Medicaid patients. Medicaid patients had significantly longer overall and ICU lengths of stay (6.9 and 2.6 days) versus Medicare (4.0 and 1.5 days) and privately insured patients (3.9 and 1.8 days, p < 0.01). Medicaid patients had similar comorbidity rates to Medicare patients (67.8% vs 68.1%), and both groups had higher comorbidity rates than privately insured patients (37.3%, p < 0.0001). Only 67.7% of Medicaid patients had primary care providers (PCPs) versus 91.5% of Medicare and 86.3% of privately insured patients (p = 0.009) at the time of presentation. Tumor diameter at diagnosis was largest for Medicaid (4.7 cm) versus Medicare (4.1 cm) and privately insured patients (4.2 cm, p = 0.03). Preoperative (70 vs 90, p = 0.02) and postoperative (80 vs 90, p = 0.03) Karnofsky Performance Scale (KPS) scores were lowest for Medicaid versus non-Medicaid patients, while in subgroup analysis, postoperative KPS score was lowest for Medicaid patients (80, vs 90 for Medicare and 90 for private insurance; p = 0.03). Medicaid patients had significantly shorter median overall survival (10.7 months vs 12.8 months for Medicare and 15.8 months for private insurance; p = 0.02). Quality-adjusted life year (QALY) scores were 0.66 and 1.05 for Medicaid and non-Medicaid patients, respectively (p = 0.036). The incremental cost per QALY was $29,963 lower for the non-Medicaid cohort.Patients with GBMs and Medicaid have higher surgical costs, longer lengths of stay, poorer survival, and lower QALY scores. This study indicates that these patients lack PCPs, have more comorbidities, and present later in the disease course with larger tumors; these factors may drive the poorer postoperative function and greater consumption of hospital resources that were identified. Given limited resources and rising healthcare costs, factors such as access to PCPs, equitable adjuvant therapy, and early screening/diagnosis of disease need to be improved in order to improve prognosis and reduce hospital costs for patients with GBM.
View details for DOI 10.3171/2019.3.JNS182629
View details for PubMedID 31226687
Stress Granule Assembly Disrupts Nucleocytoplasmic Transport
2018; 173 (4): 958-+
Defects in nucleocytoplasmic transport have been identified as a key pathogenic event in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) mediated by a GGGGCC hexanucleotide repeat expansion in C9ORF72, the most common genetic cause of ALS/FTD. Furthermore, nucleocytoplasmic transport disruption has also been implicated in other neurodegenerative diseases with protein aggregation, suggesting a shared mechanism by which protein stress disrupts nucleocytoplasmic transport. Here, we show that cellular stress disrupts nucleocytoplasmic transport by localizing critical nucleocytoplasmic transport factors into stress granules, RNA/protein complexes that play a crucial role in ALS pathogenesis. Importantly, inhibiting stress granule assembly, such as by knocking down Ataxin-2, suppresses nucleocytoplasmic transport defects as well as neurodegeneration in C9ORF72-mediated ALS/FTD. Our findings identify a link between stress granule assembly and nucleocytoplasmic transport, two fundamental cellular processes implicated in the pathogenesis of C9ORF72-mediated ALS/FTD and other neurodegenerative diseases.
View details for PubMedID 29628143
Mutant Huntingtin Disrupts the Nuclear Pore Complex
2017; 94 (1): 93-+
Huntington's disease (HD) is caused by an expanded CAG repeat in the Huntingtin (HTT) gene. The mechanism(s) by which mutant HTT (mHTT) causes disease is unclear. Nucleocytoplasmic transport, the trafficking of macromolecules between the nucleus and cytoplasm, is tightly regulated by nuclear pore complexes (NPCs) made up of nucleoporins (NUPs). Previous studies offered clues that mHTT may disrupt nucleocytoplasmic transport and a mutation of an NUP can cause HD-like pathology. Therefore, we evaluated the NPC and nucleocytoplasmic transport in multiple models of HD, including mouse and fly models, neurons transfected with mHTT, HD iPSC-derived neurons, and human HD brain regions. These studies revealed severe mislocalization and aggregation of NUPs and defective nucleocytoplasmic transport. HD repeat-associated non-ATG (RAN) translation proteins also disrupted nucleocytoplasmic transport. Additionally, overexpression of NUPs and treatment with drugs that prevent aberrant NUP biology also mitigated this transport defect and neurotoxicity, providing future novel therapy targets.
View details for DOI 10.1016/j.neuron.2017.03.023
View details for Web of Science ID 000398262000012
View details for PubMedID 28384479
View details for PubMedCentralID PMC5595097