Citations

Background— Integrins are heterodimeric (α/β) membrane proteins that play fundamental roles in many biological processes, for example, cell adhesion and spreading, which are important for platelet function and hemostasis. The molecular mechanism that regulates integrin activation is not completely understood. Methods and Results— Here, we show that VPS33B, a member of the Sec1/Munc18 family, binds directly to the integrin β subunit. Overexpression of VPS33B in Chinese hamster ovary cells potentiated αIIbβ3 outside-in signaling but not inside-out signaling. Platelets, from megakaryocyte- and platelet-specific VPS33B conditional knockout mice, had normal morphology, yet their spreading on fibrinogen was impaired and they failed to support clot retraction. Platelet aggregation and ATP secretion in response to low-dose agonists were reduced in the VPS33B knockout mice. αIIbβ3-mediated endocytosis of fibrinogen was also defective. Tail bleeding times and times to occlusion in an FeCl 3 -induced thrombosis model were prolonged in the VPS33B knockout mice. Furthermore, VPS33B acted upstream of the RhoA-ROCK-MLC and Rac1-dependent pathways that lead to clot retraction and cell spreading, respectively. Conclusions— Our work demonstrates that vesicular trafficking complexes, containing VPS33B, are a novel class of modifiers of integrin function. Our data also provide insights into the molecular mechanism and treatment of arthrogryposis, renal dysfunction, and cholestasis syndrome.

PurposeTo describe how integrated gradient nonlinearity (GNL) correction can be used within noniterative partial Fourier (homodyne) and parallel (SENSE and GRAPPA) MR image reconstruction strategies, and demonstrate that performing GNL correction during, rather than after, these routines mitigates the image blurring and resolution loss caused by postreconstruction image domain based GNL correction.MethodsStarting from partial Fourier and parallel magnetic resonance imaging signal models that explicitly account for GNL, noniterative image reconstruction strategies for each accelerated acquisition technique are derived under the same core mathematical assumptions as their standard counterparts. A series of phantom and in vivo experiments on retrospectively undersampled data were performed to investigate the spatial resolution benefit of integrated GNL correction over conventional postreconstruction correction.ResultsPhantom and in vivo results demonstrate that the integrated GNL correction reduces the image blurring introduced by the conventional GNL correction, while still correcting GNL‐induced coarse‐scale geometrical distortion. Images generated from undersampled data using the proposed integrated GNL strategies offer superior depiction of fine image detail, for example, phantom resolution inserts and anatomical tissue boundaries.ConclusionNoniterative partial Fourier and parallel imaging reconstruction methods with integrated GNL correction reduce the resolution loss that occurs during conventional postreconstruction GNL correction while preserving the computational efficiency of standard reconstruction techniques. Magn Reson Med 75:2534–2544, 2016. © 2015 Wiley Periodicals, Inc.

Abstract The clinical efficacies of molecularly targeted glioblastomas therapies have been vastly disappointing. The multitudes of resistance mechanisms suggest that glioblastomas possess highly dynamic molecular circuits grounded in functional redundancy. Emerging data suggests that the expression of functionally redundant oncogenes induced similar forms of cellular stress, requiring hyper-activation of common compensatory pathways to ensure cell viability. Targeting these pathways, therefore, afford potential opportunities for tumor ablation while by-passing the redundancy of oncogenic circuitry. To explore this paradigm, we carried out a siRNA screen to identify synthetic lethal partners of the oncogenic Epidermal Growth Factor Receptor variant III (EGFRvIII) in glioblastoma cells and identified Polo-Like Kinase 1 (PLK1). Treatment using a PLK1 inhibitor, BI2536, or siRNAs induced preferential toxicity to the EGFRvIII expressing glioblastoma cells in multiple in vitro (serum and neurosphere lines) and in vivo models (heterotopic and orthotopic xenograft models). Consistent with the heightened PLK1 requirement, EGFRvIII expressing glioblastomas harbored increased levels of the p-Thr210 PLK1 (an activated form of PLK1). Inhibition of PLK1 by BI2536 treatment induced an increase in the proportion of cells that co-stained for p-Histone H3 and γH2AX foci, suggesting accumulation of mitotic DNA damage. This effect was exacerbated by EGFRvIII expression, implicating induction of mitotic DNA damage as a major contributor to the observed synthetic lethality. Consistent with this observation, EGFRvIII expression induced the formation of aberrant mitosis as well as prolonged mitotic progression. Further supporting an essential role for PLK1 in suppressing DNA damage accumulation, BI2536 treatment significantly enhanced the tumoricidal effect of the DNA damaging chemotherapy, temozolomide. Mechanistically, inhibition of PLK1 suppressed the expression of Rad51, the accumulation of pS14 Rad51 (an active form of Rad51), as well as overall homologous recombination efficiency in vitro. We validated the clinical pertinence of these results using three clinically annotated glioblastoma databases (TCGA, REMEBMRANDT, CGGA). In all three datasets, increased expression of a PLK1 signature consistently associated with increased expression of HR genes and lowered gene expression signature associated with DNA damage accumulation. Supporting our proposed paradigm, the tumoricidal effect of BI2536 was universally observed in a panel of eight murine ink4a/arf (-/-) EGFRvIII expressing glioblastoma clones that developed resistance to EGFR inhibitors by distinct and independent mechanisms. In aggregate, our results support the essential role of PLK1 in suppressing mitotic DNA damage and provide a novel framework for glioblastoma therapy. Citation Format: Ying Shen, Masayuki Nitta, Jie Li, Diahnn Futalan, Tyler Steed, Zack Taich, Jeffrey M. Treiber, Deanna Stevens, Mark A. Schroeder, Jann N. Sarkaria, Hong-Zhuan Chen, Tao Jiang, Bob S. Carter, Fumiko Esashi, Jill Wakosky, Frank Furnari, Webster K. Cavenee, Arshad Desai, Clark C. Chen. Modulation of mitotic DNA damage as a paradigm for glioblastoma therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2737. doi:10.1158/1538-7445.AM2014-2737

Abstract Background: We have previously shown in animal models that combination anti-HER2 therapy leads to complete tumor regression of HER2+ breast cancer (BC). We translated these findings in a neoadjuvant trial of 12 weeks (wks) of L+T (TBCRC006) that demonstrated a meaningful pathologic complete response (pCR) and near pCR (in ER+ tumors) in patients with locally advanced HER2+ BC. In the present trial, we sought to determine whether longer treatment would lead to a higher rate of pCR without the use of chemotherapy by converting near pCR to pCR especially in the ER+ subset. Methods: TBCRC023 (NCT00999804) is a randomized phase II trial combining a Simon Phase 2 design in the experimental arm with a pick-the-winner design, not powered for direct comparison. Women with HER2+ BC measuring 2 cm or larger were eligible and were randomized in a 1:2 ratio to 12 vs. 24 wks of L+T. Letrozole (along with ovarian suppression if premenopausal) was also administered in patients whose tumors were also ER+. Serial tumor biopsies were obtained at baseline, wk 1, wk 12, and at the time of surgery. All evaluable patients were assessed for pCR, defined as no residual invasive carcinoma in the breast. Patients did not undergo surgery, withdrew consent, or received additional neoadjuvant therapy were counted as non-responders. Results: Ninety-seven patients were enrolled (33 in 12-wk arm and 64 in 24-wk arm), of whom 95 were evaluable. Seventy seven percent of patients were white and 18% were black. Twenty percent were of Hispanic ethnicity. Median age was 51 and 55% were postmenopausal. Median tumor size was 5 cm and 65% were ER+. Study treatment was well tolerated with grade 1-2 diarrhea (24% in 12-wk arm, 31% in 24-wk arm) and grade 1-2 acneform rash (12% in 12-wk arm, 19% in 24-wk arm) being the most common toxicities. Grade 3 toxicities were uncommon and were mostly in the 24-wk arm (elevated liver function test: 9%, diarrhea 2%, mucositis 2%), while the 12-wk arm had one grade 3 anemia and the study’s only serious adverse event (acute kidney injury). There were no grade 4 toxicities. The experimental arm completed stage 2 accrual and pCR rate was numerically superior to control, entirely due to better results in ER+ (Table 1), but lower than the expected pCR rate of 36% needed in the planned analysis to conclude in favor of enhanced efficacy with extended therapy. pCR rates were also lower in the control arm than in the previous study. Table 1. pCR rates 12-week arm % (n)24-week arm % (n)ER-positive8.7% (2/23)33.2% (13/39)ER-negative20% (2/10)8.7% (2/23)Overall pCR12.2% (4/33)24.2% (15/62) Conclusions: Treatment with L+T (with endocrine therapy in ER+ tumors) for 24 weeks leads to doubling of the pCR rate in women with HER2+ breast cancer without using cytotoxic chemotherapy. This approach is effective and well tolerated and warrants study as part of a de-escalation strategy that may spare some patients the cost and toxicity of chemotherapy. Tissue obtained on this trial will provide a valuable resource to validate correlative findings from our prior studies and discover new biomarkers to help guide proper patient selection for treatment. Citation Format: Mothaffar F Rimawi, Polly A Niravath, Tao Wang, Brent Rexer, Andres Forero, Antonio C Wolff, Rita Nanda, Anna M Storniolo, Ian Krop, Matthew P Goetz, Julie R Nangia, Sao Jiralerspong, Anne C Pavlick, Carolina Gutierrez, Rachel Schiff, Susan G Hilsenbeck, C Kent Osborne. TBCRC023: A randomized multicenter phase II neoadjuvant trial of lapatinib plus trastuzumab, with endcorine therapy and without chemotherapy, for 12 vs. 24 weeks in patients with HER2 overexpressing breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr S6-02.

Abstract Introduction The semantic interoperability of electronic healthcare records (EHRs) systems is a major challenge in the medical informatics area. International initiatives pursue the use of semantically interoperable clinical models, and ontologies have frequently been used in semantic interoperability efforts. The objective of this paper is to propose a generic, ontology-based, flexible approach for supporting the automatic transformation of clinical models, which is illustrated for the transformation of Clinical Element Models (CEMs) into openEHR archetypes. Methods Our transformation method exploits the fact that the information models of the most relevant EHR specifications are available in the Web Ontology Language (OWL). The transformation approach is based on defining mappings between those ontological structures. We propose a way in which CEM entities can be transformed into openEHR by using transformation templates and OWL as common representation formalism. The transformation architecture exploits the reasoning and inferencing capabilities of OWL technologies. Results We have devised a generic, flexible approach for the transformation of clinical models, implemented for the unidirectional transformation from CEM to openEHR, a series of reusable transformation templates, a proof-of-concept implementation, and a set of openEHR archetypes that validate the methodological approach. Conclusions We have been able to transform CEM into archetypes in an automatic, flexible, reusable transformation approach that could be extended to other clinical model specifications. We exploit the potential of OWL technologies for supporting the transformation process. We believe that our approach could be useful for international efforts in the area of semantic interoperability of EHR systems.

PurposeTo describe a model‐based reconstruction strategy for routine magnetic resonance imaging that accounts for gradient nonlinearity (GNL) during rather than after transformation to the image domain, and demonstrate that this approach reduces the spatial resolution loss that occurs during strictly image‐domain GNL‐correction.MethodsAfter reviewing conventional GNL‐correction methods, we propose a generic signal model for GNL‐affected magnetic resonance imaging acquisitions, discuss how it incorporates into contemporary image reconstruction platforms, and describe efficient nonuniform fast Fourier transform‐based computational routines for these. The impact of GNL‐correction on spatial resolution by the conventional and proposed approaches is investigated on phantom data acquired at varying offsets from gradient isocenter, as well as on fully sampled and (retrospectively) undersampled in vivo acquisitions.ResultsPhantom results demonstrate that resolution loss that occurs during GNL‐correction is significantly less for the proposed strategy than for the standard approach at distances >10 cm from isocenter with a 35 cm field‐of‐view gradient coil. The in vivo results suggest that the proposed strategy better preserves fine anatomical detail than retrospective GNL‐correction while offering comparable geometric correction.ConclusionAccounting for GNL during image reconstruction allows geometric distortion to be corrected with less spatial resolution loss than is typically observed with the conventional image domain correction strategy. Magn Reson Med 74:1019–1031, 2015. © 2014 Wiley Periodicals, Inc.