Identification of a novel form of caspase-independent cell death triggered by BH3-mimetics in diffuse large B-cell lymphoma cell lines.

BH3-mimetics represent promising anti-cancer agents in tumors that rely on the anti-apoptotic function of B-Cell Lymphoma 2 (BCL2) proteins, particularly in leukemia and lymphoma cells primed for apoptosis. Mechanistically, BH3-mimetics may displace pro-apoptotic binding partners thus inducing BAX/BAK-mediated mitochondrial permeabilization followed by cytochrome c release, activation of the caspase cascade and apoptosis. Here, we describe a novel mode of caspase-independent cell death (CICD) induced by BH3-mimetics in a subset of diffuse large B-cell lymphoma (DLBCL) cells. Of note, rather than occurring via necroptosis, CICD induced immediately after mitochondrial permeabilization was associated with transcriptional reprogramming mediated by activation of c-Jun N-terminal Kinase (JNK) signaling and Activator Protein 1 (AP1). Thereby, CICD resulted in the JNK/AP1-mediated upregulation of inflammatory chemokines and increased migration of cytotoxic Natural Killer (NK) cells. Taken together, our study describes a novel mode of CICD triggered by BH3-mimetics that may alter the immune response towards dying cells.

Acyclic Boryl Complexes of Copper(I).

Reaction of (6-Dipp)CuOtBu (6-Dipp=C{NDippCH2 }2 CH2 , Dipp=2,6-iPr2 C6 H3 ) with B2 (OMe)4 provided access to (6-Dipp)CuB(OMe)2 via σ-bond metathesis. (6-Dipp)CuB(OMe)2 was characterised by NMR spectroscopy and X-ray crystallography and shown to be a monomeric acyclic boryl of copper. (6-Dipp)CuB(OMe)2 reacted with ethylene and diphenylacetylene to provide insertion compounds into the Cu-B bond which were characterised by NMR spectroscopy in both cases and X-ray crystallography in the latter. It was also competent in the rapid catalytic deoxygenation of CO2 in the presence of excess B2 (OMe)4 . Alongside π-insertion, (6-Dipp)CuB(OMe)2 reacted with LiNMe2 to provide a salt metathesis reaction at boron, giving (6-Dipp)CuB(OMe)NMe2 , a second monomeric acyclic boryl, which also cuproborated diphenylacetylene. Computational interrogation validated these acyclic boryl species to be electronically similar to (6-Dipp)CuBpin.

Computational modeling of DLBCL predicts response to BH3-mimetics.

In healthy cells, pro- and anti-apoptotic BCL2 family and BH3-only proteins are expressed in a delicate equilibrium. In contrast, this homeostasis is frequently perturbed in cancer cells due to the overexpression of anti-apoptotic BCL2 family proteins. Variability in the expression and sequestration of these proteins in Diffuse Large B cell Lymphoma (DLBCL) likely contributes to variability in response to BH3-mimetics. Successful deployment of BH3-mimetics in DLBCL requires reliable predictions of which lymphoma cells will respond. Here we show that a computational systems biology approach enables accurate prediction of the sensitivity of DLBCL cells to BH3-mimetics. We found that fractional killing of DLBCL, can be explained by cell-to-cell variability in the molecular abundances of signaling proteins. Importantly, by combining protein interaction data with a knowledge of genetic lesions in DLBCL cells, our in silico models accurately predict in vitro response to BH3-mimetics. Furthermore, through virtual DLBCL cells we predict synergistic combinations of BH3-mimetics, which we then experimentally validated. These results show that computational systems biology models of apoptotic signaling, when constrained by experimental data, can facilitate the rational assignment of efficacious targeted inhibitors in B cell malignancies, paving the way for development of more personalized approaches to treatment.

Rhinologist Use of Antibiotics With Nasal Packing for Epistaxis.

BACKGROUND: There is limited evidence supporting the usage of prophylactic antibiotics in the setting of nasal packing for epistaxis. It is unclear what current antiobiotic usage patterns are by otolaryngologists. OBJECTIVES: Characterize the antibiotic prescribing practices employed by otolaryngologists in the management of epistaxis patients treated with packing as well as the underlying rationale. Explore the impact of experience, geography, and academic affiliation on treatment decisions. METHODS: An anonymous survey of antibiotic prescribing patterns for patients with epistaxis requiring nasal packing was distributed to all physician members of the American Rhinologic Society. Responses to each question were descriptively summarized including 95% confidence intervals and were linked to demographics using Fisher's exact tests. RESULTS: One thousand one hundred and thirteen surveys were distributed with 307 responses (27.6%). Antibiotic prescription rates varied based on packing type, with 20.0% prescribing antibiotics for dissolvable packing compared to 84.2% to 84.6% for nondissolvable packing. The absorbance of nondissolvable packing does not impact the decision to prescribe antibiotics (P > .999). Precisely 69.7% (95% CI: 64.0%-74.8%) stop antibiotics immediately following packing removal. Precisely 85.6% (95% CI: 81.6%-89.9%) cite the risk of toxic shock syndrome (TSS) when prescribing antibiotics. Notable regional differences include greater utilization of amoxicillin-clavulanate in the Midwest (67.6%) and Northeast (61.4%) as compared with the South (42.1%) and West (45.1%) (P = .013). Further, years in practice were positively associated with several patterns including prescribing antibiotics for patients with dissolvable packing (P = .008), citing prevention of sinusitis as a rationale for antibiotic use (P < .001), and a higher likelihood of having treated a patient with TSS (P = .002). CONCLUSIONS: Antibiotic use in patients with epistaxis controlled with nondissolvable packing is common. Treatment patterns are influenced by geography, years in practice, and practice type. LEVEL OF EVIDENCE: 4.

An acyclic aluminyl anion.

The potassium aluminyl complex K2[Al{N(Dipp)SiMe3}2]2 was synthesised via reduction of [AlI{N(Dipp)SiMe3}2] (Dipp = 2,6-i-Pr2C6H3). This represents the first example of an aluminyl anion supported by an acyclic ligand framework. Attempts to yield the same structure with a larger ligand framework, {N(Dipp)Si(i-Pr)3}, led to C-H cleavage. K2[Al{N(Dipp)SiMe3}2]2 behaves as a nucleophilic source of aluminium; reaction with an electrophilic ß-diketiminate supported magnesium(II) iodide forms a monomeric, acyclic magnesium aluminyl complex.

Specific interactions of BCL-2 family proteins mediate sensitivity to BH3-mimetics in diffuse large B-cell lymphoma.

The BCL-2-specific inhibitor, ABT-199 (venetoclax) has exhibited remarkable clinical activity in nearly all cases of chronic lymphocytic leukemia. In contrast, responses are usually much less in diffuse large B-cell lymphoma (DLBCL), despite high level expression of BCL-2 in over 40% of cases, indicating that co-expression of related anti-apoptotic BCL-2 family proteins may limit the activity of ABT-199. We have investigated the roles of BCL-2 proteins in DLBCL cells using a panel of specific BCL-2 homology 3 (BH3)-mimetics and identified subgroups of these cells that exhibited marked and specific dependency on either BCL-2, BCL-XL or MCL-1 for survival. Dependency was associated with selective sequestration of the pro-apoptotic proteins BIM, BAX and BAK by the specific anti-apoptotic BCL-2 protein which was important for cellular survival. Sensitivity to BH3-mimetics was independent of genetic alterations involving the BCL-2 family and only partially correlated with protein expression levels. Treatment with ABT-199 displaced BAX and BIM from BCL-2, subsequently leading to BAK activation and apoptosis. In contrast, apoptosis induced by inhibiting BCL-XL with A1331852 was associated with a displacement of both BAX and BAK from BCL-XL and occurred independently of BIM. Finally, the MCL-1 inhibitor S63845 induced mainly BAX-dependent apoptosis mediated by a displacement of BAK, BIM and NOXA from MCL-1. In conclusion, our study indicates that in DLBCL, the heterogeneous response to BH3-mimetics is mediated by selective interactions between BAX, BAK and anti-apoptotic BCL-2 proteins.

Diagnostic Challenges in a Case of IgG4-RD Affecting the Temporal Bone.

INTRODUCTION: Immunoglobulin G4-related disease (IgG4-RD) is a recently described fibroinflammatory condition with a characteristic histology. While IgG4-RD can affect a great variety of anatomical sites, it has been seldom described in the temporal bone. METHODS: Herein, a case IgG4-RD occurring in the temporal bone of a 35-year-old woman is reported. DISCUSSION: This case of IgG4-RD of the temporal bone proved a uniquely challenging diagnosis due to slightly atypical histology falling outside of "highly suggestive" criteria. CONCLUSIONS: We suggest that IgG4-RD remains a challenging diagnosis to reach despite increased awareness of the condition. We further suggest that clinicopathologic correlation remain the cornerstone of diagnosis as the spectrum of presentations of this newly described disease may be wider than previously anticipated.