An inducible Cd79b mutation confers ibrutinib sensitivity in mouse models of Myd88-driven diffuse large B-cell lymphoma.

ABSTRACT: Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive lymphoma and constitutes a highly heterogenous disease. Recent comprehensive genomic profiling revealed the identity of numerous molecularly defined DLBCL subtypes, including a cluster which is characterized by recurrent aberrations in MYD88, CD79B, and BCL2, as well as various lesions promoting a block in plasma cell differentiation, including PRDM1, TBL1XR1, and SPIB. Here, we generated a series of autochthonous mouse models to mimic this DLBCL cluster and specifically focused on the impact of Cd79b mutations in this setting. We show that canonical Cd79b immunoreceptor tyrosine-based activation motif (ITAM) mutations do not accelerate Myd88- and BCL2-driven lymphomagenesis. Cd79b-mutant murine DLBCL were enriched for IgM surface expression, reminiscent of their human counterparts. Moreover, Cd79b-mutant lymphomas displayed a robust formation of cytoplasmic signaling complexes involving MYD88, CD79B, MALT1, and BTK. These complexes were disrupted upon pharmacological BTK inhibition. The BTK inhibitor-mediated disruption of these signaling complexes translated into a selective ibrutinib sensitivity of lymphomas harboring combined Cd79b and Myd88 mutations. Altogether, this in-depth cross-species comparison provides a framework for the development of molecularly targeted therapeutic intervention strategies in DLBCL.

Mouse models of diffuse large B cell lymphoma.

Diffuse large B cell lymphoma (DLBCL) is a genetically highly heterogeneous disease. Yet, to date, the vast majority of patients receive standardized frontline chemo-immune-therapy consisting of an anthracycline backbone. Using these regimens, approximately 65% of patients can be cured, whereas the remaining 35% of patients will face relapsed or refractory disease, which, even in the era of CAR-T cells, is difficult to treat. To systematically tackle this high medical need, it is important to design, generate and deploy suitable in vivo model systems that capture disease biology, heterogeneity and drug response. Recently published, large comprehensive genomic characterization studies, which defined molecular sub-groups of DLBCL, provide an ideal framework for the generation of autochthonous mouse models, as well as an ideal benchmark for cell line-derived or patient-derived mouse models of DLBCL. Here we discuss the current state of the art in the field of mouse modelling of human DLBCL, with a particular focus on disease biology and genetically defined molecular vulnerabilities, as well as potential targeting strategies.

Genetic Deficiency of Indoleamine 2,3-dioxygenase Aggravates Vascular but Not Liver Disease in a Nonalcoholic Steatohepatitis and Atherosclerosis Comorbidity Model.

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease that increases cardiovascular disease risk. Indoleamine 2,3-dioxygenase-1 (IDO1)-mediated tryptophan (Trp) metabolism has been proposed to play an immunomodulatory role in several diseases. The potential of IDO1 to be a link between NASH and cardiovascular disease has never been investigated. Using Apoe-/-and Apoe-/-Ido1-/- mice that were fed a high-fat, high-cholesterol diet (HFCD) to simultaneously induce NASH and atherosclerosis, we found that Ido1 deficiency significantly accelerated atherosclerosis after 7 weeks. Surprisingly, Apoe-/-Ido1-/- mice did not present a more aggressive NASH phenotype, including hepatic lipid deposition, release of liver enzymes, and histopathological parameters. As expected, a lower L-kynurenine/Trp (Kyn/Trp) ratio was found in the plasma and arteries of Apoe-/-Ido1-/- mice compared to controls. However, no difference in the hepatic Kyn/Trp ratio was found between the groups. Hepatic transcript analyses revealed that HFCD induced a temporal increase in tryptophan 2,3-dioxygenase (Tdo2) mRNA, indicating an alternative manner to maintain Trp degradation during NASH development in both Apoe-/- and Apoe-/-Ido1-/mice-. Using HepG2 hepatoma cell and THP1 macrophage cultures, we found that iron, TDO2, and Trp degradation may act as important mediators of cross-communication between hepatocytes and macrophages regulating liver inflammation. In conclusion, we show that Ido1 deficiency aggravates atherosclerosis, but not liver disease, in a newly established NASH and atherosclerosis comorbidity model. Our data indicate that the overexpression of TDO2 is an important mechanism that helps in balancing the kynurenine pathway and inflammation in the liver, but not in the artery wall, which likely determined disease outcome in these two target tissues.

Amifostine analog, DRDE-30, alleviates radiation induced lung damage by attenuating inflammation and fibrosis.

BACKGROUND: Radiotherapy of thoracic neoplasms and accidental radiation exposure often results in pneumonitis and fibrosis of lungs. Here, we investigated the potential of amifostine analogs: DRDE-07, DRDE-30, and DRDE-35, in alleviating radiation-induced lung damage. METHODS: C57BL/6 mice were exposed to 13.5 Gy thoracic irradiation, 30 min after intraperitoneal administration of the analogs, and assessed for modulation of the pathological response at 12 and 24 weeks. KEY FINDINGS: DRDE-07, DRDE-30 and DRDE-35 increased the survival of irradiated mice from 20% to 30%, 80% and 70% respectively. Reduced parenchymal opacity (X-ray CT) in the lungs of DRDE-30 pre-treated mice corroborated well with the significant decrease in Ashcroft score (p < 0.01). Two-fold increase in SOD and catalase activities (p < 0.05), coupled with a 50% increase in GSH content and a 60% decrease in MDA content (p < 0.05) suggested restoration of the antioxidant defence system. A 20% to 40% decrease in radiation-induced apoptotic and mitotic death in the lung tissue (micronuclei: p < 0.01), resulted in attenuated lung and vascular permeability (FITC-Dextran leakage) by 50% (p < 0.01), and a commensurate reduction (~50%) in leukocyte infiltration in the injured tissue (p < 0.05). DRDE-30 abrogated the activation of pro-inflammatory NF-κB and p38/MAPK signaling cascades, suppressing the release of pro-inflammatory cytokines (IL-1ß: p < 0.05; TNF-α: p < 0.05; IL-6: p < 0.05) and up-regulation of CAMs on the endothelial cell surface. Reduction in hydroxyproline content (p < 0.01) and collagen suggested inhibition of lung fibrosis which was associated with attenuation of TGF-ß/Smad pathway-mediated-EMT. CONCLUSION: DRDE-30 could be a potential prophylactic agent against radiation-induced lung injury.

Radiosensitization of calreticulin-overexpressing human glioma cell line by the polyphenolic acetate 7, 8-diacetoxy-4-methylcoumarin.

BACKGROUND: Calreticulin (CRT), an endoplasmic reticulum-resident protein generally overexpressed in cancer cells, is associated with radiation resistance. CRT shows higher transacetylase activity, as shown by us earlier, in the presence of the polyphenolic acetates (like 7, 8-diacetoxy-4-methylcoumarin, DAMC) and modifies the activity of a number of proteins, thereby influencing cell signaling. AIM: To investigate the relationship between CRT expression and radiation response in a human glioma cell line and to evaluate the radiomodifying effects of DAMC. METHODS AND RESULTS: Studies were carried out in an established human glioma cell line (BMG-1) and its isogenic clone overexpressing CRT (CROE, CRT-overexpressing cells) by analyzing clonogenic survival, cell proliferation, micronuclei analysis, and protein levels by Western blotting as parameters of responses. CRT overexpression conferred resistance against radiation-induced cell death in CROE cells (D37  = 7.35 Gy, D10  = 12.6 Gy and D0  = 7.25 Gy) as compared to BMG-1 cells (D37  = 5.70 Gy, D10  = 9.2 Gy and D0  = 5.6 Gy). A lower level of radiation-induced micronuclei formation observed in CROE cells suggested that reduced induction and/or enhanced DNA repair partly contributed to the enhanced radioresistance. Consistent with this suggestion, we noted that CRT-mediated radioresistance was coupled with enhanced grp78 level and reduced P53 activation-mediated prodeath signaling, while no changes were noted in acetylation of histone H4. DAMC-enhanced radiation-induced delayed (secondary) apoptosis, which was higher in CROE cells. CONCLUSION: CRT overexpression confers resistance against radiation-induced death of human glioma cells, which can be overcome by the polyphenolic acetate DAMC.

Disruption of GPR35 Signaling in Bone Marrow-Derived Cells Does Not Influence Vascular Inflammation and Atherosclerosis in Hyperlipidemic Mice.

G-protein-coupled receptor-35 (GPR35) has been identified as a receptor for the tryptophan metabolite kynurenic acid (KynA) and suggested to modulate macrophage polarization in metabolic tissues. Whether GPR35 can influence vascular inflammation and atherosclerosis has however never been tested. Lethally irradiated LdlrKO mice were randomized to receive GPR35KO or wild type (WT) bone marrow transplants and fed a high cholesterol diet for eight weeks to develop atherosclerosis. GPR35KO and WT chimeric mice presented no difference in the size of atherosclerotic lesions in the aortic arch (2.37 ± 0.58% vs. 1.95 ± 0.46%, respectively) or in the aortic roots (14.77 ± 3.33% vs. 11.57 ± 2.49%, respectively). In line with these data, no changes in the percentage of VCAM-1+, IAb + cells, and CD3+ T cells, as well as alpha smooth muscle cell actin expression, was observed between groups. Interestingly, the GPR35KO group presented a small but significant increase in CD68+ macrophage infiltration in the plaque. However, in vitro culture experiments using bone marrow-derived macrophages from both groups indicated that GPR35 plays no role in modulating the secretion of major inflammatory cytokines. Our study indicates that GPR35 expression does not play a direct role in macrophage activation, vascular inflammation, and the development of atherosclerosis.

Amifostine Analog, DRDE-30, Attenuates Bleomycin-Induced Pulmonary Fibrosis in Mice.

Bleomycin (BLM) is an effective curative option in the management of several malignancies including pleural effusions; but pulmonary toxicity, comprising of pneumonitis and fibrosis, poses challenge in its use as a front-line chemotherapeutic. Although Amifostine has been found to protect lungs from the toxic effects of radiation and BLM, its application is limited due to associated toxicity and unfavorable route of administration. Therefore, there is a need for selective, potent, and safe anti-fibrotic drugs. The current study was undertaken to assess the protective effects of DRDE-30, an analog of Amifostine, on BLM-induced lung injury in C57BL/6 mice. Whole body micro- computed tomography (CT) was used to non-invasively observe tissue damage, while broncheo-alveolar lavage fluid (BALF) and lung tissues were assessed for oxidative damage, inflammation and fibrosis. Changes in the lung density revealed by micro-CT suggested protection against BLM-induced lung injury by DRDE-30, which correlated well with changes in lung morphology and histopathology. DRDE-30 significantly blunted BLM-induced oxidative stress, inflammation and fibrosis in the lungs evidenced by reduced oxidative damage, endothelial barrier dysfunction, Myeloperoxidase (MPO) activity, pro-inflammatory cytokine release and protection of tissue architecture, that could be linked to enhanced anti-oxidant defense system and suppression of redox-sensitive pro-inflammatory signaling cascades. DRDE-30 decreased the BLM-induced augmentation in BALF TGF-ß and lung hydroxyproline levels, as well as reduced the expression of the mesenchymal marker α-smooth muscle actin (α-SMA), suggesting the suppression of epithelial to mesenchymal transition (EMT) as one of its anti-fibrotic effects. The results demonstrate that the Amifostine analog, DRDE-30, ameliorates the oxidative injury and lung fibrosis induced by BLM and strengthen its potential use as an adjuvant in alleviating the side effects of BLM.

Interplay Between Metabolism and Oncogenic Process: Role of microRNAs.

Cancer is a complex disease that arises from the alterations in the composition and regulation of several genes leading to the disturbances in signaling pathways, resulting in the dysregulation of cell proliferation and death as well as the ability of transformed cells to invade the host tissue and metastasize. It is increasingly becoming clear that metabolic reprograming plays a critical role in tumorigenesis and metastasis. Therefore, targeting this phenotype is considered as a promising approach for the development of therapeutics and adjuvants. The process of metabolic reprograming is linked to the activation of oncogenes and/or suppression of tumor suppressor genes, which are further regulated by microRNAs (miRNAs) that play important roles in the interplay between oncogenic process and metabolic reprograming. Looking at the advances made in the recent past, it appears that the translation of knowledge from research in the areas of metabolism, miRNA, and therapeutic response will lead to paradigm shift in the management of this disease.