Rate of CRL4(CRBN) substrate Ikaros and Aiolos degradation underlies differential activity of lenalidomide and pomalidomide in multiple myeloma cells by regulation of c-Myc and IRF4.

Recent discoveries suggest that the critical events leading to the anti-proliferative activity of the IMiD immunomodulatory agents lenalidomide and pomalidomide in multiple myeloma (MM) cells are initiated by Cereblon-dependent ubiquitination and proteasomal degradation of substrate proteins Ikaros (IKZF1) and Aiolos (IKZF3). By performing kinetic analyses, we found that the downregulation or proteasomal degradation of Ikaros and Aiolos led to specific and sequential downregulation of c-Myc followed by IRF4 and subsequent growth inhibition and apoptosis. Notably, to ensure growth inhibition and cell death, sustained downregulation of Ikaros and Aiolos, c-Myc or IRF4 expression was required.

A Dual Color Immunohistochemistry Assay for Measurement of Cereblon in Multiple Myeloma Patient Samples.

Clinical interest in the measurement of Cereblon (CRBN), the primary target of the IMiDs immunomodulatory drugs lenalidomide and pomalidomide, has been fueled by its essential requirement for antitumor or immunomodulatory activity of both drugs in multiple myeloma (MM). However, limited analyses of clinical samples for CRBN gene expression or protein levels have utilized unvalidated reagents and assays, raising uncertainty about the interpretation of these results. We previously described a highly specific rabbit monoclonal antibody CRBN65 against 65-76 AA of human Cereblon.

CC-122, a pleiotropic pathway modifier, mimics an interferon response and has antitumor activity in DLBCL.

Cereblon (CRBN), a substrate receptor of the Cullin 4 RING E3 ubiquitin ligase complex, is the target of the immunomodulatory drugs lenalidomide and pomalidomide. Recently, it was demonstrated that binding of these drugs to CRBN promotes the ubiquitination and subsequent degradation of 2 common substrates, transcription factors Aiolos and Ikaros. Here we report that CC-122, a new chemical entity termed pleiotropic pathway modifier, binds CRBN and promotes degradation of Aiolos and Ikaros in diffuse large B-cell lymphoma (DLBCL) and T cells in vitro, in vivo, and in patients, resulting in both cell autonomous as well as immunostimulatory effects.

Clinical and pharmacodynamic analysis of pomalidomide dosing strategies in myeloma: impact of immune activation and cereblon targets.

In preclinical studies, pomalidomide mediated both direct antitumor effects and immune activation by binding cereblon. However, the impact of drug-induced immune activation and cereblon/ikaros in antitumor effects of pomalidomide in vivo is unknown. Here we evaluated the clinical and pharmacodynamic effects of continuous or intermittent dosing strategies of pomalidomide/dexamethasone in lenalidomide-refractory myeloma in a randomized trial.

Measuring cereblon as a biomarker of response or resistance to lenalidomide and pomalidomide requires use of standardized reagents and understanding of gene complexity.

Cereblon, a member of the cullin 4 ring ligase complex (CRL4), is the molecular target of the immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide and is required for the antiproliferative activity of these agents in multiple myeloma (MM) and immunomodulatory activity in T cells. Cereblon's central role as a target of lenalidomide and pomalidomide suggests potential utility as a predictive biomarker of response or resistance to IMiD therapy. Our studies characterized a cereblon monoclonal antibody CRBN65, with high sensitivity and specificity in Western analysis and immunohistochemistry that is superior to commercially available antibodies.

Discovery of AC710, a Globally Selective Inhibitor of Platelet-Derived Growth Factor Receptor-Family Kinases.

A series of potent, selective platelet-derived growth factor receptor-family kinase inhibitors was optimized starting from a globally selective lead molecule 4 through structural modifications aimed at improving the physiochemical and pharmacokinetic properties, as exemplified by 18b. Further clearance reduction via per-methylation of the α-carbons of a solubilizing piperidine nitrogen resulted in advanced leads 22a and 22b. Results from a mouse tumor xenograft, a collagen-induced arthritis model, and a 7 day rat in vivo tolerability study culminated in the selection of compound 22b (AC710) as a preclinical development candidate.

Discovery of highly potent and selective pan-Aurora kinase inhibitors with enhanced in vivo antitumor therapeutic index.

Serine/threonine protein kinases Aurora A, B, and C play essential roles in cell mitosis and cytokinesis. Currently a number of Aurora kinase inhibitors with different isoform selectivities are being evaluated in the clinic. Herein we report the discovery and characterization of 21c (AC014) and 21i (AC081), two structurally novel, potent, kinome-selective pan-Aurora inhibitors.

EDTA-dependent platelet phagocytosis. A cytochemical, ultrastructural, and functional characterization.

Platelet satellitosis of polymorphonuclear cells is a phenomenon induced or enhanced by the anticoagulant EDTA. In contrast with previously reported studies, the subject in the present case did not demonstrate platelet satellitism but was profoundly pseudothrombocytopenic owing to platelet phagocytosis. Virtually all polymorphonuclear leukocytes and monocytes contained numerous ingested platelets in contrast with previous cases in which phagocytosis was observed only rarely and involved ingestion of single cells.

Preclinical safety evaluation of avasimibe in beagle dogs: an ACAT inhibitor with minimal adrenal effects.

Avasimibe, a novel inhibitor of acyl coenzyme A:cholesterol acyltransferase (ACAT), is currently being developed as an antiatherosclerotic agent. The preclinical safety and toxicokinetics of the compound were assessed in beagle dogs in an escalating-dose study and in repeated-dose studies of 2-, 13-, and 52-week duration. Oral (capsule) doses up to 1000 mg/kg b.

Troglitazone-induced heart and adipose tissue cell proliferation in mice.

Troglitazone, a thiazolidinedione, is a novel agent for the oral treatment of non-insulin-dependent (Type II) diabetes mellitus; it works by increasing cell sensitivity to available insulin. Previous studies have shown that rodents treated with high doses of troglitazone develop increased heart weight and increased interscapular brown fat. This study investigated cellular proliferation in heart and brown fat of troglitazone-treated mice as well as possible interactions with an angiotensin-converting enzyme inhibitor (quinipril).

An epizootic of lymphoplasmacytic gastritis attributed to Helicobacter pylori infection in cynomolgus monkeys (Macaca fascicularis).

An epizootic of subclinical lymphoplasmacytic gastritis occurred in cynomolgus monkeys maintained at our research facility. Gastric pathology data and histologic sections of 63 adolescent monkeys (2.5-3.

Nitro-imidazole radiosensitizer-induced toxicity in cynomolgus monkeys.

Intravenously administered nitro-imidazole radiosensitizer and alkylating anticancer compound CI-1010, designated as (R)-alpha-[[(2-bromoethyl)amino]methyl]-2-nitro-1H-imidazole-1-ethanol monohydrobromide, causes multiorgan toxicity in rodents, including retinal degeneration. This study determined the potential of CI-1010 to induce similar effects in nonhuman primates. One male and 1 female cynomolgus monkey were given single daily doses of CI-1010 intravenously for 5 consecutive days each week for 3 wk.

Effects of troglitazone and pioglitazone on cytokine-mediated endothelial cell proliferation in vitro.

We examined whether troglitazone and pioglitazone, antidiabetic thiazolidinediones, would directly induce endothelial cell proliferation or influence cytokine-driven proliferation in vitro. Monolayers of Balb/c mouse aortic endothelial cells were treated with troglitazone or pioglitazone in the absence of fetal bovine serum. Endothelial cells also were exposed to varying concentrations of basic fibroblast growth factor (bFGF) or insulin with or without either thiazolidinedione.

Retinal degeneration in rats induced by CI-1010, a 2-nitroimidazole radiosensitizer.

The anti-cancer compound CI-1010, designated as (R)-alpha-([(2-bromoethyl)amino]methyl)-2-nitro-1H-imidazole-1-ethanol monohydrobromide, has a proposed dual mechanism of action due to alkylating and radiosensitizing activities. To assess potential toxicity, adult Wistar rats were treated with a single intravenous injection (0, 50, 100, 150, 225, or 350 mg/kg) and necropsied at 4 or 29 days following treatment. In a repeated dose experiment, rats were injected daily (0, 10, 40, or 80 mg/kg; 5 doses/wk) for 3 wk and necropsied at the end of week 3 or 7.

Intercellular adhesion molecule-1 expression in dextran sodium sulfate-induced colitis in rats.

Orally administered dextran sodium sulfate (DSS) produces an acute colitis in rodents. The pathogenesis is unknown but may relate to DSS-mediated toxicity of colonic crypt epithelium and/or DSS-induced inflammation. The purpose of this study was to determine when colonic mucosal inflammation, as indicated by histopathology and intercellular adhesion molecule-1 (ICAM-1) expression, occurs relative to crypt epithelial damage.

Gastric gland degeneration induced in monkeys by the CCK-B/gastrin receptor antagonist CI-988.

Gastric effects of subchronic treatment with the cholecystokinin-B (CCK-B)/gastrin receptor antagonist CI-988 were investigated in cynomolgus monkeys. In preliminary range-finding studies, CI-988 was given orally to 1 monkey per sex for 14 days at doses of 50, 100, 200, and 500 mg/kg/day. Subchronic studies of CI-988 were subsequently conducted using 5 monkeys per sex at doses of 0, 5, 25, and 75 mg/kg for 4 or 13 wk.

Cellular hyperplasia in rats following continuous intravenous infusion of recombinant human epidermal growth factor.

In this study, we determined in vivo morphologic effects of continuous intravenous infusion of recombinant human epidermal growth factor (EGF) in adult Wistar rats. The EGF used consisted of the amino acid residues 1-48 of the human 53-amino-acid EGF molecule, purified from transfected Escherichia coli. Doses of 25, 100, or 250 micrograms/kg body weight were administered using Harvard digital syringe infusion pumps for 4 weeks.

Soluble CD14 and lipopolysaccharide-binding protein from bovine serum enable bacterial lipopolysaccharide-mediated cytotoxicity and activation of bovine vascular endothelial cells in vitro.

Bacterial endotoxin (lipopolysaccharide, LPS) has potent proinflammatory properties toward many cell types, including vascular endothelial cells. Bovine endothelial cells are often used for investigations involving the vascular endothelium in vitro, and other bovine products such as fetal bovine serum are also widely utilized in research laboratories. Evidence is presented that soluble CD14 (sCD14) is present in bovine serum and that LPS-mediated activation and cytotoxicity to bovine endothelial cells in vitro are dependent on sCD14.

Treatment of mycotic rhinitis with itraconazole in three horses.

Itraconazole, a third-generation azole, was evaluated for treatment of resistant nasal mycotic infections in horses. Two horses with Aspergillus spp nasal granulomas and 1 horse with Conidiobolus coronatus nasal infection were treated with itraconazole (3 mg/kg PO bid). One of the horses with nasal aspergillosis was also treated by surgical resection of the nasal septum.

Signal transduction pathways of bacterial lipopolysaccharide-stimulated bovine vascular endothelial cells.

Increased procoagulant activity of vascular endothelial cells may be an important component in the pathogenesis of intravascular coagulation associated with gram-negative bacterial diseases. Two bovine endothelial cell (BEC) lines isolated from pulmonary arteries (ENS-2 and ENT-18) were used in this study to investigate procoagulant signal transduction pathways of endotoxin (lipopolysaccharide, LPS)--stimulated BECs. The endothelial cell line ENS-2 was sensitive to LPS as demonstrated by tissue factor (TF) expression, but in contrast, the ENT-18 endothelial cell line was unusually resistant to the effects of LPS.

Tissue factor expression in bovine endothelial cells induced by Pasteurella haemolytica lipopolysaccharide and interleukin-1.

Pasteurella haemolytica in cattle produces fibrino-hemorrhagic pleuropneumonia characterized by extensive pulmonary microvascular thrombosis and parenchymal necrosis. The purpose of this in vitro study was to determine if P. haemolytica lipopolysaccharide (LPS) promotes vascular thrombosis by inducing a procoagulant state in vascular endothelial cells.

Tumor cell-enhanced sensitivity of vascular endothelial cells to photodynamic therapy.

Effective antitumor photodynamic therapy (PDT) may be related to damage of vasculature within the tumor. The purpose of this study was to determine if tumor cells secrete factors that stimulate proliferation of human umbilical vein endothelial cells (HUVEC) and result in enhanced sensitivity of HUVEC to aluminum-sulfonated phthalocyanine (AlSPc)-PDT. Three human tumor cell lines--pharyngeal squamous carcinoma, colonic carcinoma, and mammary carcinoma--were used in this study.

Failure of ozone and nitrogen dioxide to enhance lung tumor development in hamsters.

We tested the hypothesis that the two common oxidant air pollutants, ozone and nitrogen dioxide, modulate the development of respiratory tract tumors in Syrian golden hamsters. The animals received subcutaneous injections of the carcinogen diethylnitrosamine (20 mg/kg) twice a week while being exposed continuously to an atmosphere of 0.8 parts per million (ppm)* of ozone or 15 ppm of nitrogen dioxide.

Cytokine modulation of endothelial cell sensitivity to photodynamic therapy.

The purpose of this study was to determine if recombinant angiogenic cytokines modulate the sensitivity of endothelial cells to the toxic effects of chloroaluminum sulphonated phthalocyanine (AlSPc) photodynamic therapy (PDT). Bovine pulmonary artery endothelial cells in 24-well tissue culture plates were pretreated for 24 hr with AlSPc and either acidic fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), tumor necrosis factor-alpha (TNF), interleukin-1-alpha (IL-1), or transforming growth factor-beta (TGF) followed by argon-pumped dye laser. Endothelial cell damage was monitored with 51chromium release.