Identification of ADAM10 as a major source of HER2 ectodomain sheddase activity in HER2 overexpressing breast cancer cells.

Overexpression and activating mutations of ErbB family members have been implicated in the development and progression of a variety of tumor types. Cleavage of the HER2 receptor by an as yet unidentified ectodomain sheddase has been shown to liberate the HER2 extracellular domain (ECD) leaving a fragment with constitutive kinase activity that can provide ligand-independent growth and survival signals to the cell. This process is clinically relevant since HER2 ECD serum levels in metastatic breast cancer patients are associated with a poorer prognosis. Thus, inhibition of the HER2 sheddase may provide a novel therapeutic approach for breast cancer. We describe the use of transcriptional profiling, pharmacological and in vitro approaches to identify the major source of HER2 sheddase activity. Real-time PCR was used to identify those ADAM family members which were expressed in HER2 shedding cell lines. siRNAs that selectively inhibited ADAM10 expression reduced HER2 shedding. In addition, we profiled over 1000 small molecules for in vitro inhibition of a panel of ADAM and MMP proteins; a positive correlation was observed only between ADAM10 inhibition and reduction of HER2 ECD shedding in a cell based assay. Finally, in vitro studies demonstrate that in combination with low doses of Herceptin, selective ADAM10 inhibitors decrease proliferation in HER2 overexpressing cell lines while inhibitors, that do not inhibit ADAM10, have no impact. These results are consistent with ADAM10 being a major determinant of HER2 shedding, the inhibition of which, may provide a novel therapeutic approach for treating a variety of cancers with active HER2 signaling.

Induction of endogenous genes by peroxisome proliferator activated receptor alpha ligands in a human kidney cell line and in vivo.

The peroxisome proliferator activated receptor alpha (PPARalpha) plays a key role in regulating fatty acid metabolism by regulating expression of genes involved in fatty acid oxidation. To identify endogenous transcripts that could be used as surrogate markers for on-target activity of PPARalpha agonists, we employed a global profiling approach using DNA microarrays. The HK-2 cell line derived from proximal tubules of the human kidney, showed induction of several genes, including pyruvate dehydrogenase kinase 4 (PDK-4) and adipocyte differentiation related protein (ADRP) by PPARalpha ligands. HK-2 cells express detectable levels of PPARalpha and its dimerization partner the retinoid X receptor (RXRalpha) proteins. Induction of PDK-4 in these cells correlates with induction of PDK-4 in the liver of fat-fed hamsters. The magnitude of fibrate induction of PDK-4 in the liver also mirrors the decrease in serum triglyceride levels. Thus, induction of PDK-4 by PPARalpha agonists in the HK-2 cell model closely correlates with its induction in vivo and may represent an early marker for PPARalpha agonist action.

Safety and immunogenicity of a plant-produced recombinant hemagglutinin-based influenza vaccine (HAI-05) derived from A/Indonesia/05/2005 (H5N1) influenza virus: a phase 1 randomized, double-blind, placebo-controlled, dose-escalation study in healthy adults.

Recently, we have reported [1,2] on a subunit influenza vaccine candidate based on the recombinant hemagglutinin protein from the A/Indonesia/05/2005 (H5N1) strain of influenza virus, produced it using 'launch vector'-based transient expression technology in Nicotiana benthamiana, and demonstrated its immunogenicity in pre-clinical studies. Here, we present the results of a first-in-human, Phase 1 randomized, double-blind, placebo-controlled study designed to investigate safety, reactogenicity and immunogenicity of three escalating dose levels of this vaccine, HAI-05, (15, 45 and 90 µg) adjuvanted with Alhydrogel® (0.75 mg aluminum per dose) and the 90 µg dose level without Alhydrogel®. Vaccine was administered intramuscularly in two injections three weeks apart to healthy adults of 18-49 years of age. At all dose levels the vaccine was generally safe and well tolerated, with no reported serious adverse events or dose-limiting toxicities. Mild local and systemic reactions were observed in all vaccine dose groups and the placebo group and their occurrence was not dose related. The incidence rates were higher in the groups receiving vaccine with Alhydrogel®. The immune response elicited by the HAI-05 vaccine was variable with respect to both hemagglutination-inhibition and virus microneutralization antibody titers, with the highest responses observed in the 90 µg unadjuvanted group.

Discovery and pharmacological characterization of a novel rodent-active CCR2 antagonist, INCB3344.

This report describes the characterization of INCB3344, a novel, potent and selective small molecule antagonist of the mouse CCR2 receptor. The lack of rodent cross-reactivity inherent in the small molecule CCR2 antagonists discovered to date has precluded pharmacological studies of antagonists of this receptor and its therapeutic relevance. In vitro, INCB3344 inhibits the binding of CCL2 to mouse monocytes with nanomolar potency (IC(50) = 10 nM) and displays dose-dependent inhibition of CCL2-mediated functional responses such as ERK phosphorylation and chemotaxis with similar potency. Against a panel of G protein-coupled receptors that includes other CC chemokine receptors, INCB3344 is at least 100-fold selective for CCR2. INCB3344 possesses good oral bioavailability and systemic exposure in rodents that allows in vivo pharmacological studies. INCB3344 treatment results in a dose-dependent inhibition of macrophage influx in a mouse model of delayed-type hypersensitivity. The histopathological analysis of tissues from the delayed-type hypersensitivity model demonstrates that inhibition of CCR2 leads to a substantial reduction in tissue inflammation, suggesting that macrophages play an orchestrating role in immune-based inflammatory reactions. These results led to the investigation of INCB3344 in inflammatory disease models. We demonstrate that therapeutic dosing of INCB3344 significantly reduces disease in mice subjected to experimental autoimmune encephalomyelitis, a model of multiple sclerosis, as well as a rat model of inflammatory arthritis. In summary, we present the first report on the pharmacological characterization of a selective, potent and rodent-active small molecule CCR2 antagonist. These data support targeting this receptor for the treatment of chronic inflammatory diseases.

Antisense oligonucleotides selectively regulate aspartyl beta-hydroxylase and its truncated protein isoform in vitro but distribute poorly into A549 tumors in vivo.

Alternative splicing of the human beta-aspartyl (asparaginyl) hydroxylase (BAH) gene results in the expression of humbug, a truncated form of BAH that lacks the catalytic domain of the enzyme. Overexpression of BAH and humbug has been associated with a variety of human cancers, and although humbug lacks enzymatic activity, it is expressed at levels comparable with that of BAH in various cancer cell lines. Phosphorothioate antisense oligonucleotides (ONs) were designed to dissect out the function of these hydroxylase protein isoforms. In A549 cells, these ONs differentially down-regulated BAH and humbug at the mRNA and protein level. Phosphorothioate ON uptake and antisense studies were conducted in parallel in nude mice bearing A549 tumor xenografts. Microscopic examination of the tumor after administration of a fluorescein-labeled ON showed strong labeling of the outer layers of the tumor connective tissue but cells within the interior of the tumor were sparsely labeled. A modest but significant effect on tumor growth was observed in animals treated with an antisense ON directed against both BAH and humbug transcripts. However, Northern analysis of tumor RNA did not indicate a down-regulation of the targeted mRNA species. These results demonstrate the successful development of antisense ONs that selectively differentiate between the closely related beta-hydroxylase protein isoforms. However, determination of the biological function of these proteins in vivo was limited by the poor uptake properties of phosphorothioate ONs in A549 tumors.