Soluble CLEC2 Extracellular Domain Improves Glucose and Lipid Homeostasis by Regulating Liver Kupffer Cell Polarization.

The polarization of tissue resident macrophages toward the alternatively activated, anti-inflammatory M2 phenotype is believed to positively impact obesity and insulin resistance. Here we show that the soluble form of the extracellular domain (ECD) of C-type lectin-like receptor 2, CLEC2, regulates Kupffer cell polarization in the liver and improves glucose and lipid parameters in diabetic animal models. Over-expression of Fc-CLEC2(ECD) in mice via in vivo gene delivery, or injection of recombinant Fc-CLEC2(ECD) protein, results in a reduction of blood glucose and liver triglyceride levels and improves glucose tolerance. Furthermore, Fc-CLEC2(ECD) treatment improves cytokine profiles and increases both the M2 macrophage population and the genes involved in the oxidation of lipid metabolism in the liver. These data reveal a previously unidentified role for CLEC2 as a regulator of macrophage polarity, and establish CLEC2 as a promising therapeutic target for treatment of diabetes and liver disease.

Trefoil Factor 3 (TFF3) Is Regulated by Food Intake, Improves Glucose Tolerance and Induces Mucinous Metaplasia.

Trefoil factor 3 (TFF3), also called intestinal trefoil factor or Itf, is a 59 amino acid peptide found as a homodimer predominantly along the gastrointestinal tract and in serum. TFF3 expression is elevated during gastrointestinal adenoma progression and has been shown to promote mucosal wound healing. Here we show that in contrast to other trefoil factor family members, TFF1 and TFF2, TFF3 is highly expressed in mouse duodenum, jejunum and ileum and that its expression is regulated by food intake. Overexpression of TFF3 using a recombinant adeno-associated virus (AAV) vector, or daily administration of recombinant TFF3 protein in vivo improved glucose tolerance in a diet-induced obesity mouse model. Body weight, fasting insulin, triglyceride, cholesterol and leptin levels were not affected by TFF3 treatment. Induction of mucinous metaplasia was observed in mice with AAV-mediated TFF3 overexpression, however, no such adverse histological effect was seen after the administration of recombinant TFF3 protein. Altogether these results suggest that the therapeutic potential of targeting TFF3 to treat T2D may be limited.

Preclinical evaluation of AMG 925, a FLT3/CDK4 dual kinase inhibitor for treating acute myeloid leukemia.

Acute myeloid leukemia (AML) remains a serious unmet medical need. Despite high remission rates with chemotherapy standard-of-care treatment, the disease eventually relapses in a major proportion of patients. Activating Fms-like tyrosine kinase 3 (FLT3) mutations are found in approximately 30% of patients with AML. Targeting FLT3 receptor tyrosine kinase has shown encouraging results in treating FLT3-mutated AML. Responses, however, are not sustained and acquired resistance has been a clinical challenge. Treatment options to overcome resistance are currently the focus of research. We report here the preclinical evaluation of AMG 925, a potent, selective, and bioavailable FLT3/cyclin-dependent kinase 4 (CDK4) dual kinase inhibitor. AMG 925 inhibited AML xenograft tumor growth by 96% to 99% without significant body weight loss. The antitumor activity of AMG 925 correlated with the inhibition of STAT5 and RB phosphorylation, the pharmacodynamic markers for inhibition of FLT3 and CDK4, respectively. In addition, AMG 925 was also found to inhibit FLT3 mutants (e.g., D835Y) that are resistant to the current FLT3 inhibitors (e.g., AC220 and sorafenib). CDK4 is a cyclin D-dependent kinase that plays an essential central role in regulating cell proliferation in response to external growth signals. A critical role of the CDK4-RB pathway in cancer development has been well established. CDK4-specific inhibitors are being developed for treating RB-positive cancer. AMG 925, which combines inhibition of two kinases essential for proliferation and survival of FLT3-mutated AML cells, may improve and prolong clinical responses.

The RAV12 monoclonal antibody recognizes the N-linked glycotope RAAG12: expression in human normal and tumor tissues.

CONTEXT: RAAG12 is a primate-restricted N-linked carbohydrate antigen present on multiple membrane-associated proteins. RAAG12 is recognized by the RAV12 monoclonal antibody. RAV12 binds to RAAG12-expressing gastrointestinal adenocarcinomas, modifies growth factor-mediated signaling, induces oncotic cell death in vitro, and has antitumor activity toward gastrointestinal tumor xenografts. OBJECTIVE: To determine the expression pattern of RAAG12 in normal and tumor tissue to identify indications for clinical study and potential safety issues. DESIGN: Immunohistochemistry of 36 normal human tissues and a broad range of tumor tissues to profile RAAG12 expression. RESULTS: More than 90% of colon, gastric, and pancreatic adenocarcinomas expressed RAAG12, and expression was uniform in most samples. Expression of RAAG12 at lower frequency and/or uniformity was observed in other cancers, including esophageal, ovarian, liver, breast, and prostate carcinomas and adenocarcinomas. Similar RAAG12 expression was observed between primary and metastatic colon adenocarcinomas. No staining was seen on cardiovascular, endocrine, neuromuscular, hematopoietic, or nervous system tissue from non-tumor-bearing individuals. RAAG12 was expressed on mucosal and glandular/ductal epithelium. The gastrointestinal tract mucosa and pancreatic/biliary ducts displayed the most uniform reactivity. RAAG12 exhibited differential subcellular localization in these normal, compared with tumor, tissues. Normal polarized epithelia primarily displayed apical membrane and cytoplasmic staining, whereas tumors exhibited whole membrane staining that increased with decreasing differentiation. CONCLUSIONS: High expression of RAAG12 on tumors of gastrointestinal origin suggests these cancers are appropriate targets for RAV12 therapy. Differential subcellular location of RAAG12 on normal epithelia may limit accessibility of RAV12 to the subset of normal tissues that exhibit antigen expression.

The glycotope-specific RAV12 monoclonal antibody induces oncosis in vitro and has antitumor activity against gastrointestinal adenocarcinoma tumor xenografts in vivo.

RAV12 is a chimeric antibody that recognizes an N-linked carbohydrate antigen (RAAG12) strongly expressed on multiple solid organ cancers. More than 90% of tumors of colorectal, gastric, and pancreatic origin express RAAG12, and a majority of these tumors exhibit uniform RAAG12 expression. RAV12 exhibits potent cytotoxic activity in vitro against COLO 205 colon tumor cells via an oncotic cell death mechanism. RAV12-treated COLO 205 cells undergo morphologic changes consistent with oncosis, including cytoskeletal rearrangement, rapid plasma membrane swelling, and cell lysis. RAV12 inhibited the growth of RAAG12-expressing gastrointestinal tumor xenografts in athymic mice. In the case of SNU-16 tumor cells, twice weekly treatment of established s.c. tumors with 10 mg/kg RAV12 caused a approximately 70% suppression of tumor growth at the end of the study. This preclinical data has led to the initiation of a phase I/IIA clinical study of RAV12 in patients with metastatic or recurrent adenocarcinoma.