ABSTRACT
Pancreas ductal adenocarcinoma (PDAC) is a highly lethal cancer that typically presents as advanced, unresectable disease. This invasive tendency, coupled with intrinsic resistance to standard therapies and genome instability, are major contributors to poor long-term survival. The genetic elements governing the invasive propensity of PDAC have not been well elucidated. Here, in the course of validating resident genes in highly recurrent and focal amplifications in PDAC, we have identified Rio Kinase 3 (RIOK3) as an amplified gene that alters cytoskeletal architecture as well as promotes pancreatic ductal cell migration and invasion. We determined that RIOK3 promotes its invasive activities through activation of the small G protein, Rac. This genomic and functional link to Rac signaling prompted a genome wide survey of other components of the Rho family network, revealing p21 Activated Kinase 4 (PAK4) as another amplified gene in PDAC tumors and cell lines. Like RIOK3, PAK4 promotes pancreas ductal cell motility and invasion. Together, the genomic and functional profiles establish the Rho family GTP-binding proteins as integral to the hallmark invasive nature of this lethal disease.
Subject(s)
Carcinoma, Pancreatic Ductal/genetics , Pancreatic Ducts/physiology , Pancreatic Neoplasms/genetics , Protein Serine-Threonine Kinases/genetics , p21-Activated Kinases/genetics , rho GTP-Binding Proteins/genetics , Animals , Carcinoma, Pancreatic Ductal/pathology , Cell Line, Transformed , Cell Movement/physiology , Gene Expression Regulation, Neoplastic , Genomics , Humans , Mice , Mice, Nude , Neoplasm Invasiveness , Pancreatic Ducts/cytology , Pancreatic Neoplasms/pathology , Phenotype , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction/physiology , p21-Activated Kinases/metabolism , rho GTP-Binding Proteins/metabolismABSTRACT
Targeted therapies that inhibit receptor tyrosine kinases (RTKs) and the downstream phosphatidylinositol 3-kinase (PI3K) signaling pathway have shown promising anticancer activity, but their efficacy in the brain tumor glioblastoma multiforme (GBM) and other solid tumors has been modest. We hypothesized that multiple RTKs are coactivated in these tumors and that redundant inputs drive and maintain downstream signaling, thereby limiting the efficacy of therapies targeting single RTKs. Tumor cell lines, xenotransplants, and primary tumors indeed show multiple concomitantly activated RTKs. Combinations of RTK inhibitors and/or RNA interference, but not single agents, decreased signaling, cell survival, and anchorage-independent growth even in glioma cells deficient in PTEN, a frequently inactivated inhibitor of PI3K. Thus, effective GBM therapy may require combined regimens targeting multiple RTKs.
Subject(s)
Antineoplastic Agents/pharmacology , Brain Neoplasms/enzymology , Glioblastoma/enzymology , Protein Kinase Inhibitors/pharmacology , Receptor Protein-Tyrosine Kinases/metabolism , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Brain Neoplasms/drug therapy , Cell Line, Tumor , Cell Survival , Enzyme Activation , ErbB Receptors/antagonists & inhibitors , ErbB Receptors/metabolism , Erlotinib Hydrochloride , Glioblastoma/drug therapy , Humans , Indoles/pharmacology , PTEN Phosphohydrolase/genetics , PTEN Phosphohydrolase/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Phosphorylation , Piperazines/pharmacology , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins c-met , Quinazolines/pharmacology , Receptor Protein-Tyrosine Kinases/antagonists & inhibitors , Receptors, Growth Factor/metabolism , Signal Transduction , Sulfonamides/pharmacologyABSTRACT
Fragment-based virtual library design and virtual screening have been conducted against malic enzyme (ME) homology model. Several scaffolds have been identified as promising motifs to target ME's NADP binding site. One small focused library has been synthesized and tested against ME. Several compounds from this library have shown sub-micromolar inhibitory activity against malic enzyme.
Subject(s)
Combinatorial Chemistry Techniques/methods , Enzyme Inhibitors/chemical synthesis , Malate Dehydrogenase/metabolism , Piperazines/chemical synthesis , Pyrrolidinones/chemical synthesis , Binding Sites , Cytosol/enzymology , Drug Design , Enzyme Inhibitors/pharmacology , Humans , NADP/metabolism , Piperazine , Piperazines/chemistry , Piperazines/pharmacology , Protein Conformation , Pyrrolidines/chemical synthesis , Pyrrolidines/pharmacology , Pyrrolidinones/pharmacology , Structure-Activity RelationshipABSTRACT
Interferon-beta (IFN-beta) is biologically unstable under physiologic conditions in vitro and is cleared rapidly from the bloodstream on administration in vivo. In the present study, we demonstrate that a soluble recombinant form of the type I IFN receptor subunit, sIFNAR-2, can neutralize the bioactivity of type I IFNs at high concentrations and, at lower concentrations, causes an enhancement of IFN-beta-mediated antiviral activity. The in vitro enhancement is due to the specific interaction of IFN-beta with sIFNAR-2, followed by dissociation of IFN-beta from the complex over time in culture. In vivo, the serum half-life of IFN-beta is extended from minutes to hours when administered intravenously in mice as a sIFNAR-2-associated complex. Moreover, the antitumor effect of IFN-beta is increased by between 9-fold and 27-fold when injected as an sIFNAR-2-associated complex, as demonstrated by an increase in the mean survival time of immunodeficient mice challenged with human Burkitt lymphoma cell (Daudi) xenografts (sIFNAR-2-complexed vs. free IFN-beta treatment). These results show that on association with sIFNAR-2, IFN-beta is more stable in vitro and exhibits increased efficacy when administered in vivo. Administration as a complex with sIFNAR-2 may, therefore, provide a method of enhancing the delivery and effectiveness of type I IFNs.