Subject(s)
Spinal Cord Neoplasms/diagnostic imaging , Spinal Cord/diagnostic imaging , Bone Cysts, Aneurysmal/diagnostic imaging , Chordoma/diagnostic imaging , Humans , Magnetic Resonance Imaging , Nerve Sheath Neoplasms/diagnostic imaging , Neurilemmoma/diagnostic imaging , Neurofibroma/diagnostic imaging , Plasmacytoma/diagnostic imaging , Spinal Cord Neoplasms/secondary , Synovial Cyst/diagnostic imaging , Tomography, X-Ray ComputedABSTRACT
Disruption of the phosphatidylinositol 3-kinase/AKT signaling pathway can lead to apoptosis in cancer cells. Previously we identified a lead sulfonamide that selectively bound to the pleckstrin homology (PH) domain of AKT and induced apoptosis when present at low micromolar concentrations. To examine the effects of structural modification, a set of sulfonamides related to the lead compound was designed, synthesized, and tested for binding to the expressed PH domain of AKT using a surface plasmon resonance-based competitive binding assay. Cellular activity was determined by means of an assay for pAKT production and a cell killing assay using BxPC-3 cells. The most active compounds in the set are lipophilic and possess an aliphatic chain of the proper length. Results were interpreted with the aid of computational modeling. This paper represents the first structure-activity relationship (SAR) study of a large family of AKT PH domain inhibitors. Information obtained will be used in the design of the next generation of inhibitors of AKT PH domain function.
Subject(s)
Protein Kinase Inhibitors/chemistry , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Sulfonamides/chemistry , Binding Sites , Cell Line, Tumor , Computer Simulation , Humans , Protein Binding , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Protein Structure, Tertiary , Proto-Oncogene Proteins c-akt/metabolism , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/pharmacologyABSTRACT
Phosphatidylinositol 3-kinase/phosphatidylinositide-dependent protein kinase 1 (PDPK1)/Akt signaling plays a critical role in activating proliferation and survival pathways within cancer cells. We report the molecular pharmacology and antitumor activity of PHT-427, a compound designed to bind to the pleckstrin homology (PH) binding domain of signaling molecules important in cancer. Although originally designed to bind the PH domain of Akt, we now report that PHT-427 also binds to the PH domain of PDPK1. A series of PHT-427 analogues with variable C-4 to C-16 alkyl chain length were synthesized and tested. PHT-427 itself (C-12 chain) bound with the highest affinity to the PH domains of both PDPK1 and Akt. PHT-427 inhibited Akt and PDPK1 signaling and their downstream targets in sensitive but not resistant cells and tumor xenografts. When given orally, PHT-427 inhibited the growth of human tumor xenografts in immunodeficient mice, with up to 80% inhibition in the most sensitive tumors, and showed greater activity than analogues with C4, C6, or C8 alkyl chains. Inhibition of PDPK1 was more closely correlated to antitumor activity than Akt inhibition. Tumors with PIK3CA mutation were the most sensitive, and K-Ras mutant tumors were the least sensitive. Combination studies showed that PHT-427 has greater than additive antitumor activity with paclitaxel in breast cancer and with erlotinib in non-small cell lung cancer. When given >5 days, PHT-427 caused no weight loss or change in blood chemistry. Thus, we report a novel PH domain binding inhibitor of PDPK1/Akt signaling with significant in vivo antitumor activity and minimal toxicity.
Subject(s)
Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/therapeutic use , Oncogene Protein v-akt/antagonists & inhibitors , Protein Serine-Threonine Kinases/antagonists & inhibitors , Sulfonamides/pharmacokinetics , Sulfonamides/therapeutic use , Thiadiazoles/pharmacokinetics , Thiadiazoles/therapeutic use , 3-Phosphoinositide-Dependent Protein Kinases , Animals , Antineoplastic Agents/adverse effects , Female , Humans , Mice , Mice, Inbred C57BL , Mice, Nude , Models, Biological , Oncogene Protein v-akt/chemistry , Oncogene Protein v-akt/metabolism , Protein Binding/drug effects , Protein Interaction Domains and Motifs/drug effects , Protein Kinase Inhibitors/adverse effects , Protein Kinase Inhibitors/pharmacokinetics , Protein Kinase Inhibitors/therapeutic use , Protein Serine-Threonine Kinases/chemistry , Protein Serine-Threonine Kinases/metabolism , Tumor Cells, Cultured , Xenograft Model Antitumor AssaysABSTRACT
The phosphatidylinositol 3-kinase/AKT signaling pathway plays a critical role in activating survival and antiapoptotic pathways within cancer cells. Several studies have shown that this pathway is constitutively activated in many different cancer types. The goal of this study was to discover novel compounds that bind to the pleckstrin homology (PH) domain of AKT, thereby inhibiting AKT activation. Using proprietary docking software, 22 potential PH domain inhibitors were identified. Surface plasmon resonance spectroscopy was used to measure the binding of the compounds to the expressed PH domain of AKT followed by an in vitro activity screen in Panc-1 and MiaPaCa-2 pancreatic cancer cell lines. We identified a novel chemical scaffold in several of the compounds that binds selectively to the PH domain of AKT, inducing a decrease in AKT activation and causing apoptosis at low micromolar concentrations. Structural modifications of the scaffold led to compounds with enhanced inhibitory activity in cells. One compound, 4-dodecyl-N-(1,3,4-thiadiazol-2-yl)benzenesulfonamide, inhibited AKT and its downstream targets in cells as well as in pancreatic cancer cell xenografts in immunocompromised mice; it also exhibited good antitumor activity. In summary, a pharmacophore for PH domain inhibitors targeting AKT function was developed. Computer-aided modeling, synthesis, and testing produced novel AKT PH domain inhibitors that exhibit promising preclinical properties.
