title: Molecular pharmacology and antitumor activity of PHT-427, a novel Akt/phosphatidylinositide-dependent protein kinase 1 pleckstrin homology domain inhibitor.
abstract: 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.
authors.affiliation: Departments of Nutritional Sciences and Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA.
authors.forename: Emmanuelle J
authors.initials: EJ
authors.lastname: Meuillet
authors.forename: Song
authors.initials: S
authors.lastname: Zuohe
authors.forename: Robert
authors.initials: R
authors.lastname: Lemos
authors.forename: Nathan
authors.initials: N
authors.lastname: Ihle
authors.forename: John
authors.initials: J
authors.lastname: Kingston
authors.forename: Ryan
authors.initials: R
authors.lastname: Watkins
authors.forename: Sylvestor A
authors.initials: SA
authors.lastname: Moses
authors.forename: Shuxing
authors.initials: S
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Du-Cuny
authors.forename: Roy
authors.initials: R
authors.lastname: Herbst
authors.forename: Jörg J
authors.initials: JJ
authors.lastname: Jacoby
authors.forename: Li Li
authors.initials: LL
authors.lastname: Zhou
authors.forename: Ali M
authors.initials: AM
authors.lastname: Ahad
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Mash
authors.forename: D Lynn
authors.initials: DL
authors.lastname: Kirkpatrick
authors.forename: Garth
authors.initials: G
authors.lastname: Powis
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D008954:Models, Biological; D051058:Oncogene Protein v-akt / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D054730:Protein Interaction Domains and Motifs / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D013449:Sulfonamides / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D013830:Thiadiazoles / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D000096926:Benzenesulfonamides
chemical_list: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000970:Antineoplastic Agents; D051058:Oncogene Protein v-akt; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D013449:Sulfonamides; D013830:Thiadiazoles; C550093:4-dodecyl-N-(1,3,4-thiadiazol-2-yl)benzenesulfonamide; D000096926:Benzenesulfonamides; C578562:PDPK1 protein, human; C578564:Pdpk1 protein, mouse