title: Tumor-Targeted Synergistic Blockade of MAPK and PI3K from a Layer-by-Layer Nanoparticle.
abstract: OBJECTIVE
  Cross-talk and feedback between the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR cell signaling pathways is critical for tumor initiation, maintenance, and adaptive resistance to targeted therapy in a variety of solid tumors. Combined blockade of these pathways-horizontal blockade-is a promising therapeutic strategy; however, compounded dose-limiting toxicity of free small molecule inhibitor combinations is a significant barrier to its clinical application.
  
  
  METHODS
  AZD6244 (selumetinib), an allosteric inhibitor of Mek1/2, and PX-866, a covalent inhibitor of PI3K, were co-encapsulated in a tumor-targeting nanoscale drug formulation-layer-by-layer (LbL) nanoparticles. Structure, size, and surface charge of the nanoscale formulations were characterized, in addition to in vitro cell entry, synergistic cell killing, and combined signal blockade. In vivo tumor targeting and therapy was investigated in breast tumor xenograft-bearing NCR nude mice by live animal fluorescence/bioluminescence imaging, Western blotting, serum cytokine analysis, and immunohistochemistry.
  
  
  RESULTS
  Combined MAPK and PI3K axis blockade from the nanoscale formulations (160 ± 20 nm, -40 ± 1 mV) was synergistically toxic toward triple-negative breast (MDA-MB-231) and RAS-mutant lung tumor cells (KP7B) in vitro, effects that were further enhanced upon encapsulation. In vivo, systemically administered LbL nanoparticles preferentially targeted subcutaneous MDA-MB-231 tumor xenografts, simultaneously blocked tumor-specific phosphorylation of the terminal kinases Erk and Akt, and elicited significant disease stabilization in the absence of dose-limiting hepatotoxic effects observed from the free drug combination. Mice receiving untargeted, but dual drug-loaded nanoparticles exhibited progressive disease.
  
  
  CONCLUSIONS
  Tumor-targeting nanoscale drug formulations could provide a more safe and effective means to synergistically block MAPK and PI3K in the clinic.
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Erik C
authors.initials: EC
authors.lastname: Dreaden
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Yi Wen
authors.initials: YW
authors.lastname: Kong
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Morton
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Santiago
authors.initials: S
authors.lastname: Correa
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Ki Young
authors.initials: KY
authors.lastname: Choi
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Shopsowitz
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
authors.forename: Kasper
authors.initials: K
authors.lastname: Renggli
authors.affiliation: Penn Ovarian Cancer Research Center, Basser Research Center for BRCA, University of Pennsylvania, Philadelphia, Pennsylvania. Perelman Center for Advanced Medicine, Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania. Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Ronny
authors.initials: R
authors.lastname: Drapkin
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts. Division of Acute Care Surgery, Trauma, and Critical Care, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts. hammond@mit.edu myaffe@mit.edu.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Yaffe
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts. Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts. Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts. hammond@mit.edu myaffe@mit.edu.
authors.forename: Paula T
authors.initials: PT
authors.lastname: Hammond
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004357:Drug Synergism; D005260:Female; D006801:Humans; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage* / Q000737:chemistry; D015398:Signal Transduction / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors