Polymer Nanovesicle-Mediated Delivery of MLN8237 Preferentially Inhibits Aurora Kinase A To Target RalA and Anchorage-Independent Growth in Breast Cancer Cells

Mol Pharm. 2018 Aug 6;15(8):3046-3059. doi: 10.1021/acs.molpharmaceut.8b00163. Epub 2018 Jun 22.

Abstract

The small GTPase RalA is a known mediator of anchorage-independent growth in cancers and is differentially regulated by adhesion and aurora kinase A (AURKA). Hence, inhibiting AURKA offers a means of specifically targeting RalA (over RalB) in cancer cells. MLN8237 (alisertib) is a known inhibitor of aurora kinases; its specificity for AURKA, however, is compromised by its poor solubility and transport across the cell membrane. A polymer nanovesicle platform is used for the first time to deliver and differentially inhibit AURKA in cancer cells. For this purpose, polysaccharide nanovesicles made from amphiphilic dextran were used as nanocarriers to successfully administer MLN8237 (VMLN) in cancer cells in 2D and 3D microenvironments. These nanovesicles (<200 nm) carry the drug in their intermembrane space with up to 85% of it released by the action of esterase enzyme(s). Lysotracker experiments reveal the polymer nanovesicles localize in the lysosomal compartment of the cell, where they are enzymatically targeted and MLN released in a controlled manner. Rhodamine B fluorophore trapped in the nanovesicles hydrophilic core (VMLN+RhB) allows us to visualize its uptake and localization in cells in a 2D and 3D microenvironment. In breast cancer, MCF-7 cells VMLN inhibits AURKA significantly better than the free drug at low concentrations (0.02-0.04 μM). This ensures that the drug in VMLN at these concentrations can specifically inhibit up to 94% of endogenous AURKA without affecting AURKB. This targeting of AURKA causes the downstream differential inhibition of active RalA (but not RalB). Free MLN8237 at similar concentrations and conditions failed to affect RalA activation. VMLN-mediated inhibition of RalA, in turn, disrupts the anchorage-independent growth of MCF-7 cells supporting a role for the AURKA-RalA crosstalk in mediating the same. These studies not only identify the polysaccharide nanovesicle to be an improved way to efficiently deliver low concentrations of MLN8237 to inhibit AURKA but, in doing so, also help reveal a role for AURKA and its crosstalk with RalA in anchorage-independent growth of MCF-7 cells.

Keywords: AURKA; BQU57; MLN8237; RalA; anchorage-independent growth; aurora kinase; polymer nanovesicle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aurora Kinase A / antagonists & inhibitors*
  • Azepines / administration & dosage*
  • Azepines / pharmacokinetics
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology
  • Cell Adhesion / drug effects
  • Cell Membrane Permeability / drug effects
  • Dextrans / chemistry
  • Dextrans / pharmacology
  • Drug Carriers / chemistry*
  • Drug Carriers / pharmacology
  • Drug Compounding / methods
  • Drug Liberation
  • Drug Screening Assays, Antitumor
  • Drug Stability
  • Female
  • Humans
  • MCF-7 Cells
  • Nanoparticles / chemistry
  • Protein Kinase Inhibitors / administration & dosage*
  • Protein Kinase Inhibitors / pharmacokinetics
  • Pyrimidines / administration & dosage*
  • Pyrimidines / pharmacokinetics
  • Solubility
  • Surface-Active Agents / chemistry
  • Surface-Active Agents / pharmacology
  • ral GTP-Binding Proteins / metabolism

Substances

  • Azepines
  • Dextrans
  • Drug Carriers
  • MLN 8237
  • Protein Kinase Inhibitors
  • Pyrimidines
  • Surface-Active Agents
  • AURKA protein, human
  • Aurora Kinase A
  • RALA protein, human
  • ral GTP-Binding Proteins