PI-273, a Substrate-Competitive, Specific Small-Molecule Inhibitor of PI4KIIα, Inhibits the Growth of Breast Cancer Cells

Cancer Res. 2017 Nov 15;77(22):6253-6266. doi: 10.1158/0008-5472.CAN-17-0484. Epub 2017 Aug 21.

Abstract

While phosphatidylinositol 4-kinase (PI4KIIα) has been identified as a potential target for antitumor therapy, the clinical applications of PI4KIIα are limited by a lack of specific inhibitors. Here we report the first small-molecule inhibitor (SMI) of human PI4KIIα. Docking-based and ligand-based virtual screening strategies were first employed to identify promising hits, followed by two rounds of kinase activity inhibition validation. 2-(3-(4-Chlorobenzoyl)thioureido)-4-ethyl-5-methylthiophene-3-carboxamide (PI-273) exhibited the greatest inhibitory effect on PI4KIIα kinase activity (IC50 = 0.47 μmol/L) and suppressed cell proliferation. Surface plasmon resonance and thermal shift assays indicated that PI-273 interacted directly with PI4KIIα. Kinetic analysis identified PI-273 as a reversible competitive inhibitor with respect to the substrate phosphatidylinositol (PI), which contrasted with most other PI kinase inhibitors that bind the ATP binding site. PI-273 reduced PI4P content, cell viability, and AKT signaling in wild-type MCF-7 cells, but not in PI4KIIα knockout MCF-7 cells, indicating that PI-273 is highly selective for PI4KIIα. Mutant analysis revealed a role of palmitoylation insertion in the selectivity of PI-273 for PI4KIIα. In addition, PI-273 treatment retarded cell proliferation by blocking cells in G2-M, inducing cell apoptosis and suppressing colony-forming ability. Importantly, PI-273 significantly inhibited MCF-7 cell-induced breast tumor growth without toxicity. PI-273 is the first substrate-competitive, subtype-specific inhibitor of PI4KIIα, the use of which will facilitate evaluations of PI4KIIα as a cancer therapeutic target. Cancer Res; 77(22); 6253-66. ©2017 AACR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cell Proliferation / drug effects*
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacokinetics
  • Enzyme Inhibitors / pharmacology*
  • Female
  • G2 Phase Cell Cycle Checkpoints / drug effects
  • Humans
  • MCF-7 Cells
  • Male
  • Mice, Inbred BALB C
  • Mice, Nude
  • Minor Histocompatibility Antigens / metabolism
  • Molecular Structure
  • Phosphatidylinositols / metabolism
  • Phosphotransferases (Alcohol Group Acceptor) / antagonists & inhibitors*
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism
  • Rats, Sprague-Dawley
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacokinetics
  • Small Molecule Libraries / pharmacology*
  • Substrate Specificity
  • Thiophenes / chemistry
  • Thiophenes / pharmacology*
  • Thiourea / analogs & derivatives*
  • Thiourea / chemistry
  • Thiourea / pharmacology
  • Xenograft Model Antitumor Assays

Substances

  • 2-(3-(4-chlorobenzoyl)thioureido)-4-ethyl-5-methylthiophene-3-carboxamide
  • Enzyme Inhibitors
  • Minor Histocompatibility Antigens
  • Phosphatidylinositols
  • Small Molecule Libraries
  • Thiophenes
  • Phosphotransferases (Alcohol Group Acceptor)
  • phosphatidylinositol phosphate 4-kinase
  • Thiourea