Protein-protein interface-binding peptides inhibit the cancer therapy target human thymidylate synthase

Proc Natl Acad Sci U S A. 2011 Aug 23;108(34):E542-9. doi: 10.1073/pnas.1104829108. Epub 2011 Jul 27.

Abstract

Human thymidylate synthase is a homodimeric enzyme that plays a key role in DNA synthesis and is a target for several clinically important anticancer drugs that bind to its active site. We have designed peptides to specifically target its dimer interface. Here we show through X-ray diffraction, spectroscopic, kinetic, and calorimetric evidence that the peptides do indeed bind at the interface of the dimeric protein and stabilize its di-inactive form. The "LR" peptide binds at a previously unknown binding site and shows a previously undescribed mechanism for the allosteric inhibition of a homodimeric enzyme. It inhibits the intracellular enzyme in ovarian cancer cells and reduces cellular growth at low micromolar concentrations in both cisplatin-sensitive and -resistant cells without causing protein overexpression. This peptide demonstrates the potential of allosteric inhibition of hTS for overcoming platinum drug resistance in ovarian cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cisplatin / pharmacology
  • Cisplatin / therapeutic use
  • Crystallography, X-Ray
  • Drug Design
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / metabolism
  • Enzyme Inhibitors / pharmacology*
  • Enzyme Inhibitors / therapeutic use
  • Female
  • Fluorouracil / pharmacology
  • Fluorouracil / therapeutic use
  • Humans
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Molecular Targeted Therapy*
  • Ovarian Neoplasms / drug therapy
  • Ovarian Neoplasms / enzymology*
  • Ovarian Neoplasms / pathology
  • Peptides / chemistry
  • Peptides / metabolism*
  • Peptides / pharmacology*
  • Peptides / therapeutic use
  • Protein Binding / drug effects
  • Protein Conformation
  • Protein Multimerization / drug effects
  • Thermodynamics
  • Thymidylate Synthase / antagonists & inhibitors*
  • Thymidylate Synthase / chemistry
  • Thymidylate Synthase / metabolism

Substances

  • Enzyme Inhibitors
  • Peptides
  • Thymidylate Synthase
  • Cisplatin
  • Fluorouracil