Dual small-molecule targeting of procaspase-3 dramatically enhances zymogen activation and anticancer activity

J Am Chem Soc. 2014 Jan 29;136(4):1312-9. doi: 10.1021/ja4124303. Epub 2014 Jan 16.


Combination anticancer therapy typically consists of drugs that target different biochemical pathways or those that act on different targets in the same pathway. Here we demonstrate a new concept in combination therapy, that of enzyme activation with two compounds that hit the same biological target, but through different mechanisms. Combinations of procaspase-3 activators PAC-1 and 1541B show considerable synergy in activating procaspase-3 in vitro, stimulate rapid and dramatic maturation of procaspase-3 in multiple cancer cell lines, and powerfully induce caspase-dependent apoptotic death to a degree well exceeding the additive effect. In addition, the combination of PAC-1 and 1541B effectively reduces tumor burden in a murine lymphoma model at dosages for which the compounds alone have minimal or no effect. These data suggest the potential of PAC-1/1541B combinations for the treatment of cancer and, more broadly, demonstrate that differentially acting enzyme activators can potently synergize to give a significantly heightened biological effect.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / chemistry
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Apoptosis / drug effects
  • Caspase 3 / metabolism*
  • Cell Proliferation / drug effects
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Enzyme Activation / drug effects
  • HL-60 Cells
  • Humans
  • Hydrazones / chemistry
  • Hydrazones / pharmacology*
  • Lymphoma / drug therapy*
  • Lymphoma / pathology
  • Mice
  • Mice, Inbred C57BL
  • Molecular Structure
  • Piperazines / chemistry
  • Piperazines / pharmacology*
  • Structure-Activity Relationship
  • Tumor Cells, Cultured


  • (4-benzylpiperazin-1-yl)acetic acid (3-allyl-2-hydroxybenzylidene)hydrazine
  • Hydrazones
  • Piperazines
  • Caspase 3