Structure-activity relationship studies of ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (HA 14-1), an antagonist for antiapoptotic Bcl-2 proteins to overcome drug resistance in cancer

J Med Chem. 2006 Dec 28;49(26):7731-9. doi: 10.1021/jm060968r.


The structure-activity relationship studies of ethyl 2-amino-6-cyclopentyl-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (1, HA 14-1), an antagonist of the antiapoptotic Bcl-2 proteins, are reported. A series of analogues of 1 with varied functional groups at the 6-position of the chromene ring were synthesized. These candidates were evaluated for their binding interactions with three antiapoptotic proteins: Bcl-2, Bcl-XL, and Bcl-w. They were also assayed for their in vitro cytotoxicities against a set of Jurkat cells with varied levels of Bcl-2 and Bcl-XL proteins and a non-small-cell lung carcinoma cell line (NCI-H460). It was found that the 6-bromo of 1 was not essential for its bioactivity and the 6-position can accommodate a variety of alkyl groups. 1 and its analogues bind to all of the three antiapoptotic Bcl-2 proteins tested. Positive correlations were observed between the binding affinities of these candidates to the antiapoptotic Bcl-2 proteins and their in vitro cytotoxicities, suggesting that the antiapoptotic Bcl-2 proteins are likely to be the cellular targets of 1 and its analogues. (In this study, the binding interactions of the small molecules to antiapoptotic Bcl-2 proteins were studied by assaying their abilities to compete against a Bak peptide binding to the antiapoptotic Bcl-2 proteins. Inhibitory constants, instead of dissociation constants, were obtained in such assays. The term "binding affinity" is used in this article for simplicity.) The most active compound, 3g, had a >3-fold increase of binding affinity to the antiapoptotic Bcl-2 proteins and a >13-fold increase of in vitro cytotoxicity over 1. Though Jurkat cells with transgenic overexpression of Bcl-2 or Bcl-XL protein can develop resistance to standard cancer therapies, such cells failed to develop resistance to 1 based candidates. 1 also sensitizes Jurkat cells to cisplatin. These studies provide further support that 1 and its analogues function as antagonists for antiapoptotic Bcl-2 proteins and that they have the potential, either as a single agent or as a combination therapy with other anticancer agents, to treat cancers with the overexpression of antiapoptotic Bcl-2 proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects
  • Apoptosis Regulatory Proteins / antagonists & inhibitors*
  • Apoptosis Regulatory Proteins / metabolism
  • Benzopyrans / chemical synthesis
  • Benzopyrans / chemistry
  • Benzopyrans / pharmacology*
  • Carcinoma, Non-Small-Cell Lung / drug therapy
  • Cisplatin / pharmacology
  • Drug Resistance, Neoplasm*
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Jurkat Cells
  • Lung Neoplasms / drug therapy
  • Nitriles / chemical synthesis
  • Nitriles / chemistry
  • Nitriles / pharmacology*
  • Proto-Oncogene Proteins c-bcl-2 / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Structure-Activity Relationship
  • Tumor Cells, Cultured / drug effects
  • bcl-X Protein / antagonists & inhibitors*
  • bcl-X Protein / metabolism


  • Antineoplastic Agents
  • Apoptosis Regulatory Proteins
  • BCL2L2 protein, human
  • Benzopyrans
  • Enzyme Inhibitors
  • Nitriles
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-X Protein
  • ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate
  • Cisplatin