title: 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.
abstract: 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.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, 308 Harvard Street SE, Minneapolis, MN 55455, USA.
authors.forename: Jignesh M
authors.initials: JM
authors.lastname: Doshi
authors.forename: Defeng
authors.initials: D
authors.lastname: Tian
authors.forename: Chengguo
authors.initials: C
authors.lastname: Xing
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D001578:Benzopyrans / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells; D008175:Lung Neoplasms / Q000188:drug therapy; D009570:Nitriles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured / Q000187:drug effects; D051020:bcl-X Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C491073:BCL2L2 protein, human; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; C456800:ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate; D002945:Cisplatin