Dual mechanisms of sHA 14-1 in inducing cell death through endoplasmic reticulum and mitochondria. Mol Pharmacol 2009 Sep;76(3):667-78
Date
06/30/2009Pubmed ID
19561125Pubmed Central ID
PMC2730395DOI
10.1124/mol.109.055830Scopus ID
2-s2.0-69549124714 (requires institutional sign-in at Scopus site) 46 CitationsAbstract
HA 14-1 is a small-molecule Bcl-2 antagonist that promotes apoptosis in malignant cells, but its mechanism of action is not well defined. We recently reported that HA 14-1 has a half-life of only 15 min in vitro, which led us to develop a stable analog of HA 14-1 (sHA 14-1). The current study characterizes its mode of action. Because of the antiapoptotic function of Bcl-2 family proteins on the endoplasmic reticulum (ER) and mitochondria, the effect of sHA 14-1 on both organelles was evaluated. sHA 14-1 induced ER calcium release in human leukemic cells within 1 min, followed by induction of the ER stress-inducible transcription factor ATF4. Similar kinetics and stronger intensity of ER calcium release were induced by the sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibitor thapsigargin, accompanied by similar kinetics and intensity of ATF4 induction. sHA 14-1 directly inhibited SERCA enzymatic activity but had no effect on the inositol triphosphate receptor. Evaluation of the mitochondrial pathway showed that sHA 14-1 triggered a loss of mitochondrial transmembrane potential (Delta psi m) and weak caspase-9 activation, whereas thapsigargin had no effect. (R)-4-(3-Dimethylamino-1-phenylsulfanylmethyl-propylamino)-N-{4-[4-(4'-chloro-biphenyl-2-ylmethyl)-piperazin-1-yl]-benzoyl}-3-nitrobenzenesulfonamide (ABT-737), a well established small-molecule Bcl-2 antagonist, rapidly induced loss of Delta psi m and caspase-9 activation but had no effect on the ER. The pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone had some protective effect on sHA 14-1-induced cell death. These collective results suggest a unique dual targeting mechanism of sHA 14-1 on the apoptotic resistance machinery of tumor cells that includes antiapoptotic Bcl-2 family proteins and SERCA proteins.
Author List
Hermanson D, Addo SN, Bajer AA, Marchant JS, Das SG, Srinivasan B, Al-Mousa F, Michelangeli F, Thomas DD, Lebien TW, Xing CAuthor
Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
ApoptosisBenzopyrans
Cell Line, Tumor
Endoplasmic Reticulum
Humans
Mitochondria
Nitriles
Proto-Oncogene Proteins c-bcl-2
Sarcoplasmic Reticulum Calcium-Transporting ATPases