Abstract 4608: Hydrogen sulfide-releasing aspirin inhibits the growth of leukemic Jurkat cells and modulates β-catenin expression

Abstract

Abstract Introduction: Acute leukemia is the primary cause of cancer-related mortality in children. ß -catenin, a regulator of cell-cell adhesion and transcription, is expressed in T-acute lymphoblastic leukemia cells, tumor lines of hematopoietic origin and primary leukemia cells but not in normal peripheral blood T cells. ß -catenin may promote leukemia cell proliferation, adhesion, and survival. Hydrogen sulfide-releasing aspirin (HS-ASA) is a novel compound with significant potential for the control of cancer. It consists of a traditional ASA molecule covalently bound to an H2S-releasing moiety (5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione). Here we examined the effect of HS-ASA on the growth of Jurkat T-acute lymphoblastic leukemia cells and on the fate of ß -catenin. Methods: HS-ASA was synthesized and purified at our lab with 1H-NMR verification. Cell line: Jurkat T-leukemia. Quantification of cell growth: MTT assay. Cell kinetics: cell cycle phase distribution by flow cytometry; apoptosis by subdiploid (sub-G0/G1) peak in DNA content histograms; and proliferation by PCNA. ß-Catenin and caspase-3 expression was assayed by immunoblotting in cells treated with HS-ASA at 24 hr. Caspase-3 enzyme activity, and H2S levels was also measured. Results: 1) The IC50 for HS-ASA was 1.5 ± 0.2 µM, whereas that of ASA was >5000 µM strongly suggesting that HS-ASA is at least 3000-fold more potent than traditional ASA. 2) At 0.5xIC50, 1xIC50, and 2xIC50 the following observations were made: Proliferation was inhibited by 88 ± 2%, 63 ± 2%, 42 ± 3%; apoptosis was increased by 15 ± 2%, 39 ± 3%, 54 ± 4%; and cells in the G0/G1 phase increased dose-dependently whereas those in the S and G2/M phases decreased, suggesting a G0/G1 block. 3) HS-ASA dose-dependently reduced the levels of ß-catenin, whereas ASA up to 5 mM had no effect on ß-catenin expression. HS-ASA also increased caspase-3 protein levels and increased its activity dose-dependently, at 0 (no treatment), 0.5xIC50, 1xIC50, and 2xIC50 the values were 3.9 ± 0.3, 12.3 ± 0.5, 23.3 ± 0.7, and 42.6 ± 1.2 pmol/min/mg protein. H2S levels also increased as a function of HS-ASA concentration. Conclusion: HS-ASA strongly inhibits the growth of Jurkat T cells and causes inhibition of ß-catenin expression. These studies suggest one mechanism by which HS-ASA inhibits the growth of Jurkat T cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4608. doi:10.1158/1538-7445.AM2011-4608