Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

Induction of Apoptosis by Methyl Alcohol Extract of Enteromorpha linza (Linnaeus) J Agardh in U937 Human Leukemia Cells

Eun-Ok Choi¹, Hyang-Suk Kim^1,3, Min-Ho Han², Cheol Park⁴, Byung-Woo Kim^1,2,5, Jin Ah Hwang⁶, Yung Hyun Choi^1,2,7 , Hye-Jin Hwang^1,2,3

¹Anti-Aging Research Center; ²Blue-Bio Industry RIC, Departments of; ³Food and Nutrition; ⁴Molecular Biology, and; ⁵Life Science and Biotechnology, Dongeui University Busan 614-714; ⁶Department of Food and Nutrition, Myongji University, Gyeonggi-do, 449-728; ⁷Department of Biochemistry, Dongeui University College of Oriental Medicine, Busan 614-052, Republic of Korea.

For correspondence:- Yung Choi Email: choiyh@deu.ac.kr Tel:+82518507413

Received: 23 July 2013 Accepted: 4 April 2014 Published: 26 June 2014

Citation: Choi E, Kim H, Han M, Park C, Kim B, Hwang JA, et al. Induction of Apoptosis by Methyl Alcohol Extract of Enteromorpha linza (Linnaeus) J Agardh in U937 Human Leukemia Cells. Trop J Pharm Res 2014; 13(6):881-888 doi: 10.4314/tjpr.v13i6.8

© 2014 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..

Abstract

Purpose: To investigate the anti-cancer effect of methyl alcohol extract of Enteromorpha linza (Linnaeus) J. Agardh (MEEL) in U937 human leukemia cells.

Methods: Cytotoxicity was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Apoptosis was detected using 4',6-diamidino-2-phenylindole (DAPI) staining, agarose gel electrophoresis, and flow cytometry. Protein levels were determined by Western blot analysis. Caspase activity was measured spectrophotometrically at 405 nm.

Results: MEEL inhibited U937 cell proliferation and induced apoptosis through up-regulation of death receptor-related gene expression, caspase-8 activation and truncation of Bid, which was associated with the loss of mitochondrial membrane potential. Subsequently, the levels of anti-apoptotic proteins such as Bcl-2 and Bcl-xL, and IAP family proteins decreased but those of pro-apoptotic proteins including Bax and Bad increased in MEEL-treated U937 cells. MEEL treatment also resulted in activation of caspase-9 and -3 as well as concomitant cleavage of poly(ADP-ribose) polymerase and phopholipase Cγ-1. However, pretreatment of U937 cells with z-VAD-fmk, a pan caspase inhibitor, abrogated chromatin condensation and DNA fragmentation and prevented cell death induced by the MEEL.

Conclusion: The findings suggest that MEEL induced apoptosis in U937 cells through a signaling cascade of death-receptor-mediated extrinsic as well as mitochondria-mediated intrinsic pathways, thus raising the possibility that MEEL may be of value in the development of novel therapeutic approaches for treating leukemia.

Keywords: Enteromorpha linza, Apoptosis, Caspase, U937 cells