title: Induction of ROS-independent JNK-activation-mediated apoptosis by a novel coumarin-derivative, DMAC, in human colon cancer cells.
abstract: In this study, we investigated the antitumor activity of a novel coumarin derivative, 5,7-dihydroxy-4-methyl-6-(3-methylbutanoyl)-coumarin (DMAC), on colorectal carcinoma. DMAC treatment resulted in substantial proapoptotic activity against colon cancer HCT116 and LoVo cells. Induction of apoptotic characteristics, including cellular shrinkage, chromatin condensation, and Annexin V detection, was observed following DMAC treatment. Mechanistically, we observed that DMAC elicited induction of proteolytic cascade activation including cleavage of caspase-3 and poly ADP-ribose polymerase (PARP) expression and loss of the antiapoptotic proteins, Mcl-1 and Bcl-XL, accompanied by an increase in expression of the proapoptotic protein, Bak. In addition, suppressing c-Jun N-terminal protein kinase (JNK), but not extracellular-regulated protein kinase (ERK) or p38, substantially diminished DMAC-induced cell death and caspase-3 and PARP cleavage. However, pretreatment with antioxidants, including N-acetyl-l-cysteine (NAC) and diphenylene iodonium (DPI), failed to protect against DMAC-elicited apoptosis. Pretreatment with the JNK inhibitor, SP600125, suppressed DMAC-induced JNK phosphorylation, which was accompanied by a reversal of Bcl-XL expression. Moreover, combining DMAC treatment with the conventional anticancer drugs, 5-FU and CPT-11, considerably enhanced their therapeutic efficacies. Structural-activity relationship analyses further revealed that an alkylation substitution at position 6 of the coumarin ring was critical for inducing apoptosis, and the phenyl group at position 4 might have enhanced its bioactivity. Our data showed that DMAC can be used as part of a promising strategy to enhance therapeutic efficacies, and could be used to develop an approach for structure-based drug design for cancer treatment.
authors.affiliation: Graduate Institute of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Mei-Hsiang
authors.initials: MH
authors.lastname: Lin
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chia-Hsiung
authors.initials: CH
authors.lastname: Cheng
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ku-Chung
authors.initials: KC
authors.lastname: Chen
authors.affiliation: Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wai-Theng
authors.initials: WT
authors.lastname: Lee
authors.affiliation: Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yen-Fang
authors.initials: YF
authors.lastname: Wang
authors.affiliation: Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Cai-Qin
authors.initials: CQ
authors.lastname: Xiao
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. Electronic address: cwlin@tmu.edu.tw.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Lin
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001152:Arsenicals / Q000737:chemistry / Q000494:pharmacology*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms; D003374:Coumarins / Q000737:chemistry; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015394:Molecular Structure; D017382:Reactive Oxygen Species
chemical_list: D000970:Antineoplastic Agents; D001152:Arsenicals; D003374:Coumarins; D017382:Reactive Oxygen Species; C587955:dimethylarsino-cysteine; C030123:coumarin; D048031:JNK Mitogen-Activated Protein Kinases; D003545:Cysteine
keywords: Apoptosis; Coumarin; MAPK; Reactive oxygen species