title: Apoptotic effects of mahanine on human leukemic cells are mediated through crosstalk between Apo-1/Fas signaling and the Bid protein and via mitochondrial pathways.
abstract: Apo-1 (Fas/CD95), a cell surface receptor, triggers apoptosis after binding to its physiological ligand, Apo-1L (FasL/CD95L). This study reports that mahanine, purified from the leaves of Murraya koenigii, has a dose- and time-dependent anti-proliferative activity in acute lymphoid (MOLT-3) and chronic myeloid (K562) leukemic cell lines and in the primary cells of leukemic and myeloid patients, with minimal effect on normal immune cells including CD34(+) cells. Leukemic cells underwent phosphatidylserine externalization and DNA fragmentation, indicating mahanine-induced apoptosis. An increase in reactive oxygen species suggests that the mahanine-induced apoptosis was mediated by oxidative stress. A significant drop in the Bcl2/Bax ratio, the loss of mitochondrial transmembrane potential as well as cytochrome c release from the mitochondria to the cytosol suggested involvement of the mitochondrial pathway of apoptosis. Cytochrome c release was followed by the activation of caspase-9, caspase-3 and caspase-7, and cleavage of PARP in both MOLT-3 and K562 cells. In MOLT-3 cells, formation of the Fas-FasL-FADD-caspase-8 heterotetramer occurred, leading to the cleavage of Bid to its truncated form, which consequently resulted in formation of the mitochondrial transmembrane pore. The incubation of MOLT-3 cells with mahanine in the presence of caspase-8 inhibitor or FasL-neutralizing NOK-2 antibody resulted in the decrease of mahanine-induced cell death. Mahanine was also a potent inhibitor of K562 xenograft growth, which was evident in an athymic nude mice model. In summary, these results provide evidence for involvement of the death receptor-mediated extrinsic pathway of apoptosis in the mahanine-induced anticancer activity in MOLT-3 cells, but not in K562 cells, which are deficient in Fas/FasL.
authors.affiliation: Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, A Unit of Council of Scientific and Industrial Research, 4, Raja S.C. Mullick Road, Kolkata 700032, India.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Bhattacharya
authors.forename: Suman K
authors.initials: SK
authors.lastname: Samanta
authors.forename: Rakshamani
authors.initials: R
authors.lastname: Tripathi
authors.forename: Asish
authors.initials: A
authors.lastname: Mallick
authors.forename: Sarmila
authors.initials: S
authors.lastname: Chandra
authors.forename: Bikas C
authors.initials: BC
authors.lastname: Pal
authors.forename: Chandrima
authors.initials: C
authors.lastname: Shaha
authors.forename: Chitra
authors.initials: C
authors.lastname: Mandal
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism*; D002227:Carbazoles / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D020014:K562 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves; D020239:Receptor Cross-Talk / Q000187:drug effects* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D023041:Xenograft Model Antitumor Assays / Q000379:methods; D019014:fas Receptor / Q000502:physiology*
chemical_list: D000470:Alkaloids; D000972:Antineoplastic Agents, Phytogenic; D051023:BH3 Interacting Domain Death Agonist Protein; D002227:Carbazoles; D010936:Plant Extracts; D019014:fas Receptor; C465290:mahanine