title: N-acetyl cysteine enhances imatinib-induced apoptosis of Bcr-Abl+ cells by endothelial nitric oxide synthase-mediated production of nitric oxide.
abstract: BACKGROUND
  Imatinib, a small-molecule inhibitor of the Bcr-Abl kinase, is a successful drug for treating chronic myeloid leukemia (CML). Bcr-Abl kinase stimulates the production of H(2)O(2), which in turn activates Abl kinase. We therefore evaluated whether N-acetyl cysteine (NAC), a ROS scavenger improves imatinib efficacy.
  
  
  METHODS
  Effects of imatinib and NAC either alone or in combination were assessed on Bcr-Abl(+) cells to measure apoptosis. Role of nitric oxide (NO) in NAC-induced enhanced cytotoxicity was assessed using pharmacological inhibitors and siRNAs of nitric oxide synthase isoforms. We report that imatinib-induced apoptosis of imatinib-resistant and imatinib-sensitive Bcr-Abl(+) CML cell lines and primary cells from CML patients is significantly enhanced by co-treatment with NAC compared to imatinib treatment alone. In contrast, another ROS scavenger glutathione reversed imatinib-mediated killing. NAC-mediated enhanced killing correlated with cleavage of caspases, PARP and up-regulation and down regulation of pro- and anti-apoptotic family of proteins, respectively. Co-treatment with NAC leads to enhanced production of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS). Involvement of eNOS dependent NO in NAC-mediated enhancement of imatinib-induced cell death was confirmed by nitric oxide synthase (NOS) specific pharmacological inhibitors and siRNAs. Indeed, NO donor sodium nitroprusside (SNP) also enhanced imatinib-mediated apoptosis of Bcr-Abl(+) cells.
  
  
  CONCLUSIONS
  NAC enhances imatinib-induced apoptosis of Bcr-Abl(+) cells by endothelial nitric oxide synthase-mediated production of nitric oxide.
authors.affiliation: The Department of Infectious Diseases & Immunology, Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Srabanti
authors.initials: S
authors.lastname: Rakshit
authors.forename: Jayashree
authors.initials: J
authors.lastname: Bagchi
authors.forename: Labanya
authors.initials: L
authors.lastname: Mandal
authors.forename: Kausik
authors.initials: K
authors.lastname: Paul
authors.forename: Dipyaman
authors.initials: D
authors.lastname: Ganguly
authors.forename: Sandip
authors.initials: S
authors.lastname: Bhattacharjee
authors.forename: Monidipa
authors.initials: M
authors.lastname: Ghosh
authors.forename: Nabendu
authors.initials: N
authors.lastname: Biswas
authors.forename: Utpal
authors.initials: U
authors.lastname: Chaudhuri
authors.forename: Santu
authors.initials: S
authors.lastname: Bandyopadhyay
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D017304:Annexin A5 / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001549:Benzamides; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D016166:Free Radical Scavengers / Q000494:pharmacology*; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism; D019337:Hematologic Neoplasms / Q000378:metabolism; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000187:drug effects / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011743:Pyrimidines / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000032:analysis; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D017304:Annexin A5; D001549:Benzamides; D016166:Free Radical Scavengers; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D000068877:Imatinib Mesylate; D052250:Nitric Oxide Synthase Type III; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; D000111:Acetylcysteine