title: Hydrogen peroxide/ceramide/Akt signaling axis play a critical role in the antileukemic potential of sanguinarine.
abstract: Dysregulation of apoptosis is a prime hallmark of leukemia. Therefore, drugs which restore the sensitivity of leukemic cells to apoptotic stimuli are promising candidates in the treatment of leukemia. Recently, we have demonstrated that sanguinarine (SNG), a benzophenanthridine alkaloid, isolated from Sanguinaria canadensis induces ROS-dependent ERK1/2 activation and autophagic cell death in human malignant glioma cells (Pallichankandy et al., 2015; [43]). In this study, we investigated the antileukemic potential of SNG in vitro, and further examined the molecular mechanisms of SNG-induced cell death. In human leukemic cells, SNG activated apoptotic cell death pathway characterized by activation of caspase cascade, DNA fragmentation and down-regulation of anti-apoptotic proteins. Importantly, we have identified a crucial role for hydrogen peroxide (H2O2)-dependent ceramide (Cer) generation in the facilitation of SNG-induced apoptosis. Additionally, we have found that SNG inhibits Akt, a key anti-apoptotic protein kinase by dephosphorylating it at Ser(473), leading to the dephosphorylation of its downstream targets, GSK3β and mTOR. Interestingly, inhibition of Cer generation, using acid sphingomyelinase inhibitor, significantly reduced the SNG-induced Akt dephosphorylation and apoptosis, whereas, activation of Cer generation using inhibitors of acid ceramidase and glucosylceramide synthase enhanced it. Furthermore, using a group of ceramide activated protein phosphatases (CAPPs) inhibitor (calyculin A, Okadaic acid, and phosphatidic acid), the involvement of protein phosphatase 1 form of CAPP in SNG-induced Akt dephosphorylation and apoptosis was demonstrated. Altogether, these results underscore a critical role for H2O2-Cer-Akt signaling axis in the antileukemic action of SNG.
authors.affiliation: Cell Signaling Laboratory, Department of Biochemistry, College of Medicine and Health Sciences, UAE University, P.O. Box 17666, Al Ain, Abu Dhabi, United Arab Emirates. Electronic address: anees@uaeu.ac.ae.
authors.forename: Anees
authors.initials: A
authors.lastname: Rahman
authors.affiliation: Cell Signaling Laboratory, Department of Biochemistry, College of Medicine and Health Sciences, UAE University, P.O. Box 17666, Al Ain, Abu Dhabi, United Arab Emirates. Electronic address: t.faisal@uaeu.ac.ae.
authors.forename: Faisal
authors.initials: F
authors.lastname: Thayyullathil
authors.affiliation: Cell Signaling Laboratory, Department of Biochemistry, College of Medicine and Health Sciences, UAE University, P.O. Box 17666, Al Ain, Abu Dhabi, United Arab Emirates. Electronic address: sirajpk@uaeu.ac.ae.
authors.forename: Siraj
authors.initials: S
authors.lastname: Pallichankandy
authors.affiliation: Cell Signaling Laboratory, Department of Biochemistry, College of Medicine and Health Sciences, UAE University, P.O. Box 17666, Al Ain, Abu Dhabi, United Arab Emirates; Al Jalila Foundation Research Centre, P.O. Box 300100, Dubai, United Arab Emirates. Electronic address: sehamuddin@uaeu.ac.ae.
authors.forename: Sehamuddin
authors.initials: S
authors.lastname: Galadari
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053119:Benzophenanthridines / Q000008:administration & dosage*; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D000071679:Glycogen Synthase Kinase 3 beta / Q000235:genetics*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007546:Isoquinolines / Q000008:administration & dosage*; D007938:Leukemia / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D051058:Oncogene Protein v-akt / Q000235:genetics* / Q000378:metabolism; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000235:genetics*
chemical_list: D053119:Benzophenanthridines; D002518:Ceramides; D007546:Isoquinolines; D017382:Reactive Oxygen Species; C065576:ceramide 1-phosphate; C005705:sanguinarine; D006861:Hydrogen Peroxide; C546842:MTOR protein, human; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051058:Oncogene Protein v-akt; D058570:TOR Serine-Threonine Kinases
keywords: Akt; Apoptosis; Ceramide; Hydrogen peroxide; Sanguinarine