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ANEES RAHMAN CHERATTA
Department of Biochemistry
College of Medicine and Health Sciences
Title
A study on sanguinarine as an antileukemic agent– involvement of reactive oxygen
species-ceramide-Akt apoptotic signaling pathway
Faculty Advisor
Prof. Sehamuddin Galadari
Defense Date
03 March 2016
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. The main objective
of this dissertation was to examine the antileukemic effect of sanguinarine, in vitro, and to further examine
the signaling mechanisms that may be involved. This study demonstrates that in human leukemic cells,
sanguinarine activates a caspase-dependent apoptotic cell death pathway that is characterized by reactive
oxygen species-dependent ceramide generation, and subsequent inhibition of Akt signaling pathway. In
addition, sanguinarine also induces reactive oxygen species-dependent glutathione depletion and activation
of extracellular signal-regulated kinase12/. Moreover, inhibition of reactive oxygen species generation,
using reactive oxygen species scavengers and antioxidants, significantly abrogates sanguinarine-induced
ceramide generation, Akt dephosphorylation, extracellular signal-regulated kinase12/ activation, and
apoptosis. Sanguinarine-induced ceramide generation is mediated via reactive oxygen species-dependent
activation of acid sphingomyelinase in Jurkat cells and inhibition of acid ceramidase and glucosylceramide
synthase in both Jurkat and Molt-4 cells. Furthermore, the involvement of ceramide-activated protein
phosphatase-1 in sanguinarine-induced Akt dephosphorylation and apoptosis is demonstrated. Altogether,
this study underscores the critical role for reactive oxygen species-ceramide-Akt signaling pathway and
reactive oxygen species-dependent extracellular signal-regulated kinase12/ activation in the antileukemic
action of sanguinarine. Understanding the molecular signaling mechanism of sanguinarine-induced
apoptosis undoubtedly should have a great impact on future sanguinarine-based antileukemic drug
development.
Dissertation