Manipulation Of Redox Status Of Chronic Myeloid Leukemic Cells That Favours Apoptosis
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
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| Title |
Manipulation Of Redox Status Of Chronic Myeloid Leukemic Cells That Favours Apoptosis
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| Creator |
Chowdhury, Avik Acharya
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| Subject |
Infectious Diseases and Immunology
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| Description |
Redox status refers to the balance between pro-oxidant and anti-oxidant level in cells. Cancer cells exhibit multiple genetic alterations and high oxidative stress. Therefore, it might be possible to preferentially eliminate these cells by pharmacological ROS insults. However, the
up regulation of antioxidant capacity in adaptation to intrinsic oxidative stress in cancer cells can confer drug resistance. Modulation of the redox mechanisms of cancer cells might be an effective strategy to eliminate these cells. Hydroxychavicol (HCH), a constituent of Piper
betel leaves, has potent anti-chronic myeloid leukemia (CML) activity. HCH causes apoptosis of CML cells by induction of reactive oxygen species (ROS). Here we manipulated the threshold of intracellular ROS by depleting intracellular glutathione, a key antioxidant in cells, using combined treatment with buthionine sulfoximine (BSO), an inhibitor of gammaglutamylcysteine
synthetase, a rate limiting enzyme in glutathione biosynthesis, and nonapoptotic doses of HCH. BSO significantly potentiated apoptosis-inducing activity of HCH in leukemic cells by caspase-dependent as well as caspase-independent but apoptosis inducing
factor (AIF)-dependent manner. Enhanced depletion of intracellular GSH induced by combined treatment correlated with induction of ROS. Activation of ROS- dependent JNK
played a crucial role in ERK1/2 activation which subsequently induced the expression of inducible nitric oxide synthase (iNOS). iNOS-mediated production of nitric oxide (NO) was identified as an effector molecule causing apoptosis of CML cells. Treatment with BSO plus
HCH significantly induced G2/M phase arrest through down regulation of cyclin B1, inhibitory phosphorylations of cdc2 and cdc25C. We also found increased phosphorylation of
ATM and Chk2 time dependently without any effect on Chk1. Furthermore, treatment with ATM inhibitor caffeine and Chk2 inhibitor attenuated G2/M arrest and their downstream
signaling molecules. Restoration of intracellular GSH pool correlated with ATM dephosphorylation. Our results showed that ATM- and Chk2-mediated inhibitory phosphorylation of cdc25C plays a major role in G2/M arrest. We also observed that BSO plus HCH- induced cell cycle arrest was not restricted to p53 status in human leukemia cells.
This combined treatment merits further testing in pre-clinical settings.
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| Date |
2014
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| Type |
Thesis
NonPeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/2057/1/Avik_Acharya_Chowdhury%2C_Ph.D._Thesis.pdf
Chowdhury, Avik Acharya (2014) Manipulation Of Redox Status Of Chronic Myeloid Leukemic Cells That Favours Apoptosis. PhD thesis, Calcutta University. |
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| Relation |
http://www.eprints.iicb.res.in/2057/
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