Abstract | BACKGROUND: METHODS: Cell viability was measured using MTT assays. Apoptosis was measured by annexin V/PI dual staining and DNA fragmentation assays. Immunoblotting was performed to examine the expression of proteins. Colony assays were performed using methylcellulose. RESULTS: Treatment of CML cells with bortezomib results in downregulation of S-phase kinase protein 2 (SKP2) and concomitant stabilization of the expression of p27Kip1. Furthermore, knockdown of SKP2 with small interference RNA specific for SKP2 caused accumulation of p27Kip1. CML cells exposed to bortezomib leads to conformational changes in Bax protein, resulting in loss of mitochondrial membrane potential and leakage of cytochrome c to the cytosol. In the cytosol, cytochrome c causes sequential activation of caspase-9, caspase-3, PARP cleavage and apoptosis. Pretreatment of CML cells with a universal inhibitor of caspases, z-VAD-fmk, prevents bortezomib-mediated apoptosis. Our data also demonstrated that bortezomib treatment of CML downregulates the expression of inhibitor of apoptosis proteins. Finally, inhibition of proteasome pathways by bortezomib suppresses colony formation ability of CML cells. CONCLUSIONS: Altogether, these findings suggest that bortezomib suppresses the cell proliferation via induction of apoptosis in CML cells by downregulation of SKP2 with concomitant accumulation of p27Kip1, suggesting that proteasomal pathway may form novel therapeutic targets for better management of CML.
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Authors | Ahmad Iskandarani, Ajaz A Bhat, Kodappully S Siveen, Kirti S Prabhu, Shilpa Kuttikrishnan, Muzammil A Khan, Roopesh Krishnankutty, Michal Kulinski, Rihab R Nasr, Ramzi M Mohammad, Shahab Uddin |
Journal | Journal of translational medicine
(J Transl Med)
Vol. 14
Pg. 69
(Mar 09 2016)
ISSN: 1479-5876 [Electronic] England |
PMID | 26956626
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Antineoplastic Agents
- Proteasome Inhibitors
- S-Phase Kinase-Associated Proteins
- Ubiquitinated Proteins
- Bortezomib
- Caspases
- Proteasome Endopeptidase Complex
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Topics |
- Antineoplastic Agents
(pharmacology)
- Apoptosis
(drug effects)
- Bortezomib
(pharmacology)
- Caspases
(metabolism)
- Cell Cycle
(drug effects)
- Cell Line, Tumor
- Cell Proliferation
(drug effects)
- Down-Regulation
(drug effects)
- Enzyme Activation
(drug effects)
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive
(enzymology, pathology)
- Mitochondria
(drug effects, metabolism)
- Proteasome Endopeptidase Complex
(metabolism)
- Proteasome Inhibitors
(pharmacology)
- S-Phase Kinase-Associated Proteins
(metabolism)
- Ubiquitinated Proteins
(metabolism)
- Up-Regulation
(drug effects)
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