siRNA-mediated silencing of survivin inhibits proliferation and enhances etoposide chemosensitivity in acute myeloid leukemia cells.
BACKGROUND
Overexpression of survivin, a known inhibitor of apoptosis, is associated with tumor progression and drug resistance in numerous malignancies, including leukemias. The aim of this study was to investigate the effect of a specific survivin small interference RNA (siRNA) on proliferation and the sensitivity of HL-60 acute myeloid leukemia (AML) cells to the chemotherapeutic drug etoposide.


METHODS
The cells were transfected with siRNAs using LipofectamineTM2000 transfection reagent. Relative survivin mRNA and protein levels were measured by quantitative real-time PCR and Western blotting, respectively. Trypan blue exclusion assays were performed to monitor tumor cell proliferation after siRNA transfection. The cytotoxic effects of etoposide and survivin siRNA, alone and in combination, on leukemic cells were determined using MTT assay. Apoptosis was assessed by ELISA cell death assay.


RESULTS
Survivin siRNA markedly reduced both mRNA and protein expression levels in a time-dependent manner, leading to distinct inhibition of cell proliferation and increased spontaneous apoptosis. Surprisingly, survivin siRNA synergistically increased the cell toxic effects of etoposide. Moreover, survivin down-regulation significantly enhanced its induction of apoptosis.


CONCLUSIONS
Our study suggests that down-regulation of survivin by siRNA can trigger apoptosis and overcome drug resistance of leukemia cells. Therefore, survivin siRNA may be an effective adjuvant in AML chemotherapy.
Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran E-mail : baradaranb@tbzmed.ac.ir, esakhinia@yahoo.co.uk.
Hadi
H
Karami
Behzad
B
Baradaran
Ali
A
Esfahani
Mehrdad Asghari
MA
Estiar
Mohammad
M
Naghavi-Behzad
Masoud
M
Sakhinia
Ebrahim
E
Sakhinia
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005047:Etoposide / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077022:Survivin; D014407:Tumor Cells, Cultured
D000972:Antineoplastic Agents, Phytogenic; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000077022:Survivin; D005047:Etoposide