Expression of survivin gene in apoptosis induced by dexamethasone in CEM cells.
OBJECTIVE
The precise mechanism of glucocorticoid-induced apoptosis has not yet been elucidated. Survivin, a member of the inhibitors of apoptosis protein family, correlates with inhibition of apoptosis, proliferation, angiogenesis and multiple drugs resistance. This study aimed to investigate the variation of the survivin gene expression in apoptosis induced by dexamethasone (Dex) in the human T-lineage acute lymphoblastic leukemia (ALL) cell line, CEM-WT cells.


METHODS
The logarithmically growing CEM cells cultured in vitro (cell density 2 x10(5)/mL) were exposed to 0.1, 0.5, 1, 5, and 10 microM Dex, then were collected 24, 48 and 72 hrs later. Untreated CEM cells were used as Controls. The cell viability was determined by trypan blue dye exclusion. Apoptosis was evaluated by morphology and flow cytometry. Survivin protein and gene were analyzed by Western Blot and RT-PCR.


RESULTS
CEM cells growth was obviously inhibited by 0.1, 0.5, 1, 5, and 10 microM Dex from 48 hrs. The inhibition effect was dose- and time-dependent. CEM cells treated with Dex (> or = 5 microM) exhibited typical apoptotic features. The apoptosis increased after 5 microM Dex treatment in a time-dependent manner, with the apoptosis percentage increasing from 14.9% (12 hrs) to 46.2% (48 hrs). Compared with that of the Control group, the expression of survivin protein was down-regulated, with the expression rate of 54.6%, 45.5%, 15.8% and 9.7% respectively at 12, 24, 48 and 72 hrs after 5 microM Dex treatment. 5 microM Dex treatment also resulted in a decrease of survivin mRNA expression. The survivin mRNA expression was 76.4%, 67.3%, 55.0%, 49.9%, 38.3% and 18.3% of the Control respectively at 6, 12, 24, 48 and 72 hrs after Dex treatment.


CONCLUSIONS
Apoptosis induced by Dex in CEM cells is associated with downregulation of the survivin expression.
He
Li
L
Department of Pediatrics, First Hospital of China Medical University, Shenyang 110001, China. hlcmu@yahoo.com.cn
Liu
Yun-Peng
YP
Hou
Ke-Zuo
KZ
Li
Dan
D
Zhu
Zhi-Tu
ZT
Zhang
Jing-Dong
JD
D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D003907:Dexamethasone / Q000494:pharmacology*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000378:metabolism* / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000235:genetics*; D009363:Neoplasm Proteins / Q000032:analysis / Q000235:genetics*; D000077022:Survivin
C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D000077022:Survivin; D003907:Dexamethasone