Down-regulation of telomerase activity and activation of caspase-3 are responsible for Tanshinone I-induced apoptosis in monocyte leukemia cells in vitro.
Tanshinone I (Tan-I) is a diterpene quinone extracted from the traditional herbal medicine Salvia miltiorrhiza Bunge. Recently, Tan-I has been reported to have anti-tumor effects. In this study, we investigated the growth inhibition and apoptosis inducing effects of Tan-I on three kinds of monocytic leukemia cells (U937, THP-1 and SHI 1). Cell viability was measured by MTT assay. Cell apoptosis was assessed by flow cytometry (FCM) and AnnexinV/PI staining. Reverse transcriptase polymerase chain reaction (RT-PCR) and PCR-enzyme-linked immunosorbent assay (ELISA) were used to detect human telomerase reverse transcriptase (hTERT) expression and telomerase activity before and after apoptosis. The activity of caspase-3 was determined by Caspase colorimetric assay kit and Western blot analysis. Expression of the anti-apoptotic gene Survivin was assayed by Western blot and Real-time RT-PCR using the ABI PRISM 7500 Sequence Detection System. The results revealed that Tan-I could inhibit the growth of these three kinds of leukemia cells and cause apoptosis in a time- and dose-dependent manner. After treatment by Tan-I for 48 h, Western blotting showed cleavage of the caspase-3 zymogen protein with the appearance of its 17-kD subunit, and a 89-kD cleavage product of poly (ADP-ribose) polymerase (PARP), a known substrate of caspase-3, was also found clearly. The expression of hTERT mRNA as well as activity of telomerase were decreased concurrently in a dose-dependent manner. Moreover, Real-time RT-PCR and Western blot revealed a significant down-regulation of Survivin. We therefore conclude that the induction of apoptosis by Tan-I in monocytic leukemia U937 THP-1 and SHI 1 cells is highly correlated with activation of caspase-3 and decreasing of hTERT mRNA expression and telomerase activity as well as down-regulation of Survivin expression. To our knowledge, this is the first report about the effects of Tan-I on monocytic leukemia cells.
Liu
Xiao-Dan
XD
Hematological Department & Institute, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, China; E-Mails: lenovo381@126.com (X.-D.L.); xfangcn@163.com (R.-F.F.); fzg92@163.com (Z.-G.F.); dongjunlin0168@163.com (D.-J.L.); ruozhi_xiao@yahoo.com (R.-Z.X.); huangrw56@163.com (R.-W.H.).
Fan
Rui-Fang
RF
Zhang
Yong
Y
Yang
Hong-Zhi
HZ
Fang
Zhi-Gang
ZG
Guan
Wei-Bing
WB
Lin
Dong-Jun
DJ
Xiao
Ruo-Zhi
RZ
Huang
Ren-Wei
RW
Huang
He-Qing
HQ
Liu
Pei-Qing
PQ
Liu
Jia-Jun
JJ
D045784:Abietanes / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000378:metabolism; D000077022:Survivin; D019098:Telomerase / Q000378:metabolism*; D020298:U937 Cells
D045784:Abietanes; D000972:Antineoplastic Agents, Phytogenic; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D000077022:Survivin; C021751:tanshinone; D019098:Telomerase; D053148:Caspase 3