Inactivation of PI3k/Akt signaling pathway and activation of caspase-3 are involved in tanshinone I-induced apoptosis in myeloid leukemia cells in vitro.
Tanshinone I (Tan I), a diterpene quinone extracted from herbal medicine Salvia miltiorrhiza Bunge, has recently been reported to have antitumor effects. As the mechanism of its proapoptotic effects on human myeloid leukemia cells has not been extensively studied, we performed an in-depth evaluation of the effects of Tan I on apoptosis in human K562 and HL-60 cells. The results revealed that Tan I could inhibit the growth of leukemia cells and cause apoptosis in a time- and dose-dependent manner. Apoptosis was observed clearly by flow cytometry and Hoechst 33258 staining, as well as DNA fragmentation analysis. After treatment by Tan I for 48 h, the percentage of disruption of mitochondrial membrane potential (Δψm) was increased in a dose-dependent manner. Western blotting analysis demonstrated the cleavage of caspase-3 zymogen protein and a dose-dependent cleavage of poly-(ADP-ribose) polymerase. Tan I-induced apoptosis was accompanied by a significant decrease in survivin and an increase in Bax. Moreover, Tan I treatment remarkably downregulated the phosphorylation of both P85/PI3K and Akt in a time-dependent manner, and the PI3K/AKT-specific inhibitor (LY294002) mimicked the apoptosis-inducing effects of Tan I. We therefore conclude that the induction of apoptosis by Tan I in these leukemia cells is mainly related to the disruption of Δψm, the upregulation of Bax expression, and the activation of caspase-3. This process is highly correlated with the inactivation of PI3K/Akt/survivin signaling pathways. The results indicate that Tan I may serve as an effective adjunctive reagent in the treatment of leukemia.
Hematological Department and Institute, Third Hospital of Sun Yat-Sen University, Guangzhou, People's Republic of China. jiajunliu2002@yahoo.com.cn
Jia-Jun
JJ
Liu
Wen-Da
WD
Liu
Hong-Zhi
HZ
Yang
Yong
Y
Zhang
Zhi-Gang
ZG
Fang
Pei-Qing
PQ
Liu
Dong-Jun
DJ
Lin
Ruo-Zhi
RZ
Xiao
Yuan
Y
Hu
Chun-Zhi
CZ
Wang
Xu-Dong
XD
Li
Yi
Y
He
Ren-Wei
RW
Huang
D045784:Abietanes; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism*; D053938:DNA Fragmentation / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D004789:Enzyme Activation; D018922:HL-60 Cells / Q000187:drug effects; D006801:Humans; D020014:K562 Cells / Q000187:drug effects; D007951:Leukemia, Myeloid / Q000378:metabolism / Q000503:physiopathology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D015394:Molecular Structure; D010616:Phenanthrenes / Q000737:chemistry / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
D045784:Abietanes; D000972:Antineoplastic Agents, Phytogenic; D053148:Caspase 3; D004365:Drugs, Chinese Herbal; D010616:Phenanthrenes; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C021751:tanshinone