Induction of G2/M arrest, endoreduplication, and apoptosis by actin depolymerization agent pextenotoxin-2 in human leukemia cells, involving activation of ERK and JNK.
Pectenotoxin-2 (PTX-2) is a natural compound from marine sponges and has been known to inhibit cytokinesis through the depolymerization of actin filaments. To investigate the role of actin dysfunction by PTX-2 in human leukemia cells, we analyzed the effect of PTX-2 on the cell cycle and apoptosis. Cell cycle analysis showed that the depolymerization of actin with PTX-2 induces G2/M phase arrest at 12 h and endoreduplication at 24 h. Analysis of the cell cycle regulatory proteins demonstrated that PTX-2 increases phosphorylation of cdc25c and decreases the protein levels of cdc2 and cyclin B1. The M phase specific marker protein, phospho-histone 3, was also increased by PTX-2. Furthermore, p21 and CDK2, which are associated with the induction of endoreduplication, were also upregulated. PTX-2 also inhibited the growth of leukemia cells and caused a marked increase in apoptosis, as characterized by annexin-V+ cells and caspase-3 activity. Interestingly, we found that induction of G2/M phase arrest, endoreduplication, and apoptosis by PTX-2 is regulated by the extracellular signal-regulated kinase (ERK) and c-jun N-terminal kinase (JNK) pathway. Inhibitors of ERK and JNK more increased the phosphorylation of cdc25c expression at G2/M arrest stages, and decreased p21 and CDK2 expression at endoreduplication stages and Bax expression at apoptotic stages in the presence of PTX-2. These molecular mechanisms provide that PTX-2 induces G2/M phase arrest, endoreduplication, and apoptosis through the ERK and JNK signal pathway via actin depolymerization.
Faculty of Applied Marine Science, Cheju National University, Jeju Special Self-Governing Province 690-756, South Korea.
Dong-Oh
DO
Moon
Mun-Ock
MO
Kim
Sang-Hyuck
SH
Kang
Kyeong-Jun
KJ
Lee
Moon-Soo
MS
Heo
Kwang-Sik
KS
Choi
Yung Hyun
YH
Choi
Gi-Young
GY
Kim
D000199:Actins / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005434:Flow Cytometry; D005663:Furans / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018942:Macrolides; D011714:Pyrans / Q000494:pharmacology*; D000095702:Polyether Toxins
D000199:Actins; D053148:Caspase 3; D048049:Extracellular Signal-Regulated MAP Kinases; D005663:Furans; D048031:JNK Mitogen-Activated Protein Kinases; D018942:Macrolides; D011714:Pyrans; C098380:pectenotoxin 2; D000095702:Polyether Toxins