Protein tyrosine kinase, JNK, and ERK involvement in pseudolaric acid B-induced apoptosis of human breast cancer MCF-7 cells.
OBJECTIVE
To investigate the apoptotic mechanism of pseudolaric acid B (PAB) in human breast cancer MCF-7 cells.


METHODS
3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide analysis and morphological changes were applied to detect apoptosis. The percentage of apoptotic and necrotic cells were calculated by the lactate dehydrogenase activity-based cytotoxicity assay, and the protein expression was examined by Western blot analysis.


RESULTS
PAB and/or the mitogen-activated protein kinases, including p38, c-Jun-N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), did not participate in necrosis. P38 had no obvious function on apoptosis after 4 micromol/L PAB treatment for 36 h, but PAB induced JNK phosphorylation and inhibited ERK phosphorylation in the apoptotic process. In this study the inhibitor of protein tyrosine kinase (PTK) genistein inverted the inhibitory effect of PAB, instead promoting the survival of MCF-7 cells. Like genistein, another PTK inhibitor AG1024 had a similar effect on PAB-treated MCF-7 cells, indicating that PAB activated PTK to induce apoptosis. Together with PAB, genistein increased the expression of p-ERK, and decreased the expressions of JNK and p-JNK in PAB-treated MCF-7 cells at 36 h. And it is considered that the p-ERK and p-JNK were active patterns of ERK and JNK, respectively.


CONCLUSIONS
PTK were upstream of ERK and JNK, and PTK induced apoptosis through activating JNK and inactivating ERK in PAB-treated MCF-7 cells.
Yu
Jing-hua
JH
China-Japan Research Institute of Medical Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China.
Wang
Hong-jun
HJ
Li
Xiang-ru
XR
Tashiro
Shin-ichi
S
Onodera
Satoshi
S
Ikejima
Takashi
T
D016588:Anticarcinogenic Agents / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004224:Diterpenes / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005260:Female; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009363:Neoplasm Proteins / Q000096:biosynthesis; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*
D016588:Anticarcinogenic Agents; D000972:Antineoplastic Agents, Phytogenic; D004224:Diterpenes; D009363:Neoplasm Proteins; C058391:pseudolaric acid B; D019833:Genistein; D007770:L-Lactate Dehydrogenase; D011505:Protein-Tyrosine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases