Moscatilin induces apoptosis in human colorectal cancer cells: a crucial role of c-Jun NH2-terminal protein kinase activation caused by tubulin depolymerization and DNA damage.
OBJECTIVE
To study the effect of moscatilin (purified from the stem of orchid Dendrobrium loddigesii) on the proliferation of human colorectal cancer HCT-116 cells in vitro and in vivo.


METHODS
The growth inhibition of moscatilin was screened on several human cancer cell lines. The effect of moscatilin on tubulin was detected in vitro. Following moscatilin treatment on HCT-116 cells, c-Jun NH(2)-terminal protein kinase (JNK) and caspase activation was studied by Western blot analysis, and DNA damage was done by Comet assay. Specific JNK inhibitor SP600125 was cotreated to reverse moscatilin-induced apoptosis. Tumor growth inhibition of moscatilin was done on HCT-116 xenograft models.


RESULTS
Moscatilin induced a time-dependent arrest of the cell cycle at G(2)-M, with an increase of cells at sub-G(1). Moscatilin inhibited tubulin polymerization, suggesting that it might bind to tubulins. Moscatilin also induced the phosphorylation of JNK1/2. SP600125 significantly inhibited the activation of caspase-9 and caspase-3 and the subsequent moscatilin-induced apoptosis. The data suggest that JNK activation may contribute to moscatilin-mediated apoptosis signaling. A parallel experiment showed that SP600125 significantly inhibits Taxol- and vincristine-induced HCT-116 cell apoptosis. This suggests that the JNK activation may be a common mechanism for tubulin-binding agents. Moreover, moscatilin induces DNA damage, phosphorylation of H2AX and p53, and up-regulation of p21. Our HCT-116 xenograft models show the in vivo efficacy of moscatilin.


CONCLUSIONS
In summary, our results suggest that moscatilin induces apoptosis of colorectal HCT-116 cells via tubulin depolymerization and DNA damage stress and that this leads to the activation of JNK and mitochondria-involved intrinsic apoptosis pathway.
Chen
Tzu-Hsuan
TH
Pharmacological Institute and School of Pharmacy, College of Medicine, National Taiwan University, Taiwan, Republic of China.
Pan
Shiow-Lin
SL
Guh
Jih-Hwa
JH
Liao
Cho-Hwa
CH
Huang
Der-Yi
DY
Chen
Chien-Chih
CC
Teng
Che-Ming
CM
D000818:Animals; D017209:Apoptosis; D001593:Benzyl Compounds / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002469:Cell Separation; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D051379:Mice; D009368:Neoplasm Transplantation; D014404:Tubulin / Q000737:chemistry*
D001593:Benzyl Compounds; D014404:Tubulin; C071845:dendrophenol; D048031:JNK Mitogen-Activated Protein Kinases