c-Jun N-terminal kinase is required for vitamin E succinate-induced apoptosis in human gastric cancer cells.
OBJECTIVE
To investigate the roles of c-Jun N-terminal kinase (JNK) signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells.


METHODS
Human gastric cancer cell lines (SGC-7901) were treated with vitamin E succinate (VES) at 5, 10, 20 mg/L. Succinic acid and vitamin E were used as vehicle controls and condition medium only as an untreated (UT) control. Apoptosis was observed by 4', 6-diamidine-2'-phenylindole dihydrochloride (DAPI) staining for morphological changes and by DNA fragmentation for biochemical alterations. Western blot analysis was applied to measure the expression of JNK and phosphorylated JNK. After the cells were transiently transfected with dominant negative mutant of JNK (DN-JNK) followed by treatment of VES, the expression of JNK and c-Jun protein was determined.


RESULTS
The apoptotic changes were observed after VES treatment by DNA fragmentation. DNA ladder in the 20 mg/L VES group was more clearly seen than that in 10 mg/L VES group and was not detected following treatment of UT control, succinate and vitamin E. VES at 5, 10 and 20 mg/L increased the expression of p-JNK by 2.5-, 2.8- and 4.2-fold, respectively. VES induced the phosphorylation of JNK beginning at 1.5 h and produced a sustained increase for 24 h with the peak level at 12 h. Transient transfection of DN-JNK blocked VES-triggered apoptosis by 52%. DN-JNK significantly increased the level of JNK, while decreasing the expression of VES-induced c-Jun protein.


CONCLUSIONS
VES-induced apoptosis in human gastric cancer SGC-7901 cells involves JNK signaling pathway via c-Jun and its downstream transcription factor.
Wu
Kun
K
Department of Nutrition and Food Hygiene, Public Health School, Harbin Medical University, Harbin 150001, Heilongjiang Province, China. wukun@public.hr.hl.cn
Zhao
Yan
Y
Li
Gui-Chang
GC
Yu
Wei-Ping
WP
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D045744:Cell Line, Tumor / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D013274:Stomach Neoplasms; D024505:Tocopherols; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000494:pharmacology*
D014810:Vitamin E; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D024505:Tocopherols