Endoplasmic reticulum stress-mediated signaling pathway of gastric cancer apoptosis.
OBJECTIVE
To investigate ER stress-mediated CHOP-signaling pathway of gastric cancer apoptosis in vitro and in vivo.


METHODS
Based on the dose-and time-response experiments about tunicamycin (TM),gastric cancer cell line BGC823 was treated with 10tg/mL of TM for 24h. BGC823 apoptosis was detected with TUNEL assay and ultrastructural changes in BGC823 cells under ER stress were observed with transmission electron microscopy (TEM). RT-PCR and western blot-ting were used to determine the expression of ERS-related proteins, glucose-regulated protein 78 (GRP78) and CHOP and apoptosis-associated protein B-cell lympho-ma 2 (Bcl-2). After the knockdown of CHOP, the changes were also observed in vitro and in vivo.


RESULTS
TEM assay showed that after treatment with TM, BGC823 cell size became smaller with ER dilation, vacuolization and karyopyknosis. RT-PCR and western blotting indicated that TM up-regulated GRP78 and CHOP expression and down-regulated Bcl-2 expression. The knock-down of CHOP could convert Bcl-2 expression and reduce BGC823 apoptosis caused by ERS in vitro and in vivo, but failed to influence GRP78.


CONCLUSIONS
TM can induce ESR and regulate downstream molecules CHOP up-regulation and Bcl-2 down-regulation which lead to BGC823 apoptosis. This study may provide a new theoretical basis for the pathogenesis of gastric cancer.
Department of Histology and Embryology, Medical School of Zhengzhou University, Zhengzhou, Henan, China.
Yu-Ying
YY
Xu
Yan-Wen
YW
You
Xiu-Hua
XH
Ren
Yi
Y
Ding
Jing
J
Cao
Wei-Dong
WD
Zang
Ruo
R
Feng
Qin-Xian
QX
Zhang
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D046529:Microscopy, Electron, Transmission; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D047368:Tumor Burden; D014415:Tunicamycin / Q000494:pharmacology
C497249:DDIT3 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D014415:Tunicamycin; D051742:Transcription Factor CHOP