Thymoquinone inhibits proliferation in gastric cancer via the STAT3 pathway in vivo and in vitro.
OBJECTIVE
To elucidate the mechanism of thymoquinone (TQ)-induced apoptosis in human gastric cancer cells in vitro and in vivo.


METHODS
HGC27, BGC823, and SGC7901 cells were cultured in vitro and treated with TQ (0, 10, 25, 50, 75, 100, 125 μmol/L) for 12 h, 24 h, and 36 h, and then the proliferation inhibitory rates were detected by methylthiazole tetrazolium assay. Apoptosis was observed after Hoechst staining. The protein expressions of signal transducer and activator of transcription (STAT)3, p-STAT3, STAT5, p-STAT5, phospho-janus-activated kinase 2 (JAK2), JAK2, p-Src, Src, glyceraldehyde-3-phosphate dehydrogenase, lamin-A, survivin, Cyclin D, Bcl-2, Bax, peroxisome proliferator activated receptor, and caspase-3,7,9 were detected by western blot. Cell cycle and apoptosis were determined with flow cytometry. TQ induced dose-dependent apoptotic cell death in HGC27 cells was measured by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) analysis and Hoechst 33258.


RESULTS
TQ inhibited the phosphorylation of STAT3 but not STAT5. TQ-induced downregulation of STAT3 activation was associated with a reduction in JAK2 and c-Src activity. TQ also downregulated the expression of STAT3-regulated genes, such as Bcl-2, cyclin D, survivin, and vascular endothelial growth factor, and activated caspase-3,7,9. Consistent with the in vitro results, TQ was significantly effective as an antitumor agent in a xenograft tumor mouse model.


CONCLUSIONS
This study provides strong evidence that downregulation of the STAT3 signaling pathway mediates TQ-induced apoptosis in gastric cancer.
Wen-Qian Zhu, Jun Wang, Xu-Feng Guo, Zhou Liu, Wei-Guo Dong, Department of Gastroenterology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Disease, Wuhan 430060, Hubei Province, China.
Wen-Qian
WQ
Zhu
Wen-Qian Zhu, Jun Wang, Xu-Feng Guo, Zhou Liu, Wei-Guo Dong, Department of Gastroenterology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Disease, Wuhan 430060, Hubei Province, China.
Jun
J
Wang
Wen-Qian Zhu, Jun Wang, Xu-Feng Guo, Zhou Liu, Wei-Guo Dong, Department of Gastroenterology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Disease, Wuhan 430060, Hubei Province, China.
Xu-Feng
XF
Guo
Wen-Qian Zhu, Jun Wang, Xu-Feng Guo, Zhou Liu, Wei-Guo Dong, Department of Gastroenterology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Disease, Wuhan 430060, Hubei Province, China.
Zhou
Z
Liu
Wen-Qian Zhu, Jun Wang, Xu-Feng Guo, Zhou Liu, Wei-Guo Dong, Department of Gastroenterology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Disease, Wuhan 430060, Hubei Province, China.
Wei-Guo
WG
Dong
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D016227:Benzoquinones / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D053614:Janus Kinase 2 / Q000378:metabolism; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010766:Phosphorylation; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D013997:Time Factors; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays; D019061:src-Family Kinases / Q000378:metabolism
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D016227:Benzoquinones; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D019061:src-Family Kinases; C003466:thymoquinone
Apoptosis; Gastric cancer; Proliferation; STAT3; Thymoquinone