Mechanism of cancer cell adaptation to metabolic stress: proteomics identification of a novel thyroid hormone-mediated gastric carcinogenic signaling pathway.
Gastric cancer is the second most common cancer worldwide and has a poor prognosis. To determine the mechanism of adaptation to metabolic stress in cancer cells, we used gastric cancer as a model system to reveal the potential signaling pathways involved. Two-dimensional polyacrylamide gel electrophoresis coupled with ESI-Q-TOF MS/MS analysis was used to identify differentially expressed proteins between gastric tumor tissues and the corresponding noncancerous tissues. In total, 107 spots with significant alteration (+/-over 2-fold, p < 0.05) were positively identified by MS/MS analysis. Altered expression of representative proteins was validated by RT-PCR and Western blotting. Cluster analysis of the changed proteins revealed an interesting group of metabolic proteins, which suggested accumulation of triiodothyronine (T(3); the major functional component of thyroid hormone) and overexpression of hypoxia-induced factor (HIF) in gastric carcinoma. These observations were further confirmed by electrochemiluminescence immunoassay and immunohistochemistry. T(3)-induced expression of HIF1-alpha and vascular endothelial growth factor was further verified using a gastric cancer cell line and in vivo mouse model. Because the early accumulation of HIF1-alpha was found to be independent of de novo transcription, we also found that the cytosolic cascade phosphatidylinositol 3-kinase/Akt pathway sensitive to T(3) stimulus was involved. Furthermore we demonstrated that T(3)-induced overexpression of HIF1-alpha was mediated by fumarate accumulation and could be enhanced by fumarate hydratase inactivation but inhibited by 2-oxoglutarate. These results provide evidence for alteration of metabolic proteins and dysfunction of thyroid hormone regulation in gastric tumors, and a novel thyroid hormone-mediated tumorigenic signaling pathway is proposed. Our findings are considered a significant step toward a better understanding of adaptations to metabolic stress in gastric carcinogenesis.
Liu
Rui
R
The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
Li
Zhenjun
Z
Bai
Shujun
S
Zhang
Haiyuan
H
Tang
Minghai
M
Lei
Yunlong
Y
Chen
Lijuan
L
Liang
Shufang
S
Zhao
Ying-Lan
YL
Wei
Yuquan
Y
Huang
Canhua
C
D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D045744:Cell Line, Tumor; D002951:Citrates / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D005649:Fumarate Hydratase / Q000378:metabolism; D005650:Fumarates / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D040901:Proteomics; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015203:Reproducibility of Results; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects; D013963:Thyroid Hormones / Q000378:metabolism*; D014284:Triiodothyronine / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D002951:Citrates; D005650:Fumarates; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D013963:Thyroid Hormones; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D014284:Triiodothyronine; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D005649:Fumarate Hydratase