p28GANK inhibits endoplasmic reticulum stress-induced cell death via enhancement of the endoplasmic reticulum adaptive capacity.
It has been shown that oncoprotein p28(GANK), which is consistently overexpressed in human hepatocellular carcinoma (HCC), plays a critical role in tumorigenesis of HCC. However, the underlying mechanism remains unclear. Here, we demonstrated that p28(GANK) inhibits apoptosis in HCC cells induced by the endoplasmic reticulum (ER) stress. During ER stress, p28(GANK) enhances the unfolded protein response, promotes ER recovery from translational repression, and thereby facilitates cell's ability to cope with the stress conditions. Furthermore, p28(GANK) upregulates glucose-regulated protein 78 (GRP78), a key ER chaperone protein, which subsequently enhances the ER folding capacity and promotes recovery from ER stress. We also demonstrated that p28(GANK) increases p38 mitogen-activated protein kinase and Akt phosphorylation, and inhibits nuclear factor kappa B (NF-kappaB) activation under ER stress, which in turn contributes to GRP78 upregulation. Taken together, our results indicate that p28(GANK) inhibits ER stress-induced apoptosis in HCC cells, at least in part, by enhancing the adaptive response and GRP78 expression. We propose that p28(GANK) has potential implications for HCC progression under the ER stress conditions.
Dai
Rong-Yang
RY
State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute and Cancer Institute of Shanghai Jiao Tong University, Shanghai 200032, China.
Chen
Yao
Y
Fu
Jing
J
Dong
Li-Wei
LW
Ren
Yi-Bin
YB
Yang
Guang-Zhen
GZ
Qian
You-Wen
YW
Cao
Jie
J
Tang
Shan-Hua
SH
Yang
Sheng-Li
SL
Wang
Hong-Yang
HY
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D015536:Down-Regulation; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000473:pathology; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D041681:NIH 3T3 Cells; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000235:genetics; D013312:Stress, Physiological; D056811:Unfolded Protein Response / Q000502:physiology*; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D016328:NF-kappa B; C403591:PSMD10 protein, human; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D051057:Proto-Oncogene Proteins c-akt; D048051:p38 Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex