GRP78 is implicated in the modulation of tumor aerobic glycolysis by promoting autophagic degradation of IKKβ.
Compared with normal differentiated cells, cancer cells take up much more glucose and metabolize it mainly via aerobic glycolysis. This metabolic phenotype is characterized with high expression of glucose transporters (Gluts) and pyruvate kinase M2 (PKM2). Glucose regulated protein 78 (GRP78) is a glucose-sensing protein and frequently up-regulated in cancer cells, however, whether it is directly implicated in glucose metabolism remains to be elucidated. Here we report that upon glucose deficiency, the induction of GRP78 resulted in enhanced HIF-1α transcription, accompanied by a transient increased expression of Glut-1. In addition, GRP78 was likely to facilitate the membrane translocation of Glut-1 via protein-protein interaction. Glucose starvation-stimulated GRP78 also impaired the expression of PKM2 but promoted the expression of mitochondrial pyruvate dehydrogenase A (PDHA) and B (PDHB), resulting in the metabolic shift from glycolysis to the TCA cycle. Interestingly, the inhibition of PKM2 by GRP78 was abrogated when glucose supply was restored, suggesting that GRP78 and PKM2 expressions are adaptable to the nutritional levels in the microenvironment. Further mechanistic study indicated that GRP78 overexpression activated the Class III PI3K-mediated autophagy pathway and induced autophagic degradation of IKKβ, which caused inactivation of NF-κB pathway and subsequently altered the expression of PKM2 and HIF-1α. Our study establishes GRP78 and PKM2 as the crucial molecular links between cancer cell glucose metabolism and tumor microenvironment alterations.
Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan 030006, China.
Zongwei
Z
Li
Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan 030006, China.
Yingying
Y
Wang
College of Life Sciences, University of Dundee, Dundee, DD1 5EH Scotland, UK.
Ian P
IP
Newton
Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan 030006, China.
Lichao
L
Zhang
Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan 030006, China.
Pengyu
P
Ji
Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan 030006, China; College of Life Science, Zhejiang Chinese Medical University, Hangzhou 310053, China. Electronic address: lzy@sxu.edu.cn.
Zhuoyu
Z
Li
D001343:Autophagy; D002352:Carrier Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D000091342:Endoplasmic Reticulum Chaperone BiP; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000235:genetics / Q000378:metabolism; D006019:Glycolysis; D057809:HEK293 Cells; D019073:HT29 Cells; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D051550:I-kappa B Kinase / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D013963:Thyroid Hormones / Q000378:metabolism; D000097810:Thyroid Hormone-Binding Proteins
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D005947:Glucose; D051272:Glucose Transporter Type 1; D006360:Heat-Shock Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051550:I-kappa B Kinase; D019344:Lactic Acid; D008565:Membrane Proteins; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D034741:RNA, Small Interfering; D013963:Thyroid Hormones; D000097810:Thyroid Hormone-Binding Proteins; C000717247:HSPA5 protein, human
Autophagy; Class III PI3K; GRP78; Glycolysis; NF-κB; PKM2