title: Green tea extract and (-)-epigallocatechin-3-gallate inhibit hypoxia- and serum-induced HIF-1alpha protein accumulation and VEGF expression in human cervical carcinoma and hepatoma cells.
abstract: Green tea extract and its major component (-)-epigallocatechin-3-gallate (EGCG) exhibit antiangiogenic activities in various experimental tumor models. A growing body of evidence has established that hypoxia-inducible factor-1alpha (HIF-1alpha) and its downstream target, vascular endothelial growth factor (VEGF), play a critical role in tumor angiogenesis. In this study, we investigated the effect of green tea extract and EGCG on HIF-1alpha and VEGF expression in human cervical carcinoma (HeLa) and hepatoma (HepG2) cells. Our results showed that green tea extract and EGCG significantly inhibited hypoxia- and serum-induced HIF-1alpha protein accumulation in these cancer cells but had no effects on HIF-1alpha mRNA expression. Suppression of HIF-1alpha protein by green tea extract and EGCG also resulted in a drastic decrease in VEGF expression at both mRNA and protein levels. The mechanisms of green tea extract and EGCG inhibition of hypoxia-induced HIF-1alpha protein accumulation seem to involve the blocking of both phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2 signaling pathways and the enhancing of HIF-1alpha protein degradation through the proteasome system. In addition, green tea extract and EGCG inhibited serum-induced HIF-1alpha protein and VEGF expression by interfering with the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin signaling pathways, which play a crucial role in the protein translational machinery cascade. Functionally, green tea extract and EGCG abolished both chemoattractant- and hypoxia-stimulated HeLa cell migration. Our data suggested that HIF-1alpha/VEGF function as therapeutic target for green tea extract and EGCG in the context of cancer chemoprevention and anticancer therapy.
authors.affiliation: Division of Surgical, Therapeutic and Bioengineering Sciences, Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Health Sciences Campus, 2250 Alcazar Street, CSA103, Los Angeles, CA 90033, USA.
authors.forename: Qunzhou
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xudong
authors.initials: X
authors.lastname: Tang
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Lu
authors.forename: Zuofeng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jianyu
authors.initials: J
authors.lastname: Rao
authors.forename: Anh D
authors.initials: AD
authors.lastname: Le
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D015687:Cell Hypoxia; D003470:Culture Media; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020123:Sirolimus / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D016588:Anticarcinogenic Agents; D003470:Culture Media; D051793:Hypoxia-Inducible Factor 1; D010936:Plant Extracts; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D002392:Catechin; C045651:epigallocatechin gallate; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020123:Sirolimus