title: Hypoxia-increased RAGE and P2X7R expression regulates tumor cell invasion through phosphorylation of Erk1/2 and Akt and nuclear translocation of NF-{kappa}B.
abstract: The role of hypoxia in regulating tumor progression is still controversial. Here, we demonstrate that, similarly to what previously observed by us in human prostate and breast tumor samples, hypoxia increases expression of the receptor for advanced glycation end products (RAGE) and the purinergic receptor P2X7 (P2X7R). The role of hypoxia was shown by the fact that hypoxia-inducible factor (HIF)-1α silencing downregulated RAGE and P2X7R protein levels as well as nuclear factor-kappaB (NF-κB) expression. In contrast, NF-κB silencing reduced P2X7R expression without affecting RAGE protein levels or nuclear accumulation of HIF-1α. Treatment of hypoxic tumor cells with HMGB1 and BzATP ligands, respectively, of RAGE and P2X7R, activated a signaling pathway that, through Akt and Erk phosphorylation, determines nuclear accumulation of NF-κB and increases cell invasion. Inhibition of Akt by SH5 and Erk by INH1 prevented both nuclear translocation of NF-κB and cell invasion. Moreover, silencing RAGE and P2X7R abolished nuclear accumulation of NF-κB as well as cell invasion without affecting HIF-1α stabilization. Once in the nucleus, NF-κB would contribute to cell survival and invasion under hypoxia, by maintaining RAGE and P2X7R expression levels and matrix metalloproteinases 2 and 9 synthesis. These results show that, hypoxia can upregulate expression levels of membrane receptors that, by binding extracellular molecules eventually released by necrotic cells, contribute to the increased invasiveness of transformed tumor cells. Moreover, these observations strengthen our working hypothesis that upregulation of damage-associated molecular patterns receptors by HIF-1α represents the crucial event bridging hypoxia and inflammation in obtaining the malignant phenotype.
authors.affiliation: Department of Experimental Medicine, Sapienza University, Rome, Italy. marcotafani@yahoo.com
authors.forename: Marco
authors.initials: M
authors.lastname: Tafani
authors.forename: Luana
authors.initials: L
authors.lastname: Schito
authors.forename: Laura
authors.initials: L
authors.lastname: Pellegrini
authors.forename: Lidia
authors.initials: L
authors.lastname: Villanova
authors.forename: Gabriella
authors.initials: G
authors.lastname: Marfe
authors.forename: Tahira
authors.initials: T
authors.lastname: Anwar
authors.forename: Roberta
authors.initials: R
authors.lastname: Rosa
authors.forename: Manuela
authors.initials: M
authors.lastname: Indelicato
authors.forename: Massimo
authors.initials: M
authors.lastname: Fini
authors.forename: Bruna
authors.initials: B
authors.lastname: Pucci
authors.forename: Matteo A
authors.initials: MA
authors.lastname: Russo
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism*; D005260:Female; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016328:NF-kappa B; D034741:RNA, Small Interfering; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D058486:Receptors, Purinergic P2X7; D051057:Proto-Oncogene Proteins c-akt; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9