title: Epstein-Barr virus latent membrane protein 1 induces synthesis of hypoxia-inducible factor 1 alpha.
abstract: Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric basic helix-loop-helix transcription factor composed of HIF-1 alpha and HIF-1 beta that is the central regulator of responses to hypoxia. The specific binding of HIF-1 to the hypoxia-responsive element (HRE) induces the transcription of genes that respond to hypoxic conditions, including vascular endothelial growth factor (VEGF). Here we report that expression of HIF-1 alpha is increased in diverse Epstein-Barr virus (EBV)-infected type II and III cell lines, which express EBV latent membrane protein 1 (LMP1), the principal EBV oncoprotein, as well as other latency proteins, but not in the parental EBV-negative cell lines. We show first that transfection of an LMP1 expression plasmid into Ad-AH cells, an EBV-negative nasopharyngeal epithelial cell line, induces synthesis of HIF-1 alpha protein without increasing its stability or mRNA level. The mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059 markedly reduces induction of HIF-1 alpha by LMP1. Catalase, an H(2)O(2) scavenger, strongly suppresses LMP1-induced production of H(2)O(2), which results in a decrease in the expression of HIF-1 alpha induced by LMP1. Inhibition of the NF-kappa B, c-jun N-terminal kinase, p38 MAPK, and phosphatidylinositol 3-kinase pathways did not affect HIF-1 alpha expression. Moreover, LMP1 induces HIF-1 DNA binding activity and upregulates HRE and VEGF promoter transcriptional activity. Finally, LMP1 increases the appearance of VEGF protein in extracellular fluids; induction of VEGF is suppressed by PD98059 or catalase. These results suggest that LMP1 increases HIF-1 activity through induction of HIF-1 alpha protein expression, which is controlled by p42/p44 MAPK activity and H(2)O(2). The ability of EBV, and specifically its major oncoprotein, LMP1, to induce HIF-1 alpha along with other invasiveness and angiogenic factors reported previously discloses additional oncogenic properties of this tumor virus.
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7295, USA.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Wakisaka
authors.forename: Satoru
authors.initials: S
authors.lastname: Kondo
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yoshizaki
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Murono
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Furukawa
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Pagano
mesh_terms: D000818:Animals; D002460:Cell Line; D020031:Epstein-Barr Virus Infections / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D006367:HeLa Cells; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020935:MAP Kinase Signaling System; D051379:Mice; D008819:Mice, Nude; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection; D014763:Viral Matrix Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: C037662:EBV-associated membrane antigen, Epstein-Barr virus; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016328:NF-kappa B; D012333:RNA, Messenger; D014157:Transcription Factors; D014763:Viral Matrix Proteins; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases