A Key role for cyclic AMP-responsive element binding protein in hypoxia-mediated activation of the angiogenesis factor CCN1 (CYR61) in Tumor cells.
Hypoxia is a prominent feature of solid tumors known to contribute to malignant progression and therapeutic resistance. Cancer cells adapt to hypoxia using various pathways, allowing tumors to thrive in a low oxygen state. Induction of new blood vessel formation via the secretion of proangiogenic factors is one of the main adaptive responses engaged by tumor cells under hypoxic conditions. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that plays a pivotal role in mediating such responses. In addition, several other transcription factors have also been implicated in hypoxic gene regulation, either independently or in cooperation with HIF-1. In this work, we show that the expression of the angiogenesis-related, immediate early gene CCN1 (formerly known as CYR61), considered to be involved in tumor growth and invasiveness, is enhanced upon hypoxia stress primarily in a protein kinase A and cyclic AMP-responsive element binding protein (CREB) and CRE-dependent manner in various cell lines. The hypoxia-mediated activation of the CCN1 promoter is independent of HIF-1 and HIF-2, as shown by small interfering RNA knockdown. We identify the cis element in the mouse CCN1 promoter responsible for CREB binding to be one of two partial CRE sites present in the promoter. Moreover, we report for the first time that CREB-mediated CCN1 transcription is enhanced in hypoxic regions of tumors in vivo. Identifying and characterizing the molecular mechanisms that govern the response of tumors to hypoxia may be instrumental to identify the tumors that will respond favorably to inhibition of angiogenesis and thus lead to the development of treatments that could complement hypoxia-inducing treatment modalities.
Meyuhas
Ronit
R
Department of Virology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Pikarsky
Eli
E
Tavor
Einat
E
Klar
Avihu
A
Abramovitch
Rinat
R
Hochman
Jacob
J
Lago
Tal Goshen
TG
Honigman
Alik
A
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015687:Cell Hypoxia; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D055515:Cysteine-Rich Protein 61; D015232:Dinoprostone / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D017874:Immediate-Early Proteins / Q000235:genetics*; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008156:Luciferases / Q000378:metabolism; D016399:Lymphoma, T-Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic; D015347:RNA Probes; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014158:Transcription, Genetic; D014162:Transfection; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D000242:Cyclic AMP; D017362:Cyclic AMP Response Element-Binding Protein; D017868:Cyclic AMP-Dependent Protein Kinases; D055515:Cysteine-Rich Protein 61; D015232:Dinoprostone; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008156:Luciferases; D015347:RNA Probes; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000099162:Endothelial PAS Domain-Containing Protein 1; C501848:CCN1 protein, human; C491850:CCN1 protein, mouse; C492004:Creb1 protein, mouse; C497442:HIF1A protein, human; C497443:Hif1a protein, mouse