The redox protein thioredoxin-1 (Trx-1) increases hypoxia-inducible factor 1alpha protein expression: Trx-1 overexpression results in increased vascular endothelial growth factor production and enhanced tumor angiogenesis.
Hypoxia-inducible factor 1 (HIF-1), a heterodimer of HIF-1alpha and HIF-1beta subunits, is a transcriptional activator central to the cellular response to low oxygen that includes metabolic adaptation, angiogenesis, metastasis, and inhibited apoptosis. Thioredoxin-1 (Trx-1) is a small redox protein overexpressed in a number of human primary tumors. We have examined the effects of Trx-1 on HIF activity and the activation of downstream genes. Stable transfection of human breast carcinoma MCF-7 cells with human Trx-1 caused a significant increase in HIF-1alpha protein levels under both normoxic (20% oxygen) and hypoxic (1% oxygen) conditions. Trx-1 increased hypoxia-induced HIF-1 transactivation activity measured using a luciferase reporter under the control of the hypoxia response element. Changes in HIF-1alpha mRNA levels did not account for the changes observed at the protein level, and HIF-1beta protein levels did not change. Trx-1 transfection also caused a significant increase in the protein products of hypoxia-responsive genes, including vascular endothelial growth factor (VEGF) and nitric oxide synthase 2 in a number of different cell lines (MCF-7 human breast and HT29 human colon carcinomas and WEHI7.2 mouse lymphoma cells) under both normoxic and hypoxic conditions. The pattern of expression of the different isoforms of VEGF was not changed by Trx-1. Transfection of a redox-inactive Trx-1 (C32S/C35S) markedly decreased levels of HIF-1alpha protein, HIF-1 transactivating activity, and VEGF protein in MCF-7 cells compared with empty vector controls. In vivo studies using WEHI7.2 cells transfected with Trx-1 showed significantly increased tumor VEGF and angiogenesis. The results suggest that Trx-1 increases HIF-1alpha protein levels in cancer cells and increases VEGF production and tumor angiogenesis.
Arizona Cancer Center, University of Arizona, Tucson, Arizona, 85724-5024, USA. swelsh@azcc.arizona.edu
Sarah J
SJ
Welsh
William T
WT
Bellamy
Margaret M
MM
Briehl
Garth
G
Powis
D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001943:Breast Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology; D003110:Colonic Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors / Q000096:biosynthesis* / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines / Q000096:biosynthesis* / Q000235:genetics; D008223:Lymphoma / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D018336:Receptors, Aryl Hydrocarbon; D013879:Thioredoxins / Q000096:biosynthesis / Q000494:pharmacology; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
C497396:ARNT protein, human; C497397:Arnt protein, mouse; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines; D008565:Membrane Proteins; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; C491203:TXN protein, human; D014157:Transcription Factors; C491200:Txndc2 protein, mouse; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D013879:Thioredoxins; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse