The transcriptional complex hypoxia-inducible factor-1 (HIF-1) has emerged as an important mediator of gene expression patterns in tumors, although the range of responding genes is still incompletely defined. Here we show that the tumor-associated carbonic anhydrases (CAs) are tightly regulated by this system. Both CA9 and CA12 were strongly induced by hypoxia in a range of tumor cell lines. In renal carcinoma cells that are defective for the von Hippel-Lindau (VHL) tumor suppressor, up-regulation of these CAs is associated with loss of regulation by hypoxia, consistent with the critical function of pVHL in the regulation of HIF-1. Further studies of CA9 defined a HIF-1-dependent hypoxia response element in the minimal promoter and demonstrated that tight regulation by the HIF/pVHL system was reflected in the pattern of CA IX expression within tumors. Generalized up-regulation of CA IX in VHL-associated renal cell carcinoma contrasted with focal perinecrotic expression in a variety of non-VHL-associated tumors. In comparison with vascular endothelial growth factor mRNA, expression of CA IX demonstrated a similar, although more tightly circumscribed, pattern of expression around regions of necrosis and showed substantial although incomplete overlap with activation of the hypoxia marker pimonidazole. These studies define a new class of HIF-1-responsive gene, the activation of which has implications for the understanding of hypoxic tumor metabolism and which may provide endogenous markers for tumor hypoxia.

Type

Journal article

Journal

Cancer Res

Publication Date

15/12/2000

Volume

60

Pages

7075 - 7083

Keywords

Blotting, Western, Carbonic Anhydrases, Carcinoma, Carcinoma, Renal Cell, DNA-Binding Proteins, Endothelial Growth Factors, Genes, Reporter, Humans, Hypoxia, Hypoxia-Inducible Factor 1, Hypoxia-Inducible Factor 1, alpha Subunit, Immunoblotting, Immunohistochemistry, In Situ Hybridization, Kidney Neoplasms, Lymphokines, Models, Genetic, Necrosis, Nitroimidazoles, Nuclear Proteins, Oxygen, Plasmids, Promoter Regions, Genetic, RNA, RNA, Messenger, Radiation-Sensitizing Agents, Skin Neoplasms, Transcription Factors, Tumor Cells, Cultured, Up-Regulation, Urinary Bladder Neoplasms, Vascular Endothelial Growth Factor A, Vascular Endothelial Growth Factors