Expression of hypoxia-inducible carbonic anhydrase-9 relates to angiogenic pathways and independently to poor outcome in non-small cell lung cancer

Cancer Res. 2001 Nov 1;61(21):7992-8.

Abstract

Carbonic anhydrase-9 (CA9), a transmembrane enzyme with an extracellular active site, is involved in the reversible metabolism of the carbon dioxide to carbonic acid. Up-regulation of CA by hypoxia and the hypoxia-inducible factor (HIF) pathway has been recently postulated (Wykoff et al. Cancer Res., 60: 7075-7083, 2000). In the present study we examined the expression of this enzyme in non-small cell lung cancer. Of 107 cases analyzed, 39 (36.4%) had strong membrane/cytoplasmic expression of CA9 and were grouped as positive. The staining was confined around areas of necrosis, and a significant association of CA9 expression with the extent of necrosis was noted (P = 0.004). Nevertheless, 38 of 74 cases with focal or extensive necrosis did not express CA9. CA9 expression was more frequent in the squamous cell histology (P = 0.001) and with advanced T stage (P = 0.009). A significant coexpression of CA9 with platelet-derived endothelial cell growth factor and basic fibroblast growth factor receptor expression was noted. Double staining of CA9 with anti-CD31 monoclonal antibody revealed an overall higher microvessel density in the areas expressing CA9 than in negative areas (P = 0.0005). Thirty-one of 38 CA9-positive cases were positive for HIF1a/HIF2a, but HIF positivity was a more common event (68 of 107) and their patterns of expression were diffuse (not confined in the necrotic areas). A direct association of CA9 expression with epidermal growth factor receptor, c-erbB-2, and MUC1 expression was also noted (P < 0.04). Survival analysis showed that CA9 expression is related to poor prognosis. CA9 expression in tumors with low vascularization defined a prognosis similar to the one of patients with highly angiogenic tumors. Multivariate analysis revealed that CA9 expression is a significant prognostic factor independent of angiogenesis. We conclude that CA9 is an important molecule in non-small cell lung cancer, the up-regulation of which occurs in highly hypoxic/necrotic regions of the tumors. The expression of CA9 is linked to the expression of a constellation of proteins involved in angiogenesis, apoptosis inhibition, and cell-cell adhesion disruption, which explains the strong association of CA9 with poor outcome.

MeSH terms

  • Adenocarcinoma / blood supply
  • Adenocarcinoma / enzymology
  • Adenocarcinoma / pathology
  • Adult
  • Aged
  • Antigens, Neoplasm*
  • Basic Helix-Loop-Helix Transcription Factors
  • Carbonic Anhydrase IX
  • Carbonic Anhydrases*
  • Carcinoma, Non-Small-Cell Lung / blood supply*
  • Carcinoma, Non-Small-Cell Lung / enzymology*
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Carcinoma, Squamous Cell / blood supply
  • Carcinoma, Squamous Cell / enzymology
  • Carcinoma, Squamous Cell / pathology
  • Cell Hypoxia
  • Enzyme Induction
  • ErbB Receptors / biosynthesis
  • Female
  • Fibroblast Growth Factor 2 / biosynthesis
  • Fibroblast Growth Factor 2 / physiology
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Lung Neoplasms / blood supply*
  • Lung Neoplasms / enzymology*
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Mucin-1 / biosynthesis
  • Necrosis
  • Neoplasm Proteins / biosynthesis*
  • Neovascularization, Pathologic / enzymology*
  • Prognosis
  • Receptor, ErbB-2 / biosynthesis
  • Signal Transduction / physiology
  • Thymidine Phosphorylase / biosynthesis
  • Thymidine Phosphorylase / physiology
  • Trans-Activators / biosynthesis
  • Transcription Factors / biosynthesis

Substances

  • Antigens, Neoplasm
  • Basic Helix-Loop-Helix Transcription Factors
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Mucin-1
  • Neoplasm Proteins
  • Trans-Activators
  • Transcription Factors
  • Fibroblast Growth Factor 2
  • endothelial PAS domain-containing protein 1
  • Thymidine Phosphorylase
  • ErbB Receptors
  • Receptor, ErbB-2
  • CA9 protein, human
  • Carbonic Anhydrase IX
  • Carbonic Anhydrases