Cancer and Metastasis Reviews

, Volume 26, Issue 2, pp 299–310

Regulation of tumor pH and the role of carbonic anhydrase 9

  • Pawel Swietach
  • Richard D. Vaughan-Jones
  • Adrian L. Harris
Article

DOI: 10.1007/s10555-007-9064-0

Cite this article as:
Swietach, P., Vaughan-Jones, R.D. & Harris, A.L. Cancer Metastasis Rev (2007) 26: 299. doi:10.1007/s10555-007-9064-0

Abstract

The high metabolic rate required for tumor growth often leads to hypoxia in poorly-perfused regions. Hypoxia activates a complex gene expression program, mediated by hypoxia inducible factor 1 (HIF1α). One of the consequences of HIF1α activation is up-regulation of glycolysis and hence the production of lactic acid. In addition to the lactic acid-output, intracellular titration of acid with bicarbonate and the engagement of the pentose phosphate shunt release CO2 from cells. Expression of the enzyme carbonic anhydrase 9 on the tumor cell surface catalyses the extracellular trapping of acid by hydrating cell-generated CO2 into \({\text{HCO}}^{ - }_{3} \) and H+. These mechanisms contribute towards an acidic extracellular milieu favoring tumor growth, invasion and development. The lactic acid released by tumor cells is further metabolized by the tumor stroma. Low extracellular pH may adversely affect the intracellular milieu, possibly triggering apoptosis. Therefore, primary and secondary active transporters operate in the tumor cell membrane to protect the cytosol from acidosis. We review mechanisms regulating tumor intracellular and extracellular pH, with a focus on carbonic anhydrase 9. We also review recent evidence that may suggest a role for CA9 in coordinating pHi among cells of large, unvascularized cell-clusters.

Keywords

Fluorescence Hypoxia Imaging Intracellular and extracellular pH Nuclear magnetic resonance 

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Pawel Swietach
    • 1
  • Richard D. Vaughan-Jones
    • 1
  • Adrian L. Harris
    • 2
  1. 1.Department of Physiology, Anatomy and GeneticsBurdon Sanderson Cardiac Science CentreOxfordUK
  2. 2.Weatherall Institute of Molecular MedicineJohn Radcliffe HospitalOxfordUK