Carbonic anhydrase 9

Function

Carbonic anhydrases (CAs) are a large family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide. They participate in a variety of biological processes, including respiration, calcification, acid-base balance, bone resorption, and the formation of aqueous humor, cerebrospinal fluid, saliva, and gastric acid. They show extensive diversity in tissue distribution and in their subcellular localization.

Clinical significance

CAIX is a transmembrane protein and is a tumor-associated carbonic anhydrase isoenzyme. It is over-expressed in VHL mutated clear-cell renal cell carcinoma (ccRCC) and hypoxic solid tumors, but is low-expressed in normal kidney and most other normal tissues. It may be involved in cell proliferation and transformation. This gene is mapped to 9p13-p12.

CAIX is a cellular biomarkers of hypoxia. Furthermore, recent studies examining the association between CAIX levels and various clinicopathological outcomes suggest that CAIX expression may also be a valuable prognostic indicator for overall survival although this association has been questioned.

As a drug target

Girentuximab, an antibody to carbonic anhydrase IX, is an investigational agent in clinical trials for renal cell carcinoma.