Carbonic anhydrase IX (CAIX) - a reliable histochemical marker of hypoxia

Mon, 03/09/2015 - 15:03

Carbonic anhydrase IX is a member of the carbonic anhydrase family. This family consists of catalytic enzymes capable of converting carbon dioxide and water into carbonic acid, protons, and bicarbonate ions. This family of molecules is abundantly expressed in all mammalian tissues and helps to govern the pH in normal tissues. CAIX is very stable and found in the membrane. It is also one of the most hypoxically-inducible genes, thus establishing its application as a reliable and consistent hypoxia histochemical marker. CAIX also serves as a useful diagnostic marker for various cancers, notably renal cell carcinoma (RCC). 


Immunohistochemistry: Carbonic Anhydrase IX Antibody [NB100-417] - Renal carcinoma tissue stained with polyclonal carbonic anhydrase IX.

A comprehensive and detailed analysis of prognostic factors in advanced RCC patients from Muriel Lopez et al relied upon an antibody panel that included the CAIX antibody (1). This multivariate study identified the usefulness of molecular markers such as HIF-1alpha, PTEN, p21, thrombocytosis, neutrophilia, and CAIX over other less promising variables. Further follow-up RCC studies from the same researchers involved the development of retrospective patient profiles using the CAIX antibody (2).  This subsequent publication investigated biomarker profiles from advanced RCC patients who also underwent cytokine therapy and/or targeted drug treatments. While CAIX was found to be useful in identifying patients for systemic treatment therapy, PTEN and p21 helped predict sunitinib responders, and thrombocytosis correlated with cytokine responders. Pistollato’s group from the University of Padova mapped networks within highly proliferative glioblastoma multiforme (GBM) tumors, and relied upon the CAIX antibody to correlate intratumoral hypoxia conditions with tumor phenotype and tumor resistance to chemotherapy (3). A group of oncologists also employed the CAIX antibody in their attempts to define appropriate immunohistochemical markers for oral tongue squamous cell carcinoma (SCC) (4). Their disappointing results unfortunately suggest that HIF1-alpha, CAIX, COX2, and Ki-67 are poor markers for this disease. Recently, CAIX expression and extracellular pH levels were measured by Chen’s group at the University of Arizona (5). The CAIX antibody was employed to qualitatively measure CAIX expression in B-cell lymphoma cell line model systems and xenograft tumor models.

Novus Biologicals offers Carbonic anhydrase IX reagents for your research needs including:


  1. 22959659
  2. 22644070
  3. 20309962
  4. 25169079
  5. 25130478

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