Q
Carbonic anhydrase IX is most likely to be expressed by which type of renal cell carcinoma (RCC)?
Correct Answer:
Explanation
Carbonic anhydrase IX (CAIX) is a transmembrane protein that is expressed in a number of different cancers including clear cell RCC, clear cell papillary RCC and mesothelioma. It is also sometimes positive in urothelial carcinoma, squamous cell carcinoma, pancreatic, gastric and colonic adenocarcinoma.
It is regulated by hypoxia-inducible factor 1 alpha (HIF1-α) which is bound to Von Hippel Lindau protein (pVHL). In the case of ccRCC up to 95% of the tumor genomes are constitutionally VHL gene muted or deleted, thus leading to constitutive activation of HIF1 and CAIX upregulation, even in normoxic conditions.
