PBRM1 and BAP1 as novel targets for renal cell carcinoma

Technological advances in genome sequencing have led to the identification of novel driver genes mutated in renal cancer. Hitherto, 1 gene was known to be frequently mutated in renal cell carcinoma of clear cell type (ccRCC), the von Hippel-Lindau (VHL) gene. VHL was identified by positional cloning as the gene responsible for a familial syndrome with renal cancer predisposition, von Hippel-Lindau. Subsequently, VHL was found to be inactivated in approximately 90% of sporadic ccRCC. The discovery of VHL, together with the elucidation of its function, transformed the treatment of ccRCC leading to the introduction of 5 new drugs into the clinic. However, no other familial ccRCC predisposing genes are frequently mutated in sporadic ccRCC. With the development of massively parallel sequencing, a plethora of somatically mutated genes has been identified. Most genes are mutated at low frequencies, but 3 genes are mutated in more than 10% of ccRCC, PBRM1 (mutated in ~50%), BAP1 (~15%), and SETD2 (~15%). Like VHL, all 3 genes are 2-hit tumor suppressor genes. Furthermore, these 3 genes are within a 50-Mb region on the short arm of chromosome 3p that encompasses VHL and is deleted in ~90% of ccRCC. We discovered that PBRM1 mutations tend to anticorrelate with BAP1 mutations in ccRCC and that PBRM1- and BAP1-mutated tumors exhibit different biology and are associated with markedly different outcomes. This established the foundation for the first molecular genetic classification of sporadic ccRCC. Herein, I review the evidence that implicated PBRM1 and BAP1 as renal cancer driver genes, provide an update on the function of the gene products, and speculate on how mutations in these genes may be exploited therapeutically.