Exome sequencing identifies recurrent SPOP, FOXA1 and MED12 mutations in prostate cancer

Abstract

Levi Garraway and colleagues report exome sequencing of 112 prostate adenocarcinomas and matched normal tissues. They identify novel recurrent mutations in several genes, including MED12, FOXA1 and SPOP. They find that tumors harboring SPOP mutations lack the TMPRSS2-ERG fusion or other ETS rearrangements, supporting the hypothesis that SPOP mutation is an early driver event in prostate tumorigenesis. Prostate cancer is the second most common cancer in men worldwide and causes over 250,000 deaths each year1. Overtreatment of indolent disease also results in significant morbidity2. Common genetic alterations in prostate cancer include losses of NKX3.1 (8p21)3,4 and PTEN (10q23)5,6, gains of AR (the androgen receptor gene)7,8 and fusion of ETS family transcription factor genes with androgen-responsive promoters9,10,11. Recurrent somatic base-pair substitutions are believed to be less contributory in prostate tumorigenesis12,13 but have not been systematically analyzed in large cohorts. Here, we sequenced the exomes of 112 prostate tumor and normal tissue pairs. New recurrent mutations were identified in multiple genes, including MED12 and FOXA1. SPOP was the most frequently mutated gene, with mutations involving the SPOP substrate-binding cleft in 6–15% of tumors across multiple independent cohorts. Prostate cancers with mutant SPOP lacked ETS family gene rearrangements and showed a distinct pattern of genomic alterations. Thus, SPOP mutations may define a new molecular subtype of prostate cancer.