Recurrent activating mutation in PRKACA in cortisol-producing adrenal tumors
Adrenal tumors autonomously producing cortisol cause Cushing syndrome1–4. Exome sequencing of 25 tumor-normal pairs revealed two groups. Eight tumors (including 3 carcinomas) had many somatic copy number variants (CNV+) with frequent deletion of CDC42 and CDKN2A, amplification of 5q31.2, and protein-altering mutations in TP53 and RB1. Seventeen (all adenomas) had no CNVs (CNV-), TP53 or RB1 mutations. Six of these had known gain of function mutations in CTNNB15,6 (beta-catenin) or GNAS7,8 (Gαs), Six others had somatic p.Leu206Arg mutations in PRKACA (protein kinase A (PKA) catalytic subunit). Further sequencing identified this mutation in 13 of 63 tumors (35% of adenomas with overt CS). PRKACA, GNAS and CTNNB1 mutations were mutually exclusive. Leu206 directly interacts with PKA’s regulatory subunit, PRKAR1A9,10. PRKACAL206R loses PRKAR1A binding, increasing phosphorylation of downstream targets. PKA activity induces cortisol production and cell proliferation11–15, providing a mechanism for tumor development. These findings define distinct mechanisms underlying adrenal cortisol-producing tumors.
[…] Ribosomal RNA (rRNA) was removed from total RNA using the Ribo-Zero rRNA Removal Kit (Epicenter) according to manufacturer’s instructions. cDNA was synthesized and libraries prepared using the Illumina RNA-Seq kit, followed by sequencing on Illumina HiSeq instrument. RNAseq data for normal adrenal gland was obtained from the Illumina Human Body Map 2.0 Project. Sequences were aligned using TopHat version 2.08 and assembled into transcripts using Cufflinks version 2.0.2,. […]