Recurrent activating mutation in PRKACA in cortisol-producing adrenal tumors

Area of Science:

• Endocrinology
• Cancer Genomics
• Molecular Biology

Background:

• Cushing's syndrome is caused by adrenal tumors that autonomously produce cortisol.
• Understanding the genetic basis of these tumors is crucial for targeted therapies.

Purpose of the Study:

• To identify distinct molecular subgroups within cortisol-producing adrenal tumors.
• To elucidate the underlying genetic mechanisms driving tumor development and cortisol production.

Main Methods:

• Exome sequencing of 25 tumor-normal pairs.
• Analysis of somatic copy number variants (CNVs).
• Identification and characterization of specific gene mutations (TP53, RB1, CTNNB1, GNAS, PRKACA).

Main Results:

• Two distinct tumor subgroups were identified based on genetic profiles.
• Subgroup 1 (8 tumors): Characterized by frequent CNVs, TP53, and RB1 mutations.
• Subgroup 2 (17 tumors): Lacked CNVs and TP53/RB1 mutations; showed mutually exclusive mutations in CTNNB1 (6 tumors), GNAS (6 tumors), or PRKACA (6 tumors, including a novel p.Leu206Arg substitution found in 35% of adenomas).

Conclusions:

• Distinct genetic pathways drive the development of cortisol-producing adrenal tumors.
• Mutations in PRKACA, GNAS, and CTNNB1 lead to increased protein kinase A (PKA) activity, promoting cortisol production and proliferation.
• The p.Leu206Arg PRKACA mutation disrupts PKA regulation, offering a new mechanistic insight into adrenal tumorigenesis.