Endocrine Abstracts

Protein Kinase A (PKA) consists of two catalytic and two regulatory subunits with several isoforms (Cα, β, γ and RIα, IIα, Iβ, IIβ, respectively). Type II regulatory subunits are phosphorylated by PKA in their inhibitory sites, while type I are not. Somatic activating mutations in the gene encoding the catalytic subunit α (Cα) of PKA (PRKACA) have been found in 30–40% of cortisol-producing adrenocortical adenomas (CPA). We rece...

We previously identified mutations in PRKACA, coding for the catalytic a (Ca) subunit of protein kinase A (PKA), as the main genetic alteration in cortisol-producing adrenal adenomas (CPAs) responsible for Cushing’s syndrome. Here, we further investigated the mechanism of action of all PRKACA mutations identified so far by our team (L206R, L199_C200_insW, S213R_L212_K214insIILR, C200_GlyinsV, W197R, del244-248+E249Q and E32V). Five out of seven mutants s...

Previously, we identified seven mutations in the main catalytic subunit of protein kinase A (PKA Cα) to be responsible for cortisol-secreting adrenocortical adenomas (CPAs): L206R, L199_C200_insW, S213R_L212_K214insIILR, C200_GlyinsV, W197R, del244-248+E249Q, E32V. Here we performed a functional characterization of these mutants. Specifically, we evaluated the association between PKA regulatory and catalytic subunits using co-immunoprecipitation and PKA activity using a k...

Recently, somatic, heterozygous mutations in the gene encoding the deubiquitinase USP8 have been identified in 30–60% of corticotroph tumors. These mutations were found to hinder binding of 14-3-3 proteins, increasing its deubiquitinating activity. One substrate is Epidermal Growth Factor Receptor (EGFR), USP8 triggering EGFR recycling and increased EGFR signaling. However, tumors harboring mutations in USP8 are smaller than WT tumors, raising the debate if EGFR, as a pot...

Protein Kinase A (PKA) consists of two catalytic and two regulatory subunits with several isoforms (Cα,β,γ, RIα,IIα,Iβ,IIβ). In 30–40% of cortisol-producing adrenocortical adenomas (CPA) heterozygous activating somatic mutations in the catalytic subunit α (Cα) of PKA have been found. Previous reports found strikingly reduced levels of RIIβ in CPA compared to other adrenocortical tumors. Here, we investigated the correlatio...

Recently, somatic, heterozygous mutations in the gene encoding the deubiquitinase USP8 have been identified in 30–60% of corticotroph tumors. These mutations were found to hinder binding of 14-3-3 proteins, increasing its deubiquitinating activity. One substrate is Epidermal Growth Factor Receptor (EGFR), USP8 triggers EGFR recycling and increased EGFR signaling. However, tumors harboring mutations in USP8 are smaller than WT tumors, raising the debate if EGFR, as a poten...

Context: Mitotane is the only drug approved for treatment of adrenocortical carcinoma (ACC) and in clinical use for more than 50 years. Mitotane counteracts both tumour growth and tumoral steroid hormone production but treatment is associated with severe side effects. The molecular mechanism of mitotane is still unknown, which hampers progress in treatment of ACC.Objective: To identify the mechanism of action and molecular target of mitotane.<p class...