Endocrinol Metab.  2021 Dec;36(6):1287-1297. 10.3803/EnM.2021.1217.

Clinical and Molecular Characteristics of PRKACA L206R Mutant Cortisol-Producing Adenomas in Korean Patients

• Jang I
• Kim Sj
• Song RY
• Kim K
• Choi S
• Lee JS
• Gwon MK
• Seong MW
• Lee KE
• Kim JH

• KMID: 2523497
• DOI: http://doi.org/10.3803/EnM.2021.1217

Abstract

Background
An activating mutation (c.617A>C/p.Lys206Arg, L206R) in protein kinase cAMP-activated catalytic subunit alpha (PRKACA) has been reported in 35% to 65% of cases of cortisol-producing adenomas (CPAs). We aimed to compare the clinical characteristics and transcriptome analysis between PRKACA L206R mutants and wild-type CPAs in Korea.
Methods
We included 57 subjects with CPAs who underwent adrenalectomy at Seoul National University Hospital. Sanger sequencing for PRKACA was conducted in 57 CPA tumor tissues. RNA sequencing was performed in 13 fresh-frozen tumor tissues.
Results
The prevalence of the PRKACA L206R mutation was 51% (29/57). The mean age of the study subjects was 42±12 years, and 87.7% (50/57) of the patients were female. Subjects with PRKACA L206R mutant CPAs showed smaller adenoma size (3.3±0.7 cm vs. 3.8±1.2 cm, P=0.059) and lower dehydroepiandrosterone sulfate levels (218±180 ng/mL vs. 1,511±3,307 ng/mL, P=0.001) than those with PRKACA wild-type CPAs. Transcriptome profiling identified 244 differentially expressed genes (DEGs) between PRKACA L206R mutant (n=8) and wild-type CPAs (n=5), including five upregulated and 239 downregulated genes in PRKACA L206R mutant CPAs (|fold change| ≥2, P<0.05). Among the upstream regulators of DEGs, CTNNB1 was the most significant transcription regulator. In several pathway analyses, the Wnt signaling pathway was downregulated and the steroid biosynthesis pathway was upregulated in PRKACA mutants. Protein-protein interaction analysis also showed that PRKACA downregulates Wnt signaling and upregulates steroid biosynthesis.
Conclusion
The PRKACA L206R mutation in CPAs causes high hormonal activity with a limited proliferative capacity, as supported by transcriptome profiling.

Keyword

Adrenocortical adenomas; Cushing syndrome; Gene expression profiling; PRKACA mutation; Wnt signaling pathway

Figure

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  Fig. 1 Analysis of differentially expressed genes (DEGs) between protein kinase cAMP-activated catalytic subunit alpha (PRKACA) L206R mutants and wild-type cortisol-producing adenomas (CPAs). (A) Volcano plot of DEGs, showing the magnitude (x-axis) and the statistical significance (y-axis) of differences in gene expression between PRKACA L206R mutants and wild-type CPAs. (B) A t-distributed stochastic neighbor embedding (tSNE) plot. FC, fold change.

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  Fig. 2 Catenin beta 1 (CTNNB1) as an upstream regulator of downregulated genes such as bone morphogenetic protein 4 (BMP4), cyclin D1 (CCND1), lymphoid enhancer binding factor 1 (LEF1), plastin 3 (PLS3), patched 1 (PTCH1), transducer of ERBB2, 2 (TOB2), TSC22 domain family member 1 (TSC22D1), UDP-glucose ceramide glucosyltransferase (UGCG), and versican (VCAN) in protein kinase cAMP-activated catalytic subunit alpha (PRKACA) L206R mutants. Green, downregulation in PRKACA L206R mutants.

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  Fig. 3 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of Cushing syndrome (hsa04934). Red, upregulation in protein kinase cAMP-activated catalytic subunit alpha (PRKACA) L206R mutants; green, downregulation in PRKACA L206R mutants. Steroid hormone biosynthesis, including STAR, CYP11A1, CYP17A1, HSD3B2, and CYP21A, was upregulated, but Wnt signaling-related genes, including Wnt, Frizzled, DVL, glycogen synthase kinase 3 beta (GSK3B), Axin, and TCF/LEF, were downregulated.

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