Gene Summary

Gene:PRKAR1A; protein kinase cAMP-dependent type I regulatory subunit alpha
Summary:cAMP is a signaling molecule important for a variety of cellular functions. cAMP exerts its effects by activating the cAMP-dependent protein kinase, which transduces the signal through phosphorylation of different target proteins. The inactive kinase holoenzyme is a tetramer composed of two regulatory and two catalytic subunits. cAMP causes the dissociation of the inactive holoenzyme into a dimer of regulatory subunits bound to four cAMP and two free monomeric catalytic subunits. Four different regulatory subunits and three catalytic subunits have been identified in humans. This gene encodes one of the regulatory subunits. This protein was found to be a tissue-specific extinguisher that down-regulates the expression of seven liver genes in hepatoma x fibroblast hybrids. Mutations in this gene cause Carney complex (CNC). This gene can fuse to the RET protooncogene by gene rearrangement and form the thyroid tumor-specific chimeric oncogene known as PTC2. A nonconventional nuclear localization sequence (NLS) has been found for this protein which suggests a role in DNA replication via the protein serving as a nuclear transport protein for the second subunit of the Replication Factor C (RFC40). Several alternatively spliced transcript variants encoding two different isoforms have been observed. [provided by RefSeq, Jan 2013]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:cAMP-dependent protein kinase type I-alpha regulatory subunit
Source:NCBIAccessed: 11 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: PRKAR1A (cancer-related)

Papanastasiou L, Fountoulakis S, Voulgaris N, et al.
Identification of a novel mutation of the PRKAR1A gene in a patient with Carney complex with significant osteoporosis and recurrent fractures.
Hormones (Athens). 2016 Jan-Mar; 15(1):129-35 [PubMed] Related Publications
OBJECTIVE: Carney complex (CNC) is a rare autosomal dominant multiple neoplasia syndrome characterized by the presence of endocrine and non-endocrine tumors. More than 125 different germline mutations of the protein Kinase A type 1-α regulatory subunit (PRKAR1A) gene have been reported. We present a novel PRKAR1A gene germline mutation in a patient with severe osteoporosis and recurrent vertebral fractures.
DESIGN: Clinical case report.
CASE REPORT: A 53-year-old male with a medical history of surgically removed recurrent cardiac myxomas was evaluated for repeated low-pressure vertebral fractures and severe osteoporosis. Physical examination revealed spotty skin pigmentation of the lower extremities and papules in the nuchal and thoracic region. The presence of hypercortisolism due to micronodular adrenal disease and the history of cardiac myxomas suggested the diagnosis of CNC; the patient underwent detailed imaging investigation and genetic testing.
METHODS: Standard imaging and clinical testing; DNA was sequenced by the Sanger method.
RESULTS: Sequence analysis from peripheral lymphocytes DNA revealed a novel heterozygous point mutation at codon 172 of exon 2 (c.172G>T) of the PRKAR1A gene, resulting in early termination of the PRKAR1A transcript [p.Glu58Ter (E58X)].
CONCLUSION: We report a novel point mutation of the PRKAR1A gene in a patient with CNC who presented with significant osteoporosis and fractures. Low bone mineral density along with recurrent myxomas should point to the diagnosis of CNC.

Massobrio L, Nasti S, Martinuzzi C, et al.
Mutation Analysis of PRKAR1A Gene in a Patient with Atrial Myxoma.
Clin Lab. 2016; 62(4):731-4 [PubMed] Related Publications
BACKGROUND: Intracardiac myxomas are frequent benign tumors of the heart and typically localize in the left atri- um and interatrial septum. When myxomas generate at other sites, they are designated as atypical. Mutations in the PRKAR1A gene (a tumor suppressor gene that encodes a protein kinase A [PKA] regulatory 1-alpha subunit) have been identified in both syndromic and non-syndromic cardiac atypical myxomas.
METHODS: We report the case of a 33-year old woman suffering from night fever, weight loss, asthenia, and progressive dyspnea.
RESULTS: The blood laboratory tests revealed microcytic anemia, leukocytosis, thrombocytosis, increased serum levels of C-reactive protein level, and negative blood cultures. Physical examination also demonstrated a 2/6 systolic murmur. Transthoracic and trans-esophageal echocardiography showed a voluminous, mobile mass in the left atrium with a secondary dynamic obstruction of the left cardiac chamber and a significant functional mitral stenosis. A myxoma was supposed and the patient underwent surgery. Histologically, the lesion was identified as myxomatous tumor with gelatinous pattern. No germline mutations of the PRKAR1A gene were detected. The postoperative course did not present any complications, and the patient was discharged on the sixth postoperative day in good clinical condition. Accordingly, there was an improvement in the laboratory tests' results and a resolution of symptoms.
CONCLUSIONS: The patient presented an atrial giant gelatinous myxoma with peculiarity of fever of unknown origin, without PRKAR1A gene germline mutations.

Peculis R, Balcere I, Rovite V, et al.
Polymorphisms in MEN1 and DRD2 genes are associated with the occurrence and characteristics of pituitary adenomas.
Eur J Endocrinol. 2016; 175(2):145-53 [PubMed] Related Publications
OBJECTIVE: Although pituitary adenomas (PAs) affect a significant proportion of the population, only a fraction have the potential to become clinically relevant during an individual's lifetime, causing hormonal imbalance or complications due to mass effect. The overwhelming majority of cases are sporadic and without a clear familial history, and the genotype-phenotype correlation in PA patients is poorly understood. Our aim was to investigate the involvement of genes known for their role in familial cases on drug response and tumor suppression in the development and pathology of PAs in a patient group from Latvia.
DESIGN: The study included 143 cases and 354 controls, we investigated the role of single-nucleotide polymorphisms (SNPs) in seven genes (SSTR2, SSTR5, DRD2, MEN1, AIP, GNAS, and PRKAR1A) associated with pituitary tumor occurrence, phenotype, and clinical symptoms.
METHODS: Genotyping of 96 tag and nonsynonymous SNPs was performed in the genomic regions of interest.
RESULTS: We discovered a significant association (OR=17.8, CI 0.95=2.18-145.5, P=0.0002) between a rare MEN1 mutation (rs2959656) and clinically active adenoma in our patients. Additionally, rs7131056 at DRD2 was associated with a higher occurrence of extrasellar growth in patients with prolactinoma and somatotropinoma (OR=2.79, CI 0.95=1.58-4.95, P=0.0004).
CONCLUSIONS: rs2959656, a nonsynonymous variant in MEN1, is associated with the development of clinically active PA. Furthermore, rs7131056 in DRD2 contributes to either faster growth of the adenoma or reduced symptomatic presentation, allowing PAs to become larger before detection.

Angelousi A, Zilbermint M, Berthon A, et al.
Diagnosis and Management of Hereditary Adrenal Cancer.
Recent Results Cancer Res. 2016; 205:125-47 [PubMed] Related Publications
Benign adrenocortical tumours (ACT) are relatively frequent lesions; on the contrary, adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with unfavourable prognosis. Recent advances in the molecular understanding of adrenal cancer offer promise for better therapies in the future. Many of these advances stem from the molecular elucidation of genetic conditions predisposing to the development of ACC. Six main clinical syndromes have been described to be associated with hereditary adrenal cancer. In these conditions, genetic counselling plays an important role for the early detection and follow-up of the patients and the affected family members.

Bano G, Hodgson S
Diagnosis and Management of Hereditary Thyroid Cancer.
Recent Results Cancer Res. 2016; 205:29-44 [PubMed] Related Publications
Thyroid cancers are largely divided into medullary (MTC) and non-medullary (NMTC) cancers , depending on the cell type of origin. Familial non-medullary thyroid cancer (FNMTC) comprises about 5-15% of NMTC and is a heterogeneous group of diseases, including both non-syndromic and syndromic forms. Non-syndromic FNMTC tends to manifest papillary thyroid carcinoma , usually multifocal and bilateral . Several high-penetrance genes for FNMTC have been identified, but they are often confined to a few or single families, and other susceptibility loci appear to play a small part, conferring only small increments in risk. Familial susceptibility is likely to be due to a combination of genetic and environmental influences. The current focus of research in FNMTC is to characterise the susceptibility genes and their role in carcinogenesis. FNMTC can also occur as a part of multitumour genetic syndromes such as familial adenomatous polyposis , Cowden's disease , Werner's syndrome and Carney complex . These tend to present at an early age and are multicentric and bilateral with distinct pathology. The clinical evaluation of these patients is similar to that for most patients with a thyroid nodule. Medullary thyroid cancer (MTC) arises from the parafollicular cells of the thyroid which release calcitonin. The familial form of MTC accounts for 20-25% of cases and presents as a part of the multiple endocrine neoplasia type 2 (MEN 2) syndromes or as a pure familial MTC (FMTC). They are caused by germline point mutations in the RET oncogene on chromosome 10q11.2. There is a clear genotype-phenotype correlation, and the aggressiveness of FMTC depends on the specific genetic mutation, which should determine the timing of surgery.

Minnetti M, Grossman A
Somatic and germline mutations in NETs: Implications for their diagnosis and management.
Best Pract Res Clin Endocrinol Metab. 2016; 30(1):115-27 [PubMed] Related Publications
It is now understood that specific somatic and germline mutations may lead to the development of the neuroendocrine tumours (NETs). NETs usually occur as sporadic isolated tumours, although they also may present as part of complex familial endocrine cancer syndromes, such as multiple endocrine neoplasia type 1 (MEN1) and type 2 (MEN2), Von Hippel-Lindau (VHL) and neurofibromatosis syndromes, tuberous sclerosis, Carney triad and dyad, Reed syndrome and polycythaemia-paraganglioma syndromes. Only in MEN2 syndrome is there a specific genotype-phenotype correlation, although in both sporadic and syndromic NETs some gene mutations are associated with specific clinico-pathological features and prognosis. There have been several advances in our understanding of the NETs leading to earlier detection and targeted therapeutic treatment, but given the poor prognosis associated with metastatic NETs, it will be necessary to find new biomarkers for the prediction of malignant potential and to find novel therapeutic targets for NETs.

Guo H, Xiong H, Li Z, et al.
Association of Carney Complex with an Intronic Splice Site Mutation in the PRKAR1A Gene.
Horm Metab Res. 2016; 48(6):384-8 [PubMed] Related Publications
This study was aimed to investigate the clinical features and mutations in the PRKAR1A gene of a multigenerational kindred including 17 individuals at risk for Carney complex. Eight patients were diagnosed with Carney complex among the 17 individuals (47.1%). Among the 8 affected patients, 4 had cardiac myxomas, 8 had skin pigmentation, and 3 had diabetes. Genomic DNA sequencing in 14 surviving patients showed 6 had the same germline mutation in the sixth intron and affected the splice site. cDNA sequencing and DNAMAN software showed 159 bases were absent, resulting in the absence of the amino acids 249 to 301 from the protein. All 6 patients with this PRKAR1A gene mutation had skin pigmentation. In conclusion, the present study reported for the first time an intronic splice site mutation in the PRKAR1A gene of a Chinese family with Carney complex, which probably caused skin pigmentation observed in affected family members.

Burke A, Tavora F
The 2015 WHO Classification of Tumors of the Heart and Pericardium.
J Thorac Oncol. 2016; 11(4):441-52 [PubMed] Related Publications
This article reviews the nomenclature of benign and malignant neoplasm of the heart and pericardium in the 4th edition of the World Health Organization's Classification, with emphasis on differences since the 3rd edition of 2004. The tumours are divided into benign, malignant, and intermediate tumors of uncertain behavior, with separate sections on germ cell tumours and tumors of the pericardium. There are important updates in the sarcoma classification, with emphasis on the most common site, the left atrium. The importance of the new genetic finding in cardiac myxomas, namely somatic mutations in the PRKAR1A gene underscores the importance of this alteration in the pathogenesis of these tumors. Challenges on the classification of each entity are discussed.

Richter S, Klink B, Nacke B, et al.
Epigenetic Mutation of the Succinate Dehydrogenase C Promoter in a Patient With Two Paragangliomas.
J Clin Endocrinol Metab. 2016; 101(2):359-63 [PubMed] Related Publications
CONTEXT: Mutational inactivation of the succinate dehydrogenase (SDH) complex is a well-described cause of tumor development in pheochromocytomas/paragangliomas (PPGLs) and gastrointestinal stromal tumors (GISTs). Epigenetic inactivation of the SDHC gene is a more recently discovered phenomenon, which so far has only been described in GISTs and PPGLs from patients with Carney triad syndrome.
CASE DESCRIPTION: A 33-year-old patient presented with two abdominal paragangliomas (PGLs) and an adrenocortical adenoma. Both PGLs showed high succinate:fumarate ratios indicative of SDHx mutations; however, no mutations in any of the known PPGL susceptibility genes were found in leucocyte or tumor DNA. We identified methylation of the SDHC promoter region in both PGLs, which coincided with decreased SDHC expression at mRNA and protein levels and a hypermethylated epigenomic signature (CpG island methylator phenotype). Low-level SDHC promoter methylation was also observed in the adenoma but not in normal adrenal tissue or blood, suggesting postzygotic somatic mosaicism for SDHC promoter methylation in the patient.
CONCLUSIONS: This report provides evidence that SDHC promoter methylation can cause PGLs due to SDHC inactivation, emphasizing the importance of considering epigenetic changes and functional readouts in the genetic evaluation of patients not only with GISTs and Carney triad but also with PPGL.

Mullany LE, Wolff RK, Herrick JS, et al.
SNP Regulation of microRNA Expression and Subsequent Colon Cancer Risk.
PLoS One. 2015; 10(12):e0143894 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: MicroRNAs (miRNAs) regulate messenger RNAs (mRNAs) and as such have been implicated in a variety of diseases, including cancer. MiRNAs regulate mRNAs through binding of the miRNA 5' seed sequence (~7-8 nucleotides) to the mRNA 3' UTRs; polymorphisms in these regions have the potential to alter miRNA-mRNA target associations. SNPs in miRNA genes as well as miRNA-target genes have been proposed to influence cancer risk through altered miRNA expression levels.
METHODS: MiRNA-SNPs and miRNA-target gene-SNPs were identified through the literature. We used SNPs from Genome-Wide Association Study (GWAS) data that were matched to individuals with miRNA expression data generated from an Agilent platform for colon tumor and non-tumor paired tissues. These samples were used to evaluate 327 miRNA-SNP pairs for associations between SNPs and miRNA expression levels as well as for SNP associations with colon cancer.
RESULTS: Twenty-two miRNAs expressed in non-tumor tissue were significantly different by genotype and 21 SNPs were associated with altered tumor/non-tumor differential miRNA expression across genotypes. Two miRNAs were associated with SNP genotype for both non-tumor and tumor/non-tumor differential expression. Of the 41 miRNAs significantly associated with SNPs all but seven were significantly differentially expressed in colon tumor tissue. Two of the 41 SNPs significantly associated with miRNA expression levels were associated with colon cancer risk: rs8176318 (BRCA1), ORAA 1.31 95% CI 1.01, 1.78, and rs8905 (PRKAR1A), ORGG 2.31 95% CI 1.11, 4.77.
CONCLUSION: Of the 327 SNPs identified in the literature as being important because of their potential regulation of miRNA expression levels, 12.5% had statistically significantly associations with miRNA expression. However, only two of these SNPs were significantly associated with colon cancer.

Saloustros E, Salpea P, Qi CF, et al.
Hematopoietic neoplasms in Prkar2a-deficient mice.
J Exp Clin Cancer Res. 2015; 34:143 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Protein kinase A (PKA) is a holoenzyme that consists of a dimer of regulatory subunits and two inactive catalytic subunits that bind to the regulatory subunit dimer. Four regulatory subunits (RIα, RIβ, RIIα, RIIβ) and four catalytic subunits (Cα, Cβ, Cγ, Prkx) have been described in the human and mouse genomes. Previous studies showed that complete inactivation of the Prkar1a subunit (coding for RIα) in the germline leads to embryonic lethality, while Prkar1a-deficient mice are viable and develop schwannomas, thyroid, and bone neoplasms, and rarely lymphomas and sarcomas. Mice with inactivation of the Prkar2a and Prkar2b genes (coding for RIIα and RIIβ, respectively) are also viable but have not been studied for their susceptibility to any tumors.
METHODS: Cohorts of Prkar1a (+/-) , Prkar2a (+/-) , Prkar2a (-/-) , Prkar2b (+/-) and wild type (WT) mice have been observed between 5 and 25 months of age for the development of hematologic malignancies. Tissues were studied by immunohistochemistry; tumor-specific markers were also used as indicated. Cell sorting and protein studies were also performed.
RESULTS: Both Prkar2a (-/-) and Prkar2a (+/-) mice frequently developed hematopoietic neoplasms dominated by histiocytic sarcomas (HS) with rare diffuse large B cell lymphomas (DLBCL). Southern blot analysis confirmed that the tumors diagnosed histologically as DLBCL were clonal B cell neoplasms. Mice with other genotypes did not develop a significant number of similar neoplasms.
CONCLUSIONS: Prkar2a deficiency predisposes to hematopoietic malignancies in vivo. RIIα's likely association with HS and DLBCL was hitherto unrecognized and may lead to better understanding of these rare neoplasms.

Xie K, Ma H, Liang C, et al.
A functional variant in miR-155 regulation region contributes to lung cancer risk and survival.
Oncotarget. 2015; 6(40):42781-92 [PubMed] Free Access to Full Article Related Publications
Emerging evidence suggested that upregulation of miR-155 could serve as a promising marker for the diagnosis and prognosis of non-small cell lung cancer (NSCLC). In the present study, we genotyped rs767649 (A > T) located in miR-155 regulation region in 1341 cases and 1982 controls, and analyzed the associations of rs767649 with NSCLC risk and survival. Consequently, rs767649 exhibited the significant associations with the risk (adjusted OR = 1.12, 95% CI = 1.01-1.24, P = 0.031) and prognosis of NSCLC (adjusted HR = 1.17, 95% CI = 1.03-1.32, P = 0.014). Meanwhile, rs767649 specifically interacted with radio-chemotherapy (P(int) = 0.013), and patients with both the rs767649-TT genotype and radio-chemotherapy had the highest hazard ratio (adjusted HR = 1.65, 95% CI = 1.26-2.16, P < 0.001). Furthermore, using functional assays and The Cancer Genome Atlas (TCGA) Lung Adenocarcinoma (LUAD) dataset, we found that rs767649 variant allele could increase the transcriptional activity of miR-155, which in turn facilitated tumor growth and metastasis by inhibiting HBP1, TJP1, SMAD5 and PRKAR1A expression. Our findings suggested that rs767649 A > T might contribute to the increased risk and poor prognosis of NSCLC, highlighting the importance of rs767649 in the prevention and therapy of NSCLC.

Heck D, Wortmann S, Kraus L, et al.
Role of Endocrine Gland-Derived Vascular Endothelial Growth Factor (EG-VEGF) and Its Receptors in Adrenocortical Tumors.
Horm Cancer. 2015; 6(5-6):225-36 [PubMed] Free Access to Full Article Related Publications
Angiogenesis is essential for tumor growth and metastasis. Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is an angiogenic factor predominantly expressed in steroidogenic organs like the adrenal gland, ovary, testes, and placenta. EG-VEGF has antiapoptotic, mitogenic, and chemoattractive properties mediated via the two G protein-coupled receptors prokineticin receptor 1 (PKR1) and prokineticin receptor 2 (PKR2). We investigated the expression of EG-VEGF and its receptors in a large number of normal adrenal glands (NAG), adrenocortical adenomas (ACA), and carcinomas (ACC) using real-time PCR (NAG, n = 12; ACA, n = 24; and ACC, n = 30) and immunohistochemistry (NAG, n = 9; ACA, n = 23; and ACC, n = 163) and evaluated its impact on patients' survival. EG-VEGF, PKR1, and PKR2 mRNA and protein are expressed in NAG and the vast majority of ACA and ACC samples. The mean EG-VEGF mRNA expression was significantly lower in ACC (606.5 ± 77.1 copies) compared to NAG (4,043 ± 1,111) and cortisol-producing adenomas (CPA) (4,433 ± 2,378) (p < 0.01 and p < 0.05, respectively). However, cytoplasmic and nuclear EG-VEGF protein expression was either significantly higher or similar in ACC (H score 2.4 ± 0.05, p < 0.05 and 1.7 ± 0.08, n.s., respectively) compared to NAG (1.8 ± 0.14 and 1.7 ± 0.2). Nuclear protein expression of either EG-VEGF or PKR1 or both is predictive for a higher mortality compared to patients without nuclear expression (hazard ratio (HR) = 5.15; 95% confidence interval (CI) = 1.24-21.36, n = 100, p = 0.02 independent of age, sex, and tumor stage). These findings suggest that EG-VEGF and its receptor PKR1 might play a role in the pathogenesis of adrenocortical tumors and could serve as prognostic markers for this rare malignant disease.

Choi YJ, Jung SH, Kim MS, et al.
Genomic landscape of endometrial stromal sarcoma of uterus.
Oncotarget. 2015; 6(32):33319-28 [PubMed] Free Access to Full Article Related Publications
Although recurrent gene fusions such as JAZF1-JJAZ1 are considered driver events for endometrial stromal sarcoma (ESS) development, other genomic alterations remain largely unknown. In this study, we performed whole-exome sequencing, transcriptome sequencing and copy number profiling for five ESSs (three low-grade ESS (LG-ESS) and two undifferentiated uterine sarcomas (UUSs)). All three LG-ESSs exhibited either one of JAZF1-SUZ12, JAZF1-PHF1 and MEAF6-PHF1 fusions, whereas the two UUSs did not. All ESSs except one LG-ESS exhibited copy number alterations (CNAs), many of which encompassed cancer-related genes. In UUSs, five CNAs encompassing cancer-related genes (EZR, CDH1, RB1, TP53 and PRKAR1A) accompanied their expressional changes, suggesting that they might stimulate UUS development. We found 81 non-silent mutations (35 from LG-ESSs and 46 from UUSs) that included 15 putative cancer genes catalogued in cancer-related databases, including PPARG and IRF4 mutations. However, they were non-recurrent and did not include any well-known mutations, indicating that point mutations may not be a major driver for ESS development. Our data show that gene fusions and CNAs are the principal drivers for LG-ESS and USS, respectively, but both may require additional genomic alterations including point mutations. These differences may explain the different biologic behaviors between LG-ESS and UUS. Our findings suggest that ESS development requires point mutations and CNAs as well as the gene fusions.

Sun Y, Chen X, Sun J, et al.
A Novel Inherited Mutation in PRKAR1A Abrogates PreRNA Splicing in a Carney Complex Family.
Can J Cardiol. 2015; 31(11):1393-401 [PubMed] Related Publications
BACKGROUND: Carney complex (CNC) is an autosomal dominant inherited disease, characterized by spotty skin pigmentation, cardiac and cutaneous myxomas, and endocrine overactivity. We report on a Chinese CNC family with a novel mutation in the protein kinase A regulatory subunit 1 (PRKAR1A) gene.
METHODS: Target-exome sequencing was performed to identify the mutation of PRKAR1A in 2 members of the CNC family.
RESULTS: The proband was a young man with typical CNC, including pigmentation, cutaneous myxomas, cardiac myxoma, Sertoli cell tumour of his left testis, and multiple hypoechoic thyroid nodules. His mother also had CNC with skin pigmentation, cutaneous myxomas, and a cardiac myxoma. Target-exome capture analysis revealed that the proband and the mother carried a novel heterozygous mutation in the exon 6 splicing donor site of PRKAR1A. Sequencing analysis of myxoma messenger RNA revealed that the mutation abrogated exon 6 preRNA splicing, leading to a frameshift starting at Valine 185 and premature translation termination in intron 6. The truncated enzyme lacks the functional cyclic adenosine monophosphate (cAMP) binding domain at the C-terminus, causing PRKAR1A haploinsufficiency.
CONCLUSIONS: In this study we report on a novel splicing mutation in the PRKAR1A gene that adds to the genetic heterogeneity of CNC.

Rhayem Y, Le Stunff C, Abdel Khalek W, et al.
Functional Characterization of PRKAR1A Mutations Reveals a Unique Molecular Mechanism Causing Acrodysostosis but Multiple Mechanisms Causing Carney Complex.
J Biol Chem. 2015; 290(46):27816-28 [PubMed] Free Access to Full Article Related Publications
The main target of cAMP is PKA, the main regulatory subunit of which (PRKAR1A) presents mutations in two genetic disorders: acrodysostosis and Carney complex. In addition to the initial recurrent mutation (R368X) of the PRKAR1A gene, several missense and nonsense mutations have been observed recently in acrodysostosis with hormonal resistance. These mutations are located in one of the two cAMP-binding domains of the protein, and their functional characterization is presented here. Expression of each of the PRKAR1A mutants results in a reduction of forskolin-induced PKA activation (measured by a reporter assay) and an impaired ability of cAMP to dissociate PRKAR1A from the catalytic PKA subunits by BRET assay. Modeling studies and sensitivity to cAMP analogs specific for domain A (8-piperidinoadenosine 3',5'-cyclic monophosphate) or domain B (8-(6-aminohexyl)aminoadenosine-3',5'-cyclic monophosphate) indicate that the mutations impair cAMP binding locally in the domain containing the mutation. Interestingly, two of these mutations affect amino acids for which alternative amino acid substitutions have been reported to cause the Carney complex phenotype. To decipher the molecular mechanism through which homologous substitutions can produce such strikingly different clinical phenotypes, we studied these mutations using the same approaches. Interestingly, the Carney mutants also demonstrated resistance to cAMP, but they expressed additional functional defects, including accelerated PRKAR1A protein degradation. These data demonstrate that a cAMP binding defect is the common molecular mechanism for resistance of PKA activation in acrodysosotosis and that several distinct mechanisms lead to constitutive PKA activation in Carney complex.

Best-Rocha A, Patel K, Hicks J, et al.
Novel Association of Odontogenic Myxoma with Constitutional Chromosomal 1q21 Microduplication: Case Report and Review of the Literature.
Pediatr Dev Pathol. 2016 Mar-Apr; 19(2):139-45 [PubMed] Related Publications
Odontogenic myxoma (OM) is a rare, benign, and locally aggressive tumor. It tends to occur in the posterior maxilla and mandible and is often associated with root resorption and perforation of cortex. Histopathologically, there is a proliferation of spindle, bipolar, and stellate cells, with bland nuclei within a myxoid to infrequently fibromyxoid extracellular matrix. Long, thin residual bony trabeculae are often seen floating within the spindle cell proliferation because of the infiltrating nature of this tumor, and these trabeculae impart a "soap bubble" or "tennis-racket" radiologic appearance. No syndromic association of OM has been reported. Although similar histopathologic features are shared with cardiac myxoma and soft tissue myxoma, mutations in the GNAS gene have not been identified in OM to date, and only 2 of 17 OMs showed mutations in the PRKAR1A gene. In this report, we describe a case of OM in a patient with constitutional 1q21 microduplication, a locus that harbors genes encoding certain proteins in the cAMP-dependent protein kinase A (PKA) signaling pathway, including G-protein-coupled receptors and 1 phosphodiesterase interacting protein. Review of the literature describes the key clinical features and molecular pathogenesis of 1q21 microduplication, as well as highlighting the role of PKA signaling pathway in the pathogenesis of myxomas in general.

Sigloch FC, Burk UC, Biniossek ML, et al.
miR-200c dampens cancer cell migration via regulation of protein kinase A subunits.
Oncotarget. 2015; 6(27):23874-89 [PubMed] Free Access to Full Article Related Publications
Expression of miR-200c is a molecular switch to determine cellular fate towards a mesenchymal or epithelial phenotype. miR-200c suppresses the early steps of tumor progression by preventing epithelial-mesenchymal transition (EMT) and intravasation of tumor cells. Unraveling the underlying molecular mechanisms might pinpoint to novel therapeutic options. To better understand these mechanisms it is crucial to identify targets of miR-200c. Here, we employ a combination of quantitative proteomic and bioinformatic strategies to identify novel miR-200c targets. We identify and confirm two subunits of the central cellular kinase protein kinase A (PKA), namely PRKAR1A and PRKACB, to be directly regulated by miR-200c. Notably, siRNA-mediated downregulation of both proteins phenocopies the migratory behavior of breast cancer cells after miR-200c overexpression. Patient data from publicly accessible databases supports a miR-200c-PKA axis. Thus, our study identifies the PKA heteroprotein as an important mediator of miR-200c induced repression of migration in breast cancer cells. By bioinformatics, we define a miRNA target cluster consisting of PRKAR1A, PRKAR2B, PRKACB, and COF2, which is targeted by a group of 14 miRNAs.

Correa R, Salpea P, Stratakis CA
Carney complex: an update.
Eur J Endocrinol. 2015; 173(4):M85-97 [PubMed] Free Access to Full Article Related Publications
Carney complex (CNC) is a rare autosomal dominant syndrome, characterized by pigmented lesions of the skin and mucosa, cardiac, cutaneous and other myxomas and multiple endocrine tumors. The disease is caused by inactivating mutations or large deletions of the PRKAR1A gene located at 17q22-24 coding for the regulatory subunit type I alpha of protein kinase A (PKA) gene. Most recently, components of the complex have been associated with defects of other PKA subunits, such as the catalytic subunits PRKACA (adrenal hyperplasia) and PRKACB (pigmented spots, myxomas, pituitary adenomas). In this report, we review CNC, its clinical features, diagnosis, treatment and molecular etiology, including PRKAR1A mutations and the newest on PRKACA and PRKACB defects especially as they pertain to adrenal tumors and Cushing's syndrome.

Zhang YL, Wang XC, Yu W, et al.
A case of familial Carney complex.
Arch Iran Med. 2015; 18(5):324-8 [PubMed] Related Publications
Carney complex is a syndrome characterized by skin pigmentation abnormalities, myxomas, endocrine tumors/overactivity, and schwannomas. It is caused by a mutation in the PRKAR1A gene that encodes the enzyme protein kinase A regulatory subunit type 1 alpha. A 23-year old male was diagnosed with Carney complex on the basis of spotty skin lentigines on his face and lips, multiple thyroid neoplasms, a right ventricular myxoma, and bilateral testicular tumors. A total bilateral orchectomy was performed and the pathological findings revealed Leydig's cell tumors on one side and a Sertoli cell tumor on the other side. When his first-degree relatives were examined, his mother was found to have Carney complex as well. This is the first reported case of familial Carney complex in China.

Guo H, Xu J, Xiong H, Hu S
Case studies of two related Chinese patients with Carney complex presenting with extensive cardiac myxomas and PRKAR1A gene mutation of c.491_492delTG.
World J Surg Oncol. 2015; 13:83 [PubMed] Free Access to Full Article Related Publications
Carney complex is an autosomal dominant disease that is clinically characterized by cardiac myxomas, spotty skin pigmentation, and endocrine overactivity. Carney complex is most commonly caused by mutations in the PRKAR1A gene on chromosome 17q22-24. Currently, there are at least 117 pathogenic mutations in PRKAR1A that have been identified. Herein, we report on two cases of Carney complex in related Chinese patients with a c.491_492delTG mutation that presented with multiple and extensive cardiac myxomas and skin pigmentation.

Zilbermint M, Stratakis CA
Protein kinase A defects and cortisol-producing adrenal tumors.
Curr Opin Endocrinol Diabetes Obes. 2015; 22(3):157-62 [PubMed] Free Access to Full Article Related Publications
PURPOSE OF REVIEW: Cushing syndrome caused by cortisol-producing adrenal adenomas is a rare condition, associated with high morbidity due to weight gain, diabetes mellitus, osteoporosis, hypertension, muscle weakness, mood disturbance and others. The first gene to be identified as causative of Cushing syndrome was PRKAR1A. We present an update on protein kinase A (PKA) defects and Cushing syndrome.
RECENT FINDINGS: The cyclic AMP-dependent PKA catalytic subunit alpha (PRKACA) hotspot point mutation (c.617A > C [p.Leu206Arg]), leading to an increase of basal PKA activity, and formation of cortisol-producing adenoma has been frequently shown to cause the most common form of adrenocorticotropic hormone-independent Cushing syndrome.
SUMMARY: Somatic PRKACA mutations have been found in up to 50% of patients with adrenal adenomas. Germline PRKACA amplification was also seen in bilateral adrenal hyperplasias. PRKACA activation was associated with higher cortisol levels, smaller tumor size and overt Cushing syndrome. This breakthrough is expected to improve our understanding of how PKA defects lead to Cushing syndrome and may spearhead the development of new, molecularly designed therapies.

Sousa SF, Gomez RS, Diniz MG, et al.
Defects of the Carney complex gene (PRKAR1A) in odontogenic tumors.
Endocr Relat Cancer. 2015; 22(3):399-408 [PubMed] Free Access to Full Article Related Publications
The surgical treatment of some odontogenic tumors often leads to tooth and maxillary bone loss as well as to facial deformity. Therefore, the identification of genes involved in the pathogenesis of odontogenic tumors may result in alternative molecular therapies. The PRKAR1A gene displays a loss of protein expression as well as somatic mutations in odontogenic myxomas, an odontogenic ectomesenchymal neoplasm. We used a combination of quantitative RT-PCR (qRT-PCR), immunohistochemistry, loss of heterozygosity (LOH) analysis, and direct sequencing of all PRKAR1A exons to assess if this gene is altered in mixed odontogenic tumors. Thirteen tumors were included in the study: six ameloblastic fibromas, four ameloblastic fibro-odontomas, one ameloblastic fibrodentinoma, and two ameloblastic fibrosarcomas. The epithelial components of the tumors were separated from the mesenchymal by laser microdissection in most of the cases. We also searched for odontogenic pathology in Prkar1a(+) (/) (-) mice. PRKAR1A mRNA/protein expression was decreased in the benign mixed odontogenic tumors in association with LOH at markers around the PRKAR1A gene. We also detected a missense and two synonymous mutations along with two 5'-UTR and four intronic mutations in mixed odontogenic tumors. Prkar1a(+) (/) (-) mice did not show evidence of odontogenic tumor formation, which indicates that additional genes may be involved in the pathogenesis of such tumors, at least in rodents. We conclude that the PRKAR1A gene and its locus are altered in mixed odontogenic tumors. PRKAR1A expression is decreased in a subset of tumors but not in all, and Prkar1a(+) (/) (-) mice do not show abnormalities, which indicates that additional genes play a role in this tumor's pathogenesis.

Szarek E, Ball ER, Imperiale A, et al.
Carney triad, SDH-deficient tumors, and Sdhb+/- mice share abnormal mitochondria.
Endocr Relat Cancer. 2015; 22(3):345-52 [PubMed] Free Access to Full Article Related Publications
Carney triad (CTr) describes the association of paragangliomas (PGL), pulmonary chondromas, and gastrointestinal (GI) stromal tumors (GISTs) with a variety of other lesions, including pheochromocytomas and adrenocortical tumors. The gene(s) that cause CTr remain(s) unknown. PGL and GISTs may be caused by loss-of-function mutations in succinate dehydrogenase (SDH) (a condition known as Carney-Stratakis syndrome (CSS)). Mitochondrial structure and function are abnormal in tissues that carry SDH defects, but they have not been studied in CTr. For the present study, we examined mitochondrial structure in human tumors and GI tissue (GIT) of mice with SDH deficiency. Tissues from 16 CTr tumors (n=12), those with isolated GIST (n=1), and those with CSS caused by SDHC (n=1) and SDHD (n=2) mutations were studied by electron microscopy (EM). Samples of GIT from mice with a heterozygous deletion in Sdhb (Sdhb(+) (/-), n=4) were also studied by EM. CTr patients presented with mostly epithelioid GISTs that were characterized by plump cells containing a centrally located, round nucleus and prominent nucleoli; these changes were almost identical to those seen in the GISTs of patients with SDH. In tumor cells from patients, regardless of diagnosis or tumor type, cytoplasm contained an increased number of mitochondria with a 'hypoxic' phenotype: mitochondria were devoid of cristae, exhibited structural abnormalities, and were of variable size. Occasionally, mitochondria were small and round; rarely, they were thin and elongated with tubular cristae. Many mitochondria exhibited amorphous fluffy material with membranous whorls or cystic structures. A similar mitochondrial hypoxic phenotype was seen in Sdhb(+) (/-) mice. We concluded that tissues from SDH-deficient tumors, those from mouse GIT, and those from CTr tumors shared identical abnormalities in mitochondrial structure and other features. Thus, the still-elusive CTr defect(s) is(are) likely to affect mitochondrial function, just like germline SDH-deficiency does.

Murnyák B, Szepesi R, Hortobágyi T
[Molecular genetics of familial tumour syndromes of the central nervous system].
Orv Hetil. 2015; 156(5):171-7 [PubMed] Related Publications
Although most of the central nervous system tumours are sporadic, rarely they are associated with familial tumour syndromes. These disorders usually present with an autosomal dominant inheritance and neoplasia develops at younger age than in sporadic cases. Most of these tumours are bilateral, multiplex or multifocal. The causative mutations occur in genes involved in cell cycle regulation, cell growth, differentiation and DNA repair. Studying these hereditary cancer predisposition syndromes associated with nervous system tumours can facilitate the deeper understanding of the molecular background of sporadic tumours and the development of novel therapeutic agents. This review is an update on hereditary tumour syndromes with nervous system involvement with emphasis on molecular genetic characteristics and their clinical implications.

Schernthaner-Reiter MH, Trivellin G, Stratakis CA
MEN1, MEN4, and Carney Complex: Pathology and Molecular Genetics.
Neuroendocrinology. 2016; 103(1):18-31 [PubMed] Free Access to Full Article Related Publications
Pituitary adenomas are a common feature of a subset of endocrine neoplasia syndromes, which have otherwise highly variable disease manifestations. We provide here a review of the clinical features and human molecular genetics of multiple endocrine neoplasia (MEN) type 1 and 4 (MEN1 and MEN4, respectively) and Carney complex (CNC). MEN1, MEN4, and CNC are hereditary autosomal dominant syndromes that can present with pituitary adenomas. MEN1 is caused by inactivating mutations in the MEN1 gene, whose product menin is involved in multiple intracellular pathways contributing to transcriptional control and cell proliferation. MEN1 clinical features include primary hyperparathyroidism, pancreatic neuroendocrine tumours and prolactinomas as well as other pituitary adenomas. A subset of patients with pituitary adenomas and other MEN1 features have mutations in the CDKN1B gene; their disease has been called MEN4. Inactivating mutations in the type 1α regulatory subunit of protein kinase A (PKA; the PRKAR1A gene), that lead to dysregulation and activation of the PKA pathway, are the main genetic cause of CNC, which is clinically characterised by primary pigmented nodular adrenocortical disease, spotty skin pigmentation (lentigines), cardiac and other myxomas and acromegaly due to somatotropinomas or somatotrope hyperplasia.

Aguiar de Sousa D, Gouveia AI, Wessling A, et al.
Sporadic Carney complex without PRKAR1A mutation in a young patient with ischemic stroke.
J Stroke Cerebrovasc Dis. 2015; 24(3):e79-81 [PubMed] Related Publications
We describe a 29-year-old male, with a previous history of testicular tumor, who presented with a posterior circulation ischemic stroke associated to an atrial myxoma. Dermatologic observation disclosed spotty skin and mucosal pigmentation (lentigines), and a cutaneous myxoma was histopathologically confirmed. Although there was no family history of any of the Carney complex (CNC) features and no mutations in the PRKAR1A gene were found, these findings lead to the diagnosis of CNC. We emphasize the importance of recognizing this entity in young patients with stroke.

Fukuoka H, Takahashi Y
The role of genetic and epigenetic changes in pituitary tumorigenesis.
Neurol Med Chir (Tokyo). 2014; 54(12):943-57 [PubMed] Free Access to Full Article Related Publications
Pituitary adenomas are one of the most common intracranial tumors. Despite their benign nature, dysregulation of hormone secretion causes systemic metabolic deterioration, resulting in high mortality and an impaired quality of life. Tumorigenic pathogenesis of pituitary adenomas is mainly investigated by performing genetic analyses of somatic mutations in the tumor or germline mutations in patients. Genetically modified mouse models, which develop pituitary adenomas, are also used. Genetic analysis in rare familial pituitary adenomas, including multiple endocrine neoplasia type 1 and type 4, Carney complex, familial isolated pituitary adenomas, and succinate dehydrogenases (SDHs)-mediated paraganglioma syndrome, revealed several causal germline mutations and sporadic somatic mutations in these genes. The analysis of genetically modified mouse models exhibiting pituitary adenomas has revealed the underlying mechanisms, where cell cycle regulatory molecules, tumor suppressors, and growth factor signaling are involved in pituitary tumorigenesis. Furthermore, accumulating evidence suggests that epigenetic changes, including deoxyribonucleic acid (DNA) methylation, histone modification, micro ribonucleic acids (RNAs), and long noncoding RNAs play a pivotal role. The elucidation of precise mechanisms of pituitary tumorigenesis can contribute to the development of novel targeted therapy for pituitary adenomas.

Duan K, Gomez Hernandez K, Mete O
Clinicopathological correlates of adrenal Cushing's syndrome.
J Clin Pathol. 2015; 68(3):175-86 [PubMed] Related Publications
Endogenous Cushing's syndrome is a rare endocrine disorder that incurs significant cardiovascular morbidity and mortality, due to glucocorticoid excess. It comprises adrenal (20%) and non-adrenal (80%) aetiologies. While the majority of cases are attributed to pituitary or ectopic corticotropin (ACTH) overproduction, primary cortisol-producing adrenal cortical lesions are increasingly recognised in the pathophysiology of Cushing's syndrome. Our understanding of this disease has progressed substantially over the past decade. Recently, important mechanisms underlying the pathogenesis of adrenal hypercortisolism have been elucidated with the discovery of mutations in cyclic AMP signalling (PRKACA, PRKAR1A, GNAS, PDE11A, PDE8B), armadillo repeat containing 5 gene (ARMC5) a putative tumour suppressor gene, aberrant G-protein-coupled receptors, and intra-adrenal secretion of ACTH. Accurate subtyping of Cushing's syndrome is crucial for treatment decision-making and requires a complete integration of clinical, biochemical, imaging and pathology findings. Pathological correlates in the adrenal glands include hyperplasia, adenoma and carcinoma. While the most common presentation is diffuse adrenocortical hyperplasia secondary to excess ACTH production, this entity is usually treated with pituitary or ectopic tumour resection. Therefore, when confronted with adrenalectomy specimens in the setting of Cushing's syndrome, surgical pathologists are most commonly exposed to adrenocortical adenomas, carcinomas and primary macronodular or micronodular hyperplasia. This review provides an update on the rapidly evolving knowledge of adrenal Cushing's syndrome and discusses the clinicopathological correlations of this important disease.

Ferrero S, Vaira V, Del Gobbo A, et al.
Different expression of protein kinase A (PKA) regulatory subunits in normal and neoplastic thyroid tissues.
Histol Histopathol. 2015; 30(4):473-8 [PubMed] Related Publications
The four regulatory subunits (R1A, R1B, R2A, R2B) of protein kinase A (PKA) are differentially expressed in several cancer cell lines and exert distinct roles in both cell growth and cell differentiation control. Mutations of the PRKAR1A gene have been found in patients with Carney complex and in a minority of sporadic anaplastic thyroid carcinomas. The aim of the study was to retrospectively evaluate the expression of different PKA regulatory subunits in benign and non benign human thyroid tumours and to correlate their expression with clinical phenotype. Immunohistochemistry demonstrated a significant increase in PRKAR2B expression in both differentiated and undifferentiated (anaplastic) thyroid tumors in comparison with normal thyroid tissues. Conversely, a significant increase in PRKAR1A expression was only demonstrated in undifferentiated thyroid carcinomas in comparison with normal thyroid tissue and differentiated thyroid tumors. In thyroid cancers without lymph nodal metastases PRKAR1A expression was higher in tumours of more than 2 cm in size (T2 and T3) compared to smaller ones (T1). In conclusion, our data shows that an increased PRKAR1A expression is associated with aggressive and undifferentiated thyroid tumors.

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