Pancreatic ductal and acinar cell neoplasms in Carney complex: a possible new association.

CONTEXT: Carney complex (CNC) is a rare disease inherited as an autosomal dominant trait, associated with various tumors, and caused most frequently by inactivation of the PRKAR1A gene. OBJECTIVES: In our recent investigation of a large cohort of CNC patients, we identified several cases of pancreatic neoplasms. This possible association and PRKAR1A's possible involvement in pancreatic tumor have not been reported previously. PATIENTS AND METHODS: Nine patients (2.5%) with CNC and pancreatic neoplasms in an international cohort of 354 CNC patients were identified; we studied six of them. Immunohistochemistry and PRKAR1A sequencing were obtained. RESULTS: Three men and three women with a mean age of 49 yr (range 34-75 yr) had acinar cell carcinoma (n = 2), adenocarcinoma (n = 1), and intraductal pancreatic mucinous neoplasm (n = 3). Five patients had a germline PRKAR1A mutation, including two patients with acinar cell carcinoma, for whom mutations were found in a hemizygous state in the tumor, suggesting loss of heterozygosity. PRKAR1A expression was not detected in five of the six pancreatic neoplasms from CNC patients, whereas the protein was amply expressed on other sporadic pancreatic tumors and normal tissue. CONCLUSION: An unexpectedly high prevalence of rare pancreatic tumors was found among CNC patients. Immunohistochemistry and loss-of-heterozygosity studies suggest that PRKAR1A could function as a tumor suppressor gene in pancreatic tissue, at least in the context of CNC. Clinicians taking care of CNC patients should be aware of the possible association of CNC with a potentially aggressive pancreatic neoplasm.

Comparative validation of the growth hormone-releasing hormone and arginine test for the diagnosis of adult growth hormone deficiency using a growth hormone assay conforming to recent international recommendations.

CONTEXT: The GHRH plus arginine (GHRH+Arg) test is a promising alternative to the insulin tolerance test (ITT) for diagnosis of adult GH deficiency (AGHD). OBJECTIVES: The objectives of the study were to validate the GHRH+Arg test for diagnosis of AGHD, using the ITT as comparator and a GH assay calibrated according to recent international recommendations, and to study the repeatability and tolerance of both tests. DESIGN: This was a multicenter, randomized, open-label, phase III study. SETTING: The study was conducted at 10 French university hospitals. SUBJECTS: Sixty-nine subjects (38 and 15 with high and low probability of GH deficiency, respectively, and 16 healthy controls) were randomized: 35 to the GHRH+Arg-GHRH+Arg-ITT test sequence and 34 to the ITT-ITT-GHRH+Arg test sequence. INTERVENTIONS: Each subject underwent three tests of GH secretion separated by 24 h or more. MAIN OUTCOME MEASURES: The primary variable used for response assessments was serum peak GH response. Test results were compared with the final AGHD diagnosis. RESULTS: Peak GH responses in the two tests were strongly correlated. A cutoff value of 7.89 microg/liter for GHRH+Arg corresponding to 3 microg/liter for ITT was calculated. The cutoff value leading to 95% specificity with the GHRH+Arg test was measured at about 3.67 microg/liter (sensitivity 79.0%). Intermethod agreement and repeatability were high. Both tests were well tolerated. A preference for the GHRH+Arg test was expressed by 74% of subjects. CONCLUSIONS: The GHRH+Arg test demonstrated good accuracy and repeatability, was at least as sensitive as the ITT, and was associated with better subject acceptability. The GHRH+Arg test represents a good alternative to the ITT for the diagnosis of AGHD.

Molecular and functional analysis of PRKAR1A and its locus (17q22-24) in sporadic adrenocortical tumors: 17q losses, somatic mutations, and protein kinase A expression and activity.

Germ-line protein kinase A (PKA) regulatory-subunit type-Ialpha (RIalpha; PRKAR1A)-inactivating mutations and loss-of-heterozygosity (LOH) of its 17q22-24 locus have been found in Cushing syndrome (CS) caused by primary pigmented nodular adrenocortical disease (PPNAD). We examined whether somatic 17q22-24, PRKAR1A, or PKA changes are present in 44 sporadic adrenocortical tumors (29 adenomas and 15 cancers); 26 of these tumors were responsible for CS. A probe containing the PRKAR1A gene-mapped by fluorescent in situ hybridization to 17q22-24-and corresponding microsatellite markers were used to study allelic losses; PRKAR1A was sequenced in all samples. 17q22-24 losses were seen in 23 and 53% of adenomas and cancers, respectively. In three tumors, somatic, PRKAR1A-inactivating mutations were identified: (a) a nonsense mutation in exon 6 (A751G); (b) a splicing mutation (9IVS-1G/A); and (c) a transition (1050T>C) followed by a 22-bp deletion, also in exon 9; all predicted premature RIalpha protein terminations. Quantitative message and protein studies showed RIalpha down-regulation in tumors with genetic changes; their cortisol secretion pattern was similar to that of PPNAD, and they had higher PKA activity by enzymatic studies. We conclude that somatic allelic losses of the 17q22-24 region, PRKAR1A-inactivating mutations or down-regulation, and corresponding PKA activity changes are present in at least some sporadic adrenocortical tumors, especially those with a PPNAD-like clinical presentation of CS.

Molecular analysis of the cyclic AMP-dependent protein kinase A (PKA) regulatory subunit 1A (PRKAR1A) gene in patients with Carney complex and primary pigmented nodular adrenocortical disease (PPNAD) reveals novel mutations and clues for pathophysiology: augmented PKA signaling is associated with adrenal tumorigenesis in PPNAD.

We studied 11 new kindreds with primary pigmented nodular adrenocortical disease (PPNAD) or Carney complex (CNC) and found that 82% of the kindreds had PRKAR1A gene defects (including seven novel inactivating mutations), most of which led to nonsense mRNA and, thus, were not expressed in patients' cells. However, a previously undescribed base substitution in intron 6 (exon 6 IVS +1G-->T) led to exon 6 skipping and an expressed shorter PRKAR1A protein. The mutant protein was present in patients' leukocytes and tumors, and in vitro studies indicated that the mutant PRKAR1A activated cAMP-dependent protein kinase A (PKA) signaling at the nuclear level. This is the first demonstration of an inactivating PRKAR1A mutation being expressed at the protein level and leading to stimulation of the PKA pathway in CNC patients. Along with the lack of allelic loss at the PRKAR1A locus in most of the tumors from this kindred, these data suggest that alteration of PRKAR1A function (not only its complete loss) is sufficient for augmenting PKA activity leading to tumorigenesis in tissues affected by CNC.