Pituitary adenomas are common neoplasms of the anterior pituitary gland. Germ-line mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene cause pituitary adenoma predisposition (PAP), a recent discovery based on genetic studies in Northern Finland. In this population, a founder mutation explained a significant proportion of all acromegaly cases. Typically, PAP patients were of a young age at diagnosis but did not display a strong family history of pituitary adenomas. To evaluate the role of AIP in pituitary adenoma susceptibility in other populations and to gain insight into patient selection for molecular screening of the condition, we investigated the possible contribution of AIP mutations in pituitary tumorigenesis in patients from Europe and the United States. A total of 460 patients were investigated by AIP sequencing: young acromegaly patients, unselected acromegaly patients, unselected pituitary adenoma patients, and endocrine neoplasia-predisposition patients who were negative for MEN1 mutations. Nine AIP mutations were identified. Because many of the patients displayed no family history of pituitary adenomas, detection of the condition appears challenging. Feasibility of AIP immunohistochemistry (IHC) as a prescreening tool was tested in 50 adenomas: 12 AIP mutation-positive versus 38 mutation-negative pituitary tumors. AIP IHC staining levels proved to be a useful predictor of AIP status, with 75% sensitivity and 95% specificity for germ-line mutations. AIP contributes to PAP in all studied populations. AIP IHC, followed by genetic counseling and possible AIP mutation analysis in IHC-negative cases, a procedure similar to the diagnostics of the Lynch syndrome, appears feasible in identification of PAP.immunohistochemistry ͉ growth hormone/prolacting-secreting adenomas ͉ acromegaly

A deficit of exogenous arginine affects growth and viability of numerous cancer cells. Although arginine deprivation-based strategy is currently undergoing clinical trials, molecular mechanisms of tumor cells’ response to arginine deprivation are not yet elucidated. We have examined effects of arginine starvation on cell motility, adhesion and invasiveness as well as on actin cytoskeleton organization of human glioblastoma cells. We observed for the first time that arginine, but not lysine, starvation affected cell morphology, significantly inhibited their motility and invasiveness, and impaired adhesion. No effects on glia cells were observed. Also, arginine deprivation in glioblastoma evoked specific changes in actin assembly, decreased β-actin filament content, and affected its N-terminal arginylation. We suggest that alterations in organization of β-actin resulted from a decrease of its arginylation could be responsible for the observed effects of arginine deprivation on cell invasiveness and migration. Our data indicate that arginine deprivation-based treatment strategies could inhibit, at least transiently, the invasion process of highly malignant brain tumors and may have a potential for combination therapy to extend overall patient survival.Electronic supplementary materialThe online version of this article (doi:10.1007/s00726-014-1857-1) contains supplementary material, which is available to authorized users.

While mutations were absent in non-GH-secreting adenoma patients, germline AIP mutations can be found in children and adolescents with GH-secreting tumours, even in the absence of family history. The present study reports the AIP mutation analysis results on patients of a single ethnic origin. Clearly, further studies are needed to improve our knowledge on the role of AIP in paediatric pituitary adenomas.

Myosin VI (MVI) is the only known myosin walking towards minus end of actin filaments and is believed to play distinct role(s) than other myosins. We addressed a role of this unique motor in secretory PC12 cells, derived from rat adrenal medulla pheochromocytoma using cell lines with reduced MVI synthesis (produced by means of siRNA). Decrease of MVI expression caused severe changes in cell size and morphology, and profound defects in actin cytoskeleton organization and Golgi structure. Also, significant inhibition of cell migration as well as cell proliferation was observed. Flow cytometric analysis revealed that MVI-deficient cells were arrested in G0/G1 phase of the cell cycle but did not undergo increased senescence as compared with control cells. Also, neither polyploidy nor aneuploidy were detected. Surprisingly, no significant effect on noradrenaline secretion was observed. These data indicate that in PC12 cells MVI is involved in cell migration and proliferation but is not crucial for stimulation-dependent catecholamine release.