Objective: Somatotropinomae are classified as densely and sparsely granulated adenomae, which typically exhibit a perinuclear pattern (PP) and a dot pattern (DP) in cytokeratin (CK) immunostaining respectively. Some exhibit a mixed pattern (MP). We studied the relationship between these somatotropinoma subtypes and their clinico-pathological features. Methods: The study population consisted of 141 Japanese acromegalic patients. We evaluated their clinical presentation and their response to provocation tests with TRH and LHRH and to suppression (octreotide) test. Tumour tissues were subjected to immunostaining for CAM-5.2, MIB-1, CD34, E-cadherin (CDH1) and p53 (TP53). In 43 cases (30 non-DP and 13 DP), we analysed gsp mutations (constitutively activating mutations of the G s a protein that is encoded by GNAS gene). Results: The 141 adenomae were categorised into three subtypes based on their CK staining patterns; 30 (21.3%) exhibited DP, 83 (58.9%) exhibited PP, and 28 (19.9%) exhibited MP. Compared with the other subtypes, DP adenomae were significantly larger, and their E-cadherin expression and response to TRH, LHRH and octreotide challenge were lower. The postoperative cure rate tended to be lower in DP adenomae. gsp mutations were detected in 25 of 43 cases examined (58.1%); 20 of the 30 non-DP (66.7%) and 5 of the 13 DP tumours (38.5%) were affected by the mutation. Conclusion: DP somatotropinomae exhibit characteristic features. Compared with the non-DP subtypes, DP adenomae manifested a larger tumour size, a lower incidence of abnormal responses to TRH and LHRH challenge, a poor response to octreotide test and a lower expression of E-cadherin. gsp mutation was not exclusive for non-DP somatotropinomae.

Neurofibromin is a neurofibromatosis type 1 (NF1) tumor suppressor gene product with a domain that acts as a GTPase-activating protein and functions, in part, as a negative regulator of Ras. Loss of neurofibromin expression in NF1 patients is associated with elevated Ras activity and increased cell proliferation, predisposing to a variety of tumors of the peripheral and central nervous systems. We show here, using the small interfering RNA (siRNA) technique, that neurofibromin dynamically regulates actin cytoskeletal reorganization, followed by enhanced cell motility and gross cell aggregation in Matrigel matrix. NF1 siRNA induces characteristic morphological changes, such as excessive actin stress fiber formation, with elevated negative phosphorylation levels of cofilin, which regulates actin cytoskeletal reorganization by depolymerizing and severing actin filaments. We found that the elevated phosphorylation of cofilin in neurofibromin-depleted cells is promoted by activation of a Rho-ROCK-LIMK2 pathway, which requires Ras activation but is not transduced through three major Ras-mediated downstream pathways via Raf, phosphatidylinositol 3-kinase, and RalGEF. In addition, the exogenous expression of the NF1-GTPase-activating protein-related domain suppressed the NF1 siRNA-induced phenotypes. Neurofibromin was demonstrated to play a significant role in the machinery regulating cell proliferation and in actin cytoskeletal reorganization, which affects cell motility and adhesion. These findings may explain, in part, the mechanism of multiple neurofibroma formation in NF1 patients.Neurofibromatosis type 1 (NF1), 2 also called von Recklinghausen disease, is autosomal dominant and one of the most common inherited disorders, affecting 1 in 3500 individuals (1). The phenotype of NF1 is highly variable, with several organ systems being affected, including bones, skin, irises, and central and peripheral nervous systems. The disease commonly manifests with "café au lait" macules in the skin, iris Lisch nodules, and learning disability (2, 3). The hallmark of NF1 is benign tumors that develop in the peripheral nervous system accompanied by an increased risk of malignancies.The NF1 gene lies on chromosome 17q11.2 and encodes a large 2818-amino acid protein, termed neurofibromin. Sequence analysis of neurofibromin revealed that a region centered around the 360 amino acids encoded by the NF1 gene shows significant homology to the known catalytic domains of mammalian Ras GTPase-activating protein (p120GAP), which interacts with Ras and promotes hydrolysis of Rasbound GTP (active form) to GDP (inactive form), resulting in inactivation of the Ras protein. Accordingly, loss and/or mutations of neurofibromin elevate Ras activity and are followed by activation of various Ras effectors. Ras activation has been considered to be the causative event for tumor formation and other clinical manifestations in NF1 patients (2, 3).Recent studies have suggested that neurofibromin has additional functions besides regulating cell proliferation ...

A lthough malignant tumors metastasizing into the pituitary fossa are not infrequent events in autopsy series, 6,10,17,18 pituitary metastasis (PM) is rarely diagnosed ante mortem. 3,14,18 According to the Brain Tumor Registry of Japan, only 0.4% of intracranial metastatic tumors are located in the pituitary gland. 5 These tumors account for only 1% of surgically treated pituitary tumors. 8,16,31 Recently, as the number of patients diagnosed with cancer has increased and their survival time has been extended, PMs have been diagnosed more frequently than before. 16,20,24 Many authors have reported their own experiences or their institutional series on PMs. 3,11,13,14,20,26,31 There are also reviews involving large numbers of reported cas- results Between 1995 and 2010, 201 patients with PMs were treated by the participating physicians. The diagnosis of PM was histologically verified in 69 patients (34.3%). In the other 132 patients (65.7%), the PM was diagnosed by their physicians based on neuroimaging findings and clinical courses. The most frequent primary tumor was lung (36.8%), followed by breast (22.9%) and kidney (7.0%) cancer. The average interval between diagnosis of primary cancer and detection of PM was 2.8 ± 3.9 (SD) years. Major symptoms at diagnosis were visual disturbance in 30.3%, diabetes insipidus in 27.4%, fatigue in 25.4%, headache in 20.4%, and double vision in 17.4%. Major neuroimaging features were mass lesion in the pituitary stalk (63.3%), constriction of tumor at the diaphragmatic hiatus (44.7%), hypothalamic mass lesion (17.4%), and hyperintensity in the optic tract (11.4%). Surgical treatment was performed in 26.9% of patients, and 74.6% had radiation therapy; 80.0% of patients who underwent radiotherapy had stereotactic radiotherapy. The median survival time was 12.9 months in total. Contributing factors for good prognosis calculated by Cox proportional hazard analysis were younger age, late metastasis to the pituitary gland, smaller PM size, and radiation therapy. The Kaplan-Meier survival was significantly better in patients with breast cancer and renal cell cancer than in those with lung cancer. coNclusioNs At the time of this writing, approximately 60% (120/201) of PMs had been treated by stereotactic radiation therapy in Japan. The median survival time was much longer than that reported in past series. To confirm the changes of clinical features and medical practice, a prospective and population-based survey is mandatory.

Neurofibromin, the neurofibromatosis type 1 (NF1) gene product, contains a central domain homologous to a family of proteins known as Ras-GTPase-activating proteins (Ras-GAPs), which function as negative regulators of Ras. The loss of neurofibromin function has been thought to be implicated in the abnormal regulation of Ras in NF1-related pathogenesis. In this study, we found a novel role of neurofibromin in neuronal differentiation in conjunction with the regulation of Ras activity via its GAP-related domain (GRD) in neuronal cells. In PC12 cells, time-dependent increases in the GAP activity of cellular neurofibromin (NF1-GAP) were detected after NGF stimulation, which were correlated with the down-regulation of Ras activity during neurite elongation. Interestingly, the NF1-GAP increase was due to the induction of alternative splicing of NF1-GRD type I triggered by the NGF-induced Ras activation. Dominantnegative (DN) forms of NF1-GRD type I significantly inhibited the neurite extension of PC12 cells via regulation of the Ras state. NF1-GRD-DN also reduced axonal and dendritic branching/extension of rat embryonic hippocampal neurons. These results demonstrate that the mutual regulation of Ras and NF1-GAP is essential for normal neuronal differentiation and that abnormal regulation in neuronal cells may be implicated in NF1-related learning and memory disturbance. Neurofibromatosis type 1 (NF1)1 is one of the most common autosomal dominantly inherited disorders, with an incidence of about 1 in 3500 individuals (1). The NF1 hallmark is the development of benign tumors of the peripheral nervous system and the increased risk of developing malignancies. The NF1 phenotype is highly variable; it affects several organ systems, including bones, skin, irises, and central nervous system manifested as gliomas and learning disabilities. The NF1 gene lies on chromosome 17q11.2 and encodes neurofibromin, a large 2818-amino acid protein (2). Since the majority of NF1 gene mutations frequently found in NF1 patients prevent intact neurofibromin expression, functional disruption of neurofibromin is potentially relevant to the expression of some or all of the multiple abnormalities that occur in NF1 patients (3).A region centered around the 360 amino acids encoded by the NF1 gene shows significant homology to the known catalytic domains of mammalian Ras GTPase-activating protein (p120GAP) and is also similar to yeast IRA1/2 proteins, which interact with Ras and mediate hydrolysis of Ras-bound GTP to GDP, resulting in Ras protein inactivation. The GAP-related domain of the NF1 gene product (NF1-GRD) also stimulates Ras GTPase and consequently inactivates Ras protein (4, 5).Two different isoforms, type I and type II, which are formed by alternative splicing, have been identified in the NF1-GRD region. Type II contains an additional 63-bp insertion (exon 23a) that encodes 21 amino acids in the center of NF1-GRD type I (6). The specific expression patterns of the two isoforms have been studied in several organs and cells (7,8) and pro...