• Journal of Korean Neurosurgical Society
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• v.57 no.6
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• pp.408-414
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• 2015

Moyamoya-like vasculopathy develops in association with various systemic diseases and conditions, which is termed moyamoya syndrome. Relatively common diseases and conditions are related to moyamoya syndrome, including neurofibromatosis type 1, Down syndrome, thyroid disease, and cranial irradiation. Moyamoya syndrome shares phenotypical characteristics with idiopathic moyamoya disease. However, they differ in other details, including clinical presentations, natural history, and treatment considerations. The study of moyamoya syndrome can provide clinicians and researchers with valuable knowledge and insight. Although it is infrequently encountered in clinical practice, moyamoya-like vasculopathy can severely complicate outcomes for patients with various underlying diseases when the clinician fails to expect or diagnose moyamoya syndrome development. Furthermore, moyamoya syndrome could be used as a doorway to more enigmatic moyamoya disease in research. More comprehensive survey and investigation are required to uncover the secrets of all the moyamoya-like phenomena.

• Journal of Genetic Medicine
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• v.14 no.2
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• pp.56-61
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• 2017

Purpose: Neurofibromatosis type 2 (NF2) is characterized by multiple tumors, including vestibular schwannoma (VS) and others affecting cranial and peripheral nerves. NF2 is caused by mutation of the NF2 gene. The mutation spectrum of NF2 has not been characterized in Korean patients. In the current study, the clinical and genetic characteristics of Korean NF2 patients were analyzed. Materials and Methods: Twenty-five unrelated Korean families were enrolled according to the Manchester criteria. Genetic analysis was performed by direct sequencing and multiplex ligation-dependent probe amplification methods using genomic DNA from peripheral lymphocytes or tumor tissues. Results: All patients had bilateral/unilateral VS and/or other cranial and peripheral nerve tumors. Two patients were familial cases and the other 24 patients were sporadic. Germline NF2 mutations were detected in peripheral lymphocytes from both familial cases, but only in 26.1% of the 23 sporadic families. Somatic mutations were also found in tumor tissues from two of the sporadic families. These somatic mutations were not found in peripheral lymphocytes. A total of 10 different mutations including 2 novel mutations were found in 40.0% of studied families. Five mutations (50.0%) were located in exon 6 of NF2, the FERM domain coding region. Conclusion: Family history was an important factor in identifying germline NF2 mutations. Further study is required to investigate whether exon 6 is a mutation hotspot in Korean NF2 patients and its correlation to phenotypic severity.

• BMB Reports
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• v.49 no.7
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• pp.357-358
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• 2016

Merlin, encoded by the NF2 gene, is a tumor suppressor that exerts its function via inhibiting mitogenic receptors at the plasma membrane. Although multiple mutations in Merlin have been identified in Neurofibromatosis type II (NF2) disease, its molecular mechanism is not fully understood. Here, we show that Merlin interacts with LRP6 and inhibits LRP6 phosphorylation, a critical step for the initiation of Wnt signaling. We found that treatment of Wnt3a caused phosphorylation of Merlin by PAK1, leading to detachment of Merlin from LRP6 and allowing the initiation of Wnt/β-catenin signaling. A higher level of β-catenin was found in tissues from NF2 patients. Enhanced proliferation and migration caused by knockdown of Merlin in glioblastoma cells were inhibited by suppression of β-catenin. Conclusively, these results suggest that sustained Wnt/β-catenin signaling activity induced by abrogation of Merlin-mediated inhibition of LRP6 phosphorylation might be a cause of NF2 disease.

• The Microorganisms and Industry
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• v.19 no.4
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• pp.32-35
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• 1993

ras는 활성화 형태인 GTP bound form과 비활성화 형태인 GDP bound form의 두 형태로 존재하며 두 형태를 매개하는 regulatory protein들에 의해 그 activity가 조절된다. 또한 ras는 GTP와 GDP에 강한 친화성이 있으며 세포내에는 GTP보다 GDP가 더 많이 있어서 평소에는 ras가 GDP와 결합하고 있다가 활성화될때만 GTP와 결합하는 것으로 추정된다. GDP bound ras는 guanine nucloetide exchange protein(GEP)에 의해 활성화된 GTP bound form으로 전환되며 ras의 기능이 발휘된 후에는 GTPase activating protein(GAP)에 의해 비활성화된다. Yeast의 경우 IRA1과 2의 product가 GAP의 역할을 하는 것으로 알려져 있고 CDC25 gene의 product가 GEP의 기능을 담당하는 것으로 알려져 있다. NF1 gene은 Von Recklinghausen Neurofibromatosis Type I 질병을 가진 환자에게서 발견되었는데 부분적으로 sequencing한 결과에 따르면 yeast의 IRA1/2, mammalian GAP gene product와 protein homology가 높은 것으로 나타났다. Yeast의 경우 IRA1/2 gene의 손실이나 mammalian ras gene의 transformation으로 인한 heat shock sensitivity가 NF1 gene(2,3) 혹은 GAP(4)의 expression으로 suppression된 것으로 보아 NF1이 GAP protein으로서 ras를 불활성화 시킨다는 것이 판명되었다. 결론적으로 ras의 활성은 GTP bound 혹은 GDP bound의 양쪽형태를 이동하면서 조절되는데 이 기능은 GAP과 GEP 또는 그의 유사 protein들에 의해 수행되며 이러한 regulatory protein들은 growth factor, cytokine 그리고 protein kinase 같은 signal에 의해 활성화된다고 생각된다. 본 총설에서는 ras protein의 여러가지 성질보다는 ras의 modification과 관련하여 항암제로 사용할 수 있는 ras에 specific한 약품개발의 가능성과 현재 알려진 ras의 inhibitor를 중심으로 논하고자 한다.

• Korean Journal of Head & Neck Oncology
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• v.29 no.2
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• pp.54-57
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• 2013

Malignant triton tumor(MTT) is a rare type of malignant peripheral nerve sheath tumor(MPNST) with focal rhabdomyoblastic differentiation. MTT constitutes about 5% of all MPNSTs and described the first case of a MTT in a patient with Von Recklinghausen disease by Masson in 1932. MTT is commonly seen in the head, neck, extremities and trunk. It can occur in sporadic form or over a setting of neurofibromatosis-1(NF-1). The diagnosis can be confirmed based on morphologic grounds supported by an immunostain such as S-100 protein. Desmin, myo-D1 and myogenin are immunostains positive for rhabdomyoblasts. MTT has an aggressive biological behavior so prognosis of this rare and highly malignant tumor is poor and optimal treatment remains unclear. But modern treatment consisted of radical excision and postoperative radiotherapy has improved the prognosis of such cases.

• Journal of Chest Surgery
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• v.49 no.2
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• pp.130-133
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• 2016

The rupture of an internal mammary artery (IMA) aneurysm in a patient with type 1 neurofibromatosis (NF-1) is a rare but life-threatening complication requiring emergency management. A 50-year-old man with NF-1 was transferred to the emergency department of Kyungpook National University Hospital, where an IMA aneurysmal rupture and hemothorax were diagnosed and drained. The IMA aneurysmal rupture and hemothorax were successfully repaired by staged management combining endovascular treatment and subsequent video-assisted thoracoscopic surgery (VATS). The patient required cardiopulmonary cerebral resuscitation, the staged management of coil embolization, and a subsequent VATS procedure. This staged approach may be an effective therapeutic strategy in cases of IMA aneurysmal rupture.

• Journal of Yeungnam Medical Science
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• v.33 no.1
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• pp.44-47
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• 2016

Primary dissection of the renal artery is rare. Spontaneous renal artery dissection can be associated with diseases such as medial degeneration, neurofibromatosis, syphilitic arteritis, tuberculosis, polyarteritis nodosa, Marfan syndrome, fibromuscular dysplasia, or Ehlers-Danlos syndrome (EDS). Among these causes, EDS related renal artery dissection is very rare worldwide and has not been previously reported in Korea. EDS are a group of heritable connective tissue disorders characterized by fragility of the skin and hypermobility of the joints. We describe the case history of a young man who presented with left side flank pain, hypermobility of the hand joints and showed left renal artery dissection on computed tomography and angiography that turned out to be the first complication of vascular type EDS.

• Archives of Reconstructive Microsurgery
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• v.22 no.2
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• pp.78-81
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• 2013

Neurofibroma may present as a solitary lesion or as multiple lesions. Although there is no site of predilection for solitary lesions, occurrence on the hand is rare. Plexiform neurofibroma can develop in isolation or more commonly as a part of neurofibromatosis type 1. In those that apper in isolation, trauma has been suggested as a precipitating factor. A 68-year-old male farmer had experienced repetitive prior episodes of trauma in the involved finger. He presented with a painless mass on the dorsal aspect of the fifth finger. Physical examination showed a protruding mass measuring approximately $15{\times}20mm$ which was not tenderness to palpation and any skin changes or pigmentation. Ultrasonography showed a cystic mass on the dorsal aspect of the middle phalanx. Microsurgical dissection was applied in order to seperated the lesion from the ulnar side of the dorsal branch of the digital nerve. Pathologic examination of the specimens revealed neurofibroma. At three-month follow-up, motor and sensory function were intact, and range of motion was fully recovered. Traumatic solitary neurofibroma is a rare tumor of the hand, especially in the finger. Hand surgeons should be aware of the diagnostic possibilities of this tumor based on examination, history taking and imaging studies.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.886-889
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• 2011

Purpose: Malignant peripheral nerve sheath tumor without neurofibromatosis type 1 is very rare neoplasm. Development in the superficial soft tissue is exremely rare. Authors experienced one rare case of primary malignant peripheral nerve sheath tumor developed on abdomen. The clinical and histologic findings were described. Methods: An 83-year-old man visited hospital with an $11{\times}6.5{\times}4.5$ cm sized ulcerated and hemorrhagic mass on abdomen. The tumor was localized in abdominal skin and started growing 3 years ago. Results: Wide excision with safety margin of 2 cm and limberg flap was done. The postoperative biopsy revealed a malignant peripheral nerve sheath tumor. There was no evidence of recurrence of tumor for 16 months. Conclusion: Malignant peripheral nerve sheath tumor is an aggressive malignant tumor. An abrupt enlargement of size, ulceration and bleeding are suggestive of malignant chnages of the tumor. We recommand early wide excision with enough safety margin as treatment of malignant peripheral nerve sheath tumor.

• Journal of Life Science
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• v.28 no.9
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• pp.1100-1117
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• 2018

The Ras superfamily of small G-proteins acts as a molecular switch on the intracellular signaling pathway. Upon ligand stimulation, inactive GTPases (Ras-GDP) are activated (Ras-GTP) using guanine nucleotide exchange factor (GEF) and transmit signals to their downstream effectors. Following signal transmission, active Ras-GTP become inactive Ras-GDP and cease signaling. However, the intrinsic GTPase activity of Ras proteins is weak, requiring Ras GTPase-activating protein (RasGAP) to efficiently convert RAS-GTP to Ras-GDP. Since deregulation of the Ras pathway is found in nearly 30% of all human cancers, it might be useful to clarify the structural and physiological roles of Ras GTPases. Recently, RasGAP has emerged as a new class of tumor-suppressor protein and a potential therapeutic target for cancer. Therefore, it is important to clarify the physiological roles of the individual GAPs in human diseases. The first RasGAP discovered was RASA1, also known as p120 RasGAP. RASA1 is widely expressed, independent of cell type and tissue distribution. Subsequently, neurofibromatosis type 1 (NF1) was discovered. The remaining GAPs are affiliated with the GAP1 and synaptic GAP (SynGAP) families. There are more than 170 Ras GTPases and 14 Ras GAP members in the human genome. This review focused on the current understanding of Ras GTPase and RasGAP in human diseases, including cancers.