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S. Hasegawa
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P1.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 224)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.08-002 - Stat3 Is a Potential Target for Malignant Pleural Mesothelioma (MPM) Treatment (ID 1649)
09:30 - 09:30 | Author(s): S. Hasegawa
- Abstract
Background:
The prognosis of malignant pleural mesothelioma (MPM) is very poor; thus, a new drug treatment is necessary. Serum IL-6 is high in patients with MPM because of the activation of IL-6/Stat3 pathway. Thus, we investigated Stat3 as a potential target for the treatment of MPM.
Methods:
Cell viability was examined using the Cell Counting Kit-8 (CCK-8: WST-8 Dojindo). MPM cell lines (NCI-H28, NCI-H226, NCI-H2052, NCI-H2452, and MSTO-211H) were seeded onto 96-well plates. After treatment with Stattic, a Stat3 inhibitor, CCK-8 solution was added to each well and absorbance was measured using a microplate reader. Phosphorylated Stat3 levels (p-Stat3) were measured in cell lysates using the InstantOne ELISA assay (eBioscience). The expression of p-Stat3, E-cadherin, and vimentin was determined by western blot analysis. Translocated p-Stat3 was analyzed by confocal immunofluorescence microscopy. Cells were plated onto chamber slides containing medium. After the Stattic treatment, cells were fixed and cell membranes permeabilized. p-Stat3 antibody was added to chamber slides and incubated overnight at 4°C. Images were captured using a Zeiss LSM780 confocal microscopy system. Apotosis induced by Stat3 inhibitor was measured using the Caspase-GloR 3/7 assay (Promega). Cells were seeded onto 96-well plates. After the Stattic treatment, Caspase-GloR 3/7 reagent was added to each well, and the luminescence of each sample was measured in a plate-reading luminometer. For our in vivo study, H226 cells were subcutaneously injected into the flank region of nude mice. Mice were randomly assigned into two groups, with 5 mice in each group: vehicle control and Stattic (treated with10 mg/kg po 5 days per week).
Results:
Stattic inhibited viability of all MPM cell lines in a dose-dependent manner. IC50 values ranged from 3.3–106.0 μM. p-Stat3 levels decreased by 50% with 1 μM Stattic treatment in H226 cells. H226 cells were treated with 0.01 to 10 μM Stattic. Vimentin expression was stable; however, E-cadherin expression increased with 0.1, 1, and 10 μM Stattic treatment. In untreated H226 cells, p-Stat3 was observed in the cytoplasm and localized in the nucleus. In contrast, in Stattic-treated cells, decreased p-Stat3 was observed in the cytoplasm only, and it did not localize to the nucleus. Caspase 3/7 cleavage increased with Stattic treatment after 12 h and decreased after 48 h. In vivo mouse xenograft model, Stattic suppressed tumor growth (vehicle control vs.Stattic, P < 0.05).
Conclusion:
In this study, we have shown that Stattic inhibits proliferation of all MPM cell lines and suppresses tumor growth in a mouse model. In addition, we have demonstrated that Stattic inhibits Stat3 phosphorylation and blocks nuclear translocation. Furthermore, Stattic inhibits EMT. Thus, the STAT3 inhibitor is a promising candidate in MPM therapy.
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P3.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 226)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.08-006 - NF2 Mutations in Malignant Pleural Mesothelioma Synchronous with Acoustic Neuroma: Disease-Causing Mutation or Chance Effect? (ID 2562)
09:30 - 09:30 | Author(s): S. Hasegawa
- Abstract
Background:
Patients with neurofibromatosis type 2 (NF2) are predisposed to schwannomas and meningiomas. Somatic NF2 mutation has also been reported in patients with sporadic schwannomas and a variety of cancers. In particular, approximately 35–40% of patients with malignant pleural mesothelioma (MPM) carry inactivating mutations of NF2. In addition to NF2, BRCA1-associated protein-1 (BAP-1) has also been identified as a key genetic alteration in mesothelioma. Recently, a new familial cancer syndrome associated with germline mutations in BAP1 was proposed, which includes MPM, ocular melanoma, and other cancers. However, NF2 mutations do not usually cause mesothelioma synchronous with schwannoma. We here report two cases of MPM synchronous with vestibular schwannomas and analytical finding on NF2 mutations
Methods:
Case 1 was a 65-year-old man with epithelioid MPM. A unilateral acoustic neuroma was resected in 2010 because the patient experienced progressive hearing loss in the right ear since 2000. In April 2012, right pleural fluid was detected on chest X-ray and a thoracoscopical examination was performed. Epithelioid MPM was diagnosed pathologically. Case 2 was a 72-year-old man with epithelioid MPM synchronous with unilateral acoustic neurinoma. The patient presented with DOE and hearing loss in the left ear that had progressed over the past month. Chest X-ray showed pleural effusion, and a biopsied specimen with thoracoscopy revealed epithelioid MPM. Brain MRI and CT showed a mass that was highly suspected to be acoustic neurinoma between the left cerebellopontine angle and the opening of the internal acoustic meatus. We performed whole-exome sequencing on DNA in tumor tissue and blood and immunohistochemical analysis of NF2 gene encoding protein merlin.
Results:
Both patients were diagnosed with synchronous acoustic neurinoma and epithelioid MPM. NF2 gene mutations were identified in both tumors of MPM and acoustic neurinoma in Case 1. And in Case 2, diagnosis of acoustic neurinoma was depended on typical findings of brain MRI/CT, for which surgical resection was not performed because of advanced stage of MPM. Tumor tissue of MPM in Case 2 showed positive result of NF2 mutation. Both patients had a history of asbestos exposure.
Conclusion:
Although the role of NF2 mutation as a possible disease-causing mutation in MPM and synchronous occurrence with schwannoma remain unclear, both cases showed the possible role of NF2 mutation in asbestos-related neoplasm. We will show the pedigree of the patients’ families.
