• Tuberculosis and Respiratory Diseases
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• v.55 no.6
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• pp.597-611
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• 2003

Background : Loss of the short arm of chromosome 16 is a frequent event in various cancers, which suggests the presence of tumor suppressor gene(s) there. To map precise tumor suppressor loci on the chromosome arm for further positional cloning efforts, we tested 23 primary small cell lung cancers. Method : The DNAs extracted from paraffin embedded tissue blocks with primary tumor and corresponding control tissue were investigated. Twenty polymorphic microsatellite markers located in the short arm of chromosome 16 were used in the microsatellite analysis. Results : We found that six (26.1%) of 23 tumors exhibited LOH in at least one of tested microsatellite markers. Two (8.7%) of 6 tumors exhibiting LOH lost a larger area in chromosome 16p. LOH was observed in five common deleted regions at 16p. Among those areas, LOH between D16S668 and D16S749 was most frequent (21.1%). LOH was also observed at four other regions, between D16S3024 and D16S748, D16S405, D16S420, and D16S753. Six of 23 tumors exhibited shifted bands in at least one of the tested microsatellite markers. Shifted bands occurred in 3.3% (15 of 460) of the loci tested. Conclusion : Our data demonstrated that at least five tumor suppressor loci might exist in the short arm of chromosome 16 and that they may play an important role in small cell lung cancer tumorigenesis.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.171-180
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• 2001

Purpose : Expression of TIMP, intrinsic inhibitor of MMP, is regulated by signal transduction in response to genotoxins and is likely to be an important step in metastasis, angiogenesis and wound healing after ionizing radiation. Therefore, we studied radiation mediated TIMP expression and its mechanism in head and neck cancer cell lines. Materials and Methods : Human head and neck cancer cell lines established at Asan Medical Center were used and radiosensitivity $(D_0)$, radiation cytotoxicity and metastatic potential were measured by clonogenic assay, n assay and invasion assay, respectively. The conditioned medium was prepared at 24 hours and 48 hours after 2 Gy and 10 Gy irradiation and expression of TIMP protein was measured by Elisa assay with specific antibodies against human TIMP. hTIMP1 promoter region was cloned and TIMP1 luciferase reporter vector was constructed. The reporter vector was transfected to AMC-HN-1 and -HN-9 cells with or without expression vector Ras, then the cells were exposed to radiation or PMA, PKC activator. EMSA was peformed with oligonucleotide (-59/-53 element and SP1) of TIMP1 promoter. Results : $D_0$ of HN-1, -2, -3, -5 and -9 cell lines were 1.55 Gy, 1.8 Gy, 1.5 Gt, 1.55 Gy and 2.45 Gy respectively. n assay confirmed cell viability, over $94\%$ at 24hrs, 48hrs after 2 Gy irradiation and over 73% after 10 Gy irradiation. Elisa assay confirmed that cells secreted TIMP1, 2 proteins continuously. After 2 Gy irradiation, TIMP2 secretion was decreased at 24hrs in HN-1 and HN-9 cell lines but after 10 Gy irradiation, it was increased in all cell lines. At 48hrs after irradiation, it was increased in HN-1 but decreased in HN-9 cells. But the change in TIMP secretion by RT was mild. The transcription of TIMP1 gene in HN-1 was induced by PMA but in HN-9 cell lines, it was suppressed. Wild type Ras induced the TIMP-1 transcription by 20 fold and 4 fold in HN-1 and HN-9 respectively. The binding activity to -59/-53, AP1 motif was increased by RT, but not to SP1 motif in both cell lines. Conclusions : We observed the difference of expression and activity of TIMPs between radiosensitive and radioresistant cell line and the different signal transduction pathway between in these cell lines may contribute the different radiosensitivity. Further research to investigate the radiation response and its signal pathway of TIMPs is needed.