| Co-Investigator(Kenkyū-buntansha) |
SASAKI Akira UNIVERSITY HOSPITAL OF DENTISTRY, LECTURER, 歯学部・附属病院, 講師 (00170663)
NAKANISHI Toru OKAYAMA UNIVERSITY DENTAL SCHOOL, UNIVERSITY, ASSOCIATE PROFESSOR, 歯学部, 助教授 (30243463)
TAKIGAWA Masaharu OKAYAMA UNIVERSITY DENTAL SCHOOL, PROFESSOR, 歯学部, 教授 (20112063)
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| Budget Amount *help |
¥15,400,000 (Direct Cost: ¥15,400,000)
Fiscal Year 1999: ¥5,300,000 (Direct Cost: ¥5,300,000)
Fiscal Year 1998: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 1997: ¥6,200,000 (Direct Cost: ¥6,200,000)
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| Research Abstract |
Bone is one of the most common sites of metastasis in human cancer. The occurrence of osteolytic bone metastases causes serious morbidity due to intractable bone pain, pathological fractures, hypercalcemia and nerve compression syndromes declining the quality of life of cancer patients. Despite of the importance of these clinical problems, there is little information about the mechanism of bone metastases.
1. Establishment of Bone metastasis model induced by Oral Squamous Cell Carcinoma (SCC)
Several Oral SCC cell lines (HSC-2, 3, 4, Ho-1N1, HO-1u1, KB) were tested whether intracardiac injection of them could form the osteolytic bone metastasis. Only HSC-2 and 3 established bone metastasis foci. Interestingly, HSC-2 metastasized to not only bone but also the muscle and fascia. To determine the factors related to the bone metastases, we compared the differences of the expression of genes, proteins and others of all these cell lines. Both cell lines commonly showed the secretion of MMP-2 a
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nd -9, the expression of the integrin α2 and the degradation of E-cadherin which were previously described as the related factors to bone metastases. Although these factors may play an important role of bone metastases, it could not be concluded on which these were specific factors of bone metastasis. Therefore, the combination of these metastatic factors must be very important. In the other hand, a metastasis suppressor gene, nm23 H1 (NDP kinase A) was closely correlated to these both cell lines and human breast cancer cell MDA-231 that could form bone metastases.
2. In vivo selection of specific bone metastasis cell lines derived from Oral SCC
Intracardiac injection of HSC-2 metastasized to bone and muscle-fascia. Therefore, we attempted to select the subclones expressing a specific ability of metastasizing to bone and muscle respectively using in vivo selection. Consequently, we obtained two bone metastasis specific cell lines, HSC-2 OL (osteolytic) and HSC-2-BF (osteoformative). However, the muscle metastasis specific cell line was not selected. The HSC-2-OL inhibited the growth of osteoblastic cell line MC3T3-E1 and stimulated the formation and activity of osteoclasts. Although other cell lines showed the expression of BMP-2 and 4 genes, and the production of PTHrP, HSC-2OL did not produce them. Moreover, differential display analysis among HSC-2, HSC-2-OL and HSC-2-BF presented that the gene expression of HSC-2-OL was remarkably different from other two cell lines that showed the similar gene expression pattern each other. However, specific genes relating the bone metastasis has not been obtained. There are few experimental animal model presenting osteofomative bone metastatic lesions. Therefore, HSC-2-BF may provide the adequate model to investigate the mechanism of bone formation in bone metastasis. Less
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