低濃度アレンドロネートはコネキシン43 活性を介して造骨系肉腫細胞株の局所浸潤能を増加させる

Bisphosphonates (BPs) are agents used for treating disorders of excessive bone resorption. In addition, due to their cell-killing activity, BPs were potent candidates for adjuvant cancer therapy. On the other hand, low-concentrations of BPs have been reported to increase cellular viability in several types of tumor cells. Therefore, we focused on the effect of BPs on cellular aggressiveness of malignant bone tumors at low concentrations. MTS assay was performed using osteosarcoma cell lines MG63 and HOS, fibrosarcoma cell line HT1080, and prostate cancer cell line PC3. All the cell lines showed toxicity at high concentrations. On the other hand, at lower concentrations, the cellular viabilities of HOS and MG63 were rather higher than those of untreated controls. Since this tendency was most evident, HOS was used for further assays, including cellular motility, bone resorption activity, and cathepsin K activity. The low-concentration of alendronate enhanced cellular viability and motility, which correlated with the expression of connexin 43 at the mRNA and protein levels. Interestingly, oleamide, a potent connexin 43 inhibitor, had an inhibitory effect on the enhanced proliferation. Our data suggest that alendronate may enhance the proliferation of osteoblastic cell line through connexin 43 activation.博士（医学）・乙第1296号・平成24年5月28日Copyright © 2011 Elsevier GmbH. All rights reserved

Genetic Heterogeneity among Strains of Treponema phagedenis-Like Spirochetes Isolated from Dairy Cattle with Papillomatous Digital Dermatitis in Japan ▿

Papillomatous digital dermatitis (PDD) is an infectious foot disease of cattle that is prevalent throughout the world. Although it has been prevalent in Japan since the first case was reported in 1992, full epidemiological and bacteriological examinations have not been conducted. We collected 91 lesions of PDD from 80 dairy cattle on 12 farms in eight regions of Japan to isolate the spirochetes that are frequently detected in lesions. We isolated 40 strains of spirochetes from 24 cattle (30.0%) by a simple two-step culture technique, in which the biopsy samples were incubated at 4°C for 48 to 72 h in an enrichment broth supplemented with antibiotics, which improved the rate of isolation, and then inoculated on selective agar plates. All spirochetes examined were catalase positive and oxidase negative and showed weak beta-hemolytic activity. Enzyme activities were identical to those of Treponema phagedenis ATCC 27087. Sequencing of the 16S rRNA gene showed that all strains isolated had >99% identity to those of the T. phagedenis type strain and of T. phagedenis-like strains isolated from PDD lesions in the United States and Europe. Pulsed-field gel electrophoresis and PCR-based random amplified polymorphism DNA methods revealed considerable diversity among strains isolated not only from different cattle but also from the same individuals. These findings may provide further evidence for the role of these treponemes in the pathogenesis of persistent PDD