YAMAMOTO Mika Showa University, Dept.of Dentistry, Research Associate, 歯学部, 助手 (30276604)
HANAZAWA Tomomi Showa University, Dept.of Dentistry, Research Associate, 歯学部, 助手 (20245872)
SANO Tsukasa Showa University, Dept.of Dentistry, Assistant Professor, 歯学部, 講師 (40241038)
|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥1,500,000 (Direct Cost : ¥1,500,000)
We investigated a mechanism for progression of cell differentiation by free radicals formed with ionizing radiation. As the activation of signal transduction is possibly involved in the progression of cell differentiation with radiation, we used inhibitors of signal transduction to investigate the mechanism.
1.MC3T3-E1 cells, an osteoblast-like cell line, were irradiated with x-ray with 10 Gy on culture day3. Alkalinphosphatase (ALP) activity, one of differentiation marker, in the cells was increased from culture day 12.2.Addition of 50 mM Genistein, a tyrosine kinase inhibitor, slightly increased ALP specific activity in non-irradiated cells. On the other hand, in irradiated cells, increase of ALP specific activity after irradiation was inhibited by Genistein, showing comparable activity to non-irradiated control cells. Therefore, Genistein showed a possibility to inhibit the increase of ALP specific activity by the irradiation. 3.Fifty mM H-7, a non-specific serin/threonin kinase inhibitor, inhibited the increase of ALP specific activity after irradiation, while protein kinase C specific inhibitor of Calphostin C at 0.1 mM did not. 4.Neomycin, a phospholipase C inhibitor, also did not affect the increase of ALP specific activity in irradiated cells.
The results suggest a possibility that increase of ALP activity in MC3T3-E1 cells induced by the x-ray irradiation is consequence of activation of tyrosine kinase in signal transduction of the cells. Furthermore, activation of serin/threonin kinases such as protein kinase A other than protein kinase C is possibly incorporated for the increase of ALP activity after irradiation.