Daishiro Miura, Hiroshi Uno, Yoshiaki Azuma, Tomohiro Ohta*,#,
Mamoru Kiyoki and Yoshihiro Izawa
Teijin Institute for Bio-Medical Research, 4-3-2 Asahigaoka, Hino, Tokyo
191-8512, Japan
*ﾊTo whom correspondence should be addressed.
#ﾊPresent address for correspondence:
Pharmaceuticals Scientific Sales Promotion Department, Teijin Ltd., Iino
Bldg. 5F, 1-1, Uchisaiwaicho 2-chome, Chiyoda-ku, Tokyo 100-8585, Japan
Abstract: The effect of TEI-6363 (5-[E-4-N,ﾊNﾊ-dimethylaminophenylmethylene]-4-hydroxy-2-[1-methyl
imidazole-2-ilthio]-4-[4-phenylbutyl]-2-cyclopentenone), a chemically synthesized
prostaglandinﾊA1 derivative, on cell proliferation and osteoblastic
differentiation was investigated concurrently. ROS17/2.8 cells (a rat osteosarcoma-derived
cell line) were treated with TEI-6363 at two concentrations, 10-7
and 10-6ﾊM, and viable cells were counted to assess cytotoxic
effects and determine the growth curve. After 96ﾊh of treatment, there was
no evidence of any effect of TEI-6363 on cell viability at either concentration.
However, a clear inhibitory effect on cell proliferation was observed after
treatment with 10-6ﾊM TEI-6363 for 24ﾊh or longer. A pulse-treatment
experiment showed that TEI-6363 induced the inhibition of proliferating
ROS17/2.8 cells 24ﾊh after addition. The inhibition of proliferation was
associated with G1-arrest demonstrated by flow cytometric analysis, and
incorporation of [3H]thymidine by ROS17/2.8 cells was decreased.
Osteoblastic differentiation (assessed on the basis of increased alkaline
phosphatase activity and collagen synthesis) was induced by TEI-6363 treatment
at 10-6ﾊM following G1-arrest and inhibition of cell proliferation.
These results suggest that TEI-6363 arrested the cell cycle of ROS17/2.8
cells at the G1ﾊphase and induced osteoblastic differentiation. These results
did not appear to be dependent on a marked cytotoxic effect.
Keywords: Prostaglandin, Cyclopentenone, Osteoblast, G1 arrest, Differentiation