Effect of the Novel Prostaglandin A1 Derivative TEI-6363 on ROS17/2.8 Cell Differentiation In Vitro

The effect of TEI−6363(5−[E−4−N, N−dimethylaminophenylmethylene]−4−hydroxy−2−[1−methyl imidazole−2−ilthio]−4−[4−phenylbutyl]−2−cyclopentenone), a chemically synthesized prostaglandin 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 10-6M, and viable cells were counted to assess cytotoxic effects and determine the growth curve.After 96 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 10-6M TEI−6363 for 24 h or longer.A pulsetreatment experiment showed that TEI−6363 induced the inhibition of proliferating ROS17/2.8 cells 24 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 10-6M 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 phase and induced osteoblastic differentiation.These results did not appear to be dependent on a marked cytotoxic effect.