|HOME SCHEDULE PROGRAM AUTHOR INDEX SUBJECT INDEX SIGN UP|
(PP349) In vitro protection against ionizing radiation by the novel radioprotectant ON01210.
Perkins, Michael*,1, Kumar, K. Sree1, 1 Radiation Casualty Management Team, Bethesda, MD, US
ABSTRACT- The radioprotectant drug ON 01210, Novonex/Ex-Rad (4-carboxystyrl-4-chlorobenzylsulfone), a member of the benzyl styryl sulfone family, exhibits radioprotective properties by the inhibition to various cellular pathways. Several analogs of benzyl styryl sulfones were found to have significant anticancer activity against a broad spectrum of cancer cells with low toxicity to normal cells. Unlike other known sulfhydryl radioprotectants such as amifostine, which are known to be toxic, ON01210 is not toxic to animals even at doses higher than the radioprotective doses. To understand the mechanisms of radioprotection by ON01210, we have studied its role in protecting cellular DNA by using alkaline comet formation as a measurement for doubled stranded DNA damage and some of the cellular events signaled by the ATM (ataxia telangiectasia mutated) gene. The role of the ATM gene in ON01210 protection was studied by using RNAi (RNA interference), because the ATM gene is known to be a key regulator of the DNA damage response and results in radiation sensitization. HFl-1 cells were irradiated bilaterally with 60Co at doses ranging from 1-9 Gy with a dose rate of 0.6 Gy/min. Cell survival of ON01210 treated and untreated HFL-1 cells were assessed using the colony formation assay. A 40-50% increase in cell survival was observed in cells incubated with ON01210 24 hr. before irradiation, in comparison to vehicle and untreated cells. The Trevigen comet assay was utilized to assess DNA damage to HFL-1 cell immediately after irradiation. Comet tail length of ON01210 treated, vehicle treated and untreated cells revealed a significant decrease of comet movement in ON01210 treated cells. Exponentially growing HFL-1 cells were transfected with 100 nM of ATM siRNA (small interfering RNA) in Lipofectamine for 24hrs, irradiated (1-9 Gy), washed, and after 7 days surviving colonies were counted and compared with untreated cells. None of ATM-inhibited HFL-1 cells survived, suggesting that silencing of the ATM gene increased the cytotoxic effects of ionizing radiation. Cell survival and comet assay studies indicated that ON01210 protected HFL-1 cells from ionizing radiation. Additional mechanistic studies involving NFkB and antioxidant enzymes in HFL-1 cells treated with ON01210 are in progress.
Key words: rna interference, ataxia telangiectasia, benzyl styryl sulfone, small interfering rna
Internet Services provided by|
Allen Press, Inc. | 810 E. 10th St. | Lawrence, Kansas 66044 USA
e-mail firstname.lastname@example.org | Web www.allenpress.com