Potential Mechanisms for Protective Effect of D-Methionine on Plasmid DNA Damage Induced by Therapeutic Carbon Ions.

Potential Mechanisms for Protective Effect of D-Methionine on Plasmid DNA Damage Induced by Therapeutic Carbon Ions.
Radiat Res. 2020 Mar 27;:
Authors: Yogo K, Murayama C, Fujisawa Y, Maeyama T, Hirayama R, Ogawa Y, Matsumoto KI, Nakanishi I, Yasuda H, Ishiyama H, Hayakawa K
Abstract
D-methionine (D-met), a dextrorotatory isoform of the amino acid L-methionine (L-met), can prevent oral mucositis and salivary hypofunction in mice exposed to radiation. However, the mechanism of its radioprotection is unclear, especially with regard to the stereospecific functions of D-met. Radiation is known to cause injury to normal tissue by triggering DNA damage in cells. Thus, in this study we sought to determine whether the chirality of D-/L-met affects radiation-induced events at the DNA level. We selected plasmid DNA assays to examine this effect in vitro, since these assays are highly sensitive and allow easy detection of DNA damage. Samples of supercoiled pBR322 plasmid DNA mixed with D-met, L-met or dimethylsulfoxide (DMSO) were prepared and irradiated with a Bragg peak beam of carbon ions (∼290 MeV/u) with a 6-cm spread. DNA strand breaks were indicated by the change in the form of the plasmid and were subsequently quantified using agarose gel electrophoresis. We found that D-met yielded approximately equivalent protection from carbon-ion-induced DNA damage as DMSO. Thus, we propose that the protective functions of methionine against plasm...

Source: Radiation Research - March 26, 2020 Category: Physics Authors: Yogo K, Murayama C, Fujisawa Y, Maeyama T, Hirayama R, Ogawa Y, Matsumoto KI, Nakanishi I, Yasuda H, Ishiyama H, Hayakawa K Tags: Radiat Res Source Type: research