Modeling ionizing radiation interaction with biological matter is a major scientific challenge, especially for protons that are nowadays widely used in cancer treatment. That presupposes a sound understanding of the mechanisms that take place from the early events of the induction of DNA damage. Herein, we present results of irradiation-induced complex DNA damage measurements using plasmid pBR322 along a typical Proton Treatment Plan at the MedAustron proton and carbon beam therapy facility (energy 137-198 MeV and Linear Energy Transfer (LET) range 1-9 keV/μm), by means of Agarose Gel Electrophoresis and DNA fragmentation using Atomic Force Microscopy (AFM). The induction rate Mbp-1 Gy-1 for each type of damage, single strand breaks (SSBs), double-strand breaks (DSBs), base lesions and non-DSB clusters was measured after irradiations in solutions with varying scavenging capacity containing 2-amino-2-(hydroxymethyl)propane-1,3-diol (Tris) and coumarin-3-carboxylic acid (C3CA) as scavengers. Our combined results reveal the determining role of LET and Reactive Oxygen Species (ROS) in DNA fragmentation. Furthermore, AFM used to measure apparent DNA lengths provided us with insights into the role of increasing LET in the induction of highly complex DNA damage.

• Klíčová slova
• Agarose Gel Electrophoresis (AGE), Atomic Force Microscopy (AFM), biodosimetry, clustered DNA damage, damage biomarkers, linear energy transfer (LET), proton therapy beam, scavenging capacity,
• MeSH
• DNA genetika   MeSH
• plazmidy genetika   MeSH
• poškození DNA MeSH
• protonová terapie * MeSH
• protony * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH
• protony * MeSH

DNA origami nanoframes with two parallel DNA sequences are used to evaluate the effect of nucleoside substituents on radiation-induced DNA damage. Double strand breaks (DSB) of DNA are counted using atomic force microscopy (AFM), and total number of lesions is evaluated using real-time polymerase chain reaction (RT-PCR). Enhanced AT or GC content does not increase the number of DNA strand breaks. Incorporation of 8-bromoadenosine results in the highest enhancement in total number of lesions; however, the highest enhancement in DSB is observed for 2'-deoxy-2'-fluorocytidine, indicating different mechanisms of radiosensitization by nucleoside analogues with the halogen substituent on base or sugar moieties, respectively. "Bystander" effects are observed, when the number of DSB in a sequence is enhanced by a substituent in the parallel DNA sequence. The present approach eliminates limitations of previously developed methods and motivates detailed studies of poorly understood conformation or bystander effects in radiation induced damage to DNA.

• MeSH
• adenosin analogy a deriváty   MeSH
• deoxycytidin analogy a deriváty   MeSH
• DNA * účinky záření   MeSH
• oprava DNA * MeSH
• poškození DNA MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 2'-fluoro-2'-deoxycytidine MeSH Prohlížeč
• 8-bromoadenosine MeSH Prohlížeč
• adenosin MeSH
• deoxycytidin MeSH
• DNA * MeSH