Radiation-induced DNA damage and repair in cell transformation

It is well known that high-LET radiations have higher carcinogenic potencies than low-LET radiation. They have used X rays and a variety of monoenergetic particle beams to study the mechanisms of neoplastic cell transformation in vitro. The LET of fast heavy nuclei is proportional to the square of the electric charge of the particles and inversely proportional to their velocity. Their conclusions are that there are great similarities in the relationship between RBE and LET for radiation-induced cell transformation, chromosome mutation and lethal effects. Individual heavy ions are capable of producing clusters of lesions in DNA and in chromatin, and the essential steps in the transformation process may relate to misrepair and to incomplete repair of such lesions. Nonhomologous repair appears to have an important role in the cell transformation process; their current investigations are directed at isolating this process and characterizing its molecular parameters