Abstract
Previously we reported irradiation-induced apoptosis in peritoneal resident macrophages (PM) of C3H mice but not other strains of mice. Furthermore, it was found that a well-known apoptotic pathway involving the activation of atm, DNA-PK and/or p53 induced by DNA damage did not take part in irradiation-induced apoptosis in C3H mouse PM and that the apoptosis was dependent on irradiation-induced depletion of Mcl-1, a Bcl-2 family protein. In the present study performed to confirm that DNA damage did not participate in irradiation-induced apoptosis in C3H mouse PM, however, it was found that DNA double-strand breaks could induce apoptosis in C3H mouse PM. The mouse PM were treated with DNA topoisomerase II inhibitor, etoposide or introduced with a restriction endonuclease, Pvu II by means of HVJ envelope vector kit (GenomeONETM) to generate DNA double-strand breaks. Unexpectedly, these treatments induced marked apoptosis in C3H mouse PM, but not in radioresistant B6 mouse PM. Therefore, it is concluded that irradiation-induced apoptosis in C3H mouse PM is attributable to irradiation-induced DNA damage, possibly DNA double-strand breaks.
