Modification of radio- and thermo-sensitivity by amrubicin or amrubicinol in human lung adenocarcinoma A549 cells

Amrubicin (AMR) is a totally synthetic 9-aminoanthracyclin anticancer drug. It is considered that AMR is an inhibitor of DNA topoisomerase II as the case of another anthracyclin anticancer drug, adriamycin (ADM) (1), which has significant antitumor activity against a broad spectra of human malignancies. The antitumor activity of AMR was found superior to that of ADM in experimental therapeutic models of human tumor xenografts (nude mouse). AMR was converted in vivo to major metabolite, amrubicinol (AMROH), which was markedly more effective cytotoxic agent than the mother compound. In the clinical studies currently conducted on malignant lymphoma, non-small or small cell lung carcinoma, the activity of AMR was shown very promising. However, the interactive cytocidal effects of the combined treatment with AMR or AMROH and radiation or hyperthermia are under investigation. In the present study, we examined chemical modification of radio- and thermo-sensitivity by AMR or AMROH in cultured human lung adenocarcinoma A549 cells. Sublethal damage repair (SLDR) was inhibited by the pretreatment with AMR or AMROH followed by X-irradiation. This finding suggests the possibility of the combined treatment of AMR or AMROH and X-irradiation as clinical cancer therapy strategy, since the doses in the routine clinical radiotherapy is ranged with a sublethal dose of 2 Gy. We also found that SLDR was inhibited by the pretreatment with AMR or AMROH followed by hyperthermia. We will discuss about clinical adoption of the combined treatment with AMR or AMROH and radiation or hyperthermia