Abstract
Ionizing radiation has been widely used as a tool for tumor treatment. However, there are still difficulties to treat the solid tumor with only irradiation. Several studies have been shown that the combination therapy using both X-irradiation and antitumor drug is more effective to tumor compared with X-irradiation only. Previously Noguchi et al. showed the Hsp90 (heat shock protein 90) inhibitor 17AAG (17 – allylamino – 17 – demethoxygeldanamycin) induced tumor cell death effectively with X-irradiation (Noguchi et al., Biochem Biophys Res Commun, 2006). Hsp90 is one of the enzymes activated by cellular stress and activates several tumor-related genes. Another way for tumor treatment is the irradiation of heavy ion such as proton or ion beam. Some electron accelerator facilities have been carried out for the radiotherapy for tumor. HIMAC (heavy ion medical accelerator in Chiba) in NIRS (National Institute of Radiological Sciences), one of the electron accelerator facilities, has been carried out the radiotherapy for tumor using carbon ion beam. The high energy of carbon beam would damage to tumor more effectively compared with X-rays. Moreover, the carbon beam has a characteristic to damage to the internal of tumor, not to the other normal organs in the body compared with X-rays. To clarify whether or not the combination therapy of carbon ion beam and 17AAG is effective to solid tumors, we tested the growth of solid tumor with the combination of X-irradiation and 17AAG in vivo and compared the results from in vitro study.
