第686回　千葉県がんセンター研究局集談会のお知らせ

演題： がん幹細胞を標的とした重粒子線がん治療の可能性
Possibility of Cancer Stem Cell Targeting Heavy-Ion Radiotherapy

演者： 崔 星 博士（放射線医学総合研究所 重粒子医科学センター・粒子線生物研究グループ・主任研究員）
Sei Sai, MD., Ph.D.
Heavy ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences

日時： 平成22年1月13日（水曜日） 午後4時30分～午後6時

場所： 千葉県がんセンター西１階 TV会議室

要旨： 　To determine the effects of carbon ion radiation on cancer stem cells and its relation to radiocurability, human colon cancer cells HCT116 were used in vitro and in vivo. The relative biological effectiveness (RBE) value of carbon ion relative to X-rays was calculated at 2.0 in vitro (D10 survival fraction) and 3.82 in vivo (tumor regrowth delay). Both in vitro and in vivo FACS analyses showed that the percentage of cancer stem-like cells which positive for CD133, EpCAM, and CD44 were more significantly increased in a dose-related manner after X-ray compared to carbon ion irradiation . At an isodose of 30 Gy, carbon ion radiation predominantly induced xenograft tumor cell cavitation and fibrosis, whereas X-ray radiation only partially destroyed the tumor cell mass. Tumor-supplying blood vessels were markedly reduced in mice following carbon ion irradiation compared to the mice irradiated with X-rays. The expression of cancer stem-like cell related markers or proteins, such as CD133, EpCAM, CD44, as well as HIF-1a were predominantly suppressed following carbon ion radiation. In contrast, X-rays actually increased the expression of these factors. In conclusion, heavy ion radiation can effectively disrupt cancer stem cells compared to conventional X-ray, implying that heavy ion radiation can be a powerful cancer stem cell targeting therapeutics.