Apoptosis induction and cell-cycle change of human cancer cell-line caused by heavy-ions and X-rays

Abstract

The comparison between heavy ion beam and X rays for apoptosis induction ability on the cultured cells was conducted. The apoptosis induction and the cell cycle change after the irradiation were investigated using three human cell lines: MDA-MB231 (breast cancer origin), T24 (bladder cancer origin) and KB3-1 (epidermoid cancer origin). The heavy ion beam which was employed was a carbon beam at the energy of 290 MeV/u. A big shift to G2 was observed after the X ray (150 kV) irradiation, and this effect was dose-dependent. Apoptotic fraction increased with the dose, but it reached to a plateau around 50 to 60 percent at the dose of approximately 15 Gy. The effect of the carbon beam irradiation on these cell lines was very similar to that of X ray. G2-block was observed after the carbon beam irradiation, and the apoptosis with dose dependence occurred and then reached to a plateau around 60-80 percent at the dose of approximately 4 to 6 Gy. The reason why such different effect was observed by heavy ion beam and X ray can not be explained now.

培養細胞のアポプトーシス誘導能に対する重イオンビームとX線について比較した。3種類のヒト細胞株MDA-MB231(肺癌起源)、T24(膀胱癌起源)ならびにKB3-1(扁平上皮細胞癌起源)を用いて、照射後のアポプトーシス誘導と細胞周期の変化を調べた。使用した重イオンビームは290MeV/uの炭素ビームである。X線(150kV)照射を行うと、G2への大きな移行が観察され、この効果は線量に依存した。アポプトーシスの画分は線量に伴って増大したが、およそ15Gyの線量のところで50?60%前後のプラトーに達した。炭素ビーム照射がこれらの細胞株に及ぼす影響はX線の場合に非常によく似ている。G2ブロックが炭素ビーム照射後に観察され、線量に依存するアポプトーシスが生じ、次いで約4?6Gyの線量において60?80%前後でプラトーに達した。重イオンビームとX線によりこのような異なった効果が観察される理由は今のところ説明できない。