ラット皮下移植グリオーマにおける放射線，ACNU及びO6-Ethylguanineの併用効果

Effect of X-rays Combined with ACNU and O6-Ethylguanine on Rat Subcutaneous Gliomas

I．はじめに

　悪性グリオーマの治療には，手術療法に，放射線療法，化学療法，免疫療法の併用が行われ，治療成績の改善が報告されつつあるが^{10,18,32,34）}，満足のできる成績ではない．その理由の一つにヒト悪性グリオーマ細胞がヒト悪性腫瘍細胞の中で，最も放射線抵抗性であることが挙げられる^9）．このため脳の放射線耐容線量限度内で局所制御を達成するには，併用療法による効果の増強が望まれる．そこで我々は悪性グリオーマに対する補助療法として，放射線療法と化学療法として，1-（4-amino-2-methyl-5-pyrimidinyl）methyl-3-（2-chloro-ethyl）-3-nitrosourea hydrochloride（ACNU）と5-fluorouracil（5-FU）の併用を行ってきた．

Abstract

Rat gliomas of subcutaneously transplanted RGc - 6 cells were irradiated with X-ray either alone, or com-bined with ACNU, and the cell-survival was assayed in vitro. Cell-survival curve composed of two components by X-irradiation alone indicated the presence of a hypox-ic cell fraction. We have previously shown that com-bined treatment with ACNU apparently made the effect of X-ray on spheroids in vitro of the same cell line of RGc - 6 more powerful. Although treatment of rat gliomas with ACNU administered at 2 hrs prior to X-irradiation was most effective, it resulted in only the additive effect of the independent action of the two agents. Further treatment by 06 - ethylguanine prior to ACNU administration and X-irradiation apparently in-creased the strength of the effect of ACNU combined with X-ray to the dose-modifying factor for X-ray of 1.8. The result indicated that the combination of (r -ethylguanine prior to ACNU administration and X-irradiation may clinically enhance the effect of X-ray against apparent ACNU-resistant glioma cells such as RGc - 6 cells.