ヒト悪性神経膠芽腫細胞への超高圧X線照射の影響

LINAC RADIATION EFFECT ON HUMAN GLIOM AND GLIA CELLS

緒言

　悪性脳腫瘍の手術的療法には限界があり，成績が悲観的である場合が少くない。このため近年は放射線療法と制癌剤の応用が注目されつつある。

　われわれは悪性脳腫瘍に対し手術療法と共に超高圧X線療法を行なつて既に6年以上を経ているが，その遠隔成績は必ずしも満足出来るものでない。放射線療法によつて，より良き臨床成績を得るためには，より効果的な放射線治療を確立する必要があると考えられる。

Radiation effects on glioma and glia cells were obseved. As the materials, KS-1 cells line which has still maintain the properties of malignant cells from the central nervous system at the 41st passage (14 months cultivation), and glia cells derived from normal human fetus (15 weeks) were used.

Results ;

1) Mean lethal dosis (LDo) of KS-1 cells was supposed to be 700-800 R.

2) Remarkable difference of radiation effect was observed between 200-600 R and above 700-1000 R. Therefore, 700 R was considered to be critical point on KS-1 cells.

3) Single exposure of 700 R on KS-1 cells in-hibited the growth curve to 1/2, DNA content to 1/2, DNA metabolism to 1/2, LDH activity to 1/2 comparing from control (non-radiated group) at the 7th post-radiated day.

On the other hand, glucose effect increased about twice as control at the 7th post-radiated day.

4) Mean lethal dosis of normal human fetal glia cells was supposed to be 1000-1200 R. Although the single exposure of 700 R on these cells also in-hibited the growth curve about 1/2 of control, noremarkable difference from exposure of 500 R, as seen on KS-1 cells.

Therefore, it is concluded that the smallest and the most effective dosis of single exposure on KS-1 cells, and the same time with the least damage on normal human fetal glia cells is 700 R.

5) Radiation effect of 700 R × 2/w and 200 R × 7/w on KS-1 cells and human glia cells were com-pared by growth curve, resulting 700 R × 2/w showed some more effective than 200 R × 7/w.

This fact suggests that the clinical radiation dosis or method of fractional radiation should be recon-sidered.