New approach to brain tumour chemoradiotherapy with cellular synchronization by colcemid.

Cellular synchronization using Colcemid as pretreatment for combined chemoradiotherapy was investigated. C6 rat brain tumour was cultured in RPMI medium containing 10(-5)-10(-7) Mol. of Colcemid for 24 hours. The basic cell kinetics were analysed with a Pulse Cytophotometer, which facilitated the analysis of tumour cell cycle phase distribution according to the DNA content. The effect of Colcemid depended on the concentration, and the minimal concentration showing continuous blocking during 48 hours after removal of the drug was 10(-6) Mol. G1 fraction of 2 C DNA content was reduced from 74% to 36%. G2-M phase of 4 C DNA content increased from 9% to 28%. S phase cells increased from 17% to 31%. Polyploid cells in the Tetraploid cell cycle could be recognized. The remaining 36% of cells within the GO + G1 peak of 2 C DNA content were considered to be diploid GO cells.