Colcemid-induced apoptosis of cultured human glioma: electron microscopic and confocal laser microscopic observation of cells sorted in different phases of cell cycle.

The effect of the antitubulin agent colcemid on human glioma cells was investigated by sorting cells with different DNA content and subjecting them to confocal laser microscopy and transmission electron microscopy. The human glioma cell line U251MG was exposed to colcemid at a concentration of 0.05 microg for 16 h. Flow cytometric analysis revealed the accumulation of cells in S/G2M phase. Cells harvested from each of G0/G1 and S/G2M peaks were then analyzed by confocal laser microscopy and transmission electron microscopy. Confocal laser microscopy revealed that colcemid-treated cells harvested from the G0/G1 peak contained mitotic and apoptotic cells in addition to interphase cells. Electron microscopy confirmed that colcemid-treated cells in the G0/G1 peak had fragmented nuclei typical of apoptotic cells and mitotic cells with altered chromatin structure. Some mitotic cells obtained by mitotic shake-off after treatment with colcemid showed DNA strand breaks defined by in situ nick end labeling. The present study indicates that mitotic as well as interphase apoptosis occurs in U251MG cells following colcemid treatment.