Colcemid effects on B16 melanoma cell progression and aberrant mitotic division.

Mitotic cells selectively harvested after several h of colcemid treatment are routinely used to obtain synchronized cell cultures. DNA flow cytometry shows that when colcemid-treated B16 mitotic cells divide, they give rise to daughter cells in G1, some of which contain abnormal amounts of DNA. Two subpopulations appear to exist, one having a DNA content distribution expected of G1 cells, another having a mean DNA content about 0.8 of expected and an SD of DNA content more than 5 times expected. The effect was dependent on dose and duration of exposure to colcemid. Colcemid was more cytotoxic to cells in G2 + M than to G1 + S phase cells, and it slowed the progression of G1 cells to S. These effects of colcemid were much greater in aneuploid B16 melanoma cells than in pseudodiploid Chinese hamster ovary (CHO) cells.