Proliferative behaviour of high-ploidy cells in two murine tumour lines.

The presence of high-ploidy cells in malignant tumours has long been documented. However, the biological significance of these cells is not known and there is a great deal of controversy over their proliferative potential. We have analysed the behaviour of these cells in two murine tumour lines, B16F10 melanoma and 3T3A31M angiosarcoma, determining their DNA content by microspectrophotometry and using time-lapse film studies. We have found a discrepancy between the presence of high-ploidy cells in metaphase and the absence of hyperploid telophases. High-ploidy metaphases may be aborted (mitotic polyploidization), prolonged in time or evolve in the form of multipolar, generally tripolar, mitoses. Our results suggest that high-ploidy cells are capable of proliferating, despite certain peculiarities in their cell cycle, and constitute a tumour subpopulation whose role in neoplasia merits further study.