Alterations in metaphase durations in cells derived from human tumours.

With the use of time-lapse cinemicrography, we previously found that metaphase durations were significantly prolonged in SV40-transformed human fibroblasts when compared to untransformed controls. This was consistent with some earlier reports and suggested that prolonged metaphases could account for high metaphase/prophase ratios and possibly, in part, for increased mitotic indices seen in advanced tumours. However, there are inconsistencies in the literature and no comparable data available from malignant carcinomas. Presented in this paper are data from two cervical dysplasias, two cases of carcinoma in situ, nine malignant carcinomas and several other types of human cells. The results show that mean metaphase durations were prolonged in cells derived from most of the carcinomas but not from the other cell types. On the other hand, cytokinesis appears to progress more rapidly than normal in most of the tumour-derived cells. These and other findings indicate that the changes are a result of some metabolic alteration common to many but not all tumour cells. For reasons presented, we suggest as a working hypothesis that the alterations may be due to changes in calcium regulation, possibly resulting from alterations in mitochondrial metabolism.