Mitotic instability associated with late genomic changes in bone and soft tissue tumours

One source of genomic instability in tumours is abnormal mitotic segregation of chromosomes. Evaluation of chromosome segregation and cytogenetic aberrations in 28 bone and soft tissue neoplasms revealed few mitotic disturbances in benign lesions, whereas most of the malignant tumours, except for chondrosarcomas, showed anaphase bridges and/or multipolar mitoses. Only cases with chromosomal imbalances exhibited these defects and they were not present in any of the cases with sole primary changes, indicating that mitotic instability is established relatively late in mesenchymal tumour development. Most cases with multipolar mitoses exhibited abnormal centrosome configurations. However, induction of supernumerary centrioles in vitro failed to produce mitotic abnormalities in normal cells, indicating that additional disturbances of the cell division machinery are required for the generation of mitotic multipolarity.