Effects of camptothecin, an inhibitor of DNA topoisomerase I on ribosomal gene structure and function in TG cells
- 1 January 1992
- journal article
- Published by Wiley in Biology of the Cell
- Vol. 74 (3) , 281-286
- https://doi.org/10.1016/0248-4900(92)90039-4
Abstract
The effects of camptothecin treatment and topoisomerase I inhibition on ribosomal gene structure and function were investigated in TG cells, a human tumour cell line. 90- and 180-min treatments with 25 microM camptothecin resulted in an increased DNA fragmentation and decreased activity of topoisomerase I in cell extracts. After 180-min treatment, the incorporation of labelled uridine into total cell RNA was reduced to 39% and the ribosomal RNA synthesis to 10%, as compared to values of control cells. At the ultrastructural level, the nucleolar components appeared to be segregated; after selective DNA staining, with osmium-amine complex, a part of the nucleolar chromatin of treated cells showed the presence of thin, extended DNA filaments, superimposable to those present in control cells.Keywords
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