Abstract
Cell death induced in Meckel's chondrocytes in vitro with the anticancer drugs, etoposide and camptothecin, was examined from the viewpoint of an apoptotic event. Cell death was induced in vitro in Meckel's chondrocytes that were enzymatically isolated from 16-day gestation mouse embryos. The effects were assayed histologically and immunohistochemically by using the TUNEL procedure, and light and electron microscopy. Etoposide and camptothecin-treated cultures were followed by the strong appearance of TUNEL (TdT-mediated biotinylated dUTP nick end-labeling)-positive apoptotic cells; statistical analysis showed that these agents induced apoptosis significantly 12-24hrs after treatment. At an ultrastructural level, apoptotic cell death from etoposide was followed by the formation of cell blebs, chromatin condensation and the formation of apoptotic bodies. Immunostaining for p53 revealed that this protein was absent from intact chondrocytes but was continuously accelerated in the cells treated with etoposide and camptothecin. Bcl- 2 was immunolocalized in intact chondrocytes at an early stage of culture, but was not detected in anticancer-treated cells. In the present study, we confirmed that cell death in Meckel's chondrocytes induced by etoposide and camptothecin is typical apoptotic cell death, and that these agents also induce apoptosis in intact chondrocytes.
