COMPARATIVE ULTRASTRUCTURAL STUDIES OF NUCLEOLI OF TUMOR-CELLS TREATED WITH ADRIAMYCIN AND NEWER ANTHRACYCLINES, CARMINOMYCIN AND MARCELLOMYCIN

Abstract

This study was designed to determine the effects of several antitumor anthracyclines, including adriamycin and its analogs, carminomycin and marcellomycin, on the ultrastructure of nucleoli of Novikoff rat hepatoma cells. Adriamycin and carminomycin, which are structurally related, induce nucleolar segregation following the formation of conspicuous fibrillar centers. Marcellomycin did not induce formation of nucleolar fibrillar centers. Instead, numerous micospherules formed following treatment with marcellomycin. Later complete nucleolar segregation developed. The microspherules were in various stages of extrusion from the nucleolar body. This microspherule migration appeared to be time and drug concentration dependent. These results show that the rate and extent of nucleolar ultrastructural aberration may be related to structural differences of the various anthracyclines.