Effets de la mitomycine c et du melphalan sur les protéines nucléaires totales et les acides désoxyribonucléiques chez des fibroblastes de rat cultivés in vitro

Abstract

The effects of Mitomycin C and the aromatic nitrogen mustard Melphalan on total nuclear proteins, nucleolar dry mass and DNA in rat fibroblasts cultivated in vitro have been studied by means of microinterferometry and cytophotometry after Feulgen reaction. With these techniques, the quantity of the three nuclear components can be measured in individual cells and successively in the same cells. Previously, Mitomycin C and Melphalan had been shown to inhibit cell multiplication and to cause important cytological alterations during interphase and mitosis. As far as total nuclear proteins, nucleolar dry mass and DNA are concerned, the effects of Mitomycin C (0.4 mg/1, during 4 days) and of Melphalan (100 mg/1 during 3 days) are quite similar. Indeed, in the presence of one or another of these antimitotic agents, premitotic syntheses of nuclear proteins, nucleolar material and DNA take place; however, DNA synthesis seems to be somewhat inhibited by Mitomycin C. In both cases only a few cells divide. In these fibroblasts, the amount of total nuclear proteins and the nucleolar dry mass increase up to twice the normal pre-division value, while the DNA content is at the premitotic level. Probably due to inhibition of DNA synthesis, the majority of the Mitomycin C treated cells remain in this state. In the case of Melphalan, the DNA content continues to increase and the cells become octoploid and even sometimes hexadecaploid as far as DNA and nuclear proteins are concerned. The size of the fibroblasts treated by Mitomycin C or by Melphalan increases progressively and the cells slowly degenerate.