Cell Cycle Kinetics and Metabolism of Ehrlich Ascites Tumor Cells in the Presence of Chloramphenicol as Inhibitor of Mitochondrial Protein Synthesis

Abstract

In the presence of 150(μ/ml of chloramphenicol, viability (dye exclusion test) of Ehrlich ascites tumor cells is not severely affected within 48 h; however the number of dead cells increases above this concentration; more than 10 mg/ml render all of the cells dye-positive within a culture period of 24 h. With the highest concentration tested (25 mg/ml) cells begin to lose viability 8 h after beginning of treatment. In the first passage in the presence of the antibiotic, proliferation of the cells is reduced by about 50%; in the second passage cell growth was about 65% that of controls. As is shown by flow cytometric analysis and BrdU-H33258 technique of flow cytometry, the reduction of proliferation in the second passage is caused by retardation of cell cycle progression of about 8 h; in the third passage the cell cycle is delayed by further 8 h as compared to controls. On recultivation in the third passage in the absence of the inhibitor an increase of cell number of about 75% of controls was observed. Lactate production and glucose uptake of the cells were stimulated by the inhibitor by about 20%; oxygen consumption was 60% that of controls after 24 h; however the ATP/ADP ratio of chloramphenicol treated cells was in the range of controls. Over a time period of 24 h the incorporation of [2-14C]thymidine is reduced to 34 ± 3%, incorporation of [2-14C]uridine was 88 ± 4% that of controls, incorporation of [U-14C]lysine was not significantly affected by 150 μg/ml of chloramphenicol; the same was found for the uptake of [2-14C]-α-aminoisobutyric acid. Electron micrographs of chloramphenicol treated cells reveal a high amplitude of swelling of all mitochondria with a translucent appearance of the inner compartment. The mitochondrial membranes remain largely intact but the number of cristae is drastically reduced.