Increased mitochondrial uptake of rhodamine 123 by CDDP treatment.
Rhodamine 123 (R 123) is a positively charged dye at physiological pH that accumulates specifically in the mitochondria of living cells without cytotoxic effect. In the present study, the uptake of R 123 by EL-4 lymphoma cells in culture with anticancer agents was measured by flow cytometry. Changes in R 123 uptake during the cultivation period were compared with cell distribution at different phases of the cell cycle. According to the increase in the proportion of S phase cells, mitochondrial synthesis increased, giving rise to a maximal fluorescence intensity of about 1.3-fold. Synchronous cultures showed the same relationship between increased mitochondrial uptake of R 123 and the S phase fraction as was observed in normal cultures. After treatment with 10(-3) M 5-fluorouracil (5-FU) for 1 h, EL-4 cells showed an increased binding of R 123 per cell followed by an accumulation of early S phase cells transiently. However, uptake of R 123 decreased 24 h later. On the contrary, after treatment with 10 micrograms/ml of cis-diamminedichloroplatinum (CDDP), a G2 + M block was observed from 12 h of reseeding and accumulation of the G2 + M cells continued. In this case, high uptake of R 123 continued during the observation period. From these results, mitochondrial synthesis seemed to increase according to the increment in proportion of S phase when the acceleration of the cell cycle turnover was augmented or the cycle was blocked in S phase by 5-FU. CDDP inhibited the cell division at G2 + M phase and caused increased R 123 fluorescence per cell. The stainability of R 123 may indicate the activity of cell division and may be a good way of evaluating the efficacy of antitumor drugs on the cells.
Shinomiya
N
N
Department of Microbiology, National Defense Medical College, Saitama, Japan.
Tsuru
S
S
Katsura
Y
Y
Sekiguchi
I
I
Suzuki
M
M
Nomoto
K
K
D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D004247:DNA / Q000032:analysis; D005453:Fluorescence; D005472:Fluorouracil / Q000494:pharmacology; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D020112:Rhodamine 123; D012235:Rhodamines / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D012235:Rhodamines; D020112:Rhodamine 123; D004247:DNA; D002945:Cisplatin; D005472:Fluorouracil