Chemotherapy-induced changes in the energetics of human breast cancer cells; 31P- and 13C-NMR studies.

The early changes in the energetics of T47D-clone 11 human breast cancer cells, following treatment with adriamycin and several other anti-cancer drugs were characterized by 31P- and 13C-NMR spectroscopy. Treatment of the cells with cytotoxic doses of either adriamycin (10(-5) M), daunomycin (10(-5) M) or actinomycin-D (2 x 10(-6) M) induced an immediate increase in the content of the nucleoside triphosphate (NTP) pool. A maximum increase of 30 to 50% was reached 6 to 8 h after treatment, and was followed by a gradual decrease, in accord with the decline in cell number due to cell death. High-performance liquid chromatography measurements indicated that the adriamycin-induced build-up of the NTP pool was mainly due to a specific increase in ATP and GTP. Treatment with cytotoxic doses of cytosine arabinofuranoside (10(-4) M) and cis-platin (10(-4) M) and with the antiestrogen tamoxifen at a dose which inhibited growth (2 x 10(-6) M) did not induce an early increase in the NTP content. Adriamycin and actinomycin-D did not alter significantly the rates of glucose consumption and lactate production via glycolysis during the first 4 to 8 h of treatment. Both drug, however, caused during this time interval a 50% inhibition in the rate of glutamate synthesis via the Krebs cycle. Complementary flow cytometry studies have indicated that within 4 h of treatment with either adriamycin or actinomycin-D there is no detectable change in cell cycle distribution. Treatment for longer time periods indicated that each drug affects the cell cycle distribution in a different manner. Thus, the early increase in NTP can not be associated with a specific cell cycle distribution. The results suggest therefore that drugs of the anthracycline and actinomycin type exert a similar specific and early metabolic induction which may affect the energy state of the cells. This induction may relate to the cytotoxic mechanism and could potentially serve as an early marker for response to treatment.