Figure 1.

Increased glycolysis and dysfunctional mitochondria in DOX-resistant breast cancer cells. (a) Enzymatic activities of respiratory chain complexes 1, 2, 3, or 4 and citrate synthase were measured by spectrophotometry. Results are presented as the ratio of respiratory chain complexes activity to citrate synthase activity (n = 6); (b) mitochondrial oxygen consumption was measured by high-resolution respirometry. Experiment was carried out in the presence of glutamate + malate (complex I, n = 5), succinate (complex II, n = 6), or TMPD + ascorbate (complex IV, n = 9) and ADP as substrates; (c) holoenzyme for mitochondrial complex 1, 2, 3, and 4 was analyzed by BN Page. Results are presented as the ratios of complex 1, 3, or 4 holoenzyme content to complex 2 holoenzyme content (n = 6); (d) respiratory chain supercomplexes assembly was determined by Blue Native Page. Results were expressed as a ratio to complex II amount. (e) The levels of lactate production and glucose consumption were measured by spectrophotometry. Results are presented as the ratio of lactate production to glucose consumption (n = 21). The data are presented as mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.005.