Figure 2.

Different effects of QB102 on cell accumulation and sensitivity to different P-gp substrates. (a) Effect of QB102 on cell sensitivity to Adr and Taxol is P-gp-dependent. The results of colony assays carried out on P-gp positive (KB8-5-11) and P-gp negative (KB3-1) cells in constant to the presence of the indicated concentrations of the drugs. The effect of QB102 is dose-dependent. (b) QB102 (10 μM) has the opposite effect on cytotoxicity of Adr and Taxol and does not affect cell sensitivity to colcemide. Con A cells were growing 72 h in the presence of different concentrations of the indicated drugs with or without QB102, fixed with methanol, and stained with methylene blue. (c) QB102 has the opposite effect on accumulation of daunorubicin and Taxol. Con A cells were incubated 2 h with the indicated concentration of daunorubicin (Left) and Taxol (Right) and accumulation of the drugs was determined by flow cytometry (daunorubicin) or measurement of intracellular radioactivity ([³H]Taxol).