Figure 1

NRC-03 and NRC-07 are cytolytic for breast cancer cells, including chemoresistant variants. T-47D, MDA-MB-231, MCF7, SKBR3, and MDA-MB-468 breast cancer cells and 4T1 mouse mammary carcinoma cells were exposed to medium alone or the indicated concentrations of (a) NRC-03, (b) NRC-07, or (c) NRC-13. Cell viability was determined by MTT assay after 24 hours. Data shown are statistically significant by ANOVA (p < 0.005). (d) MCF7 or paclitaxel-resistant MCF7-TX400 cells were cultured in the presence or absence of 50 μM NRC-03, NRC-07, or NRC-13 for 24 hours. Percentage cytotoxicity relative to cells grown in medium alone was determined with acid phosphatase assay because of the interference of drug-efflux pumps with the reduction of MTT [27]. Cytotoxicity in cultures of NRC-03-, NRC-07, or NRC-13-treated MCF7 cells versus MCF7-TX400 cells was not statistically significant by the Student t test (p > 0.05). All data shown represent the mean of at least three independent experiments ± SEM.