Fig. 3.

Induction of the ABCG2 gene in cancer cells pretreated with TCDD. (A) SNU601, LS180 and CRT-MG cancer cells with acquired resistance to cisplatin were pretreated with 10 nM TCDD for two days. After which SNU601 and CRT-MG cells were treated with 5 µg/mL cisplatin and LS180 cells were treated with 10 µg/mL cisplatin for one day. (B) Hep3B and MDA-MB-231 cells with unchanged sensitivity to cisplatin were pretreated with 10 and 5 nM TCDD, respectively, for two days. Subsequently, all cells were treated with 5 µg/mL cisplatin for one day. Control cells were treated as described for Fig. 1. Gene expression was analyzed by real-time RT-PCR described in Materials and Methods. Results are represented as the mean ± SD from three independent experiments performed in duplicate. Human GAPDH was used as an internal control. ^*P < 0.05, ^**P < 0.01; CTL, control; TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin; CDDP, cisplatin.