Fig. 6.

Effect of TCDD pretreatment on expression of drug transporter genes in cells with unchanged sensitivity to cisplatin. (A) Hep3B and (B) MDA-MB-231 cells were pretreated with 10 nM and 5 nM TCDD, respectively, for two days and then treated with 5 µg/mL cisplatin for one day. Control cells were as described for Fig. 1. mRNA expression was detected by multiplex RT-PCR as described in Materials and Methods. Relative mRNA expression was evaluated in one independent experiment run in duplicate. Human GAPDH was used as an internal control. ^*P < 0.05; CTL, control; TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin; CDDP, cisplatin.