Cytotoxic effects of single and combination treatment of Tz and Se on Tz-sensitive and -resistant breast cancer cells.

(A) Microscopic image after Se treatment in SK-BR-3 and JIMT-1 cells for 72 h. (B) Response to Se with dose increase in SK-BR-3 and JIMT-1 cell lines. Cells were treated with distilled water (control), Se at 1 μM, 3 μM, 5 μM and 10 μM, or Tz 1 μg/mL combined with Se at 1 μM, 3 μM, 5 μM or 10 μM for 72 h. Viable cells were counted in a Neubauer chamber. Relative survival rates are shown as percentages of untreated control cells. Bars shows mean ± standard deviation of triplicates. Control group received vehicle only. One-way ANOVA followed by post Scheffe test was used for statistical analysis to compare between groups. (*P < 0.05; **P < 0.01 significantly different from control in each cell line; ^# P < 0.05; ^## P < 0.01 significantly different between both cell lines).