Fig. 4
From: Identification and targeting of selective vulnerability rendered by tamoxifen resistance
Inhibition of TrxR1 activity and induction of oxidative stress by RITA, AF, ONC-1 are SULT1A1-dependent. a SULT1A1-dependent induction of oxidative stress by 1 μM RITA (green), 3 μM AF (red), and 5 μM ONC-1 (blue) in HCT116 cells (24 h), but not in the derivative SULT1A1 KO lines. b, c Induction of oxidative stress in A375 (8 h) and SJSA (24 h) cells transfected with SULT1A1 cDNA, but not in vector-transfected cells after 1 μM RITA (green), 3 μM AF (red), and 1 μM ONC-1 (for A375) or 10 μM ONC-1 (for SJSA). Oxidative stress was measured using DCF-DA and followed by FACS analysis. d, e Histograms show the median ROS accumulation between compounds versus DMSO treatment, of n = 3 independent experiments in A375 (d) and SJSA (e) and *p  0.05 and ***p  0.001, one-way ANOVA with Bonferroni’s multiple comparison test. f Inhibition of TrxR1 activity in cell lysates after RITA (1 μM), AF (3 μM), and ONC-1 (5 μM) treatment for 6 h in HCT116 (left) and MCF7 TMXR (right) as measured using TrxR-dependent Trx-coupled insulin disulfide reduction assay. Shown is percentage of activity compared to control (DMSO)-treated cells (mean ± SD n = 2 of independent experiments and *p  0.05 and ***p  0.001, one-way ANOVA with Bonferroni’s multiple comparison test). g SULT1A1-dependent inhibition of TrxR1 activity in MCF7, but not in isogenic SULT1A1 KO cell lysates, as described in d, except that the cells were treated for 10 h. Shown is percentage of activity compared to control DMSO-treated cells (mean ± SD n = 2, *p  0.05 and ***p  0.001, ANOVA with Bonferroni’s multiple comparison test). h SULT1A1-dependent induction of covalent TrxR1 dimer, apoptosis, and DNA damage in HCT116 cells and in its derivative SULT1A1 KO, treated or non-treated with RITA, AF, and ONC-1. Immunoblot of SULT1A1 (ab124011), p53, TrxR1, PARP, and γH2A.X (S139) is shown; β-actin was used as loading control