Fig. 1
From: Identification and targeting of selective vulnerability rendered by tamoxifen resistance
TMX resistance in breast cancer patient samples and cell lines is associated with elevated SULT1A1 expression. a Heatmap of SULT1A1 and SULT1A2 genes differentially expressed in matched primary tumor and liver metastasis samples from breast cancer patients as assessed by RNA-seq. SULT1A1 expression is stronger in the liver metastasis, sampled after TMX treatment. b SULT1A1 mRNA expression and protein level were analyzed in MCF7-WT and its TMX-resistant (TMXR) derivative LCC2 cells, using qRT-PCR (***p < 0.001, Student’s t test) (left panel), WB (right panel), and immunofluorescence (low panel). The asterisk indicates non-specific band detected by SULT1A1 (ab191069) antibody. c SULT1A1 deletion (blue bars, #10) in spontaneous TMXR clone of MCF7 cells (red bars) confers sensitivity to 6 μM 4OH-TMX, as determined by resazurin assay (***p < 0.001, one-way ANOVA with Bonferroni’s multiple comparison test). d Immunofluorescence analysis of SULT1A1 protein (in green, using ab191069 antibody) after 6 days of 4OH-TMX treatment of breast cancer patient cells cultured in 3D ex vivo. e ImageJ quantification of total mean SULT1A1 intensity in samples treated as in d. Black, red, or blue dot represent patients K1, K2, and K3, respectively, (Table S1) (*p < 0.05, Student’s t test). f Induction of SULT1A1 expression in MCF7-WT cells treated with indicated concentrations of 4OH-TMX for 2 and 4 days, assessed by qRT-PCR (*p < 0.05, Student’s t test, comparison between 4OH-TMX versus DMSO treatment)