Fig. 4
LEM4 promotes tamoxifen resistance in ER positive breast cancers. a Western blot was performed with LEM4 antibody in MCF7 and MCF7-TAMR cells. b The GEO GSE100075 was downloaded from Gene Expression Omnibus (GEO).The expression level of LEM4 in MCF7, MCF7-LTED-ESR1(WT), and MCF7-LTED-ESR1(Y537C) cells was measured by transcription per million (TPM). c LEM4 siRNA and control siRNA treated MCF7-TAMR cells were treated with or without tamoxifen (1.0 μΜ) for 5 days. Total cell viability were assessed by SRB assays. Experiments were repeated three times, each experiment was triplicates. d A cellular viability assay was performed in MCF7-LEM4 and MCF7-vec cells treated with various concentrations of 4-OHT for 7 days. e BT474-shcontrol and BT474-shLEM4 cells were treated with various concentrations of 4-OHT for 7 days. Cellular viability was assessed by SRB assays. f Tumor growth and tumor weight of MCF7-vec and MCF7-LEM4 cells as subcutaneous xenografts in athymic mice with E2 supplementation until tumors reached 100 mm3, then treated with or without tamoxifen (TAM) pellets implanted subcutaneously for 30 days. Mean ± s.e.m., n = 8. g Tumor growth of BT474-shControl and BT474-shLEM4 cells as subcutaneous xenografts in athymic mice with E2 supplementation until tumors reached ~200 mm3, then treated with tamoxifen pellets implanted subcutaneously. Mean ± s.e.m., n = 7. h Three breast cancer datasets (GSE2990, GSE3494 and GSE9195) were from the KM Plotter database (www.kmplot.com). Kaplan–Meier analysis of recurrence-free survival in the cohorts of patients treated with adjuvant tamoxifen monotherapy (exclude all chemotherapy). Samples were stratified into “high” and “low” LEM4 expression based on median cutoff value in each dataset. P-values were calculated by the log–rank (Mantel–Cox) test. n.s., not significant, *P < 0.05, **P < 0.01 Tukey’s multiple comparisons test for b, f (weight). Repeated measures ANOVA for g (volume), Student’s t-test for g (weight)
