Fig. 7

MIR2052HG-mediated SNP-dependent LMTK3 expression. a, b Androstenedione induction of MIR2052HG expression is associated with the expression of LMTK3. Five LCLs with either MIR2052HG WT or variant SNPs were exposed to treatments. LMTK3 expression levels were analyzed in each LCL and the averaged expression levels were shown for WT (n = 5) or V (n = 5) LCLs after exposure to androstenedione alone or with increasing concentrations of anastrozole (a) or exemestane (b). Error bars represent SEM. **p < 0.01. The concentrations for androstenedione (A), anastrozole (Ana), and exemestane (Exe) are indicated. c, d MIR2052HG SNPs determine androstenedione-dependent EGR1 binding to LMTK3 gene locus. ChIP assay using pooled LCLs (n = 5) with known genotypes for MIR2052HG SNPs demonstrates binding of EGR1 to LMTK3 gene locus after exposure to androstenedione alone or with anastrozole (c) or exemestane (d). Error bars represent SEM; **p < 0.01. e, f MIR2052HG SNP-dependent effect on AIs response. LCLs were treated with increasing dose of anastrozole (e) or exemestane (f) in the presence of 10 nM of androstenedione. Cell survival was analyzed 72 h after treatment for each LCL, and the averaged survival was shown for WT (n = 5) or V (n = 5) LCLs. Error bars represent SEM. *p < 0.05, **p < 0.01. g Effects of MIR2052HG-EGR1-LMTK3 on anastrozole response. Dose response of anastrozole in MCF7/AC1 and MCF7/AnaR cells. Cells were transfected with ASO or siEGR1, with or without overexpression of LMTK3 for 24 h, and then treated with anastrozole for 72 h. Error bars represent SEM. **p < 0.01. h Hypothetical model illustrated how MIR2052HG might regulate LMTK3 transcription. The red arrows indicate the transcription direction. The transcribed MIR2052HG interacts with EGR1 protein and brings EGR1 to the LMTK3 locus. Together with other transcription machinery, binding of EGR1 to the LMTK3 promoter initiates transcription. LMTK3 protein inhibits the PKC, therefore downstream MAPK and AKT/FOXO3 pathways, leading to regulation of ERα degradation and ESR1 transcription