Fig. 1
KLF9 is downregulated in breast tumors and induced by CORT in BCa cell lines. A KLF9 expression in breast cancer (BCa) samples relative to normal tissue equivalents based on analysis conducted using the GEPIA web tool [36] (TPM = transcripts per million; BRCA = breast cancer). B KLF9 expression evaluated across BCa molecular subtypes assessed using the bcGenExMiner v4.7 tool [37] (Welch’s test: P < 0.0001, followed by Dunnett-Tukey–Kramer’s test for multiple pairwise comparisons: P < 0.05; boxplots with different letters are significantly different). C Baseline expression of KLF9 in the three breast epithelial cell lines as measured through RT-qPCR (one-way ANOVA; P = 0.0004). D MCF10A, MCF7, and MDA-MB-231 cells were treated with increasing concentrations of CORT for 2 h. In MCF10A and MDA-MB-231, dose-dependent increase in KLF9 transcript levels was observed upon CORT treatment. In MCF7, a significant increase in KLF9 mRNA was observed only at 300 nM CORT (one-way ANOVA; MCF10A, MDA-MB-231: P < 0.0001; MCF7: P < 0.0405). E MCF7 cells were treated with increasing doses of E2 for 24 h. KLF9 expression remained unchanged with E2 treatment across all concentrations (one-way ANOVA; P = 0.231). Dose–response curves in the CORT treatment were fitted by nonlinear regression and dots represent the log2(fold induction) ± SEM while bars represent mean ± SEM with statistical significance indicated by letters above the means [CORT treatment: MCF10A (lowercase), MCF7 (uppercase), MDA-MB-231 (overline)] in one-way ANOVA followed by Tukey’s post-hoc test: P < 0.05; means with the same letter are not significantly different. All experiments were performed with N ≥ 3 replicates