*4.8. Statistical Analysis*

Differences in the expression of genes were evaluated by Student's t-test or one-way ANOVA. A *p* value less than 0.05 was considered statistically significant.

### **5. Conclusions**

Herein, we have reported that GC compound, an enantiomer of BTM-21-P and DXM-21-P, identified from a natural compound library, induces *TTP* expression in a GRdependent manner in breast cancer cells. Furthermore, we found that GR does not induce *FOXO1* expression but may stimulate FOXO1 to bind to the TTP promoter and thus to induce TTP expression. Importantly, GC-induced TTP down-regulated ARE-containing TTP target genes and mediated the anti-viability function of GCs. The inhibition of *TTP* by siRNA attenuated the anti-viability effect of GCs. Thus, our data indicate that GCs induce *TTP* expression in a FOXO1-dependent manner, and that GC-induced TTP mediates the anti-viability activity of GCs in breast cancer cells.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/ijms232213673/s1.

**Author Contributions:** J.W.P. designed experiments and wrote the manuscript. D.Y.J., S.Y.J. and J.W.L. performed most of the experiments and wrote the manuscript. J.K. (Jeonghwan Kim), B.A. and J.K. (Junil Lim) performed RNA-Seq analysis. J.H.K., H.S.C., W.J.J. and B.J.L. analyzed the results. S.H.C. designed experiments. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the National Research Foundation of Korea (NRF- 2014R1A6A 1030318).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Acknowledgments:** The chemical library used in this study was kindly provided by Korea Chemical Bank (http://www.chembank.org/. accessed on 26 January 2017) of Korea Research Institute of Chemical Technology.)

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

