Abstract 1308: ERRβ ligand DY131 regulation of the hedgehog signaling pathway by modulation of Akt phosphorylation.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Nuclear receptor family member, Estrogen Related Receptor β (ERRβ), and hedgehog (Hh)-signaling are reported to be significant for both tumorigenesis and stem cell maintenance. ERRβ itself is a crucial factor in inducing pluripotent stem cells. Here we investigate the hypothesis that ERRβ can interact with Hh signaling pathway, and modulation of ERRβ can influence Hh signaling. NIH3T3 and HEK293 cells, transfected with a Gli response element driven luciferase reporter, were treated with different concentrations of DY131, a synthetic ERRβ ligand, in the presence or absence of exogenous ERRβ. We monitored the Gli reporter activity, as well as Gli1, Akt and phosphorylated Akt via western blot. Results: We found that DY131 inhibited Hh signaling activity when the pathway was activated by hedgehog peptide-conditioned medium, or the Smoothened Agonist (SAG), with an IC50 of 500nM. We also found that in HEK293 cells, where Gli reporter activity cannot be activated by either conditioned medium or SAG, DY131 dose dependently increased both endogenous and exogenous Gli1-induced reporter activity up to 4 fold. In addition, the transfection of ERRβ potentiated DY131’s effect on Gli reporter activity up to 7 fold. Western blot results, which are consistent with Gli reporter activity in both cell lines, showed that when Hh signaling is activated by Hedgehog peptide-conditioned medium, DY131 decreased Gli1 protein concentration; however when Hh signaling is not activated by conditioned medium, DY131 increases the concentration of Gli1 protein. Phosphorylated Akt, which is a non-canonical activator of Gli1, is up-regulated when Gli1 concentration increases, and down-regulated when the cells are treated with DY131. Conclusion: Our results suggest a new level of regulation by ERRβ on the Hh-signaling pathway. ERRβ, induced by DY131, can modulate Akt's regulation of Gli1. Additionally, our results indicate that modulation of ERRβ, via ERRβ selective drugs like DY131, may serve as a new target for Hh-driven cancer treatment. Citation Format: Yuan Lu, Benjamin R. Merideth, Hui Lin, Dennis B. Lubahn. ERRβ ligand DY131 regulation of the hedgehog signaling pathway by modulation of Akt phosphorylation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1308. doi:10.1158/1538-7445.AM2013-1308