Targeting the ERβ/Angiopoietin-2/Tie-2 Signaling-Mediated Angiogenesis with the FDA-Approved Anti-Estrogen Faslodex to Increase the Sunitinib Sensitivity in RCC

Abstract

Sunitinib has been used as the first-line therapy to suppress the metastatic clear cell Renal Cell Carcinoma (ccRCC) as it could function via suppressing the tumor growth and angiogenesis. Yet most ccRCC tumors may still regrow due to the development of sunitinibresistance, and detailed mechanisms remain unclear. Here, we found the estrogen receptor β (ERβ) in RCC cells might function via increasing the endothelial cell tube formation to alter the sensitivity to sunitinib treatment. Mechanism dissection revealed that ERβ could function via transcriptional regulation with direct binding to the promoter to increase the cytokine Angiopoietin-2 expression in the ccRCC cells. The up-regulated Angiopoietin-2 could then increase the Tie-2 phosphorylation in the endothelial Huvec cells to promote the angiogenesis tube formation that results in increasing the endothelial cell resistance to sunitinib treatment. Preclinical study using an in vivo mouse RCC model also confirm in vitro data. Targeting this newly identified ERβ/Angiopoietin2/Tie-2 signaling-increased angiogenesis tube formation with the FDAapproved anti-estrogen, ICI 182,780 (Faslodex) may help in the development of a novel combined therapy with sunitinib to better suppress the ccRCC progression. Funding Statement: This work was partially supported by the URMC Urology research fund and the George Whipple Professorship Endowment. Declaration of Interests: The authors declare no potential conflicts of interest. Ethics Approval Statement: The Institutional Animal Care and Use Committee (IACUC) review board at University of Rochester Medical Center approved the studies.