Abstract 500: Role of R-spondin4 in Wnt/β-catenin signaling and cell proliferation in breast cancer.

R-spondin 4 (Rspo4) is a member of the Rspo protein family, which is another group of secreted proteins that can activate Wnt/β-catenin signaling. Although it is well recognized that Wnt/β-catenin signaling is important for breast cancer development and progression, the role of Rspo4 in breast cancer is unclear. In the present study, we found that Rspo4 was expressed in breast cancer cell lines, but absent in normal mammary epithelial cells (HMECs). We also found that Rspo4 expression was up-regulated in human malignant breast tissues. Moreover, Rspo4 acted synergistically with Wnt3A to activate Wnt/β-catenin signaling in breast cancer cells. Conversely, reducing endogenous Rspo4 with siRNAs in human breast cancer cell lines suppressed Wnt/β-catenin signaling and cell proliferation. These data suggest that Rspo4 functions as a positive regulator of breast cancer proliferation by activating Wnt/β-catenin signaling. Citation Format: Wenyan Lu, Cuihong Lin, Taj K. King, Yonghe Li. Role of R-spondin4 in Wnt/β-catenin signaling and cell proliferation in breast cancer. [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 500. doi:10.1158/1538-7445.AM2013-500