Abstract 2270: RAGE-ligand signaling drives breast cancer invasion and metastasis
Authors: Kwak Taekyoung , Drews-Elger Katherine , Zhao Dekuang , Besser Alexander , Ergonul Ayse , Slingerland Joyce M. , Lippman Marc E. , Hudson Barry I. 
Published: August 2015

Abstract
Background: Breast cancer is most common malignant state in women and 20% of these patients will develop metastasis during the course of their disease. Further understanding is needed of the process and mechanisms of metastasis. Our lab and others have been shown that Receptor of Advanced-Glycation End-products (RAGE) plays a role in tumorigenesis and metastasis. RAGE is highly expressed in various cancers including breast cancer and its protein levels correlate with poor patient outcome in breast cancer and other cancers. Activation of RAGE results in increased proliferation, migration and invasion of cancer cells. Further studies in mice have shown its blockade may be a therapeutic target to reduce tumor growth and the resulting metastasis.
Methods: Using the breast cancer cell model (MDA-MB-231) and its organotropic sister cells lines selected in vivo for increased metastasis to lung (4175) and bone (1833), we tested the role of RAGE in driving mechanisms of metastasis in vitro and in vivo.
Results: First, we demonstrated that the highly metastatic variant of 231 cells (4175 and 1833) have increased expression level of RAGE compared to MDA-MB-231 parental cells. Moreover, RAGE knockdown by shRNA in 4175 and 231 parental cells showed decreased cell invasion in transwell assays compared to control scramble shRNA. Ectopic over-expression of RAGE in parental 231 cells led to increased migratory and invasive properties compared to vector control cells, without affecting cell proliferation or viability. To explore the underlying mechanisms we probed for differences in RAGE signaling pathways including MEK/ERK, p38, AKT and SAPK/JNK; with MEK/ERK and Akt showing activation. Using chemical inhibitors of these pathways we demonstrated that the MEK/ERK, but not other pathways inhibited RAGE-driven cell invasion in transwell assays. To validate our data in vivo, we performed mammary fat pad injection of 4175 cells (RAGE and scr shRNA) in NSG mice. Tumor growth and weight was impaired in RAGE gene knockdown 4175 cells compared to scramble (scr) controls. Analysis of lung tissue retrieved from mice revealed RAGE knockdown in 4175 cells resulted in less metastasis compared to 4175 scr control cells.
Conclusion: We have shown that higher RAGE levels are seen in metastatic human breast cancer BC cells. RAGE gene knockdown in metastatic BC cells reduces their invasive properties in vitro and reduces tumor progression and metastasis in vivo in NSG mice.
These data highlight RAGE as a novel therapeutic target for metastatic disease in breast and other cancers.
Citation Format: Taekyoung Kwak, Katherine Drews-Elger, Dekuang Zhao, Alexander Besser, Ayse Ergonul, Joyce M. Slingerland, Marc E. Lippman, Barry I. Hudson. RAGE-ligand signaling drives breast cancer invasion and metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2270. doi:10.1158/1538-7445.AM2015-2270