Abstract 1729: Withaferin A blocks formation of IFN-γ-induced metastatic cancer stem cells through inhibition of the CXCR4/CXCL12 pathway in the UP-LN1 carcinoma cell model

Abstract

Abstract As our understanding of cancer stem cell (CSC) biology improves, there is an urgent need to search for inhibitory agents of CSCs and metastatic CSCs (mCSCs) positive for CXCR4. Withaferin A (WA), a withanolide extracted from the medicinal plant Withania somnifera, has been shown to exhibit anti-cancer effects through multiple mechanisms. Whether WA could selectively target CSCs, mCSCs, or non-CSCs of a gastrointestinal (GI) carcinoma tumor remains unclear. Side population analysis, flow cytometric phenotyping and sorting, non-invasive imaging in conjunction with xenotransplantation, and immunohistology were used in this investigation. Using the lymph node metastatic GI cancer cell line UP-LN1, consisting of CD44high/CD24low grape-like floating (F) and CD44low/CD24high adherent (A) cell subsets, this study demonstrated that, as compared with parental UP-LN1 cells or A cells, WA preferentially reduced F-cell proliferation, tumor sphere formation, and side population cells in vitro in greater efficiencies by apoptosis. This action was mechanistically mediated via the down-regulation of CXCR4/CXCL12 and STAT3/IL-6 pathways, both of which are instrumental in the acquisition of metastatic ability. Attenuation of IFN-γ-induced CXCR4 expression in F cells by knockdown with siRNA or blocking with anti-CXCR4 antibody, followed by Western blot analysis, showed significantly reduced metastatic potential in vitro. The extent of in vitro anti-invasive effect of WA on the IFN-γ-treated F cells was significantly greater than on the F cells without WA treatment, or F cells treated with control siRNA or with control IgG antibody. The observed in vitro effects of WA on the CSC and mCSC targeting were validated by data obtained with non-invasive imaging in NOD/SCID mouse xenotransplantation. We conclude that WA could efficiently block the formation of both CSCs and mCSCs in the UP-LN1 cell line, suggesting that WA may be considered an effective therapeutic agent for GI malignancies exhibiting grape-like tumor sphere. Citation Format: Andy Shau-Bin Chou, Li-Lei Ting, Chin-Hsuan Hsieh, See-Tong Pang, Shuen-Kuei Liao. Withaferin A blocks formation of IFN-γ-induced metastatic cancer stem cells through inhibition of the CXCR4/CXCL12 pathway in the UP-LN1 carcinoma cell model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1729.