Abstract 3016: Characterization of cancer stem-like cells derived from mouse induced pluripotent stem cells transformed by tumor-derived exosomes/microvesicles

Abstract

Abstract It is widely accepted that the microenvironment/niche exert genetic and/or epigenetic effects on stem cells. Current studies have demonstrated that an aberrant microenvironment may contribute to the genesis of cancer stem cells (CSCs). In the case of cancer, growing evidence indicate a cancerous niche can play an active role in the regulation of tumor cell maintenance and progression through exosomes/microvesicles-based intercellular communication. It has not been reported, however, whether this vesicle-mediated communication induces the malignant transformation of normal stem cells/differentiating progenitors, result in CSC generation. Recentry, we have reported that the conditioned medium derived from the mouse Lewis Lung Carcinoma (LLC) cell line can convert mouse induced pluripotent stem cells (miPSCs) into CSCs. Here, we investigated the contribution of tumor-derived exosomes/microvesicles (TEMVs) that are secreted from LLC cells to induce the transformation of miPSCs into CSCs. The differentiating miPSCs were exposed to TEMVs derived from LLC cells for 4 weeks. We used Nanog-GFP miPS, in which GFP expression is under control of Nanog promoter, indicative of undifferentiation state. During this period, we observed the reemergence of the GFP-positive colonies, whereas most of cells were differentiated and GFP-negative without TEMV-treatment. The resultant TEMVs treated cells (miPS-LLCemv) expressed Nanog and Oct3/4 proteins comparable to miPSCs assessed by Western blotting. The sphere formation of the miPS-LLCemv cells in suspension culture indicated the selfrenewal capacity of the miPS-LLCemv cells. When the miPSLLCemv cells were subcutaneously allografted into immunodeficient mice, malignant tumors with extensive angiogenesis developed. Phathological features such as vementin, Ki67, PPAR gamma expression, and accumulation of lipid droplets in tumor revealed these tumors were liposarcomas. Tumor cells established from liposarcomas showed the capacity of spheroid formation in suspension culture and the capacity of differntiation into adipocytes and endothelial cells. These results indicate that miPS-LLCemv cells and established tumor cells possess CSC properties. Interestingly, these cells expressed Sox2 and Klf4 genes significantly higher than parental miPS cells, might be related to selfrenewal and addipogenesis. Thus, we concluded that TEMVs should have the potential to induce CSC properties in normal stem cells. Citation Format: Yan Ting, Junko Masuda, Akifumi Mizutani, Ling Chen, Tsukasa Shigehiro, Shuichi Matsuda, Tomonari Kasai, Takayuki Kudoh, Hiroshi Murakami, Mary J.C. Hendrix, Luigi Strizzi, David S. Salomon, Li Fu, Masaharu Seno. Characterization of cancer stem-like cells derived from mouse induced pluripotent stem cells transformed by tumor-derived exosomes/microvesicles. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3016. doi:10.1158/1538-7445.AM2014-3016