Abstract 255: Expressionprofiling of stem cell signaling alters with spheroid formation in CD133high/CD44high prostate cancer stem cells.
Authors: Oktem Gulperi , Bilir Ayhan , Uslu Ruchan , Inan Sevinc , Bakti Demiray Sirin , Atmaca Harika , Ayla Sule , Uysal Aysegul 
Published: August 2014

Introduction: Cancer stem cell (CSCs) theory provides new insight into the formation of tumors. Characterization of the pathways which regulate CSCs activity will facilitate the development of targeted therapies. Isolation of CSCs from multiple tumor types differentiate both in vivo and in vitro when cultured in serum, yet the factors responsible for their differentiation have not yet been identified. Current challenge is the enrichment of CSCs from established cell lines variety of solid tumors has been developed as three-dimensional (3D) cell culture. 3D spheroid model is a new technique for propagation of cells in-vitro using serum free medium and cultured low-adherence conditions and present a convenient model to investigate differentiating cancer cells. The objective of this study is to identify CD 133high/ CD44 high prostate CSCs and compare these profiles with non-sorting cells as bulk counterparts of the population. These two populations have been continued to be 3D multicellular spheroids and differentiation has been investigated with stem cell related genomic characteristics. Since CSCs are proliferate in a trice in tumor mass, our aim is to reveal the changes of cellular profile and heterogeneity of proliferated cells in 3D multicellular tumor spheroids.

Material and method: CSCs and non- CSCs were sorted with FACS and PCR array analysis of cell cycle regulation, embryonic and mesenchymal cell lineage related markers, TERT and Notch signaling were performed in both monolayer and spheroids. Immunohistochemistry of CD117, Notch1, Jagged1, Delta1, Sox2, C-myc, Oct4, KLF4, CD90 and SSEA1 were determined in groups.

Results and discussion: Most significant gene alteration observed CD 133high/ CD44 high population when in monolayer cells continued as spheroid. In this group remarkable up regulation was determined in Collagen type 9 alpha1 (COL9A1), Islet1 (ISL1) and Cyclin D2. Jagged1, DLL3 and Notch1 were respectively up-regulated genes in Notch signaling. According to immunoreactivity staining density of Jagged1, Sox2, Oct4 and Klf-4 increased significantly in sorting spheroids when compared non-sorting monolayer cells.

Conclusion: Isolated CSCs in human tumors could be altered their cellular characterization in the course of time and display a differentiation with maintaining their former surface antigens at a level of transcription or translation. In this study we have indicated this differentiation theory by using in-vitro 3D- spheroid model. It was observed that the cells alter their gene expression profiles during this process. Our hypothesis was supported by the observation that most significant gene alteration was in CD 133high/ CD44 high population when monolayer cells were allowed to grow as spheroid. In fact, this differentiation could be a principal mechanism which is responsible from malign process and tumor growth.

Citation Format: Gulperi Oktem, Ayhan Bilir, Ruchan Uslu, Sevinc Inan, Sirin Bakti Demiray, Harika Atmaca, Sule Ayla, Aysegul Uysal. Expressionprofiling of stem cell signaling alters with spheroid formation in CD133high/CD44high prostate cancer stem cells. [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 255. doi:10.1158/1538-7445.AM2013-255