Characterization of proteins involved in intracellular pathways distinctive for colon cancer stem cells

The aim of this thesis is to use a differential proteomic approach to study protein expression changes (up- or down- regulation) in colon cancer stem cells (CD133+ cells) compared to colon cancer differentiated cells (CD133- cells), isolated from a colorectal carcinoma cell line. This comparison was performed through the use of the 2D-DIGE methodology (Yan et al., 2002; Alban et al., 2003). In particular we analyzed protein expression in a colon cancer cell line Caco-2 available at CEINGE cell bank. CSCs have been separated from differentiated cancer cells by flow cytometry using CD133 as stemness marker.
Expanding evidence highlights the role of CD133 as a marker of CSCs in various human tumours. CD133 was expressed in combination with CD44+ in approximately 0.1% of cells within a large series of prostate tumours, irrespective of their grade or metastatic state. These cells were capable of selfrenewal, proliferation, and multi-lineage differentiation in vitro to recapitulate the original tumour phenotype, consistent with CSC properties (Collins et al., 2005). In fact, CSCs are significantly enriched in CD133+ subpopulations derived from human colon cancer and hepatocellular carcinomas, as shown by their potential to both self-renew and differentiate, to form colonies and proliferate in vitro, and by their ability to reform the original tumour phenotype when transplanted either subcutaneously or into the renal capsule of immunodeficient mice (O’Brien et al., 2007; Suetsugu et al., 2006).