Targeting Cancer Stem Cells: New Perspectives for a Cure to Cancer

Cancer stem cells (CSCs) are present in many solid tumors. Their signaling pathways and functions may be the key to developing new anticancer strategies against cancer. Several studies have linked the signaling pathways’ (e.g., Wnt, Notch, and Hedgehog pathways) aberrant activation to the development of numerous cancers. These signaling pathways hence provide attractive targets for further study toward new therapies. CSCs show several characteristics, such as self-renewal, differentiation, high tumorigenicity, and resistance to anticancer drugs. Drug resistance is the most useful in further evaluating the possibilities of reducing tumor mass or eliminating cancer by discovering new therapies. One of the key questions concerns the necessity of identifying superficial as well as intracellular markers, which are essential if the drug is to respond positively to CSCs. In recent years, CD133, CD44, ABCG2, and ALDH have been identified as biomarkers for certain forms of CSCs. However, recent studies have contributed to a better understanding of CSC-specific antigens; to date, there is no univocal characterization of antigens for CSCs. Our chapter aims to highlight the importance of identifying new markers to develop new therapeutic strategies against cancer.