Role of Cancer Stem Cells of Breast, Colon, and Melanoma Tumors in the Response to Antitumor Therapy

Abstract

Solid tumors represent the major cancer burden, and epithelial cancers arising in tissues that include breast, colon and skin constitute the most common forms of all cancers and display extraordinarily high mortality rates in industrialized countries. Recent data suggest that cancers arise from rare self-renewing stem cells that are biologically distinct from their more numerous differentiated progeny. Growing evidence suggests that pathways regulating normal stem cell self-renewal and differentiation are also present in cancer cells and cancer stem cells (CSCs) in solid tumors. A small number of cells identified as CSCs from solid tumors usually express organ-specific markers, contribute to chemotherapy resistance and are able to generate a new tumor in immunodeficient mice. Although in recent years the knowledge of the biology of CSCs in these tumors has increased, however, we are not yet able to clearly distinguish between the characteristics of those with compared with non-tumor stem cells, or even to set up a CSCs methodology of isolation. It becomes necessary, therefore, further evaluation of CSCs biomarkers and a better understanding of signaling pathways that support stem cell renewal in normal and malignant tissue. Actually, the isolation and characterization of CSCs in breast, colon and melanoma tumor is providing a great aid in the diagnosis, prediction of prognosis and response to chemotherapy. Moreover, the discovery and development of specific therapies that target CSCs has the potential to revolutionize the treatment of these tumors.