Cancer Stem Cells: Metastasis and Evasion From the Host Immune Responses

Metastasis is the leading cause of cancer-related deaths. Cancer stem cells (CSCs) have the distinct ability of self-renewal and proposed capacity to metastasize to distant locations. CSCs are more resistant to radiation and chemotherapeutic agents compared to other cancer cells and, therefore, survive conventional therapies, resulting in local and distant relapse of the disease. This chapter reviews the current knowledge of the metastatic potential of CSCs, termed as metastatic CSCs (MCSCs). Limited evidence has also led to the hypothesis that CSCs may evade host immune responses. This chapter describes the immunosuppressive approaches that cancer cells, including CSCs and MCSCs, employ to evade the host immune system. In addition, the types of immune and inflammatory cells that may be utilized to support tumor progression and promote metastasis are illustrated. Understanding these mechanisms may provide new insights and aid in the development of novel strategies to target the “Achilles’ heel” of CSCs and MCSCs.