Roles of cancer stem cells in cancer immune surveillance

The interaction between cancer cells and the immune system has been studied for more than 130 years; however, how to strengthen the immune system and suppress cancer cells remains unclear. All publications related to cancer immune surveillance were collected based on the keywords "cancer immune surveillance" and "stem cell" in the PubMed, Web of Science and Scopus databases. In the last few decades, researchers have found that cancer stem cells -a subpopulation of cancer cells -are involved in the initiation, progression, metastasis, and recurrence of various types of cancer. With mutation and evolution, cancer cells can escape immune surveillance. Several mechanisms underlying this phenomenon have been discovered, including influencing the antigen processing and presentation machinery, increasing the expression of immune-controlling molecules, or taking advantage of the regulatory mechanisms of the immune system itself. However, the roles of cancer stem cells in these mechanisms are unknown. In this review, we summarize the mechanisms of immune-related molecules across cancer cells and the roles of cancer stem cells in immune surveillance.