How do tumor stem cells actively escape from host immunosurveillance?

Tumor stem cells (TSCs) are considered as the "seeds" in tumor development, metastasis and recurrence. Despite the various immunosurveillance mechanisms in the host, TSCs may possess the phenotypic and functional properties to evade host immunosurveillance and immune-mediated rejection in immunologically intact individuals. The mechanisms of TSC recognition and their consequent destruction are actively disturbed by various processes, including altered immunogenicity of TSCs, production of TSC-derived regulatory molecules, and interaction of TSCs with tumor-infiltrating immune cells. In addition to these TSC-mediated mechanisms, the diverse mesenchymal cells and cytokines in the tumor microenvironment are contribute to TSC immune escape. Recent mechanistic studies provide a more comprehensive understanding of TSCs in the biology, prevention, and therapy of solid tumors. This review will focus on the latest findings for mechanisms underlying TSCs' escape from the attack of immune system.