Fig. 1.

The characteristics of cancer stem cells. Due to the resistance of CSCs to conventional treatment, the majority of tumor patients have recurrent and metastatic disease after receiving conventional antitumor therapy. In vitro, a single CSC possesses the capability to form tumor spheroids, which represent the self-renew and proliferation ability of CSCs. In vivo, a small number of cancer stem-like cells can trigger tumor forming in mice. In addition, CSCs have inherent drug resistance and dormancy characteristics, as well as the ability to trigger distant metastasis of cancer