Figure 2.

Autophagy in CSCs. (A) Autophagy plays an important role in maintaining both normal tissue stem cells and CSCs. The survival and quiescence of normal tissue stem cells appears dependent on autophagy and autophagy has also been reported to promote pluripotency. In CSCs, autophagy promotes expression of stem cell markers such as CD44 as well as expression of mesenchymal markers such as vimentin. Autophagy also promotes spheroid formation, in vivo tumorigenesis and drug resistance consistent with a critical role in maintaining CSCs. Inhibition of autophagy limits tumor dormancy and promotes outgrowth of metastases. (B) Key transcription factors have been linked to the induction of autophagy and the stem cell state, including FOXO3A, which induces expression of autophagy genes in stem cells and is itself turned over by autophagy. Also, SOX2 and STAT3 have been shown to modulate autophagy genes and to determine the stemness of CSCs.