Table 2.

Ovarian cancer stem cells and drug resistance mechanisms.

Marker/Protein	Suggested Drug Resistance Mechanism(s)	References
CD44, a cell surface receptor, an integral membrane glycoprotein that binds several ECM components, including hyaluronan	Activation of NF-κB signaling pathway and the production of various cytokines	[44,58,59]
CD117 (c-Kit), a type III tyrosine kinase receptor	Activation of PI3K/AKT and Wnt/β-catenin signaling pathway and increased expression of ABC transporters.	[44,47,60,61]
ABC transporters	ABC transporters pump out of the cell various chemotherapies.	[44,47,60]
ALDH, aldehyde dehydrogenase	Enhanced drug metabolism.	[44,47,61,62]
CD133, a member of the pentaspan transmembrane protein family	Expression of ID1 proteins transcriptional regulators.	[44,57,63,64]
Bcl-xL, BCL-2 protein family	Inhibition of the activation of the BAX and BAK pro-apoptotic proteins.	[47,65]