Presence and role of stem cells in ovarian cancer

Table 1 Putative ovarian cancer stem cell markers and their relevance.

Marker	Type of protein	Suspected role in cancer stem cells
CD24	Cell surface transmembrane glycoprotein	Stem gene expression[118,119], tumor formation[73,74], metastasis[75,76], chemoresistance[75], poor prognosis[75,77], recurrence of disease[77]
CD44	Cell surface transmembrane glycoprotein	Tumor formation[78], progression[79], chemoresistance[78], poor prognoses[80], recurrence of disease[81]
CD117	Tyrosine kinase receptor	Tumor formation[65,66,120,121], chemoresistance[66,122], poor prognosis of disease[65,67]
CD133	Cell surface transmembrane glycoprotein	Tumor formation[68], progression[69], chemoresistance[70,71], poor prognosis[71], successful treatment[72]
EpCAM	Cell surface transmembrane glycoprotein	Tumor growth inhibition[123], poor survival and chemoresistance[124]
ROR1	Tyrosine kinase receptor	Spheroid and tumor formation[125], poor prognosis[126]
ALDH	Cytosolic aldehyde dehydrogenase enzyme	Cell proliferation and migration promotion[82], poor survival[83,85], chemoresistance[83-85]
SOX2	Transcription factor	(Cancer) stem cell maintenance and self-renewal[86,87], poor prognosis and chemoresistance[88]
OCT4	Transcription factor	(Cancer) stem cell maintenance and self-renewal[86,87], tumor formation and drug resistance[89]
NANOG	Transcription factor	(Cancer) stem cell maintenance and self-renewal[86,87], poor prognosis[90-92], chemoresistance[91,93]
MYC	Transcription factor	Tumor formation[94], chemoresistance[95]
ABCB1, ABCG2	ATP binding cassette transporter	Chemoresistance[96-99]

CD24: Cluster of differentiation 24; CD44: Cluster of differentiation 44; CD117: Cluster of differentiation 117; CD133: Cluster of differentiation 133; EpCAM: Epithelial cell adhesion molecule; ROR1: Receptor tyrosine kinase-like orphan receptor 1; ALDH: Aldehyde dehydrogenase enzyme; SOX2: SRY-box 2; OCT4: Octamer-binding protein 4; NANOG: Homeobox protein NANOG; MYC: Transcription factor encoded by myelocytomatosis viral oncogene; ABCB1: ATP binding cassette transporter sub-family B member 1; ABCG2: ATP-binding cassette sub-family G member 2.