Tumor heterogeneity of gastric cancer: From the perspective of tumor-initiating cell

Table 1 Putative cell surface markers of gastric tumor-initiating cell

Putative marker	Tumor sphere formation (in vitro)	Tumor formation during serial engraftment (in vivo)	Limiting dilution assay	Chemo-resistance	Others	Ref.
CD44	+	+	Not conducted	+	(1) Capacity of cell differentiation (2) Giving rise to both CD44+ and CD44- GC cells (3) Independent prognostic factor of GC patients	Takaishi et al[29] Yoon et al[119]
CD44/CD24	+	+	+	Not conducted	Capacity of cell differentiation	Zhang et al[32]
CD44/CD54	+	+	+	Not conducted	(1) Capacity of cell differentiation (2) Detectable from peripheral blood	Chen et al[33]
CD44/CD26	+	+	Not conducted	+	/	Nishikawa et al[127]
CD44/EpCam	+	+	+	+	(1) Capacity of cell differentiation (2) Restoration of histological heterogeneity from single CD44/EpCam+ cell	Han et al[31]
CD44v810/EpCAM	+	+	+	+	CD44v8-10 but not CD44 standard increase the frequency of tumor initiation	Lau et al[30]
CD90	+	+	+	+	Restoration of cellular hierarchy from single CD90+ cell	Jiang et al[35]
CD133	+	+	Not conducted	+	Independent prognostic factor of GC patients	Zhang et al[128]
Lgr5	+	+	Not conducted	Not conducted	/	Wang et al[40]
ALDH	+	+	+	+	/	Nishikawa et al[42]
ALDH1/REG4						Katsuno et al[45]
Oct4/Sox2/Nanog	+	+	Not conducted	+	Independent prognostic factor of GC patients	Liu et al[129]

ALDH: Aldehyde dehydrogenase; GC: Gastric cancer.