Table 1 Reports of expression/functional profiles recently found to identify putative human nasopharyngeal cancer stem-like cells

Label-retaining cells

5-8 F, 6-10B and TMNE

Increased clonogenicity, tumor formation in mice at low titers [16, 17]

Label-retaining cells (PKH26⁺)

CNE1, CNE2, SUNE1, and HONE1

Longevity, sphere formation, side population cells, and resistance to radiotherapy [18]

Side population cells

CNE-2

Strong tumorigenesis ability, more resistant to chemotherapy and radiotherapy, cytokine 19 positive [24]

Side population cells (ABCG2⁺)

5-8 F

ABCG2 alone is not sufficient, PSCA, ABCG2 and ALP were expressed in ABCG2⁺ cells, and K19, integrin α6, integrin β4, CD44 and K14 were expressed in ABCG2⁻ cells [25]

ALDH1^high cells or ALDH1A1

5-8 F and CNE2

High ALDH1 activity, higher clone formation efficiency, differentiation capability and higher migration, enhanced capacities of growth, proliferation, and tumorigenesis,5 to 10³ ALDH1^high NPC cells required to induce tumors, vimentin⁺, and E-cadherin⁻,OCT4, SOX2 and Nanog⁺[27, 28]

C666-1

Significantly greater ability to proliferate, be clonogenic, resist chemotherapy drugs and radiation, and express pluripotent markers, tumor formation at a higher rate [29–31]

CD44⁺

5-8 F, C666-1

Higher survival rate, resist chemotherapy drugs [35, 36]

CD133⁺

CNE2 and primarily cultured NPC cells

Nanog⁺ and Sox2⁺, a strong potential for self-renewal, sphere formation, proliferation and differentiation and a greater potential for in vivo tumor formation in nude mice [39]

Sphere-forming cells

C666-1

CD44⁺ and SOX2⁺, higher spheroid formation efficiency, resistant to chemotherapeutic agents, CCR7⁺ associated recurrent disease and distant metastasis [48]