Tumor type (%) of sp cells Cellular phenotype and features of sp cells Ref. Breast 0.18 ± 0.45% CD44+/CD24−/vimentin higher and lower levels of cytokeratins compared to non-SP cells. [53 ] [54 ] Lung adenocarcinoma 24% SP cells showed chemoresistance to platinum drugs and high expression of genes related to drug resistance (AKR1C1/C2 and NR0B1) or cancer metastasis (TM4SF1) & high mRNA expression of ABCG2, ABCC2. [55 ] Endometrial cancer 0.02% Higher expression levels of vimentin, alpha-smooth muscle actin, and collagen III in SP induced tumors. [56 , 57 ] Ewing’s sarcoma 1.2% High clonogenicity, invasiveness, and ABC transporter expression in SP cells than non-SP [58 ] Glioblastoma 0.4–1.5% CD133+ SP cells coexpressed nestin and generated tumors in brains of NOD/SCID mice. [59 ] Prostate cancer 0.1–0.9% CD133+, CD45−, CD81+, Sca-1+ [60 ] Pancreatic cancer 2.1–8.7% CD133+ SP cells showed significant levels of mRNA expression for CD133, ABCG2, and Notch1 than non-SP cells. [61 ] Leukemia 0.008–4.1% CD34(+) CD38(−) CD123+ [62 ] Hepatocellular carcinoma 0.1–28.7% SP cells showed high chemoresistance, self-renewal, clonogenicity, and ABCG2 expression. [63 ] Medulloblastoma 12.4–39.1% CD133+ SP cells with increased cell size, decreased S-phase, and proliferative capacity. [64 ] Renal epithelial malignancy 5.9 ± 0.9% SP enriched for quiescent cells with high proliferative capacity and stem-like properties. [65 ] Head & neck squamous Carcinoma 0.69–0.9% Activation of EGFR, a gene implicated in HNSCC tumorigenesis [32 ] Urological malignancy 0.1–0.6% SP fraction has enhanced colony forming and proliferative capacity. [66 ] Ovarian cancer 0.9% SP cells showed higher levels of Oct3/4 and colony formation efficiency than non-SP cells. [67 ] Nasopharyngeal carcinoma 2.6% CK19 highly expressed SP cells were more chemo/radiation resistant related to the expression of ABCG2/smoothened protein. [68 ] Melanoma 0.96% CD44+/CD133+/CD24+/ABCG2 high SP cells. [69 ] Laryngeal cancer 1.7–17% SP cells had high self-renewal, proliferation, radiation resistance, and tumorigenicity. [70 ] Gastric cancer 0.001–12% High expression levels of adhesion molecules
2,
5,
3 and
5 integrins, CD44, Oct3/4, and Sox2 in SP cell-injected tumors. [71 ]
