Table 2.
Molecular and functional heterogeneity of BCSCs
| Molecular signature | Significance/properties | References |
|---|---|---|
| ALDH1+ | High tumorigenic potential | 101 |
| Epithelial-like, proliferative | ||
| Expression of MET genes | ||
| Located in tumor interior | ||
| EpCAM+/ALDH1+/HER2+/EGFR+/HPSE+/Notch1+ | Brain metastasis | 104 |
| High expression levels of vimentin and keratins 8 and 18 | ||
| No detectable levels of keratins 19 and 20 | ||
| Expression of the stem cell phenotype CD44+/CD24low | ||
| ALDH1+/CD44+/CD24− | Very high tumorigenic potential, rare | 13, 101 |
| CD44+/CD24− | High tumorigenic potential | 101, 102 |
| Mesenchymal-like, quiescent | ||
| Expression of EMT genes | ||
| Located in tumor periphery | ||
| CD44+/CD24low | High tumorigenic potential | 102 |
| Epithelial-like | ||
| Expression of keratins 5/6 | ||
| Low expression of vimentin, keratin 17, and E-cadherin | ||
| CD44−/CD24+ | Bone tropism | 105 |
| Expression of low molecular weight keratins, EMA, and vimentin | ||
| Bone tropism signature (88 upregulated and 22 downregulated genes) | ||
| ER−/CD44+/CD49fhi/CD133 | High tumorigenic potential | 103 |
| High levels of keratins 18 and 14 | ||
| EpCAM+CD44+CD47+MET+ | Escaping immune response | 35 |
| Critical in bone, lung, and liver metastases | ||
| Associated with disease progression |
Abbreviations: ALDH1, aldehyde dehydrogenase 1; BCSC, breast cancer stem cell; EMA, epithelial membrane antigen; EGFR, epidermal growth factor receptor; EMT, epithelial-to-mesenchymal transition; EpCAM, epithelial cell adhesion molecule; ER, estrogen receptor; HER2, human epidermal growth factor receptor 2; HPSE, heparanase MET, mesenchymal-to-epithelial transition.