Cancer stem cells and intrinsic subtypes in bladder cancer

Recent studies indicate that bladder cancers contain tumorigenic subpopulations known as cancer stem cells, which probably also mediate recurrence and progression. They express biomarkers (including cytokeratins and cell surface markers) that subcategorize bladder cancers into intrinsic basal and luminal subtypes. Basal tumors are characterized by especially high levels of basal cytokeratins and biomarkers of epithelial-to-mesenchymal transition (EMT) which are implicated in modulating “stemness”, circulating tumor cell (CTC) production, and metastasis. Although luminal cancers appear to be less intrinsically aggressive, contact with the extracellular matrix may allow them also to produce cells with basal/stem cell features at their leading edges, endowing them with the capacity for invasion and CTC production and metastatic potential. The implications of cancer stem cells and the intrinsic subtypes for prognostication and therapy are discussed in this chapter.