Stemness in Cancer: Stem Cells, Cancer Stem Cells, and Their Microenvironment
Table 2
Comparison of traits of normal Stem Cells and Cancer Stem Cell (CSCs) niches.
Trait
Normal Stem Cells
Cancer Stem Cells
Niche element: mesenchymal cells
Contribute with nutritional and stem-cell-fate factors [82]
Tumors educate the surrounding cells to provide nutrients, although highly resistant to lack of nutrients [83, 84]
Niche element: immune system cells
Modulate local environment for immune protection of SCs (immune suppression = immune-sanctuaries) [85]
Modulate local environment for immune protection of CSCs (immune suppression = immune-sanctuaries) [86]
Niche element: extracellular matrix
The matrix signals to SCs for fate regulation, promoting stemness and physiological maintenance [87]
Cancers cells produce large quantities of metalloproteinases, enzymes that degrade and remodel the ECM, thus promoting invasion and tumor angiogenesis [88]
Highly resistant to lack of oxygen [91], common in specific regions of tumors
Resistance to environmental stress
Highly resistant to cell death by noxious agents [92]
Highly resistant to lack of nutrients. Highly resistant to cell death by chemotherapy agents. Multidrug Resistance (MDR) pumps that extrude toxic compounds ATP-binding cassettes transporters (abc) [93] Quiescence activation through the ability to perceive stress [12, 24]