Figure 2.

Simplified “Unifying Hypothesis” on origin of CSC, its role in tumor progression and metastasis. (a) CSC formation- mutation in normal stem, progenitor, or differentiated cell will activate self-renewal genes to form CSC. Accumulating evidence suggests the importance of “CSC niche” and its interdependence with CSCs. A “CSC Niche” will consist of plethora of molecules and cells like stem cells, surrounding differentiated cells, stromal support cells, inflammatory cells, soluble factors, extracellular matrix, and blood vessels. (b) Tumor progression—according to “Cancer Stem Cell Hypothesis” CSCs have the capacity to undergo self-renewal and have the potential to differentiate into different types of cells in a specific lineage. This accounts for heterogeneity and progression of tumor. (c) tumor metastasis—specialized stem cells described under the concept of “Migrating cancer stem (MCS)-cells” along with cancer angiogenesis play important role in tumor metastasis. MCS-cells disseminate through various portals like blood vessels to various distant organs/tissues which provide favorable environment for the growth and division of these migrated cells.