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CancerQuest > Introduction to Cancer Biology > Introduction to How Cancer Begins > What are Cancer Stem Cells > The Search for Cancer Stem Cells

The Search for Cancer Stem Cells

What led to the search for cancer stem cells?

There are several reasons why many researchers find the cancer stem cell hypothesis appealing. Cancer stem cells provide one possible explanation for the frequent failure of cancer treatments, the large amount of cells needed to cause cancer growth in model organisms, and gaps in other theories of cancer development. A large challenge has been the identification and isolation of cancer stem cells. Researchers have identified some cell surface proteins (also called markers) found on cancer cells that have some important stem cell capabilities. These markers include CD44, CD133, and ALDH1.⁽¹⁾

One of the pieces of evidence that favors the existence of cancer stem cells is the fact that when researchers look at tumors they appear to contain several differentiated cell types. The traditional theory on the development of cancer is able to explain this, but the large number of mutations necessary to create the mixture is unlikely. An illustration,- if tumors form from a single mutated cell the tumor would only contain cells of that type rather than cells of many types:

If multiple cells of different types in the same area have mutations this would lead to a tumor of mixed cell types:

Cancer stem cells have the ability to produce cells of many different types creating the mixture of cells found in a tumor:

The possibility of a stem cell becoming a cancer stem cell is, statistically, more likely to happen than multiple mutations in multiple cells in the same area in order to produce a tumor with multiple cell types.^{(2) (1)}

References for this page:

1. Boman BM, Wicha MS. "Cancer Stem Cells: A Step Toward the Cure" Journal of Clinical Oncology. 2008 Jun 10;26(17):2795-9. [PUBMED]
2. Lee CJ, Dosch J, Simeone DM. "Pancreatic Cancer Stem Cells." Journal of Clinical Oncology (2008); 26(17):2806-12 [PUBMED]