Basic Issues on Cancer Stem Cells-Concept, In vitro Models and Therapeutic Implications

Over the last decade, the concept that tumors are maintained by their own stem cells, termed cancer stem cells, has created great interest. Cancer stem cells (CSCs) appear to be the source of all the cells in the cancers which they cause. They seem to be closely related to and may often originate with adult stem cells. CSCs can renew themselves, so they are able to slumber for prolonged periods of time and to colonize other parts of the body. The most striking importance of CSCs is their role concerning remission and recurrence in patients with various cancers. Current cancer treatments selectively attack rapidly growing cells. They are effective against the bulk of the tumor mass, but these drugs are also cytotoxic to normal healthy cells. CSCs may be especially resistant to eradication because stem cells have a tendency to divide at a slow rate. Therapeutic modalities which target these cells would improve the outcome of cancer patients. Recent researches concerning CSCs are highly substantial in the oncology era. We review the concept of CSCs, in vitro models and the therapeutic implications of the stem cell model of cancer