Markers in normal and cancer stem cells.

In an effort to better understand and address the challenges of cancer research and treatment, a new model of tumorigenesis is being developed - the cancer stem cell model. Building upon traditional concepts of cancer and stem cells, this model is intended to shed new light on the continued struggle with treatment issues such as tumor drug-resistance and recurrence. This review describes the cancer stem cell model with an emphasis on markers that represent the "stemness" phenotype. A thorough understanding of normal and cancer stem cells is necessary for a precise delineation of cancer stem cells. The objective of such an improved delineation is to develop targeted therapy for selective elimination of cancer stem cells with minimal toxicity to normal stem cells. Specific targeting of cancer stem cells has proved to be a significant challenge due to the commonality of many markers between normal and cancer stem cells. However, research in the area of cancer biomarkers is slowly, but steadily, progressing.