Stemness markers of osteosarcoma

Osteosarcomas (OSs) are a heterogeneous group of rare tumors that affect children and adolescents between 10 and 25 years, and have a second peak of incidence in the elderly, where they are associated with defective bone remodeling. Most OSs are of high grade and frequently develop pulmonary metastases. OSs derived from progenitor cells that have accumulated mutations leading to high proliferation and defects in their ability to differentiate in osteoblasts. A growing body of evidence supports the hypothesis that only a small subset of cells within a tumor, called cancer stem cells (CSCs), is capable to initiate a new tumor and sustain its growth. CSCs share many features with normal stem cells, such as self-renewal, differentiation, proliferation potential, drug resistance and migration capacity. In this chapter, we present current knowledge about the biology of osteosarcoma stem cells, highlighting on markers that are implicated in their detection and selection. Improved understanding into the cell origins of osteosarcomas and further refinements in the molecular characterization of OSs will be essential in the discrimination of putative CSCs. In addition, more defined criteria for the definition of putative stem cells identified via the various assays will be paramount to any progress achieved in the study of stem cell biology. In the future, hopefully, the unequivocal identification of osteosarcoma CSCs coupled with the development of drugs targeting CSCs may lead to new view of cancer and above all to eradicate itself.