fig1

Figure 1. The role of glioma stem cells (GSCs) in tumorigenesis. The heterogeneous nature of glioblastoma (GBM) tumors creates an opportunity for the evolutionary selection of particular clonal cell populations with growth advantages and propagates advantageous mutations. In particular, a small population of quiescent cells with stem-like properties, GSCs, has been shown to be particularly resistant to temozolomide treatment in GBM and these cells are thought to act as the recurrent tumor-initiating cells, which are responsible for regrowth of tumors after initial treatment. While the criteria for defining GSCs are still evolving, the most commonly used markers for GSCs include CD133+, CD44+, CD15+, CD70+, S100A4, ALDH1A3, Nanog, SOX-2, and Nestin. These stem cell characteristics are enhanced by many of the molecular mechanisms of temozolomide resistance in GBM as well as being intrinsic drivers of resistance. Modified from Xie et al.^[28]