Recent studies have suggested the existence of a small subset of
cancer cells called cancer stem cells (CSCs), which possess the ability to initiate
malignancies, promote
tumor formation, drive
metastasis, and evade conventional
chemotherapies. Elucidation of the specific signaling pathway and mechanism underlying the action of CSCs might improve the efficacy of
cancer treatments. In this study, we analyzed differentially expressed
proteins between
glioma stem cells and differentiated
tumor cells isolated from the human
glioma cell line, U251, via iTRAQ-tagging combined with two dimensional liquid chromatography tandem MS analysis to identify
proteins correlated with specific features of CSCs. Out of a total data set of 559 identified
proteins, 29
proteins were up-regulated in the
glioma stem cells when compared with the differentiated cells. Interestingly, The expression level of S100A9 was fivefold higher in
glioma stem cells than differentiated cells. Similar results were also observed in
glioma stem cells derived from other
glioma cells. More importantly, knockdown of S100A9 by RNA interference suppressed the proliferation of
glioma stem cell line and decreased the growth of xenograft
tumors in vivo. Taken together, these results indicate that the
tumorigenesis potential of CSCs arises from highly expressed S100A9.