Dlxin-1, a member of MAGE family, inhibits cell proliferation, invasion and tumorigenicity of glioma stem cells

We have previously reported the presence of Dlxin-1, a member of the melanoma antigen gene (MAGE) family, in the brain and showed its function as a cell cycle arrest protein, suggesting that Dlxin-1 may have anti-proliferative functions in rapidly growing tumors. Using the cancer stem cell hypothesis, which attributes the initiation and progression of brain tumors to the cancer-initiating stem cells, we have investigated the role of Dlxin-1 in the glioma stem cells propagated by us as a cell culture system comprising of HNGC-2 cells. Our studies provide evidence about the role of Dlxin-1 as an anti-tumorigenic protein in the highly chemo-resistant glioma stem cells. Next, we show that these anti-proliferative effects are manifested by Dlxin-1 through down regulation of the activities of MMP-2 and MMP-9, and through interaction of Dlxin-1 with its target protein P311 that is involved in glioma cell invasion. In summary, we establish the roles for Dlxin-1, one as an anti-tumorigenic and anti-invasive protein in high-grade gliomas and the other as an inducer of differentiation of glioma stem cells. These two attributes, in conjunction, result in conversion of the drug-resistant brain tumor stem cells to the tumor-attenuated cells that may now be more amenable to effective therapeutic targeting. Cancer Gene Therapy (2011) 18, 206-218; doi: 10.1038/cgt.2010.71; published online 26 November 2010