Lentiviral transfer of an inducible transgene expressing a soluble form of Gas1 causes glioma cell arrest, apoptosis and inhibits tumor growth

Gliomas are the most frequent primary tumors of the central nervous system, and their clinical prognosis remains very poor. Because of the characteristics of gliomas, gene therapy appears as a potentially relevant strategy for their treatment. However, the inability of viral vectors to transfer the therapeutic genes to a significantly high number of tumor cells, due to their limited diffusion and distribution, remains a critical obstacle for their application treating gliomas. We have demonstrated that the overexpression of growth arrest specific1 (Gas1) induces cell arrest and apoptosis and eliminates glioma cells in vitro and when implanted in mice. To improve the therapeutic range of Gas1, we generated lentiviral vectors coding for a soluble form of Gas1. Here, we show that cells infected with this virus produce the mutant protein, that acting both in autocrine and paracrine manners, causes death of infected and neighbor cells, thus importantly enhancing the effect of Gas1. Furthermore, the administration of this vector, or cells expressing it, inhibit the growth of tumors inoculated in mice. We present a gene therapy strategy that increases the effect of the therapeutic molecule by eliminating not just the infected cells that express Gas1, but neighbor non-infected cells. Cancer Gene Therapy (2011) 18, 87-99; doi: 10.1038/cgt.2010.54; published online 1 October 2010