Impairment of glioma stem cell survival and growth by a novel inhibitor for Survivin-Ran protein complex

Purpose: Glioblastoma multiforme (GBM) is a devastating disease. Recent studies suggest that the stem cell properties of GBM contribute to the development of therapy resistance.

Experimental design: The expression of Survivin and Ran was evaluated by immunohistochemistry with GBM tissues, and quantitative Reverse Transcriptase (qRT)-PCR and immunocytochemistry with patient-derived GBM sphere cultures. With a computational structure-based drug design, 11 small-molecule compounds were designed, synthesized, and evaluated as inhibitor candidates for the molecular interaction of Survivin protein. The molecular mechanism of the lead compound, LLP-3, was determined by Western blot, ELISA, in situ proximity ligation assay, and immunocytochemistry. The effects of LLP-3 treatment on GSCs were evaluated both in vitro and in vivo. Quantitative immunohistochemistry was carried out to compare Survivin expression in tissues from 44 newly diagnosed and 31 recurrent post-chemoradiation GBM patients. Lastly, the sensitivities of temozolomide-resistant GBM spheres to LLP-3 were evaluated in vitro.

Results: Survivin and Ran were strongly expressed in GBM tissues, particularly in the perivasculature, and also in patient-derived GSC cultures. LLP-3 treatment disrupted the Survivin-Ran protein complex in Cancer cells and abolished the growth of patient-derived GBM spheres in vitro and in vivo. This inhibition was dependent on Caspase activity and associated with p53 status of cells. Immunohistochemistry showed that Survivin expression is significantly increased in recurrent GBM compared with newly diagnosed tumors, and temozolomide-resistant GBM spheres exhibited high sensitivities to LLP-3 treatment.

Conclusions: Disruption of the Survivin-Ran complex by LLP-3 abolishes survival and growth of GSCs both in vitro and in vivo, indicating an attractive novel therapeutic approach for GBM.