Impairment of Glioma Stem Cell Survival and Growth by a Novel Inhibitor for Survivin–Ran Protein Complex

Abstract

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.

Effective Targeting of the Survivin Dimerization Interface with Small-Molecule Inhibitors

“…To verify that LQZ-7 indeed binds to survivin and inhibits survivin dimerization, we took advantage of the intrinsic fluorescent property of LQZ-7 and performed a fluorogenic titration assay in the presence or absence of survivin as previously described (39). Figure 2F shows that the intrinsic fluorescence of LQZ-7 dramatically increases in the presence of recombinant survivin, indicating that LQZ-7 likely interacts with survivin.…”

“…LLP3 was thought to bind to the dimerization interface of survivin (39). However, LLP3 had no effect on survivin dimerization or its expression.…”

“…Fluorogenic assay was performed as previously described (39). Briefly, LQZ-7 was preincubated without or with 10 mg purified survivin for 30 minutes at 37 C followed by determination of fluorescence emission at 485 nm with excitation at 590 nm.…”

Integrin α5β1 and p53 convergent pathways in the control of anti-apoptotic proteins PEA-15 and survivin in high-grade glioma

“…49,50 Survivin participates to glioma radio-and chemotherapy resistance [50][51][52] and a selective inhibitor of survivin, YM155, is currently under clinical trials. [53][54][55] Beside the p53-dependent transcriptional control of survivin, other pathways including the PI3K/AKT or the integrin-linked kinase pathway driven by tyrosine kinase receptors or integrins 51,50,56 have been implicated in its regulation. Survivin is thus confirmed as a pertinent therapeutic target in GBM and strategies aiming to decrease its expression should be considered.…”

Mesenchymal glioma stem cells are maintained by activated glycolytic metabolism involving aldehyde dehydrogenase 1A3

“…The unique properties of GSCs are considered to contribute to the therapeutic resistance of HGG (8,9). Thus, understanding and targeting tumor-propagating GSCs could be beneficial in developing effective strategies that overcome therapeutic resistance of HGG.…”