JS-K, a Glutathione S-Transferase–Activated Nitric Oxide Donor With Antineoplastic Activity in Malignant Gliomas

Abstract

Background Glutathione S-transferases (GSTs) control multidrug-resistance and are upregulated in many cancers including malignant gliomas. The diazeniumdiolate JS-K generates nitric oxide (NO) on enzymatic activation by glutathione and GST, showing promising NO-based anticancer efficacy. Objective To evaluate the role of NO-based antitumor therapy with JS-K in U87 gliomas in vitro and in vivo. Methods U87 glioma cells and primary glioblastoma cell lines were exposed to JS-K and a variety of inhibitors to study cell death by necrosis, apoptosis and other mechanisms. GST-expression was evaluated by immunocytochemistry, PCR and Western blot and NO release from JS-K using a NO assay. The growth-inhibitory effect of JS-K was studied in a U87 xenograft model in vivo. Results Dose-dependent inhibition of cell proliferation was observed in human U87 glioma cells and primary glioblastoma cells in vitro. Cell death was partially induced by caspase-dependent apoptosis which could be blocked by Z-VAD-FMK and Q-VD-OPH. GST-inhibition by sulfasalazine, cGMP inhibition by ODQ and MEK 1/2 inhibition by UO126 attenuated the antiproliferative effect of JS-K, suggesting the involvement of various intracellular death signalling pathways. Response to JS-K correlated with mRNA and protein expression of GST and the amount of NO released by the glioma cells. Growth of U87 xenografts was significantly reduced, with immunohistochemical evidence for increased necrosis, apoptosis and reduced proliferation. Conclusion Our data for the first time show the potent antiproliferative effect of JS-K in gliomas in vitro and in vivo. These findings warrant further investigation of this novel NO-releasing prodrug in gliomas.

The nitric oxide donor JS-K sensitizes U87 glioma cells to repetitive irradiation

“…In contrast to our previous studies in orthotopic intracranial and flank-tumor rat models which demonstrated a moderate effect of NO donor compounds (JS-K, PABA/NO) on tumor growth, cell proliferation, survival, and tumor physiology, no significant in vivo antitumor effect could be observed in this orthotopic U87 xenograft mouse model. 13,14,38,39 Several facts might contribute to this result. First, in this study, JS-K was applied intravenously (i.v.)…”

“…The antitumor effect of JS-K could be confirmed in other glioma cell lines in vitro. 14,22,23 Multiple reasons underlie the strong therapy resistance of GBM cells: these include the accumulation of mutations that result in the increased expression of antiapoptotic and tumorigenic factors, deregulation or block of apoptosis inducing pathways, upregulation of enzymes essential for DNA repair, that is, O(6)-methylguanine-DNA methyltransferase (MGMT), or cell detoxification, as GSTs, and hypoxic conditions within the tumor area.…”

“…14 GST-dependent NO release from JS-K exerts a cytotoxic and antiproliferative effects in U87 cells in a timeand dose-dependent manner. 14,22 In contrast, irradiation has, if any, only mild effects on proliferation and cell viability in vitro. Combination of repetitive irradiation with JS-K concentrations up to 7.5 µM intensified and prolonged this inhibitory effect.…”

Controlled nitric oxide release for tissue repair and regeneration

“…, a site-specific NOreleasing compound that could be activated in glutathione (GSH)-expressing cells, showed improvement in duration time and treatment efficacy (Weyerbrock et al, 2012).…”

Expression of C-Terminal Modified Serine Palmitoyltransferase-1 Alters Chemosensitivity of Inflammation-Associated Human Cancer Cell Lines

“…Similar to excess Glutamate, SAS targets the antioxidant xCT-system and the resulting pharmacologic effect is reported to improve antitumor efficacy of COX inhibitors in in vivo models of tumorigenesis [51] [52]. As a clinically approved xCT inhibitor [53], SAS is reported to inhibit GSH formation or the activation of AKT and focal adhesion kinases [54] [55]. SAS has been used as an effective inhibitor of tumor growth and tumor-associated seizures, particularly for the inflammatory brain tumor [56].…”