MCT4 Promotes Tumor Malignancy in F98 Glioma Cells

Monocarboxylate transporter 4 (MCT4, SLC16A3) is elevated under hypoxic conditions in many malignant tumors including gliomas. Moreover, MCT4 expression is associated with shorter overall survival. However, the functional consequences of MCT4 expression on the distinct hallmarks of cancer have not yet been explored at the cellular level. Here, we investigated the impact of MCT4 overexpression on proliferation, survival, cell death, migration, invasion, and angiogenesis in F98 glioma cells. Stable F98 glioma cell lines with MCT4 overexpression, normal expression, and knockdown were generated. Distinct hallmarks of cancer were examined using in silico analysis, various in vitro cell culture assays, and ex vivo organotypic rat brain slice culture model. Consistent with its function as lactate and proton exporter, MCT4 expression levels correlated inversely with extracellular pH and proportionally with extracellular lactate concentrations. Our results further indicate that MCT4 promotes proliferation and survival by altered cell cycle regulation and cell death mechanisms. Moreover, MCT4 overexpression enhances cell migration and invasiveness via reorganization of the actin cytoskeleton. Finally, MCT4 inhibition mitigates the induction of angiogenesis, suggesting that MCT4 also plays a crucial role in tumor-related angiogenesis. In summary, our data highlight MCT4/SLC16A3 as a key gene for distinct hallmarks of tumor malignancy in glioma cells.

Association of decreased levels of lipopolysaccharide-binding protein with OKN-007–induced regression of tumor growth in an F98 rat glioma model

OBJECTIVEHigh-grade gliomas, such as glioblastoma (GBM), are devastating tumors with a very poor prognosis. Previously the authors have found that the nitrone compound OKN-007 (OKlahoma Nitrone 007; or disodium 4-[(tert-butyl-imino) methyl] benzene-1,3-disulfonate N-oxide) is effective against high-grade gliomas in various GBM rodent and human xenograft models. The purpose of the present study was to assess the levels of the lipopolysaccharide-binding protein (LBP) in rodent gliomas treated with OKN-007 as well as determine the expression of LBP in human gliomas.METHODSMicroarray analysis was done to assess altered gene expression following OKN-007 administration in an F98 glioma model. An enzyme-linked immunosorbent assay was incorporated to assess LBP levels in glioma tissues, as well as blood serum, comparing results in OKN-007–treated and untreated tumor-bearing animals. Immunohistochemistry was used to assess LBP levels in varying grades of human glioma tissue sections.RESULTSUpon further assessment of gene expression fold changes in F98 gliomas in rats that received or did not receive OKN-007, it was found that the gene for LBP was significantly downregulated by OKN-007. Further investigation was done to see whether levels of LBP were affected by OKN-007 treatment in F98 gliomas. It was found that LBP could be detected not only in glioma tissue but also in blood serum of F98 glioma-bearing rats and that OKN-007 decreased the levels of LBP. It was also found that LBP levels are highly expressed in human high-grade glioma tissues.CONCLUSIONSLBP could potentially be used as a serum diagnostic marker of treatment response in high-grade gliomas.

Perampanel Add-on to Standard Radiochemotherapy in vivo Promotes Neuroprotection in a Rodent F98 Glioma Model

An abnormal glutamate signaling of glioblastoma may contribute to both tumor progression and the generation of glioma-associated epileptic seizures. We hypothesized that the AMPA receptor antagonist perampanel (PER) could attenuate tumor growth and epileptic events. F98 glioma cells, grown orthotopically in Fischer rats, were employed as a model of glioma to investigate the therapeutic efficiency of PER (15 mg/kg) as adjuvant to standard radiochemotherapy (RCT). The epileptiform phenotype was investigated by video-EEG analysis and field potential recordings. Effects on glioma progression were estimated by tumor size quantification, survival analysis and immunohistological staining. Our data revealed that orthotopically-growing F98 glioma promote an epileptiform phenotype in rats. RCT reduced the tumor size and prolonged the survival of the animals. The adjuvant administration of PER had no effect on tumor progression. The tumor-associated epileptic events were abolished by PER application or RCT respectively, to initial baseline levels. Remarkably, PER preserved the glutamatergic network activity on healthy peritumoral tissue in RCT-treated animals. F98 tumors are not only a robust model to investigate glioma progression, but also a viable model to simulate a glioma-associated epileptiform phenotype. Furthermore, our data indicate that PER acts as a potent anticonvulsant and may protect the tumor-surrounding tissue as adjuvant to RCT, but failed to attenuate tumor growth or promote animal survival.

Study of the intracellular nanoparticle-based radiosensitization mechanisms in F98 glioma cells treated with charged particle therapy through synchrotron-based infrared microspectroscopy

This work provides new insights into the molecular changes in response to nanoparticle-based radiotherapy treatments using ion beams through synchrotron-based infrared microspectroscopy.

TB-03 THE SURVIVAL PROLONGATION EFFECT OF NOVEL BORON COMPOUND FOR BNCT USING RAT BRAIN TUMOR MODEL

INTRODUCTION Boron neutron capture therapy (BNCT) is form of tumor-cell selective particle irradiation. Although novel boron compounds have been developed, BPA (boronophenylalanine) and BSH (borocaptate sodium) are used in the clinical practice. The development of effective boron compounds is a major theme. We used Dodecaborate-containing BPA (AAL) which is combined the characteristics of both BPA and BSH. We have been conducting research on how the new compound for BNCT will affect rat brain tumor model. MATERIALS AND METHODS We evaluated the boron concentration of F98 glioma cells for BPA and AAL, and the biodistribution of these following BPA administrated intravenously (i.v.) or AAL administrated by convection-enhanced delivery (CED) in F98 glioma bearing rats. In BNCT study, the therapeutic effect was evaluated in terms of the survival time for all rats divided into six groups. RESULTS The uptake of boron showed almost the same value at all exposure times in high concentration. In biodistribution study, the AAL(CED) 6h after the termination group attained the highest boron concentrations of the tumor (59.9 ± 18.2 μg/g). In the BNCT study, the median survival time in the AAL(CED) group (31(29–35) days) was shorter than that in the BPA(i.v.) group(34(33–36) days). And the combination group of AAL(CED) and BPA(i.v.) gave the most significant prolongation of survival(38(36–40) days). DISCUSSION AAL(CED) and BPA(i.v.) combined group had a significant survival prolongation compared with the single-agent group. It is thought that AAL irradiated by thermal neutron had a cell-killing effect on cells in which BPA was not taken up. The combination uses of AAL (CED) provides additional BNCT effects. The mechanism by which AAL is incorporated has not been clarified, and further experiments including the influence on normal cells are in progress. CONCLUSION Dodecaborate-containing BPA (AAL) is a novel boron compound for BNCT that can be expected to prolong the survival time in combination with BPA.