Metabolic Impact of Anti-Angiogenic Agents on U87 Glioma Cells

Abstract

BackgroundGlioma cells not only secrete high levels of vascular endothelial growth factor (VEGF) but also express VEGF receptors (VEGFR), supporting the existence of an autocrine loop. The direct impact on glioma cells metabolism of drugs targeting the VEGF pathway, such as Bevacizumab (Bev) or VEGFR Tyrosine Kinase Inhibitor (TKI), is poorly known.Material and MethodsU87 cells were treated with Bev or SU1498, a selective VEGFR2 TKI. VEGFR expression was checked with FACS flow cytometry and Quantitative Real-Time PCR. VEGF secretion into the medium was assessed with an ELISA kit. Metabolomic studies on cells were performed using High Resolution Magic Angle Spinning Spectroscopy (HR-MAS).ResultsU87 cells secreted VEGF and expressed low level of VEGFR2, but no detectable VEGFR1. Exposure to SU1498, but not Bev, significantly impacted cell proliferation and apoptosis. Metabolomic studies with HR MAS showed that Bev had no significant effect on cell metabolism, while SU1498 induced a marked increase in lipids and a decrease in glycerophosphocholine. Accordingly, accumulation of lipid droplets was seen in the cytoplasm of SU1498-treated U87 cells.ConclusionAlthough both drugs target the VEGF pathway, only SU1498 showed a clear impact on cell proliferation, cell morphology and metabolism. Bevacizumab is thus less likely to modify glioma cells phenotype due to a direct therapeutic pressure on the VEGF autocrine loop. In patients treated with VEGFR TKI, monitoring lipids with magnetic resonance spectroscopic (MRS) might be a valuable marker to assess drug cytotoxicity.

Anti-VEGFR2 Driven Nuclear Translocation of VEGFR2 and Acquired Malignant Hallmarks are Mutation Dependent in Glioblastoma

“…In contrast, blockade of VEGF activity by Bevacizumab failed to recapitulate the impact of SU1498, suggesting that VEGFR2 -mediated neovascularization is independent of VEGF in U87 cells [27]. Similarly SU1498 treatment promoted apoptosis in U87 cells in culture [28]. VEGFR2 inhibition using monoclonal antibody (DC101) either alone or in combination with VEGFR1 monoclonal antibody/photodynamic therapy significantly reduced the tumor volume through increased tumor cell apoptosis and prolonged the survival time of U87 implanted animals [29].…”

Applications of high‐resolution magic angle spinning MRS in biomedical studies I—cell line and animal models

“…While numerous HRMAS‐based studies have investigated well established chemotherapeutics, such as cisplatin, methotrexate (MTX), doxorubicin, tamoxifen, tyrosine kinase inhibitors, and bevacizumab—mostly focused on providing a more detailed understanding of the drugs' mechanisms of action and intracellular processes triggered by these drugs, such as apoptosis—others have explored the possibilities of new agents …”

Perfluorocarbon-Loaded Lipid Nanocapsules to Assess the Dependence of U87-Human Glioblastoma Tumor pO2 on In Vitro Expansion Conditions

“…In the peculiar case of the widely used U87-MG glioma cell line for chemo-therapeutic assessments, cellular therapeutics, and MR methodological purposes [24–26], the impact of the initial culture conditions is often not recognized as a changeable parameter, even though we recently showed that the expansion of this cell line under moderate hypoxia (3% O 2 ) or under normoxia (21% O 2 ) led to significant modifications in tumor growth [13]. This observation is repeated in the present study.…”