Flavonoids from the Amazon plant Brosimum acutifolium induce C6 glioma cell line apoptosis by disrupting mitochondrial membrane potential and reducing AKT phosphorylation.

ABSTRACT

Glioblastoma, which is highly invasive and has a poor patient prognosis, is the most common type of brain tumor. Flavonoids have known antiproliferative and antineoplastic effects, such as apoptosis induction and tumor growth inhibition. We investigated the effects of treatment with three flavonoids (BAS-1, BAS-4, and BAS-6) isolated from the Amazon plant Brosimum acutifolium on the proliferation and migration of the C6 glioma cell line. Cytotoxicity was evaluated by MTT assay, and morphological changes were evaluated by phase-contrast microscopy and by transmission electron microscopy. Apoptosis was determined using Annexin V-FITC-propidium iodide (PI) staining. A hemolysis assay was used to evaluate plasma membrane injury. Antiproliferative effects were assessed by wound migration and colony formation assays. Mitochondrial transmembrane potential (ΔΨm) was determined using JC-1 dye and flow cytometry. To identify the flavonoid targets, western blotting was performed. BAS-1 and BAS-4 reduced C6 cell proliferation in a dose-dependent manner. BAS-6 showed no effect. Due to its high toxicity toward primary glial cells and its high hemolytic index, BAS-1 was not used in the remaining experiments. BAS-4 treatment did not induce cytotoxicity in primary glial cells; however, in glioma cells, it suppressed migration and invasion and led to apoptosis through mitochondrial damage, ΔΨm loss, cell cycle arrest, and reduced AKT phosphorylation, which is a component of the main cell survival pathway. We conclude that BAS-4 showed potential activity against glioma by inducing apoptosis mediated by ΔΨm loss and AKT pathway disruption, and future studies should further evaluate BAS-4 as a promising antineoplastic agent against glioblastoma.