Abstract
BackgroundCyclovirobuxine D (CVBD), a steroidal alkaloid, has multiple pharmacological activities, including anti-cancer activity. However, the anti-cancer effect of CVBD on glioblastoma (GBM) has seldom been investigated. This study explores the activity of CVBD in inducing apoptosis of GBM cells, and examines the related mechanism in depth.MethodsGBM cell lines (T98G, U251) and normal human astrocytes (HA) were treated with CVBD. Cell viability was examined by CCK-8 assay, and cell proliferation was evaluated by cell colony formation counts. Apoptosis and mitochondrial superoxide were measured by flow cytometry. All protein expression levels were determined by Western blotting. JC-1 and CM-H2DCFDA probes were used to evaluate the mitochondrial membrane potential (MMP) change and intracellular ROS generation, respectively. The cell ultrastructure was observed by transmission electron microscope (TEM). Colocalization of cofilin and mitochondria were determined by immunofluorescence assay.ResultsCVBD showed a greater anti-proliferation effect on the GBM cell lines, T98G and U251, than normal human astrocytes in dose- and time-dependent manners. CVBD induced apoptosis and mitochondrial damage in GBM cells. We found that CVBD led to mitochondrial translocation of cofilin. Knockdown of cofilin attenuated CVBD-induced apoptosis and mitochondrial damage. Additionally, the generation of ROS and mitochondrial superoxide was also induced by CVBD in a dose-dependent manner. N-acetyl-L-cysteine (NAC) and mitoquinone (MitoQ) pre-treatment reverted CVBD-induced apoptosis and mitochondrial damage. MitoQ pretreatment was able to block the mitochondrial translocation of cofilin caused by CVBD.ConclusionsOur data revealed that CVBD induced apoptosis and mitochondrial damage in GBM cells. The underlying mechanism is related to mitochondrial translocation of cofilin caused by mitochondrial oxidant stress.
Highlights
Glioma, which is the most common central nervous system cancer, accounts for about 40% to 50% of all intracranial tumors [1]
To study the effect of Cyclovirobuxine D (CVBD) on the growth of human GBM cells and normal human astrocytes (HA), the cell viabilities were determined by CCK-8 assay
We found that the cell viabilities were decreased in a dose-dependent manner in T98G and U251 cells treated with CVBD
Summary
Glioma, which is the most common central nervous system cancer, accounts for about 40% to 50% of all intracranial tumors [1]. Glioblastoma (GBM), classified as grade IV by the World Health Organization (WHO), is the most fatal and malignant type of glioma [2]. The standard therapy for GBM is surgical resection combined with local radiotherapy, and adjuvant chemotherapy with the alkylating agent temozolomide (TMZ) [5]. Patients treated with TMZ have a significantly higher survival than those treated with radiotherapy alone, the overall prognosis is still poor, and the resistance of GBM cells to TMZ is often to blame [6, 7]. There is an urgent need to find a novel and effective anti-GBM agent. The anti-cancer effect of CVBD on glioblastoma (GBM) has seldom been investigated. This study explores the activity of CVBD in inducing apoptosis of GBM cells, and examines the related mechanism in depth
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