Temozolomide, Simvastatin and Acetylshikonin Combination Induces Mitochondrial-Dependent Apoptosis in GBM Cells, Which Is Regulated by Autophagy.

Glioblastoma multiforme (GBM) is one of the deadliest cancers. Temozolomide (TMZ) is the most common chemotherapy used for GBM patients. Recently, combination chemotherapy strategies have had more effective antitumor effects and focus on slowing down the development of chemotherapy resistance. A combination of TMZ and cholesterol-lowering medications (statins) is currently under investigation in in vivo and clinical trials. In our current investigation, we have used a triple-combination therapy of TMZ, Simvastatin (Simva), and acetylshikonin, and investigated its apoptotic mechanism in GBM cell lines (U87 and U251). We used viability, apoptosis, reactive oxygen species, mitochondrial membrane potential (MMP), caspase-3/-7, acridine orange (AO) and immunoblotting autophagy assays. Our results showed that a TMZ/Simva/ASH combination therapy induced significantly more apoptosis compared to TMZ, Simva, ASH, and TMZ/Simva treatments in GBM cells. Apoptosis via TMZ/Simva/ASH treatment induced mitochondrial damage (increase of ROS, decrease of MMP) and caspase-3/7 activation in both GBM cell lines. Compared to all single treatments and the TMZ/Simva treatment, TMZ/Simva/ASH significantly increased positive acidic vacuole organelles. We further confirmed that the increase of AVOs during the TMZ/Simva/ASH treatment was due to the partial inhibition of autophagy flux (accumulation of LC3ß-II and a decrease in p62 degradation) in GBM cells. Our investigation also showed that TMZ/Simva/ASH-induced cell death was depended on autophagy flux, as further inhibition of autophagy flux increased TMZ/Simva/ASH-induced cell death in GBM cells. Finally, our results showed that TMZ/Simva/ASH treatment potentially depends on an increase of Bax expression in GBM cells. Our current investigation might open new avenues for a more effective treatment of GBM, but further investigations are required for a better identification of the mechanisms.

Jatropha-6(17),11E-diene class derivatives induce apoptosis effects in OVCAR-3 and Caov-4 ovarian cancer cell lines via a mitochondrial pathway.

We investigated the molecular mechanism of apoptosis induced by novel jatropha-6(17),11E-diene class derivatives, compounds A, B, and C that were extracted from Euphorbia osyridea Boiss, in the ovarian cancer cell lines Caov-4 and OVCAR-3. The OVCAR-3 and Caov-4 cell lines were treated with different concentrations of these compounds. Cytotoxicity was evaluated using MTT, clonogenic survival assay, and flow cytometry assays. The production of reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), and the activity of caspase 3 and 9 were evaluated. Compounds A, B, and C reduced cell viability in a dose-dependent manner (P < 0.05). The IC50 values were calculated as 46.27 ± 3.86, and 38.81 ± 3.30 µmol/L for compound A, 36.48 ± 3.18 and 42.59 ± 4.50 µmol/L for compound B, and 85.86 ± 6.75 and 75.65 ± 2.56 µmol/L for compound C against the Caov-4 and OVCAR-3 cell lines, respectively. Apoptosis evaluation showed that jatrophane derivatives increase both early and late apoptosis (P < 0.01). These compounds also increased ROS generation, ΔΨm, and the activity of caspase 3 and 9 in the treated cells. These results showed that compounds A and B have significant inhibitory effects on OVCAR-3 and Caov-4 proliferation and induction of apoptosis.

Activation of A2b adenosine receptor regulates ovarian cancer cell growth: involvement of Bax/Bcl-2 and caspase-3.

A2b adenosine receptor (A2bAR) acts as a potent regulator of cell growth in various cell lines. The present study was designed to understand the controlling mechanism of A2bAR agonist (NECA)-induced apoptosis in ovarian cancer cells. Real-time PCR and western blotting assays were used to evaluate the gene and protein expression profiles of A2bAR, respectively. MTT assay was used to study the cell proliferation effect of A2bAR agonist (NECA). Detection of apoptosis was conducted using annexin V-FITC/PI staining, caspase-3 activation assay, and the expression of Bax and Bcl-2 proteins analysis. The mitochondrial membrane potential (ΔΨM) was analyzed by employing JC-1 prob. The mRNA and protein expression levels of A2bAR in ovarian cancer cells were detected. NECA significantly reduced cell viability in a dose-dependent manner in OVCAR-3 and Caov-4 cell lines. The growth inhibition effect of NECA was related to the induction of cell apoptosis, which was manifested by annexin V-FITC staining, activation of caspase-3, and loss of mitochondrial membrane potentials (ΔΨm). In addition, downregulation of the regulatory protein Bcl-2 and upregulation of Bax protein by NECA were also observed. These findings demonstrated that NECA induces apoptosis via the mitochondrial signaling pathway. Thus, A2bAR agonists may be a potential agent for induction of apoptosis in ovarian cancer cells.

Britannin, a sesquiterpene lactone, inhibits proliferation and induces apoptosis through the mitochondrial signaling pathway in human breast cancer cells.

Induction of apoptosis in cancer cells can be a promising treatment method in cancer therapy. Naturally derived products had drawn growing attention as agent in cancer therapy. The main target of anticancer drugs may be distinct, but eventually, they lead to identical cell death pathway, which is apoptosis. Here, we indicated that britannin, a sesquiterpene lactone isolated from Asteraceae family, has antiproliferative activity on the MCF-7 and MDA-MB-468 human breast cancer cells. Annexin V/propidium iodide (PI) staining, Hoechst 33258 staining, and caspase-3/9 activity assay confirmed that britannin is able to induce apoptosis in MCF-7 and MDA-MB-468 cells. The Western blot analysis showed that the expression of Bcl-2 was noticeably decreased in response to britannin treatment, while the expression of Bax protein was increased, which were positively correlated with elevated expression of p53. Moreover, britannin also increased reactive oxygen species (ROS) generation which in turn triggered the loss of mitochondrial transmembrane potential (ΔΨm) and the subsequent release of cytochrome c from mitochondria into cytosol. Taken together, these results suggest that britannin inhibits growth of MCF-7 and MDA-MB-468 breast cancer cells through the activation of the mitochondrial apoptotic pathway and may potentially serve as an agent for breast cancer therapy.

Mitochondrial and caspase pathways are involved in the induction of apoptosis by IB-MECA in ovarian cancer cell lines.

A3 adenosine receptor agonist (IB-MECA) has been shown to play important roles in cell proliferation and apoptosis in a variety of cancer cell lines. The present study was designed to understand the mechanism underlying IB-MECA-induced apoptosis in human ovarian cancer cell lines. The messenger RNA (mRNA) and protein expression levels of A3 adenosine receptor were detected in OVCAR-3 and Caov-4 ovarian cancer cells. IB-MECA was capable of decreasing intracellular cyclic adenosine monophosphate (cAMP) that was the reason for the presence of functional A3 adenosine receptor on the cell lines. IB-MECA significantly reduced cell viability in a dose-dependent manner. Cytotoxicity of IB-MECA was suppressed by MRS1220, an A3 adenosine receptor antagonist. The growth inhibition effect of IB-MECA was related to the induction of cell apoptosis, which was manifested by annexin V-FITC staining, activation of caspase-3 and caspase-9, and loss of mitochondrial membrane potentials (ΔΨm). In addition, downregulation of the regulatory protein Bcl-2 and upregulation of Bax protein by IB-MECA were also observed. These findings demonstrated that IB-MECA induces apoptosis via the mitochondrial signaling pathway. These suggest that A3 adenosine receptor agonists may be a potential agent for induction of apoptosis in human ovarian cancer cells.