Bevacizumab is superior to Temozolomide in causing mitochondrial dysfunction in human brain tumors

Metabolic management of microenvironment acidity in glioblastoma

Glioblastoma (GBM), similar to most cancers, is dependent on fermentation metabolism for the synthesis of biomass and energy (ATP) regardless of the cellular or genetic heterogeneity seen within the tumor. The transition from respiration to fermentation arises from the documented defects in the number, the structure, and the function of mitochondria and mitochondrial-associated membranes in GBM tissue. Glucose and glutamine are the major fermentable fuels that drive GBM growth. The major waste products of GBM cell fermentation (lactic acid, glutamic acid, and succinic acid) will acidify the microenvironment and are largely responsible for drug resistance, enhanced invasion, immunosuppression, and metastasis. Besides surgical debulking, therapies used for GBM management (radiation, chemotherapy, and steroids) enhance microenvironment acidification and, although often providing a time-limited disease control, will thus favor tumor recurrence and complications. The simultaneous restriction of glucose and glutamine, while elevating non-fermentable, anti-inflammatory ketone bodies, can help restore the pH balance of the microenvironment while, at the same time, providing a non-toxic therapeutic strategy for killing most of the neoplastic cells.

FOXO3a protects glioma cells against temozolomide-induced DNA double strand breaks via promotion of BNIP3-mediated mitophagy

FOXO3a (forkhead box transcription factor 3a) is involved in regulating multiple biological processes in cancer cells. BNIP3 (Bcl-2/adenovirus E1B 19-kDa-interacting protein 3) is a receptor accounting for priming damaged mitochondria for autophagic removal. In this study we investigated the role of FOXO3a in regulating the sensitivity of glioma cells to temozolomide (TMZ) and its relationship with BNIP3-mediated mitophagy. We showed that TMZ dosage-dependently inhibited the viability of human U87, U251, T98G, LN18 and rat C6 glioma cells with IC50 values of 135.75, 128.26, 142.65, 155.73 and 111.60 μM, respectively. In U87 and U251 cells, TMZ (200 μM) induced DNA double strand breaks (DSBs) and nuclear translocation of apoptosis inducing factor (AIF), which was accompanied by BNIP3-mediated mitophagy and FOXO3a accumulation in nucleus. TMZ treatment induced intracellular ROS accumulation in U87 and U251 cells via enhancing mitochondrial superoxide, which not only contributed to DNA DSBs and exacerbated mitochondrial dysfunction, but also upregulated FOXO3a expression. Knockdown of FOXO3a aggravated TMZ-induced DNA DSBs and mitochondrial damage, as well as glioma cell death. TMZ treatment not only upregulated BNIP3 and activated autophagy, but also triggered mitophagy by prompting BNIP3 translocation to mitochondria and reinforcing BNIP3 interaction with LC3BII. Inhibition of mitophagy by knocking down BNIP3 with SiRNA or blocking autophagy with 3MA or bafilomycin A1 exacerbated mitochondrial superoxide and intracellular ROS accumulation. Moreover, FOXO3a knockdown inhibited TMZ-induced BNIP3 upregulation and autophagy activation. In addition, we showed that treatment with TMZ (100 mg·kg-1·d-1, ip) for 12 days in C6 cell xenograft mice markedly inhibited tumor growth accompanied by inducing FOXO3a upregulation, oxidative stress and BNIP3-mediated mitophagy in tumor tissues. These results demonstrate that FOXO3a attenuates temozolomide-induced DNA double strand breaks in human glioma cells via promoting BNIP3-mediated mitophagy.

Ketogenic Metabolic Therapy, Without Chemo or Radiation, for the Long-Term Management of IDH1-Mutant Glioblastoma: An 80-Month Follow-Up Case Report

Background: Successful treatment of glioblastoma (GBM) remains futile despite decades of intense research. GBM is similar to most other malignant cancers in requiring glucose and glutamine for growth, regardless of histological or genetic heterogeneity. Ketogenic metabolic therapy (KMT) is a non-toxic nutritional intervention for cancer management. We report the case of a 32-year-old man who presented in 2014 with seizures and a right frontal lobe tumor on MRI. The tumor cells were immunoreactive with antibodies to the IDH1 (R132H) mutation, P53 (patchy), MIB-1 index (4–6%), and absent ATRX protein expression. DNA analysis showed no evidence of methylation of the MGMT gene promoter. The presence of prominent microvascular proliferation and areas of necrosis were consistent with an IDH-mutant glioblastoma (WHO Grade 4).

Methods: The patient refused standard of care (SOC) and steroid medication after initial diagnosis, but was knowledgeable and self-motivated enough to consume a low-carbohydrate ketogenic diet consisting mostly of saturated fats, minimal vegetables, and a variety of meats. The patient used the glucose ketone index calculator to maintain his Glucose Ketone Index (GKI) near 2.0 without body weight loss.

Results: The tumor continued to grow slowly without expected vasogenic edema until 2017, when the patient opted for surgical debulking. The enhancing area, centered in the inferior frontal gyrus, was surgically excised. The pathology specimen confirmed IDH1-mutant GBM. Following surgery, the patient continued with a self-administered ketogenic diet to maintain low GKI values, indicative of therapeutic ketosis. At the time of this report (May 2021), the patient remains alive with a good quality of life, except for occasional seizures. MRI continues to show slow interval progression of the tumor.

Conclusion: This is the first report of confirmed IDH1-mutant GBM treated with KMT and surgical debulking without chemo- or radiotherapy. The long-term survival of this patient, now at 80 months, could be due in part to a therapeutic metabolic synergy between KMT and the IDH1 mutation that simultaneously target the glycolysis and glutaminolysis pathways that are essential for GBM growth. Further studies are needed to determine if this non-toxic therapeutic strategy could be effective in providing long-term management for other GBM patients with or without IDH mutations.

Hypoxia-Mediated ROS Amplification Triggers Mitochondria-Mediated Apoptotic Cell Death via PD-L1/ROS-Responsive, Dual-Targeted, Drug-Laden Thioketal Nanoparticles

Amalgamation of the reactive oxygen species (ROS)-responsive stimulus with nanoparticles has gained considerable interest owing to their high tumor specificity. Hypoxia plays a pivotal role in the acceleration of intracellular ROS production. Herein, we report the construction of a cancer cell (PD-L1)- and ROS-responsive, dual-targeted, temozolomide (TMZ)-laden nanosystem which offers a better anticancer effect in a hypoxic tumor microenvironment. A dual-targeted system boosted permeation in the cancer cells. Hypoxic conditions elevating the high ROS level accelerated the in situ release of TMZ from anti-PD-L1-TKNPs. Hyperaccumulated ROS engendered from TMZ caused oxidative damage leading to mitochondria-mediated apoptosis. TMZ fabricated in the multifunctional nanosystem (anti-PD-L1-TMZ-TKNPs) provided excellent tumor accumulation and retarded tumor growth under in vivo conditions. The elevated apoptosis effect with the activation of an apoptotic marker, DNA double-strand breakage marker, and downregulation of the angiogenesis marker in the tumor tissue following treatment with anti-PD-L1-TMZ-TKNPs exerts robust anticancer effect. Collectively, the nanoconstruct offers deep tumor permeation and high drug release and broadens the application of the ROS-responsive nanosystem for a successful anticancer effect.

Platinum-based chemotherapy and bevacizumab instigate the destruction of human ovarian cancers via different signaling pathways

The standard chemotherapy regimens of ovarian cancer are platinum-based chemotherapy (carboplatin and paclitaxel) and bevacizumab (BEV). However, the effects of BEV alone or combined with carboplatin and paclitaxel on mitochondrial dynamics, mitochondrial function, mitophagy, apoptosis, inflammation and vascular endothelial growth factor (VEGF) in human ovarian cancer mitochondria and cells have not yet been investigated. Therefore, we aimed to test the hypothesis that 1) platinum-based chemotherapy and BEV equally damage isolated mitochondria from human ovarian cancers, and ovarian cancer cells through inducing mitochondrial dynamics dysregulation, mitochondrial dysfunction, increased mitophagy and apoptosis, as well as altered inflammation and VEGF; and 2) combined therapies exert greater damage than monotherapy. Each isolated human ovarian cancer mitochondria (n = 16) or CaOV3 cells (n = 6) were treated with either platinum-based chemotherapy (carboplatin 10 μM and paclitaxel 5 μM), BEV (2 mg/mL) or combined platinum-based chemotherapy and BEV for 60 min or 24 h, respectively. Following the treatment, mitochondrial dynamics, mitochondrial function, mitophagy, apoptosis, cytotoxicity, inflammation and VEGF were determined. Platinum-based chemotherapy caused ovarian cancer mitochondria and cell damage through mitochondrial dysfunction, increased cell death with impairment of membrane integrity, and enhanced VEGF reduction, while BEV did not. BEV caused deterioration of ovarian cancer mitochondria and cells through mitochondrial-dependent apoptosis, but it had no effect on cell viability. Interestingly, combined platinum-based chemotherapy and BEV treatments had no addictive effects on all parameters except mitochondrial maximal respiration, when compared to monotherapy. Collectively, these findings suggest that platinum-based chemotherapy and BEV caused human ovarian cancer mitochondrial and cell damage through different mechanisms.

Bevacizumab induces oxidative cytotoxicity and apoptosis via TRPM2 channel activation in retinal pigment epithelial cells: Protective role of glutathione

PURPOSE

Bevacizumab (BEV) is a blocker of circulating VEGF A generation. However, BEV has adverse apoptotic and cytotoxic effects via upregulation of mitochondrial reactive oxygen species (ROS) and TRPM2 activation, and downregulation of cytosolic glutathione (GSH) in neuronal cells. We investigated the possible protective effects of GSH treatment on BEV-induced oxidant and apoptotic adverse actions in the TRPM2 expressing adult retinal pigment epithelial-19 (ARPE-19) and SH-SY5Y neuronal cells.

MATERIAL AND METHODS

The ARPE-19 and SH-SY5Y cells were divided into five main groups: Control, GSH (10 mM for 2 h), BEV (0.25 mg/ml for 24 h), BEV+GSH, and BEV+TRPM2 channel blockers (ACA or 2-APB). In the SH-SY5Y cells, the Ca²⁺ analyses (Fluo-3) were performed only, although Fluo-3 and the remaining analyses were performed in the ARPE-19 cells.

RESULTS

The levels of apoptosis, cell death, mitochondrial ROS, lipid peroxidation, caspase-3, caspase-9, ADP-ribose-induced TRPM2 current density, cytosolic-free Zn²⁺, and Ca²⁺ were increased by BEV, although their levels were diminished by the treatments of GSH and TRPM2 blockers. The BEV-induced decreases of cell viability, GSH levels, and glutathione peroxidase activities were increased by the treatment of GSH. BEV-induced increase of TRPM2 expression was decreased by the treatment of GSH, although BEV-induced decrease of VEGF A expression was further decreased by the treatment of GSH.

CONCLUSION

Our data confirmed that BEV-induced mitochondrial ROS and apoptosis in the human retinal epithelial cells were modulated by GSH and TRPM2 inhibition. The treatment of GSH may be considered as a therapeutic approach to BEV-induced ARPE-19 cell injury.

Curcumin attenuates bevacizumab-induced toxicity via suppressing oxidative stress and preventing mitochondrial dysfunction in heart mitochondria

Heart failure was subsequently noted in 2-4% of patients on bevacizumab (BEV). Whereas mitochondria play an important role in myocardial tissue homeostasis, deterioration in mitochondrial function will eventually lead to cardiomyocyte cell death and consequently cardiovascular dysfunction. Therefore, the aim of our study is to search the effects of BEV on isolated rat heart mitochondria and cardiomyocytes, and survey the effect of curcumin as a mitochondrial protective and cardioprotective agent. Rat heart mitochondria and cardiomyocytes were isolated from adult rat heart ventricular. By using biochemical and flow cytometry evaluations, the parameters of mitochondrial toxicity including succinate dehydrogenase (SDH) activity, mitochondrial swelling, mitochondrial membrane potential (MMP) collapse, reactive oxygen species (ROS) formation and lipid peroxidation (LP), and cellular assays such as cytotoxicity and MMP collapse were evaluated. Results revealed that BEV (up to 50 μg/ml) induced a concentration- and time-dependent rise in mitochondrial ROS formation, MMP collapse, mitochondrial swelling, LP, and inhibition of SDH in rat heart mitochondria. Our results showed that curcumin (10-100 μM) significantly ameliorated BEV-induced mitochondrial toxicities. Also, our results in cellular assays confirmed amelioration effect of curcumin against BEV toxicity. These results indicate that the cardiotoxic effects of BEV are associated with mitochondrial dysfunction and ROS formation, which finally ends in MMP collapse and mitochondrial swelling as the "point of no return" in the cascade of events leading to apoptosis. Also, results of this study suggest that probably the combination therapy of BEV and curcumin could decrease mitochondrial effects of this drug.

Bevacizumab as a monoclonal antibody inhibits mitochondrial complex II in isolated rat heart mitochondria: ameliorative effect of ellagic acid

Drug-induced cardiotoxicity usually manifests as heart failure or left ventricular systolic dysfunction. Left ventricular dysfunction is a rarely reported side effect of bevacizumab (BEV) with an incidence of 1.2%, and this occurs irrespective of the route of administration. In this study, we focused on an analysis of BEV effects on mitochondrial complexes activities and protective effect of ellagic acid (EA) against BEV-induced mitochondria toxicity. Rat heart mitochondria were isolated using differential centrifugation form wistar rats. Using biochemical and flowcytometry assays we evaluated mitochondrial complexes activity, succinate dehydrogenases (SDH), mitochondrial swelling, reactive oxygen species (ROS) formation and mitochondrial membrane potential (MMP) in isolated mitochondria. We observed only decreased activity of complexes II after exposure with BEV (50 and 100 µg/ml). The inhibition of complex II is paralleled by the decreased MMP, mitochondrial swelling, and ROS formation. Also, we showed that EA (10-100 µM) as an antioxidant and natural agent significantly decreases mitochondrial toxicity induced by BEV. Together, for the first time, this preliminary study has demonstrated a significant decrease in activity of complexes II after exposure with BEV and proved the protective effects of EA in alleviating BEV-mediated mitochondria toxicity.

Provocative Question: Should Ketogenic Metabolic Therapy Become the Standard of Care for Glioblastoma?

No major advances have been made in improving overall survival for glioblastoma (GBM) in almost 100 years. The current standard of care (SOC) for GBM involves immediate surgical resection followed by radiotherapy with concomitant temozolomide chemotherapy. Corticosteroid (dexamethasone) is often prescribed to GBM patients to reduce tumor edema and inflammation. The SOC disrupts the glutamate-glutamine cycle thus increasing availability of glucose and glutamine in the tumor microenvironment. Glucose and glutamine are the prime fermentable fuels that underlie therapy resistance and drive GBM growth through substrate level phosphorylation in the cytoplasm and the mitochondria, respectively. Emerging evidence indicates that ketogenic metabolic therapy (KMT) can reduce glucose availability while elevating ketone bodies that are neuroprotective and non-fermentable. Information is presented from preclinical and case report studies showing how KMT could target tumor cells without causing neurochemical damage thus improving progression free and overall survival for patients with GBM.

Autophagy modulates temozolomide-induced cell death in alveolar Rhabdomyosarcoma cells

Rhabdomyosarcoma (RMS) is a muscle-derived tumor. In both pre-clinical and clinical studies Temozolomide (TMZ) has been recently tested against RMS; however, the precise mechanism of action of TMZ in RMS remains unclear. Here we demonstrate that TMZ decreases the cell viability of the RH30 RMS and C2C12 cell line, where cells display evidence of mitochondrial outer membrane permeability. Interestingly, the C2C12 mouse myoblast line was relatively more resistant to TMZ-induced apoptosis. Moreover, we observed that TMZ activated biochemical and morphological markers of autophagy in both cell lines. Autophagy inhibition in both RH30 and C2C12 cells significantly increased TMZ-induced cell death. In RH30 cells, TMZ increased Mcl-1 and Bax protein expression compared to corresponding time match controls while in C2C12 Mcl-1, Bcl-2, Bcl-XL, and Bax protein expression were not changed. Baf-A1 co-treatment with TMZ significantly decrease Mcl-1 expression compared to TMZ while increase Bax expression in C2C12 cells (Bcl2 and Bcl-XL do not significantly change in Baf-A1/TMZ co-treatment). Using a three-dimensional (3D) C2C12 and RH30 culture model we demonstrated that TMZ is significantly more toxic in RH30 cells (live/dead assay). Additionally, we have observed in our 3D culture model that TMZ induced both apoptosis (cleavage of PARP) and autophagy (LC3-puncta and localization of LC3/p62). Therefore, our data demonstrate that TMZ induces simultaneous autophagy and apoptosis in both RH30 and C2C12 cells in 2D and 3D culture model, where RH30 cells are more sensitive to TMZ-induced death. Furthermore, autophagy serves to protect RH30 cells from TMZ-induced death.