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result(s) for
"Zaher, Amira"
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Breaking the Feedback Loop of β-Cell Failure: Insight into the Pancreatic β-Cell’s ER-Mitochondria Redox Balance
2025
Pancreatic β-cells rely on a delicate balance between the endoplasmic reticulum (ER) and mitochondria to maintain sufficient insulin stores for the regulation of whole animal glucose homeostasis. The ER supports proinsulin maturation through oxidative protein folding, while mitochondria supply the energy and redox buffering that maintain ER proteostasis. In the development of Type 2 diabetes (T2D), the progressive decline of β-cell function is closely linked to disruptions in ER-mitochondrial communication. Mitochondrial dysfunction is a well-established driver of β-cell failure, whereas the downstream consequences for ER redox homeostasis have only recently emerged. This interdependence of ER-mitochondrial functions suggests that an imbalance is both a cause and consequence of metabolic dysfunction. In this review, we discuss the regulatory mechanisms of ER redox control and requirements for mitochondrial function. In addition, we describe how ER redox imbalances may trigger mitochondrial dysfunction in a vicious feed forward cycle that accelerates β-cell dysfunction and T2D onset.
Journal Article
Mitochondrial Superoxide Dismutase in Cisplatin-Induced Kidney Injury
by
Zaher, Amira
,
Allen, Bryan G.
,
Spitz, Douglas R.
in
acute kidney injury
,
adverse effects
,
antineoplastic activity
2021
Cisplatin is a chemotherapy agent commonly used to treat a wide variety of cancers. Despite the potential for both severe acute and chronic side effects, it remains a preferred therapeutic option for many malignancies due to its potent anti-tumor activity. Common cisplatin-associated side-effects include acute kidney injury (AKI) and chronic kidney disease (CKD). These renal injuries may cause delays and potentially cessation of cisplatin therapy and have long-term effects on renal function reserve. Thus, developing mechanism-based interventional strategies that minimize cisplatin-associated kidney injury without reducing efficacy would be of great benefit. In addition to its action of cross-linking DNA, cisplatin has been shown to affect mitochondrial metabolism, resulting in mitochondrially derived reactive oxygen species (ROS). Increased ROS formation in renal proximal convoluted tubule cells is associated with cisplatin-induced AKI and CKD. We review the mechanisms by which cisplatin may induce AKI and CKD and discuss the potential of mitochondrial superoxide dismutase mimetics to prevent platinum-associated nephrotoxicity.
Journal Article
Pharmacological ascorbate as a novel therapeutic strategy to enhance cancer immunotherapy
by
Petronek, Michael S.
,
Zaher, Amira
,
Hartwig, Stacey M.
in
anti-PD-1
,
Antineoplastic Agents - therapeutic use
,
antioxidant therapy
2022
Pharmacological ascorbate (i.e., intravenous infusions of vitamin C reaching ~ 20 mM in plasma) is under active investigation as an adjuvant to standard of care anti-cancer treatments due to its dual redox roles as an antioxidant in normal tissues and as a prooxidant in malignant tissues. Immune checkpoint inhibitors (ICIs) are highly promising therapies for many cancer patients but face several challenges including low response rates, primary or acquired resistance, and toxicity. Ascorbate modulates both innate and adaptive immune functions and plays a key role in maintaining the balance between pro and anti-inflammatory states. Furthermore, the success of pharmacological ascorbate as a radiosensitizer and a chemosensitizer in pre-clinical studies and early phase clinical trials suggests that it may also enhance the efficacy and expand the benefits of ICIs.
Journal Article
Antimicrobial printed linen fabric by using brewer’s yeast enzyme
by
Zaher, Amira Ragheb
,
Ibrahim, Nermin Atef
,
El-Hennawi, Heba Mohamed
in
Antibacterial activity
,
Brewer’s yeast enzyme
,
Coliforms
2024
Background
In this research, a brewer’s yeast suspension was used to biotreat raw linen fibers under a range of different circumstances utilizing an ultrasonic cleaner device. In order to optimize circumstances for the treatment process, this extensive work is focused on examining the variables that could affect the biotreatment, such as the amount of brewer’s yeast used, the duration, the temperature of the treatment, and the pH throughout the treatment. After enzymatic treatment, the printing process utilizing turmeric natural dye was used. Variable assesses were conducted to determine the steaming time, thermofixation time, pH of the printing paste, types of dyes, and types of fabrics. How these elements affected the wettability and fabric color strength is investigated. To better comprehend, scanning electron microscope (SEM) was used to study the morphology of treated and untreated linen samples. The effects of treating the fibers with yeast enzyme on their multifunctional qualities, such as color and antibacterial activity against gram-positive bacteria like
Staphylococcus
aureus
and gram-negative bacteria like
Escherichia coli
, were assessed.
Results
Results demonstrated that the enzyme extract, which predominantly contains lipase, amylase, and protease enzymes that develop the fabric printability, is responsible for the increase of color strength which increased by about 152.27% with good fastness properties compared by the untreated printed samples.
Conclusions
The overall findings showed that the treated fabrics have superior color fastness and antibacterial properties when compared to the untreated fabrics, demonstrating that the procedure of production used to create these multifunctional linen fabrics is environmentally friendly.
Journal Article
Exploratory Analysis of Image-Guided Ionizing Radiation Delivery to Induce Long-Term Iron Accumulation and Ferritin Expression in a Lung Injury Model: Preliminary Results
2024
Background: Radiation therapy (RT) is an integral and commonly used therapeutic modality for primary lung cancer. However, radiation-induced lung injury (RILI) limits the irradiation dose used in the lung and is a significant source of morbidity. Disruptions in iron metabolism have been linked to radiation injury, but the underlying mechanisms remain unclear. Purpose: To utilize a targeted radiation delivery approach to induce RILI for the development of a model system to study the role of radiation-induced iron accumulation in RILI. Methods: This study utilizes a Small Animal Radiation Research Platform (SARRP) to target the right lung with a 20 Gy dose while minimizing the dose delivered to the left lung and adjacent heart. Long-term pulmonary function was performed using RespiRate-x64image analysis. Normal-appearing lung volumes were calculated using a cone beam CT (CBCT) image thresholding approach in 3D Slicer software. Quantification of iron accumulation was performed spectrophotometrically using a ferrozine-based assay as well as histologically using Prussian blue and via Western blotting for ferritin heavy chain expression. Results: Mild fibrosis was seen histologically in the irradiated lung using hematoxylin and eosin-stained fixed tissue at 9 months, as well as using a scoring system from CBCT images, the Szapiel scoring system, and the highest fibrotic area metric. In contrast, no changes in breathing rate were observed, and median survival was not achieved up to 36 weeks following irradiation, consistent with mild lung fibrosis when only one lung was targeted. Our study provided preliminary evidence on increased iron content and ferritin heavy chain expression in the irradiated lung, thus warranting further investigation. Conclusions: A targeted lung irradiation model may be a useful approach for studying the long-term pathological effects associated with iron accumulation and RILI following ionizing radiation.
Journal Article
Superoxide Dismutase Mimetic Avasopasem Manganese Enhances Radiation Therapy Effectiveness in Soft Tissue Sarcomas and Accelerates Wound Healing
2024
Soft tissue sarcomas (STSs) are mesenchymal malignant lesions that develop in soft tissues. Despite current treatments, including radiation therapy (RT) and surgery, STSs can be associated with poor patient outcomes and metastatic recurrences. Neoadjuvant radiation therapy (nRT), while effective, is often accompanied by severe postoperative wound healing complications due to damage to the surrounding normal tissues. Thus, there is a need to develop therapeutic approaches to reduce nRT toxicities. Avasopasem manganese (AVA) is a selective superoxide dismutase mimetic that protects against IR-induced oral mucositis and lung fibrosis. We tested the efficacy of AVA in enhancing RT in STSs and in promoting wound healing. Using colony formation assays and alkaline comet assays, we report that AVA selectively enhanced the STS (liposarcoma, fibrosarcoma, leiomyosarcoma, and MPNST) cellular response to radiation compared to normal dermal fibroblasts (NDFs). AVA is believed to selectively enhance radiation therapy by targeting differential hydrogen peroxide clearance in tumor cells compared to non-malignant cells. STS cells demonstrated increased catalase protein levels and activity compared to normal fibroblasts. Additionally, NDFs showed significantly higher levels of GPx1 activity compared to STSs. The depletion of glutathione using buthionine sulfoximine (BSO) sensitized the NDF cells to AVA, suggesting that GPx1 may, in part, facilitate the selective toxicity of AVA. Finally, AVA significantly accelerated wound closure in a murine model of wound healing post RT. Our data suggest that AVA may be a promising combination strategy for nRT therapy in STSs.
Journal Article
Balanced Duality: H2O2-Based Therapy in Cancer and Its Protective Effects on Non-Malignant Tissues
by
Petronek, Michael S.
,
Zaher, Amira
,
Allen, Bryan G.
in
Antioxidants
,
Cancer therapies
,
Cell death
2024
Conventional cancer therapy strategies, although centered around killing tumor cells, often lead to severe side effects on surrounding normal tissues, thus compromising the chronic quality of life in cancer survivors. Hydrogen peroxide (H2O2) is a secondary signaling molecule that has an array of functions in both tumor and normal cells, including the promotion of cell survival pathways and immune cell modulation in the tumor microenvironment. H2O2 is a reactive oxygen species (ROS) crucial in cellular homeostasis and signaling (at concentrations maintained under nM levels), with increased steady-state levels in tumors relative to their normal tissue counterparts. Increased steady-state levels of H2O2 in tumor cells, make them vulnerable to oxidative stress and ultimately, cell death. Recently, H2O2-producing therapies—namely, pharmacological ascorbate and superoxide dismutase mimetics—have emerged as compelling complementary treatment strategies in cancer. Both pharmacological ascorbate and superoxide dismutase mimetics can generate excess H2O2 to overwhelm the impaired H2O2 removal capacity of cancer cells. This review presents an overview of H2O2 metabolism in the physiological and malignant states, in addition to discussing the anti-tumor and normal tissue-sparing mechanism(s) of, and clinical evidence for, two H2O2-based therapies, pharmacological ascorbate and superoxide dismutase mimetics.
Journal Article
Gallium Uncouples Iron Metabolism to Enhance Glioblastoma Radiosensitivity
by
Owusu, Stephenson B.
,
Petronek, Michael S.
,
Zaher, Amira
in
Biosynthesis
,
Brain Neoplasms - metabolism
,
Brain Neoplasms - pathology
2024
Gallium-based therapy has been considered a potentially effective cancer therapy for decades and has recently re-emerged as a novel therapeutic strategy for the management of glioblastoma tumors. Gallium targets the iron-dependent phenotype associated with aggressive tumors by mimicking iron in circulation and gaining intracellular access through transferrin-receptor-mediated endocytosis. Mechanistically, it is believed that gallium inhibits critical iron-dependent enzymes like ribonucleotide reductase and NADH dehydrogenase (electron transport chain complex I) by replacing iron and removing the ability to transfer electrons through the protein secondary structure. However, information regarding the effects of gallium on cellular iron metabolism is limited. As mitochondrial iron metabolism serves as a central hub of the iron metabolic network, the goal of this study was to investigate the effects of gallium on mitochondrial iron metabolism in glioblastoma cells. Here, it has been discovered that gallium nitrate can induce mitochondrial iron depletion, which is associated with the induction of DNA damage. Moreover, the generation of gallium-resistant cell lines reveals a highly unstable phenotype characterized by impaired colony formation associated with a significant decrease in mitochondrial iron content and loss of the mitochondrial iron uptake transporter, mitoferrin-1. Moreover, gallium-resistant cell lines are significantly more sensitive to radiation and have an impaired ability to repair any sublethal damage and to survive potentially lethal radiation damage when left for 24 h following radiation. These results support the hypothesis that gallium can disrupt mitochondrial iron metabolism and serve as a potential radiosensitizer.
Journal Article
Differential H2O2 Metabolism among Glioblastoma Subtypes Confers Variable Responses to Pharmacological Ascorbate Therapy Combined with Chemoradiation
2023
Glioblastoma (GBM), a highly lethal and aggressive central nervous system malignancy, presents a critical need for targeted therapeutic approaches to improve patient outcomes in conjunction with standard-of-care (SOC) treatment. Molecular subtyping based on genetic profiles and metabolic characteristics has advanced our understanding of GBM to better predict its evolution, mechanisms, and treatment regimens. Pharmacological ascorbate (P-AscH−) has emerged as a promising supplementary cancer therapy, leveraging its pro-oxidant properties to selectively kill malignant cells when combined with SOC. Given the clinical challenges posed by the heterogeneity and resistance of various GBM subtypes to conventional SOC, our study assessed the response of classical, mesenchymal, and proneural GBM to P-AscH−. P-AscH− (20 pmol/cell) combined with SOC (5 µM temozolomide and 4 Gy of radiation) enhanced clonogenic cell killing in classical and mesenchymal GBM subtypes, with limited effects in the proneural subtype. Similarly, following exposure to P-AscH− (20 pmol/cell), single-strand DNA damage significantly increased in classical and mesenchymal but not proneural GBM. Moreover, proneural GBM exhibited increased hydrogen peroxide removal rates, along with increased catalase and glutathione peroxidase activities compared to mesenchymal and classical GBM, demonstrating an altered H2O2 metabolism that potentially drives differential P-AscH− toxicity. Taken together, these data suggest that P-AscH− may hold promise as an approach to improve SOC responsiveness in mesenchymal GBMs that are known for their resistance to SOC.
Journal Article
Balanced Duality: H 2 O 2 -Based Therapy in Cancer and Its Protective Effects on Non-Malignant Tissues
by
Zaher, Amira
,
Mapuskar, Kranti A
,
Allen, Bryan G
in
Animals
,
Ascorbic Acid - metabolism
,
Ascorbic Acid - pharmacology
2024
Conventional cancer therapy strategies, although centered around killing tumor cells, often lead to severe side effects on surrounding normal tissues, thus compromising the chronic quality of life in cancer survivors. Hydrogen peroxide (H
O
) is a secondary signaling molecule that has an array of functions in both tumor and normal cells, including the promotion of cell survival pathways and immune cell modulation in the tumor microenvironment. H
O
is a reactive oxygen species (ROS) crucial in cellular homeostasis and signaling (at concentrations maintained under nM levels), with increased steady-state levels in tumors relative to their normal tissue counterparts. Increased steady-state levels of H
O
in tumor cells, make them vulnerable to oxidative stress and ultimately, cell death. Recently, H
O
-producing therapies-namely, pharmacological ascorbate and superoxide dismutase mimetics-have emerged as compelling complementary treatment strategies in cancer. Both pharmacological ascorbate and superoxide dismutase mimetics can generate excess H
O
to overwhelm the impaired H
O
removal capacity of cancer cells. This review presents an overview of H
O
metabolism in the physiological and malignant states, in addition to discussing the anti-tumor and normal tissue-sparing mechanism(s) of, and clinical evidence for, two H
O
-based therapies, pharmacological ascorbate and superoxide dismutase mimetics.
Journal Article