Free Radical-induced Apoptosis Research Articles

Selenomethionine and Methioninase: Selenium Free Radical Anticancer Activity.

Colloidal selenium, was first used to treat cancer as early as 1911 in both humans and mice. Selenium was identified as the toxic component in forage plants of sheep, cattle, and horses in the 1930s. The animal toxicity of selenium compounds was determined to be from the metabolism by animals of the elevated concentrations of Se-methylselenocysteine and selenomethionine in plants. The metabolism of both Se-methylselenocysteine and selenomethionine by animals gives rise to the metabolite, methylselenide (CH3Se-), which if in sufficient concentration oxidizes thiols and generates superoxide and other reactive oxygen species. Cancer cells that may overly express methionine gamma-lyase, or beta-lyase (methioninase), by induced viral genomic expression, are susceptible to free radical-induced apoptosis from selenomethionine or Se-methylselenocysteine supplementation.

Synthesis of protocatechuic acid grafted chitosan copolymer: Structure characterization and in vitro neuroprotective potential

Excessive free radicals can cause oxidative damage to human tissues, which results in a variety of diseases. Therefore, the development of antioxidant materials is one of the great projects in biomedical field. In this work, antioxidant protocatechuic acid (PCA) monomers were grafted onto chitosan (CS) backbones to develop a PCA grafted chitosan (PCA-g-CS) antioxidant copolymer via the method of free radical-induced grafting reaction. The formation of covalent bonds between PCA and CS were confirmed by FTIR, 1H NMR, XRD and UV–vis. The antioxidant activity of PCA-g-CS was analyzed by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assays. In addition, the cytotoxicity of PCA-g-CS on neuron-like rat phaeochromocytoma (PC12) cells was evaluated by using MTT assay. The neuroprotective effects against hydrogen peroxide (H2O2) and l-glutamic acid (GLU) induced apoptosis in PC12 cells were also investigated. Our results demonstrated that the PCA-g-CS antioxidant copolymer had the ability to scavenge DPPH and hydroxyl radical in vitro. Furthermore, the PCA-g-CS was biocompatible and had neuroprotective effects against free radical-induced apoptosis in PC12 cells. This PCA-g-CS copolymer is firstly synthesized for neuroprotection and the results suggest the PCA-g-CS may be a potential antioxidant material in the treatment of oxidative damage related diseases.

Anti-apoptotic role of spermine against lead and/or gamma irradiation-induced hepatotoxicity in male rats.

Exposure to either lead (Pb) or γ-irradiation (IR) results in oxidative stress in biological systems. Herein, we explored the potential anti-apoptotic effect of spermine (Spm) against lead and/or γ-irradiation-induced hepatotoxicity in male albino rats. Rats were divided into eight experimental groups of ten rats each: groups including negative control, whole body γ-irradiated (6Gray (Gy)), lead acetate (PbAct) trihydrate orally administered (75mg/kg bw≡40mg/kg bw Pb for 14 consecutive days), and Spm intraperitoneally dosed (10mg/kg bw for 14 consecutive days) rats and groups subjected to combinations of Pb+IR, Spm+IR, Spm+Pb, and Spm+Pb followed by IR on day 14 (Spm+Pb+IR). A significant decrease in arginase activity as well as mRNA and protein levels of Bcl-2 and p21 was observed in rats intoxicated with Pb and/or γ-irradiation compared to controls, whereas Bax mRNA and protein levels were significantly increased. Also, an increased level of nitric oxide (NO) with a reduced arginase activity was observed in liver tissues of intoxicated rats. Spm co-treatment with lead and/or γ-irradiation attenuated the increase in Bax mRNA and protein expression, while it restored those of Bcl-2 and p21 together with NO levels and arginase activity to control values. Altogether, we suggest that Spm may be useful in combating free radical-induced apoptosis in Pb-intoxicated and/or γ-irradiated rats.

MCF-7 유방암 세포에서 영릉향 추출물에 의한 Apoptosis 유도에 관한 연구

The extract from Lysimachia foenum-graecum (LFE) has been known to possess various instructive characters including anti-oxidant, anti-obesity, fungicidal activities. However, the accurate mechanism of those effects of LFE is not well known. In that respect, we evaluated the apoptotic effect and anti-cancer efficacy of extracts of LFE in MCF-7 breast cancer cells. In this study, we hypothesized that LFE may exert cancer cell apoptosis through regulating p53 and mitochondria-mediated apoptotic proteins. And this substance can generate ROS to cause free radical-induced apoptosis. Accordingly, the generation of ROS by LFE triggers the activation of p53 which are accompanied by pro-apoptotic protein activation and suppression of pro-survival proteins. We determined with MTT assay, flow cytometry for detection of intracellular ROS and Annexin V-PI staining, Western blotting. Consequently, our researches demonstrated that the treatment of LFE to breast cancer cells resulted in an activation of p53, Puma, Bax, cleaved-PARP and an inhibition of Bcl-2 expressions.

QS93. Modulation of Heat Shock Protein Expression in Human Gastric Epithelium: Effect of Oxygen Free Radical Induced Apoptosis

QS93. Modulation of Heat Shock Protein Expression in Human Gastric Epithelium: Effect of Oxygen Free Radical Induced Apoptosis

Versican protects cells from oxidative stress-induced apoptosis

Oxidant injury plays a critical role in the degenerative changes that are characterized by a decline in parenchymal cell numbers and viability, and occur with aging and in the etiology of many diseases. The extracellular proteoglycan versican is widely distributed in the extracellular matrix surrounding the cells. This study examines whether versican plays a role in protecting cells from free radical-induced apoptosis. Stable expression of versican or its C-terminal domain significantly decreased H(2)O(2)-induced cellular apoptosis. Cells in adherent monolayer were more resistant to H(2)O(2)-induced apoptosis than cells cultured in suspension. While vigorous trypsinization caused integrin cleavage and rendered the cells more susceptible to H(2)O(2)-induced damages, expression of versican or its C-terminal domain enhanced cell attachment and expression of beta1 integrin and fibronectin. Enhanced cell-matrix interaction by addition of manganese (MnCl(2)) to cultures also significantly diminished H(2)O(2)-induced apoptosis. The results suggest that versican plays an important role in reducing oxidant injury through an enhancement of cell-matrix interaction.

Inhibition of Mitochondrial Respiration: A NOVEL STRATEGY TO ENHANCE DRUG-INDUCED APOPTOSIS IN HUMAN LEUKEMIA CELLS BY A REACTIVE OXYGEN SPECIES-MEDIATED MECHANISM

Cancer cells are under intrinsic increased oxidative stress and vulnerable to free radical-induced apoptosis. Here, we report a strategy to hinder mitochondrial electron transport and increase superoxide O2. radical generation in human leukemia cells as a novel mechanism to enhance apoptosis induced by anticancer agents. This strategy was first tested in a proof-of-principle study using rotenone, a specific inhibitor of mitochondrial electron transport complex I. Partial inhibition of mitochondrial respiration enhances electron leakage from the transport chain, leading to an increase in O2. generation and sensitization of the leukemia cells to anticancer agents whose action involve free radical generation. Using leukemia cells with genetic alterations in mitochondrial DNA and biochemical approaches, we further demonstrated that As2O3, a clinically active anti-leukemia agent, inhibits mitochondrial respiratory function, increases free radical generation, and enhances the activity of another O2.-generating agent against cultured leukemia cells and primary leukemia cells isolated from patients. Our study shows that interfering mitochondrial respiration is a novel mechanism by which As2O3 increases generation of free radicals. This novel mechanism of action provides a biochemical basis for developing new drug combination strategies using As2O3 to enhance the activity of anticancer agents by promoting generation of free radicals.

β1-Integrin-mediated Glioma Cell Adhesion and Free Radical-induced Apoptosis Are Regulated by Binding to a C-terminal Domain of PG-M/Versican

Integrins are cell-surface glycoproteins that mediate cell activities, including tissue morphogenesis, development, immune response, and cancer, through interaction with extracellular proteins. Here we report a novel means by which integrin signaling and functions are regulated. In pull-down assays and immunoprecipitation, beta(1)-integrin bound to the C-terminal domain of PG-M/versican, an extracellular chondroitin sulfate proteoglycan. This was confirmed by cell-surface binding assays. Binding was calcium- and manganese-dependent. Upon native gel electrophoresis, beta(1)-integrin comigrated with the C-terminal domain of PG-M/versican. The interaction of beta(1)-integrin with the C-terminal domain of PG-M/versican activated focal adhesion kinase, enhanced integrin expression, and promoted cell adhesion. As a result, cells expressing the C-terminal domain of PG-M/versican were resistant to free radical-induced apoptosis. As the PG-M/versican peptide used in this study does not contain the RGD consensus-binding motif for integrins, the mechanism of the observed binding represents an entirely new function.

Correlation of metallothionein expression with apoptosis in nasopharyngeal carcinoma.

The expression of metallothionein (MT), an intracellular ubiquitous low molecular weight protein thiol with antioxidant properties, was studied in nasopharyngeal cancer (NPC) and correlated with the apoptotic index. Immunohistochemical staining of randomly selected, formalin-fixed and paraffin-embedded normal and malignant nasopharyngeal tissues were analysed for the expression of MT using the commercially available E9 antibody directed against MT I and MT II isoforms. The corresponding apoptosis labelling indices were evaluated by the TUNEL method. Localization of MT at the ultrastructural level was studied by immunogold labelling. All the tumour sections (17 specimens) showed MT-immunopositivity. A direct correlation between the percentage of MT-positive cells and the staining intensity was noted (P< 0.001; Pearson's r = 0.95). There was absence of cytoplasmic staining and only nuclear staining (with localization in the nucleoplasm) was demonstrated in the tumour cells. In normal epithelium of the nasopharynx, the basal layer was stained. An inverse relationship was observed between the level of MT expression and the apoptotic index in the NPC tissues (P = 0.0059; Pearson's r = –0.6380). The results suggest that overexpression of MT in NPC may protect the tumour cells from entering into the apoptotic process and thereby contribute to tumour expansion. Preferential localization of MT in the nuclei of NPC cells may possibly enhance radioresistance since radiotherapy is known to eradicate tumour cells by free radical-induced apoptosis. © 2000 Cancer Research Campaign

Effects of Morphine on Free Radical-induced Apoptosis of Human Neuroblastoma SH-SY5Y Cells

Effects of Morphine on Free Radical-induced Apoptosis of Human Neuroblastoma SH-SY5Y Cells

Myosin translocation in retinal pericytes during free-radical induced apoptosis

Vascular pathologies induced by ischemia/reperfusion involve the production of reactive oxygen species (ROS) that in part cause tissue injury. The production of ROS that occurs upon reperfusion activates specific second messenger pathways. In diabetic retinopathy there is a characteristic loss of the microvascular pericyte. Pericytes are more sensitive than endothelial cells to low concentrations of ROS, such as hydrogen peroxide (H(2)O(2)) when tested in vitro. Whether the pericyte loss is due to toxic cell death triggered by the noxious H(2)O(2) or apoptosis, due to activation of specific second messenger pathways, is unknown. During apoptosis, a cell's nucleus and cytoplasm condense, the cell becomes fragmented, and ultimately forms apoptotic bodies. It is generally assumed that apoptosis depends on nuclear signaling, but cytoplasmic morphological processes are not well described. We find that exposing cultured retinal pericytes to 100 microM H(2)O(2) for 30 min leads to myosin heavy chain translocation from the cytosol to the cytoskeleton and a significant decrease in cell surface area. Pericyte death follows within 60-120 min. Exposing cells to 150 mJ/cm(2) ultraviolet radiation, an alternate free radical generating system, also causes pericyte myosin translocation and apoptosis. Proteolytic cleavage of actin is not observed in pericyte apoptosis. 3-aminobenzamide, a pharmacological inhibitor of the cleavage and activation of the DNA-repairing enzyme poly (ADP-ribose) polymerase (PARP) inhibits pericyte apoptosis, and prevents myosin translocation. Deferoxamine, an iron chelator known to interfere with free radical generation, also inhibits pericyte myosin translocation, contractility, and cell death. Myosin translocation to the cytoskeleton may be an early step in assembly of a competent contractile apparatus, which is involved in apoptotic cell condensation. These results suggest that pericyte loss associated with increased free radical production in diabetic retina may be by an apoptotic phenomenon.

Cytosolic calcium dynamics and free radical-induced apoptosis of the endothelial cells

Cytosolic calcium dynamics and free radical-induced apoptosis of the endothelial cells