Time-Dependent Analysis of Plasmalogens in the Hippocampus of an Alzheimer’s Disease Mouse Model: A Role of Ethanolamine Plasmalogen

Plasmalogens are alkenyl-acyl glycerophospholipids and decreased in post-mortem Alzheimer’s disease (AD) brains. The aim of this study is to investigate the time-dependent changes of plasmalogens in the hippocampus of an AD model mouse (J20). Plasmalogen levels at 3, 6, 9, 12 and 15 months were analyzed by liquid-chromatography-targeted-multiplexed-selected-reaction-monitoring-tandem-mass-spectrometry (LC-SRM/MS). Reactive oxygen species (ROS) levels were evaluated using dichlorofluorescein diacetate (DCF-DA). Plasmalogen synthesizing enzyme glycerone-phosphate O-acyltransferase (GNPAT) and late endosome marker Rab7 levels were quantified by Western blotting. GNPAT localization, changes of neuronal and glial cell numbers were evaluated by immunostaining. Compared to wild-type mice (WT), total plasmalogen-ethanolamine, but not plasmalogen-choline levels, were increased at 9 months and subsequently decreased at 15 months in J20 mice. A principal component analysis of plasmalogen-ethanolamine species could separate WT and J20 mice both at 9 and 15 months. Both GNPAT and Rab7 protein were increased in J20 mice at 9 months, whereas GNPAT was decreased at 15 months. ROS levels were increased in J20 mice except for 9 months. Our results suggest that increased plasmalogen-ethanolamine could counteract ROS levels and contribute to the phagocytosis process in J20 mice at 9 months. Such results might indicate a transient protective response of plasmalogen-ethanolamine in AD conditions.

Trichlorophenyl-benzoxime induces apoptosis in human colon carcinoma cells via activation of mitochondria dependent pathway

Purpose: To determine the apoptotic effect of trichlorophenyl-benzoxime (TCPB) on colorectal cancer (CRC) cells, and to elucidate the mechanism of action. Methods: Colon carcinoma cell lines (DLD-1 and HT-29) were used in this study. The cells were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10 % fetal bovine serum (FBS) and 1 % penicillin/streptomycin at 37 ˚C in an atmosphere of 5 % CO2 and 95 % air. When the cells attained 60 - 70 % confluency, they were treated with serum-free medium and graded concentrations of TCPB (1.0 – 6.0 μM) for 24 h. Cell viability and apoptosis were assessed using 3-(4, 5-dimethylthiazol-2-yl) 2, 5-diphenyltetrazolium bromide (MTT) and flow cytometric assays, respectively. Western blotting and 2', 7' dichlorofluorescein diacetate (DCFH DA) assays were used for the determination of expression levels of apoptotic proteins, and levels of reactive oxygen species (ROS), respectively. Results: Treatment of DLD-1 and HT-29 cells with TCPB led to significant and dose-dependent reductions in their viability, as well as significant and dose-dependent increases in the number of apoptotic cells (p < 0.05). Treatment of HT-29 cells with TCPB led to significant increases in the population of cells in the G0/G1 phase, but significant reduction of cell proportion in S and G2/M phases (p < 0.05). It also significantly and dose-dependently upregulated the expressions of caspase-3 and bax, down-regulation of the expression of bcl-2 (p < 0.05). TCPB treatment upregulated the expressions of p53, cytochrome c (cyt c), procaspase-3, and procaspase-9, but down-regulated the expression of pAkt dose-dependently (p < 0.05). The expression of Akt in HT-29 cells was not significantly affected by TCPB (p > 0.05). However, TCPB significantly enhanced the cleavage of PARP1, and significantly and dose-dependently increased the levels of ROS in HT-29 cells (p < 0.05). Conclusion: These results suggest that TCPB exerts apoptotic effect on CRC cells via activation of mitochondria-dependent pathway, and thus can be suitably developed for the management of colon cancer.

Role of miR-134 in angiotensin II-induced vascular cell pathological changes in atherosclerosis

Purpose: To investigate the role of miR-134 in vascular smooth muscle cell dysfunction-related cardiovascular disease. Methods: The effect of miR-134 was evaluated after human aortic smooth muscle cells (HASMCs) were transfected with miR-134 mimics. The expression levels of p-Akt, mechanistic target of rapamycin (mTOR), cleaved caspase-3, p53, and β-actin were evaluated by immunoblotting. Terminal deoxynucleotidyl transferase dUTP nick-end labeling was used to measure cell apoptosis. Reactive oxygen species levels were assayed by fluorescence microscopy after staining with 2’,7’– dichlorofluorescein diacetate. Results: Angiotensin II treatment induced miR-134 expression and Akt/mTOR activation, and inhibited cell viability in HASMCs (p < 0.01). Co-treatment with miRNA-134 reversed Ang II-induced HASMC dysfunction (p < 0.01). Overexpression of miR-134 is protective in Ang II-induced oxidative stress and apoptosis via the Akt/mTOR pathway (p < 0.05). Conclusion: MicroRNA-134 in HASMCs is a potential therapeutic target for preventing Ang II-induced cardiac dysfunction via modulating Akt/mTOR pathway.

MiR-122 Participates in Oxidative Stress and Apoptosis in STZ-Induced Pancreatic β Cells by Regulating PI3K/AKT Signaling Pathway

At present, there are few reports concerning the relationship between miR-122 and diabetes. In addition, the effect of miR-122 on streptozotocin- (STZ-) induced oxidative damage in INS-1 cells remains unclear. The present study aimed to investigate the role and modulatory mechanisms involving miR-122 in diabetes. STZ was used to induce INS-1 cell damage. Reverse transcription-quantitative PCR was used to investigate the expression of miR-122. A TUNEL cell apoptosis detection kit was used to detect apoptosis. Intracellular ROS levels were determined using dichlorofluorescein-diacetate. The activities of insulin secretion, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-px) were measured using ELISA kits. Western blotting was used to measure the expression levels of Bax, Bcl-2, PI3K, p-PI3K, caspase-3 and caspase-9, cleaved-caspase-3 and cleaved-caspase-9, AKT, and p-AKT. Then, LY294002 (LY, PI3K inhibitor) was used to treat INS-1 cells, and oxidative stress and apoptosis were measured. The results showed that STZ-induced inhibitory effects on insulin secretion were mitigated by miR-122 inhibitor, and the activities of SOD, CAT, and GSH-px were also increased. Furthermore, miR-122 inhibitor inhibited apoptosis and oxidative stress in STZ-induced INS-1 cells. Finally, the addition of LY increased insulin levels; reduced the activities of SOD, CAT, and GSH-px; and promoted apoptosis in STZ-induced INS-1 cells. In conclusion, interference with miR-122 can inhibit oxidative stress and apoptosis in STZ-induced INS-1 cells, involving a mechanism of action related to the PI3K/AKT pathway.

Analysis and Optimization of Conditions for the Use of 2′,7′-Dichlorofluorescein Diacetate in Cultured Hepatocytes

Numerous liver pathologies encompass oxidative stress as molecular basis of disease. The use of 2′,7′-dichlorodihydrofluorescein-diacetate (DCFH2-DA) as fluorogenic redox probe is problematic in liver cell lines because of membrane transport proteins that interfere with probe kinetics, among other reasons. The properties of DCFH2-DA were analyzed in hepatocytes (HepG2, HepaRG) to characterize methodological issues that could hamper data interpretation and falsely skew conclusions. Experiments were focused on probe stability in relevant media, cellular probe uptake/retention/excretion, and basal oxidant formation and metabolism. DCFH2-DA was used under optimized experimental conditions to intravitally visualize and quantify oxidative stress in real-time in HepG2 cells subjected to anoxia/reoxygenation. The most important findings were that: (1) the non-fluorescent DCFH2-DA and the fluorescent DCF are rapidly taken up by hepatocytes, (2) DCF is poorly retained in hepatocytes, and (3) DCFH2 oxidation kinetics are cell type-specific. Furthermore, (4) DCF fluorescence intensity was pH-dependent at pH < 7 and (5) the stability of DCFH2-DA in cell culture medium relied on medium composition. The use of DCFH2-DA to measure oxidative stress in cultured hepatocytes comes with methodological and technical challenges, which were characterized and solved. Optimized in vitro and intravital imaging protocols were formulated to help researchers conduct proper experiments and draw robust conclusions.

Beyond Microcystins: Cyanobacterial Extracts Induce Cytoskeletal Alterations in Rice Root Cells

Microcystins (MCs) are cyanobacterial toxins and potent inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A), which are involved in plant cytoskeleton (microtubules and F-actin) organization. Therefore, studies on the toxicity of cyanobacterial products on plant cells have so far been focused on MCs. In this study, we investigated the effects of extracts from 16 (4 MC-producing and 12 non-MC-producing) cyanobacterial strains from several habitats, on various enzymes (PP1, trypsin, elastase), on the plant cytoskeleton and H2O2 levels in Oryza sativa (rice) root cells. Seedling roots were treated for various time periods (1, 12, and 24 h) with aqueous cyanobacterial extracts and underwent either immunostaining for α-tubulin or staining of F-actin with fluorescent phalloidin. 2,7-dichlorofluorescein diacetate (DCF-DA) staining was performed for H2O2 imaging. The enzyme assays confirmed the bioactivity of the extracts of not only MC-rich (MC+), but also MC-devoid (MC−) extracts, which induced major time-dependent alterations on both components of the plant cytoskeleton. These findings suggest that a broad spectrum of bioactive cyanobacterial compounds, apart from MCs or other known cyanotoxins (such as cylindrospermopsin), can affect plants by disrupting the cytoskeleton.

The effect of chronic dosing and p53 status on the genotoxicity of pro-oxidant chemicals in vitro

In this study, we have studied the cytotoxicity and genotoxic potency of 3 pro-oxidants; H2O2, menadione and KBrO3 in different dosing scenarios, namely acute (1-day dosing) and chronic (5-days). For this purpose, relative population doubling (RPD%) and mononucleated micronucleus (MN) test were used. TK6 cells and NH32 were employed in in vitro experiments. In the study, the total acute dose was divided into 5 days for each prooxidant chemicals by dose fractionation (1/5th per day) method. Acute dosing was compared to chronic dosing. The oxidative stress caused by the exposure of cells with pro-oxidant chemicals to the cells was determined by an optimized 2′,7′-dichlorofluorescein diacetate (DCFHDA) test method. The antioxidant levels of the cell lines were altered with buthionine sulfoxide (BSO) and N-acetyl cysteine (NAC), and the effect of antioxidant capacity on the MN formation in the cells was observed with this method. In the case of H2O2 and menadione, fractional dosing has been observed to result in lower toxicity and lower genotoxicity. But in the case of KBrO3, unlike the other 2 pro-oxidants, higher MN induction was observed with fractionated doses. DCFHDA test clearly demonstrated ROS induction with H2O2 and menadione but not with KBrO3. Unexpectedly, DCFHDA test demonstrated that KBrO3 did not cause an increase ROS levels in both acute and chronic dosing, suggesting an alternative ROS induction mechanism. It was also observed that, treatment with BSO and NAC, caused increasing and decreasing of MN fold change respectively, allowing further ROS specific mechanisms to be explored. Hence, dose fractionation expectedly caused less MN, cytotoxicity and ROS formation with H2O2 and menadione exposure, but not with KBrO3. This implies a unique mechanism of action for KBrO3 induced genotoxicity. Chronic dosing in vitro may be a valuable approach allowing better understanding of how chemicals damage DNA and pose human hazards.

Andrographis paniculata and Its Bioactive Diterpenoids Against Inflammation and Oxidative Stress in Keratinocytes

Andrographis paniculata was widely used in traditional herbal medicine to treat various diseases. This study explored the potential anti-aging activity of Andrographis paniculata in cutaneous cells. Human, adult, low calcium, high temperature (HaCaT) cells were treated with methanolic extract (ME), andrographolide (ANDRO), neoandrographolide (NEO), 14-deoxyandrographolide (14DAP) and 14-deoxy-11,12-didehydroandrographolide (14DAP11-12). Oxidative stress and inflammation were induced by hydrogen peroxide and lipopolysaccharide/TNF-α, respectively. Reactive oxygen species (ROS) production was measured by fluorescence using a 2′,7′-dichlorofluorescein diacetate (DCFH-DA) probe and cytokines were quantified by ELISA for interleukin-8 (IL-8) or reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for tumor necrosis factor-α (TNF-α). Hyaluronic acid (HA) secretion was determined by an ELISA. Our results show a decrease in ROS production and TNF-α expression by ME (5 µg/mL) in HaCaT under pro-oxidant and pro-inflammatory conditions, respectively. ME protected HaCaT against oxidative stress and inflammation. Our findings confirm that ME can be used for the development of bioactive compounds against epidermal damage.

Different Effects of Melatonin on X-Rays-Irradiated Cancer Cells in a Dose-Dependent Manner

The purpose of this study is to investigate the effects of melatonin on the radiosensitivity of HeLa cells. Concentration from 10 to 1000 µM of melatonin was used on HeLa cells before X-rays irradiation (IR). The cellular inactivation effect was analyzed by clonogenic assay, and cell growth was measured by MTT assay at various concentrations. Ten micrometer melatonin promoted the cell-killing effects of IR, while 1000-µM melatonin prevented IR-induced cellular inactivation. Further analysis revealed that 1000-µM melatonin protected the cells from IR-induced reactive oxygen species damage, as the oxidative stress measured by fluorescent microscopy and fluorescence-activated cell sorting using 2,7-dichlorofluorescein diacetate staining. This is further confirmed by melatonin receptor agonist, which has no antioxidant capacity. A 10-µM melatonin, on the contrary, enhanced the cell-killing effects of IR by activating c-Jun NH2-terminal kinase (JNK) signaling. c-Jun NH2-terminal kinase signaling activation was indicated by Western blot of phosphorylated JNK. We used JNK inhibitor to further confirm the involvement of JNK signaling in the cell-killing enhancement of 10-µM melatonin administration. Our results suggest the importance of dose-dependent effects in melatonin application for radiotherapy.

SENSITIVITY OF BREAST CANCER STEM CELLS (CD24-/CD44+) TO DOXORUBICIN IS ASSOCIATED WITH OXIDATIVE STRESS STATUS

Objective: The aim of this study was to analyze the sensitivity of BCSCs to doxorubicin and its association with oxidative stress. Methods: BCSCs (CD24-/CD44+) were treated with doxorubicin every 2 d for 14 d. The determination of cell viability was performed using a trypan blue exclusion assay. The levels of reactive oxygen species (ROS) were measured using a dihydroethidium (DHE) and a 2’,7’-dichlorofluorescein diacetate (DCFH-DA) probes. Manganese superoxide dismutase (MnSOD) mRNA expression and specific activity were also analyzed. Glutathione (GSH) level was measured using Ellman’s method. Results: The viability of the BCSCs decreased after 2 d of treatment with doxorubicin, but started to increase after 8 d. After 8 d of doxorubicin treatment, the ROS level in the BCSCs decreased, while the MnSOD specific activity increased. In addition, the MnSOD mRNA expression and GSH level were suppressed after 8 d of treatment. Conclusion: Doxorubicin treatment induced cytotoxicity after 2 d by increasing the superoxide levels of the BCSCs. After 8 d of treatment, the sensitivity of BCSCs to doxorubicin decreased due to the suppressed oxidative stress from the enhanced antioxidant activity of the MnSOD.