5-aminolevulinic acid induced lipid peroxidation after light exposure on human colon carcinoma cells and effects of alpha-tocopherol treatment

Influence of Polymer Charge on the Localization and Dark- and Photo-Induced Toxicity of a Potential Type I Photosensitizer in Cancer Cell Models

A current trend within photo-dynamic therapy (PDT) is the development of molecular systems targeting hypoxic tumors. Thus, type I PDT sensitizers could here overcome traditional type II molecular systems that rely on the photo-initiated production of toxic singlet oxygen. Here, we investigate the cell localization properties and toxicity of two polymeric anthracene-based fluorescent probes (neutral Ant-PHEA and cationic Ant-PIm). The cell death and DNA damage of Chinese hamster ovary cancer cells (CHO-K1) were characterized as combining PDT, cell survival studies (MTT-assay), and comet assay. Confocal microscopy was utilized on samples incubated together with either DRAQ5, Lyso Tracker Red, or Mito Tracker Deep Red in order to map the localization of the sensitizer into the nucleus and other cell compartments. While Ant-PHEA did not cause significant damage to the cell, Ant-PIm showed increased cell death upon illumination, at the cost of a significant dark toxicity. Both anthracene chromophores localized in cell compartments of the cytosol. Ant-PIm showed a markedly improved selectivity toward lysosomes and mitochondria, two important biological compartments for the cell’s survival. None of the two anthracene chromophores showed singlet oxygen formation upon excitation in solvents such as deuterium oxide or methanol. Conclusively, the significant photo-induced cell death that could be observed with Ant-PIm suggests a possible type I PDT mechanism rather than the usual type II mechanism.

Ruthenium porphyrin-induced photodamage in bladder cancer cells

Photodynamic therapy (PDT) is a noninvasive treatment for solid malignant and flat tumors. Light activated sensitizers catalyze photochemical reactions that produce reactive oxygen species which can cause cancer cell death. In this work we investigated the photophysical properties of the photosensitizer ruthenium(II) porphyrin (RuP), along with its PDT efficiency onto rat bladder cancer cells (AY27). Optical spectroscopy verified that RuP is capable to activate singlet oxygen via blue and red absorption bands and inter system crossing (ISC) to the triplet state. In vitro experiments on AY27 indicated increased photo-toxicity of RuP (20μM, 18h incubation) after cell illumination (at 435nm), as a function of blue light exposure. Cell survival fraction was significantly reduced to 14% after illumination of 20μM RuP with 15.6J/cm(2), whereas the "dark toxicity" of 20μM RuP was 17%. Structural and morphological changes of cells were observed, due to RuP accumulation, as well as light-dependent cell death was recorded by confocal microscopy. Flow cytometry verified that PDT-RuP (50μM) triggered significant photo-induced cellular destruction with a photoxicity of (93%±0.9%). Interestingly, the present investigation of RuP-PDT showed that the dominating mode of cell death is necrosis. RuP "dark toxicity" compared to the conventional chemotherapeutic drug cisplatin was higher, both evaluated by the MTT assay (24h). In conclusion, the present investigation shows that RuP with or without photoactivation induces cell death of bladder cancer cells.

Dietary supplementation with 5-aminolevulinic acid modulates growth performance and inflammatory responses in broiler chickens

The objective of this study was to investigate the effect of dietary supplementation with 5-aminolevulinic acid (5-ALA) on the immune system, inflammatory response, and growth performance of broiler chickens. The levels of cluster of differentiation 3 (CD3) mRNA in the spleens of chickens gradually increased with dietary 5-ALA concentration, while the expression levels of interleukin (IL)-2 decreased. Mitogen-induced proliferation of splenic mononuclear cells and blood mononuclear cell phagocytosis in chickens fed 0.001 and 0.01% 5-ALA-supplemented diets were significantly greater than in chickens fed a basal diet (control). Plasma thiobarbituric acid reactive substance (TBARS) concentration gradually increased along with 5-ALA supplement concentration. These results provide the first evidence that the use of dietary 0.001 and 0.01% 5-ALA supplementation induces the T-cell immune system via mild oxidative stress in chickens. Three hours after Escherichia coli lipopolysaccharide-induced immune stimulation, the levels of mRNA encoding pro-inflammatory cytokines, such as IL-6 and tumor necrosis factor-like ligand 1A (TL1A), in chickens fed a 0.001% 5-ALA-supplemented diet were significantly lower than those in chickens exposed to other treatments. The plasma caeruloplasmin concentration in chickens fed a 0.001% 5-ALA-supplemented diet was significantly lower than in controls or in chickens fed diets supplemented with other concentrations of 5-ALA 24 h after injection of LPS. In addition, BW at 21 and 50 d of age was significantly higher in chickens fed a 0.001% 5-ALA-supplemented diet than in control chickens. The findings suggest that supplementation of diets with 0.001% 5-ALA could prevent the catabolic changes induced by immunological stimulation. These results show that 5-ALA might be useful as an immunomodulator to stimulate T-cells via mild oxidative stress in growing broiler chickens, thereby improving the growth performance.

Cytoprotective effect of Artemisia capillaris fractions on oxidative stress-induced apoptosis in V79 cells

The objectives of this study were to determine the effects of Artemisia capillaris on the viability, antioxidant status, and cytoprotective against oxidative stress induced by hydrogen peroxide in V79 cells. Pretreatment with ethyl acetate fraction increased 363% cell viability compared to the positive control (PC). The ethyl acetate fraction of A. capillaris scavenged intracellular reactive oxygen species (ROS) and increased the activities of cellular antioxidant enzymes like superoxide dismutase (SOD), glutathione peroxidase (GSH-px), and catalase (CAT), and also increased glutathione (GSH) content. It thereby prevented lipid peroxidation which was demonstrated by the inhibition of the formation of thiobarbituric acid reactive substance (TBARS). Furthermore, ethyl acetate fraction reduced the apoptotic cells and cell cycle arrest at G2/M phase induced by H(2)O(2). These findings suggest that A. capillaris ethyl acetate fraction protected V79 cells against H(2)O(2) damage, by enhancing the antioxidative activity.

The practicalities of photodynamic therapy in acne vulgaris

A staple clinical skill in a dermatologist's repertoire is the ability to treat acne vulgaris effectively. Light-based therapies such as photodynamic therapy (PDT) widen the therapeutic options available for acne. Numerous review articles have agreed on the answer to core questions such as: 'Does PDT work?' and 'Which acne lesions respond best to PDT?' They conclude that PDT is especially useful in inflammatory acne and may be superior to light therapy alone. This literature review seeks to offer guidance regarding treatment-specific queries about the photosensitizer, route of administration, treatment intervals, light sources and patient selection. Ovid Medline, PubMed and EMBASE database searches were executed between January 2007 and March 2008. Due to the scarcity of data, all five randomized trials, four of which were at least investigator blinded and controlled, 12 open clinical studies, two case reports and two abstracts published in English were considered. Four hundred and nineteen patients were recruited. As the quality of the data was suboptimal in a significant number of articles, the conclusions are drawn in very broad strokes: topical short-contact (90 min or less) 5-aminolaevulinic acid or methyl aminolaevulinate using a noncoherent light source at 2-4-week intervals for a total of two to four treatments produces the greatest clinical effect. Papulopustular acne is more responsive and all Fitzpatrick skin types are eligible. However, patients with skin types I-III have a reduced risk of postinflammatory hyperpigmentation seen in darker skin types. These treatment parameters demonstrate a good side-effect profile resulting in acne remission for at least 3 months to a year in a relatively cost-effective manner. Well-designed nonsplit-face randomized controlled trials would offer further guidance, especially for queries surrounding the light source and illumination schemes.

Antiserum detection of reactive carbonyl species-modified DNA in human colonocytes

Polyunsaturated fats have been linked to occurrences of sporadic colon cancer. One possible cause may be degradation of polyunsaturated fats during cooking, resulting in multiple reactive carbonyl species (RCS) that can damage nuclear DNA and proteins, particularly in rapidly dividing colon crypt cells. This study describes a novel antiserum against RCS-modified DNA, with apparent order of reactivity to DNA modified with 4-hydroxy-trans-2-nonenal > glyoxal > acrolein > crotonaldehyde > malondialdehyde; some reactivity was also observed against conjugated Schiff base-type structures. Anti-(RCS-DNA) antiserum was successfully utilised to demonstrate formation of RCS-DNA in a human colon cell model, exposed to RCS insult derived from endogenous and exogenous lipid peroxidation sources. Further utilisation of the antiserum for immunohistochemical analysis confirmed RCS-modified DNA in crypt areas of 'normal' colon tissue. These results fully support a potential role for dietary lipid peroxidation products in the development of sporadic colon cancer.

On the cytotoxicity and status of oxidative stress of two novel synthesized tri-aza macrocyclic diamides as studied in the V79 cell lines

Two tri-aza macrocycles as diamide derivatives of macrocyclic compounds possess a hydrophilic cavity surrounded by hydrophobic ring, which enables them to diffuse cell membrane and interfere with different living systems. In this study, we comparatively evaluated cytotoxicity effects of tri-aza dibenzo sulfoxide (TSD) and dibenzo sulfide (TTS) macrocyclic diamides in a range of doses (0.5-8mM) and the role of oxidative stress in V79 cell culture. We assessed the effects of these substances on ROS level, cellular viability, apoptosis events, activity of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), and on some macromolecules' oxidative damage end-products: malondialdehyde (MDA), dityrosine, and 8-hydroxy-deoxyguanosine (8-OH-dG) that were assessed by spectrometry and HPLC methods. Both compounds revealed cytotoxicity effects on cell culture particularly at doses >1mM after 24-h incubation. They decreased cellular viability and significantly promoted ROS generation, increased enzyme activities, and enhanced oxidative damages in which TSD was more effective. Treatment of cells with each compound alone increased significantly the percent of apoptotic events at 2 and then 4mM. Co-treatment with alpha-tocopherol (alpha-TCP) drastically reduced these events. Cells' exposure with mixture of 30 microM alpha-tocopherol and 8mM of each compound exerted significant decrease in the levels of ROS, enzyme activities, and oxidative damage biomarkers. As conclusion, our study documented the oxidative radical forming ability of the studied compounds and further strengthened the documentation of their cytotoxicity effects through lipids, proteins and DNA oxidation damages.

Oxidative response of rat lung tissue after crown ethers exposure and the effects of alpha-tocopherol treatment

BACKGROUND

Ionophoric properties of crown ethers enable them ideally to transport across membranes and interfere with different living systems. We studied cytotoxicity effects of 18-crown-6 and 15-crown-5 and the role of oxidative stress in rat lung tissue culture.

METHODS

We assayed the effects of these crown ethers in a range of doses (0.1 to 2 mmol/l) on lipids and proteins oxidative damages end products; malondialdehyde (MDA) and dityrosine and on the activity of antioxidant enzymes; superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), in rat lung tissue culture by spectrometry and HPLC.

RESULTS

Both compounds significantly increased the levels of MDA, dityrosine and enzyme activities at doses >0.5 mmol/l after 48-h incubation in the lung tissue, representing promotion of ROS generation with respect to control. These effects were more considerable for 18-crown-6 than 15-crown-5. Treatment of lung tissue with 30 microm of alpha-tocopherol in addition to 2 mmol/l of crown ethers showed significant decrease on the levels of enzyme activities, MDA and dityrosine.

CONCLUSION

We showed the oxidative radicals forming ability of crown ethers as documented in their toxicity effects through lipid and proteins oxidation damages.

Closely related colon cancer cell lines display different sensitivity to polyunsaturated fatty acids, accumulate different lipid classes and downregulate sterol regulatory element-binding protein 1

N-6 polyunsaturated fatty acids (PUFAs) may be associated with increased risk of colon cancer, whereas n-3 PUFAs may have a protective effect. We examined the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid and arachidonic acid on the colon carcinoma cell lines SW480 derived from a primary tumour, and SW620 derived from a metastasis of the same tumour. DHA had the strongest growth-inhibitory effect on both cell lines. SW620 was relatively more growth-inhibited than SW480, but SW620 also had the highest growth rate in the absence of PUFAs. Flow cytometry revealed an increase in the fraction of cells in the G2/M phase of the cell cycle, particularly for SW620 cells. Growth inhibition was apparently not caused by increased lipid peroxidation, reduced glutathione or low activity of glutathione peroxidase. Transmission electron microscopy revealed formation of cytoplasmic lipid droplets after DHA treatment. In SW620 cells an eightfold increase in total cholesteryl esters and a 190-fold increase in DHA-containing cholesteryl esters were observed after DHA treatment. In contrast, SW480 cells accumulated DHA-enriched triglycerides. Arachidonic acid accumulated in a similar manner, whereas the nontoxic oleic acid was mainly incorporated in triglycerides in both cell lines. Interestingly, nuclear sterol regulatory element-binding protein 1 (nSREBP1), recently associated with cell growth regulation, was downregulated after DHA treatment in both cell lines. Our results demonstrate cell-specific mechanisms for the processing and storage of cytotoxic PUFAs in closely related cell lines, and suggest downregulation of nSREBP1 as a possible contributor to the growth inhibitory effect of DHA.

Cytotoxicity and the levels of oxidative stress parameters in WI38 cells following 2 macrocyclic crown ethers treatment

BACKGROUND

Crown ethers as macrocyclic polyethers possess a hydrophilic cavity surrounded by hydrophobic ring which enable them to diffuse cell membrane. We evaluated cytotoxicity effects of 15-crown-5 and 18-crown-6 and the role of oxidative stress in WI38 cells culture.

METHODS

The effect of these ethers in a range of doses (0.1 to 2 mmol/l) on the activity of antioxidant enzymes; superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), and on some macromolecules oxidative damages end products; malondialdehyde (MDA) and dityrosine were assessed by spectrometry and HPLC methods.

RESULTS

Both compounds markedly inhibited the viability of cells with respect to control particularly at doses >0.5 mmol/l after 24- or 48 h incubation. The survivals of cells were measured using MTT assay. They lowered cell's viability and significantly promoted ROS generation, increased enzyme activities and enhanced oxidative damages in which 18-crown-6 was more effective. Treating cells with 30 microm of alpha-tocopherol in addition to 2 mmol/l of crown ethers showed significant decrease on the levels of ROS, enzyme activities, MDA and dityrosine.

CONCLUSION

We document the oxidative radicals forming ability of the studied crown ethers and further strengthens the documentation of their cytotoxicity effects through lipid and proteins oxidation damages.

ALA-induced porphyrin formation and fluorescence in synovitis tissue In-vitro and in vivo studies

The synovial inflammatory process in rheumatoid arthritis (RA) is accompanied by massive tumor-like proliferation and activation of the connective stroma. These abnormal cells actively invade and destroy the peri-articular bone and cartilage at the margins of joints where synovium and bone are attached. There is still a lack of minimally invasive synovectomy methods, which might be suitable for the smaller joints. Unfortunately, these joints are usually involved in the disease. Photodynamic therapy has been evaluated as a possible treatment modality for RA synovitis. The present study describes the differences of 5-aminolevulinic acid (5-ALA) and 5-ALA ester-induced protoporphyrin IX (PpIX) production in cell cultures obtained from patients with RA, osteoarthritis (OA) and human sarcoma cell line (HS 192.T) and in a collagen-induced arthritis model in rats. The incubation of cells with hexyl aminolevulinate (HAL) induced the same amount of fluorescence as 5-ALA and methyl aminolevulinate (MAL) at about a 100-fold lower concentration. Incubation with HAL-induced accumulation of at least twice as much porphyrins in RA- and HS 192.T-cells than 5-ALA and MAL in OA-cells. Similar levels of porphyrins were accumulated in RA and the malignant cells. In vivo, intra-articular application of 5-ALA induced a significant porphyrin accumulation in synovitis tissue as measured by in situ fluorescence spectroscopy. In contrast to our in vitro results and other reports, we could not detect enhanced fluorescence after application of up to 0.1mg HAL.

Cell specific effects of polyunsaturated fatty acids on 5-aminolevulinic acid based photosensitization

The purpose of this study was to examine whether the dietary components n-6 and n-3 polyunsaturated fatty acids (PUFAs) may potentiate the effect of photodynamic therapy (PDT) in human cancer cell lines by enhancing the lipid peroxidation. The effects of the porphyrin precursor 5-aminolevulinic acid (5-ALA) and light (320 < lambda < 440 nm, 33 W m(-2)), with or without docosahexaenoic acid (DHA) or arachidonic acid (AA), were tested in the colon carcinoma cell lines SW480 and WiDr, the glioblastoma cell line A-172 and the lung adenocarcinoma cell line A-427. The production of endogenous protoporphyrin IX (PpIX) varied substantially between the cell lines and was approximately 4-fold higher in WiDr as compared with SW480. Cell killing by 5-ALA-PDT also varied between the cell lines, but without clear correlation with PpIX levels. Treatment with DHA or AA (10 or 70 microM, 48 or 72 h) in combination with 5-ALA-PDT (1 or 2 mM) enhanced the cytotoxic effect in A-172 and A-427 cells, but not in SW480 and WiDr cells. While 5-ALA-PDT alone increased the lipid peroxidation in A-172 and WiDr cells only, 5-ALA-PDT plus PUFAs increased the lipid peroxidation substantially in all four cell lines. Interestingly, alpha-tocopherol (50 microM, 48 h) strongly reduced lipid peroxidation after all treatments in all cell lines, while cytotoxicity was only reduced substantially in A-427 cells. This demonstrates that induction of lipid peroxidation is not a general mechanism responsible for the cytotoxicity of 5-ALA-PDT, although it may be important in cell lines with an inherent sensitivity to lipid peroxidation products. Thus, the mechanisms of cell growth inhibition/cell killing by PDT are complex and cell specific.

Cellular damage to human hepatocytes through repeated application of 5-aminolevulinic acid

BACKGROUND/AIMS

5-Aminolevulinic acid (ALA), a precursor of porphyrins is used for photodynamic diagnosis and therapy within topical or systemic applications. A potential toxic effect on the human liver is of major interest and therefore we investigated the impact of a repeated application of ALA without illumination on cultures of human hepatocytes.

METHODS

After ALA treatment of hepatocytes in vitro the porphyrin synthesis, albumin secretion, liver-specific enzyme release, and malondialdehyde levels were determined. In order to reduce levels of reactive oxygen substances, mannitol and the antioxidant enzymes superoxide dismutase and catalase were supplemented.

RESULTS

Porphyrin biosynthesis by human hepatocytes in vitro was repeatedly stimulated by ALA (0.001-1.0 mM), which was indicated by an accumulation of protoporphyrin IX. A repetitive treatment (up to four times) of hepatocytes with ALA resulted in an impairment of the hepatic function and viability, depending on the ALA concentration (0.1-1.0 mM) and frequency of application (2-3 times). This was also accompanied by increased malondialdehyde levels indicating enhanced lipid peroxidation. Only superoxide dismutase was able to reduce cellular damage and prevent specific function.

CONCLUSIONS

Repeated, not single, ALA treatment without illumination may cause deleterious effects to the liver, which are mediated by oxygen radicals and inhibited by an antioxidant.

Hyperresistance to photosensitized lipid peroxidation and apoptotic killing in 5-aminolevulinate-treated tumor cells overexpressing mitochondrial GPX4

Antitumor photodynamic therapy (PDT) with administered 5-aminolevulinic acid (ALA) is based on metabolism of ALA to protoporphyrin IX (PpIX), which acts as a sensitizer of photo-oxidative damage leading to apoptotic or necrotic cell death. An initial goal of this study was to ascertain how the PpIX-sensitized death mechanism for a breast tumor line (COH-BR1 cells) might be influenced by the conditions of ALA exposure in vitro. Two different treatment protocols were developed for addressing this question: (i) continuous incubation with 1 mM ALA for 90 min; and, (ii) discontinuous incubation, i.e., 15 min with 1 mM ALA followed by 225 min without it. Following exposure to 2 J/cm2 of visible light, cell viability, death mechanism, and lipid hydroperoxide (LOOH) level were evaluated for each protocol using thiazolyl blue, Hoechst staining, and HPLC with electrochemical detection assays, respectively. PpIX was found to sensitize apoptosis when it existed mainly in mitochondria (protocol-1), but necrosis when it diffused to other sites, including plasma membrane (protocol-2). Experiments with a transfectant clone, 7G4, exhibiting approximately 85 times greater activity of the LOOH-detoxifying selenoenzyme GPX4 than parental cells, provided additional information about death mechanism. Located predominantly in mitochondria of 7G4 cells, GPX4 strongly inhibited both LOOH accumulation and apoptosis under protocol-1 conditions, but had no significant effect under protocol-2 conditions. These findings support the hypothesis that LOOHs produced by attack of photogenerated singlet oxygen on mitochondrial membrane lipids play an important early role in the apoptotic death cascade.