Ubiquitin proteasomal system is a potential target of the toxic effects of organophosphorus flame retardant triphenyl phosphate

The consumption of the widely used flame retardant Triphenyl phosphate (TPP) is increasing. It is now frequently detected in the environment and also domestically. Although the possibility of dermal exposure to TPP is quite high, little is known about its potential molecular toxicity mechanisms. In this study, we found that TPP caused cytotoxicity on human skin keratinocytes (HaCaT) and significantly inhibited the proliferation and cell migration in a concentration-dependent manner. Additionally, HaCaT cells were sensitive to TPP-induced apoptosis. Reactive oxygen species production was induced with TPP, which increased the protein carbonylation and lipid peroxidation levels. Moreover, TPP inhibited proteasome activity and increased the accumulation of ubiquitinated proteins. Exposure to TPP significantly increased the HSP90, HSP70, GRP94 and GRP78 protein levels. Overall, our findings indicate that TPP may pose a risk to human health and contribute to the current understanding of the risks of TPP at the molecular level.

Mitochondrial dynamics imbalance and mitochondrial dysfunction contribute to the molecular cardiotoxic effects of lenvatinib

Lenvatinib is a tyrosine kinase inhibitor (TKI) approved for the treatment of resistant differentiated thyroid cancer, advanced renal cell carcinoma, unresectable hepatocellular carcinoma, and endometrial carcinoma. Although it is successful in cancer treatment, it can cause life-threatening side effects such as cardiotoxicity. The molecular mechanism of cardiotoxicity caused by lenvatinib is not fully known. In this study, the molecular mechanism of lenvatinib's cardiotoxicity was investigated focusing on mitochondrial toxicity in the H9c2 cardiomyoblastic cell line. Lenvatinib inhibited cell viability at 48 and 72 h exposure with three selected concentrations (1.25 μM, 5 μM and 10 μM); and inhibited intracellular ATP after 72 h exposure compared to the control group. Mitochondrial membrane potential was decreased after 48 h and did not show significant changes after 72 h exposure. Evaluated with real-time PCR, mitochondrial dynamics (Mfn1, Mfn2, OPA1, DRP1, Fis1) expression levels after lenvatinib treatment significantly changed. Lenvatinib triggered the tendency from fusion to fission in mitochondria after 48 h exposure, and increased both fusion and fission after 72 h. The mtDNA ratio increased after 48 h and decreased after 72 h. ASK1, JNK and AMPKα2 increased. UCP2 showed downregulation, SOD2 level showed upregulation and Cat levels decreased after drug treatment. Nrf1 and Nrf2 also changed concentration-dependently. Protein carbonyl levels increased significantly after lenvatinib treatments indicating oxidative stress. The protein levels of the electron transport chain complexes, LONP1, UCP2, and P21 showed significant differences after lenvatinib treatment. The outcome of our study is expected to be a contribution to the understanding of the molecular mechanisms of TKI-induced cardiotoxicity.

Extended regorafenib treatment can be linked with mitochondrial damage leading to cardiotoxicity

Regorafenib (RGF) has a great success in the treatment of colorectal cancer, gastrointestinal stromal tumours and hepatocellular carcinoma by inhibiting angiogenic, stromal and oncogenic kinases. However, RGF can induce life-threatening cardiotoxicity including hypertension and cardiac ischemia/infarction. The molecular mechanism of the adverse effects has not been elucidated. Mitochondrial dysfunction is one of the major causes of cardiac diseases since cardiac cells highly need ATP for their contractility. Therefore, we aimed to investigate molecular mechanisms of RGF-induced cardiac adverse effects using H9c2 cell model by focusing on mitochondria. Cells were treated with 0-20 μM RGF for 48 and 72 h. According to our results, RGF inhibited cell proliferation and decreased the ATP content of the cells depending on the exposure time and concentration. Loss of mitochondrial membrane potential was also observed at high dose. Mitochondrial fusion/fission genes and antioxidant SOD2 (superoxide dismutase) gene expression levels increased at high doses in both treatments. Mitochondrial DNA content decreased as exposure time and concentration increased. Also, protein expression levels of mitochondrial complex I and V have reduced and stress protein HSP70 level has increased following RGF treatment. Structural abnormalities in mitochondria was seen with transmission electron microscopy at the applied higher doses. Our findings suggest that RGF-induced cardiotoxicity may be associated with mitochondrial damage in cardiac cells.

In vitro assessment of the cytotoxic, genotoxic and oxidative stress effects of the synthetic cannabinoid JWH-018 in human SH-SY5Y neuronal cells

BACKGROUND

JWH-018 was the first synthetic cannabinoid introduced as a legal high and the first of the new generation of novel psychoactive substances that flooded worldwide drug markets. JWH-018 was marketed as "spice," "herbal incense," or "herbal blend," as a popular and legal (at the time) alternative to cannabis (marijuana). JWH-018 is a potent synthetic cannabinoid with considerable toxicity associated with its use. JWH-018 has qualitatively similar but quantitatively greater pharmacological effects than cannabis, leading to intoxications and even deaths. The mechanisms of action of the drug's toxicity require research, and thus, the aim of the present study was to investigate the toxicological profile of JWH-018 in human SH-SY5Y neuronal cells.

METHODS

SH-SY5Y neuronal cells were exposed to increasing concentrations from 5 to 150 μM JWH-018 over 24 h. Cytotoxicity, DNA damage, the apoptotic/necrotic rate, and oxidative stress were assessed following SH-SY5Y exposure.

RESULTS

JWH-018 did not produce a significant decrease in SH-SY5Y cell viability, did not alter apoptotic/necrotic rate, and did not cause genotoxicity in SH-SY5Y cells with 24-h exposure. Glutathione reductase and catalase activities were significantly reduced; however, there was no significant change in glutathione peroxidase activity. Also, JWH-018 treatment significantly decreased glutathione concentrations, significantly increased protein carbonylation, and significantly increased malondialdehyde (MDA) concentrations. For significance, all P < 0.05.

DISCUSSION/CONCLUSION

JWH-018 produced oxidative stress in SH-SY5Y cells that could be an underlying mechanism of JWH-018 neurotoxicity. Additional in vivo animal and human-based studies are needed to confirm our findings.

Higher proteotoxic stress rather than mitochondrial damage is involved in higher neurotoxicity of bortezomib compared to carfilzomib

Proteasome inhibitors have great success for their therapeutic potential against hematologic malignancies. First generation proteasome inhibitor bortezomib induced peripheral neuropathy is considered as a limiting factor in chemotherapy and its second-generation counterpart carfilzomib is associated with lower rates of neurotoxicity. The mitochondrial toxicity (mitotoxicity) hypothesis arises from studies with animal models of bortezomib induced peripheral neuropathy. However, molecular mechanisms are not fully elucidated and the role of mitotoxicity in bortezomib and carfilzomib induced neurotoxicity has not been investigated comparatively. Herein, we characterized the neurotoxic effects of bortezomib and carfilzomib at the molecular level in human neuronal cells using LC-MS/MS analysis, flow cytometry, RT-qPCR, confocal microscopy and western blotting. We showed that bortezomib and carfilzomib affected the human neuronal proteome differently, and bortezomib caused higher proteotoxic stress via protein oxidation, protein K48-ubiquitination, heat shock protein expression upregulation and reduction of mitochondria membrane potential. Bortezomib and carfilzomib did not affect the gene expression levels related to mitochondrial dynamics (optic atrophy 1; OPA1, mitofusin 1; MFN1, mitofusin 2; MFN2, fission 1; FIS1, dynamin-related protein 1; DRP1) and overall mitophagy rate whereas, PINK1/Parkin mediated mitophagy gene expressions were altered with both drugs. Bortezomib and carfilzomib caused downregulation of the contents of mitochondrial oxidative phosphorylation complexes, voltage-dependent anion channel 1 (VDAC1) and uncoupling protein 2 (UCP2) similarly. Our findings suggest that, both drugs induce mitotoxicity besides proteotoxic stress in human neuronal cells and the higher incidence of neurotoxicity with bortezomib than carfilzomib is not directly related to mitochondrial pathways.

Celastrol pretreatment as a therapeutic option against cisplatin-induced nephrotoxicity

Celastrol is a natural bioactive compound extracted from the medicinal plant Tripterygium wilfordii Hook F. It exhibits immunosuppressive, anti-inflammatory, and antioxidant activities. Cisplatin is a commonly used chemotherapeutic drug in the treatment of a wide range of tumors. Although very effective therapeutically, it can cause nephrotoxicity leading to dose reduction or discontinuation of treatment. This study aims to clarify the therapeutic potential of celastrol in cisplatin-induced nephrotoxicity. The possible protective effects of celastrol pretreatment against cisplatin-induced oxidative stress and genotoxicity were investigated. A rat kidney epithelial cell line NRK-52E was pretreated with the desired concentrations of celastrol (200 nM, 100 nM, and 50 nM) for 24 h. The cells were treated with 50 μM cisplatin for a further 24 h to see whether cisplatin caused the same or less toxicity compared to the vehicle control group. Alkaline comet assay was performed for genotoxicity assessment. Genotoxicity evaluation revealed that celastrol caused a statistically significant reduction in DNA damage. Oxidative stress parameters were evaluated by measuring the glutathione (GSH) and protein carbonyl (PC) levels and also by measuring the enzyme activities of glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT) and superoxide dismutase (SOD) enzymes. Celastrol pretreatment increased the GSH content of the cells and ameliorated the protein carbonylation level. Likewise, celastrol pretreatment improved the GR and CAT activities. However, no significant difference was observed in GPx and SOD activities. In the light of these findings, celastrol treatment could be a therapeutic option to reduce cisplatin-induced nephrotoxicity. Further studies are needed for the clarification of its therapeutic potential.

Stanozolol administration combined with exercise leads to decreased telomerase activity possibly associated with liver aging

Anabolic agents are doping substances which are commonly used in sports. Stanozolol, a 17α‑alkylated derivative of testosterone, has a widespread use among athletes and bodybuilders. Several medical and behavioral adverse effects are associated with anabolic androgenic steroids (AAS) abuse, while the liver remains the most well recognized target organ. In the present study, the hepatic effects of stanozolol administration in rats at high doses resembling those used for doping purposes were investigated, in the presence or absence of exercise. Stanozolol and its metabolites, 16‑β‑hydroxystanozolol and 3'‑hydroxystanozolol, were detected in rat livers using liquid chromatography‑mass spectrometry (LC‑MS). Telomerase activity, which is involved in cellular aging and tumorigenesis, was detected by examining telomerase reverse transcriptase (TERT) and phosphatase and tensin homolog (PTEN) expression levels in the livers of stanozolol‑treated rats. Stanozolol induced telomerase activity at the molecular level in the liver tissue of rats and exercise reversed this induction, reflecting possible premature liver tissue aging. PTEN gene expression in the rat livers was practically unaffected either by exercise or by stanozolol administration.

Effects of stanozolol on apoptosis mechanisms and oxidative stress in rat cardiac tissue

Stanozolol is a widely used 17α-alkylated anabolic androgenic steroid (AAS) derivative. Despite stanozolol's adverse effects, its effect on oxidative stress parameters and mitochondrial apoptosis pathway is not clearly defined. In our study, thirty four male Sprague-Dawley rats were divided into 5 groups as control (C), vehicle control (VC), steroid (ST), vehicle control-exercise (VCE), and steroid-exercise (STE). Animals were subcutaneously administered stanozolol 5 mg/kg in steroid groups and propylene glycol 1 ml/kg in the vehicle-control groups. On the 28th day-after sacrification, oxidative stress (MDA, GSH, PC, SOD, CAT) and apoptosis parameters (TUNEL, Cytochrome-c) in cardiac tissue were evaluated. Also, blood vessel morphology of cardiac tissue was evaluated with Verhoeff-van Giesen staining. It has been demonstrated that stanozolol administration triggers apoptosis by using TUNEL assay and cytochrome-c immunohistochemical staining intensity, while this effect is significantly reduced in the presence of exercise. In conclusion, the present study demonstrated that stanozolol administration induces apoptosis with increasing PC and CAT levels, while GSH, MDA and SOD parameters do not reveal any significant change. Exercise has a protective role in stanozolol induced oxidative stress and apoptosis. According to Verhoeff-van Giesen staining results for blood vessel morphology assessment, it has been seen that exercise has a protective role on cardiac blood vessels. This mechanism needs further investigations with long term exposure studies for clarifying possible pathways.

Celastrol ameliorates acetaminophen-induced oxidative stress and cytotoxicity in HepG2 cells

Acetaminophen (APAP) is the most commonly used analgesic and antipyretic drug in the world. However, hepatotoxicity caused by APAP overdose is the most frequent cause of acute liver failure worldwide and oxidative stress involved in the pathogenesis of APAP hepatotoxicity. Celastrol is a natural triterpenoid derived from Tripterygium wilfordii Hook F. that exhibits antioxidant, anti-inflammatory, and antitumor activities. In this study, we aimed to investigate the potential ameliorative effects of celastrol against APAP-induced cytotoxicity and oxidative stress. Human hepatocellular carcinoma cells (HepG2) were incubated with 20 mM of APAP for 24 h and posttreated with 50 nM, 100 nM, or 200 nM of celastrol for a further 24 h. The methylthiazolyldiphenyl-tetrazolium bromide, lactate dehydrogenase, and neutral red uptake assays showed celastrol posttreatments recovered cell viability and cell membrane integrity in a concentration-dependent manner. Celastrol posttreatments exerted a significant increase in the glutathione content and a decrease in the malondialdehyde and protein carbonylation levels. Also, celastrol posttreatments attenuated the APAP-induced oxidative stress by raising glutathione peroxidase, glutathione reductase, and catalase activities. However, superoxide dismutase activity did not change. In conclusion, celastrol treatment may improve cell viability and increase cellular antioxidant defense in HepG2 cells. These results suggest that celastrol may have the potential to ameliorate the APAP-induced oxidative stress and cytotoxicity.

Determination of DNA damage and telomerase activity in stanozolol-treated rats

Anabolic androgenic steroids (AAS) are performance-enhancing drugs commonly abused by atheletes. Stanozolol is a synthetic testosterone-derived anabolic steroid. Although it is well known that AAS have several side-effects, there are only few toxicological studies available on the toxic effects and mechanisms of action of stanozolol. The aim of this study was to investigate the genotoxic effects of stanozolol and to determine its effects on telomerase activity in Sprague-Dawley male rats. For this purpose, 34 male rats were divided into 5 groups as follows: i) the control group (n=5); ii) the propylene glycol (PG)-treated group (n=5); iii) the stanozolol-treated group (n=8); iv) the PG-treated group subjected to exercise (n=8); and v) the stanozolol-treated group subjected to exercise (n=8). PG is used as a solvent control in our study. Stanozolol (5 mg/kg) and PG (1 ml/kg) were injected subcutaneously 5 days/week for 28 days. After 28 days, the animals were sacrificed, and DNA damage evaluation (comet assay) and telomerase activity assays were then performed using peripheral blood mononuclear cells (PBMCs). Telomerase activity was measured by using the TeloTAGGG Telomerase PCR ELISA PLUS kit. The results of this study revealed that stanozolol treatment induced DNA damage, while exercise exerted a protective effect. Stanozolol treatment without exercise stimulation was associated with a significant increase in telomerase activity in the PBMCs.

DNA methylation analysis in rat kidney epithelial cells exposed to 3-MCPD and glycidol

3-Monochloropropane-1,2-diol (3-MCPD) is a well-known food processing contaminant that has been regarded as a rat carcinogen, which is known to induce Leydig-cell and mammary gland tumors in males, as well as kidney tumors in both genders. 3-MCPD is highly suspected to be a non-genotoxic carcinogen. 2,3-Epoxy-1-propanol (glycidol) can be formed via dehalogenation from 3-MCPD. We aimed to investigate the cytotoxic effects of 3-MCPD and glycidol, then to demonstrate the possible epigenetic mechanisms with global and gene-specific DNA methylation in rat kidney epithelial cells (NRK-52E). IC₅₀ value of 3-MCPD was determined as 48 mM and 41.39 mM, whereas IC₅₀ value of glycidol was 1.67 mM and 1.13 mM by MTT and NRU test, respectively. Decreased global DNA methylation at the concentrations of 100 μM and 1000 μM for 3-MCPD and 100 μM and 500 μM for glycidol were observed after 48 h exposure by using 5-methylcytosine (5-mC) ELISA kit. Methylation changes were detected in promoter regions of c-myc and Rassf1a in 3-MCPD and glycidol treated NRK-52E cells by using methylation-specific PCR (MSP), whereas changes on gene expression of c-myc and Rassf1a were observed by using real-time PCR. However, e-cadherin, p16, VHL and p15 genes were unmethylated in their CpG promoter regions in response to treatment with 3-MCPD and glycidol. Alterations in DNA methylation might be key events in the toxicity of 3-MCPD and glycidol.

Evaluation of DNA damage and DNA repair capacity in occupationally lead-exposed workers

Occupational lead (Pb) exposure remains a significant concern for workers in Turkey. Health hazards of Pb exposure have been investigated in various test systems, but results regarding its potential genotoxic effects on exposed populations are contradictory. In this study, a control group and an exposed group were studied, each consisting of 25 male subjects. Blood lead levels (BLLs) were estimated by graphite furnace atomic absorption spectrometry. Genotoxic effects of Pb exposure were studied in leukocytes by comet and challenge assays. The effect of Pb exposure to DNA repair capacity was evaluated following in vitro hydrogen peroxide exposure. Pb-exposed workers had significantly higher BLLs than the control group ( p < 0.01). DNA damage in exposed workers had a significantly higher percentage of DNA in tail than the control group ( p < 0.05). In the challenge assay, it was found that the mean DNA% repair capacity was significantly decreased in Pb-exposed workers ( p < 0.01). The results indicated that occupational Pb exposure is associated with DNA damage and causes decrease in DNA% repair capacity, indicating a potential health concern for occupationally Pb-exposed populations.

Application of a validated LC-MS/MS method for JWH-073 and its metabolites in blood and urine in real forensic cases

Synthetic cannabinoids, which were synthesized to improve the therapeutic effects of cannabis, have become a major issue when they are abused. They have different chemical structures from tetrahydrocannabinol (THC) but similar effects on endocannabinoid receptors. "Spice" named products have more serious side effects than cannabis and can even cause death. These mixtures are prepared by spraying chemicals onto small pieces of herbs and are being dishonestly sold as "natural" and "legal" products over the internet. Their popularity is continuously increasing. Studies on detecting synthetic cannabinoids in biological samples as well as pharmacology and toxicology studies of these chemicals are very limited. A fast, specific and robust method for the detection and quantification of JWH-073, JWH-073 N-butanoic acid, and JWH-073 N-(4-hydroxybutyl) in blood and urine has been developed that uses solid-phase extraction (SPE) followed by UPLC-MS/MS analysis. This method has been validated in terms of its linearity (0.1-50 ng/mL), selectivity, intra-assay and inter-assay accuracy and precision (CV<10%), recovery (75-95%), limits of detection (LODs) (0.08-0.13 ng/mL), and limits of quantification (LOQs) (0.11-0.17 ng/mL). Matrix effects, stability, and process efficiency parameters of this method have also been assessed. This method was applied to 2596 authentic samples received by the Department of Toxicology (Istanbul) in the Presidency of Council of Forensic Medicine (Turkey) between September 1, 2012, and February 28, 2015.

Role of fumonisin B1 on DNA methylation changes in rat kidney and liver cells

CONTEXT

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides (Sacc.) Nirenberg (Nectriaceae) mold that contaminates maize and other agricultural products. Although the effects of FB1 on sphingolipid metabolism are clear, little is known about early molecular changes associated with FB1 carcinogenicity.

OBJECTIVE

Alteration on DNA methylation, as an early event in non-genotoxic carcinogenesis, may play an important role in the mechanism of FB1 toxiciy.

MATERIALS AND METHODS

Dose-related effects of FB1 (1-50 µM for 24 h) on global DNA methylation by using high-performance liquid chromatography with UV-diode array detection (HPLC-UV/DAD) and CpG promoter methylation by methylation-specific PCR (MSP) were performed in rat liver (Clone 9) and rat kidney (NRK-52E) epithelial cells.

RESULTS

Cell viability reduction is 39% and 34% by the XTT test and LDH release in the growth medium is 32% and 26% at 200 µM of FB1 treatment in Clone 9 and NRK-52E cells, respectively. No significant dose-related effects of FB1 on global DNA methylation which ranged from 4 to 5% were observed in both cells compared with controls. Promoter regions of c-myc gene were methylated (>33%) at 10 and 50 µM of FB1 treatment in Clone 9 cells while it was unmethylated in NRK-52E cells. Promoter regions of p15 gene were unmethylated while VHL gene were found to be methylated (>33%) at 10, 25, and 50 µM and 10 and 50 µM of FB1 treatment in Clone 9 and NRK-52E cells, respectively.

DISCUSSION AND CONCLUSION

Alteration in DNA methylation might play an important role in the toxicity of FB1 in risk assessment process.

Investigation on the toxic potential of Tribulus terrestris in vitro

CONTEXT

Tribulus terrestris L. (Zygophyllaceae) has been commonly used to energize, vitalize, and improve sexual function and physical performance in men.

OBJECTIVE

This study investigates the potential cytotoxic and genotoxic, and endocrine disrupting activities of T. terrestris in vitro.

MATERIALS AND METHODS

The whole T. terrestris plant was extracted with water, methanol, and chloroform. The genotoxic potential of T. terrestris extracts at 3-2400 µg/mL was assessed by Comet assay in a rat kidney cell line (NRK-52E) and by Ames assay in Salmonella typhimurium TA98 and TA100 strains. Endocrine disrupting effects of the extracts at concentrations of 0.22-25 000 µg/mL were assessed by YES/YAS assay in Saccharomyces cerevisiae. Cytotoxic activity of the extracts was determined by the MTT test in NRK-52E cells. The different exposure times were used for four tests (3-48 h).

RESULTS

The methanol extract of T. terrestris IC50 value was 160 µg/mL. The other extracts did not show cytotoxic effects. In the Comet and Ames genotoxicity assays, none of the extracts possessed genotoxic activities at concentrations of 0-2400 µg/mL. Only the water extract of T. terrestris induced frame shift mutations after metabolic activation. The water extract also showed estrogenic activity by YES/YAS assay in S. cerevisiae at concentrations ≥27 µg/mL (≥2.6-fold), while the other T. terrestris extracts had anti-estrogenic properties.

CONCLUSION

Tribulus terrestris had estrogenic and genotoxic activities. The study was useful in determining its toxicological effects and the precautions regarding consumption.

Validation of JWH-018 and its metabolites in blood and urine by UPLC-MS/MS: Monitoring in forensic cases

The herbal products referred to as 'Spice' have been used as 'legal alternatives' to cannabis worldwide since 2004. The first synthetic cannabinoid JWH-018 was detected in 'Spice' products in 2008, and has been banned by many legal authorities since the beginning of 2009. In order to prove use of JWH cannabinoids (JWHs), specific and robust methods were needed. We have developed a specific and reliable method for the detection and quantification of JWH-018, JWH-018 N-pentanoic acid, and JWH-018 N-(5-hydroxypentyl) in blood and urine using solid-phase extraction followed by UPLC-MS/MS analysis. The method has been validated in terms of linearity (0.1-50ng/mL), selectivity, intra-assay and inter-assay accuracy and precision (CV<15%), recovery (85-98%), limits of detection (LOD) (0.08-0.14ng/mL), and quantification (LOQ) (0.10-0.21ng/mL). Matrix effects, stability, and process efficiency were also assessed. The method has been applied to 868 authentic samples received by the Department of Chemistry (Istanbul) in the Council of Forensic Medicine of the Ministry of Justice.

Genetic variations in the xenobiotic-metabolizing enzymes CYP1A1, CYP1A2, CYP2C9, CYP2C19 and susceptibility to colorectal cancer among Turkish people

Cytochrome P450 (CYP) enzymes are genetically polymorphic and play key roles in the metabolism of xenobiotics. Colorectal cancer (CRC) is one of the most common malignant tumors in Turkey as well as in the world. In this study, it was aimed both to evaluate the effects of CYP variants on the susceptibility to CRC and to predict the individual response of the Turkish people to xenobiotics metabolized by CYP enzymes. For that, we assessed the association of CYP1A1, CYP1A2, CYP2C9, and CYP2C19 polymorphisms in patients with CRC in the Turkish population through a case-control study. Distributions of the variants were determined in 104 patients with CRC and 183 healthy volunteers. As results, CYP1A1 6235T/C was significantly associated with CRC risk (odds ratio [OR]=2.53; 95% confidence interval [CI]=0.99-6.45; p=0.046). In a haplotype-based analysis, CYP1A1 haplotype C6235-A2455 might be associated with the development of CRC (OR=2.70; 95% CI=0.58-5.90; p=0.046). We believe that the findings are the first results of CYP allele distributions in the Turkish population and provide an understanding of the epidemiological studies that correlate therapeutic approaches and etiology of CRC especially in Turkish patients.

Ochratoxin A in dried grapes and grape-derived products in Turkey

Ochratoxin A (OTA) is a naturally occurring mycotoxin and widespread food contaminant which results in a probable human exposure. A total of 85 samples (50 dried grapes, 10 grape juices and 25 pekmez (boiled and concentrated grape juices) were collected from different supermarkets and traditional bazaars in Istanbul during 2008-2009. An analytical method based on immuno-affinity column for clean-up and high-performance liquid chromatography equipped with fluorescence detection was used to determine the OTA. Contamination frequencies were 8%, 20% and 88% with mean concentrations of positive samples of 1.15, 1.40 and 2.04 µg/kg for dried grapes, grape juices and pekmez samples, respectively. These levels were lower than the maximum levels as set by the European Commission (EC). However, 12 of 25 pekmez samples had higher levels than permitted by the European Union (EU) for safe consumption.

Associations between the functional polymorphisms in the ABCB1 transporter gene and colorectal cancer risk: a case-control study in Turkish population

Colorectal cancer is among the most common cancer types in the world and its etiology involves the interaction of genetic and environmental factors. ABCB1 is highly expressed in the apical surface of colonic epithelial cells and acts as an efflux pump by transporting toxic endogenous substances, drugs and xenobiotics out of cells. ABCB1 polymorphisms may either change its protein expression or alter its function. Several studies have reported a possible association between ABCB1 variants and colorectal cancer, but no consistent conclusion has been arrived at. Therefore, we aimed to investigate the relationship between colorectal cancer and the functional common variants of ABCB1 (1236C > T; 2677G > T/A; 3435C > T). The distributions of the variants were determined in 103 patients with colorectal cancer and 150 healthy volunteers using polymerase chain reaction-restriction fragment length polymorphism methods. ABCB1 1236C > T was statistically significantly associated with colorectal cancer risk (OR, odd ratio = 1.91; 95% CI, confidence interval = 1.09-3.35; p = 0.034). In haplotype-based analysis, the proportion of individuals with the ABCB1 haplotype C1236-G2677-T3435 was significantly more common in patients than in controls (OR = 11.96; 95% CI = 2.59-55.32; p = 0.0004). We believe that the findings may be beneficial to the development of efficacious preventive strategies and therapies for colorectal cancer.

Influence of the functional polymorphisms in the organic anion transporting polypeptide 1B1 in the susceptibility to colorectal cancer

Colorectal cancer is an important cause of death throughout the world, and its etiology involves the interaction of genetic and environmental factors. Transporter proteins are important in protecting organs from xenobiotics or toxins. Organic anion-transporting polypeptide 1B1 (OATP1B1) plays role in hepatic uptake and clearance of albumin-bound amphipathic organic compounds, including endogen substances, drugs, or xenobiotics. The SLCO1B1 gene expressing OATP1B1 is highly polymorphic. Up to now, SLCO1BI variants were the focus of several investigations on drug pharmacokinetics and cancer susceptibility. However, no information has been available on association between SLCO1B1 and colorectal cancer risk. Therefore, the study aims to investigate the relationship between colorectal cancer and the functional common variants of SLCO1B1 (388 A>G, -11187 G>A, 521 T>C) and to estimate the prevalence of these variants in the Turkish population. To that end, the distributions of the variants were determined in 100 patients with colorectal cancer and 150 healthy volunteers. SLCO1B1 521 T>C was statistically significantly associated with colorectal cancer risk (odds ratio [OR]=2.66; 95% confidence interval [CI]=1.31-5.41; p=0.0057). In haplotype-based analysis, SLCO1B1 haplotype G(388)-T(11187)-T(521) might be associated with the development of colorectal cancer (OR=4.26; 95% CI=1.62-11.16; p=0.002). We believe that the findings may be beneficial to the development of efficacious preventive strategies and therapies for colorectal cancer.

Flavin-containing monooxygenase 3 gene polymorphisms in Turkish population

Flavin-containing monooxygenases (FMOs) represent the second most important human monooxygenase system, after cytochrome P450s (CYPs) and catalyze the oxygenation of many chemicals containing nitrogen-, sulphur-, phosphorous-, selenium- and other nucleophilic heteroatoms. FMO3 is the prominent FMO form in adult human liver. For FMO3, both interindividual variability within a single ethnic group and variability between ethnic groups have been reported. In our study, three prevalent functional FMO3 variants (E158K, V257M, and E308G) were genotyped in healthy Turkish people by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) methods. The frequencies of alleles and haplotypes were compared with those obtained from different populations. It was found that FMO3 158K, 257M and 308G alleles, demonstrate impaired metabolism toward many FMO3 substrates, were observed frequently in Turkish population similar to the other populations. Also, the frequencies of haplotypes were determined based on individual allelic frequencies and it was observed that the most common haplotypes were haplotip EVE and KVE (E158K/V257M/E308G), which together accounted for 80% of all haplotypes. The obtained data from the present study could be useful for further studies assessing sensitivity to therapeutic drugs, environmental toxicants and common disease.

Acute effects of methiocarb on oxidative damage and the protective effects of vitamin E and taurine in the liver and kidney of Wistar rats

Methiocarb (MC) is a widely used carbamate pesticide in agriculture and health programs. Although the main molecular mechanism of carbamate toxicity involves acetylcholinesterase inhibition, studies have also implicated the induction of oxidative stress. Therefore, the present study was aimed to evaluate the effect of acute MC exposure on lipid peroxidation, antioxidant defense systems, histological changes in Wistar rats and the protective effect of pretreatment with vitamin E and taurine. A total of 48 rats were randomly divided into six groups. Rats in group I were given corn oil, while those in group III were dosed with vitamin E (100 mg/kg body weight (b.w.)) and in group V were dosed with taurine (50 mg/kg b.w.). Rats in group II were administered with MC only (25 mg/kg b.w., 1/4 of median lethal dose (LD(50))), while those in groups IV and VI were pretreated with vitamin E (100 mg/kg b.w.) and taurine (50 mg/kg b.w.) for 20 days, respectively, and then exposed to MC (25 mg/kg b.w.). The rats administered with MC showed significant increase in the levels of malondialdehyde in the liver and kidney as an index of lipid peroxidation. Levels of glutathione and activities of superoxide dismutase, catalase and glutathione peroxidase were significantly increased, while activity of glutathione reductase remained unchanged in both the tissues after MC treatment. Mild degenerative histological changes were observed in liver tissue, while the changes in kidney tissue were more severe then liver after MC treatment. Pretreatment with vitamin E and taurine resulted in a significant decrease in the lipid peroxidation and alleviating effects on antioxidant defense systems in both the tissues, while protective effects on the histological changes were shown only in kidney when compared with liver. In conclusion, the study has demonstrated that the acute MC exposure in Wistar rats caused oxidative damage on liver and kidney, which were partly ameliorated by the pretreatment of vitamin E and taurine.

Acute pancreatitis is associated with Ser608Leu iNOS polymorphism

Acute pancreatitis is an initially localized inflammation of the pancreatic gland. The precise mechanisms by which aetiological factors induce acute pancreatitis are not yet known, but when initiated, common inflammatory pathways seem to be involved, with cytokines being their components of major importance. The inducible nitric oxide synthase gene (iNOS) encodes an enzyme involved in the pathway of reactive oxygen species and induced in response to infection, cytokines. iNOS is capable of generating large quantities of nitric oxide produced during inflammation. The objective of this study was to investigate the association between acute pancreatitis risk and iNOS polymorphisms. The studied single-nucleotide polymorphisms (SNPs) were Ser608Leu, resulting in an amino acid substitution, and 1173C/T and 954G/C, both in the gene promoter region that is linked to increased enzyme expression, leading to higher NO production. The genotypes for the three SNPs were determined in 93 patients with acute pancreatitis and 60 controls without pancreatitis or cancer that were matched for age and gender. Data analysis was done by conditional logistic regression. It was found that the Ser608Leu polymorphism was more frequent among cases with acute pancreatitis compared to controls (OR = 2.88; 95% CI: 1.49-5.57; P = 0.002), although no individually statistically significant associations for the other SNPs studied were detected. We suggest that iNOS Ser608Leu can be used as a marker to define the risk of acute pancreatitis.

Acrylamide-induced oxidative stress in human erythrocytes

Acrylamide (AA), a widely used industrial chemical, is shown to be neurotoxic, mutagenic and carcinogenic. This study was carried out to investigate the effects of different doses of AA on lipid peroxidation (LPO), haemolysis, methaemoglobin (MetHb) and antioxidant system in human erythrocytes in vitro. Erythrocyte solutions were incubated with 0.10, 0.25, 0.50 and 1.00 mM of AA at 37°C for 1 hour. At the end of the incubation, malondialdehyde (MDA), an end product of LPO, was determined by liquid chromatography (LC) while total glutathione, reduced glutathione (GSH) levels, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) enzymes and the rates of haemolysis and MetHb were determined by spectrophotometric methods. All of the studied concentrations of AA increased MetHb formation and SOD activity, and induced MDA formation and haemolysis due to the destruction of erythrocyte cell membrane. AA caused a decrease in the activities of GSH-Px, CAT and GSH levels. However, these effects of AA were seen only at higher concentrations than AA intake estimated for populations in many countries. We suggest that LPO process may not be involved in the toxic effects of AA in low concentrations, although the present results showed that the studied concentrations of AA exert deteriorating effects on antioxidant enzyme activities, LPO process and haemolysis.

The proteasome is an integral part of solar ultraviolet a radiation-induced gene expression

Solar ultraviolet (UV) A radiation is a well known trigger of signaling responses in human skin fibroblasts. One important consequence of this stress response is the increased expression of matrix metalloproteinase-1 (MMP-1), which causes extracellular protein degradation and thereby contributes to photoaging of human skin. In the present study we identify the proteasome as an integral part of the UVA-induced, intracellular signaling cascade in human dermal fibroblasts. UVA-induced singlet oxygen formation was accompanied by protein oxidation, the cross-linking of oxidized proteins, and an inhibition of the proteasomal system. This proteasomal inhibition subsequently led to an accumulation of c-Jun and phosphorylated c-Jun and activation of activator protein-1, i.e. transcription factors known to control MMP-1 expression. Increased transcription factor activation was also observed if the proteasome was inhibited by cross-linked proteins or lactacystin, indicating a general mechanism. Most importantly, inhibition of the proteasome was of functional relevance for UVA-induced MMP-1 expression, because overexpression of the proteasome or the protein repair enzyme methionine sulfoxide reductase prevented the UVA-induced induction of MMP-1. These studies show that an environmentally relevant stimulus can trigger a signaling pathway, which links intracellular and extracellular protein degradation. They also identify the proteasome as an integral part of the UVA stress response.

Effects of trichlorfon on malondialdehyde and antioxidant system in human erythrocytes

Organophosphorus insecticides may induce oxidative stress leading to generation of free radicals and alteration in antioxidant system. The aim of this study was to examine the potency of trichlorfon, an organophosphate insecticide, to induce oxidative stress response in human erythrocytes in vitro. For this purpose trichlorfon solutions in different concentrations and erythrocyte solutions were incubated at 37 degrees C for 60 min. At the end of the incubation time, malondialdehyde (MDA), an end product of lipid peroxidation, total glutathione, reduced glutathione (GSH) levels, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) enzymes were determined by spectrophotometric methods. Trichlorfon increased MDA formation depended on the concentration. On the other hand, decreases in the GSH-Px activity, GSH levels and increases in the total glutathione levels, SOD and CAT activities were seen in the studied concentrations. The present findings indicate that the in vitro toxicity of trichlorfon may be associated with oxidative stress.