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Background: The main method to treatment of schizophrenia is long-term antipsychotic therapy, which not only improves the long-term prognosis of the disease and facilitates its transition to remission, but unfortunately also has a wide range of side effects such as hyperprolactinemia (HP) [1,2]. The main goal of pharmacogenetics is the search for predictors of response to therapy, as well as determining the probability of developing side effects [3]. The target genes of the clinical effects of antipsychotic drugs are genes determining activity of neurotransmitter systems and genes of biotransformation of xenobiotics. The present study aimed to investigate the most significant socio-demographic, clinical and genetic indicators that significantly contribute to the development of HP. Methods: Four hundred and forty-six Russian patients with schizophrenia were examined. The average age of patients was 41.5 ± 13.4 years. Clinical symptomatology was assessed with Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impression (CGI) scale, the scale of side effect assessment (UKU). Evaluation of serum prolactin level was performed by ELISA using reagents set PRL of Test System (USA). Regression analysis was performed with HP as a dependent dichotomous variable and polymorphisms as factors. After calculation of the regression model was performed mixed discriminant analysis followed by cross-valuation for the selected predictors. For the final model sensitivity, specificity, AUC (Area Under Curve), positive and negative predictive values were calculated. Results: We studied 88 neurotransmitter polymorphic genes variants including HTR2C, HTR3A, HTR3B, HTR6, HTR2A, HTR1A, HTR1B, DRD1, DRD2, DRD2/ANKK1, DRD3, DRD4, SLC6A3, SLC6A2, COMT and genes of biotransformation of xenobiotics CYP1A2*1F, CYP2D6*3, CYP2D6*4, CYP2C19*3, CYP2C19*17, CYP2C19*2, GSTP1. In patients without HP, the average level of the hormone was 12.9 [8.12; 16.85] ng/ml, and in patients with HP: 49.66 [32.47; 76.39] ng/ml. In the analysis of the distribution of patients by sex, the prevalence of patients of female gender was revealed in the group with HP (63.8%), and in the group without HP male sex was most prevalent (70.0%). This indicates that the female gender is a factor determining vulnerability regarding the development of this side effect on the background of antipsychotic therapy (p = 0.006). Based on the results of a pharmacogenetic research a molecular-genetic panel for the development of neuroendocrine side effects of antipsychotic therapy in patients with schizophrenia was developed, which includes both genetic variants and as other signs: age, sex, daily average antipsychotics doses (expressed in chlorpromazine equivalents), ``rs1176744” (HTR3B), ``rs10042486” (HTR1A), ``rs936461” (DRD4), ``rs134655" (DRD2), ``rs179997” (ATXN1), ``rs1076562” (DRD2), ``rs3773678” (DRD3), ``rs167771” (DRD3), ``rs1587756” (DRD3), ``rs3892097” (CYP2D6*4), ``rs1341239” (PRL), ``rs4975646” (SLC6A3), ``rs13333066” (SLC6A2). Conclusion: This molecular-genetic panel can be used to predict the risk of developing HP even before the start of treatment of patients with schizophrenia for purposeful individual therapeutic treatment in this category of patients. Work has been done with support of the Russian Science Foundation (project no. 14-35-00023) Acknowledgement: Work has been done with support of the Russian Science Foundation (project no. 14-35-00023)

Predictive genetic model for levodopa-induced dyskinesia in patients with Parkinson's disease S.A. Ivanova(1), V.M. Alifirova(2), M.B. Freidin(3), I.V. Pozhidaev(4), O.Y. Fedorenko(4), N.A. Bokhan(4), I.A. Zhukova(5), N.G. Zhukova(5), B. Wilffert(6), A.J.M. Loonen(6) (1)Mental Health Research Institute, Molecular Genetics and Biochemistry Laboratory, Tomsk, Russia (2)Siberian State Medical University, Department of Neurology and Neurosurgery, Tomk, Russia (3)Tomsk National Research Medical Center of the Russian Academy of Sciences, Research Institute of Medical Genetics, Tomsk, Russia (4)Tomsk National Research Medical Center of the Russian Academy of Sciences, Mental Health Research Institute, Tomsk, Russia (5)Siberian State Medical University, Department of Neurology and Neurosurgery, Tomsk, Russia (6)University of Groningen, Groningen Research Institute of Pharmacy, Groningen, The Netherlands Parkinson's disease (PD), a common neurodegenerative disorder caused by the loss of the dopaminergic input to the basal ganglia, is commonly treated with levodopa (L-DOPA). The use of this drug, however, is severely limited by adverse effects. Levodopa-induced dyskinesia (LID) is one of these and characterized by involuntary muscle movements that occur as a consequence of chronic levodopa treatment. LID is a substantial barrier to effective symptomatic management of PD as up to 45% of L-DOPA users develop LID within 5 years [1]. Clinical heterogeneity of LID suggests a significant role of endogenous factors in determining their prevalence. Some evidences suggest a relationship between LID and specific genetic variants, such as polymorphisms in the genes controlling enzymes responsible for drug and monoamine metabolism, neurotransmitter receptors and proteins involved in oxidative stress or antioxidant function [2–4]. Objective: To investigate a contribution of polymorphic variants of neurotransmitter receptors and cytochrome genes in the development of LID in PD patients. Methods: A total of 212 PD patients who received L-DOPA therapy were studied. Dyskinesia was assessed by using the Abnormal Involuntary Movement Scale (AIMS). DNA extraction and genotyping were conducted according to standard protocols and blind to the clinical status of the subjects. Genotyping was carried out for 72 SNPs of DRD1, DRD2, DRD2/ANKK1, DRD3, DRD4, HTR2C, HTR3A, HTR3B, HTR6, HTR2A, HTR1A, HTR1B, CYP1A2*1F, CYP2D6*3, CYP2D6*4, CYP2C19*3, CYP2C19*17, CYP2C19*2, and GSTP1 genes using MassARRAY® Analyzer 4 (Agena Bioscience™) and the set SEQUENOM Consumables iPLEX Gold 384. Discriminant analysis and receiver operating curve (ROC)-analysis were carried out to build a genetic predictive model for dyskinesia. Results: Group of PD patients consists of 149 females and 83 males (age ranging from 40 to 86 years, average age 68.7 ± 7.6 years). The mean age of onset is 60.04 ± 9.46 years, average disease duration is 9.79 ± 5.57 years. Dyskinesia was reported in 57 (26.9%) patients. The best discriminant model was obtained with the following predictors: rs11721264, rs165774, rs3758653, rs4245147, rs6313, rs1364043, rs2734849, rs324035, rs6311, rs11246226 and rs4244285. These polymorphisms are localized in the following genes: DRD3 (rs11721264, rs324035), DRD4 (rs3758653, rs11246226), DRD2 (rs4245147, rs2734849), HTR2A (rs6313, rs6311), HTR1A (rs1364043). The discriminant model using this set of SNPs gives the error of classification about 13% and the AUC 0.795. Depending on the anticipated frequency of LID, positive and negative predictor values varied between 0.745–0.834 and 0.864–0.916, respectively. We hypothesized in our previous studies that the pathological basis of LID might be degeneration of indirect pathway medium spiny neurons [5]. These indirect pathway medium spiny neurons carry type 2 family dopamine receptors (DRD2, DRD3, DRD4), and HTR2A receptors. Moreover, dopamine release may be promoted by inhibiting serotonergic neurotransmission. Hence, the current findings are well in line with this hypothesis. Conclusion: The resulting panel of 11 SNPs provides a sufficiently high accuracy of LID prediction. The use of this panel in a prospective study will clarify the prospects for its application in clinical practice for predicting risk of LID in patients with PD. References [1] Rascol, O., Brooks, D.J., Korczyn, A.D., et al., 2000. Study Group: A five–year study of the incidence of dyskinesia in patients with early Parkinson's disease who were treated with ropinirole or L–DOPA. N Engl J Med 342, 1484–1491. [2] Ivanova, S.A., Fedorenko, O.Yu., Freidin, M.B., et al., 2016. Dissimilar mechanistic background of peripheral and orofacial hyperkinesia in patients with Parkinson's disease and levodopa-induced dyskinesia. Physiology and Pharmacology 19, 216–221. [3] Kaplan, N., Vituri, A., Korczyn, A.D., et al., 2014. Sequence variants in SLC6A3, DRD2, and BDNF genes and time to levodopa-induced dyskinesias in Parkinson's disease. J Mol Neurosci 53 (2), 183–188. [4] Loonen, A.J.M., Ivanova, S.A., 2016. Role of 5-HT2C receptors in dyskinesia. International Journal of Pharmacy and Pharmaceutical Sciences 8 (1), 5–10. [5] Loonen, A.J., Ivanova, S.A., 2013. New insights into the mechanism of drug-induced dyskinesia. CNS Spectr 18, 15–20. Keywords: Genetics / Molecular genetics Parkinson's disease levodopa-induced dyskinesia

Ankylosing spondylitis (AS) is a chronic inflammatory disease of unknown origin. The aim of this study is to clarify the relationships between susceptibility and severity of AS and GST-mu1 (GSTM1), GST-theta1 (GSTT1), GST-pi1 (GSTP1)-Ile105Val and angiotensin-converting enzyme (ACE) I/D polymorphisms in AS patients. One hundred thirty-eight AS patients and seventy-one healthy controls were enrolled in this study. Erythrocyte sedimentation rate and C-reactive protein (CRP) levels of the AS patients were recorded. The scores of the numeric rating scale (NRS) pain, the Bath Ankylosing Spondylitis Activity Index, the Bath Ankylosing Spondylitis Metrology Index and the Bath Ankylosing Spondylitis Functional Index were calculated. The genotypes distributions and allele frequencies of GSTM1, GSTT1, GSTP1-Ile105Val and ACE I/D polymorphisms were compared between patients and healthy controls. The Multiplex polymerase chain reaction (PCR) and the PCR-restriction fragment length polymorphism methods were used to detect the polymorphisms of ACE I/D, the GSTT1 and GSTM1 genes and the GSTP1-Ile105Val polymorphism, respectively. There were significantly higher levels of the GSTT1 null and the ACE II genotypes in AS patients compared to those in healthy controls (p = 0.002 and 0.005, respectively). We found significantly higher levels of CRP and the NRS pain scores in the patients with ACE ID or DD genotypes compared to those in the patients with ACE II genotypes (p = 0.005 and 0.035, respectively). The present results showed that genes involved in protection from oxidative stress and ACE gene may influence disease development and course in AS.

In this study, we aimed to investigate the extent of genotoxic risk and the association between null GSTM1/GSTT1 and GSTP1 Ile105Val variants and cellular DNA damage, as measured by micronucleus (MN) assay in a group of agricultural workers from Denizli, Turkey. Peripheral blood samples were collected from 116 subjects, including 58 workers who were occupationally exposed to pesticides and 58 healthy unexposed controls. The MN frequencies of each individual were assessed by cytokinesis-blocked micronuclei assays on lymphocytes. Genotypes for different GST variants were determined using polymerase chain reaction-based methods. A significant 3.4-fold increase in MN frequency was observed in workers compared with the controls ( p < 0.001). Among the GST genotypes, only the GSTM1 null genotype was found to be significantly associated with an increased MN frequency in workers ( p = 0.01). Individuals with a concomitant null GSTM1/GSTT1 genotype demonstrated a significant ( p = 0.01) increase in MN frequency compared with those with functional isozymes in the exposed worker group. The association of the GSTM1 null genotype with higher MN frequency suggests that it may be a modifier of genotoxic risk in individuals exposed to pesticides and may thus be a candidate susceptibility biomarker for human biomonitoring studies.

The Zeta class of glutathione transferases (GSTs) has only recently been discovered and hence has been poorly characterized. Here we investigate the substrate binding and kinetic mechanisms of the human Zeta class GSTZ1c-1c by means of pre-steady state and steady-state experiments and site-directed mutagenesis. Binding of GSH occurs at a very low rate compared with that observed for the more recently evolved GSTs (Alpha, Mu, and Pi classes). Moreover, the single step binding mechanism observed in this enzyme is reminiscent of that found for the Theta class enzyme, whereas the Alpha, Mu, and Pi classes have adopted a multistep binding mechanism. Replacement of Cys16 with Ala increases the rate of GSH release from the active site causing a 10-fold decrease of affinity toward GSH. Cys16 also plays a crucial role in co-substrate binding; the mutant enzyme is unable to bind the carcinogenic substrate dichloroacetic acid in the absence of GSH. However, both substrate binding and GSH activation are not rate-limiting in catalysis. A peculiarity of the hGSTZ1c-1c is the half-site activation of bound GSH. This suggests a primitive monomer-monomer interaction that, in the recently diverged GSTP1-1, gives rise to a sophisticated cooperative mechanism that preserves the catalytic efficiency of this GST under stress conditions.

Simsek, Erdal/0000-0002-2484-4676; Kilic, Murat/0000-0002-1377-2021; Bozer, Busra/0000-0002-7280-4417 WOS: 000350978900010 PubMed: 24647742 Background Aortic aneurysms are vascular diseases that are associated with high mortality and morbidity. Cytochrome P450 CYP1A1 and glutathione S-transferase (GSTP1) isozymes were searched and compared with the patients who had experienced aortic surgery due to aortic aneurysm and atherosclerotic patients without aneurysm to find the relation of the oxidative stress with the aneurysms. Materials and Methods Study group consisted of the patients with the diagnosis of aortic aneurysm (group I, n: 12) and control group who were operated for coronary bypass surgery: preoperatively drug users (group II, n: 21) and nonusers (group Ill, n: 15). Paraffin sections (4 pm thick) of aortic biopsy materials were stained with hematoxylin and eosine, CYP1A1 and GSTP1 immunohistochemical markers. The specimens were evaluated using light microscopy at 40- to 400-fold magnification. Results The expressions of CYP1A1 and GSTP1 isozymes were found statistically significantly higher in the patients who have an aortic aneurysm than both the control groups (p < 0.05). There was no significant association between protein expressions, drugs and duration of usage, patient's demographic variables, and smoking (p > 0.05). Conclusions In this pioneering study, CYP1A1 and GSTP1 isozymes are related with the aneurysms. The strategy that prevents the oxidative stress for the patients who had aortic aneurysms could be a valuable choice of searching to effect the aneurysmal progression.

Oxidative stress was related with carpal tunnel syndrome (CTS). We aimed to clarify the associations between glutathione S-transferase (GST)M1, GSTT1 and GSTP1-Ile105Val polymorphisms and CTS. One hundred-forty patients with CTS and 97 healthy controls were enrolled in this study. Tinel and Phalen signs were noted as positive or negative. Functional and clinical status of patients was evaluated by the Boston Questionnaire. The intensity of hand and/or wrist pain was evaluated on 10 cm visual analog scale (VAS). We applied the polymerase chain reaction (PCR) to determine the polymorphisms of the GSTM1 and GSTT1 and the PCR-restriction fragment length polymorphism method for detecting the GSTP1-Ile105Val polymorphism. The M1 null genotype was significantly higher in patients with CTS compared to healthy controls, and the M1 null genotype seemed to increase the risk of CTS approximately two-fold (P = 0.011; odds ratio (OR) = 1.98; 95 % confidence interval (CI) 1.17-3.36). The M1 null, T1 present combined genotype was significantly higher in patients with CTS compared to healthy controls (P = 0.043); however, it seemed not to increase the risk of CTS (P = 0.14; OR = 0.62; 95 % CI 0.33-1.76). We found significantly higher levels of the VAS, Boston Symptom Severity Scale and Phalen sign in patients with the Ile/Val or the Val/Val genotypes compared to those in patients with the Ile/Ile genotype (P = 0.003, 0.004 and 0.044, respectively). We proposed that genes involved in the protection from oxidative stress may influence the susceptibility, clinical and functional status of CTS. The GSTM1 null genotype may be related with the development of CTS, whereas the Val allele of GSTP1-Ile105Val polymorphism may be associated with worse functional and clinical status in CTS.

Objective: To investigate the polymorphism rates and possible roles of glutathione-s-transferase M1, T1, and P1 gene polymotphisms in the predisposition to endometrial cancer in Caucasian women. Materials and Methods: Serum samples and medical records were collected from 53 Caucasian women with newly diagnosed endometrial cancer and 67 women of the same race without any known history of cancer. Multiplex polymerase chain reaction (PCR) analysis was used to assess glutathione-s-transferase M1 (GSTM1) and T1 gene polymorphisms. Polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) method was used in salvage of GSTP1 gene polymorphism. Results: Frequencies of GSTM1 and GSTT1 null genotypes were not significantly different between the controls and patients with endometrial cancer (56.7% vs 52.8%, p = 0.671; 32.8% vs 26.4%, p = 0.574, respectively). The authors were not able to demonstrate any association between neither GSTP1 genotypes nor allele frequencies and endometrial carcinoma in the population studied (p = 0.310, p = 0.318, respectively). Moreover, no significant association could be demonstrated with GSTM1 and GSTT1 polymorphisms and clinical stages of endometrial cancer. Nevertheless, there was a significant difference between the frequencies of GSTP1 AA and GG genotypes in relation to Stage I disease when compared with advanced stages of endometrial carcinoma (p = 0.03). In addition, no association was found between polymorphisms of GST suspergene family and non-endometrioid type endometrial carcinomas. Conclusion: These results suggest that GSTT1, GSTM1, and GSTP1 polymorphisms are not associated with endometrial cancer in the Caucasian population.

The factors leading to the development of Chronic Myeloid Leukemia (CML) are not fully known. Associations between polymorphisms for genes encoding Glutathione S-transferase (GST) enzymes involved in Phase II detoxification reactions and susceptibility to some cancers have been shown in several studies. The aim of the present study was to investigate the influence of the GSTP1 (IIe105Val) gene polymorphism on human susceptibility to CML. Seventy-one CML patients and 67 control subjects with no cancer history were enrolled in our study . The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to identify the GSTP1 (lle105Val) gene polymorphism. Genotypes were determined according to the bands that formed in agarose gels via gel electrophoresis. Leukocytes in the CML patient group were significantly different from those in the control group (p=0.0001). The frequency of the GSTP1 Val allele was found to be 22% in CML patients and 31% in controls. However, no statistical variation was found to exist between controls and patients in terms of the GSTP1 Val allele frequency (p=0.199). The relationship between the GSTP1 (IIe105Val) gene polymorphism and CML is not fully understood. Our results provide no evidence of a relationship between the GSTP1 (IIe105V al) gene polymorphism and susceptibility to CML in Turkish patients. However, these findings should be confirmed in studies with larger sample sizes.

Humans are exposed to acrylamide in their diet and cigarette smoke. Acrylamide is metabolized into glycidamide by CYP2E1. However, very few studies regarding the effects of acrylamide on cytochrome P450 and Glutathione S-Transferase (GST) isozymes have been pursued. The aim of this study is to elucidate the effects of acrylamide on cytochrome P450 and GST isozymes in HepG2 cell line. Treatment with 1.25 and 2.5 mM acrylamide caused 9.5- and 3.7-fold increases and 4.0- and 3.3-fold increases in CYP1A-associated ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities, respectively. These increases were consistent with increases in mRNA and protein levels of these isozymes. Similarly, CYP2E1-associated aniline 4-hydroxylase (ANH) activity, protein levels, and mRNA levels increased 2.1- and 2.6-fold, 2.4- and 3.2-fold, and 1.4- and 1.9-fold following 1.25 and 2.5 mM acrylamide treatments, respectively. In addition, GST-mu activity was increased 2.4- and 5.1-fold by acrylamide. Moreover, GST-mu mRNA and protein levels increased twofold as a result of acrylamide treatment. In contrast, GST-pi protein and mRNA levels decreased significantly. In conclusion, human cell exposure to acrylamide causes an increase in the levels of carcinogenicity and toxicity and a disturbance in drug metabolism, possibly due to complex effects on P450 and GST isozymes. © Springer Science+Business Media B.V. 2012.

Objective: This work investigates the role of glutathione S-transferase M1 (GSTM1), glutathione S-transferase T1 (GSTT1), and glutathione S-transferase P1 (GSTP1) enzymes and polymorphisms, which are found in phase II detoxification reactions in the development of cervical cancer. Methods: This study was conducted with 46 patients diagnosed with cervical cancer and 52 people with no cancer history. Multiplex PCR methods were used to evaluate the GSTM1 and GSTT1 gene polymorphism. However, the GSTP1 (Ile105Val) gene polymorphism was studied using a PCR-RFLP method. The patient and control groups were compared using a chi-square test with p0.05). Conclusion: Our results demonstrate that GSTT1, GSTM1, and GSTP1 polymorphisms are not associated with cervical cancer in Turkish patients.

Anti-inflammatory properties of azithromycin (AZM) have been proposed as possible mechanisms of clinical beneficial effects in patients with cystic fibrosis (CF). Altered glutathione (GSH) transport in cystic fibrosis transmembrane regulator protein (CFTR)deficient cells leads to the occurrence of oxidative stress that finally induces glutathione S-transferase (GST) activity. The present investigation was aimed to verify the effects of AZM on GST activity and expression in CIF airway cells in vitro and in vivo. AZM exposure significantly decreased GSTT1 and GSTM1 mRNA and protein expression in IB3-1, restoring the levels to those observed in non-CF C38 cells, which also express lower levels of gamma-glutamyltransferase (GGT) activity than IB3-1. In another CF cell line, 2CFSMEo-, AZM produced 45% reduction in GSTT1 and GSTM1 mRNA levels. AZM reduced GST activity by approximately 25% and 40% in IB3-1 and 2CFSMEo- cells, respectively. GSTP1 was similarly expressed in all CIF and non-CIF cells and was unaffected by AZM. The anti-inflammatory cytokine IL-10 down-modulated GST activity at similar levels, supporting a link between GST inhibition and anti-inflammatory properties of AZM. In bronchoalveolar lavage fluid of CIF mice homozygous for the F508 del mutation, GSTM1 protein levels were undetectable after AZM treatment. The association between increased GST expression and activity, together with its reversal by AZM treatment in vitro and in vivo, suggest novel antioxidant properties for this drug. The issue whether decreased GST activity may directly concur to anti-inflammatory properties of AZM or is rather a marker of the oxidative status of CIF cells will require additional studies.

The possible nuclear compartmentalization of glutathione S-transferase (GST) isoenzymes has been the subject of contradictory reports. The discovery that the dinitrosyl-diglutathionyl- iron complex binds tightly to Alpha class GSTs in rat hepatocytes and that a significant part of the bound complex is also associated with the nuclear fraction (Pedersen, J. Z., De Maria, F., Turella, P., Federici, G., Mattei, M., Fabrini, R., Dawood, K. F., Massimi, M., Caccuri, A. M., and Ricci, G. (2007) J. Biol. Chem. 282, 6364–6371) prompted us to reconsider the nuclear localization of GSTs in these cells. Surprisingly, we found that a considerable amount of GSTs corresponding to 10% of the cytosolic pool is electrostatically associated with the outer nuclear membrane, and a similar quantity is compartmentalized inside the nucleus. Mainly Alpha class GSTs, in particular GSTA1-1, GSTA2-2, and GSTA3-3, are involved in this double modality of interaction. Confocal microscopy, immunofluorescence experiments, and molecular modeling have been used to detail the electrostatic association in hepatocytes and liposomes. A quantitative analysis of the membrane-bound Alpha GSTs suggests the existence of a multilayer assembly of these enzymes at the outer nuclear envelope that could represent an amazing novelty in cell physiology. The interception of potentially noxious compounds to prevent DNA damage could be the possible physiological role of the perinuclear and intranuclear localization of Alpha GSTs.

The new glutathione S-transferase inhibitor 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX) is cytotoxic toward P-glycoprotein-overexpressing tumor cell lines, i.e. CEM-VBL10, CEM-VBL100, and U-2 OS/DX580. The mechanism of cell death triggered by NBDHEX has been deeply investigated in leukemia cell lines. Kinetic data indicate a similar NBDHEX membrane permeability between multidrug resistance cells and their sensitive counterpart revealing that NBDHEX is not a substrate of the P-glycoprotein export pump. Unexpectedly, this molecule promotes a caspase-dependent apoptosis that is unusual in the P-glycoprotein-overexpressing cells. The primary event of the apoptotic pathway is the dissociation of glutathione S-transferase P1-1 from the complex with c-Jun N-terminal kinase. Interestingly, leukemia MDR1-expressing cells show lower LC50 values and a higher degree of apoptosis and caspase-3 activity than their drug-sensitive counterparts. The increased susceptibility of the multidrug resistance cells toward the NBDHEX action may be related to a lower content of glutathione S-transferase P1-1. Given the low toxicity of NBDHEX in vivo, this compound may represent an attractive basis for the selective treatment of MDR1 P-glycoprotein-positive tumors.

The cyclopentenone prostaglandin A2 (PGA2) is known to inhibit cell proliferation, and metabolism of this compound thus might be important in controlling its ultimate function. The glutathione-related metabolism of PGA2 was therefore investigated both with purified glutathione S-transferase P1-1 (GSTP1-1) and with IGR-39 human melanoma cells. Firstly, the irreversible inhibition of human GSTP1-1 and its mutants C47S, C101S, and C47S/C101S was studied. PGA2 appeared to inhibit GSTP1-1 mainly by binding to the cysteine 47 moiety of the enzyme. This binding was reversed by a molar excess of GSH, indicating that retro-Michael cleavage occurs. Secondly, after exposing IGR-39 human melanoma cells to PGA2, both diastereoisomers of the PGA2-glutathione conjugate are excreted into the medium, although with a clear excess of the S-form, due to its preferential formation by the GSTP1-1 present in the cells. Thirdly, the effect of PGA2 on intracellular GST activity was determined by quantification of the excreted glutathione conjugate S-(2,4-dinitrophenyl)glutathione (DNPSG) after exposure to 1-chloro-2,4-dinitrobenzene. DNPSG excretion was inhibited after incubation with 10 or 20 μM PGA2 for 1 or 4 hr, as a result of glutathione depletion, reversible GST inhibition, and covalent modification of intracellular GST. Furthermore, PGA2 also inhibited transport of DNPSG by the multidrug resistance-associated protein, an effect that was reversible and competitive. In conclusion, PGA2 modulates all three aspects of the glutathione-mediated biotransformation system, i.e. GSH levels, GSTP1-1 activity, and transport of GSH conjugates. A role for GSTP1-1 as a specific transport protein inside the cell is indicated. Copyright (C) 1999 Elsevier Science Inc.

The cyclopentenone prostaglandin A2 (PGA2) is known to inhibit cell proliferation, and metabolism of this compound thus might be important in controlling its ultimate function. The glutathione-related metabolism of PGA2 was therefore investigated both with purified glutathione S-transferase P1-1 (GSTP1-1) and with IGR-39 human melanoma cells. Firstly, the irreversible inhibition of human GSTP1-1 and its mutants C47S, C101S, and C47S/C101S was studied. PGA2 appeared to inhibit GSTP1-1 mainly by binding to the cysteine 47 moiety of the enzyme. This binding was reversed by a molar excess of GSH, indicating that retro-Michael cleavage occurs. Secondly, after exposing IGR-39 human melanoma cells to PGA2, both diastereoisomers of the PGA2-glutathione conjugate are excreted into the medium, although with a clear excess of the S-form, due to its preferential formation by the GSTP1-1 present in the cells. Thirdly, the effect of PGA2 on intracellular GST activity was determined by quantification of the excreted glutathione conjugate S-(2,4-dinitrophenyl)glutathione (DNPSG) after exposure to 1-chloro-2,4-dinitrobenzene. DNPSG excretion was inhibited after incubation with 10 or 20 μM PGA2 for 1 or 4 hr, as a result of glutathione depletion, reversible GST inhibition, and covalent modification of intracellular GST. Furthermore, PGA2 also inhibited transport of DNPSG by the multidrug resistance-associated protein, an effect that was reversible and competitive. In conclusion, PGA2 modulates all three aspects of the glutathione-mediated biotransformation system, i.e. GSH levels, GSTP1-1 activity, and transport of GSH conjugates. A role for GSTP1-1 as a specific transport protein inside the cell is indicated. Copyright (C) 1999 Elsevier Science Inc.