RP-HPLC method for quantitative determination of cystathionine, cysteine and glutathione: An application for the study of the metabolism of cysteine in human brain

Light-Controlled Anticancer Activity and Cellular Uptake of a Photoswitchable Cisplatin Analogue

A photoactive analogue of cisplatin was synthesized with two arylazopyrazole ligands, able to undergo trans-cis/cis-trans photoisomerizations. The cis photoisomer showed a dark half-life of 9 days. The cytotoxicities of both photoisomers of the complex were determined in several cancer and normal cell lines and compared to that of cisplatin. The trans photoisomer of the complex was much more cytotoxic than both the cis photoisomer and cisplatin, and was more toxic for cancer (4T1) than for normal (NMuMG) murine breast cells. 4T1 cell death occurred through necrosis. Photoisomerization of the trans and cis photoisomers internalized by the 4T1 cells increased and decreased their viability, respectively. The cellular uptake of the trans photoisomer was stronger than that of both the cis photoisomer and cisplatin. Both photoisomers interacted with DNA faster than cisplatin. The trans photoisomer was bound stronger by bovine serum albumin and induced a greater decrease in cellular glutathione levels than the cis photoisomer.

Differences in nonoxidative sulfur metabolism between normal human breast MCF-12A and adenocarcinoma MCF-7 cell lines

Recent studies have revealed the role of endogenous hydrogen sulfide (H2S) in the development of breast cancer. The capacity of cells to generate H2S and the activity and expression of the main enzymes (cystathionine beta synthase; CBS, cystathionase γ-lyase; CGL, 3-mercaptopyruvate sulfurtransferase; MPST and thiosulfate sulfurtransferase; TST) involved in H2S metabolism were analyzed using an in vitro model of a non-tumourigenic breast cell line (MCF-12A) and a human breast adenocarcinoma cell line (MCF-7). In both cell lines, MPST, CGL, and TST expression was confirmed at the mRNA (RT-PCR) and the protein (Western Blot) level, while CBS expression was detected only in MCF-7 cells. Elevated levels of GSH, sulfane sulfur and increased CBS and TST activity were presented in the MCF-7 compared to the MCF-12A cells. It appears that cysteine might be mainly a substrate for GSH synthesis in breast adenocarcinoma. Increased capacity of the cells to generate H2S was shown for MCF-12A compared to MCF-7 cell line. Results suggest an important function of CBS in H2S metabolism in breast adenocarcinoma. The presented work may contribute to further research on new therapeutic possibilities for breast cancer - one of the most frequently diagnosed types of cancer among women.

Heart and kidney H2S production is reduced in hypertensive and older rats

The prevalence of hypertension increases with age, but the mechanisms linking this phenomenon are not well understood. Hydrogen sulfide (H₂S) may be involved in this process, as it plays a role in the cardiovascular system, affecting blood pressure and heart and kidney functions. The aim of this study was to evaluate the influence of hypertension and aging on sulfur-containing compounds metabolism in the hearts and kidneys of Wistar Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR) of different age groups. We determined the expression and activity of four enzymes participating in H₂S production: cystathionine beta-synthase (CBS), cystathionine gamma-lyase (CTH), 3-mercaptopyruvate sulfurtransferase (MPST), and thiosulfate sulfurtransferase (TST). The levels of reduced/oxidized glutathione, cysteine, cystine, and cystathionine, and the ability of tissues to form hydrogen sulfide were also investigated. Tissues obtained from younger WKY rats produced the highest amounts of H₂S. The effect of hypertension on the metabolism of sulfur-containing compounds was manifested by a decrease in sulfane sulfur concentrations in heart homogenates and a decrease in CTH activity in the kidneys. The hearts and kidneys of older WKY rats were characterized by lower MPST or CTH gene expression, respectively, compared to younger animals. Our study demonstrates that hypertension and aging influence cardiac and renal sulfur-containing compounds metabolism and reduce H₂S production. Furthermore, we showed that MPST plays a major role in the production of hydrogen sulfide in the heart and CTH in the kidneys of rats.

The Cytotoxicity of OptiBond Solo Plus and Its Effect on Sulfur Enzymes Expression in Human Fibroblast Cell Line Hs27

The aim of the study was to determine the cytotoxic concentrations and incubation times of the commonly used dental adhesive system OptiBond Solo Plus in its non-polymerized form, and to test how it relates to oxidative stress by determining the reduced and oxidized glutathione (GSH and GSSG) levels as well as to study its influence on cell number and the expression of selected sulfur enzymes, with particular emphasis on cystathionine γ-lyase (CTH) and 3-mercaptopyruvate (MPST), sulfurtransferase. All investigations were conducted on an in vitro model of human fibroblast cell line Hs27. Changes in cellular plasma membrane integrity were measured by the LDH test. The expression levels were determined by RT-PCR and Western blot protocols. Changes in cell number were visualized using crystal violet staining. The RP-HPLC method was used to determine the GSH and GSSG levels. Reduced cell number was shown for all tested concentrations and times. Changes in the expression on the mRNA and protein level were demonstrated for CTH and MPST enzymes upon exposure to the tested range of OptiBond concentrations. Levels of low-molecular sulfur compounds of reduced and oxidized glutathione were also established. Cytotoxic effect of OptiBond Solo Plus may be connected with the changes of MPST and CTH sulfur enzymes in the human fibroblast Hs27 cell line. The elevated levels of these enzymes could possibly show the antioxidant response to this dental adhesive system. OptiBond Solo Plus in vitro results should be taken into consideration for further in vivo tests.

The Expression and Activity of Rhodanese, 3-Mercaptopyruvate Sulfurtransferase, Cystathionine γ-Lyase in the Most Frequently Chosen Cellular Research Models

This paper provides information concerning the activity and expression levels of three sulfurtransferases (STRs): rhodanese (TST, EC: 2.8.1.1), 3-mercaptopyruvate sulfurtransferase (MPST, EC: 2.8.1.2) and cystathionine γ-lyase (CTH, EC: 4.4.1.1) in various cell lines. Since very limited data are available in the scientific literature on this subject, the available data are included in this paper. These shortages often force the researchers to carry out their own screening tests that allow them to choose an appropriate model for their further studies. This work supplements the existing deficiencies in this area and presents the activity and expression of STRs in the eight most frequently chosen cell lines: the mouse mammary gland cell line (NMuNG, ATCC: CRL-1636), mouse mammary gland tumor (4T1, ATCC: CRL-2539), mouse fibroblast (MEF, ATCC: SCRC-1008), mouse melanoma (B16-F1, ATCC: CRL-6323), human colorectal adenocarcinoma (Caco-2, ATCC: HTB-37), human embryonic kidney (HEK-293, ATCC: CRL-1573), human osteosarcoma (MG-63, ATCC: CRL-1427) and rat myocardium (H9c2, ATCC: CRL-1446). Changes in STRs activity are directly related to the bioavailability of cysteine and the sulfane sulfur level, and thus the present authors also measured these parameters, as well as the level of glutathione (its reduced (GSH) and oxidized (GSSG) form) and the [GSH]/[GSSG] ratio that determines the antioxidant capacity of the cells. STRs demonstrate diverse functionality and clinical relevance; therefore, we also performed an analysis of genetic variation of STRs genes that revealed a large number of polymorphisms. Although STRs still provide challenges in several fields, responding to them could not only improve the understanding of various diseases, but may also provide a way to treat them.

Hyaluronic Acid-Based Nanocapsules as Efficient Delivery Systems of Garlic Oil Active Components with Anticancer Activity

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in the oil-core nanocapsules based on a derivative of hyaluronic acid was investigated here as a way of protecting against oxidation and undesired interactions with blood and digestive track components. The nuclear magnetic resonance (¹H NMR) technique was used to follow the oxidation processes. It was proved that the shell of the capsule acts as a barrier limiting the sulfur oxidation, enhancing the stability of C=C bonds in DADS and DATS. Moreover, it was shown that the encapsulation inhibited the lysis of the red blood cell membrane (mainly for DADS) and interactions with serum or digestive track components. Importantly, the biological functions and anticancer activity of DADS and DATS were preserved after encapsulation. Additionally, the nanocapsule formulations affected the migration of neoplastic cells—a desirable preliminary observation concerning the inhibition of migration. The proposed route of administration of these garlic extract components would enable reaching their higher concentrations in blood, longer circulation in a bloodstream, and thus, imply a better therapeutic effect.

Hypertension and Aging Affect Liver Sulfur Metabolism in Rats

Hypertension and age are key risk factors for cardiovascular morbidity and mortality. Hydrogen sulfide (H2S), a gaseous transmitter, contributes significantly to regulating arterial blood pressure and aging processes. This study evaluated the effects of hypertension and aging on the hepatic metabolism of sulfur-containing compounds, the activity of the enzymes involved in sulfur homeostasis, and the liver's ability to generate H2S. Livers isolated from 16- and 60-week-old normotensive Wistar Kyoto rats (WKY) and Spontaneously Hypertensive Rats (SHR) were used to evaluate gene expression using RT-PCR, and the activity of enzymes participating in H2S metabolism, including thiosulfate sulfurtransferase (rhodanese; TST), cystathionine gamma-lyase (CTH), and 3-mercaptopyruvate sulfurtransferase (MPST). The levels of cysteine, cystine, reduced and oxidized glutathione were measured using RP-HPLC. SHR livers from both age groups showed a higher capacity to generate H2S than livers from WKY. The gene expression and activity of enzymes involved in sulfur metabolism differed between WKY and SHR, and between the age groups. For example, 16-week-old SHR had significantly higher activity of TST than 16-week-old WKY. Furthermore, differences between younger and older WKY rats in the expression and/or activity of TST and MPST were present. In conclusion, our study shows that arterial hypertension and aging affect hepatic sulfur metabolism and H2S production in rats. These findings pave the way for interventional studies evaluating a potential causal relation between liver sulfur metabolism, hypertension and aging.

Murine cellular model of mucopolysaccharidosis, type IIIB (MPS IIIB) - A preliminary study with particular emphasis on the non-oxidative l-cysteine metabolism

The lack of the N-alpha-glucosaminidase (Naglu) is responsible for the incidence of a rare disease - mucopolysaccharidosis, type IIIB (MPS IIIB). To date, studies have been conducted based on cells derived from patients suffering from MPS or using in vivo MPS mouse models. These limitations have allowed for defining our research goal - to create and characterize the first in vitro murine cellular MPS IIIB model. In the current work we present a new, stable cell line with confirmed accumulation of glycosaminoglycans. The line stability was achieved by immortalization using a lentivirus carrying the T-antigens of SV40. The Naglu^-/- cells were confirmed to produce no Naglu enzyme. To confirm the proper functioning of the in vitro MPS IIIB model, we determined the activity and expression of cystathionine γ-lyase, rhodanese and 3-mercaptopyruvate sulfurtransferase, as well as the level of low molecular-weight thiols (reduced and oxidized glutathione, cysteine and cystine). The results were referred to our earlier findings originating from the studies on the tissues of the Naglu^-/- mice that were used to create the lines. The results obtained in the Naglu^-/- cells were in accordance with the results found in the mouse model of MPS IIIB. It suggests that the presented murine Naglu^-/- cell lines might be a convenient in vitro model of MPS IIIB.

High performance liquid chromatography-electrospray ionization mass spectrometric (LC-ESI-MS) methodology for analysis of amino acid energy substrates in microwave-fixed microdissected brain tissue

Hypoglycemia deprives the brain of its primary energy source glucose. Reductions in whole-brain amino acid energy substrate levels suggest that these non-glucose fuels may be metabolized during glucose shortage. Recurring hypoglycemia can cause mal-adaptive impairment of glucose counter-regulation; yet, it is unclear if amplified reliance upon alternative metabolic substrates impedes detection of continuing neuro-glucopenia. This research aimed to develop high-sensitivity UHPLC-electrospray ionization mass spectrometric (LC-ESI-MS) methodology, for complementary use with high-neuroanatomical resolution microdissection tools, for measurement of glucogenic amino acid, e.g. glutamine (Gln), glutamate (Glu), and aspartate (Asp) content in the characterized glucose-sensing ventromedial hypothalamic nucleus (VMN) during acute versus chronic hypoglycemia. Results show that VMN tissue Gln, Glu, and Asp levels were significantly decreased during a single hypoglycemic episode, and that Gln and Asp measures were correspondingly normalized or further diminished during renewed hypoglycemia. Results provide proof-of-principle that LC-ESI-MS has requisite sensitivity for amino acid energy substrate quantification in distinctive brain gluco-regulatory structures under conditions of eu- versus hypoglycemia. This novel combinatory methodology will support ongoing efforts to determine how amino acid energy yield may impact VMN metabolic sensory function during persistent hypoglycemia.

In vivo 1 H MRS detection of cystathionine in human brain tumors

PURPOSE

To report the technical aspects of noninvasive detection of cystathionine in human brain glioma with edited MRS, and to investigate possible further acquisition improvements for robust quantification of this metabolite.

METHODS

In vivo ¹ H MR spectra were acquired at 3 T in 15 participants with an isocitrate dehydrogenase-mutated glioma using a MEGA-PRESS (MEscher GArwood point resolved spectroscopy) sequence previously employed for 2-hydroxyglutarate detection (T_R = 2 s, T_E = 68 ms). The editing pulse was applied at 1.9 ppm for the edit-on condition and at 7.5 ppm for the edit-off condition. To evaluate the editing efficiency, spectra were acquired in 1 participant by placing the editing pulse for the edit-on condition at 1.9, 2.03, and 2.16 ppm. Cystathionine concentration was quantified using LCModel and a simulated basis set. To confirm chemical shifts and J-coupling values of cystathionine, the ¹ H NMR cystathionine spectrum was measured using a high-resolution 500 MHz spectrometer.

RESULTS

In 12 gliomas, cystathionine was observed in the in vivo edited MR spectra at 2.72 and 3.85 ppm and quantified. The signal intensity of the cystathionine resonance at 2.72 ppm increased 1.7 and 2.13 times when the editing pulse was moved to 2.03 and 2.16 ppm, respectively. Cystathionine was not detectable in normal brain tissue.

CONCLUSION

Cystathionine can be detected in vivo by edited MRS using the same protocol as for 2-hydroxyglutarate detection. This finding may enable a more accurate, noninvasive investigation of cellular metabolism in glioma.

A possible mechanism of inhibition of U87MG and SH-SY5Y cancer cell proliferation by diallyl trisulfide and other aspects of its activity

The study was conducted to elucidate the mechanism of antiproliferative and antioxidative action of diallyl trisulfide (DATS), a garlic-derived organosulfur compound. Changes in the l-cysteine desulfuration, and the levels of cystathionine and non-protein thiols in DATS-treated human glioblastoma (U87MG) and neuroblastoma (SH-SY5Y) cells were investigated. The inhibition of proliferation of the investigated cells by DATS was correlated with an increase in the inactivated form of Bcl-2. In U87MG cells, an increased level of sulfane sulfur and an increased activity of 3-mercaptopyruvate sulfurtransferase (MPST) and rhodanese, the enzymes involved in sulfane sulfur generation and transfer, suggest that DATS can function as a donor of sulfane sulfur atom, transferred by sulfurtransferases, to sulfhydryl groups of cysteine residues of Bcl-2 and in this way lower the level of active form of Bcl-2 by S-sulfuration. Diallyl trisulfide antioxidative effects result from an increased level of cystathionine, a precursor of cysteine, and an increased glutathione level. MPST and rhodanese, the level of which is increased in the presence of DATS, can serve as antioxidant proteins.

Hydrogen Sulphide Production in Healthy and Ulcerated Gastric Mucosa of Rats

Hydrogen sulphide (H₂S) is produced endogenously via two enzymes dependent on pyridoxal phosphate (PLP): cystathionine beta-synthase (CBS, EC 4.2.1.22), cystathionase γ-liase (CTH, EC 4.4.1.1), and a third, 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2). H₂S strengthens the defence mechanisms of the gastric mucosal barrier, and plays an important role in gastroprotection, including the increased resistance to damage caused by various irritants and non-steroidal anti-inflammatory drugs. The study was conducted to determine the role of H₂S in ulcerated gastric mucosa of rats caused by immobilization in cold water (WRS). The activity and expression of γ-cystathionase, cystathionine β-synthase, 3-mercaptopyruvate sulfurtransferase, and rhodanese was compared with healthy mucosa, together with H₂S generation, and cysteine, glutathione, and cystathionine levels. The results showed that the defence mechanism against stress is associated with stimulation of the production of H₂S in the tissue and confirmed the observed advantageous effect of H₂S on healing of gastric ulcers. In case of animals pretreated with exogenous sources of H₂S and NaHS, and some changes observed in the ulcerated gastric mucosa tend to return to values found in the healthy tissue, a finding that is in accordance with the previously determined gastroprotective properties of H₂S. The results presented in this paper point to the possible role of rhodanese in H₂S production in the gastric mucosa of rats, together with the earlier mentioned three enzymes, which are all active in this tissue.

Is development of high-grade gliomas sulfur-dependent?

We characterized γ-cystathionase, rhodanese and 3-mercaptopyruvate sulfurtransferase activities in various regions of human brain (the cortex, thalamus, hypothalamus, hippocampus, cerebellum and subcortical nuclei) and human gliomas with II to IV grade of malignancy (according to the WHO classification). The human brain regions, as compared to human liver, showed low γ-cystathionase activity. The activity of rhodanese was also much lower and it did not vary significantly between the investigated brain regions. The activity of 3-mercaptopyruvate sulfurtransferase was the highest in the thalamus, hypothalamus and subcortical nuclei and essentially the same level of sulfane sulfur was found in all the investigated brain regions. The investigations demonstrated that the level of sulfane sulfur in gliomas with the highest grades was high in comparison to various human brain regions, and was correlated with a decreased activity of γ-cystathionase, 3-mercaptopyruvate sulfurtransferase and rhodanese. This can suggest sulfane sulfur accumulation and points to its importance for malignant cell proliferation and tumor growth. In gliomas with the highest grades of malignancy, despite decreased levels of total free cysteine and total free glutathione, a high ratio of GSH/GSSG was maintained, which is important for the process of malignant cells proliferation. A high level of sulfane sulfur and high GSH/GSSG ratio could result in the elevated hydrogen sulfide levels. Because of the disappearance of γ-cystathionase activity in high-grade gliomas, it seems to be possible that 3-mercaptopyruvate sulfurtransferase could participate in hydrogen sulfide production. The results confirm sulfur dependence of malignant brain tumors.

An application of RP-HPLC for determination of the activity of cystathionine β-synthase and γ-cystathionase in tissue homogenates

The RP-HPLC-based method of determination of the activity of cystathionine β-synthase and γ-cystathionase was undertaken in mouse liver, kidney and brain. Products of the reactions, such as cystathionine, α-ketobutyrate, cysteine and glutathione, were measured using the RP-HPLC method. A difference in the cystathionine level between homogenates with totally CTH-inhibiting concentrations of DL-propargylglycine and without the inhibitor was employed to evaluate the activity of cystathionine β-synthase. Gamma-cystathionase activity was measured using DL-homoserine as a substrate and a sensitive HPLC-based assay to measure α-ketobutyrate. The results confirmed high cystathionine β-synthase activity and no γ-cystathionase activity in brain, and high γ-cystathionase activity in mouse liver. The method presented here allows for evaluating the relative contribution of CBS and CTH to generation of H2S in tissues. Additionally, it provides results, which reflect the redox status (GSH/GSSG) of a tissue.

Simultaneous determination of glutathione, cysteine, homocysteine, and cysteinylglycine in biological fluids by ion-pairing high-performance liquid chromatography coupled with precolumn derivatization

Biologically active low-molecular-mass thiols, mainly including glutathione (GSH), cysteine (Cys), homocysteine (Hcy), and cysteinylglycine (Cys-Gly), are important physiological components in biological fluids, and their analytical methods have gained continuous attention over recent years. We developed and validated a novel HPLC method for the quantification of GSH, Cys, Hcy, and Cys-Gly in human plasma, urine, and saliva using 4-chloro-3,5-dinitrobenzotrifluoride as the derivatization reagent. Analyses were linear from 0.15 to 500 μM with the coefficient regression range of 0.9987-0.9994. Detection limits ranged from 0.04 to 0.08 μM (S/N=3). The developed method was applied to quantification of four thiols in human biological fluids collected from five donors with the concentration range of 2.50-124.25 μM, 0-72.81 μM, and 0-4.25 μM for plasma, urine, and saliva, respectively. The present method seemed to be an attractive choice for the determination of thiols in plasma, urine, and saliva.

Low-molecular-mass metal complexes in the mouse brain

The presence of labile low-molecular-mass (LMM, defined as <10 kDa) metal complexes in cells and super-cellular structures such as the brain has been inferred from chelation studies, but direct evidence is lacking. To evaluate the presence of LMM metal complexes in the brain, supernatant fractions of fresh mouse brain homogenates were passed through a 10 kDa cutoff membrane and subjected to size-exclusion liquid chromatography under anaerobic refrigerated conditions. Fractions were monitored for Mn, Fe, Co, Cu, Zn, Mo, S and P using an on-line ICP-MS. At least 30 different LMM metal complexes were detected along with numerous P- and S- containing species. Reproducibility was assessed by performing the experiment 13 times, using different buffers, and by examining whether complexes changed with time. Eleven Co, 2 Cu, 5 Mn, 4 Mo, 3 Fe and 2 Zn complexes with molecular masses <4 kDa were detected. One LMM Mo complex comigrated with the molybdopterin cofactor. Most Cu and Zn complexes appeared to be protein-bound with masses ranging from 4-20 kDa. Co was the only metal for which the "free" or aqueous complex was reproducibly observed. Aqueous Co may be sufficiently stable in this environment due to its relatively slow water-exchange kinetics. Attempts were made to assign some of these complexes, but further efforts will be required to identify them unambiguously and to determine their functions. This is among the first studies to detect low-molecular-mass transition metal complexes in the mouse brain using LC-ICP-MS.

Regional variations of antioxidant capacity and oxidative stress responses in HIV-1 transgenic rats with and without methamphetamine administration

HIV infection and methamphetamine (Meth) abuse both may lead to oxidative stress. This study used HIV-1 transgenic (HIV-1Tg) rats to investigate the independent and combined effects of HIV viral protein expression and low dose repeated Meth exposure on the glutathione (GSH)-centered antioxidant system and oxidative stress in the brain. Total GSH content, gene expression and/or enzymatic activities of glutamylcysteine synthetase (GCS), gamma-glutamyltransferase (GGT), glutathione reductase (GR), glutathione peroxidase (GPx), glutaredoxin (Glrx), and glutathione-s-transferase (GST) were measured. The protein expression of cystine transporter (xCT) and oxidative stress marker 4-hydroxynonenal (HNE) were also analyzed. Brain regions studied include thalamus, frontal and remainder cortex, striatum, cerebellum and hippocampus. HIV-1Tg rats and Meth exposure showed highly regional specific responses. In the F344 rats, the thalamus had the highest baseline GSH concentration and potentially higher GSH recycle rate. HIV-1Tg rats showed strong transcriptional responses to GSH depletion in the thalamus. Both HIV-1Tg and Meth resulted in decreased GR activity in thalamus, and decreased Glrx activity in frontal cortex. However, the increased GR and Glrx activities synergized with increased GSH concentration, which might have partially prevented Meth-induced oxidative stress in striatum. Interactive effects between Meth and HIV-1Tg were observed in thalamus on the activities of GCS and GGT, and in thalamus and frontal cortex on Glrx activity and xCT protein expression. Findings suggest that HIV viral protein and low dose repeated Meth exposure have separate and combined effects on the brain's antioxidant capacity and the oxidative stress response that are regional specific.