Inhibition of sphingolipid metabolism enhances resveratrol chemotherapy in human gastric cancer cells

Resveratrol, a chemopreventive agent, is rapidly metabolized in the intestine and liver via glucuronidation. Thus, the pharmacokinetics of resveratrol limits its efficacy. To improve efficacy, the activity of resveratrol was investigated in the context of sphingolipid metabolism in human gastric cancer cells. Diverse sphingolipid metabolites, including dihydroceramides (DHCer), were tested for their ability to induce resveratrol cytotoxicity. Exposure to resveratrol (100 μM) for 24 hr induced cell death and cell cycle arrest in gastric cancer cells. Exposure to the combination of resveratrol and dimethylsphingosine (DMS) increased cytotoxicity, demonstrating that sphingolipid metabolites intensify resveratrol activity. Specifically, DHCer accumulated in a resveratrol concentration-dependent manner in SNU-1 and HT-29 cells, but not in SNU-668 cells. LC-MS/MS analysis showed that specific DHCer species containing C24:0, C16:0, C24:1, and C22:0 fatty acids chain were increased by up to 30-fold by resveratrol, indicating that resveratrol may partially inhibit DHCer desaturase. Indeed, resveratrol mildly inhibited DHCer desaturase activity compared to the specific inhibitor GT-11 or to retinamide (4-HPR); however, in SNU-1 cells resveratrol alone exhibited a typical cell cycle arrest pattern, which GT-11 did not alter, indicating that inhibition of DHCer desaturase is not essential to the cytotoxicity induced by the combination of resveratrol and sphingolipid metabolites. Resveratrol-induced p53 expression strongly correlated with the enhancement of cytotoxicity observed upon combination of resveratrol with DMS or 4-HPR. Taken together, these results show that DHCer accumulation is a novel lipid biomarker of resveratrol-induced cytotoxicity in human gastric cancer cells.

Current status of neurointerventional activities in Korea

Neurointervention which deals with neurovascular disease in brain, head-and-neck and spines are one of the rapidly evolving medical fields. Several indices representing neurointerventional activities are still increasing year-by-year in Korea. We review current trend in major neurovascular diseases requiring usage of specific medical devices and some issues related to administrative process of the government approval.

Neutral sphingomyelinase 2 modulates cytotoxic effects of protopanaxadiol on different human cancer cells

Background

Some of ginsenosides, root extracts from Panax ginseng, exert cytotoxicity against cancer cells through disruption of membrane subdomains called lipid rafts. Protopanaxadiol (PPD) exhibits the highest cytotoxic effect among 8 ginsenosides which we evaluated for anti-cancer activity. We investigated if PPD disrupts lipid rafts in its cytotoxic effects and also the possible mechanisms.

Methods

Eight ginsenosides were evaluated using different cancer cells and cell viability assays. The potent ginsenoside, PPD was investigated for its roles in lipid raft disruption and downstream pathways to apoptosis of cancer cells. Anti-cancer effects of PPD was also investigated in vivo using mouse xenograft model.

Results

PPD consistently exerts its potent cytotoxicity in 2 cell survival assays using 5 different cancer cell lines. PPD disrupts lipid rafts in different ways from methyl-β-cyclodextrin (MβCD) depleting cholesterol out of the subdomains, since lipid raft proteins were differentially modulated by the saponin. During disruption of lipid rafts, PPD activated neutral sphingomyelinase 2 (nSMase 2) hydrolyzing membrane sphingomyelins into pro-apoptotic intracellular ceramides. Furthermore, PPD demonstrated its anti-cancer activities against K562 tumor cells in mouse xenograft model, confirming its potential as an adjunct or chemotherapeutic agent by itself in vivo.

Conclusions

This study demonstrates that neutral sphingomyelinase 2 is responsible for the cytotoxicity of PPD through production of apoptotic ceramides from membrane sphingomyelins. Thus neutral sphingomyelinase 2 and its relevant mechanisms may potentially be employed in cancer chemotherapies.

Simultaneous molecular formula determinations of natural compounds in a plant extract using 15 T Fourier transform ion cyclotron resonance mass spectrometry

BACKGROUND

Plant extracts are a reservoir of pharmacologically active substances; however, conventional analytical methods can analyze only a small portion of an extract. Here, we report a high-throughput analytical method capable of determining most phytochemicals in a plant extract and of providing their molecular formulae from a single experiment using ultra-high-resolution electrospray ionization mass spectrometry (UHR ESI MS). UHR mass profiling was used to analyze natural compounds in a 70% ethanol ginseng extract, which was directly infused into a 15 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer for less than 10 min without a separation process.

RESULTS

The UHR FT-ICR MS yielded a mass accuracy of 0.5 ppm and a mass resolving power (m/Δm) of 1,000,000-270,000 for the range m/z 290-1,100. The mass resolution was sufficient to resolve the isotopic fine structure (IFS) of many compounds in the extract. After noise removal from 1,552 peaks, 405 compounds were detected. The molecular formulae of 123 compounds, including 33 ginsenosides, were determined using the observed IFS, exact monoisotopic mass, and exact mass difference. Liquid chromatography (LC)/FT-ICR MS of the extract was performed to compare the high-throughput performance of UHR ESI FT-ICR MS. The LC/FT-ICR MS detected only 129 compounds, including 19 ginsenosides. The result showed that UHR ESI FT-ICR MS identified three times more compounds than LC/FT-ICR MS and in a relatively shorter time. The molecular formula determination by UHR FT-ICR MS was validated by LC and tandem MS analyses of three known ginsenosides.

CONCLUSIONS

UHR mass profiling of a plant extract by 15 T FT-ICR MS showed that multiple compounds were simultaneously detected and their molecular formulae were decisively determined by a single experiment with ultra-high mass resolution and mass accuracy. Simultaneous molecular determination of multiple natural products by UHR ESI FT-ICR MS would be a powerful method to profile a wide range of natural compounds.

Resolution of adefovir-related nephrotoxicity by adefovir dose-reduction in patients with chronic hepatitis B

BACKGROUND

Chronic hepatitis B patients (CHB) treated with adefovir were followed up to evaluate nephrotoxicity and its outcome.

AIM

To assess the incidence of renal dysfunction during adefovir therapy in Asian patients and factors associated with it, and evaluate strategies to improve adefovir-related renal dysfunction and their impact on viral suppression.

METHODS

Chronic hepatitis B clinic patients from a tertiary hospital on adefovir treatment, with their clinical and laboratory parameters were extracted from the hospital electronic clinical database in an observational study design. Patients were excluded if they had liver/renal transplant, baseline renal impairment or were on dialysis. Adefovir-related renal dysfunction was defined as adefovir-related abnormal serum creatinine (ARASC) > 125 μmol/L (males), >90 μmol/L (females); adefovir-related abnormal GFR <60 mL/min; and adefovir-related increased serum creatinine >0.5 mg/dL, without other known causes of nephrotoxicity.

RESULTS

A total of 271/383 adefovir-treated patients were suitable for analysis and 33(12%) patients developed abnormal serum creatinine. Cumulative increase in proportion of patients with ARASC was 33.8% and GFR ≤60 mL/min was 38.3% by 6 years, while serum creatinine increase ≥0.5 mg/dL was 21.48% by 5 years. Using multivariate analysis, the only independent baseline predictor of ARASC was GFR ≤76.1 mL/min. Patients who had ARASC had similar levels of viral suppression to those who did not have ARASC. Those who had ARASC either continued adefovir (24%), switched therapy (24%) or had adefovir dose reduction (52%). ARASC resolved and GFR normalised in almost all patients after either switching therapy or reducing adefovir dose, with no difference between the two strategies (P = 0.737). Those with adefovir dose reduction had no significant increase in HBV DNA (P = 0.170).

CONCLUSIONS

Adefovir-related renal dysfunction occurred in a significant number of adefovir-treated patients, but reduction of the dose led to renal improvement without compromising treatment efficacy.

Downregulation of cell-free miR-198 as a diagnostic biomarker for lung adenocarcinoma-associated malignant pleural effusion

Circulating cell-free microRNAs (miRNAs) are potential cancer biomarkers. The aim of this study was to identify miRNAs that are differentially expressed between benign pleural effusion (BPE) and lung adenocarcinoma-associated malignant pleural effusion (LA-MPE). The expression level of cell-free miRNA was investigated in 107 patients with pleural effusion. Microarrays were used to screen 160 miRNAs in a discovery set comprising 20 effusion samples (ten BPEs and ten LA-MPEs). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate the profiling results obtained for the discovery set and those obtained for a validation set comprising 42 BPEs and 45 LA-MPEs. The area under the receiver operating characteristic curve (AUC) was used to evaluate the diagnostic performance of the identified miRNAs and other common tumor markers, such as carcinoembryonic antigen (CEA) and cytokeratin fragment (CYFRA) 21-1. Microarray profiling showed that miR-198 was significantly downregulated in LA-MPE compared with BPE (p = 0.002). The miRNA microarray analysis results were confirmed by qRT-PCR (p < 0.001) using the validation set. The AUCs for miR-198, CEA and CYFRA 21-1 in the validation set were 0.887, 0.898 and 0.836, respectively. The diagnostic performance of miR-198 was comparable with that of CEA, but better than that of CYFRA 21-1. The AUC for all three markers combined was 0.926 (95% confidence interval, 0.843-0.973) with a sensitivity of 89.2% and a specificity of 85.0%. The present study suggests that cell-free miR-198 from patients with pleural effusion might have diagnostic potential for differentiating LA-MPE from BPE.

Anti-inflammatory mechanism of exogenous C2 ceramide in lipopolysaccharide-stimulated microglia

Ceramide is a major molecule among the sphingolipid metabolites which are produced in the brain and other organs and act as intracellular second messengers. Although a variety of physiological roles of ceramide have been reported in the periphery and central nervous systems, the role of ceramide in microglial activation has not been clearly demonstrated. In the present study, we examined the effects of exogenous cell permeable short chain ceramides on microglial activation in vitro and in vivo. We found that C2, C6, and C8 ceramide and C8 ceramide-1-phosphate inhibited iNOS and proinflammatory cytokines in lipopolysaccharide (LPS)-stimulated BV2 microglial cells and rat primary microglia. In addition, the administration of C2 ceramide suppressed microglial activation in the brains of LPS-exposed mice. By HPLC and LC/MS/MS analyses, we found that C2 ceramide on its own, rather than its modified form (i.e. ceramide-1-phosphate or long chain ceramides), mainly work by penetrating into microglial cells. Further mechanistic studies by using the most effective C2 ceramide among the short chain ceramides tested, revealed that C2 ceramide exerts anti-inflammatory effects via inhibition of the ROS, MAPKs, PI3K/Akt, and Jak/STAT pathways with upregulation of PKA and hemeoxygenase-1 expressions. Interestingly, we found that C2 ceramide inhibits TLR4 signaling by interfering with LPS and TLR4 interactions. Therefore, our data collectively suggests the therapeutic potential of short chain ceramides such as C2 for neuroinflammatory disorders such as Alzheimer's disease and Parkinson's disease.

The protective effects of oxyresveratrol imine derivative against hydrogen peroxide-induced cell death in PC12 cells

Oxyresveratrol (2',3,4',5-tetrahydroxystilbene) is a naturally occurring ingredient found in mulberries that shows potential as an antioxidant, anti-inflammatory, and neuroprotective agent. This study was performed to identify materials similar to oxyresveratrol that may have more effective antioxidant properties. We synthesized a stilbene analog referred to as Compound 1 (2',3,4',5-tetramethoxystilbene); a benzamide analog referred to as Compound 2 ((2,4-dimethoxyphenyl)-3,5-dimethoxybenzamide); and three imine analogs referred to as Compound 3 (3,5-dimethoxybenzylidene)-(2,4-dimethoxyphenylamine), Compound 4 ((4-methoxybenzylidene)-(3-methoxyphenyl)amine), and Compound 5 ((4-methoxybenzylidene)phenylamine). The cytoprotective effects of these compounds were subsequently evaluated using hydrogen peroxide-treated PC12 cells. The cytoprotective effects of the imine analogs were greater than the effects of oxyresveratrol and the other analogs at concentrations of 200 μM. The Compound 3, which is the most effective imine analog of oxyresveratrol, exhibited these cytoprotective effects against hydrogen peroxide-induced oxidative stress through the regulation of heme oxygenase-1 (HO-1) expression and the translocation of nuclear factor E2-related factor 2 (Nrf2). Our results suggest that imine analogs of oxyresveratrol may be useful agents in reducing neuronal oxidative damage.

Sulforaphane inhibits mitotic clonal expansion during adipogenesis through cell cycle arrest

Obesity is a risk factor for numerous metabolic disorders such as type 2 diabetes, hypertension, and coronary heart disease. Adipocyte differentiation is triggered by adipocyte hyperplasia, which leads to obesity. In this study, the inhibitory effect of sulforaphane, an isothiocyanate, on adipogenesis in 3T3-L1 cells was investigated. Sulforaphane decreased the accumulation of lipid droplets stained with Oil Red O and inhibited the elevation of triglycerides in the adipocytes (half-maximal inhibitory concentration = 7.3 µmol/l). The expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), major transcription factors for adipocyte differentiation, was significantly reduced by sulforaphane. The major effects of sulforaphane on the inhibition of adipocyte differentiation occurred during the early stage of adipogenesis. Thus, the expression of C/EBPβ, an early-stage biomarker of adipogenesis, decreased in a concentration-dependent manner when the adipocytes were exposed to sulforaphane (0, 5, 10, and 20 µmol/l). The proliferation of adipocytes treated with 20 µmol/l sulforaphane for 24 and 48 h was also suppressed. These results indicate that sulforaphane may specifically affect mitotic clonal expansion to inhibit adipocyte differentiation. Sulforaphane arrested the cell cycle at the G(0)/G(1) phase, increased p27 expression, and decreased retinoblastoma (Rb) phosphorylation. Additionally, sulforaphane modestly decreased the phosphorylation of ERK1/2 and Akt. Our results indicate that the inhibition of early-stage adipocyte differentiation by sulforaphane may be associated with cell cycle arrest at the G(0)/G(1) phase through upregulation of p27 expression.

Cardiomyocyte specific deficiency of serine palmitoyltransferase subunit 2 reduces ceramide but leads to cardiac dysfunction

The role of serine palmitoyltransferase (SPT) and de novo ceramide biosynthesis in cardiac ceramide and sphingomyelin metabolism is unclear. To determine whether the de novo synthetic pathways, rather than ceramide uptake from circulating lipoproteins, is important for heart ceramide levels, we created cardiomyocyte-specific deficiency of Sptlc2, a subunit of SPT. Heart-specific Sptlc2-deficient (hSptlc2 KO) mice had a >35% reduction in ceramide, which was limited to C18:0 and very long chain ceramides. Sphingomyelinase expression, and levels of sphingomyelin and diacylglycerol were unchanged. But surprisingly phospholipids and acyl CoAs contained increased saturated long chain fatty acids. hSptlc2 KO mice had decreased fractional shortening and thinning of the cardiac wall. While the genes regulating glucose and fatty acid metabolism were not changed, expression of cardiac failure markers and the genes involved in the formation of extracellular matrices were up-regulated in hSptlc2 KO hearts. In addition, ER-stress markers were up-regulated leading to increased apoptosis. These results suggest that Sptlc2-mediated de novo ceramide synthesis is an essential source of C18:0 and very long chain, but not of shorter chain, ceramides in the heart. Changes in heart lipids other than ceramide levels lead to cardiac toxicity.

Terpene alcohols inhibit de novo sphingolipid biosynthesis

The terpene alcohols geranyllinalool, phytol (diterpene alcohol), and farnesol (sesquiterpene alcohol) were newly found to inhibit sphingolipid de novo biosynthesis in LLC-PK₁ cells (pig kidney epithelial cells). A simple chromatographic bioassay was established for the screening of inhibitory compounds able to reduce the amount of sphinganine, an intermediate metabolite of sphingolipid biosynthesis. The screening strategy was based on the degree of suppression of fumonisin B₁ (FB₁-induced sphinganine accumulation following co-treatment with selected terpene alcohols. L-cycloserine and ISP-1, specific serine palmitoyltransferase (SPT) inhibitors, were used as positive controls. Our results show that measuring reduced sphinganine levels after treatment with 2 µM FB₁ in combination with the putative inhibitory compounds provides a useful screening bioassay for evaluating compounds causing sphingolipid depletion. Intracellular sphinganine concentrations were analyzed using the fluorescent peak areas of the O-phthalaldehyde (OPA) derivatives of sphinganine eluted with 87 % acetonitrile on a reversed-phase column. Geranyllinalool, phytol, and farnesol were identified as novel SPT inhibitors that reduce FB₁-induced sphinganine accumulation and thus inhibit the first step of sphingolipid de novo synthesis.

Evaluation of Urine Cytology in Urothelial Carcinoma Patients: A Comparison of CellprepPlus® Liquid-Based Cytology and Conventional Smear

BACKGROUND

Urine cytology is an important test in the screening of urothlelial neoplasms. The conventional smear (CS) method of testing urine samples has a low sensitivity, approximately 50% result accuracy for detecting urothelial carcinomas, while liquid-based cytology (LBC) has much improved diagnostic accuracy, sensitivity, and specificity. The aim of this study was to compare the morphologic features and diagnostic efficacy of CellprepPlus® LBC with those of CS for urine cytology.

METHODS

A total of 713 cases of urine specimens collected from November 2009 to September 2010 were included. All specimens were divided equally for the preparation of CellprepPlus® LBC and CS for each case.

RESULTS

CellprepPlus® revealed more cellularity, a cleaner background and better cytomorphologic features, but it showed a less intact architectural pattern compared to that of CS. Of the 88 histologically confirmed cases, the diagnostic sensitivity for CellprepPlus® was 50% and higher than the 37.5% for CS. The specificity of both preparations was 100%.

CONCLUSIONS

The CellprepPlus® showed an improved quality of slides and provided better diagnostic accuracy, thus CellprepPlus® could be a first-line screening tool in urinary tract cytology.

Association between the interleukin-18 promoter polymorphism and pulmonary tuberculosis in a Korean population

OBJECTIVE

To examine the role of the -667G/T, -618A/C and -148G/C single nucleotide polymorphisms in the promoter region of the human interleukin (IL) 18 gene in the development of pulmonary tuberculosis (PTB), and its radiographic characteristics and severity.

DESIGN

Differences in the allele and genotype distributions of the -667G/T, -618A/C, and -148G/C polymorphisms between 251 patients with PTB and 225 healthy controls, between patients with single- and multilobe involvement, and between patients with and without cavities were explored. Serum IL-18 levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

The -148G/G genotype was more common in patients with cavities than in those without (82.8% vs. 70.9%, P = 0.04), but an analogous trend was not observed for the -667G/T and -618A/C genotypes. However, there were no significant differences in allele and genotype distributions between patients with PTB and healthy controls, or between patients with single- and multilobe involvement (P > 0.05). Serum IL-18 levels were higher in patients with cavities (P = 0.01) and in patients with the -148G/G genotype (P = 0.02).

CONCLUSION

Considering serum IL-18 levels, the -148G/G genotype is associated with a cavitary formation of PTB rather than its development.

Methionine/galactose ratio on newborn blood spots useful for reduction of false positives for homocystinuria and galactosemia by high-performance anion-exchange chromatography with pulsed amperometric detection

BACKGROUND

Methionine (Met) in blood and urine is a useful diagnostic marker for homocystinuria (HCU). However, galactosemia could be misdiagnosed as HCU when Met is used as the sole marker, since elevated excretion of Met presents in both galactosemia and HCU. Use of a more specific diagnostic marker in addition to Met is therefore necessary for reduction of false positive results for HCU as well as confirmative diagnosis of HCU.

METHODS

Chromatographic separation was performed using an anion-exchange column. The levels of Met and galactose (Gal) on blood were measured and Met/Gal ratios were calculated from blood spot samples from 300 normal volunteers, eight galactosemia patients, and three HCU patients.

RESULTS

The Met/Gal ratio ranged 0-4.95 for normal blood spots (n=300), 0-0.22 for galactosemia samples (n=8), and >1250 for HCU patient samples.

CONCLUSIONS

Separation, extraction, and deproteinization procedures were established for Met and Gal in blood spots. And Met/Gal ratio allowed HCU to clearly distinguish from galactosemia. As a way of second tier confirmative analysis, the ratio is the best way to reduce false positives. The assay is most appropriate to reduce false positives in labs that do not screen for galactosemia.

Inverse relationship between adipocyte differentiation and ceramide level in 3T3-L1 cells

Adipocyte differentiation has been a target in anti-obesity strategies and is known to be closely related to lipid metabolism. Ceramide, a major sphingolipid metabolite, has been implicated in differentiation. In this study, we investigated whether ceramide biosynthesis is related to adipogenesis in 3T3-L1 cells. Preadipocytes can be differentiated synchronously by a mixture of adipogenic inducers including 3-isobutyl-1-methylxanthine, dexamethasone and insulin. The number of lipid droplets and the triglyceride content, which are differentiation biomarkers, gradually increased during adipogenesis. Interestingly, ceramide and sphingosine contents in the differentiated cells were decreased compared to those in preadipocytes. When the preadipocytes were treated with an 3-isobutyl-1-methylxanthine- or dexamethasone- or insulin-deficient mixture of inducers, the cellular ceramide levels were significantly increased compared with those in cells treated with the complete set of inducers. When preadipocytes were treated with 0, 0.1 or 1 µg/ml insulin along with 3-isobutyl-1-methylxanthine and dexamethasone, the ceramide levels were decreased and the triglyceride content was increased in a concentration-dependent manner. When the cells were treated with epigallocatechin gallate, an adipocyte differentiation inhibitor, during adipogenesis, the ceramide levels of adipocytes were increased and the fat content was decreased. In conclusion, our findings demonstrate that cellular ceramide levels are inversely correlated with adipocyte differentiation.

Simultaneous analysis method for polar and non-polar ginsenosides in red ginseng by reversed-phase HPLC-PAD

The paper describes the development of a simultaneous determination method for polar and non-polar ginsenosides in red ginseng with a reversed-phase high-performance liquid chromatography-pulsed amperometric detection method. This method could be applied directly without any pretreatment steps and enabled the performance of highly sensitive analysis within 1h. The detection (S/N=3) and quantification (S/N=10) limits for the ginsenosides ranged 0.02-0.10 ng and 0.1-0.3 ng, respectively. The linear regression coefficients ranged 0.9975-0.9998. Intra- and inter-day precisions were <9.91%. The mean recoveries ranged 98.08-103.06%. The total amount of ginsenosides in the hairy root of red ginseng was higher than that in the main root.