Shikonin upregulates the expression of drug-metabolizing enzymes and drug transporters in primary rat hepatocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Shikonin, a naphthoquinone pigment abundant in the root of the Chinese herb Lithospermum erythrorhizon, has been widely used to treat inflammatory diseases for thousands of years. Whether shikonin changes drug metabolism remains unclear.

AIM OF THE STUDY

We investigated whether shikonin modulates the expression of hepatic drug-metabolizing enzymes and transporters as well as the possible mechanisms of this action.

MATERIALS AND METHODS

Primary hepatocytes isolated from Sprague-Dawley rats were treated with 0-2 μM shikonin and the protein and mRNA levels of drug-metabolizing enzymes and transporters as well as the activation of aryl hydrocarbon receptor (AhR) and NF-E2-related factor 2 (Nrf2) were determined.

RESULTS

Shikonin dose-dependently increased the protein and RNA expression of phase I enzymes, i.e., cytochrome P450 (CYP) 1A1/2, CYP3A2, CYP2D1, and CYP2C6; phase II enzymes, i.e., glutathione S-transferase (GST), NADP(H) quinone oxidoreductase 1 (NQO1), and UDP glucuronosyltransferase 1A1; and phase III drug transporters, i.e., P-glycoprotein, multidrug resistance-associated protein 2/3, organic anion transporting polypeptide (OATP) 1B1, and OATP2B1. Immunoblot analysis and EMSA revealed that shikonin increased AhR and Nrf2 nuclear contents and DNA binding activity. AhR and Nrf2 knockdown by siRNA attenuated the ability of shikonin to induce drug-metabolizing enzyme expression. In addition, shikonin increased p38, JNK, and ERK1/2 phosphorylation, and inhibitors of the respective kinases inhibited shikonin-induced Nrf2 nuclear translocation.

CONCLUSIONS

Shikonin effectively upregulates the transcription of CYP isozymes, phase II detoxification enzymes, and phase III membrane transporters and this function is at least partially through activation of AhR and Nrf2. Moreover, Nrf2 activation is dependent on mitogen-activated protein kinases.

Andrographolide inhibits hypoxia-induced hypoxia-inducible factor 1α and endothelin 1 expression through the heme oxygenase 1/CO/cGMP/MKP-5 pathways in EA.hy926 cells

Andrographolide is a potent anti-inflammatory agent found in Andrographis paniculata. Endothelin 1 (ET-1) is an endothelium-derived vasoconstrictor with pro-inflammatory properties secreted in response to hypoxia. Mitogen-activated protein kinase phosphatase 5 (MKP-5) is a dual-specificity phosphatase that dephosphorylates threonine and tyrosine residues of MAPKs. We showed previously that hypoxia-induced HIF-1α expression and ET-1 secretion are dependent on p38 MAPK in EA.hy926 cells. Here, we investigate what role MKP-5 plays in andrographolide's inhibition of hypoxia-induced expression of HIF-1α and ET-1. Hypoxic conditions were created using the hypoxia-mimetic agent CoCl₂ . Andrographolide enhanced HO-1 and MKP-5 expression and cellular cGMP content in addition to inhibiting hypoxia-induced ROS generation. Concomitantly, the HO-1 byproduct CO and the cGMP analogue 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) increased MKP-5 expression, and pretreatment with CO and 8-Br-cGMP inhibited hypoxia-induced HIF-1α and ET-1 expression. Transfection of HO-1 siRNA or pretreatment with the HO-1 inhibitor ZnPP-9 or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a specific inhibitor of soluble guanylate cyclase, reduced andrographolide-induced MKP-5 expression. Moreover, silencing MKP-5 or treatment with the phosphatase inhibitor vanadate abrogated andrographolide's suppressing hypoxia-induced p38 MAPK activation and HIF-1α expression. The inhibition of hypoxia-induced HIF-1α and ET-1 expression by andrographolide is likely associated with HO-1/CO/cGMP/MKP-5 pathways, which is involved in inhibiting hypoxia-induced p38 MAPK activation.

Andrographolide Inhibits Oxidized LDL-Induced Cholesterol Accumulation and Foam Cell Formation in Macrophages

oxLDL is involved in the pathogenesis of atherosclerotic lesions through cholesterol accumulation in macrophage foam cells. Andrographolide, the bioactive component of Andrographis paniculata, possesses several biological activities such as anti-inflammatory, anti-oxidant, and anticancer functions. Scavenger receptors (SRs), including class A SR (SR-A) and CD36, are responsible for the internalization of oxLDL. In contrast, receptors for reverse cholesterol transport, including ABCA1 and ABCG1, mediate the efflux of cholesterol from macrophage foam cells. Transcription factor liver X receptor [Formula: see text] (LXR[Formula: see text] plays a key role in lipid metabolism and inflammation as well as in the regulation of ABCA1 and ABCG1 expression. Because of the contribution of inflammation to macrophage foam cell formation and the potent anti-inflammatory activity of andrographolide, we hypothesized that andrographolide might inhibit oxLDL-induced macrophage foam cell formation. The results showed that andrographolide reduced oxLDL-induced lipid accumulation in macrophage foam cells. Andrographolide decreased the mRNA and protein expression of CD36 by inducing the degradation of CD36 mRNA; however, andrographolide had no effect on SR-A expression. In contrast, andrographolide increased the mRNA and protein expression of ABCA1 and ABCG1, which were dependent on LXR[Formula: see text]. Andrographolide enhanced LXR[Formula: see text] nuclear translocation and DNA binding activity. Treatment with the LXR[Formula: see text] antagonist GGPP and transfection with LXR[Formula: see text] siRNA reversed the ability of andrographolide to stimulate ABCA1 and ABCG1 protein expression. In conclusion, inhibition of CD36-mediated oxLDL uptake and induction of ABCA1- and ABCG1-dependent cholesterol efflux are two working mechanisms by which andrographolide inhibits macrophage foam cell formation, which suggests that andrographolide could be a potential candidate to prevent atherosclerosis.

Andrographolide inhibits hypoxia-induced HIF-1α-driven endothelin 1 secretion by activating Nrf2/HO-1 and promoting the expression of prolyl hydroxylases 2/3 in human endothelial cells

Andrographolide, the main bioactive component of the medicinal plant Andrographis paniculata, has been shown to possess potent anti-inflammatory activity. Endothelin 1 (ET-1), a potent vasoconstrictor peptide produced by vascular endothelial cells, displays proinflammatory property. Hypoxia-inducible factor 1α (HIF-1α), the regulatory member of the transcription factor heterodimer HIF-1α/β, is one of the most important molecules that responds to hypoxia. Changes in cellular HIF-1α protein level are the result of altered gene transcription and protein stability, with the latter being dependent on prolyl hydroxylases (PHDs). In this study, inhibition of pro-inflammatory ET-1 expression and changes of HIF-1α gene transcription and protein stability under hypoxia by andrographolide in EA.hy926 endothelial-like cells were investigated. Hypoxic conditions were created using the hypoxia-mimetic agent CoCl_2. We found that hypoxia stimulated the production of reactive oxygen species (ROS), the expression of HIF-1α mRNA and protein, and the expression and secretion of ET-1. These effects, however, were attenuated by co-exposure to andrographolide, bilirubin, and RuCO. Silencing Nrf2 and heme oxygenase 1 (HO-1) reversed the inhibitory effects of andrographolide on hypxoia-induced HIF-1α mRNA and protein expression. Moreover, andrographolide increased the expression of prolyl hydroxylases (PHD) 2/3, which hydroxylate HIF-1α and promotes HIF-1α proteasome degradation, with an increase in HIF-1α hydroxylation was noted under hypoxia. Inhibition of p38 MAPK abrogated the hypoxia-induced increases in HIF-1α mRNA and protein expression as well as ET-1 mRNA expression and secretion. Taken together, these results suggest that andrographolide suppresses hypoxia-induced pro-inflammatory ET-1 expression by activating Nrf2/HO-1, inhibiting p38 MAPK signaling, and promoting PHD2/3 expression. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 918-930, 2017.

A Bayesian network meta-analysis comparing concurrent chemoradiotherapy followed by adjuvant chemotherapy, concurrent chemoradiotherapy alone and radiotherapy alone in patients with locoregionally advanced nasopharyngeal carcinoma

BACKGROUND

Given the lack of studies, whether the addition of adjuvant chemotherapy (AC) to concurrent chemoradiotherapy (CCRT) is superior to CCRT alone for locoregionally advanced nasopharyngeal carcinoma (NPC) remains unclear. The main objective of this Bayesian network meta-analysis was to determine the efficacy of CCRT + AC when compared with CCRT alone.

PATIENTS AND METHODS

We systematically searched databases and extracted data from randomized, controlled trials involving NPC patients randomly assigned to receive CCRT + AC, CCRT, or radiotherapy (RT). Overall survival (OS), locoregional recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) with hazard ratios (HRs) were investigated. A Bayesian network for different outcomes was established to incorporate all evidence. Multiple treatment comparisons based on the network integrated the efficacy of CCRT + AC, CCRT, and RT.

RESULTS

Eight studies involving 2144 patients were analyzed. In the network meta-analysis, CCRT + AC and CCRT were both significantly better than RT alone for all outcomes, except that no significant difference was found between CCRT and RT for LRFS. Though ranking probabilities showed that CCRT + AC was ranked superior to CCRT for OS, LRFS, and DMFS, no significant differences were found between CCRT+AC and CCRT for all outcomes [OS: HR = 0.86, 95% credible interval (CrI) 0.60-1.16; LRFS: HR = 0.72, 95% CrI 0.43-1.15; DMFS: HR = 0.86, 95% CrI 0.62-1.16].

CONCLUSIONS

No significant improvement was found following CCRT + AC compared with CCRT alone. Whether the omission of additional AC can reduce toxic effects without adversely affecting survival in patients with locoregionally advanced NPC should be further explored, in addition to the precise patient status that would benefit from AC following CCRT.

Docosahexaenoic acid inhibits vascular endothelial growth factor (VEGF)-induced cell migration via the GPR120/PP2A/ERK1/2/eNOS signaling pathway in human umbilical vein endothelial cells

Cell migration plays an important role in angiogenesis and wound repair. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that is essential for endothelial cell survival, proliferation, and migration. Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, shows both anti-inflammatory and antioxidant activities in vitro and in vivo. This study investigated the molecular mechanism by which DHA down-regulates VEGF-induced cell migration. HUVECs were used as the study model, and the MTT assay, Western blot, wound-healing assay, and phosphatase activity assay were used to explore the effects of DHA on cell migration. GPR120 is the putative receptor for DHA action. The results showed that DHA, PD98059 (an ERK1/2 inhibitor), and GW9508 (a GPR120 agonist) inhibited VEGF-induced cell migration. In contrast, pretreatment with okadaic acid (OA, a PP2A inhibitor) and S-nitroso-N-acetyl-DL-penicillamine (an NO donor) reversed the inhibition of cell migration by DHA. VEGF-induced cell migration was accompanied by phosphorylation of ERK1/2 and eNOS. Treatment of HUVECs with DHA increased PP2A enzyme activity and decreased VEGF-induced phosphorylation of ERK1/2 and eNOS. However, pretreatment with OA significantly decreased DHA-induced PP2A enzyme activity and reversed the DHA inhibition of VEGF-induced ERK1/2 and eNOS phosphorylation. These results suggest that stimulation of PP2A activity and inhibition of the VEGF-induced ERK1/2/eNOS signaling pathway may be involved in the DHA suppression of VEGF-induced cell migration. Thus, the effect of DHA on angiogenesis and wound repair is at least partly by virtue of its attenuation of cell migration.

An extended study of seroprevalence of anti-Anisakis simplex IgE antibodies in Norwegian blood donors

During the last decade, cases of the fish parasite Anisakis simplex infection and allergy in human have increased in countries with high fish consumption. Our aim was to perform an extended seroprevalence study of anti-IgE antibodies against this parasite in Norway, one of the high fish-consuming countries. At the Department of Immunology and Transfusion Medicine and the Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway, two main groups of anonymized serum samples were collected; the first (n = 993) from recently recruited blood donors (designated 'BDO') and the second (n = 414) from patient with total IgE levels ≥1000 kU/l (designated 'IGE+'). The sera were analysed by the ImmunoCAP(®) method for total IgE and IgE antibodies against A. simplex, house dust mite (HDM), shrimp, cod, crab, brine shrimp and shrimp tropomyosin. The A. simplex positive sera were further tested by an enzyme-linked immunosorbent assay (ELISA) method, which uses 2 recombinant (r) major allergens, rAni s 1 and rAni s 7 as target antigens. SDS-PAGE and Western immunoblotting analyses were also performed. Whereas the prevalences by ImmunoCAP(®) were 0.4% and 16.2% in the BDO and IGE+ groups, respectively, analyses with recombinant allergens showed only 0.0% and 0.2%. Cross-reactivity and immunoblotting analyses suggested that most of the ImmunoCAP(®) positive sera were probably false-positive due to cross-sensitization to shrimp and HDM. However, positivity due to other A. simplex antigens should also be considered. Compared with other high fish-consuming countries, we observed a very low seroprevalence of anti-Anisakis IgE antibodies in a Norwegian population.

Isothiocyanates protect against oxidized LDL-induced endothelial dysfunction by upregulating Nrf2-dependent antioxidation and suppressing NFκB activation

SCOPE

Oxidative stress plays a pivotal role in the pathophysiology of cardiovascular diseases. Oxidized low-density lipoprotein (oxLDL) is a key contributor to atherogenesis through multiple mechanisms. In this study, we investigated the protection by three structurally related isothiocyanates, i.e., sulforaphane (SFN), benzyl isothiocyanate (BITC), and phenethyl isocyanate (PEITC), against oxLDL-induced leukocyte adhesion to vascular endothelium and the mechanism involved.

METHODS AND RESULTS

The protection against oxLDL-induced endothelial dysfunction by isothiocyanates was studied in human umbilical vein endothelial cells (HUVECs). oxLDL increased reactive oxygen species (ROS) production, stimulated nuclear factor-kappaB (NFκB) activation, and enhanced intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and E-selectin expression in HUVECs, which led to promotion of monocyte adhesion to HUVECs. Treatment with SFN, BITC, and PEITC (0-10 μM) dose-dependently induced heme oxygenase (HO)-1, glutamate cysteine ligase (GCL) catalytic and modifier subunit expression, intracellular glutathione content, and antioxidant response element (ARE)-luciferase reporter activity. SFN, BITC, and PEITC pretreatment reversed oxLDL-induced ROS production, NFκB nuclear translocation, κB-reporter activity, ICAM-1, VCAM-1, and E-selectin expression, and monocyte adhesion to endothelial cells. Both heme oxygenase 1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) knockdown attenuated the isothiocyanate inhibition of oxLDL-induced ROS production, κB-reporter activity, and adhesion molecule expression.

CONCLUSION

SFN, BITC, and PEITC protect against oxLDL-induced endothelial damage by upregulating Nrf2-dependent HO-1 and GCL expression, which leads to inhibition of NFκB activation and ICAM-1, VCAM-1, and E-selectin expression.

Activation of Nrf2 is required for up-regulation of the π class of glutathione S-transferase in rat primary hepatocytes with L-methionine starvation

Numerous genes expression is regulated in response to amino acid shortage, which helps organisms adapt to amino acid limitation. The expression of the π class of glutathione (GSH) S-transferase (GSTP), a highly inducible phase II detoxification enzyme, is regulated mainly by activates activating protein 1 (AP-1) binding to the enhancer I of GSTP (GPEI). Here we show the critical role of nuclear factor erythroid-2-related factor 2 (Nrf2) in up-regulating GSTP gene transcription. Primary rat hepatocytes were cultured in a methionine-restricted medium, and immunoblotting and RT-PCR analyses showed that methionine restriction time-dependently increased GSTP protein and mRNA expression over a 48 h period. Nrf2 translocation to the nucleus, nuclear proteins binding to GPEI, and antioxidant response element (ARE) luciferase reporter activity were increased by methionine restriction as well as by l-buthionine sulfoximine (BSO), a GSH synthesis inhibitor. Transfection with Nrf2 siRNA knocked down Nrf2 expression and reversed the methionine-induced GSTP expression and GPEI binding activity. Chromatin immunoprecipitation assay confirmed the binding of Nrf2 to the GPEI. Phosphorylation of extracellular signal-regulated kinase 2 (ERK2) was increased in methionine-restricted and BSO-treated cells. ERK2 siRNA abolished methionine restriction-induced Nrf2 nuclear translocation, GPEI binding activity, ARE-luciferase reporter activity, and GSTP expression. Our results suggest that the up-regulation of GSTP gene transcription in response to methionine restriction likely occurs via the ERK-Nrf2-GPEI signaling pathway.

Imatinib mesylate alleviates diarrhea in a mouse model of intestinal allergy

BACKGROUND

When sensitized epicutaneously and challenged orally with ovalbumin, Balb/c mice develop allergen-induced diarrhea. As mast cells play important roles in diarrhea, we studied whether allergic diarrhea could be alleviated with imatinib mesylate.

METHODS

Balb/c mice were sensitized and challenged with ovalbumin and treated orally with imatinib. Cytokine mRNA expressions were determined with quantitative RT-PCR and numbers of small intestinal mast cells determined by staining for chloroacetate esterase and mucosal mast cell protease-1. Immunofluorescence staining was used to assess the intestinal CCL1 expression.

KEY RESULTS

Ovalbumin-sensitized and challenged Balb/c mice developed diarrhea, which was associated with increased number of mast cells and expression of interleukin (IL)-4 and -13, and chemokines CCL1 and CCL17 in the small intestine. Treatment with imatinib reduced the incidence of diarrhea, inhibited the development of mastocytosis and jejunal mRNA expression of IL-13, CCL1, CCL17 and CCL22. Mast cell-deficient W/W(-V) mice, and surprisingly, also their mast cell-competent control (+/+) littermates failed to develop diarrhea as a response to ovalbumin. This strain-dependent difference was associated with the inability of +/+ and W/W(-V) mice to increase the number of intestinal mast cells and expression of IL-4, IL-13, CCL1 and CCL17 after ovalbumin challenge.

CONCLUSIONS & INFERENCES

Development of allergic diarrhea is associated with the ability of mice to develop intestinal mastocytosis. Imatinib inhibited the development of intestinal mastocytosis, reduced the incidence of diarrhea, and reduced the expression of IL-13, CCL1, and CCL17. Targeting intestinal mast cells could be a feasible approach to treat allergic diarrhea.

IgE sensitization to the fish parasite Anisakis simplex in a Norwegian population: a pilot study

The reports on fish parasite Anisakis simplex allergy have increased in countries with high fish consumption in the last decade. In Norway, a high consumption country, the prevalence of immunoglobulin E (IgE) sensitization to A. simplex was still unknown. Thus, our objective was to investigate the sensitization prevalence in this country. At the Haukeland University Hospital, Bergen, Norway, two main groups of surplus serum samples were collected: one from newly recruited blood donors (BDO) and the other from the Allergy laboratory (ALL) after analysing IgE and IgE antibodies. The latter was divided into three series: one containing unsorted sera and two sorted by either Phadiatop(®) ≥0.35 kU(A)/l or total IgE ≥1000 kU/l. The sera were analysed for total IgE and IgE antibodies against A. simplex, shrimp, house dust mite (HDM), cod and cross-reactive carbohydrates (CCDs). The prevalence of IgE sensitization to A. simplex was 2.0%, 2.2% and 6.6% in BDO, the unsorted and Phadiatop(®) positive serum groups, respectively. A considerable degree of cross-sensitization to shrimp and HDM is further suggested. Unspecific binding because of high total IgE or by binding to CCDs seemed to play a minor role. The prevalence of IgE sensitization to A. simplex appears to be lower in a Norwegian population than in other high fish-consuming countries, but might still be overestimated owing to cross-sensitization.

Induction of glutathione synthesis and heme oxygenase 1 by the flavonoids butein and phloretin is mediated through the ERK/Nrf2 pathway and protects against oxidative stress

Butein and phloretin are chalcones that are members of the flavonoid family of polyphenols. Flavonoids have well-known antioxidant and anti-inflammatory activities. In rat primary hepatocytes, we examined whether butein and phloretin affect tert-butylhydroperoxide (tBHP)-induced oxidative damage and the possible mechanism(s) involved. Treatment with butein and phloretin markedly attenuated tBHP-induced peroxide formation, and this amelioration was reversed by l-buthionine-S-sulfoximine [a glutamate cysteine ligase (GCL) inhibitor] and zinc protoporphyrin [a heme oxygenase 1 (HO-1) inhibitor]. Butein and phloretin induced both HO-1 and GCL protein and mRNA expression and increased intracellular glutathione (GSH) and total GSH content. Butein treatment activated the ERK1/2 signaling pathway and increased Nrf2 nuclear translocation, Nrf2 nuclear protein-DNA binding activity, and ARE-luciferase reporter activity. The roles of the ERK signaling pathway and Nrf2 in butein-induced HO-1 and GCL catalytic subunit (GCLC) expression were determined by using RNA interference directed against ERK2 and Nrf2. Both siERK2 and siNrf2 abolished butein-induced HO-1 and GCLC protein expression. These results suggest the involvement of ERK2 and Nrf2 in the induction of HO-1 and GCLC by butein. In an animal study, phloretin was shown to increase GSH content and HO-1 expression in rat liver and decrease carbon tetrachloride-induced hepatotoxicity. In conclusion, we demonstrate that butein and phloretin up-regulate HO-1 and GCL expression through the ERK2/Nrf2 pathway and protect hepatocytes against oxidative stress.

Inhibition of TNF-α-Induced Inflammation by andrographolide via down-regulation of the PI3K/Akt signaling pathway

Andrographolide (1), an active constituent of Andrographis paniculata, decreased tumor necrosis factor-α (TNF-α)-induced intercellular adhesion molecule-1 (ICAM-1) expression and adhesion of HL-60 cells onto human umbilical vein endothelial cells (HUVEC), which are associated with inflammatory diseases. Moreover, 1 abolished TNF-α-induced Akt phosphorylation. Transfection of an activated Akt1 cDNA vector increased Akt phosphorylation and ICAM-1 expression like TNF-α. In addition, 1 and LY294002 blocked TNF-α-induced IκB-α degradation and nuclear p65 protein accumulation, as well as the DNA-binding activity of NF-κB. Compound 1 exhibits anti-inflammatory properties through the inhibition of TNF-α-induced ICAM-1 expression. The anti-inflammatory activity of 1 may be associated with the inhibition of the PI3K/Akt pathway and downstream target NF-κB activation in HUVEC cells.

Oxidative modifications of proteins by sodium arsenite in human umbilical vein endothelial cells

Epidemiologic studies have demonstrated that chronic arsenic exposure is associated with the incidence of chronic diseases. This association is partly related to the increase in reactive oxygen species (ROS) overload and protein oxidation that result from arsenic exposure. In this study, we intended to identify proteins susceptible to oxidative carbonylation by sodium arsenite and the impact of carbonylation on the function of these proteins in human umbilical vein endothelial cells (HUVECs). The 2,4-dinitrophenylhydrazine (DNPH) dot-blot assay revealed that arsenite (0-50 μM) dose-dependently increased protein carbonylation. Consistent with these findings, the cellular ROS level as measured by 2',7'-dichlorofluorescein diacetate (DCHF-DA) assay was increased in cells exposed to arsenite. By two-dimensional gel electrophoresis and matrix assist laser desorption ionization time of flight mass spectrometry (MALDI-TOF/MS), one glycolytic enzyme, enolase-α, two cytoskeleton proteins, fascin (F-actin associated protein) and vimentin, and two protein quality control proteins, HSC70 (heat-shock cognate protein 70), and PDIA3 (protein disulfide isomerase family A, member 3) were identified to be arsenic-sensitive carbonlyated proteins. Accompanied by carbonylation, enolase-α activity was dose-dependently decreased and the F-actin filament network was disturbed. Taken together, our results suggest that arsenite exposure results in the generation of carbonylated proteins, and the resultant changes in energy metabolism and in the cytoskeletal network may partly lead to cell damage.

Sulforaphane and alpha-lipoic acid upregulate the expression of the pi class of glutathione S-transferase through c-jun and Nrf2 activation

The anticarcinogenic effect of dietary organosulfur compounds has been partly attributed to their modulation of the activity and expression of phase II detoxification enzymes. Our previous studies indicated that garlic allyl sulfides upregulate the expression of the pi class of glutathione S-transferase (GSTP) through the activator protein-1 pathway. Here, we examined the modulatory effect of sulforaphane (SFN) and alpha-lipoic acid (LA) or dihydrolipoic acid (DHLA) on GSTP expression in rat Clone 9 liver cells. Cells were treated with LA or DHLA (50-600 micromol/L) or SFN (0.2-5 micromol/L) for 24 h. Immunoblots and real-time PCR showed that SFN, LA, and DHLA dose dependently induced GSTP protein and mRNA expression. Compared with the induction by the garlic organosulfur compound diallyl trisulfide (DATS), the effectiveness was in the order of SFN > DATS > LA = DHLA. The increase in GSTP enzyme activity in cells treated with 5 micromol/L SFN, 50 micromol/L DATS, and 600 micromol/L LA and DHLA was 172, 75, 122, and 117%, respectively (P < 0.05). A reporter assay showed that the GSTP enhancer I (GPEI) was required for GSTP induction by the organosulfur compounds. Electromobility gel shift assays showed that the DNA binding of GPEI to nuclear proteins reached a maximum at 0.5-1 h after SFN, LA, and DHLA treatment. Super-shift assay revealed that the transcription factors c-jun and nuclear factor erythroid-2 related factor 2 (Nrf2) were bound to GPEI. These results suggest that SFN and LA in either its oxidized or reduced form upregulate the transcription of the GSTP gene by activating c-jun and Nrf2 binding to the enhancer element GPEI.

Anti-Inflammatory effects of antidepressants through suppression of the interferon-gamma/interleukin-10 production ratio

There is some evidence that major depression--in particular, treatment-resistant depression (TRD)--is accompanied by activation of the inflammatory response system and that proinflammatory cytokines may play a role in the etiology of depression. This study was carried out to examine the effects of antidepressive agents, i.e., imipramine, venlafaxine, L-5-hydroxytryptophan, and fluoxetine on the production of interferon-gamma (IFN-gamma), a proinflammatory cytokine, and interleukin-10 (IL-10), a negative immunoregulatory cytokine. Diluted whole blood of fluoxetine-treated patients with TRD (mean age, 50.6+/-3.9 years) and age-matched healthy controls (mean age, 51.6+/-1.7 years) and younger healthy volunteers (mean age, 35.4+/-9.6 years) was stimulated with phytohemagglutinin (1 microg/mL) and lipopolysaccharide (5 microg/mL) for 48 hours with and without incubation with the antidepressants at 10-6 M and 10(-5) M. IFN-gamma and IL-10 were quantified by means of enzyme-linked immunoassays. The ratio of IFN-gamma to IL-10 production by immunocytes was computed because this ratio is of critical importance in determining the capacity of immunocytes to activate or inhibit monocytic and T-lymphocytic functions. All four antidepressive drugs significantly increased the production of IL-10. Fluoxetine significantly decreased the production of IFN-gamma. All four antidepressants significantly reduced the IFN-gamma/IL-10 ratio. There were no significant differences in the antidepressant-induced changes in IFN-gamma or IL-10 between younger and older healthy volunteers and TRD patients. Tricyclic antidepressants, selective serotonin reuptake inhibitors, and serotonin-noradrenaline reuptake inhibitors, as well as the immediate precursor of serotonin, have a common, negative immunoregulatory effect by suppressing the IFN-gamma/IL-10 production ratio. It is suggested that the therapeutic efficacy of antidepressants may be related to their negative immunoregulatory effects.

Receptor-specific targeting mediated by the coexpression of a targeted murine leukemia virus envelope protein and a binding-defective influenza hemagglutinin protein

The entry of retroviral vectors into cells requires two events: binding to a cell surface receptor and the subsequent fusion of viral and cellular membranes. The host range of a vector is therefore determined largely by the receptor specificity of the fusion protein contained in the outer viral envelope. Previous attempts to generate targeted retroviral vectors have included the addition of targeting ligands to the murine leukemia virus envelope protein (MuLV Env). Although such proteins frequently display modified cell-binding characteristics, the interaction with the targeted receptors fails to trigger virus-cell fusion. Here, we report the use of a binding-defective but fusion-competent hemagglutinin (HA) protein to complement the fusion defect in a chimeric MuLV Env targeted to the Flt-3 receptor. Retroviral vectors containing both proteins showed enhanced transduction of cells expressing Flt-3, which was abrogated by preincubating the target cells with soluble Flt-3 ligand. Furthermore, the fusion function of HA was absolutely required. These data demonstrate that it is possible to separate the binding and fusion events of retroviral entry, using two separate proteins, and suggest that varying the binding protein component in this scheme may allow a general strategy for targeting retroviral vectors.

Peripheral markers of serotonergic and noradrenergic function in post-pubertal, caucasian males with autistic disorder

Some studies have suggested that disorders in the peripheral and central metabolism of serotonin (5-HT) and noradrenaline may play a role in the pathophysiology of autistic disorder. This study examines serotonergic and noradrenergic markers in a study group of 13 male, post-pubertal, caucasian autistic patients (age 12-18 y; I.Q. > 55) and 13 matched volunteers. [3H]-paroxetine binding Kd values were significantly higher in patients with autism than in healthy volunteers. Plasma concentrations of tryptophan, the precursor of 5-HT, were significantly lower in autistic patients than in healthy volunteers. There were no significant differences between autistic and normal children in the serum concentrations of 5-HT, or the 24-hr urinary excretion of 5-hydroxy-indoleacetic acid (5-HIAA), adrenaline, noradrenaline, and dopamine. There were no significant differences in [3H]-rauwolscine binding Bmax or Kd values, or in the serum concentrations of tyrosine, the precursor of noradrenaline, between both study groups. There were highly significant positive correlations between age and 24-hr urinary excretion of 5-HIAA and serum tryptophan. The results suggest that: 1) serotonergic disturbances, such as defects in the 5-HT transporter system and lowered plasma tryptophan, may play a role in the pathophysiology of autism; 2) autism is not associated with alterations in the noradrenergic system; and 3) the metabolism of serotonin in humans undergoes significant changes between the ages of 12 and 18 years.

Immune activation in the early puerperium is related to postpartum anxiety and depressive symptoms

The pathophysiology of the postpartum blues, common transient mood disorders in the first week postpartum, has remained elusive. Recently, however, it has been shown that depression and anxiety disorders are accompanied by activation of the inflammatory response system (IRS). This study was developed to determine whether the postnatal blues is associated with IRS activation. Serum concentrations of interleukin-6 (IL-6), IL-6 receptor (IL-6R), gp130 (the IL-6 signaling protein), IL-1R antagonist (IL-1RA) and leukemia inhibitory factor receptor (LIFR) were assayed in 22 nonpregnant women and in 91 pregnant women before delivery and 1 and 3 days after delivery. On each occasion the parturient women completed the State version of the Spielberger State-Trait-Anxiety-Inventory (STAI) and the Zung Depression Rating Scale (ZDS). Serum IL-6, IL-1RA and LIFR were significantly higher in pregnant women at the end of term than in nonpregnant women.

The immune-inflammatory pathophysiology of fibromyalgia: increased serum soluble gp130, the common signal transducer protein of various neurotrophic cytokines

Fibromyalgia is a chronic, painful musculoskeletal disorder characterized by widespread pain, pressure hyperalgesia, morning stiffness and by an increased incidence of depressive symptoms. The etiology, however, has remained elusive. The aim of the present study was to examine the inflammatory response system (IRS) in fibromyalgia. Serum interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), sgp130, sIL-1R antagonist (IL-1RA) and sCD8 were determined in 33 healthy volunteers and in 21 fibromyalgia patients, classified according to the American College of Rheumatology criteria. Severity of illness was measured with several pain scales, dolorimetry and the Hamilton Depression Rating Scale (HDRS). Serum sgp130 was significantly higher and serum sCD8 significantly lower in fibromyalgia patients than in healthy volunteers. Serum sIL-6R and sIL-1RA were significantly higher in fibromyalgia patients with an increased HDRS score (> or = 16) than in normal volunteers and fibromyalgia patients with a HDRS score < 16. In fibromyalgia patients, an important part of the variance in sCD8 (50.3%) and IL-1RA (19.3%) could be explained by the HDRS score; 74.3% of the variance in sIL-6R was explained by the combined effects of pain symptoms and the HDRS score; and 25.9% of the variance in serum sgp130 was explained by stiffness. The results support the contention that pain and stiffness in fibromyalgia may be accompanied by a suppression of some aspects of the IRS and that the presence of clinically significant depressive symptoms in fibromyalgia is associated with some signs of IRS activation.

Negative immunoregulatory effects of antidepressants: inhibition of interferon-gamma and stimulation of interleukin-10 secretion

There is now some evidence that major depression is accompanied by activation of the inflammatory response system. There is also some evidence that antidepressants may suppress the release of cytokines, such as interleukin-1 beta (IL-1 beta) and IL-6 by activated monocytes and IL-2 and interferon-gamma (IFN gamma) by activated T cells. This study was carried out to examine the effects of clomipramine, sertraline, and trazodone on the stimulated production of IFN gamma, a pro-inflammatory cytokine, and IL-10, a negative immunoregulatory cytokine. Whole blood of nine healthy volunteers was stimulated with PHA, 5 micrograms/mL and LPS, 25 micrograms/mL for 72 hr with and without incubation with clomipramine, 10(-6) and 10(-9) M, sertraline, 10(-6) and 10(-8) M, and trazodone, 10(-6) and 10(-8) M. All three antidepressants significantly reduced IFN gamma secretion, whereas clomipramine and sertraline significantly increased IL-10 secretion in culture supernatant. All three antidepressants significantly reduced the IFN gamma/IL-10 ratio. The results suggest that antidepressants, at concentrations in the therapeutical range, have negative immunoregulatory effects through inhibition of IFN gamma and stimulation of IL-10 release.

Elevated serum interleukin-6 (IL-6) and IL-6 receptor concentrations in posttraumatic stress disorder following accidental man-made traumatic events

BACKGROUND

Recently, it has been reported that serum interleukin-1 beta (IL-1 beta), but not soluble IL-2 receptor (sIL-2R), concentrations were significantly higher in patients with posttraumatic stress disorder (PTSD) than in normal volunteers, and that psychological stress in humans is associated with increased secretion of proinflammatory cytokines, such as IL-6.

METHODS

The aim of the present study was to examine the inflammatory response system in patients with PTSD through measurements of serum IL-6, sIL-6R, sgp130 (the IL-6 signal transducing protein), sIL-1R antagonist (sIL-1RA; an endogenous IL-1 receptor antagonist), CC16 (an endogenous anticytokine), and sCD8 (the T suppressor-cytotoxic antigen).

RESULTS

Serum IL-6 and sIL-6R, but not sgp130, sIL-RA, CC16, or sCD8, concentrations were significantly higher in PTSD patients than in normal volunteers. Serum sIL-6R concentrations were significantly higher in PTSD patients with concurrent major depression than in PTSD patients without major depression and normal volunteers. There were no significant relationships between serum IL-6 or sIL-6R and severity measures of PTSD.

CONCLUSIONS

The results suggest that PTSD is associated with increased IL-6 signaling. It is hypothesized that stress-induced secretion of proinflammatory cytokines is involved in the catecholaminergic modulation of anxiety reactions.

In vitro immunoregulatory effects of lithium in healthy volunteers

RATIONALE

There is now some evidence that major depression is associated with activation of the inflammatory response system (IRS). Lithium is effective in the treatment and prophylaxis of major depression and shows significant immunoregulatory functions.

OBJECTIVE

The aims of the present study were to examine the in vitro effects of lithium on the unstimulated and lipolysaccharide (LPS) + phytohemagglutinin (PHA)-induced production of proinflammatory cytokines, such as interleukin-6 (IL-6), IL-8, tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma), and negative immunoregulatory cytokines or proteins, such as IL-10 and the IL-1 receptor antagonist (IL-1RA).

METHODS

The in vitro effects of lithium carbonate at low (10(-4) M and 10(-5) M) and therapeutic (10(-3) M) concentrations on the above cytokines and the IL-1RA were examined in nine healthy volunteers on whole blood supernatant cultured for 72 h.

RESULTS

Lithium (10(-3) M) in the presence of LPS+PHA significantly increased the stimulated production of IFNgamma, IL-8, TNFalpha, IL-1RA and IL-10. Lithium (10(-3) M) significantly increased the unstimulated production of IL-8 and IL-10.

CONCLUSIONS

The results suggest that lithium has significant immunoregulatory effects by increasing the production of both proinflammatory cytokines (IFNgamma, TNFalpha and IL-8) and negative immunoregulatory cytokines or proteins (IL-10 and the IL-1RA).

Higher serum prolyl endopeptidase activity in patients with post-traumatic stress disorder

BACKGROUND

It is reported that psychiatric disorders, such as depression and schizophrenia, are associated with changes in serum activity of prolyl endopeptidase (EC 3.4.21.26), a cytosolic endopeptidase, which cleaves peptide bonds on the carboxylside of proline in proteins of relatively small molecular mass.

AIMS AND METHODS

The aims of the present study were to examine serum PEP activity in patients with post-traumatic stress disorder (PTSD) versus healthy volunteers. PEP activity has been determined by a fluorimetric assay.

RESULTS

Serum PEP activity was significantly higher in patients with PTSD than in normal volunteers. Serum PEP activity was significantly higher in patients with PTSD and concurrent major depression than in patients with PTSD without major depression. In PTSD patients, there were no significant correlations between serum PEP activity and severity of PTSD symptoms.

CONCLUSIONS

The results show that PTSD and, in particular, PTSD with concurrent major depression is associated with increased activity of PEP.

RELEVANCE

these results may be of importance for the (i) neuroendocrine pathophysiology of PTSD since PEP degrades neuropeptides, such as arginine vasopressin (AVP) and thyrotropin releasing hormone (TRH); and (ii) etiology of PTSD, since PEP degrades behaviorally active neuropeptides, such as AVP, TRH, oxytocin, neurotensin and substance P, which play a key role in positive reinforcement, social interactions, emotions and stress responsivity.

Serotonergic and noradrenergic markers of post-traumatic stress disorder with and without major depression

Some studies have suggested that disorders in the peripheral and central metabolism of serotonin (5-HT) and noradrenaline (NE) may play roles in the pathophysiology of post-traumatic stress disorder (PTSD). This study examines (1) the availability of plasma total tryptophan, the precursor of 5-HT, and tyrosine, the precursor of NE; and (2) the platelet 5-HT transporter and alpha 2-adrenoceptor (alpha 2-AR) binding sites in patients with PTSD and healthy volunteers. High-performance liquid chromatography (HPLC) was employed to measure plasma tryptophan and tyrosine as well as amino acids known to compete with the same cerebral transport system; that is, valine, leucine, phenylalanine, and isoleucine. The maximum number of binding sites (Bmax) and their affinity (Kd) for binding to [3H]-paroxetine and [3H]-rauwolscine, a selective alpha 2-AR antagonist, were determined. [3H]-paroxetine and [3H]-rauwolscine binding Kd values were significantly higher in patients with PTSD than in healthy volunteers. [3H]-rauwolscine binding Kd values were significantly higher in patients with PTSD and concurrent major depression (MD) than in PTSD patients without MD and healthy volunteers. Plasma tyrosine concentrations and the ratio of tyrosine/valine + leucine + isoleucine + phenylalanine + tryptophan were significantly higher in PTSD patients with MD than in those without MD and healthy volunteers. The results show that PTSD is accompanied by lower affinity of paroxetine binding sites and that PTSD with concurrent MD is accompanied by lower affinity of alpha 2-ARs and increased plasma tyrosine availability to the brain. The results suggest that (1) serotonergic mechanisms, such as defects in the 5-HT transporter system, may play a role in the pathophysiology of PTSD; and (2) that catecholaminergic mechanisms, such as increased precursor availability and lowered affinity of alpha 2-ARs, may play a role in the pathophysiology of PTSD with concurrent MD.

Persistence of the interaction of calmodulin with adenylyl cyclase: implications for integration of transient calcium stimuli

Ca2+/calmodulin-sensitive adenylyl cyclase plays a role in several forms of synaptic plasticity and learning. To understand how cellular signals from neuronal activity during behavioral stimuli might be integrated by adenylyl cyclase, we have characterized the response of type I adenylyl cyclase to transient Ca2+ stimuli. Stimulation by a several second Ca2+ stimulus is delayed, rising to a peak after the Ca2+ stimulus has ended. We attempted to identify the site of the persistent Ca2+ signal that enabled adenylyl cyclase stimulation to increase after free Ca2+ had declined. Free calmodulin itself displayed no persistent activation by Ca2+ and was unable to activate adenylyl cyclase if exposed to low Ca2+ solution <1 s before reaching adenylyl cyclase. In contrast, activation of the calmodulin-adenylyl cyclase complex persisted for seconds after Ca2+ stimulus. Activation decayed with a time constant of 6 or 13 s depending on assay conditions. These results suggest that the calmodulin-adenylyl cyclase complex can serve as a site of cellular memory for a Ca2+ transient that has ended even before adenylyl cyclase is fully activated.

Sequence-dependent interactions between transient calcium and transmitter stimuli in activation of mammalian brain adenylyl cyclase

Recent evidence implicates Ca2+/CaM-sensitive adenylyl cyclase (AC) as a molecular coincidence detector for temporally paired stimuli during associative learning. During conditioning in Aplysia, AC is optimally activated when Ca2+ influx, the cellular signal for the conditioned stimulus (CS), precedes binding of modulatory transmitter, the cellular signal for the unconditioned stimulus (US). This sequence preference of the AC for Ca2+-before-transmitter, parallels the CS-preceding-US pairing requirement of classical conditioning. In this study, we have examined the response of AC from rat cerebellum to brief exposures to Ca2+ and to transmitter in a perfused membrane assay. We observed modest synergism between Ca2+ and transmitter in activating AC. Activation was more effective when a Ca2+ stimulus immediately preceded a transmitter stimulus than when the two stimuli were delivered in the reverse order. Thus, rat cerebellar AC displayed a sequence preference for optimal activation by paired stimuli similar to that observed in Aplysia; this sequence dependence could contribute to the CS-US sequence requirement observed in most mammalian classical conditioning paradigms.

Lower serum activity of prolyl endopeptidase in fibromyalgia is related to severity of depressive symptoms and pressure hyperalgesia

BACKGROUND

The aims of the present study were to examine serum activities of peptidases, i.e. prolyl endopeptidase (PEP) and dipeptidyl peptidase IV (DPP IV), in patients with fibromyalgia and to examine the effects of subchronic treatment with sertraline on these variables.

METHOD

Serum PEP and DPP IV activity were measured in 28 normal volunteers and 21 fibromyalgia patients, classified according to the American College of Rheumatology criteria. Tenderness at tender points was evaluated by means of dolorimetry. Fibromyalgia patients had repeated measurements of serum PEP and DPP IV both before and after repeated administration of sertraline or placebo for 12 weeks.

RESULTS

Patients with fibromyalgia had significantly lower serum PEP activity than normal volunteers. There were significantly negative correlations between serum PEP activity and severity of pressure hyperalgesia and the non-somatic, cognitive symptoms of the Hamilton Depression Rating Scale. Fibromyalgia patients with severe pressure hyperalgesia had significantly lower PEP activity than normal controls and fibromyalgia patients with less severe hyperalgesia. Fibromyalgia patients with severe non-somatic depressive symptoms had significantly lower serum PEP activity than normal volunteers. There were no significant changes in serum DPP IV activity in fibromyalgia. There were no significant effects of repeated administration of sertraline on serum PEP and DPP IV activity in patients with fibromyalgia.

CONCLUSIONS

The results show that fibromyalgia, and aberrant pain perception and depressive symptoms in fibromyalgia are related to lower serum PEP activity. It is hypothesized that lower serum PEP activity may play a role in the biophysiology of fibromyalgia through diminished inactivation of algesic and depression-related peptides.

Virtually 100% of melanoma cell lines harbor alterations at the DNA level within CDKN2A, CDKN2B, or one of their downstream targets

The cyclin-dependent kinase inhibitor 2A (CDKN2A), or p16INK4a, gene on 9p21 is important in the genesis of both familial and sporadic melanoma. Homozygous deletions and intragenic mutations of this gene have been identified in both melanoma cell lines and uncultured tumors, although the frequency of these alterations is higher in the cell lines. A proportion of melanoma cell lines and tumors without deletion/mutation of CDKN2A have also been determined to harbor transcriptionally inactive CDKN2A alleles or carry alterations in other components of the pathway through which p16INK4a acts on pRb to mediate cell cycle arrest. We sought to determine the frequency of these alternative events (in relationship to those that specifically inactivate CDKN2A) in a panel of 45 melanoma cell lines. Surprisingly, at the DNA level alone, 96% (43/45) of melanoma cell lines examined were found to be deleted/mutated/methylated for CDKN2A (34/45), homozygously deleted for CDKN2A's neighbor and homolog CDKN2B (6/45), and/or mutated/amplified for CDK4 (5/45). In two of these 43 cases, homozygous deletions of CDKN2A were detected along with a CDK4 mutation or amplification of the cyclin D1 (CCND1) gene. The latter discoveries were made in two of three cell lines which harbored extremely large (3-6 Mb) homozygous deletions on 9p21; all other homozygous deletions in similarly affected cell lines (N = 23) were confined to a region immediately surrounding the CDKN2A/CDKN2B loci. These results suggest that (1) only melanoma cells with alterations in this pathway can be propagated in culture, and (2) the homozygous deletions on 9p21 in the cell lines, which are also mutated/amplified for CDK4 or CCND1, could serve to target tumor suppressor genes other than CDKN2A.

Isolation and sequence analysis of a human cDNA clone (XPNPEPL) homologous to X-prolyl aminopeptidase (aminopeptidase P)

A novel human cDNA (XPNPEPL) encoding a protein of 623 amino acids exhibiting 44% sequence identity and 62% sequence similarity to pig kidney X-prolyl aminopeptidase (aminopeptidase P; EC 3.4.11.9) was obtained by reverse transcription/polymerase chain reaction of phytohemagglutinin-stimulated lymphocyte mRNA. Conserved sequences were found with the prokaryotic X-prolyl aminopeptidase encoding gene (pepP). The human gene translation product exhibits a high sequence homology to the Schizosaccharomyces pombe chromosome I hypothetical protein C22G7.01c and to the S. cerevisiae ORF y11029w. Northern blot analysis indicates an ubiquitous expression of the human XPNPEPL sequence.

Immune markers in fibromyalgia: comparison with major depressed patients and normal volunteers

BACKGROUND

There is a high degree of comorbidity between fibromyalgia and major depression. The latter is characterized by signs of immune activation, whereas the immune status in fibromyalgia is not yet elucidated. The aims of the present study were to examine (i) neopterin and biopterin excretion in 24-h urine of patients with fibromyalgia compared with normal volunteers and patients with major depression; and (ii) the effects of subchronic treatment with sertraline (11 weeks) on the urinary excretion of neopterin and biopterin.

METHODS

Measurements of neopterin, biopterin, pseudouridine, creatinine and uric acid in 24-h urine were performed by means of HPLC in 14 fibromyalgia and ten major depressed patients and 17 normal volunteers.

RESULTS

There were no significant differences in urine excretion of the above five analytes between patients with fibromyalgia and normal volunteers. Patients with major depression showed significantly higher urinary neopterin excretion than normal volunteers and fibromyalgia patients. Patients with fibromyalgia and major depression had a significantly increased neopterin/creatinine ratio. Fibromyalgia patients had significantly lower urinary excretion of creatinine than patients with major depression. In fibromyalgia patients, there were no significant effects of sertraline treatment on any of the urine analytes.

CONCLUSIONS

The findings suggest that fibromyalgia, in contrast to major depression, may not be accompanied by activation of cell-mediated immunity.

LIMITATION

Other immune markers should be measured in fibromyalgia before drawing definite conclusions.

CLINICAL RELEVANCE

Increased urinary excretion of neopterin can be used as a marker for major depression, but not fibromyalgia.

Analysis of the CDKN2A, CDKN2B and CDK4 genes in 48 Australian melanoma kindreds

Germline mutations within the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene and one of its targets, the cyclin dependent kinase 4 (CDK4) gene, have been identified in a proportion of melanoma kindreds. In the case of CDK4, only one specific mutation, resulting in the substitution of a cysteine for an arginine at codon 24 (R24C), has been found to be associated with melanoma. We have previously reported the identification of germline CDKN2A mutations in 7/18 Australian melanoma kindreds and the absence of the R24C CDK4 mutation in 21 families lacking evidence of a CDKN2A mutation. The current study represents an expansion of these efforts and includes a total of 48 melanoma families from Australia. All of these families have now been screened for mutations within CDKN2A and CDK4, as well as for mutations within the CDKN2A homolog and 9p21 neighbor, the CDKN2B gene, and the alternative exon 1 (E1beta) of CDKN2A. Families lacking CDKN2A mutations, but positive for a polymorphism(s) within this gene, were further evaluated to determine if their disease was associated with transcriptional silencing of one CDKN2A allele. Overall, CDKN2A mutations were detected in 3/30 (10%) of the new kindreds. Two of these mutations have been observed previously: a 24 bp duplication at the 5' end of the gene and a G to C transversion in exon 2 resulting in an M531 substitution. A novel G to A transition in exon 2, resulting in a D108N substitution was also detected. Combined with our previous findings, we have now detected germline CDKN2A mutations in 10/48 (21%) of our melanoma kindreds. In none of the 'CDKN2A-negative' families was melanoma found to segregate with either an untranscribed CDKN2A allele, an R24C CDK4 mutation, a CDKN2B mutation, or an E1beta mutation. The last three observations suggest that these other cell cycle control genes (or alternative gene products) are either not involved at all, or to any great extent, in melanoma predisposition.

The oxazolidinone eperezolid binds to the 50S ribosomal subunit and competes with binding of chloramphenicol and lincomycin

The oxazolidinones are a novel class of antibiotics that act by inhibiting protein synthesis. It as been reported that the drug exerts its primary activity on the initiation phase of translation. In order to study the possibility of direct interaction between the drug and the ribosome, we have developed a binding assay using 14C-labelled eperezolid (PNU-100592; formerly U-100592). Eperezolid binds specifically to the 50S ribosomal subunit of Escherichia coli. The specific binding of eperezolid is dose dependent and is proportional to the ribosome concentrations. Scatchard analysis of the binding data reveals that the dissociation constant (Kd) is about 20 microM. The binding of eperezolid to the ribosome is competitively inhibited by chloramphenicol and lincomycin. However, unlike chloramphenicol and lincomycin, eperezolid does not inhibit the puromycin reaction, indicating that the oxazolidinones have no effect on peptidyl transferase. In addition, whereas lincomycin and, to some extent, chloramphenicol inhibit translation termination, eperezolid has no effect. Therefore, we conclude that the oxazolidinones inhibit protein synthesis by binding to the 50S ribosomal subunit at a site close to the site(s) to which chloramphenicol and lincomycin bind but that the oxazolidinones are mechanistically distinct from these two antibiotics.

Mechanism of action of oxazolidinones: effects of linezolid and eperezolid on translation reactions

The oxazolidinones are a new class of synthetic antibiotics with good activity against gram-positive pathogenic bacteria. Experiments with a susceptible Escherichia coli strain, UC6782, demonstrated that in vivo protein synthesis was inhibited by both eperezolid (formerly U-100592) and linezolid (formerly U-100766). Both linezolid and eperezolid were potent inhibitors of cell-free transcription-translation in E. coli, exhibiting 50% inhibitory concentrations (IC50s) of 1.8 and 2.5 microM, respectively. The ability to demonstrate inhibition of in vitro translation directed by phage MS2 RNA was greatly dependent upon the amount of RNA added to the assay. For eperezolid, 128 microg of RNA per ml produced an IC50 of 50 microM whereas a concentration of 32 microg/ml yielded an IC50 of 20 microM. Investigating lower RNA template concentrations in linezolid inhibition experiments revealed that 32 and 8 microg of MS2 phage RNA per ml produced IC50s of 24 and 15 microM, respectively. This phenomenon was shared by the translation initiation inhibitor kasugamycin but not by streptomycin. Neither oxazolidinone inhibited the formation of N-formylmethionyl-tRNA, elongation, or termination reactions of bacterial translation. The oxazolidinones appear to inhibit bacterial translation at the initiation phase of protein synthesis.

Deficiency of inflammatory cell adhesion molecules protects against atherosclerosis in mice

Leukocyte and endothelial cell adhesion molecules (CAMs) are essential for emigration of leukocytes, with the selectins mediating the initial step of leukocyte "rolling" and the beta 2-(CD18) integrins and intercellular adhesion molecule-1 (ICAM-1) being important for firm adhesion and emigration. On the basis of evidence for an inflammatory component in the pathogenesis of atherosclerosis, including increased expression of CAMs, cytokines, and growth factors, we tested the hypothesis that decreased expression of inflammatory CAMs would reduce susceptibility to atherosclerosis. Using C57BL/6 mice fed a high-fat diet, we observed a 50% to 75% reduction in atherosclerotic fatty streaks in mice with homozygous mutations for ICAM-1, P-selectin, CD18, both ICAM-1 and CD18, or both ICAM-1 and P-selectin. In contrast to previous evidence of increased expression of CAMs in atherosclerotic lesions, which does not prove a cause-and-effect relationship, these data indicate directly that the level of expression of CAMs can determine the susceptibility to the formation of atherosclerotic fatty streaks. The results suggest that genetic variation at these loci could influence susceptibility to atherosclerosis and that pharmacological reduction of the expression or function of these CAMs might protect against atherosclerosis.

RNA synthesis inhibitors alter the subnuclear distribution of DNA topoisomerase I

The acute effect of RNA and DNA synthesis inhibitors on DNA topoisomerase (topo) I localization within cells was examined. Indirect immunofluorescence revealed that topo I was distributed throughout the nuclei but was concentrated in nucleoli of untreated K562 leukemia cells and A549 non-small cell lung cancer cells. Treatment with the DNA polymerase inhibitor aphidicolin did not alter this distribution. In contrast, 30-60 min after addition of the RNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) at concentrations that inhibited [3H]uridine incorporation into RNA by > or = 50%, topo I was visible throughout the nuclei without nucleolar accentuation. Western blotting and activity assays confirmed that the amount of topo I polypeptide and topo I activity were unaltered by the brief DRB treatment. Within 30 min of DRB removal, topo I relocalized to the nucleoli in the absence or presence of the protein synthesis inhibitor cycloheximide. Collectively, these results suggest a reversible translocation of topo I out of the nucleoli when RNA synthesis is inhibited. Treatment with the topo I poisons topotecan or camptothecin, agents that also inhibit RNA synthesis, likewise caused redistribution of topo I to nonnucleolar regions of the nucleus in a variety of cell types. In DC3F hamster lung fibroblasts, 2.5 microM topotecan or 1.25 microM camptothecin was sufficient to cause this topo I redistribution. In DC3F/C-10 cells that contain a mutant camptothecin-resistant topo I, topo I relocalization required 50-fold higher concentrations of topotecan or camptothecin but not DRB. These observations not only suggest that accumulation of topo I in the nucleolus is related to ongoing RNA synthesis but also raise the possibility of screening for some types of camptothecin resistance at the single-cell level using a rapid immunofluorescence-based assay.

The effect of population density on the development of experimental atherosclerosis in female mice

The effect of cage population density on plasma lipids and the development of atherosclerosis was examined in female C57BL/6 mice. Mice were housed at a density of one, two or five animals per cage and fed an atherogenic diet for 28 weeks. Subsequently, the animals were bled, sacrificed, the hearts removed and the extent of fatty lesion development in the aorta examined and quantified. As the population density increased, there was a statistically significant increase in total cholesterol levels, VLDL+LDL cholesterol levels, the VLDL+LDL/HDL ratio and lesion severity. These differences are due to the psychosocial stress associated with living within a confined space with high population density over an extended period of time.

Designing zinc-finger ADR1 mutants with altered specificity of DNA binding to T in UAS1 sequences

Yeast ADR1 contains two Cys2,His2 zinc fingers needed for DNA binding to the upstream activation sequence UAS1, with bases T5T6G7-G8A9G10 in the ADH2 promoter. Potential DNA-contacting amino acid residues at -1, +3, and +6 in the alpha-helical domains of ADR1's fingers one and two include RHR-RLR; however, the latter finger two residues Leu146 and Arg149 had not proved to be crucial for ADR1 binding, even though Leu146-T6 and Arg149-T5 interactions with UAS1 DNA were predicted. We altered Leu146 or Arg149 by PCR cassette mutagenesis, to study ADR1 mutant binding to 16 UAS1 variants of thymine bases T5 and T6. Mutation of Leu146 to His, making finger two (RLR) like finger one (RHR), decreased binding to wild type UAS1 having T6, but enhanced its binding strength to sequences having purines G6 or A6, similar to binding seen between finger one's His118 and base A9 of UAS1. Mutating Leu146 to Lys caused this finger two RKR mutant to bind strongly to both G6 and T6, possibly by lysine's amine H-bonding to the carbonyl of guanine or thymine. Specificity of ADR1 for UAS1 with T6 may thus be due to hydrophobic interaction between Leu146 and the T6 methyl group. ADR1 mutants with either His or Lys in the central +3 residue (146) of zinc finger two, which have Arg149 in the +6 alpha-helical position, bind with UAS1 mutant sequences having G5 very strongly, T5 strongly, A5 intermediately, and C5 weakly.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular binding site and membrane binding proteins for triglyceride-rich lipoproteins in human monocyte-macrophages and THP-1 monocytic cells

Triglyceride- and cholesterol-rich foam cells derived from monocyte-macrophages are commonly associated with some forms of hypertriglyceridemia. In this report, direct binding studies at 4 degrees C demonstrate that human monocyte-macrophages (HMM) 1-6 days after isolation from blood and human THP-1 monocytic cells, before and up to 7 days after differentiation with phorbol ester, exhibit a high affinity (Kd 3-6 nM), saturable, specific, and apolipoprotein (apo) E-independent binding site for the uptake and degradation of certain triglyceride-rich lipoproteins (TGRLP). Ligand blotting analysis identified two membrane binding proteins (MBP) of apparent molecular weights of 200 and 235 kDa (MBP 200 and MBP 235) in both cell types that share the same ligand specificity as the cellular site and bind hypertriglyceridemic (HTG) VLDL, trypsinized VLDL devoid of apoE (tryp-VLDL), and dietary plasma chylomicrons from normal subjects but not LDL, acetyl LDL, or normal VLDL with high affinity. Neither lipoprotein lipase nor apoE are required for TGRLP binding to the cells or the isolated MBPs. The cellular binding site and the MBPs are expressed at similar levels at all stages of differentiation, unlike the LDL or the acetyl LDL receptor. TGRLP that bind to the MBPs induce rapid, saturable, cellular triglyceride accumulation in monocytes as well as macrophages; normal VLDL does not. In addition, the cellular high affinity binding site and MBP 200 and 235 are not affected by the media sterol content, unlike the LDL receptor. Taken together, these data indicate that human monocyte-macrophages exhibit a high affinity, saturable, specific, apoE- and lipoprotein lipase-independent binding site and membrane binding proteins for TGRLP that differ in expression, specificity, and molecular size from receptors of the LDL receptor gene family or the acetyl LDL receptor. The shared characteristics of the cellular binding site with MBP 200 and MBP 235 suggest that they are candidates for the receptor-mediated, apoE-independent uptake of HTG-VLDL and chylomicrons by monocytes and macrophages and therefore may be involved in foam cell formation.

Synthesis and biological evaluation of antiplatelet 2-aminochromones

The synthesis and biological evaluation of a series of antiplatelet 2-morpholinylchromones has been described. Modification of the C-7 phenylmethoxy group of 8-methyl-7-(phenylmethoxy)-2-(4-morpholinyl)-4H-1-benzopyran-4-one (2) has led to the discovery of a series of 7-[(amino-ethyl)oxy]-8-methyl derivatives which are potent inhibitors of ADP-induced platelet aggregation. Several members of this class proved active in preventing platelet-dependent thrombus formation in the dog, including 8-methyl-7-[2-(4-methyl-1-piperazinyl)ethoxy]-2-(4- morpholinyl)-4H-1-benzopyran-4-one (39) which was devoid of hemodynamic effects at the effective antithrombotic dose.

Severe atherosclerosis in transgenic mice expressing simian cholesteryl ester transfer protein

Cholesteryl ester transfer protein (CETP) is a plasma protein that mediates the exchange of neutral lipids among the lipoprotein. Because the principal core lipid of very-low-density lipoprotein (VLDL) is triglyceride and that of high-density lipoprotein (HDL) is cholesterol ester, CETP mediates a 'heteroexchange' of cholesterol ester for triglyceride between those lipoproteins. As a result, animals that express CETP tend to have higher VLDL and low-density lipoprotein (LDL) cholesterol levels, whereas those with no CETP activity tend to have high HDL cholesterol levels. Because VLDL and LDL are associated with the progression of atherosclerosis, and HDL are considered anti-atherogenic, CETP could be an 'atherogenic' protein, that is, given the other conditions required for atherosclerosis to develop, expression of CETP would accelerate the rate at which the arterial lesions progress. We report here that transgenic mice expressing CETP had much worse atherosclerosis than did non-expressing controls, and we suggest that the increase in lesion severity was due largely to CETP-induced alterations in the lipoprotein profile.

Zalcitabine compared with zidovudine in patients with advanced HIV-1 infection who received previous zidovudine therapy

OBJECTIVE

To evaluate the safety and efficacy of zalcitabine (also known as dideoxycytidine [ddC]) in patients with advanced human immunodeficiency virus (HIV) infection.

DESIGN

Open-label, randomized study.

SETTING

AIDS Clinical Trials Units, university-affiliated medical centers, and private practice groups.

PATIENTS

Patients with the acquired immunodeficiency syndrome (AIDS) or advanced AIDS-related complex who had tolerated zidovudine for 48 weeks or more.

INTERVENTION

Fifty-nine patients received zidovudine (500 to 1200 mg/d) and 52 patients received zalcitabine (2.25 mg/d).

MEASUREMENTS

The primary end points were survival and time to an AIDS-defining event or death.

RESULTS

Because significantly more patients withdrew from zidovudine therapy, the median duration of treatment was greater in the zalcitabine group than in the zidovudine group (279.0 days compared with 174.5 days; P = 0.001). The estimated 12-month, event-free probabilities were 53% for the zalcitabine group and 57% for the zidovudine group (relative risk, 1.02; 95% CI, 0.5 to 2.2). The estimated 12-month survival rates were 81% for the zalcitabine group and 75% for the zidovudine group (relative risk, 1.39; CI, 0.5 to 3.8). The rate of decline in CD4 lymphocyte counts was significantly slower in the zalcitabine group than in the zidovudine group (-0.08 cells/day compared with -0.17 cells/day). Patients in the zalcitabine group had gained an average of 0.5 kg at week 20 and 0.4 kg at week 24, whereas patients in the zidovudine group had lost an average of 1.8 kg at week 20 and 2.4 kg at week 24 (P = 0.04 and P = 0.05, respectively). Moderate to severe peripheral neuropathy and ulcerative stomatitis occurred in 10 and 9 patients, respectively, in the zalcitabine group.

CONCLUSIONS

The sample size for this study was smaller than planned, and no differences in survival and clinical end points were found. Slower rates of decline in CD4 lymphocyte counts and weight, however, were noted for the zalcitabine group.

2-Aminochromones block human platelet aggregation by inhibiting cyclic AMP-dependent phosphodiesterase leading to reduced platelet phospholipase C activity

We examined a series of 2-aminochromone analogs typified by U-84569 [8-methyl-2-(4-morpholinyl)-7-(1-naphthylenylmethoxy)-4H-1- benzopyran-4-one] as potential antithrombotic agents. U-84569 proved to be a potent inhibitor of human platelet aggregation regardless of the agonist used. Subsequent experiments showed that U-84569 increased platelet cyclic AMP (cAMP) levels in intact cells, but U-84569 did not directly stimulate adenylate cyclase. Our experiments showed that U-84569 was a potent inhibitor of the low Km cAMP-dependent phosphodiesterase with an IC50 of 300 nM in platelet cytosol. Isobutylmethylxanthine had an IC50 of 10 microM in the same system. Although U-84569 elevated cAMP by inhibiting cAMP metabolism, we were interested in the mechanism by which cAMP blocked aggregation. Our first experiments showed that U-84569 concentration-dependently blocked agonist-stimulated, but not phorbol myristate acetate-dependent, phosphorylation of the 47 kDa protein kinase C substrate in platelets. These data suggested that U-84569 could interrupt receptor-mediated signal transduction. In support of this hypothesis, U-84569 proved to be a potent inhibitor of thrombin-stimulated inositol phosphate synthesis, diacylglycerol formation and Ca++ mobilization in intact cells. These data indicate that agonist-stimulated phospholipase C activity was reduced in U-84569-treated cells. There was no direct influence of U-84569 on either basal or thrombin-stimulated phospholipase C activity in broken cells, suggesting that U-84569 (by inhibiting phosphodiesterase and elevating cAMP), indirectly blocked receptor-mediated phospholipase C activation and aggregation in platelets. The 2-aminochromones represent a new class of potent antithrombotic agents.