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Biochemical Pharmacology (v.75, #6)
In response to “Selective serotonin reuptake inhibitors—A new modality for the treatment of lymphoma/leukaemia?” by C. Schuster, et al. [Biochem. Pharmacol. 74 (9) 2007 1424–1435]
by John Gordon; Nicholas Barnes; Elisabeth Meredith; Mark Drayson (pp. e1-e3).
Ageing and atherosclerosis: Mechanisms and therapeutic options by Charis Costopoulos; Tze Vun Liew; Martin Bennett (pp. 1251-1261).
Atherosclerosis is the cause of most heart attacks and strokes, and is par excellence, a disease of ageing. Whilst disease prevalence and incidence increases with increasing decade of life, there is also evidence of accelerated cellular ageing in atherosclerosis. Such evidence includes impaired cell proliferation, early culture senescence and cell cycle markers of senescence in vitro and in vivo. Cell senescence is also characterised by loss of telomeres from the ends of chromosomes. Cellular ageing increases with disease severity, acting as a marker for disease, but also directly promotes atherosclerosis. Cellular ageing appears to be due to both abnormal proliferation of cells in an attempt to repair vessel damage, and a response to the damage itself. This review summarises the evidence of vascular cell senescence in atherosclerosis, the causes and consequences of accelerated cellular ageing in atherosclerosis, and identifies potential therapeutic options for both prevention and treatment.
Keywords: Abbreviations; 8-oxo-G; 8-oxo-guanine; A-T; ataxia telangiectasia; ATM; ataxia telangiectasia mutated (protein); ATR; ATM and Rad3-related (protein); DSBs; double-stranded (DNA) breaks; EC; endothelial cells; ECM; extracellular matrix; γ-H2AX; phosphorylated from of the histone protein H2AX; HMGCoA; 3-hydroxy-3-methylglutaryl coenzyme A; h-TERT; catalytic unit of the telomerase enzyme; ROS; reactive oxygen species; SIPS; stress-induced premature senescence; SAβG; senescence-associated β galactosidase; SSBs; single-stranded (DNA) breaks; VSMC; vascular smooth muscle cellAgeing; Atherosclerosis; Oxidative stress; Cell proliferation
Next generation topoisomerase I inhibitors: Rationale and biomarker strategies by Beverly A. Teicher (pp. 1262-1271).
Topoisomerase I (TopoI), an essential enzyme, produces a DNA single strand break allowing DNA relaxation for replication. The enzymatic mechanism involves sequential transesterifcations. The breakage and closure reactions generate phosphodiester bonds and similar free energies, so the reaction is freely reversible. The TopoI reaction intermediate consists of enzyme covalently linked to DNA dubbed a ‘cleavable complex’. Covalently bound TopoI–DNA complexes can be recovered. Camptothecin analogs, topotecan and irinotecan, are approved TopoI-targeted drugs. Both have limitations due to the equilibrium between the camptothecin lactone and ring-opened forms. Several strategies are being explored to develop improved TopoI inhibitors. Homocamptothecins, in which the metabolically labile camptothecin lactone is replaced with a more stable seven-membered β-hydroxylactone, are potent anticancer agents. Gimatecan is a seven-position modified lipophilic camptothecin developed to provide rapid uptake and accumulation in cells and a stable TopoI–DNA–drug ternary complex. Diflomotecan, a homocamptothecin, and gimatecan are in Phase II clinical trial. Among non-camptothecins, edotecarin, an indolocarbazole that results in DNA C/T-G cleavage compared with T-G/A for camptothecins, is in Phase II clinical trial. Indenoisoquinolines were identified as TopoI inhibitors by the NCI 60-cell line COMPARE analysis. Co-crystal structures of two indenoisoquinolines with TopoI–DNA elucidated the structure of the ternary complex. Indenoisoquinolines are in preclinical development. Dibenzonaphthyridinone TopoI inhibitors have undergone extensive structure–activity examination. ARC-111 was selected for in-depth preclinical study. Biomarkers are under investigation to predict clinical efficacy from preclinical models, to allow determination of drug targeting in vivo and to aid selection of patients most likely to benefit from TopoI inhibitor therapy. γ-H2AX formation may be a useful pharmacodynamic marker. A gene signature developed for topotecan sensitivity/resistance may have value in patient identification. Convergence of these efforts should result in clinically effective second generation TopoI inhibitors.
Keywords: Topoisomerase I; Homocamptothecin; Gimatecan; Indenoisoquinolines; Edotecarin; Pharmacodynamic markers
Quinolones as enhancers of camptothecin-induced cytotoxic and anti-topoisomerase I effects by Debby Reuveni; Drora Halperin; Itamar Shalit; Esther Priel; Ina Fabian (pp. 1272-1281).
Camptothecins (CPTs) are topoisomerase I (topo I) inhibitor chemotherapeutic agents. Studies indicate that combination therapy is needed in most therapeutic protocols with camptothecins. Certain fluoroquionolones inhibit topoisomerase II activity in eukaryotic cells. We showed previously that the fluoroquionolone moxifloxacin inhibited purified human topoisomerase II, acted synergistically with etoposide and enhanced anti-proliferative effect in THP-1 and Jurkat cells. There is no information on flouroquionolone's activity on topoisomerase I. We examined the effect of moxifloxacin and ciprofloxacin alone or in combination with camptothecin on purified topoisomerase I activity and further analysed their combined activity on proliferation and apoptosis in HT-29 cells. Moxifloxacin and ciprofloxacin alone slightly inhibited purified topoisomerase I activity; however in combination with camptothecin it led to a 82% and 64% reduction in enzyme activity, respectively. Moreovwer, our studies indicate that incubation of HT-29 cells with a combination of moxifloxacin or ciprofloxacin with CPT increases cellular topoisomerase I inhibitory activity. In cell proliferation assays, addition of moxifloxacin to 1nM camptothecin enhanced its cytotoxic activity by three-fold and was similar to that of 50nM camptothecin alone (45±2.1% inhibition). Ciprofloxacin enhanced cytotoxic activity to a lesser extent. Apoptosis studies showed up to 1.6-fold increase in annexin V positive cells when the fluoroquinolones were combined with camptothecin as compared to camptothecin alone. Analysis of the proangiogenic factors IL-8 and VEGF showed significant reduction in IL-8 production by moxifloxacin and ciprofloxacin up to 48% and in VEGF secretion from the cells. Further in vivo and clinical studies of camptothecins combined with the above fluoroquinolones are warranted.
Keywords: Topoisomerase I activity; Moxifloxacin; Ciprofloxacin; Cytotoxicity; Apoptosis; Angiogenic factors
Modulation of gold(III) porphyrin 1a-induced apoptosis by mitogen-activated protein kinase signaling pathways by Ying Wang; Qing-Yu He; Chi-Ming Che; Sai Wah Tsao; Raymond Wai-Yin Sun; Jen-Fu Chiu (pp. 1282-1291).
Gold(III) porphyrin 1a is a novel gold(III) complex with selective anticancer effect in a number of human carcinoma cell lines. We have previously shown that gold(III) porphyrin 1a mediated mitochondrial transmembrane potential (Δ Ψm) depletion, leading to cytochrome c release, nucleus translocation of apoptosis-inducing factor (AIF), and generation of reactive oxygen species (ROS). The current study addressed gold(III) porphyrin 1a-induced phosphoproteome alterations and modulation of cell death by the mitogen-activated protein kinase (MAPK) family proteins. ERK and p38MAPK were transiently activated upon gold(III) porphyrin 1a treatment. Inhibition of p38MAPK phosphorylation rescued gold(III) porphyrin 1a-induced cell death upstream of caspase activation. Attenuation of Δ Ψm was the primary effect of gold(III) porphyrin 1a leading to p38MAPK phosphorylation. Further functional proteomic study suggested that differential regulation of phosphotyrosine proteins were related to p38MAPK activation in gold(III) porphyrin 1a-induced signal transduction cascade. In summary, p38MAPK modulated gold(III) porphyrin 1a-induced cell death downstream of mitochondria, and phosphorylation of multiple proteins also involved in this process. These results suggested that gold(III) porphyrin 1a is a promising anticancer agent directed toward the mitochondria.
Keywords: Gold(III) compound; Mitochondria; MAPK; Apoptosis; Tyrosine phosphorylation; Proteomics
TGF-β1 increases motility and αvβ3 integrin up-regulation via PI3K, Akt and NF-κB-dependent pathway in human chondrosarcoma cells by Ying-Yi Yeh; Chung-Chieh Chiao; Wen-Yen Kuo; Yu-Chun Hsiao; Ying-Ju Chen; Ying-Ying Wei; Tzu-Hsu Lai; Yi-Chin Fong; Chih-Hsin Tang (pp. 1292-1301).
Transforming growth factor-β1 (TGF-β1) plays an essential role in tumor progression and metastasis. Integrins are the major adhesive molecules in mammalian cells. Here we found that TGF-β1 increased the migration and cell surface expression of αvβ3 integrin in human chondrosarcoma cells (JJ012 cells). Phosphatidylinositol 3-kinase inhibitor (PI3K; Ly294002) or Akt inhibitor inhibited the TGF-β1-induced increase the migration of chondrosarcoma cells. TGF-β1 stimulation increased the phosphorylation of p85 subunit of PI3K, and serine 473 of Akt. In addition, treatment of JJ102 cells with NF-κB inhibitor (PDTC) or IκB protease inhibitor (TPCK) inhibited TGF-β1-induced cells migration and integrins expression. Treatment of JJ012 cells with TGF-β1-induced IκB kinase α/β (IKKα/β) phosphorylation, IκBα phosphorylation, p65 Ser536 phosphorylation, and κB-luciferase activity. The TGF-β1-mediated increases in IKKα/β phosphorylation and p65 Ser536 phosphorylation were inhibited by Ly294002 and Akt inhibitor. Cotransfection with p85 and Akt mutants also reduced the TGF-β1-induced κB-luciferase activity. Taken together, these results suggest that the TGF-β1 acts through PI3K/Akt, which in turn activates IKKα/β and NF-κB, resulting in the activations of αvβ3 integrins and contributing the migration of chondrosarcoma cells.
Keywords: Abbreviations; TGF-β1; transforming growth factor-β1; PI3K; phosphatidylinositol 3-kinase; IKKα/β; IκB kinase α/β; ECM; extracellular matrix; SDF-1; stromal cells-derived factor-1; NF-κB; nuclear factor-κBTGF-β1; Chondrosarcoma; Integrin; Migration; NF-κB
Inhibition of P-glycoprotein (ABCB1)- and multidrug resistance-associated protein 1 (ABCC1)-mediated transport by the orally administered inhibitor, CBT-1® by Robert W. Robey; Suneet Shukla; Elizabeth M. Finley; Robert K. Oldham; Daryl Barnett; Suresh V. Ambudkar; Tito Fojo; Susan E. Bates (pp. 1302-1312).
Cellular expression of ATP-binding cassette (ABC) transport proteins, such as P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP1), or ABCG2, is known to confer a drug-resistant phenotype. Thus, the development of effective transporter inhibitors could be of value to cancer treatment. CBT-1® is a bisbenzylisoquinoline plant alkyloid currently in development as a Pgp inhibitor. We characterized its interactions with the three major ABC transporters associated with drug resistance – Pgp, MRP1 and ABCG2 – and compared it to other known inhibitors. CBT-1® completely inhibited rhodamine 123 transport from Pgp-overexpressing cells at a concentration of 1μM. Additionally, 1μM completely reversed Pgp-mediated resistance to vinblastine, paclitaxel and depsipeptide in SW620 Ad20 cells. CBT-1® was found to compete [125I]-IAAP labeling of Pgp with an IC50 of 0.14μM, and low concentrations of CBT-1® (<1μM) stimulated Pgp-mediated ATP hydrolysis. In MRP1-overexpressing cells, 10μM CBT-1® was found to completely inhibit MRP1-mediated calcein transport. CBT-1® at 25μM did not have a significant effect on ABCG2-mediated pheophorbide a transport. Serum levels of CBT-1® in samples obtained from eight patients receiving CBT-1® increased intracellular rhodamine 123 levels in CD56+ cells 2.1- to 5.7-fold in an ex vivo assay. CBT-1® is able to inhibit the ABC transporters Pgp and MRP1, making it an attractive candidate for clinical trials in cancers where Pgp and/or MRP1 might be overexpressed. Further clinical studies with CBT-1® are warranted.
Keywords: P-glycoprotein; MRP1; ABCG2; CBT-1; ®; Drug resistance; Inhibitor
Increased mitochondrial DNA copy-number in CEM cells resistant to delayed toxicity of 2′,3′-dideoxycytidine by Mia Bjerke; Maribel Franco; Magnus Johansson; Jan Balzarini; Anna Karlsson (pp. 1313-1321).
The nucleoside analog 2′,3′-dideoxycytidine (ddC) has been used for treatment of human immunodeficiency virus (HIV) infections. ddC causes delayed toxicity when cells are exposed to the drug at low concentration for prolonged periods of time. The delayed toxicity is due to inhibition of mitochondrial DNA (mtDNA) replication, which results in mtDNA depletion and mitochondrial dysfunction. In the present study we have cultured CEM T-lymphoblast cells in the presence of low concentrations of ddC to generate two cell lines resistant to the delayed toxicity of the drug. Both cell lines were resistant to mtDNA depletion by ddC. The mechanism of ddC resistance was investigated and we showed that the resistant cells had decreased mRNA expression of the nucleoside kinases deoxycytidine kinase and thymidine kinase 2. We also studied the mitochondrial DNA in the cells and showed that the ddC-resistant cells had structurally intact mtDNA but 1.5–2-fold increased mtDNA copy-number as well as increased levels of the mitochondrial transcription factor A (Tfam). Our study suggests that cells may increase their level of mtDNA to counteract mtDNA depletion induced by ddC, while keeping pronounced antiviral activity of the drug.
Keywords: Abbreviations; ddC; 2′,3′-dideoxycytidine; ddCTP; 2′,3′-dideoxycytidine 5′-triphosphate; dCK; dexoycytidine kinase [EC 2.7.1.74]; TK1; thymidine kinase 1 [EC 2.7.1.21]; TK2; thymidine kinase 2 [EC 2.7.1.21]; HIV; human immunodeficiency virus; mtDNA; mitochondrial DNA; RT-PCR; reverse transcriptase polymerase chain reaction; NDPK; nucleoside diphosphate kinase [EC 2.7.4.6]; Tfam; mitochondrial transcription factor A; EtBr; ethidium bromideNucleoside analogs; Drug resistance; Retroviral therapy; Mitochondrial DNA; Human immunodeficiency virus
Effects of V2-receptor antagonist tolvaptan and the loop diuretic furosemide in rats with heart failure by Punniyakoti T. Veeraveedu; Kenichi Watanabe; Meilei Ma; Suresh S. Palaniyandi; Ken’ichi Yamaguchi; Makoto Kodama; Yoshifusa Aizawa (pp. 1322-1330).
Diuretics are frequently required to treat fluid retention in patients with chronic heart failure (CHF). Unfortunately, they can lead to a decline in renal function, electrolyte depletion, and neurohormonal activation. Arginine vasopressin (AVP) promotes renal water reabsorption via the V2 receptor (V2R) and its levels are increased in CHF. This study was conducted to characterize the diuretic effect of tolvaptan, a non-peptide AVP V2R antagonist, and furosemide, a loop diuretic in a rat model of CHF after experimental autoimmune myocarditis. CHF was elicited in Lewis rats by immunization with porcine cardiac myosin, and 28 days after immunization rats were treated for 28 days with oral tolvaptan, and furosemide. CHF was characterized by left ventricular remodeling and impaired systolic and diastolic function. Tolvaptan produces a diuresis comparable to furosemide. Unlike tolvaptan, furosemide significantly increased urinary sodium and potassium excretion. Tolvaptan markedly elevated electrolyte-free water clearance (E-CH2O) or aquaresis to a positive value and increased urinary AVP excretion. In contrast to tolvaptan, furosemide elevated only electrolyte clearance (E-Cosm) but not E-CH2O. The differences in diuretic profile reflected the changes in plasma sodium and hormone levels. Tolvaptan dose dependently elevated plasma sodium concentration, but furosemide tended to decrease it. Furosemide significantly elevated plasma renin activity and aldosterone concentration. On the other hand, tolvaptan did not affect these parameters. Our results suggest that, tolvaptan have a potential medical benefit for the treatment of edematous conditions in CHF by removing excess water from the body without activating the RAAS or causing serum electrolyte imbalances.
Keywords: Chronic heart failure; V; 2; -receptor antagonism; Aquaretics; Vasopressin; Hyponatremia
JM91, a newly synthesized indoledione derivative, inhibits rat aortic vascular smooth muscle cells proliferation and cell cycle progression through inhibition of ERK1/2 and Akt activations by Ji-Min Seo; Yong-Ri Jin; Chung-Kyu Ryu; Tack-Joong Kim; Xiang-Hua Han; Jin-Tae Hong; Hwan-Soo Yoo; Chong-Kil Lee; Yeo-Pyo Yun (pp. 1331-1340).
The increased potential for growth of vascular smooth muscle cells (VSMCs) is a key abnormality in the development of atherosclerosis and postangioplasty restenosis. Platelet-derived growth factor (PDGF)-BB is a potent mitogen for VSMCs that plays an important role in the intimal accumulation of VSMCs. This study examined the effect of JM91, a newly synthesized indoledione derivative, on the proliferation of PDGF-BB-stimulated rat aortic VSMCs. The antiproliferative effect of JM91 on rat aortic VSMCs was examined by cell counting and [3H]thymidine incorporation assay. The pre-incubation of JM91 (0.5–3.0μM) significantly inhibited the proliferation and DNA synthesis of 25ng/mL PDGF-BB-stimulated rat aortic VSMCs in a concentration-dependent manner. JM91 inhibited the PDGF-BB-stimulated phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt kinase, while had no effect on PLCγ1 and PDGF-Rβ activation. In addition, treatment with JM91 (0.5–3.0μM) induced cell-cycle arrest in the G1 phase, which was associated with the down–regulation of cyclins and CDKs. These findings suggest that the inhibitory effects of JM91 against proliferation, DNA synthesis and cell cycle progression of PDGF-BB-stimulated rat aortic VSMCs are mediated by the suppression of the ERK1/2 and PI3K/Akt signaling pathways. Furthermore, JM91 may be a potential antiproliferative agent for the treatment of atherosclerosis and angioplasty restenosis.
Keywords: Indoledione; Vascular smooth muscle cell; Platelet-derived growth factor; Phosphatidylinositol 3-kinase; Extracellular signal-regulated kinase
Caged agonist of P2Y1 and P2Y12 receptors for light-directed facilitation of platelet aggregation by Zhan-Guo Gao; Béatrice Hechler; Pedro Besada; Christian Gachet; Kenneth A. Jacobson (pp. 1341-1347).
We have prepared a caged form (MRS2703) of a potent dual agonist of the P2Y1 and P2Y12 nucleotide receptors, 2-MeSADP, by blocking the β-phosphate group with a 1-(3,4-dimethyloxyphenyl)eth-1-yl phosphoester. Although MRS2703 is itself inactive at human P2Y1 and P2Y12 receptors expressed heterologously in 1321N1 astrocytoma cells or in washed human platelets, this derivative readily regenerates the parent agonist upon mild irradiation with long-wave UV light (360nm). The functional effect of the regenerated agonist was demonstrated by a rise in intracellular calcium mediated by either P2Y1 or P2Y12 receptors in transfected cells. Washed human platelets exposed to a solution of MRS2703 were induced to aggregate upon UV irradiation. At 1.0μM MRS2703, full aggregation was achieved within 1min of irradiation. Thus, this caged nucleotide promises to be a useful probe for potent P2Y receptor activation with light-directed spatial and temporal control.
Keywords: Abbreviations; FBS; fetal bovine serum; MRS2500; (1′; R; ,2′; S; ,4′; S; ,5′; S; )-4-(2-iodo-6-methylamino-purin-9-yl)-1-[(phosphato)-methyl]-2-(phosphato)-bicyclo[3.1.0]hexane; MRS2703; P; 1; -2-(methylthio)adenosyl-P; 2; -(; RS; )-1-(4,5-dimethoxy-2-nitrophenyl)ethyl pyrophosphate, triethylammonium salt; 2-MeSADP; 2-methylthioadenosine 5′-diphosphate; DMEM; Dulbecco's modified Eagle's mediumAggregation; Nucleotides; G-protein-coupled receptors; Phospholipase C; Calcium
Topical transduction of superoxide dismutase mediated by HIV-1 Tat protein transduction domain ameliorates 12- O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice by Ha Yong Song; Ji Ae Lee; Sung Mi Ju; Ki-Yeon Yoo; Moo Ho Won; Hyung-Joo Kwon; Won Sik Eum; Sang Ho Jang; Soo Young Choi; Jinseu Park (pp. 1348-1357).
A domain (RKKRRQRRR) derived from HIV-1 Tat is one of the most efficient protein transduction domains (PTD) for delivering macromolecules including proteins into cells and tissues. Antioxidant enzymes such as superoxide dismutase (SOD) and catalase are major cellular defenses against oxidative stress which results in various diseases including skin inflammation. In this study, we examined the effect of SOD fused with HIV-1 Tat PTD (Tat-SOD) on TPA-induced skin inflammation in mice. Topical application of Tat-SOD to mice ears 1h after TPA application once a day for 3 days dose-dependently inhibited TPA-induced ear edema in mice. Topical application on mice ears of Tat-SOD also suppressed TPA-induced expression of proinflammatory cytokines such as TNF-α, IL-1β, and IL-6 as well as cyclooxygenase-2 (COX-2) and production of PGE2. Furthermore, topical application of Tat-SOD resulted in significant reduction in activation of NF-κB and mitogen-activated protein kinases (MAPK) in the mice ears treated with TPA. These data demonstrates that Tat-SOD inhibits TPA-induced inflammation in mice by reducing the levels of expression of proinflammatory cytokines and enzymes regulated by the NF-kappaB and MAPK and can be used as a therapeutic agent against skin inflammation related to oxidative damage.
Keywords: Abbreviations; SOD; superoxide dismutase; PTD; protein transduction domain; TPA; 12-; O; -tetradecanoylphorbol-13-acetate; ROS; reactive oxygen species; MAPK; mitogen-activated protein kinaseSOD; TPA; Inflammation; ROS; NF-κB
Release of arachidonic acid induced by tumor necrosis factor-α in the presence of caspase inhibition: Evidence for a cytosolic phospholipase A2α-independent pathway by Masaya Shimizu; Yuka Matsumoto; Takeshi Kurosawa; Chihiro Azuma; Masato Enomoto; Hiroyuki Nakamura; Tetsuya Hirabayashi; Masayuki Kaneko; Yasunobu Okuma; Toshihiko Murayama (pp. 1358-1369).
Stimulation of L929 cells with tumor necrosis factor-α (TNFα) caused cell death accompanied by a release of arachidonic acid (AA). Although the inhibition of caspases has been shown to cause necrosis in TNFα-treated L929 cells, its role in the TNFα-induced release of AA has not been elucidated. The release of AA is tightly regulated by phospholipase A2 (PLA2). To find out the mechanisms underlying the TNFα-induced release of AA, we investigated the relationship between TNFα stimulation and PLA2 regulation with and without zVAD, an inhibitor of caspases. In the present study, we found that treatment with TNFα and zVAD stimulated release of AA and cell death in C12 cells (a variant of L929 cells lacking α type of cytosolic PLA2 (cPLA2α)). Stimulation with TNFα/zVAD also caused the release of AA from L929-cPLA2α-siRNA cells. Treatment with pyrrophenone (a selective inhibitor of cPLA2α) completely inhibited the TNFα-induced release of AA, but only partially inhibited the TNFα/zVAD-induced response in L929 cells. The TNFα/zVAD-induced release of AA from C12 and L929-cPLA2α-siRNA cells was pyrrophenone-insensitive, but inhibited by treatment with butylated hydroxyanisole (BHA, an antioxidant). Treatment with dithiothreitol, which inactivates secretory PLA2 activity, decreased the amount of AA released by TNFα/zVAD. TNFα/zVAD appears to stimulate release of AA from C12 cells in a cPLA2α-independent, BHA-sensitive manner. The possible roles of secretory PLA2 and reactive oxygen species from different pools in the release of AA and cell death were discussed.
Keywords: cPLA; 2; α; Secretory PLA; 2; TNFα; Caspase; Reactive oxygen species
Differential effects of phorbol-13-monoesters on human immunodeficiency virus reactivation by Nieves Márquez; Marco A. Calzado; Gonzalo Sánchez-Duffhues; Moisés Pérez; Alberto Minassi; Alberto Pagani; Giovanni Appendino; Laura Diaz; Maria Ángeles Muñoz-Fernández; Eduardo Muñoz (pp. 1370-1380).
The persistence of latent reservoirs of HIV-1 represents a major barrier to virus eradication in patients treated with antiretrovirals. Prostratin is a non-tumor promoting 12-deoxyphorbol monoester capable of up-regulating viral expression from latent provirus and therefore is potentially useful for HIV adjuvant therapy and similar properties might be elicited by related non-tumor promoting phorboids. We have therefore investigated a series of phorbol 13-monoesters for their capacity to reactivate HIV latency. Using a Jurkat T cell line containing latent HIV proviruses, we found that prostratin and phorbol-13-stearate effectively activate HIV-1 gene expression in these latently infected cells, with phorbol-13-stearate being at least 10-fold more potent than prostratin, and its activity rapidly decreasing with a shortening of the acyl side chain. We further demonstrated that phorbol-13-stearate and prostratin stimulate IKK-dependent phosphorylation and degradation of IκBα, leading to activation of NF-κB. Moreover, prostratin, phorbol-13-hexanoate and phorbol-13-stearate also activate the JNK and ERK pathways. Studies with isoform-specific PKC inhibitors suggest that the classical PKCs play a prominent role in the responses elicited by phorbol-13-stearate. Nevertheless, this compound induces a translocation pattern of the PKC isotypes α and δ to cellular compartments distinctly different from that elicited by prostratin and PMA.
Keywords: Abbreviations; AP-1; activator protein-1; ERK; extracellular regulated kinase; HIV-LTR; HIV long terminal repeats; IκB; κB inhibitor; JNK; c-Jun N-terminal kinase; PKC; protein kinase C; NF-κB; nuclear factor; kappa; B; PMA; phorbol 12-myristate 13-acetate; P-13S; phorbol-13-stearate; TNFα; tumor necrosis factor-αHIV-1; Latency; Phorbol ester; Prostratin; PKC; NF-κB
Deoxyelephantopin inhibits cancer cell proliferation and functions as a selective partial agonist against PPARγ by Gang Zou; Zhenting Gao; Jidong Wang; Yu Zhang; Hong Ding; Jin Huang; Lili Chen; Yuewei Guo; Hualiang Jiang; Xu Shen (pp. 1381-1392).
Deoxyelephantopin (ESD) was reported to potentiate apoptosis, inhibit invasion and abolish osteoclastogenesis but no target protein was disclosed. Here, we discovered that ESD could significantly inhibit the proliferation of different cancer cells and induce apoptosis and cell cycle arrest at G2/M phase in HeLa cell. Moreover, biochemical and biophysical assays revealed that ESD acted as a specific partial agonist against PPARγ. Molecular docking with site-directed mutagenesis analyses indicated that ESD functioned as a partial agonist of PPARγ by adopting a distinct binding mode to PPARγ compared with rosiglitazone. The PPARγ knockdown results indicated that the inhibition of ESD against the cancer cell proliferation is more possibly through PPARγ-independent pathway and our findings might supply potent binding features for ESD/PPARγ interaction at atomic level, and shed light on the potential acting target information for this natural compound.
Keywords: Abbreviations; ESD; deoxyelephantopin; PPARγ; peroxisome proliferator-activated receptor-γ; TZDs; thiazolidinediones; NF-κB; nuclear factor-κB; LBD; ligand-binding domain; AF-2; ligand-dependent activation domain; SRC-1; steroid receptor coactivator-1; CBP; cAMP-response element-binding protein (CREB)-binding protein; IPTG; isopropyl-β-; d; -thiogalactoside; IKK; IκBα kinase; AP-1; activator protein-1; STAT; signal transduction and activator of transcription; HDAC3; (NCoR)-histone deacetylase-3Deoxyelephantopin; PPARγ; Partial agonist; Surface plasmon resonance; Molecular docking
Cyanidin 3-glucoside protects 3T3-L1 adipocytes against H2O2- or TNF-α-induced insulin resistance by inhibiting c-Jun NH2-terminal kinase activation by Honghui Guo; Wenhua Ling; Qing Wang; Chi Liu; Yan Hu; Min Xia (pp. 1393-1401).
Anthocyanins are naturally occurring plant pigments and exhibit an array of pharmacological properties. Our previous study showed that black rice pigment extract rich in anthocyanin prevents and ameliorates high-fructose-induced insulin resistance in rats. In present study, cyanidin 3-glucoside (Cy-3-G), a typical anthocyanin most abundant in black rice was used to examine its protective effect on insulin sensitivity in 3T3-L1 adipocytes exposed to H2O2 (generated by adding glucose oxidase to the medium) or tumor necrosis factor α (TNF-α). Twelve-hour exposure of 3T3-L1 adipocytes to H2O2 or TNF-α resulted in the increase of c-Jun NH2-terminal kinase (JNK) activation and insulin receptor substrate 1 (IRS1) serine 307 phosphorylation, concomitantly with the decrease in insulin-stimulated IRS1 tyrosine phosphorylation and cellular glucose uptake. Blocking JNK expression using RNA interference efficiently prevented the H2O2- or TNF-α-induced defects in insulin action. Pretreatment of cells with Cy-3-G reduced the intracellular production of reactive oxygen species, the activation of JNK, and attenuated H2O2- or TNF-α-induced insulin resistance in a dose-dependent manner. In parallel, N-acetyl-cysteine, an antioxidant compound, did not exhibit an attenuation of TNF-α-induced insulin resistance. Taken together, these results indicated that Cy-3-G exerts a protective role against H2O2- or TNF-α-induced insulin resistance in 3T3-L1 adipocytes by inhibiting the JNK signal pathway.
Keywords: Abbreviations; 2-DG; 2-deoxy-; d; -glucose; Cy-3-G; cyanidin 3-glucoside; DCF-DA; dihydrodichlorofluorescein diacetate; DMEM; Dulbecco's modified Eagle's medium; FBS; fetal bovine serum; GLUT4; glucose transporter 4; IRS1; insulin receptor substrate 1; JNK; c-Jun NH; 2; -terminal kinase; KRP; Krebs-Ringer's phosphate; MTT; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; NAC; N; -acetyl-cysteine; PM; plasma membrane; PY; phosphotyrosine; ROS; reactive oxygen species; siRNA; small interfering RNA; TNF-α; tumor necrosis factor α; TNFR1; TNF type-1 receptor; TRAF2; TNFR-associated factor 2Anthocyanin; Cyanidin 3-glucoside; c-Jun NH; 2; -terminal kinase; Insulin resistance; 3T3-L1 adipocyte
Acetaminophen normalizes glucose homeostasis in mouse models for diabetes by Howard G. Shertzer; Scott N. Schneider; Eric L. Kendig; Deborah J. Clegg; David A. D’Alessio; Mary Beth Genter (pp. 1402-1410).
Loss of pancreatic beta cell insulin secretion is the most important element in the progression of type 1 and type 2 diabetes. Since oxidative stress is involved in the progressive loss of beta cell function, we evaluated the potential for the over-the-counter analgesic drug and antioxidant, acetaminophen (APAP), to intervene in the diabetogenic process. We used mouse models for type 1 diabetes (streptozotocin) and type 2 diabetes (high-fat diet) to examine the ability of APAP to intervene in the progression of diabetes. In C57BL/6J mice, streptozotocin caused a dosage dependent increase in fasting blood glucose (FBG), from 100 to >600mg/dl. Daily APAP (20mg/kg BW, gastric gavage), significantly prevented and partially reversed the increase in FBG levels produced by streptozotocin. After 10 weeks on a high-fat diet, mice developed fasting hyperinsulemia and impaired glucose tolerance compared to animals fed a control diet. APAP largely prevented these changes in insulin and glucose tolerance. Furthermore, APAP prevented most of the increase in body fat in mice fed the high-fat diet. One protective mechanism for APAP is suggested by studies using isolated liver mitochondria, where low micromolar concentrations abolished the production of reactive oxygen that might otherwise contribute to the destruction of pancreatic β-cells. These findings suggest that administration of APAP to mice, in a dosage used safely by humans, reduces the production of mitochondrial reactive oxygen and concomitantly prevents the development of type 1 and type 2 diabetes in established animal models.
Keywords: Abbreviations; APAP; acetaminophen (; N; -(4-hydroxyphenyl)acetamide); FBG; fasting blood glucose; STZ; streptozotocin (1-methyl-1-nitroso-3-[2,4,5-trihydroxy-6-(hydroxymethyl)oxan-3-yl]-urea); T1DM; type 1 diabetes mellitus; T2DM; type 2 diabetes mellitusAcetaminophen; Glucose control; Insulin resistance; Oxidative stress; Type 1 and type 2 diabetes
Lobeline effects on tonic and methamphetamine-induced dopamine release by Clare J. Wilhelm; Robert A. Johnson; Amy J. Eshleman; Aaron Janowsky (pp. 1411-1415).
The mechanisms of interaction between lobeline and the dopamine transporter (DAT) or the vesicular monoamine transporter (VMAT-2) are not clear. The goal of this study was to elucidate the effects of lobeline on these transporters in a cell system co-expressing the DAT and VMAT-2. Lobeline caused release of [3H]dopamine to a similar extent as reserpine (VMAT-2 inhibitor), but was less efficacious than methamphetamine or dopamine. Additionally, lobeline decreased the [3H]dopamine-releasing effects of methamphetamine, unlike reserpine which increased release by methamphetamine. These results suggest that lobeline has unique properties at the DAT and VMAT-2 which may make it useful as a pharmacotherapeutic to treat methamphetamine abuse.
Keywords: Methamphetamine; Lobeline; Dopamine; Vesicular monoamine transporter; Dopamine transporter
Structure–activity relationship of coumarin derivatives on xanthine oxidase-inhibiting and free radical-scavenging activities by Hsiu-Chen Lin; Shin-Hui Tsai; Chien-Shu Chen; Yuan-Ching Chang; Chi-Ming Lee; Zhi-Yang Lai; Chun-Mao Lin (pp. 1416-1425).
We employed 1,1-diphenyl-2-picrylhydrazyl hydrate (DPPH)– and 5,5-dimethyl-1-pyrroline- N-oxide (DMPO)–electron spin resonance (ESR) to study the effects of suppression of reactive oxygen species (ROS) by eight selected coumarin derivatives under oxidative conditions. Esculetin was the most potent radical scavenger among the eight tested compounds. Our results suggest that the number of hydroxyl groups on the ring structure of coumarins is correlated with the effects of ROS suppression. We also investigated the effect of the derivatives on the inhibition of xanthine oxidase (XO) activity, and the structure–activity relationships (SARs) of these derivatives against XO activity were further examined using computer-aided molecular modeling. All determined derivatives competitively inhibited XO. The results of the structure-based molecular modeling exhibited interactions between coumarins and the molybdopterin region of XO. The carbonyl pointed toward the Arg880, and the ester O atom formed hydrogen bonds with Thr1010. Esculetin, which bears two hydroxyl moieties on its benzene rings, had the highest affinity toward the binding site of XO, and this was mainly due to the interaction of 6-hydroxyl with the E802 residue of XO. The hypoxanthine/XO reaction in the DMPO-ESR technique was used to assess the combined effect on enzyme inhibition and ROS suppression by these coumarins, and the results showed that esculetin was the most potent agent among the tested compounds. We further evaluated the effects of the test compounds on living cells, and esculetin was still the most potent agent at protecting cells against ROS-mediated Aβ-damage among the tested coumarins.
Keywords: Coumarin; Esculetin; Molecular modeling; ROS; Xanthine oxidase
Flavonoids diosmetin and luteolin inhibit midazolam metabolism by human liver microsomes and recombinant CYP 3A4 and CYP3A5 enzymes by Luigi Quintieri; Pietro Palatini; Alberto Nassi; Paolo Ruzza; Maura Floreani (pp. 1426-1437).
We evaluated the effects of increasing concentrations of the flavonoids salvigenin, diosmetin and luteolin on the in vitro metabolism of midazolam (MDZ), a probe substrate for cytochrome P450 (CYP) 3A enzymes, which is converted into 1′-hydroxy-midazolam (1′-OH-MDZ) and 4-hydroxy-midazolam (4-OH-MDZ) by human liver microsomes. Salvigenin had only a modest effect on MDZ metabolism, whereas diosmetin and luteolin inhibited in a concentration-dependent manner the formation of both 1′-OH-MDZ and 4-OH-MDZ, with apparent K i values in the 30–50μmol range. Both diosmetin and luteolin decreased 1′-OH-MDZ formation by human recombinant CYP3A4, but not CYP3A5, whereas they decreased 4-OH-MDZ formation by both recombinant enzymes. To assess whether any relationship exists between the physico-chemical characteristics of flavones and their effects on MDZ metabolism, we tested the effects of three other flavones (flavone, tangeretin, chrysin) on MDZ metabolism by human liver microsomes. Whereas flavones possessing more than two hydroxyl groups (luteolin, diosmetin) inhibited MDZ biotransformation, flavones lacking hydroxyl groups in their A and B rings (flavone, tangeretin) stimulated MDZ metabolism. We also found close relationships between the maximum stimulatory or inhibitory effects of flavones on 1′-OH-MDZ and 4-OH-MDZ formation rates and their log of octanol/water partition coefficients (log P) or their total number of hydroxyl groups. The results of the study may be of clinical relevance since they suggest that luteolin and diosmetin may cause pharmacokinetic interactions with co-administered drugs metabolized via CYP3A.
Keywords: Flavones; Midazolam; Human liver microsomes; CYP3A enzymes; Flavonoid–drug interaction
Corrigendum to “Synthesis of microtubule-interfering halogenated noscapine analogs that perturb mitosis in cancer cells followed by cell death” [Biochem. Pharmacol. 72 (4) (2006) 415–426]
by Ritu Aneja; Surya N. Vangapandu; Manu Lopus; Vijaya G. Viswesarappa; Neerupma Dhiman; Akhilesh Verma; Ramesh Chandra; Dulal Panda; Harish C. Joshi (pp. 1439-1440).