Check out our New Publishers' Select for Free Articles

Biochemical Pharmacology (v.82, #5)

Editorial Advisory Board (pp. iii).

Autophagy as a mediator of chemotherapy-induced cell death in cancer by Annick Notte; Lionel Leclere; Carine Michiels (pp. 427-434).

Since the 1940s, chemotherapy has been the treatment of choice for metastatic disease. Chemotherapeutic agents target proliferating cells, inducing cell death. For most of the history of chemotherapy, apoptosis was thought to be the only mechanism of drug-induced cell death. More recently, a second type of cell death pathway has emerged: autophagy, also called type II programmed cell death. Autophagy is a tightly regulated process by which selected components of a cell are degraded. It primarily functions as a cell survival adaptive mechanism during stress conditions. However, persistent stress can also promote extensive autophagy, leading to cell death, hence its name. Alterations in the autophagy pathway have been described in cancer cells that suggest a tumor-suppressive function in early tumorigenesis, but a tumor-promoting function in established tumors. Moreover, accumulating data indicate a role for autophagy in chemotherapy-induced cancer cell death. Here, we discuss some of the evidence showing autophagy-dependent cell death induced by anti-neoplastic agents in different cancer models. On the other hand, in some other examples, autophagy dampens treatment efficacy, hence providing a therapeutic target to enhance cancer cell killing. In this paper, we propose a putative mechanism that could reconcile these two opposite observations.

Keywords: Abbreviations; AMPK; AMP-dependent kinase; Atg; autophagy-related gene; DAMP; damage-associated molecular pattern molecules; DAPK1; death-associated protein kinase 1; ER; endoplasmic reticulum; HDAC; histone deacetylase; HIF; -1hypoxia-inducible factor-1; HMGB1; high-mobility group box 1; mTOR; mammalian target of rapamycin; PTEN; phosphatase and tensin homolog; RAGE; receptor for advanced glycation endproducts; ROS; reactive oxygen species; TSC2; tuberous sclerosis protein 2; ULK; Unc-151-like kinase; UVRAG; ultraviolet radiation resistance associated geneChemotherapy; Autophagy; Apoptosis; Cancer

Checks and balances: Interplay of RTKs and PTPs in cancer progression by Sarita K. Sastry; Lisa A. Elferink (pp. 435-440).

(A) Prolonged treatment with RTK inhibitors leads to acquired resistance. (B) Gain- or (C) loss-of-function of PTPs may contribute to resistance by activating RTK-independent pathways to promote cancer progression.In recent years, targeted therapies for receptor tyrosine kinases (RTKs) have shown initial promise in the clinical setting for the treatment of several tumors driven by these oncogenic signaling pathways. Unfortunately, clinical relapse due to acquired resistance to these molecular therapeutics is common. An improved understanding of how tumors bypass the inhibitory effects of RTK-targeted therapies has revealed a rich myriad of possible mechanisms for acquired resistance. Protein tyrosine phosphatases (PTPs) can function as oncogenes or tumor suppressors to either enhance or suppress RTK signaling. Recent studies suggest that the loss or gain of function of PTP's can significantly impinge on RTK signaling during tumor progression. Here we review the interplay between RTKs and PTPs as an emerging mechanism for acquired resistance to RTK-targeted therapies, that may aid in the design of improved therapies to prevent and overcome resistance in treatments for cancer patients.

Keywords: Abbreviations; Cag A; cytotoxin associated antigen A; DUSP; dual specificity phosphatase; EGF; epidermal growth factor; EGFR; EGF receptor; ErbBs; epidermal growth factor receptor family of receptor tyrosine kinases; FAK; focal adhesion kinase; FGFR; fibroblast growth factor receptor; HGF; hepatocyte growth factor; IGF-1R; type 1 insulin-like growth factor receptor; MEF; mouse embryonic fibroblast; Met; HGF receptor; PI3K; phosphatidylinositol 3-kinase; PIP2; phosphatidylinositol 4,5,-bisphosphate; PIP3; 3,4,5,-triphosphate; PTEN; phosphatase and tensin homolog deleted on chromosome 10; PTP; protein tyrosine phosphatases; NSCLC; non-small cell lung carcinoma; PDGF; platelet derived growth factor; PDGFR; PDGF receptor; RTK; receptor tyrosine kinase; SH2; src homology 2; shRNA; small hairpin RNA; SNP; single nucleotide polymorphisms; STAM2; signal transducing adaptor molecule 2; TKI; tyrosine kinase inhibitor; VEGF; vascular endothelial growth factor; VEGFR; VEGF receptorAcquired resistance; Cancer; Phosphatase; Receptor tyrosine kinase

The cytostatic activity of NUC-3073, a phosphoramidate prodrug of 5-fluoro-2′-deoxyuridine, is independent of activation by thymidine kinase and insensitive to degradation by phosphorolytic enzymes by Johan Vande Voorde; Sandra Liekens; Christopher McGuigan; Paola G.S. Murziani; Magdalena Slusarczyk; Jan Balzarini (pp. 441-452).

A novel phosphoramidate nucleotide prodrug of the anticancer nucleoside analogue 5-fluoro-2′-deoxyuridine (5-FdUrd) was synthesized and evaluated for its cytostatic activity. Whereas 5-FdUrd substantially lost its cytostatic potential in thymidine kinase (TK)-deficient murine leukaemia L1210 and human lymphocyte CEM cell cultures, NUC-3073 markedly kept its antiproliferative activity in TK-deficient tumour cells, and thus is largely independent of intracellular TK activity to exert its cytostatic action. NUC-3073 was found to inhibit thymidylate synthase (TS) in the TK-deficient and wild-type cell lines at drug concentrations that correlated well with its cytostatic activity in these cells. NUC-3073 does not seem to be susceptible to inactivation by catabolic enzymes such as thymidine phosphorylase (TP) and uridine phosphorylase (UP). These findings are in line with our observations that 5-FdUrd, but not NUC-3073, substantially loses its cytostatic potential in the presence of TP-expressing mycoplasmas in the tumour cell cultures. Therefore, we propose NUC-3073 as a novel 5-FdUrd phosphoramidate prodrug that (i) may circumvent potential resistance mechanisms of tumour cells (e.g. decreased TK activity) and (ii) is not degraded by catabolic enzymes such as TP which is often upregulated in tumour cells or expressed in mycoplasma-infected tumour tissue.

Keywords: Nucleoside analogues; Cancer; Phosphoramidate prodrugs; Mycoplasma; Thymidine phosphorylase; 5-Fluoro-2′-deoxyuridine (5-FdUrd)

Helenalin bypasses Bcl-2-mediated cell death resistance by inhibiting NF-κB and promoting reactive oxygen species generation by Ruth Hoffmann; Karin von Schwarzenberg; Nancy López-Antón; Anita Rudy; Gerhard Wanner; Verena M. Dirsch; Angelika M. Vollmar (pp. 453-463).

Mechanism how helenalin bypasses Bcl-2 mediated death resistance.Evasion of cell death by overexpression of anti-apoptotic proteins, such as Bcl-2, is commonly observed in cancer cells leading to a lack of response to chemotherapy. Hence, there is a need to find new chemotherapeutic agents that are able to overcome chemoresistance mediated by Bcl-2 and to understand their mechanisms of action. Helenalin, a sesquiterpene lactone (STL), induces cell death and abrogates clonal survival in a highly apoptosis-resistant Bcl-2 overexpressing Jurkat cell line as well as in two other Bcl-2 overexpressing solid tumor cell lines (mammary MCF-7; pancreatic L6.3pl). This effect is not achieved by directly affecting the mitochondria-protective function of Bcl-2 in the intrinsic pathway of apoptosis since Bcl-2 overexpressing Jurkat cells do not show cytochrome c release and dissipation of mitochondrial membrane potential upon helenalin treatment. Moreover, helenalin induces an atypical form of cell death with necrotic features in Bcl-2 overexpressing cells, neither activating classical mediators of apoptosis (caspases, AIF, Omi/HtrA2, Apaf/apoptosome) nor ER-stress mediators (BiP/GRP78 and CHOP/GADD153), nor autophagy pathways (LC3 conversion). In contrast, helenalin was found to inhibit NF-κB activation that was considerably increased in Bcl-2 overexpressing Jurkat cells and promotes cell survival. Moreover, we identified reactive oxygen species (ROS) and free intracellular iron as mediators of helenalin-induced cell death whereas activation of JNK and abrogation of Akt activity did not contribute to helenalin-elicited cell death. Our results highlight the NF-κB inhibitor helenalin as a promising chemotherapeutic agent to overcome Bcl-2-induced cell death resistance.

Keywords: Sesquiterpene lactone; Apoptosis; Chemoresistance; Autophagy; ER-stress

Anticancer activity of thymoquinone in breast cancer cells: Possible involvement of PPAR-γ pathway by Chern Chiuh Woo; Ser Yue Loo; Veronica Gee; Chun Wei Yap; Gautam Sethi; Alan Prem Kumar; Kwong Huat Benny Tan (pp. 464-475).

Thymoquinone (TQ), an active ingredient of Nigella sativa, has been reported to exhibit anti-oxidant, anti-inflammatory and anti-tumor activities through mechanism(s) that is not fully understood. In this study, we report the anticancer effects of TQ on breast cancer cells, and its potential effect on the PPAR-γ activation pathway. We found that TQ exerted strong anti-proliferative effect in breast cancer cells and, when combined with doxorubicin and 5-fluorouracil, increased cytotoxicity. TQ was found to increase sub-G1 accumulation and annexin-V positive staining, indicating apoptotic induction. In addition, TQ activated caspases 8, 9 and 7 in a dose-dependent manner. Migration and invasive properties of MDA-MB-231 cells were also reduced in the presence of TQ. Interestingly, we report for the first time that TQ was able to increase PPAR-γ activity and down-regulate the expression of the genes for Bcl-2, Bcl-xL and survivin in breast cancer cells. More importantly, the increase in PPAR-γ activity was prevented in the presence of PPAR-γ specific inhibitor and PPAR-γ dominant negative plasmid, suggesting that TQ may act as a ligand of PPAR-γ. Also, we observed using molecular docking analysis that TQ indeed formed interactions with 7 polar residues and 6 non-polar residues within the ligand-binding pocket of PPAR-γ that are reported to be critical for its activity. Taken together, our novel observations suggest that TQ may have potential implication in breast cancer prevention and treatment, and show for the first time that the anti-tumor effect of TQ may also be mediated through modulation of the PPAR-γ activation pathway.

Keywords: Thymoquinone; Breast cancer; PPAR-γ; Molecular docking; Apoptosis

Hypoxia modulates the effect of dihydroartemisinin on endothelial cells by S. D’Alessandro; N. Basilico; Y. Corbett; D. Scaccabarozzi; F. Omodeo-Salè; M. Saresella; I. Marventano; M. Vaillant; P. Olliaro; D. Taramelli (pp. 476-484).

Artemisinin derivatives, the current cornerstone of malaria treatment, possess also anti-angiogenic and anti-tumor activity. Hypoxia plays a crucial role both in severe malaria (as a consequence of the cytoadherence of infected erythrocytes to the microvasculature) and in cancer (due to the restricted blood supply in the growing tumor mass). However, the consequences of hypoxia onto the effects of artemisinins is under-researched.This study aimed at assessing how the inhibition of microvascular endothelial cell (HMEC-1) growth induced by dihydroartemisinin (DHA, an antimalarial drug and the active metabolite of currently in-use artemisinins) is affected by oxygen tension.Low doses of DHA (achieved in the patients’ plasma when treating malaria) were more inhibitory in hypoxia, whereas high doses (required for anti-angiogenic or anti-tumor activity) were more effective in normoxia. The peroxide bridge is essential for cellular toxicity (deoxyDHA was inactive). High doses of DHA caused HMEC-1 apoptosis and G2 cell cycle arrest. Effects were mediated by the generation of oxidative stress as demonstrated by DCF-DA fluorescence and membrane lipid peroxidation analysis.Overall, these results suggest that DHA inhibition of endothelial cell growth is related to the level of tissue oxygenation and drug concentration. This should be considered when studying both the effects of artemisinin derivatives as antimalarials and the potential therapeutic applications of these drugs as anti-tumor agents.

Keywords: Abbreviations; BSO; buthionine sulfoximine; CPT; camptothecin; DCF-DA; dihydrodichlorofluorescein diacetate; DeoxyDHA; dihydrodeoxyartemisinin; DHA; dihydroartemisinin; EC; endothelial cell; GSH; glutathione; HIF-1α; hypoxia inducible factor; HMEC-1; human microvascular endothelial cells; RBC; red blood cell; Tetraoxane; dimethyltetraoxodispiro-hexadecan; VEGF; vascular endothelial growth factorHypoxia; Dihydroartemisinin (DHA); Endothelial cells; Cell proliferation; Malaria

Hyperoxia attenuates the inhibitory effect of nitric oxide donors on HIF prolyl-4-hydroxylase-2: Implication on discriminative effect of nitric oxide on HIF prolyl-4-hydroxylase-2 and collagen prolyl-4-hydroxylase by Soohwan Yum; Jeongyoun Choi; Sungchae Hong; Myung Hee Park; Jaewon Lee; Nam-Chul Ha; Yunjin Jung (pp. 485-490).

Prolyl 4-hydroxylases (P4Hs), such as collagen prolyl-4-hydroxylases (CPHs) and hypoxia inducible factor prolyl-4-hydroxylases (HPHs), have recently been recognized as promising drug targets for the treatment of fibrotic and ischemic diseases. CPHs and HPHs catalyze identical metabolic reactions, yet lead to quite different physiological consequences, collagen synthesis and the regulation of oxygen homeostasis. Selective modulation of the two enzymes should provide a therapeutic benefit upon pharmacotherapy. In an in vitro VHL capture assay, hydroxylation of the 19mer HIF peptide (corresponding to HIF-1α residues 556–574) by HPH-2 was effectively prevented by nitric oxide (NO) donors, (±)-S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione. The NO donors also caused inhibition of HPHs and accumulation of nonhydroxylated HIF-1α protein in A549 human lung adenocarcinoma cells. Hyperoxia (100% O₂) attenuated both NO donor-induced accumulation of HIF-1α and inhibition of HPH-mediated hydroxylation. In the presence of a proteasome inhibitor, MG132, the hyperoxia-mediated degradation of HIF-1α was deterred and hydroxylated HIF-1α was detected. SNAP, while being an effective inhibitor of proline 4-hydroxylation of HIF-1α by HPH-2, did not diminish proline hydroxylation of collagen by CPHs. Our data suggest that NO inhibits HPH-2 via competing with dioxygen and that the discriminative effect of NO on CPHs and HPH-2 is attributable to the difference in the affinity of the two enzymes toward dioxygen.

Keywords: Abbreviations; NO; Nitric oxide; GSNO; S-nitrosoglutathione; SNAP; (±)-S-nitroso-N-acetylpenicillamine; HIF-1α; Hypoxia inducible factor-1 alpha; HPH; HIF prolyl-4-hydroxylase; VHL; von Hippel-Lindau; IVT; In vitro; translated; CAPE; Caffeic acid phenethyl ester; P4Hs; Prolyl 4-hydroxylases; CPHs; Collagen prolyl-4-hydroxylasesNitric oxide; Hyperoxia; HIF polyl-4-hydroxylase; Collagen prolyl-4-hydroxylase; Hypoxia inducible factor

Aliskiren affects fatty-acid uptake and lipid-related genes in rodent and human cardiomyocytes by Diego Rodríguez-Penas; Sandra Feijóo-Bandín; Pamela V. Lear; Ana Mosquera-Leal; Vanessa García-Rúa; Manuel F. Otero; Miguel Rivera; Oreste Gualillo; José Ramón González-Juanatey; Francisca Lago (pp. 491-504).

We investigated whether the direct renin inhibitor aliskiren can affect metabolism in cardiomyocytes from rat, mouse and human sources.At 10–50μmol/L, aliskiren significantly increased medium-chain-fatty-acid uptake in primary-cultured neonatal-rat and HL-1 adult-mouse-derived cardiomyocytes (BODIPY-induced fluorescence intensity). The fatty-acid transporter CD-36 was correspondingly translocated to, but the glucose transporter Glut-4 away from, the sarcoplasmic reticulum/plasma membrane, in primary-cultured neonatal-rat (CD-36, Glut-4) and adult-human (CD-36) cardiomyocytes (confocal immunocytochemistry). Immunoblotting showed that aliskiren induced phosphorylation of ERK1/2 in cardiomyocytes from all three sources; responses were dose- and time-dependent, unaffected by renin treatment, and did not cause alterations in expression of (P)R or Igf2/M6P receptors. Microarray analysis of the complete genome of aliskiren-treated neonatal-rat cardiomyocytes, with RT-qPCR and immunoblot confirmation assays in rat and human primary cardiomyocytes, showed that aliskiren up-regulated mRNA and increased protein expression of several enzymes important in lipid and glucose metabolism and in cholesterol biosynthesis. Cardiomyocyte cell-cycle and viability were unaffected by aliskiren.Aliskiren can induce changes in fatty-acid and glucose uptake and expression of key enzymes of lipid and cholesterol metabolism, which are not associated with increased expression of (P)R or Igf2/M6P receptors, in cultured cardiomyocytes.

Keywords: Cardiomyocytes; Aliskiren; Metabolism; Lipids; Cholesterol; Glucose

Differential dephosphorylation of the Protein Kinase C-zeta (PKCζ) in an integrin αIIbβ3-dependent manner in platelets by Azad Mayanglambam; Dheeraj Bhavanasi; K. Vinod Vijayan; Satya P. Kunapuli (pp. 505-513).

Differential dephosphorylation of Protein Kinase C-zeta (PKC() in an integrin (IIb(3-dependent manner in platelets.Protein kinase C-zeta (PKCζ), an atypical isoform of the PKC family of protein serine/threonine kinases, is expressed in human platelets. However, the mechanisms of its activation and the regulation of its activity in platelets are not known. We have found that under basal resting conditions, PKCζ has a high phosphorylation status at the activation loop threonine 410 (T410) and the turn motif (autophosphorylation site) threonine 560 (T560), both of which have been shown to be important for its catalytic activity. After stimulation with agonist under stirring conditions, the T410 residue was dephosphorylated in a time- and concentration-dependent manner, while the T560 phosphorylation remained unaffected. The T410 dephosphorylation could be significantly prevented by blocking the binding of fibrinogen to integrin αIIbβ3 with an antagonist, SC-57101; or by okadaic acid used at concentrations that inhibits protein serine/threonine phosphatases PP1 and PP2A in vitro. The dephosphorylation of T410 residue on PKCζ was also observed in PP1cγ null murine platelets after agonist stimulation, suggesting that other isoforms of PP1c or another phosphatase could be responsible for this dephosphorylation event. We conclude that human platelets express PKCζ, and it may be constitutively phosphorylated at the activation loop threonine 410 and the turn motif threonine 560 under basal resting conditions, which are differentially dephosphorylated by outside-in signaling. This differential dephosphorylation of PKCζ might be an important regulatory mechanism for platelet functional responses.

Keywords: Abbreviations; PKC; protein kinase C; DAG; diacylglycerol; PI3-K; phosphoinositide 3-kinase; PIP3; phosphatidylinositol (3,4,5)-trisphosphate; PKD1; 3-phosphoinositide dependent protein kinase-1; PLD2; phospholipase D2; PP1; serine/threonine protein phosphatase 1; PP2A; serine/threonine protein phosphatase 2AProtein kinase C; Phosphorylation; Dephosphorylation; Phosphatase; Integrin

Endothelial cell-specific aryl hydrocarbon receptor knockout mice exhibit hypotension mediated, in part, by an attenuated angiotensin II responsiveness by Larry N. Agbor; Khalid M. Elased; Mary K. Walker (pp. 514-523).

Hypotension in aryl hydrocarbon receptor knockout mice ( ahr^−/−) is mediated, in part, by a reduced contribution of angiotensin (Ang) II to basal blood pressure (BP). Since AHR is highly expressed in endothelial cells (EC), we hypothesized that EC-specific ahr^−/− (EC ahr^−/−) mice would exhibit a similar phenotype. We generated EC ahr^−/− mice by crossing AHR floxed mice ( ahr^fx/fx) to mice expressing Cre recombinase driven by an EC-specific promoter. BP was assessed by radiotelemetry prior to and following an acute injection of Ang II or chronic treatment with an angiotensin converting enzyme inhibitor (ACEi). EC ahr^−/− mice were hypotensive (EC ahr^+/+: 116.1±1.4; EC ahr^−/−: 107.4±2.0mmHg, n=11, p<0.05) and exhibited significantly different responses to Ang II and ACEi. While Ang II increased BP in both genotypes, the increase was sustained in EC ahr^+/+, whereas the increase in EC ahr^−/− mice steadily declined. Area under the curve analysis showed that Ang II-induced increase in diastolic BP (DBP) over 30min was significantly lower in EC ahr^−/− mice (EC ahr^+/+ 1297±223mmHg/30min; EC ahr^−/−_AUC: 504±138mmHg/30min, p<0.05). In contrast, while ACEi decreased BP in both genotypes, the subsequent rise in DBP after treatment was significantly delayed in the EC ahr^−/− mice. EC ahr^−/− mice also exhibited reduced vascular and adipose Ang II type 1 receptor (AT1R) expression, and reduced aortic Ang II-dependent vasoconstriction in the presence of vascular adipose. Taken together these data suggest that hypotension in EC ahr^−/− mice results from reduced vascular responsiveness to Ang II that is influenced by AT1R expression and adipose.

Keywords: Abbreviations; AHR; aryl hydrocarbon receptor; TCDD; 2,3,7,8-tetrachlorodibenzo-; p; -dioxin; Cre; Cre-recombinase; EC; endothelial cell; Ahr; fx; /; ^fx; floxed; ahr; allele; ACE; angiotensin converting enzyme; ACEi; angiotensin converting enzyme inhibitor; Agt; angiotensinogen; Ang II; angiotensin II; MAP; mean arterial pressure; BP; blood pressure; NOx; nitrates/nitrites; NO; nitric oxide; RAS; renin-angiotensin system; AT1R; angiotensin 1 receptor; PRA; plasma renin activity; PVAT; perivascular adipose tissueAryl hydrocarbon receptor; Endothelial cells; Blood pressure; Hypotension; Angiotensin II; Adipose

Psoralidin, a dual inhibitor of COX-2 and 5-LOX, regulates ionizing radiation (IR)-induced pulmonary inflammation by Hee Jung Yang; HyeSook Youn; Ki Moon Seong; Young Ju Yun; Wanyeon Kim; Young Ha Kim; Ji Young Lee; Cha Soon Kim; Young-Woo Jin; BuHyun Youn (pp. 524-534).

Radiotherapy is the most significant non-surgical cure for the elimination of tumor, however it is restricted by two major problems: radioresistance and normal tissue damage. Efficiency improvement on radiotherapy is demanded to achieve cancer treatment. We focused on radiation-induced normal cell damage, and are concerned about inflammation reported to act as a main limiting factor in the radiotherapy. Psoralidin, a coumestan derivative isolated from the seed of Psoralea corylifolia, has been studied for anti-cancer and anti-bacterial properties. However, little is known regarding its effects on IR-induced pulmonary inflammation. The aim of this study is to investigate mechanisms of IR-induced inflammation and to examine therapeutic mechanisms of psoralidin in human normal lung fibroblasts and mice. Here, we demonstrated that IR-induced ROS activated cyclooxygenases-2 (COX-2) and 5-lipoxygenase (5-LOX) pathway in HFL-1 and MRC-5 cells. Psoralidin inhibited the IR-induced COX-2 expression and PGE₂ production through regulation of PI3K/Akt and NF-κB pathway. Also, psoralidin blocked IR-induced LTB₄ production, and it was due to direct interaction of psoralidin and 5-lipoxygenase activating protein (FLAP) in 5-LOX pathway. IR-induced fibroblast migration was notably attenuated in the presence of psoralidin. Moreover, in vivo results from mouse lung indicate that psoralidin suppresses IR-induced expression of pro-inflammatory cytokines (TNF-α, TGF-β, IL-6 and IL-1 α/β) and ICAM-1. Taken together, our findings reveal a regulatory mechanism of IR-induced pulmonary inflammation in human normal lung fibroblast and mice, and suggest that psoralidin may be useful as a potential lead compound for development of a better radiopreventive agent against radiation-induced normal tissue injury.

Keywords: Abbreviations; AA; arachidonic acid; COX; cyclooxygenase; ERK; extracellular signal-regulated kinase; DCFH-DA; 2′,7′-dichlorodihydrofluorescin diacetate; FLAP; 5-lipoxygenase activating protein; GAPDH; glyceraldehyde-3-phosphate dehydrogenase; ICAM; intercellular adhesion molecule; IκBα; inhibitors of NF-κB α; IL; interleukin; IR; ionizing radiation; ITC; isothermal titration calorimetry; JNK; c-Jun N-terminal kinase; LOX; lipoxygenase; LT; leukotriene; MAPK; mitogen activated protein kinase; MTT; methylthiazolyldiphenyl-tetrazolium bromide; NF-κB; nuclear factor-κB; PDTC; pyrrolidine dithiocarbamate; PG; prostaglandin; PI3K; phosphoinositide3-kinase; ROS; reactive oxygen species; TGF-β; transforming growth factor-β; TNF-α; tumor necrosis factor-αIonizing radiation; Psoralidin; COX-2; 5-LOX; Anti-inflammation

Benzylidenemalononitrile compounds as activators of cell resistance to oxidative stress and modulators of multiple signaling pathways. A structure–activity relationship study by Kyril Turpaev; Mikhail Ermolenko; Thierry Cresteil; Jean Claude Drapier (pp. 535-547).

Benzylidenemalononitrile (BMN) tyrphostins are well known as potent tyrosine kinase inhibitors. Moreover, in recent years it has been recognized that members of the tyrphostin family possess additional biological activities independent of their ability to inhibit protein tyrosine kinases. In this study, we examined the relationship between the structure of 49 BMNs and related compounds, and their capacity to induce heme oxygenase 1 (HO-1) gene expression in U937 human monocytic cells, to activate upstream signaling pathways and to protect cells against menadione-induced oxidative stress. It was found that the electron-withdrawing (NO₂, CN, halogen) groups in BMN molecules and double meta-MeO substituents increased the HO-1 gene induction, while the electron-donating groups in ortho/ para position (OH, MeO and N-morpholino) significantly decreased it. The magnitude of activation of c-Jun, Nrf2, p38 MAPK, and p70S6K correlated with specific substitution patterns in the BMN structure. BMN-dependent maximal up-regulation of HO-1 required parallel increase in Nrf2 and phospho-c-Jun cellular levels. Liquid chromatography mass spectrometry (LC–MS) analysis revealed that BMNs can generate conjugates with one or two glutathione equivalent(s). This study supports the hypothesis that BMNs induce the expression of protective genes by alkylating sensitive cysteine residues of regulatory factors.

Keywords: Abbreviations; ARE; antioxidant response element; BMN; benzylidenemalononitrile(s); ELSD; evaporative light scattering detection; ESI; electrospray ionization; GSH; glutathione; HO-1; heme oxygenase 1; IL-8; interleukin 8; LC–MS; liquid chromatography mass spectrometry; MTT; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; p70S6K; p70 S6 kinaseBenzylidenemalononitriles; Oxidative stress; Heme oxygenase; Nrf2; c-Jun

N-acetyl-l-cysteine (NAC) inhibit mucin synthesis and pro-inflammatory mediators in alveolar type II epithelial cells infected with influenza virus A and B and with respiratory syncytial virus (RSV) by Manuel Mata; Esteban Morcillo; Concepcion Gimeno; Julio Cortijo (pp. 548-555).

64% of chronic obstructive pulmonary disease (COPD) exacerbations are caused by respiratory infections including influenza (strains A and B) and respiratory syncytial virus (RSV). They affect the airway epithelium increasing inflammatory and apoptosis events through mechanisms involving ROS generation, and induce the release of mucins from epithelial cells that are involved in the deterioration of the patient's health during the course of the disease. The antioxidant NAC has proved useful in the management of COPD reducing symptoms, exacerbations and accelerated lung function decline. It has been shown to inhibit influenza virus replication and to diminish the release of inflammatory and apoptotic mediators during virus infection. The main objective of this study is to analyze the effects of NAC in modulating MUC5AC over-expression and release in an in vitro infection model of alveolar type II A549 cells infected with influenza (strains A and B) and RSV. We have also analyzed virus replication and different pro-inflammatory responses. Our results indicate a significant induction of MUC5AC, IL8, IL6 and TNF-alpha that is strongly inhibited by NAC at the expression and at the release level. It also decreased the intracellular H₂O₂ concentration and restored the intracellular total thiol contents. Mechanisms of NAC included inhibition of NF-κB translocation to the cellular nucleus and phosphorylation of MAPK p38. NAC also inhibited replication of the three viruses under study. This work supports the use of antioxidants in order to ameliorate the inflammatory effects of different viral infections during COPD exacerbations.

Keywords: Influenza; RSV; COPD; NAC; MUC5AC

Sterically stable liposomes improve the therapeutic effect of hepatic stimulator substance on fulminant hepatic failure in rats by Feng Li; Jian-yong Sun; Min Liu; Wei-yue Lu; Ji-yao Wang; Jian-ying Shi (pp. 556-565).

The encapsulation by sterically stabilized liposomes (SSL) enhanced markedly the therapeutic potency of hepatic stimulator substance (HSS) for fulminant hepatic failure in rats.Few drugs have been confirmed to be effective for fulminant hepatic failure (FHF). The purpose of this study was to prepare sterically stable liposomes (SSL) encapsulating hepatic stimulator substance (HSS) and determine their therapeutic effect on FHF.HSS were encapsulated into SSL (HSS-SSL). FHF was induced in rats by thioacetamide (TAA) injection (400mg/kg, three times with a 24-h interval). The agents, including HSS-SSL, SSL, HSS, and sodium chloride (NS), were each injected intravenously 2h after the second and the third TAA injection.Freshly prepared HSS-SSL had a mean size of 93.59nm and the average encapsulation efficiency was 37.20%. HSS encapsulated in SSL showed a longer half life and more potent target to injured livers than free HSS. Twenty-four hours after the third TAA-injection, the survival rate of HSS-SSL-treated rats (80%) was significantly higher than that of rats treated with NS (20%), SSL (25%), or HSS (50%). Histopathologic examination showed that there was the least necrosis and inflammation in the livers of HSS-SSL-treated rats. The incidence of stage 3 or 4 hepatic encephalopathy in HSS-SSL-treated rats was significantly lower than that in rats treated with other agents. The serum pro-inflammatory cytokine levels and hepatic lipid peroxidation levels were both markedly reduced, while hepatocyte proliferative rate was markedly increased after HSS-SSL treatment.Encapsulation by SSL markedly improved the therapeutic effect of HSS on FHF in rats. Encapsulation by SSL may be an effective approach to enhance the therapeutic potency of drugs for FHF.

Keywords: Abbreviations; AUC; area under the curve; BrdU; 5-bromo-2′-deoxyuridine; CC; carrying capacity; FHF; fulminant hepatic failure; HE; hepatic encephalopathy; HSS; hepatic stimulator substance; IL; interleukin; MDA; malondialdehyde; CL; serum clearance; NS; sodium chloride; SD; standard deviation; SSL; sterically stable liposomes; TAA; thioacetamideFulminant hepatic failure; Sterically stable liposomes; Hepatic stimulator substance; Survival; Hepatic encephalopathy

Sections

Personal tools

Biochemical Pharmacology (v.82, #5)

Sections

Personal tools

Local resources

Biochemical Pharmacology (v.82, #5)