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BACKGROUND - Angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARBs) reduce cardiovascular disease (CVD) events, but a recent meta-analysis of selected studies suggested that ARBs may increase cancer risks.
OBJECTIVE - Candesartan, irbesartan, telmisartan, valsartan, and losartan were assessed for incident cancers in 15 large parallel long-term multicenter double-blind clinical trials of these agents involving 138,769 participants.
PATIENTS AND METHODS - Individuals at high CVD risk were randomized to telmisartan (three trials, n=51,878), irbesartan (three trials, n=14,859), valsartan (four trials, n=44,264), candesartan (four trials, n=18,566), and losartan (one trial, n=9193) and followed for 23-60 months. Incident cancer cases were compared in patients randomized to ARBs versus controls. In five trials (n=42,403), the ARBs were compared to ACEi and in 11 trials (n=63,313) to controls without ACEi. In addition, in seven trials (n=47,020), the effect of ARBs with ACEi was compared to ACEi alone and in two trials ARBs with ACEi versus ARB alone (n=25,712).
RESULTS - Overall, there was no excess of cancer incidence with ARB therapy compared to controls in the 15 trials [4549 (6.16%) cases of 73,808 allocated to ARB versus 3856 (6.31%) of 61 106 assigned to non-ARB controls; odds ratio (OR) 1.00, 95% confidence interval (CI) 0.95-1.04] overall or when individual ARBs were examined. ORs comparing combination therapy with ARB along with ACEi versus ACEi was 1.01 (95% CI 0.94-1.10), combination versus ARB alone 1.02 (95% CI 0.91-1.13), ARB alone versus ACEi alone 1.06 (95% CI 0.97-1.16) and ARB versus placebo/control without ACEi 0.97 (95% CI 0.91-1.04). There was no excess of lung, prostate or breast cancer, or overall cancer deaths associated with ARB treatment.
CONCLUSION - There was no significant increase in the overall or site-specific cancer risk from ARBs compared to controls.
Metabotropic glutamate receptor 2/3 (mGluR2/3) agonists were shown previously to nonselectively decrease both cocaine- and food-maintained responding in rats. mGluR2 positive allosteric modulators (PAMs) may represent improved therapeutic compounds because of their modulatory properties and higher selectivity for mGluR2. We analyzed the effects of the selective, brain penetrant, and systemically active mGluR2 PAM potassium 3'-([(2-cyclopentyl-6-7-dimethyl-1-oxo-2,3-dihydro-1H-inden-5-yl)oxy]methyl)biphenyl l-4-carboxylate (BINA) and the mGluR2/3 agonist LY379268 on intravenous cocaine self-administration and cocaine-seeking behavior in rats that had short (1 h, ShA) or long (6 h, LgA) access to cocaine. The effects of BINA on food responding and food-seeking behavior were also analyzed. Finally, we examined the effects of BINA on brain reward function and cocaine-induced reward enhancement using the intracranial self-stimulation procedure. BINA decreased cocaine self-administration in both ShA and LgA rats, with no effect on food self-administration. Alternatively, LY379268 nonselectively decreased both cocaine and food self-administration. BINA decreased cue-induced reinstatement of cocaine seeking with no effect on food seeking. The cocaine-induced enhancement of brain reward function was blocked by BINA, although the highest doses of BINA decreased brain reward function when administered alone, suggesting additive, rather than interactive, effects of BINA and cocaine. In conclusion, BINA attenuated the reinforcing and counteracted the reward-enhancing effects of cocaine and decreased cue-induced cocaine-seeking behavior, without affecting behaviors motivated by food reinforcement. The higher selectivity of BINA compared with an mGluR2/3 agonist for drug- vs food-motivated behaviors suggests a therapeutic role for mGluR2 PAMs for the treatment of cocaine addiction and possibly other drugs of abuse.
Previous preclinical and clinical studies have demonstrated the efficacy of group II metabotropic glutamate receptor (mGluR) agonists as potential antipsychotics. Recent studies utilizing mGluR2-, mGluR3-, and double knockout mice support that the antipsychotic effects of those compounds are mediated by mGluR2. Indeed, biphenyl indanone-A (BINA), an allosteric potentiator of mGluR2, is effective in experimental models of psychosis, blocking phencyclidine (PCP)-induced hyperlocomotion and prepulse inhibition deficits in mice. In this study, we administered the NMDA receptor antagonist PCP (5.6 mg/kg i.p.) to rats, an established animal model predictive of schizophrenia. Here, we show that BINA (32 mg/kg i.p.) attenuated PCP-induced locomotor activity in rats. Using behaviorally relevant doses of BINA and PCP, we performed pharmacological magnetic resonance imaging (phMRI) to assess the specific brain regions that underlie the psychotomimetic effects of PCP, and examined how BINA modulated the PCP-induced functional changes in vivo. In anesthetized rats, acute administration of PCP produced robust, sustained blood oxygenation level-dependent (BOLD) activation in specific cortical, limbic, thalamic, and striatal regions. Pretreatment with BINA suppressed the amplitude of the BOLD response to PCP in the prefrontal cortex, caudaute-putamen, nucleus accumbens, and mediodorsal thalamus. Our results show key brain structures underlying PCP-induced behaviors in a preclinical model of schizophrenia, and, importantly, its reversal by potentiation of mGluR2 by BINA, revealing specific brain regions functionally involved in its pharmacological action. Finally, our findings bolster the growing body of evidence that mGluR2 is a viable target for the treatment of schizophrenia.
2010 IBRO. Published by Elsevier Ltd. All rights reserved.
Fifty-one chemicals including derivatives of 16 flavonoids, three stilbenes, six pyrenes, seven naphthalenes, seven phenanthrenes, 10 biphenyls, 17beta-estradiol, and estrone were examined for their abilities to induce reverse type I binding spectra with human cytochrome P450 (P450) 1B1 and to inhibit 7-ethoxyresorufin O-deethylation (EROD) activities catalyzed by P450 1B1. Forty-nine chemicals showed reverse type I spectra with P450 1B1, and we found that 3,5,7-trihydroxyflavone, 3',4'-dimethoxy-5,7-dihydroxyflavone, 4'-methoxy-5,7-dihydroxyflavone, alpha- and beta-naphthoflavones, 2,4,3',5'-tetramethoxystilbene, pyrene, and several acetylenic pyrenes and phenanthrenes were strong inducers of the spectra and also potent inhibitors of EROD activities catalyzed by P450 1B1. The spectral dissociation constant (K(s)) and the magnitude of the binding (DeltaA(max)/K(s)) of 49 chemicals were correlated with the inhibition potencies of EROD activities by these chemicals [correlation coefficients (r) of 0.72 and 0.74, respectively]. The K(s) and DeltaA(max)/K(s) values were more correlated with IC(50) values when compared in a group of derivatives of flavonoids, stilbenes, and estrogens (r = 0.81 and 0.88, respectively) or a group of derivatives of pyrenes, naphthalenes, phenanthrenes, and biphenyls (r = 0.88 and 0.91, respectively). Among 14 flavonoids examined, 3,5,7-trihydroxyflavone and 4'-methoxy- and 3',4'-dimethoxy-5,7-dihydroxyflavone were more active than flavone in interacting with P450 1B1, but the respective 7,8-dihydroxyflavones were less active. Pyrene itself was highly active in interacting with P450 1B1, but its binding was slightly decreased when substituted with acetylenic groups. In contrast, substitution of naphthalene with methyl and ethyl propargyl ethers led to more interaction with P450 1B1 than with naphthalene itself. Similarly, substitution on phenanthrene or biphenyl with acetylenic groups and propargyl ethers increased affinities to P450 1B1. These results suggest that the reverse type I binding of chemicals to P450 1B1 may determine how they interact with and inhibit the catalytic activity of the enzyme. Substitutions on the compounds with various acetylenic groups and propargyl ethers cause an increase or decrease of their affinities to P450 1B1, depending on the parent compound used.
Honokiol, a compound extracted from Magnolia officinalis, has antitumor and antiangiogenic properties in several tumor models in vivo. Among the downstream pathways inhibited by honokiol is nuclear factor kappa beta (NFkappabeta). A prime physiologic stimulus of NFkappabeta is reactive oxygen species. The chemical structure of honokiol suggests that it may be an effective scavenger of reactive oxygen species. In this work, we have studied the reactions of honokiol with superoxide and peroxyl radicals in cell-free and cellular systems using electron spin resonance (ESR) and high-performance liquid chromatography (HPLC) techniques. Honokiol efficiently scavenged superoxide radicals in xanthine oxidase and cytochrome P-450 cell-free systems with the rate constant 3.2x10(5)M(-1)s(-1), which is similar to reactivity of ascorbic acid but 20-times higher than reactivity of vitamin E analog trolox. Honokiol potently scavenged intracellular superoxide within melanoma cells. In addition, honokiol scavenged peroxyl radicals generated by 2,2'-azo-bis(2-amidinopropane hydrochloride) (AAPH). The rate constant of the reaction of honokiol with peroxyl radicals (1.4x10(6)M(-1)s(-1)) was calculated from the competition with spin trap 5-(ethoxycarbonyl)-5-methyl-1-pyrroline N-oxide (EMPO), and was found close to reactivity of trolox (2.5x10(6)M(-1)s(-1)). Therefore, honokiol is an effective scavenger of both superoxide and peroxyl radicals, which may be important for physiological activity of honokiol.
PURPOSE - Elevated phospholipase D (PLD) activity provides a survival signal in several human cancer cell lines and suppresses apoptosis when cells are subjected to the stress of serum withdrawal. Thus, targeting PLD survival signals has potential to suppress survival in cancer cells that depend on PLD for survival. Honokiol is a compound that suppresses tumor growth in mouse models. The purpose of this study was to investigate the effect of honokiol on PLD survival signals and the Ras dependence of these signals.
EXPERIMENTAL DESIGN - The effect of honokiol upon PLD activity was examined in human cancer cell lines where PLD activity provides a survival signal. The dependence of PLD survival signals on Ras was investigated, as was the effect of honokiol on Ras activation.
RESULTS - We report here that honokiol suppresses PLD activity in human cancer cells where PLD has been shown to suppress apoptosis. PLD activity is commonly elevated in response to the stress of serum withdrawal, and, importantly, the stress-induced increase in PLD activity is selectively suppressed by honokiol. The stress-induced increase in PLD activity was accompanied by increased Ras activation, and the stress-induced increase in PLD activity in MDA-MB-231 breast cancer cells was dependent on a Ras. The PLD activity was also dependent on the GTPases RalA and ADP ribosylation factor. Importantly, honokiol suppressed Ras activation.
CONCLUSION - The data provided here indicate that honokiol may be a valuable therapeutic reagent for targeting a large number of human cancers that depend on Ras and PLD for their survival.
Previous work has shown that integrin alpha1-null Alport mice exhibit attenuated glomerular disease with decreased matrix accumulation and live much longer than strain-matched Alport mice. However, the mechanism underlying this observation is unknown. Here we show that glomerular gelatinase expression, specifically matrix metalloproteinase-2 (MMP-2), MMP-9, and MMP-14, was significantly elevated in both integrin alpha1-null mice and integrin alpha1-null Alport mice relative to wild-type mice; however, only MMP-9 was elevated in glomeruli of Alport mice that express integrin alpha1. Similarly, cultured mesangial cells from alpha1-null mice showed elevated expression levels of all three MMPs, whereas mesangial cells from Alport mice show elevated expression levels of only MMP-9. In both glomeruli and cultured mesangial cells isolated from integrin alpha1-null mice, activation of the p38 and ERK branches of the mitogen-activated protein kinase pathway was also observed. The use of small molecule inhibitors demonstrated that the activation of the p38, but not ERK, pathway was linked to elevated MMP-2, -9, and -14 expression levels in mesangial cells from integrin alpha1-null mice. In contrast, elevated MMP-9 levels in mesangial cells from Alport mice were linked to ERK pathway activation. Blockade of gelatinase activity using a small molecule inhibitor (BAY-12-9566) ameliorated progression of proteinuria and restored the architecture of the glomerular basement membrane in alpha1 integrin-null Alport mice, suggesting that elevated gelatinase activity exacerbates glomerular disease progression in these mice.
Adipocyte fatty-acid-binding protein, aP2 (FABP4) is expressed in adipocytes and macrophages, and integrates inflammatory and metabolic responses. Studies in aP2-deficient mice have shown that this lipid chaperone has a significant role in several aspects of metabolic syndrome, including type 2 diabetes and atherosclerosis. Here we demonstrate that an orally active small-molecule inhibitor of aP2 is an effective therapeutic agent against severe atherosclerosis and type 2 diabetes in mouse models. In macrophage and adipocyte cell lines with or without aP2, we also show the target specificity of this chemical intervention and its mechanisms of action on metabolic and inflammatory pathways. Our findings demonstrate that targeting aP2 with small-molecule inhibitors is possible and can lead to a new class of powerful therapeutic agents to prevent and treat metabolic diseases such as type 2 diabetes and atherosclerosis.
Recent clinical studies reveal that selective agonists of group II metabotropic glutamate (mGlu) receptors have robust efficacy in treating positive and negative symptoms in patients with schizophrenia. Group II mGlu receptor agonists also modulate the in vivo activity of psychotomimetic drugs and reduce the ability of psychotomimetic hallucinogens to increase glutamatergic transmission. Because increased excitation of the medial prefrontal cortex (mPFC) has been implicated in pathophysiology of schizophrenia, the ability of group II mGlu receptor agonists to reduce hallucinogenic drug action in this region is believed to be directly related to their antipsychotic efficacy. A novel class of ligands, termed positive allosteric modulators, has recently been identified, displaying exceptional mGlu2 receptor selectivity. These compounds do not activate mGlu2 receptors directly but potentiate the ability of glutamate and other agonists to activate this receptor. We now report that the mGlu2 receptor-selective positive allosteric modulator biphenyl-indanone A (BINA) modulates excitatory neurotransmission in the mPFC and attenuates the in vivo actions of the hallucinogenic 5-HT(2A/2C) receptor agonist (-)2,5-dimethoxy-4-bromoamphetamine [(-)DOB]. BINA attenuates serotonin-induced increases in spontaneous excitatory postsynaptic currents in the mPFC, mimicking the effect of the mGlu2/3 receptor agonist (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV). In addition, BINA reduced (-)DOB-induced head twitch behavior and Fos expression in mPFC, effects reversed by pretreatment with the mGlu2/3 receptor antagonist 2S-2-amino-2-(1S,2S-2-carboxycyclopropan-1-yl) -3 - (xanth-9-yl-)propionic acid (LY341495). These data confirm the relevance of excitatory signaling in the mPFC to the behavioral actions of hallucinogens and further support the targeting of mGlu2 receptors as a novel strategy for treating glutamatergic dysfunction in schizophrenia.