Pharmacoproteomic effects of isoniazid, ethambutol, and N-geranyl-N'-(2-adamantyl)ethane-1,2-diamine (SQ109) on Mycobacterium tuberculosis H37Rv.
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The present study was aimed at fingerprinting pharmacoproteomic alterations of the Mycobacterium tuberculosis H37Rv strain induced by antitubercular drugs isoniazid (INH), ethambutol (EMB), and SQ109 [N-geranyl-N'-(2-adamantyl)ethane-1,2-diamine, a novel 1,2-diamine-based EMB analog], providing new understanding of pharmacoproteomic mechanisms of each and exploring new drug targets. The three drugs produced significant down-regulation of 13 proteins, including immunogenic ModD, Mpt64, with proteins from the Pro-Glu family being inhibited the most. Alternatively, the three drugs up-regulated 17 proteins, including secreted antigenic proteins ESAT-6 and CFP-10. Among these, ESAT-6 and AphC were most affected by INH, whereas EMB had the greatest effect on ESAT-6. All three drugs produced only moderate up-regulation of aerobic and iron metabolism proteins, i.e., electron transfer flavoprotein Fix A and Fix B, and ferritin-like protein BfrB, suggesting that the interruption of microbacterial energy metabolism is not a primary mechanism of action. INH suppressed ATP-dependent DNA/RNA helicase, but up-regulated beta-ketoacyl-acyl carrier protein synthase. These effects may contribute to its bactericidal effects. In contrast, EMB and SQ109 did just the opposite: these drugs up-regulated the helicase and down-regulated the synthase. For most of the H37Rv proteins, similar pharmacoproteomic patterns were found for both EMB and SQ109. None of the drugs significantly regulated expression of chaperonins GroES, GroEL2, and Dnak, suggesting that these drugs do not affect chaperone-mediated nascent polypeptide folding and sorting. The present study identified proteins directly modulated by the actions of INH, EMB, and SQ109 and distinguished INH activity from the diamine antitubercular compounds that inhibit M. tuberculosis H37Rv. (+info)
11beta-HSD1 inhibition ameliorates metabolic syndrome and prevents progression of atherosclerosis in mice.
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The enzyme 11beta-hydroxysteroid dehydrogenase (HSD) type 1 converts inactive cortisone into active cortisol in cells, thereby raising the effective glucocorticoid (GC) tone above serum levels. We report that pharmacologic inhibition of 11beta-HSD1 has a therapeutic effect in mouse models of metabolic syndrome. Administration of a selective, potent 11beta-HSD1 inhibitor lowered body weight, insulin, fasting glucose, triglycerides, and cholesterol in diet-induced obese mice and lowered fasting glucose, insulin, glucagon, triglycerides, and free fatty acids, as well as improved glucose tolerance, in a mouse model of type 2 diabetes. Most importantly, inhibition of 11beta-HSD1 slowed plaque progression in a murine model of atherosclerosis, the key clinical sequela of metabolic syndrome. Mice with a targeted deletion of apolipoprotein E exhibited 84% less accumulation of aortic total cholesterol, as well as lower serum cholesterol and triglycerides, when treated with an 11beta-HSD1 inhibitor. These data provide the first evidence that pharmacologic inhibition of intracellular GC activation can effectively treat atherosclerosis, the key clinical consequence of metabolic syndrome, in addition to its salutary effect on multiple aspects of the metabolic syndrome itself. (+info)
BP-1107 [{2-[4-(2,4-dioxo-thiazolidin-5-ylmethyl)-phenoxy]-ethyl}-methyl-amide]: a novel synthetic thiazolidinedione that inhibits epidermal hyperplasia in psoriatic skin-severe-combined immunodeficient mouse transplants after topical application.
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Recent studies have demonstrated that orally administered thiazolidinedione ligands of the peroxisome proliferator-activated receptor-gamma can ameliorate clinical features of psoriasis in humans. Thiazolidinediones also inhibit the proliferation of psoriatic keratinocytes in monolayer and organ culture, and at least one of these agents (troglitazone) inhibits epidermal hyperplasia of human psoriatic skin transplanted to severe-combined immunodeficient (SCID) mice. In the present study, we show that a novel, synthetic, thiazoladinedione derivative, BP-1107 ({2-[4-(2,4-dioxo-thiazolidin-5-ylmethyl)-phenoxy]-ethyl}-methyl-amide), is capable of inhibiting psoriatic hyperplasia in the SCID mouse transplant model after topical application. Like other thiazolidinediones, BP-1107 inhibits proliferation of rapidly growing keratinocytes in monolayer culture, but compared with these agents, the effective dose of BP-1107 needed to suppress keratinocyte proliferation is much lower. Concentrations of BP-1107 that effectively inhibit keratinocyte function have no detrimental effect on dermal fibroblasts. These data suggest that effective topical antipsoriatic therapy may be provided with this agent. (+info)
Incretin mimetics: promising new therapeutic options in the treatment of type 2 diabetes.
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OBJECTIVE: To review the current state of diabetes treatment from a clinical and management perspective and explore the role that new biologic pharmaceuticals may offer patients who fail to meet or maintain glycemic goals with existing treatment options. SUMMARY: Key clinical areas involve the role that insulin resistance and beta-cell dysfunction/failure play in the progression of type 2 diabetes as well as current treatment modalities and how they address those core defects. Management issues include a discussion of the economics of the disease and the implications of the United Kingdom Prospective Diabetes Study (UKPDS)--that good glucose control reduces the occurrence of microvascular complications and improves quality of life for diabetic patients. While an intensive approach may be costly in the short term, statistics on the rising pandemic of the disease argue compellingly for early and aggressive treatment to delay fatal complications and improve the quality of life for persons suffering from type 2 diabetes. Current pharmaceutical regimens are not successfully enabling patients with type 2 diabetes to reach glycemic goals. The ramifications of this failure have profound repercussions in the managed care organization environment. Fortunately, new treatment modalities are in various stages of development. These will be reviewed with a more in-depth exploration of the potential of incretin mimetics, a new biologic, injectable class of drugs for the treatment of type 2 diabetes. Emphasis will be given to exenatide, an incretin mimetic that demonstrates particular efficacy for patients not achieving glycemic goal with oral medications and are insulin naive. Biologics are administered by injection or infusion and are generally costly. Apart from their cost, however, what is even more critical to managed care executives and decision makers is that these medications indicate a trend in pharmacotherapy, a groundswell of new medications. In addition, few practitioners and even fewer health care executives understand molecular medicine. The key message is that making formulary decisions about these pharmaceuticals will become more pressing every year. CONCLUSION: Managed care executives will be faced with the significant challenge of investing their limited resources in the most clinically and fiscally responsible manner within a milieu of ever increasing pharmacologic options that could significantly strain budgets and result in less than optimal patient outcomes. (+info)
Transcriptional profiling identifies altered intracellular labile iron homeostasis as a contributing factor to the toxicity of adaphostin: decreased vascular endothelial growth factor secretion is independent of hypoxia-inducible factor-1 regulation.
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PURPOSE: Adaphostin was developed as an inhibitor of the p210(bcr-abl) tyrosine kinase, but as its activity is not limited to tumor cell lines containing this translocation, transcriptional profiling was used as a tool to elucidate additional mechanisms responsible for adaphostin cytotoxicity. EXPERIMENTAL DESIGN: Profiles of drug-induced transcriptional changes were measured in three hematopoietic cell lines following 1 and 10 micromol/L adaphostin for 2 to 6 hours and then confirmed with real-time reverse transcription-PCR (2-24 hours). These data indicated altered iron homeostasis, and this was confirmed experimentally. Alteration of vascular endothelial growth factor (VEGF) secretion through hypoxia-inducible factor-1 (HIF-1) regulation was also investigated. RESULTS: Drug-induced genes included heat shock proteins and ubiquitins, but an intriguing response was the induction of ferritins. Measurement of the labile iron pool showed release of chelatable iron immediately after treatment with adaphostin and was quenched with the addition of an iron chelator. Pretreatment of cells with desferrioxamine and N-acetyl-cysteine reduced but did not ablate the sensitivity of the cells to adaphostin, and desferrioxamine was able to modulate adaphostin-induced activation of p38 and inactivation of AKT. VEGF secretion was shown to be reduced in cell lines after the addition of adaphostin but was not dependent on HIF-1. CONCLUSIONS: Adaphostin-induced cytotoxicity is caused in part by a rapid release of free iron, leading to redox perturbations and cell death. Despite this, reduced VEGF secretion was found to be independent of regulation by the redox responsive transcription factor HIF-1. Thus, adaphostin remains an interesting agent with the ability to kill tumor cells directly and modulate angiogenesis. (+info)
An orally active epoxide hydrolase inhibitor lowers blood pressure and provides renal protection in salt-sensitive hypertension.
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The present study tested the hypothesis that increasing epoxyeicosatrienoic acids by inhibition of soluble epoxide hydrolase (sEH) would lower blood pressure and ameliorate renal damage in salt-sensitive hypertension. Rats were infused with angiotensin and fed a normal-salt diet or an 8% NaCl diet for 14 days. The sEH inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), was given orally to angiotensin-infused animals during the 14-day period. Plasma AUDA metabolite levels were measured, and they averaged 10+/-2 ng/mL in normal-salt angiotensin hypertension and 19+/-3 ng/mL in high-salt angiotensin hypertension on day 14 in the animals administered the sEH inhibitor. Mean arterial blood pressure averaged 161+/-4 mm Hg in normal-salt and 172+/-5 mm Hg in the high-salt angiotensin hypertension groups on day 14. EH inhibitor treatment significantly lowered blood pressure to 140+/-5 mm Hg in the normal-salt angiotensin hypertension group and to 151+/-6 mm Hg in the high-salt angiotensin hypertension group on day 14. The lower arterial blood pressures in the AUDA-treated groups were associated with increased urinary epoxide-to-diol ratios. Urinary microalbumin levels were measured, and ED-1 staining was used to determine renal damage and macrophage infiltration in the groups. Two weeks of AUDA treatment decreased urinary microalbumin excretion in the normal-salt and high-salt angiotensin hypertension groups and macrophage number in the high-salt angiotensin hypertension group. These data demonstrate that sEH inhibition lowers blood pressure and ameliorates renal damage in angiotensin-dependent, salt-sensitive hypertension. (+info)
The tyrphostin adaphostin interacts synergistically with proteasome inhibitors to induce apoptosis in human leukemia cells through a reactive oxygen species (ROS)-dependent mechanism.
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Interactions between the tyrphostin adaphostin and proteasome inhibitors (eg, MG-132 and bortezomib) were examined in multiple human leukemia cell lines and primary acute myeloid leukemia (AML) specimens. Cotreatment of Jurkat cells with marginally toxic concentrations of adaphostin and proteasome inhibitors synergistically potentiated mitochondrial damage (eg, cytochrome c release), caspase activation, and apoptosis. Similar interactions occurred in other human leukemia cell types (eg, U937, HL-60, Raji). These interactions were associated with a marked increase in oxidative damage (eg, ROS generation), down-regulation of the Raf/MEK/ERK pathway, and JNK activation. Adaphostin/MG-132 lethality as well as mitochondrial damage, down-regulation of Raf/MEK/ERK, and activation of JNK were attenuated by the free-radical scavenger NAC, suggesting that oxidative damage plays a functional role in antileukemic effects. Ectopic expression of Raf-1 or constitutively active MEK/ERK or genetic interruption of the JNK pathway significantly diminished adaphostin/MG-132-mediated lethality. Interestingly, enforced Raf or MEK/ERK activation partially diminished adaphostin/MG-132-mediated ROS generation, suggesting the existence of an amplification loop. Finally, the adaphostin/MG-132 regimen displayed similar toxicity toward 5 primary AML samples but not normal hematopoietic progenitors (eg, bone marrow CD34+ cells). Collectively, these findings suggest that potentiating oxidative damage by combining adaphostin with proteasome inhibitors warrants attention as an antileukemic strategy. (+info)
Dipeptidyl-peptidase IV converts intact B-type natriuretic peptide into its des-SerPro form.
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BACKGROUND: Analysis of plasma B-type natriuretic peptide (BNP) has suggested the in vivo formation of a truncated form, BNP (3-32), also called des-SerPro-BNP. The objectives of this study were to investigate (a) whether BNP and other natriuretic peptides are truncated by dipeptidyl-peptidase IV (DPP IV/CD26; EC 3.4.14.5) and (b) whether this truncation affects the susceptibility to cleavage by neutral endopeptidase (NEP; EC 3.4.24.11). METHODS: Human BNP (1-32), A-type natriuretic peptide 1-28 (ANP 1-28), and related peptides were incubated with purified DPP IV and with human plasma. In addition, BNP (1-32), BNP (3-32), and ANP (1-28) were subjected to hydrolysis by NEP. Cleavage products were analyzed by mass spectrometry. RESULTS: BNP (1-32) was cleaved by purified DPP IV with a specificity constant of 0.37 x 10(6) L.mol(-1).s(-1). The DPP IV activity in EDTA-plasma was able to truncate BNP (1-32) ex vivo. Addition of Vildagliptin, a specific DPP IV inhibitor, prevented this truncation in a concentration-dependent manner. Under in vitro circumstances in which ANP was hydrolyzed extensively, BNP (1-32) and BNP (3-32) were very resistant to NEP-mediated cleavage. CONCLUSIONS: DPP IV cleaves BNP (1-32) with an efficiency higher than or comparable to several known in vivo substrates of the enzyme. Even after loss of the amino-terminal dipeptide, BNP remains highly resistant to cleavage by NEP. (+info)