Real-world experience with filgotinib for rheumatoid arthritis in Germany : A retrospective chart review

BACKGROUND

Real-world data for filgotinib, a Janus kinase (JAK)1 inhibitor, are limited in patients with rheumatoid arthritis (RA).

OBJECTIVES

To explore real-world filgotinib use in patients with RA in Germany.

MATERIALS AND METHODS

This retrospective chart review included patients aged ≥ 18 years with confirmed moderate to severe RA who initiated filgotinib before December 1, 2021, with ≥ 6 months of medical records available prior to filgotinib initiation or after initial diagnosis. Patient characteristics, prior treatments, reasons for initiating/discontinuing filgotinib, disease activity, dose adjustments and concomitant treatments were recorded.

RESULTS

In total, 301 patients from 20 German rheumatology outpatient units were included. One-third were aged ≥ 65 years and almost half had ≥ 1 cardiovascular (CV) risk factor. Most patients initiated filgotinib as monotherapy (83.7%; 12.7% of whom with glucocorticoids) and at the 200 mg dose (84.7%); higher proportions of those initiating the 100 versus 200 mg dose were aged ≥ 65 years and had renal impairment or ≥ 1 CV risk factor. Oral administration (78.4%), fast onset of action (66.8%) and administration as monotherapy (65.4%) were the most common reasons for initiating filgotinib. At 12 months, 41 (18.4%) patients had discontinued filgotinib, most commonly due to lack of effectiveness. After 6‑months of follow-up, 36.8% of patients had achieved Clinical Disease Activity Index (CDAI) remission and 45.6% had achieved CDAI low disease activity.

CONCLUSIONS

In clinical practice in Germany, reasons for initiating filgotinib in patients with RA were related to dosing flexibility and general JAK inhibitor attributes. Filgotinib was used predominantly as monotherapy and was effective and generally well tolerated; however, longer-term data in larger, prospective cohorts are needed.

Effect of Filgotinib on Body Mass Index (BMI) and Effect of Baseline BMI on the Efficacy and Safety of Filgotinib in Rheumatoid Arthritis

INTRODUCTION

This post hoc analysis of the phase 3 rheumatoid arthritis (RA) filgotinib clinical trial program assessed the effect of filgotinib on body mass index (BMI) in patients with RA and the impact of BMI on the efficacy and safety of filgotinib.

METHODS

FINCH 1-3 were randomized, double-blind, active- or placebo-controlled phase 3 trials of filgotinib 100 and 200 mg in patients with RA (N = 3452). BMI assessments included the mean change from baseline in BMI and the proportion of patients whose BMI increased by incremental thresholds. Efficacy measures included American College of Rheumatology (ACR) 20/50/70 response and low disease activity/remission according to Disease Activity Score 28 using C-reactive protein. The exposure-adjusted incident rate (EAIR) of adverse events (AEs) was assessed by baseline BMI, using integrated data from the FINCH 1-4 and the phase 2 DARWIN 1-3 studies (total filgotinib exposure = 8085 patient-years).

RESULTS

Mean change from baseline in BMI over time was similar across treatment arms. In most patients, BMI increased by ≤ 1 or 2 kg/m2 at both weeks 12 and 24, regardless of treatment group or baseline BMI; few patients had increases of ≥ 4 kg/m2. For most efficacy measures, filgotinib 200 mg was more efficacious than filgotinib 100 mg or active comparators or placebo across BMI subgroups. For the higher filgotinib dose, the EAIR of serious treatment-emergent AEs, venous thrombotic and embolic events, and major adverse cardiovascular events increased with increasing BMI.

CONCLUSIONS

Filgotinib did not lead to substantial changes in BMI, and BMI did not appear to affect the efficacy of filgotinib.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT02889796, NCT02873936, NCT02886728, NCT03025308, NCT01888874, NCT01894516, NCT02065700.

Real-world treatment persistence in patients with rheumatoid arthritis initiating DMARDs in Germany-a health insurance claims data analysis

OBJECTIVE

To investigate treatment patterns in patients with rheumatoid arthritis (RA) in Germany who had previously received conventional synthetic (cs) or biologic (b) disease-modifying antirheumatic drugs (DMARDs).

METHODS

Patients with RA who initiated treatment with a csDMARD, bDMARD, or Janus kinase (JAK) inhibitor between 2017 and 2018 and who had previously received csDMARD or bDMARD therapy were retrospectively selected from the Institute for Applied Health Research Berlin GmbH (InGef). Time on treatment and discontinuation risk were assessed using the Kaplan-Meier method. Cox regression identified variables associated with an increased discontinuation risk.

RESULTS

A total of 990 patients had received prior csDMARD therapy; 375 had received prior bDMARD therapy. Tumor necrosis factor (TNF)-α inhibitors and JAK inhibitors were the most commonly prescribed DMARD class in those previously treated with a csDMARD or bDMARD, respectively. In both cohorts, more patients received DMARD monotherapy than combination therapy. In the prior csDMARD cohort, median time on treatment was 276, 252, and 148 days with JAK inhibitors, TNF‑α inhibitors, and csDMARDs, respectively, and those treated with JAK or TNF‑α inhibitors were less likely to discontinue treatment than those on csDMARDs (log-rank test p-value < 0.01 for both comparisons); no significant differences were found within the prior bDMARD cohort.

CONCLUSION

This is among the first detailed analyses of RA treatment patterns in a real-world setting in Germany since the introduction of JAK inhibitors. TNF‑α inhibitors were the most commonly prescribed DMARD after failure of an initial csDMARD, while JAK inhibitors were the most common among patients previously treated with a bDMARD. In both groups, monotherapy with bDMARD or targeted synthetic DMARD was common. In the prior csDMARD cohort, treatment duration was significantly longer with JAK or TNF‑α inhibitors than with csDMARDs.

Persistence with Biologic Treatment in Patients with Inflammatory Bowel Disease: A German Claims Data Analysis

OBJECTIVES

This study aimed to assess the real-world rates of treatment discontinuation and switching of biologic therapies in patients with inflammatory bowel disease (IBD).

METHODS

A retrospective claims data analysis on all continuously insured adult IBD patients with initiation of a biologic therapy was conducted. Observation started with the date of the first prescription of index tumor necrosis factor α-inhibitors (anti-TNFα) or vedolizumab (VDZ) therapy and lasted 12 months. Non-persistence was assumed in case of a switch to another biologic or a treatment gap of >90 days.

RESULTS

We included 1,248 IBD biologic treatment starters (502 adalimumab, 77 golimumab, 441 infliximab, 228 VDZ); 837/411 were biologic-naïve (bio-naïve)/ biologic-experienced (bio-experienced). Mean age of bio-naïve/bio-experienced anti-TNFα patients was 39.2/38.1 years (54.9%/56.7% female) and 42.6/37.8 years for VDZ patients (56.3%/54.9% female). Seven hundred and seventy-two patients (61.9%) were persistent with their index biologic therapy after 12 months (61.9%/61.8% bio-naïve/bio-experienced). Percentage of persistent patients was 69.7% for VDZ (65.6%/71.3%) and 60.1% for anti-TNFα (61.4%/55.5%). VDZ was associated with later non-persistence in a multivariable Cox regression analysis (hazard ratio 0.675; p = 0.003) compared to anti-TNFα.

CONCLUSIONS

Only 60-70% of IBD -patients are still persistent with their biologic therapy after 12 months. VDZ therapy is associated with a higher persistence than anti-TNFα therapy in this analysis.

Real-world biologic treatment and associated cost in patients with inflammatory bowel disease

OBJECTIVES

 This study aimed to describe biologic treatment of German inflammatory bowel disease (IBD) patients, including biologics' dosage, health care resource use, and treatment-associated cost.

METHODS

 In this retrospective claims data analysis, all continuously insured adult IBD patients (Crohn's disease [CD] or ulcerative colitis [UC]) who started a new therapy with an anti-tumor necrosis factor alpha (anti-TNF-α) or vedolizumab (VDZ) were included. Observation started with the date of the first prescription of index biologic therapy and lasted 12 months.

RESULTS

 In the database, 1248 out of 57 296 IBD patients started a biologic treatment of interest (1020 anti-TNF-α, 228 VDZ), and 837 patients were bio-naïve (773 anti-TNF-α, 64 VDZ). The mean age of bio-naïve/bio-experienced anti-TNF-α patients was 39.2/38.1 years (54.9 %/56.7 % female) and 42.6/37.8 years for VDZ patients (56.3 %/54.9 % female). The proportion of patients receiving a maintenance dosage > 150 % compared to SmPC was 15.1 % for Adalimumab, 5.2-39.0 % for Golimumab, 14.7-34.5 % for Infliximab, and 19.7 % for VDZ patients. During the maintenance phase, up to 58.8 % of patients received at least 1 prescription of any CS, and 41.7 %/47.1 % (anti-TNF-α/VDZ) were treated in a hospital due to IBD. The mean IBD-related direct health care cost per patient year was € 30 246 (anti-TNF-α)/ € 28 227 (VDZ) for bio-naïve patients (p = 0.288) and € 34 136 (anti-TNF-α)/ € 32 112 (VDZ) for bio-experienced patients (p = 0.011).

CONCLUSIONS

 A substantial percentage of patients receive a high biologic dosage in the maintenance phase. Despite biologic therapy, 30-40 % receive a CS therapy and/or experience at least 1 IBD-associated hospitalization within a year, possibly indicating a remaining disease activity.

Flupirtine-induced liver injury--seven cases from the Berlin Case-control Surveillance Study and review of the German spontaneous adverse drug reaction reporting database

PURPOSE

The hepatotoxic potential of the analgesic flupirtine has attracted increased attention over the past years. Recently, risk minimisation measures such as maximum treatment duration of 2 weeks have been requested by the European Medicines Agency (EMA). This study was conducted to further elucidate the clinical pattern of flupirtine-induced liver injury (FILI).

METHODS

Seven FILI patients were ascertained in all Berlin hospitals in the Berlin Case-control Surveillance Study (FAKOS) between 2002 and 2011. Furthermore, we reviewed the severe cases of flupirtine-associated hepatotoxicity included in the adverse drug reaction database of the Federal Institute for Drugs and Medical Devices (BfArM) in Germany from between 1991 and 2012.

RESULTS

All seven FILI patients of FAKOS were hospitalised. Six of them were female, mean age was 58 [corrected] years, and the most common symptoms were fatigue and jaundice. Three patients developed acute liver failure (ALF). Discontinuation of flupirtine invariably led to clinical and laboratory improvement. Review of the BfArM cases (n = 248) showed female sex predominance and high prevalence of jaundice and ALF. Time to onset of symptoms was less than 2 weeks in 9 % of the patients with respective data.

CONCLUSIONS

Our results corroborate previous findings on FILI's clinical pattern and on its potentially severe course. Although the hepatotoxic risk might be higher after the first 2 weeks of treatment, earlier onset of severe FILI cannot be ruled out. Postauthorisation safety studies are needed to evaluate EMA's risk minimisation measures and to quantify flupirtine's risk according to its duration of use.

A natural fiber complex reduces body weight in the overweight and obese: a double-blind, randomized, placebo-controlled study

OBJECTIVE

A proprietary natural fiber complex (Litramine IQP G-002AS) derived from Opuntia ficus-indica, and standardized on lipophilic activity, was previously shown in preclinical and human studies to reduce dietary fat absorption through gastrointestinal (GI) fat binding. Here, we investigated the efficacy and safety of IQP G-002AS in body weight reduction.

DESIGN AND METHODS

One hundred twenty-five overweight and obese adults participated in the study. Subjects were advised on physical activity, and received nutritional counseling, including hypocaloric diet plans (30% energy from fat and 500 kcal deficit/day). After a 2-week placebo run-in phase, subjects were randomized to receive either 3 g/day of IQP G-002AS (IQ) or a placebo. The primary endpoint was change in body weight from baseline; secondary endpoints included additional obesity measures and safety parameters.

RESULTS

One hundred twenty-three subjects completed the 12-week treatment phase (intention-to-treat (ITT) population: 30 male and 93 female; mean BMI: 29.6 ± 2.8 kg/m(2) and age: 45.4 ± 11.3 years). The mean body weight change from baseline was 3.8 ± 1.8 kg in IQ vs. 1.4 ± 2.6 kg in placebo (P < 0.001). More IQ subjects lost at least 5% of their initial body weight compared to placebo (P = 0.027). Compared with placebo, IQ also showed significantly greater reduction in BMI, body fat composition, and waist circumference. IQ was well tolerated with no adverse reactions reported.

CONCLUSIONS

These results suggest that the natural fiber complex Litramine IQP G-002AS is effective in promoting weight loss.

S3 - Guidelines on the treatment of psoriasis vulgaris (English version). Update

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1.5% to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, surveys have shown that patients still do not received optimal treatments. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologi sche Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) have initiated a project to develop evidence-based guidelines for the management of psoriasis. They were first published in 2006 and updated in 2011. The Guidelines focus on induction therapy in cases of mild, moderate and severe plaque-type psoriasis in adults including systemic therapy, UV therapy and topical therapies. The therapeutic recommendations were developed based on the results of a systematic literature search and were finalized during a consensus meeting using structured consensus methods (nominal group process).

The extracellular regulated kinase-1 (ERK1) controls regulated alpha-secretase-mediated processing, promoter transactivation, and mRNA levels of the cellular prion protein

The α-secretases A disintegrin and metalloprotease 10 (ADAM10) and ADAM17 trigger constitutive and regulated processing of the cellular prion protein (PrP(c)) yielding N1 fragment. The latter depends on protein kinase C (PKC)-coupled M1/M3 muscarinic receptor activation and subsequent phosphorylation of ADAM17 on its intracytoplasmic threonine 735. Here we show that regulated PrP(c) processing and ADAM17 phosphorylation and activation are controlled by the extracellular-regulated kinase-1/MAP-ERK kinase (ERK1/MEK) cascade. Thus, reductions of ERK1 or MEK activities by dominant-negative analogs, pharmacological inhibition, or genetic ablation all impair N1 secretion, whereas constitutively active proteins increase N1 recovery in the conditioned medium. Interestingly, we also observed an ERK1-mediated enhanced expression of PrP(c). We demonstrate that the ERK1-associated increase in PrP(c) promoter transactivation and mRNA levels involve transcription factor AP-1 as a downstream effector. Altogether, our data identify ERK1 as an important regulator of PrP(c) cellular homeostasis and indicate that this kinase exerts a dual control of PrP(c) levels through transcriptional and post-transcriptional mechanisms.

Short-term treatment with a beta-blocker with vasodilative capacities improves intrarenal endothelial function in experimental renal failure

AIMS

In patients with renal disease the cardiovascular risk is greatly increased, and endothelial dysfunction is assumed to play a pivotal role in this process. Therefore we compared treatment effects of a beta-blocker with additional vasodilatory capacities (nebivolol) and a beta-blocker lacking these actions (metoprolol) on intrarenal and coronary vascular function in a rat model of renal failure with hypertension.

MAIN METHODS

Renal failure was induced by 5/6-nephrectomy (Nx) and analyzed after 4 weeks in Wistar rats. Untreated Nx, Nx/nebivolol 6 mg/d (Nx-Nebi); Nx/metoprolol 60 mg/d (Nx-Meto) and sham-operated (Sham) animals were studied. Isolated small renal and coronary arteries were investigated for endothelium-dependent relaxation to acetylcholine (ACh) and for the contribution of the endothelial mediators NO and endothelium-derived hyperpolarizing factor (EDHF).

KEY FINDINGS

Systolic blood pressure (SBP) was significantly increased in Nx, Nx-Nebi, and Nx-Meto (168+/-5, 153+/-3, and 162+/-6 mmHg) compared to Sham (138+/-3 mmHg, p<0.05, respectively). The increase in albuminuria of Nx (120-fold vs. Sham, p<0.0001) was almost (-85%) normalized by nebivolol compared to Sham (p<0.05), whereas metoprolol induced no significant effect. Renal arteries showed significantly increased Ach-relaxation in Nx and Nx-Nebi (Emax 86+/-4% and 76+/-7%, p<0.05) due to an increase in EDHF-mediated dilation (Emax_EDHF 78+/-7% and 73+/-6%) compared to Sham (Emax 54+/-4% and Emax_EDHF 44+/-6%) and Nx-Meto (Emax 42+/-12% and Emax_EDHF 18+/-5%). ACh-relaxation in coronary arteries was similar between groups but the contribution of NO (relative to EDHF) was strongly increased by nebivolol.

SIGNIFICANCE

The present findings offer an explanation of the nephroprotective effect of intrarenal endothelial function in renal failure.

Evidence-based (S3) guidelines for the treatment of psoriasis vulgaris

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1 to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, patient surveys have revealed lack of satisfaction with the efficacy of available treatments and a high rate of non-compliance. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologische Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) initiated a project to develop evidence-based guidelines for the management of psoriasis. These resulting Guidelines focus on induction therapy in cases of mild, moderate, and severe plaquetype psoriasis in adults. The Guidelines include evidence-based evaluation of the efficacy of all currently available therapeutic options in Germany. In addition, they offer detailed information on how best to administer the various treatments and give information on contraindications, adverse drug reactions, and drug interactions as well as estimates of practicability and cost. The Guidelines were developed following the recommendations of the Arbeitsgemeinschaft wissenschaftlicher medizinischer Fachgesellschaften (AWMF). The therapeutic recommendations were developed by an expert group and finalized during interdisciplinary consensus conferences.

German evidence-based guidelines for the treatment of Psoriasis vulgaris (short version)

Psoriasis vulgaris is a common and chronic inflammatory skin disease which has the potential to significantly reduce the quality of life in severely affected patients. The incidence of psoriasis in Western industrialized countries ranges from 1.5 to 2%. Despite the large variety of treatment options available, patient surveys have revealed insufficient satisfaction with the efficacy of available treatments and a high rate of medication non-compliance. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologische Gesellschaft and the Berufsverband Deutscher Dermatologen (BVDD) have initiated a project to develop evidence-based guidelines for the management of psoriasis. The guidelines focus on induction therapy in cases of mild, moderate, and severe plaque-type psoriasis in adults. The short version of the guidelines reported here consist of a series of therapeutic recommendations that are based on a systematic literature search and subsequent discussion with experts in the field; they have been approved by a team of dermatology experts. In addition to the therapeutic recommendations provided in this short version, the full version of the guidelines includes information on contraindications, adverse events, drug interactions, practicality, and costs as well as detailed information on how best to apply the treatments described (for full version, please see Nast et al., JDDG, Suppl 2:S1-S126, 2006; or http://www.psoriasis-leitlinie.de ).

Genomic organisation of the mouse gene encoding endothelin-converting enzyme-1 (ECE-1) and mRNA expression of ECE-1 isoforms in murine tissues

Mouse knockout-models have previously revealed important biological functions of endothelin-converting enzyme-1 (ECE-1) in normal cardiac and craniofacial development. Since human ECE-1 is expressed in various isoforms, termed a, b, c, and d, expression of which is controlled by alternative promoters, we postulated that corresponding isoforms may also be transcribed from the murine Ece1 gene. By comparative sequence analysis using exon-specific sequences of human and rat ECE-1 we have resolved the complete exon-intron structure of the murine Ece1 locus on chromosome 4. The murine Ece1 gene comprises 23 exons distributed over 100 kb of genomic DNA and was found to be structurally highly conserved when compared to the human ECE1 gene. As with the human gene, the exons containing isoform-specific sequences were localised in the 5' terminal region of the murine Ece1 gene. Using specific sense primers, isoform-specific expression of murine ECE-1 mRNA in various mouse tissues was confirmed by RT-PCR. Using real-time PCR we demonstrated that ECE-1c was the most abundantly expressed isoform in most tissues, except for heart and aorta displaying a more even isoform distribution. We detected an additional isoform-specific exon, designated c2, which was apparently constitutively spliced and expressed only as minor fraction of ECE-1c transcripts. Our results provide evidence of structural conservation of mammalian genes encoding ECE-1 and will facilitate a more refined analysis of ECE-1 mRNA expression in the mouse model organism.

Inverse regulation of preproendothelin-1 and endothelin-converting enzyme-1beta genes in cardiac cells by mechanical load

Mechanical stretch and para- and/or autocrine factors, including endothelin-1, induce hypertrophy of cardiac myocytes and proliferation of fibroblasts. To investigate the effect of mechanical load on endothelin-1 production and endothelin system gene expression in neonatal rat ventricular myocytes and fibroblasts, we exposed cells to cyclic mechanical stretch in vitro (0.5 Hz, 10-25% elongation, from 1 min to 24 h). Endothelin-1 peptide levels were measured from culture media of myocytes and fibroblasts and human umbilical vein endothelial cells (positive control) by specific radioimmunoassay. Preproendothelin-1 promoter activity was measured via transfection of reporter plasmids and mRNA levels with Northern blot analysis or quantitative RT-PCR. Activity of extracellular signal-regulated kinase was quantified with specific kinase assay. We found that stretching of myocytes activated preproendothelin-1 gene expression, including promoter activation, transient mRNA level increases, and augmented endothelin-1 secretion. In contrast, preproendothelin-1 gene expression was inhibited in stretched fibroblasts. Endothelin-converting enzyme-1beta mRNA levels elevated in stretched fibroblasts but decreased in stretched myocytes. Endothelin receptor type A mRNA levels declined in stretched myocytes, whereas levels were below detection in fibroblasts. Stretch activated extracellular signal-regulated kinase in myocytes, and when the kinase activity was pharmacologically inhibited, the preproendothelin-1 induction was suppressed. Transient overexpression of mitogen-activated ERK-activating kinase-1 induced preproendothelin-1 promoter in myocytes. In summary, mechanical stretch distinctly regulates endothelin system gene expression in cardiac myocytes and fibroblasts. The inhibition of the endothelin system may affect cardiac mechanotransduction and therefore provides an approach in treatment of load-induced cardiac pathology.

Differential regulation of in vivo angiogenesis by angiotensin II receptors

Angiotensin II (ANG II), a key regulator of blood pressure and body fluid homeostasis, exerts mitogenic effects on endothelial cells. We therefore hypothesized that ANG II could be a mediator between homeostatic changes within the vascular perfusion bed and growth factor-driven angiogenesis. In the present study, we applied the alginate implant angiogenesis model in mice with normal ANG II levels, elevated ANG II levels by transgenic overexpression of angiotensinogen (AOGEN), or in AT2 receptor-deficient mice. We demonstrate that a decrease in the amount of circulating ANG II by the angiotensin-converting enzyme (ACE) inhibitor enalapril or the AT1 receptor antagonist losartan induced a stimulation of in vivo angiogenesis implying an inhibitory function of ANG II through the AT1 receptor. However, the strong increase of angiogenesis in AOGEN-transgenic mice compared with mice with normal ANG II levels suggests additional stimulatory activity. We showed that the ANG II-induced stimulation of angiogenesis is linked to the AT2 receptor as an impaired induction of angiogenesis was obtained in AT2 receptor knockout mice. These findings provide the first evidence that the AT2 receptor mediates a stimulation of in vivo angiogenesis and indicate that ANG II is a humoral regulator of peripheral angiogenesis involving two receptor subtypes with opposing actions.

Regulation of the major isoform of human endothelin-converting enzyme-1 by a strong housekeeping promoter modulated by polymorphic microsatellites

BACKGROUND

Human endothelin-converting enzyme (ECE)-1, the key enzyme in endothelin biosynthesis, shows broad cell and tissue expression within the cardiovascular system. Expression of ECE-1c, which represents the major ECE-1 isoform, is directed by an alternative promoter, but the mechanisms of ECE-1c promoter regulation are largely unknown. As ECE-1c transcription is initiated from several start sites, we hypothesized that the ECE-1c promoter functions as a housekeeping promoter.

OBJECTIVE

To investigate the putative housekeeping function of the ECE-1c promoter in vascular endothelial cells, which represent a main site of its expression.

RESULTS

Using promoter reporter assays, gel shift and supershift assays, we have demonstrated, in human endothelial EA.hy926 cells, functionality of cis-acting elements for binding of the CAAT-box binding protein NF-YB, GATA-2) E2F-2, and a GC-box binding factor, which are spatially associated with transcriptional start sites of ECE-1c. In the more upstream promoter region we have identified three highly polymorphic dinucleotide repeats, 5'-(CA)n, (CG)n and 3'-(CA)n, which strongly affected promoter function in endothelial EA.hy926 cells (2.7-fold activation comparing the most active to the least active allele) and, in a similar manner, in human neuronal KELLY cells. Finally, by in-vitro methylation, we were able to achieve strong suppression of the ECE-1c promoter activity in endothelial cells.

CONCLUSION

Our results provide a molecular explanation for constitutive expression of ECE-1c mRNA. Modulation by genetic and epigenetic mechanisms as revealed in our study may account for interindividual variation of the constitutive endothelin system activity in humans and thus influence individual predisposition to cardiovascular disease.

Blockade of the intermediate-conductance calcium-activated potassium channel as a new therapeutic strategy for restenosis

BACKGROUND

Angioplasty stimulates proliferation and migration of vascular smooth muscle cells (VSMC), leading to neointimal thickening and vascular restenosis. In a rat model of balloon catheter injury (BCI), we investigated whether alterations in expression of Ca2+-activated K+ channels (KCa) contribute to intimal hyperplasia and vascular restenosis.

METHODS AND RESULTS

Function and expression of KCa in mature medial and neointimal VSMC were characterized in situ by combined single-cell RT-PCR and patch-clamp analysis. Mature medial VSMC exclusively expressed large-conductance KCa (BKCa) channels. Two weeks after BCI, expression of BKCa was significantly reduced in neointimal VSMC, whereas expression of intermediate-conductance KCa (IKCa1) channels was upregulated. In the aortic VSMC cell line, A7r5 epidermal growth factor (EGF) induced IKCa1 upregulation and EGF-stimulated proliferation was suppressed by the selective IKCa1 blocker TRAM-34. Daily in vivo administration of TRAM-34 to rats significantly reduced intimal hyperplasia by approximately 40% at 1, 2, and 6 weeks after BCI. Two weeks of treatment with the related compound clotrimazole was equally effective. Reduction of intimal hyperplasia was accompanied by decreased neointimal cell content, with no change in the rate of apoptosis or collagen content.

CONCLUSIONS

The switch toward IKCa1 expression may promote excessive neointimal VSMC proliferation. Blockade of IKCa1 could therefore represent a new therapeutic strategy to prevent restenosis after angioplasty.

Differential binding of transcription factor E2F-2 to the endothelin-converting enzyme-1b promoter affects blood pressure regulation

The endothelin-converting enzyme (ECE)-1 gene is a candidate for human blood pressure (BP) regulation and we report the identification of the new gene variants T-839G, C-338A, L75F, A677V and C+295T. Transient transfection of the reporter constructs containing the -338A allele showed an increase in promoter activity compared with the wild-type promoter. EMSA revealed the specific binding of E2F-2 to both ECE-1b promoter sequences, with the -338A allele being associated with an increased affinity to E2F-2 compared with -338C. The clinical relevance of this finding was analyzed in 704 hypertensive patients. In untreated hypertensive women, both the -338A and -839G alleles were significantly associated with ambulatory BP values. This study provides the first evidence of a link between the cell-cycle-associated E2F family and BP regulation via a component of the endothelin system.

Endothelin-1 mRNA and protein in vascular wall cells is increased by reactive oxygen species

A dysregulated metabolism of oxygen-derived free radicals, nitric oxide and endothelin-1(ET-1) in conditions such as hypercholesterolaemia or hypertension may promote the development of atherosclerosis. We therefore subjected cultured human umbilical vein endothelial cells and coronary artery smooth muscle cells to oxidative stress induced by xanthine oxidase or hydrogen peroxide and observed alterations in ET-1 metabolism. Incubation with oxygen-derived free radicals increased preproET-1 promoter activity, ET-1 mRNA synthesis and big ET-1 concentrations in both cell types. This interaction of oxidative stress and ET-1 expression may be relevant in atherogenic conditions such as hypercholesterolaemia and hypertension since our data indicate that oxidative stress further aggravates the injurious effects attributed to ET-1.

Endothelin-1 potently induces Leão's cortical spreading depression in vivo in the rat: a model for an endothelial trigger of migrainous aura?

According to the 'neuronal' theory, cortical spreading depression (CSD) is the pathophysiological correlate of migrainous aura. However, the 'vascular' theory has implicated altered vascular function in the induction of aura symptoms. The possibility of a vascular origin of aura symptoms is supported, e.g. by the clinical observation that cerebral angiography frequently provokes migrainous aura. This suggests that endothelial irritation may somehow initiate one of the pathways resulting in migrainous aura. Up to now, an endothelium-derived factor has never been shown to trigger CSD. Here, for the first time, we demonstrate and characterize the ability of the vasoconstrictor and astroglial/neuronal modulator endothelin-1 to trigger Leão's 'spreading depression of activity' in vivo in rats. At a concentration range between 10 nM and 1 microM, endothelin-1 induced changes characteristic of CSD with regard to the rate of propagation, steady (direct current) potential and extracellular K(+)-concentration. A spreading hyperaemia followed by oligaemia was observed similar to those in K(+)-induced CSD. Endothelin-1 did not provoke changes characteristic of a terminal depolarization. The mechanism by which endothelin-1 generated CSD involved the N-methyl-D-asparate receptor. Cerebral blood flow decreased slightly, but significantly, before endothelin-1 generated CSD. A vasodilator (NO*-donor) shifted the threshold for CSD induction to higher concentrations of endothelin-1. Endothelin-1, in contrast to K(+), did not induce CSD in rat brain slices suggesting indirectly that endothelin-1 may require intact perfusion to exert its effects. In conclusion, endothelin-1 was found in the experiment to be the most potent inducer of CSD currently known. We propose endothelin-1 as a possible candidate for the yet enigmatic link between endothelial irritation and migrainous aura.

Transcriptional mechanism of protein kinase C-induced isoform-specific expression of the gene for endothelin-converting enzyme-1 in human endothelial cells

Isoform-specific expression of endothelin-converting enzyme (ECE)-1, the major big endothelin-processing enzyme, is controlled by alternative promoters. Signaling pathways and transcriptional mechanisms of ECE-1 mRNA expression are largely unknown. To investigate ECE-1 isoform expression after protein kinase C (PKC) activation, we used phorbol 12-myristate 13-acetate (PMA) to stimulate primary cultured human umbilical vein endothelial cells and the related EA.hy926 cell line. ECE-1a mRNA was up-regulated (approximately 3-fold), whereas mRNA of alternative isoforms (b, c, and d) was unchanged, which was confirmed on the protein level. PMA effects on mRNA expression were suppressed by the PKC inhibitors H-7 and Calphostin C. Because increased ECE-1a expression was preceded by induction of the transcription factor Ets-1, we performed gel shift assays and demonstrated specific DNA/protein interactions involving the ETS binding motif GGAA. Luciferase reporter assays showed that PMA induced ECE-1a promoter activity about 2.5-fold in EA.hy926 cells. Similarly, coexpression of Ets-1 protein resulted in a dose-dependent increase in ECE-1a promoter activity (more than 8-fold). Using gel shift assays and mutation analysis, we identified two tandemly arranged Ets-1 binding sites (EBS) at -638 and -658, respectively, that are involved in transcriptional activation of the ECE-1a promoter by PMA or Ets-1. Moreover, we also found evidence for binding of a transcriptional repressor to EBS -638. The inhibitor of mitogen-activated protein kinase kinase, PD98059, inhibited PMA effects on ECE-1a mRNA expression and promoter activity, respectively. Our results provide the first detailed analysis of signaling pathways and transcriptional mechanisms involved in isoform-specific ECE-1 gene expression.

Big endothelin-1 and endothelin-1 plasma levels are correlated with the severity of primary pulmonary hypertension

STUDY OBJECTIVES

Primary pulmonary hypertension (PPH) is a rare disease of unknown etiology that is characterized by a poor prognosis. This study was undertaken to investigate possible correlations between endothelin (ET)-1 and big ET-1 plasma levels and the severity of PPH.

PATIENTS

Sixteen consecutive patients with PPH were included.

INTERVENTIONS

Hemodynamics of patients with PPH were measured by right-heart catheterization, and a 6-min walk test was performed.

MEASUREMENTS

Plasma levels of the biologically active peptide ET-1 and its precursor big ET-1 were determined in blood samples from the pulmonary artery, peripheral artery, and peripheral vein by radioimmunoassay.

RESULTS

A strong correlation was shown between pulmonary vascular resistance, mean pulmonary artery pressure, cardiac output, cardiac index, 6-min walk data, and elevated plasma levels of big ET-1 as well as mature ET-1 plasma levels at all sites of blood sampling (p < 0.01 and p < 0.05, respectively).

CONCLUSIONS

Levels of circulating ET-1 might become a prognostic marker for patients with PPH and serve as a tool for the selection of patients who may benefit from treatment with ET-receptor antagonists.

Characterization of polymorphic structure of cathepsin G gene: role in cardiovascular and cerebrovascular diseases

Cathepsin G (CTSG), a serine protease released from activated neutrophils, may cause platelet activation, leading to intravascular thrombosis, thus contributing to cardiovascular and cerebrovascular disease. Applying the candidate gene approach, we screened the 5'-flanking region and the entire coding region of the CTSG gene for genetic variation by using polymerase chain reaction/single-strand conformation polymorphism analysis from 96 patients at high risk for myocardial infarction (MI). We identified 4 polymorphisms in the 5'-flanking region (G-618C, G-315A, C-179T, and C-160T) and 1 polymorphism in the coding region (Asn125Ser) of the gene and genotyped the participants in the Etude Cas-Temoins sur l'Infarctus du Myocarde (ECTIM Study), a case-control study for MI, and in the Etude du Profil Génétique de l'Infarctus Cérébral (GENIC Study), a case-control study for brain infarction (BI), for all identified genetic variants. The potential in vitro functionality of the 4 variants in the 5'-flanking region was investigated with transient transfection analyses in U937 cells with different allelic promoter constructs by using a luciferase assay. Our in vitro analyses did not reveal any differences for the investigated allelic constructs with respect to promoter activity, and none of the polymorphisms in the 5'-flanking region was associated with the available phenotypes in either study. Allele and genotype distributions of all identified polymorphisms did not globally differ between cases and controls in the ECTIM Study. However, in patients from the ECTIM Study, the Ser125 allele was significantly associated with elevated plasma fibrinogen levels (P=0.006), but this effect was not seen in controls (case-control heterogeneity, P=0.04). There was a significant interaction between CTSG Asn125Ser and the beta-fibrinogen gene polymorphism G-455A on plasma fibrinogen levels (P=0.04). In the GENIC Study, the odds ratio for BI associated with CTSG Ser125 carrying was 1.82 (95% CI 1.16 to 2.84, P=0.008) in patients without a history of cardiovascular or cerebrovascular diseases. Our results indicate that the CTSG Ser125 allele is associated with plasma fibrinogen levels in MI patients from the ECTIM Study and with BI in the GENIC Study. Further studies should be carried out to define the underlying mechanisms.

Functional characterization of the human prion protein promoter in neuronal and endothelial cells

Human prion diseases such as Creutzfeld-Jakob disease and kuru are of major medical and biological importance because of their fatal course, epidemic potential, and unique pathophysiology. Endogenous expression of the normal cellular prion protein (PrP(C)) is necessary for infection and prion replication. However, knowledge of human PrP(C) gene regulation is rudimentary. We therefore cloned1543 bp of the 5' untranslated and promoter region of the PrP gene. Using transient transfection assays, the full-length promoter and serial deletion mutants subcloned in a luciferase reporter vector were analyzed in neuronal (KELLY) and endothelial (EA.hy926) cell lines, which both express PrP(C) as shown by RT/PCR. Analysis of promoter constructs in KELLY cells indicated two activating regions at -131/-284 and -1303/-1543, relative to the 3'-terminal end of exon 1, and also two repressing elements at -254/-567 and -567/-909 in neuronal cells. In EA.hy926 cells, activating elements were identified at -131/-284 and -284/-567, and one repressing region was localized at -567/-909. In addition, transcriptional start sites were determined by 5'-RACE reaction and RNase protection assay, revealing one major transcriptional start site located at -47 (in KELLY cells), -53 (in human thalamus) and at about -55 (in EA.hy926 cells).

Impaired hyperpolarization in regenerated endothelium after balloon catheter injury

Ca(2+)-activated K(+) (K(Ca)) channels control endothelial Ca(2+) homeostasis and the formation of vasodilators. After angioplasty, dysfunction of the regenerated endothelium leads to abnormal vasoregulation. In this study, we tested the expression and function of K(Ca) channels in regenerated endothelium at 6 weeks after balloon catheter injury of rat carotid arteries (CAs) by using single-cell reverse transcription-polymerase chain reaction, patch-clamp techniques, and analysis of vasoreactivity. In single regenerated endothelial cells (ECs), the percentage of ECs expressing the K(Ca) genes, rSK3 (12+/-8%) and rIK1 (22+/-9%), was significantly lower compared with the percentage of native ECs expressing these genes (rSK3 58+/-8%, rIK1 64+/-10%). In patch-clamp experiments, K(Ca) currents and acetylcholine-induced hyperpolarization were markedly reduced in regenerated ECs (shift of membrane potential -6+/-3 mV) compared with those in native ECs (shift of membrane potential -21+/-5 mV). In pressure myograph experiments, acetylcholine-induced dilation was impaired in reendothelialized CAs compared with normal CAs. Intraluminal application of the K(Ca) blocker apamin and charybdotoxin inhibited dilation by 30% in normal CAs but was without effect in reendothelialized CAs. Intraluminal application of 1-ethyl-2-benzimidazolinone (100 micromol/L), an opener of K(Ca) channels, evoked dilation by 29% in normal CAs but had no effect in reendothelialized CAs. In conclusion, the impaired expression of K(Ca) channels in regenerated endothelium results in defective hyperpolarization and impaired dilation. Thus, the impaired K(Ca) channel function contributes to functional alterations of regenerated endothelium after angioplasty.

Transcriptional control of deformation-induced preproendothelin-1 gene expression in endothelial cells

Deformation-induced synthesis of endothelin-1 (ET-1) in endothelial cells exposed to high blood pressure may play an important role in vein graft disease and in restenosis following percutaneous transluminal angioplasty. Effective inhibitors of preproendothelin ET-1 (ppET-1) processing to ET-1 are not available, and blockade of ppET-1 expression may therefore emerge as an alternative therapeutic approach. To evaluate this, we investigated deformation-sensitive transcription factors controlling ppET-1 expression in both native (rabbit carotid artery and jugular vein) and cultured endothelial cells (EC; porcine aorta and human umbilical vein). Deformation of both native and cultured endothelial cells for 6 h resulted in a marked increase in ET-1 synthesis which was preceded by a transient (30-60 min) activation of transcription factors activator protein-1 (AP-1) and CCAAT/enhancer-binding protein (C/EBP) beta and/or delta. A decoy oligodeoxynucleotide directed against AP-1 inhibited deformation-induced ppET-1 expression in the rabbit jugular vein as well as in porcine aorta EC and human umbilical vein EC but not in the rabbit carotid artery. Subsequent reporter gene analyses with different rat ppET-1 promoter-luciferase constructs transiently transfected into porcine aorta EC identified a single AP-1 binding site at -110 to -100 bp as the primary response element for deformation-induced ppET-1 expression. Moreover, a C/EBP-specific decoy oligodeoxynucleotide abolished ppET-1 expression in the endothelium of the rabbit carotid artery, but not in the jugular vein where basal ET-1 synthesis was greatly enhanced instead. These findings suggest that the key transcription factors controlling deformation-induced ppET-1 expression in endothelial cells are blood vessel rather than species-specific. In humans, adjunct treatment with an AP-1-specific decoy oligodeoxynucleotide may prove be an interesting gene therapeutic option for the above cardiovascular interventions.

Increased matrix metalloproteinase 2 concentration and transcript expression in advanced colorectal carcinomas

Colorectal cancer is one of the most common malignant tumors and entails a relatively poor prognosis. Clinical outcome depends on the extent of local and metastatic tumor spread. Results of in vivo and in vitro studies suggest that the balance between matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases TIMPs) is altered in neoplasia, contributing to the invasive and metastatic properties of malignant tumors. We quantified tissue concentrations of MMP-2 and TIMP-2 in 65 malignant colorectal lesions and corresponding normal mucosa by enzyme-linked immunosorbent assay, western blotting, and in situ hybridization. In situ hybridization and western blot analyses demonstrated a clear increase in both stromal expression of MMP-2 transcripts and protein in primary carcinomas. The protein concentration of MMP-2 was higher in all tumor stages, except stage I tumors, than in normal mucosa and adenomas. MMP-2 concentrations were not related to tumor differentiation or to colonic versus rectal location. Surprisingly, the MMP-2 concentration was not increased in metastases. Interestingly, tissue concentrations and epithelial mRNA expression of TIMP-2 decreased significantly in primary colorectal cancer (UICC stages III and IV) but increased in metastases. Therefore an increased ratio of MMP-2 to TIMP-2 is strongly associated with advanced tumor stages, but a decreased ratio was observed in metastases. These findings suggest that the MMP-2:TIMP-2 ratio may prove useful as a marker of local invasion but not of metastasis in colorectal cancer.

Impaired Function and Expression of Endothelial Small Ca 2+ -Activated K Channels (SK3) in Reendothelialized Carotid Arteries After Balloon Catheter Injury (BCI)

P80

Ca 2+ -activated K channels (K Ca ) play an important role in endothelial function by controlling the electrochemical driving force for Ca 2+ influx and subsequent formation of vasoactive factors like NO and EDHF. An altered endothelial function have been suggested to be present in reendothelialized arteries after balloon catheter injury (BCI). We compared expression and function of endothelial rSK3 in reendothelialized carotid artery (CA) after BCI and not injured contralateral CA (CON) by using single-cell RT-PCR and patch-clamp (PC) techniques. Male Sprague-Dawley rats underwent BCI of the right CA. After 6 weeks, neointima formation and reendothelialization were confirmed by morphological analysis. Single endothelial cells (EC) were directly harvested from the luminal wall with the patch pipette. cDNA of rSK3 was amplified along with cDNA of endothelial nitric oxide synthase (rNOSIII), an EC marker. The percentage of rNOSIII + -samples was not different between CON (84% ± 10) and injured CA (84% ± 6). Expression of rSK3 was detected in 50% ± 10 of rNOSIII + -EC from CON. From injured CA, expression of rSK3 was detected in only 3% ± 3 of NOSIII + -EC (P<0.05). In whole-cell PC experiments in EC from CON, cell dialysis with Ca 2+ induced K currents, which were sensitive to apamin, a blocker of SK3. In contrast, in EC from injured CA, cell dialysis with Ca 2+ did not activate K currents. In current-clamp PC measurements of EC membrane potential (Vm) of CON, acetylcholine (ACh) induced a sustained and apamin-sensitive hyperpolarization from a resting Vm of -19 ± 5 mV to 40 ± 13 mV (ΔVm -19 ± 7 mV). In injured CA, an ACh-induced hyperpolarization was not observed (-22 ± 7 mV, ΔVm 0 ± 1 mV). Resting Vm (22 ± 6 mV) was not different. In conclusion, the deficient expression of K Ca in reendothelialized injured CA abolishes endothelial hyperpolarization in response to humoral stimulation. The defective hyperpolarization presumably leads to a decreased Ca 2+ influx and subsequent synthesis of vasoactive factors. This might indicate a diminished function of the newly formed endothelium in CA after BCI.

Cardiac endothelin system impairs left ventricular function in renin-dependent hypertension via decreased sarcoplasmic reticulum Ca(2+) uptake

BACKGROUND

We evaluated the role of the cardiac endothelin (ET) system in compensated hypertensive left ventricular (LV) hypertrophy (LVH) and after the transition toward LV dysfunction.

METHODS AND RESULTS

Hypertensive transgenic rats overexpressing the Ren2 gene (Ren2 rats) were investigated between the ages of 10 and 30 weeks (Ren2-10 and Ren2-30 groups, respectively) and compared with age-matched normotensive Sprague-Dawley (SD) rats (SD-10 and SD-30 groups, respectively). Systolic blood pressure and LV weight were elevated in both Ren2 groups compared with their age-matched SD control groups (P:<0.0001). In Ren2-30 rats, LV end-diastolic pressure increased and -dP/dt(max) decreased compared with the values in SD-30 and Ren2-10 rats (P:<0.05). This was paralleled by an activation of LV mRNA expression of preproET-1 and ET-converting enzyme-1 and ET subtype A (ETA) receptor binding in Ren2-30 compared with Ren2-10 rats (P:<0.001). Cardiac fibrosis was increased and sarcoplasmic reticulum (SR) Ca(2+) reuptake was reduced in Ren2-30 compared with SD-30 and Ren2-10 rats (P:<0.05). Treatment of Ren2 rats with the selective ETA receptor antagonist Lu135252 between 10 and 30 weeks of age did not lower systolic blood pressure, heart weight, or cardiac fibrosis but completely prevented the deterioration of LV end-diastolic pressure and abolished alterations in -dP/dt(max) and SR Ca(2+) reuptake compared with no treatment in Ren2-30 and SD-30 rats (P:<0.05).

CONCLUSIONS

Activation of the cardiac ET system accounts at least in part for the LV dysfunction that gradually develops in LVH. The protective effect of ETA antagonism can be attributed to the improvement of diastolic LV function that is due to normalization of impaired SR Ca(2+) uptake.

Oxidative stress increases synthesis of big endothelin-1 by activation of the endothelin-1 promoter

Modulation of the biosynthesis of the vasoconstrictor peptide endothelin-1 by oxygen-derived free radicals generated by xanthine oxidase or hydrogen peroxide was studied in cultured endothelial cells. Endothelin-1 metabolism was investigated at the level of endothelin-1 promoter, preproendothelin-1 mRNA and intracellular big endothelin-1. Endothelin-1 mRNA, as characterized by Northern blotting, was increased both time- and dose-dependently by xanthine oxidase to up to 500% above baseline. Analysis of endothelin-1 promoter activity using a construct containing 1329 bp of the endothelin-1 promoter revealed that promoter activity was increased up to eight-fold by incubation with xanthine oxidase. Specificity was ascertained by co-incubation with superoxide dismutase and catalase leading to inhibition of the effect of xanthine oxidase. A significant contribution of nitric oxide was ruled out, since NOS III-mRNA transcription remained unchanged and l -NAME did not significantly alter endothelin-1 promoter activity. Synthesis of intracellular big endothelin-1 protein was increased dose-dependently by xanthine oxidase. Our results indicate that oxidative stress leads to increased endothelial synthesis of big endothelin-1, which is a previously unknown mechanism and may help to understand the detrimental association of increased oxidative stress and elevated endothelin-1 levels in pathophysiological conditions promoting atherosclerosis.

Influence of sustained mechanical stress on Egr-1 mRNA expression in cultured human endothelial cells

Restenosis after initially successful balloon angioplasty of coronary artery stenosis remains a major problem in clinical cardiology. Previous studies have identified pathogenetic factors which trigger cell proliferation and vascular remodeling ultimately leading to restenosis. Since there is evidence that endothelial cells adjacent to the angioplasty wound area synthesize factors which may initiate this process, we investigated the effects of mechanical stimulation on endothelial gene expression in vitro and focussed on the influence of sustained mechanical stress on expression of immediate early genes which have previously been shown to be induced in the vascular wall in vivo. Primary cultured human umbilical vein endothelial cells (HUVEC) and the human endothelial cell line EA.hy 926 were plated on collagen-coated silicone membranes and subjected to constant longitudinal stress of approximately 20% for 10 min to 6 h. Total RNA was isolated and the expression of the immediate early genes c-Fos and Egr-1 was studied by Northern blot analysis. We found a rapid upregulation c-Fos and Egr-1 mRNA which started at 10 min and reached its maxima at 30 min. HUVEC lost most of their stretch response after the third passage whereas immediate early gene expression was constantly in EA.hy 926 cells. Using specific inhibitors we investigated the contribution of several signal transduction pathways to stretch-activated Egr-1 mRNA expression. We found significant suppression of stretch-induced Egr-1 mRNA expression by protein kinase C (PKC) inhibition (p < 0.05) and by calcium depletion (EA.hy 926, p < 0.05; HUVEC, p = 0.063). No effect on stretch-activated Egr-1 mRNA expression was detected by inhibition of protein kinase A, blockade of stretch-activated cation channels or inhibition of microtubule synthesis. We conclude that sustained mechanical strain induces Egr-1 mRNA expression by PKC- and calcium-dependent mechanisms.

Characterization of the c-specific promoter of the gene encoding human endothelin-converting enzyme-1 (ECE-1)

Human ECE-1 is expressed in four isoforms with different tissue distribution and its mRNA and protein levels are altered under certain pathophysiological conditions. To investigate the transcriptional regulation of ECE-1, we studied the regulatory region of ECE-1c, the major ECE-1 isoform. A genomic clone comprising the complete human ECE-1 gene including the putative ECE-1c-specific promoter was obtained. Up to 968 bp upstream of the putative c-specific translation initiation start codon and several serial deletion mutants were subcloned into a reporter vector and transfected into endothelial (BAEC, EA.hy926, ECV304) and epithelial (MDA MB435S, MCF7) cells, showing very strong promoter activity in comparison to the SV40 promoter and to the previously described ECE-1a and 1b promoters. Transfection of serial deletion mutants indicated two positive regulatory regions within the promoter (-142/-240 and -240/490) likely involved in binding GATA and ETS transcription factors. RNase protection assay (RPA) and 5'-RACE revealed multiple transcriptional start sites located at about -110, -140 and -350 bp. Site-directed mutagenesis demonstrated a crucial role for the E2F cis-element for basal ECE-1c promoter activity. Additionally, we found a correlation between isoform-specific ECE-1 mRNA levels and corresponding ECE-1a, 1b, 1c promoter activities.

32/67-kD laminin receptor expression in human colonic neoplasia: elevated transcript levels correlate with the degree of epithelial dysplasia

OBJECTIVE

The 32/67-kD laminin receptor is thought to be involved in tumor cell migration and metastasis formation, and enhanced expression was observed in human colorectal carcinoma. Our objective was to investigate further the expression of the 32/67-kD laminin receptor RNA in human colonic carcinogenesis.

METHODS

We obtained sections of human colonic tissues in various stages of malignant transformation and analyzed them by in situ hybridization.

RESULTS

Normal colonic mucosa displayed a gradient between crypt base and surface epithelium with lowest receptor RNA levels in superficial epithelial cells. Increased laminin receptor RNA expression was observed in epithelial cells of adenomas with positive correlation between transcript levels and the degree of epithelial dysplasia. At variance with published results, we did not observe significant differences in 32/67-kD laminin receptor transcripts between adenomas with high-grade dysplasia and invasive adenocarcinoma. However, adenocarcinoma metastases displayed significantly higher laminin receptor RNA levels than high-grade adenomas and primary carcinomas.

CONCLUSIONS

We propose a two-step mechanism which controls first, upregulation of laminin receptor RNA before the acquisition of an invasive phenotype in dysplastic epithelial cells, and second, a further upregulation in metastatic cells during the adenoma-carcinoma sequence of the colon.

Cloning and functional characterization of the bovine endothelin-converting enzyme-1a promoter

Endothelin-converting enzyme-1 (ECE-1) mRNA is expressed in three isoforms, termed a, b, and c, originating from alternative promoters. In cultured bovine aortic endothelial cells, we detected mRNA isoform expression of ECE-1a and ECE-1b/c, respectively. Investigating transcriptional mechanisms of bovine endothelial ECE-1a expression in more detail, we identified multiple transcription start sites localized 120-415 nucleotides upstream from the presumptive translation start codon by RNase protection assay and 5' RACE. Using luciferase reporter gene assays we found that 1.4 kb of the 5' untranslated region showed strong promoter activity in endothelial cells. Sequence analysis revealed 71% overall homology of the bovine ECE-1a promoter with its human homologue. The proximal 680 base pair promoter region was shown to contain cis elements that are sufficient for basal and serum-induced transcriptional activation.

The cardiac endothelin system in established pressure overload left ventricular hypertrophy

In normal hearts, endothelin-1 (ET-1) has been shown to initiate myocyte growth and to modulate cardiac function. However, regulation of the various components of the system and the functional effects of ET-1 in established left ventricular hypertrophy (LVH) are less clear. We thus studied ET-1, ET(A) receptor, and endothelin converting enzyme (ECE-1) mRNA regulation as well as the effects of ET-1 on coronary resistance, LV contractility and relaxation in hypertrophied rat hearts. Cardiac pressure overload, secondary to banding of the ascending aorta, resulted in a transient increase of cardiac ET-1 and ET(A) receptor mRNAs that reached a maximum at 2 days (+75% and +40%, respectively, P<0.05, each). ET-1 mRNA levels reached a second peak at 84 days of pressure overload (+60%, P<0.05), at the later time point in conjunction with elevated ECE-1 mRNA levels (+20%, P<0.05). The functional implications of ET-1 were examined in a study of isolated perfused hearts. Both hearts with established LVH and sham control hearts responded to ET-1 perfusion (10(-1)] to 10(-9) M) with an increase of coronary perfusion pressure (CPP; +85+/-15 and +75+/-8 mm Hg; P<0.001 each) and a slight decrease of LV systolic pressure (LVP; -12+/-9 and -9+/-7 mm Hg; P = NS). In contrast, ET-1 increased LV end-diastolic pressure (LVEDP) only in LVH hearts (+22+/-7 mm Hg, P<0.05 versus baseline and +20+/-7 mm Hg, P<0.05 versus sham). Direct stimulation of protein kinase C mimicked the effects of ET-1, whereas inhibition of this kinase or the Na+ -H+ exchanger blunted the effects of ET-1 on CPP, LVP, and LVEDP. Interestingly, coadministration of the vasodilator and the nitric oxide (NO) donor nitroglycerin not only prevented the increase of CPP and LVEDP, but also uncovered a slight positive inotropic effect of ET-1 in LVH hearts. Thus, the cardiac expression of ET-1, ET(A), and ECE-1 mRNAs displays a distinct pattern during early and advanced cardiac pressure overload. Furthermore, ET-1 mediates a slight depression of systolic, and a profound depression of diastolic, functional parameters in hearts with established LVH, effects that appear to be secondary to ET-1-related coronary vasoconstriction. The data suggest a functional role of the endothelin system in hearts with established pressure overload hypertrophy.