Regulation of melastatin, a TRP-related protein, through interaction with a cytoplasmic isoform

The TRP (transient receptor potential) superfamily includes a group of subfamilies of channel-like proteins mediating a multitude of physiological signaling processes. The TRP-melastatin (TRPM) subfamily includes the putative tumor suppressor melastatin (MLSN) and is a poorly characterized group of TRP-related proteins. Here, we describe the identification and characterization of an additional TRPM protein TRPM4. We reveal that TRPM4 and MLSN each mediate Ca(2+) entry when expressed in HEK293 cells. Furthermore, we demonstrate that a short form of MLSN (MLSN-S) interacts directly with and suppresses the activity of full-length MLSN (MLSN-L). This suppression seems to result from the inhibition of translocation of MLSN-L to the plasma membrane. We propose that control of translocation through interaction between MLSN-S and MLSN-L represents a mode for regulating ion channel activity.     

Hepatocellular carcinoma,a unique tumor with a lack of biomarkers

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Interestingly, the great majority of individuals affected by the tumor have underlying liver disease, therefore narrowing the population to be screened. Still, however, there is a clear lack of blood biomarkers, and surveillance in those at risk is performed by frequent imaging of the liver. A variety of multinational collaborations are currently invested in finding biomarkers for HCC based on liver-produced proteins. A new approach with assessment of peripheral proteins might be necessary for the successful early detection of this malignancy.     

Polyphosphate kinase 1, a conserved bacterial enzyme, in a eukaryote, Dictyostelium discoideum, with a role in cytokinesis

Polyphosphate kinase 1 (PPK1), the principal enzyme responsible for reversible synthesis of polyphosphate (poly P) from the terminal phosphate of ATP, is highly conserved in bacteria and archaea. Dictyostelium discoideum, a social slime mold, is one of a few eukaryotes known to possess a PPK1 homolog (DdPPK1). Compared with PPK1 of Escherichia coli, DdPPK1 contains the conserved residues for ATP binding and autophosphorylation, but has an N-terminal extension of 370 aa, lacking homology with any known protein. Polyphosphate or ATP promote oligomerization of the enzyme in vitro. The DdPPK1 products are heterogeneous in chain length and shorter than those of E. coli. The unique DdPPK1 N-terminal domain was shown to be necessary for its enzymatic activity, cellular localization, and physiological functions. Mutants of DdPPK1, as previously reported, are defective in development, sporulation, and predation, and as shown here, in late stages of cytokinesis and cell division.     

Sclerosing mesenteritis, a rare mesenteric disorder, in a patient with ulcerative colitis

A 60-year-old female who had been ill with ulcerative colitis for more than ten years presented with upper abdominal pain. A flare-up of ulcerative colitis was unlikely, because she did not report rectal bleeding, altered bowel habit, and changes of stool form. A poorly defined mass with mild tenderness was palpable in the upper abdomen, with increased levels of serum pancreatic enzymes, leading us to suspect pancreatic disease. Although CT scan revealed no abnormalities in the pancreas, a well-defined, heterogeneous soft tissue mass was found in the small bowel mesentery. Although several different diagnoses were considered, characteristic features on CT strongly supported diagnosis of sclerosing mesenteritis. The symptoms resolved quickly without specific treatment. The mesenteric lesion has never changed and no unfavorable events have yet occurred.     

Adrenomedullin, a new peptide, in patients with insulinoma

BACKGROUND: It has been demonstrated that adrenomedullin, a newly discovered peptide, affects the release of insulin from pancreatic islets cells, suggesting a role in the insulin-regulating system. OBJECTIVE: To investigate whether adrenomedullin secretion is modified in patients with insulin-secreting islet cell tumours. DESIGN: The study was performed in nine patients with surgically treated insulinoma. Circulating adrenomedullin was assayed using a specific radioimmunoassay and its localization and distribution in the tumour were determined by means of immunohistochemistry. RESULTS: Adrenomedullin concentrations were significantly greater in patients with insulinoma (6.6 +/- 3.2 fmol/ml) than in controls (2.1 +/- 1.1 fmol/ml). In six patients monitored before and after surgery, plasma adrenomedullin decreased from 6.3 +/- 2.9 fmol/ml to 3.0 +/- 1.6 fmol/ml. Immunoreactive adrenomedullin was localized exclusively in the tumours cells, whereas stroma, surrounding pancreas parenchyma and major ducts were negative for the peptide. CONCLUSIONS: Our findings indicate that circulating adrenomedullin is increased in insulinoma and that this increase is related to the neoplastic phenotype.     

Identification of a urate transporter,ABCG2, with a common functional polymorphism causing gout

Genome-wide association studies (GWAS) have successfully identified common single nucleotide polymorphisms (SNPs) associated with a wide variety of complex diseases, but do not address gene function or establish causality of disease-associated SNPs. We recently used GWAS to identify SNPs in a genomic region on chromosome 4 that associate with serum urate levels and gout, a consequence of elevated urate levels. Here we show using functional assays that human ATP-binding cassette, subfamily G, 2 (ABCG2), encoded by the ABCG2 gene contained in this region, is a hitherto unknown urate efflux transporter. We further show that native ABCG2 is located in the brush border membrane of kidney proximal tubule cells, where it mediates renal urate secretion. Introduction of the mutation Q141K encoded by the common SNP rs2231142 by site-directed mutagenesis resulted in 53% reduced urate transport rates compared to wild-type ABCG2 (P < 0.001). Data from a population-based study of 14,783 individuals support rs2231142 as the causal variant in the region and show highly significant associations with urate levels [whites: P = 10⁻³⁰, minor allele frequency (MAF) 0.11; blacks P = 10⁻⁴, MAF 0.03] and gout (adjusted odds ratio 1.68 per risk allele, both races). Our data indicate that at least 10% of all gout cases in whites are attributable to this causal variant. With approximately 3 million US individuals suffering from often insufficiently treated gout, ABCG2 represents an attractive drug target. Our study completes the chain of evidence from association to causation and supports the common disease-common variant hypothesis in the etiology of gout.     

Successful treatment of Erdheim-Chester disease, a non-Langerhans-cell histiocytosis, with interferon-alpha

Erdheim-Chester disease is a rare non-Langerhans histiocytosis with multisystem involvement. To date, there is no standard treatment for this disorder, and more than half of the patients succumb within 3 years. Because interferon-alpha promotes the terminal differentiation of histiocytes and dendritic cells, we hypothesized that this molecule would be a useful therapy for Erdheim-Chester disease. We therefore treated 3 patients with advanced disease with interferon-alpha at a starting dose of 3 to 6 x 10(6) units, which was later reduced, during maintenance, to 1 x 10(6) units subcutaneous 3 times per week. Marked improvement was noted in all patients, with substantial retro-orbital disease regression within 1 month. Improvement in bone lesions, pain, diabetes insipidus, and other manifestations was gradual over many months. Responses were durable (3+ to 4.5+ years). Our observations suggest that this well-tolerated therapy has a significant effect on the course and outcome of Erdheim-Chester disease.     

Effect of protracted treatment with rosiglitazone, a PPARgamma agonist, in patients with Cushing's disease

OBJECTIVE: Cushing's disease, hypercortisolism due to a pituitary ACTH-secreting tumour, is a highly morbid illness as yet without effective medical therapy. Recent studies have demonstrated that peroxisome proliferator-activated receptor gamma (PPARgamma) agonists effectively suppress ACTH secretion in a murine tumoral corticotroph cell line, but the few studies conducted so far in patients with ACTH-secreting pituitary adenomas have yielded variable results. DESIGN: Ten patients with Cushing's disease were treated with 4-16 mg rosiglitazone p.o. daily for 1-8 months (median 3 months) and plasma ACTH and cortisol, urinary free cortisol (UFC), as well as parameters of insulin sensitivity, were recorded. An acute challenge with 8 mg rosiglitazone for 2 days preceded long-term rosiglitazone administration. RESULTS: The acute challenge with rosiglitazone did not significantly modify plasma ACTH and cortisol levels. During protracted treatment with rosiglitazone, four patients showed a persistent reduction in UFC levels (up to 24% of pretreatment values), achieving normalization in three. In the others, UFC as well as plasma ACTH and cortisol decrements were inscribed within wide, random oscillations indicating that disease activity was substantially unchanged. Insulin sensitivity was ameliorated in most patients, without relation to ACTH or cortisol secretion. Untoward effects, such as weight gain, oedema and worsening of ecchymoses, were reported in several patients. CONCLUSIONS: Although effective in a subset of patients, protracted rosiglitazone administration did not consistently restrain ACTH and cortisol secretion in patients with Cushing's disease. Further investigations are needed to fully define the therapeutic potential of PPARgamma agonists in this disorder.     

Treatment of rheumatoid arthritis with anakinra, a recombinant human interleukin-1 receptor antagonist, in combination with methotrexate: results of a twenty-four-week, multicenter, randomized, double-blind, placebo-controlled trial

OBJECTIVE: To evaluate the efficacy and safety of anakinra in combination with methotrexate (MTX) in patients with active rheumatoid arthritis (RA). METHODS: Patients with moderate-to-severe active RA who were receiving MTX for 6 consecutive months, with stable doses for > or = 3 months (those with disease duration of >6 months but <12 years) were randomized into 6 groups: placebo or 0.04, 0.1, 0.4, 1.0, or 2.0 mg/kg of anakinra administered in a single, daily, subcutaneous injection. The primary efficacy end point was the proportion of subjects who met the American College of Rheumatology 20% improvement criteria (attained an ACR20 response) at week 12. RESULTS: A total of 419 patients were randomized in the study. Patient demographics and disease status were similar in the 6 treatment groups. The ACR20 responses at week 12 in the 5 active treatment plus MTX groups demonstrated a statistically significant (P = 0.001) dose-response relationship compared with the ACR20 response in the placebo plus MTX group. The ACR20 response rate in the anakinra 1.0-mg/kg (46%; P = 0.001) and 2.0-mg/kg (38%; P = 0.007) dose groups was significantly greater than that in the placebo group (19%). The ACR20 responses at 24 weeks were consistent with those at 12 weeks. Similar improvements in anakinra-treated subjects were noted in individual ACR components, erythrocyte sedimentation rate, onset of ACR20 response, sustainability of ACR20 response, and magnitude of ACR response. Anakinra was safe and well tolerated. Injection site reaction was the most frequently noted adverse event, and this led to premature study withdrawal in 7% (1.0-mg/kg group) to 10% (2.0-mg/kg group) of patients receiving higher doses. CONCLUSION: In patients with persistently active RA, the combination of anakinra and MTX was safe and well tolerated and provided significantly greater clinical benefit than MTX alone.     

In patients with COPD, treatment with a combination of formoterol and ipratropium is more effective than a combination of salbutamol and ipratropium : a 3-week, randomized, double-blind, within-patient, multicenter study

STUDY OBJECTIVES: To compare the efficacy of adding formoterol or salbutamol to regular ipratropium bromide treatment in COPD patients whose conditions were suboptimally controlled with ipratropium bromide alone. DESIGN: A randomized, double-blind, double-dummy, two-period, crossover clinical trial. SETTING: Twenty-four clinics and university medical centers in nine countries. PATIENTS: One hundred seventy-two patients with baseline FEV(1) < or = 65% predicted, with FEV(1) reversibility to salbutamol not exceeding the normal variability of the measurement, and symptomatic despite regular treatment with ipratropium bromide. INTERVENTIONS: Each patient received two treatments in random order: either inhaled formoterol dry powder, 12 microg bid, in addition to ipratropium bromide, 40 microg qid for 3 weeks, followed by salbutamol, 200 microg qid, in addition to ipratropium, 40 microg qid for 3 weeks, or vice versa. MEASUREMENTS AND RESULTS: Efficacy end points included morning premedication peak expiratory flow (PEF) during the last week of treatment (primary end point), the area under the curve (AUC) for FEV(1) measured for 6 h after morning dose on the last day of treatment, and symptom scores (from daily diary recordings). Morning PEF and the AUC for FEV(1) were significantly better for formoterol/ipratropium than for salbutamol/ipratropium (p = 0.0003 and p < 0.0001, respectively). The formoterol/ipratropium combination also induced a greater improvement in mean total symptom scores (p = 0.0042). The safety profile of the two treatments was comparable. CONCLUSIONS: In COPD patients requiring combination bronchodilator treatment, the addition of formoterol to regular ipratropium treatment is more effective than the addition of salbutamol.