Purpose: The steroid hormone 1,25-dihydroxyvitamin D 3 is thought to protect against breast cancer. The actions of 1,25-dihydroxyvitamin D 3 are mediated via the vitamin D receptor (VDR), and a number of polymorphisms in the VDR gene have been identified. These result in distinct genotypes, some of which may alter susceptibility to breast cancer. We have investigated whether specific VDR gene polymorphisms are associated with breast cancer risk in a United Kingdom Caucasian population.Experimental Design: In a retrospective case-control study, female breast cancer patients (n ‫؍‬ 398) and control women (n ‫؍‬ 427) were recruited, and three VDR polymorphisms were determined.Results: The 3 VDR polymorphisms BsmI and variable-length poly(adenylate) sequence were both significantly associated with breast cancer risk; odds ratios (adjusted for age menopausal status and hormone replacement therapy usage) for bb genotype versus BB genotype ‫؍‬ 1.92 (95% confidence interval, 1.20 -3.10; P < 0.01) and for LL versus SS ‫؍‬ 1.94 (95% confidence interval, 1.20 -3.14; P < 0.01). A 5 VDR gene variant, FokI, was not associated with breast cancer risk when analyzed in isolation (P > 0.05). However, FokI did modulate the increased risk associated with the bb/LL genotype such that possession of one or more F alleles together with the bb/LL genotype augmented breast cancer risk. Furthermore, the highest proportion of bb and FFLL/ FfLL genotypes occurred in women with metastatic breast cancer.Conclusions: VDR polymorphisms are associated with breast cancer risk and may be associated with disease progression. Additional investigations into how different genotypes may affect the functional mechanisms of the VDR will provide a better strategy for identifying women at risk of breast cancer and for developing improved treatments.

There is increasing evidence that vitamin D can protect against breast cancer. The actions of vitamin D are mediated via the vitamin D receptor (VDR). We have investigated whether polymorphisms in the VDR gene are associated with altered breast cancer risk in a UK Caucasian population. We recruited 241 women following a negative screening mammogram and 181 women with known breast cancer. The VDR polymorphism BsmI, an intronic 3′ gene variant, was significantly associated with increased breast cancer risk: odds ratio bb vs BB genotype = 2.32 (95% CI, 1.23–4.39). The BsmI polymorphism was in linkage disequilibrium with a candidate translational control site, the variable length poly (A) sequence in the 3′ untranslated region. Thus, the ‘L’ poly (A) variant was also associated with a similar breast cancer risk. A 5′ VDR gene variant, FokI, was not associated with breast cancer risk. Further investigations into the mechanisms of interactions of the VDR with other environmental and/or genetic influences to alter breast cancer risk may lead to a new understanding of the role of vitamin D in the control of cellular and developmental pathways. © 2001 Cancer Research Campaign http://www.bjcancer.com

Immunoreactivity to endothelin was detected in conditioned culture medium from both canine and porcine tracheal epithelial cells. Gel permeation chromatography and fast protein liquid chromatography were used to confirm the identity of the endothelin. The two peaks demonstrated on fast protein liquid chromatography co-eluted with endothelin 1 and endothelin 3 respectively.Endothelin; (Airway epithelial cell)

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Summary. The response of the islet amyloid polypeptide gene to chronic dexamethasone treatment in adult rats was investigated. After 12 daily injections, rats were severely underweight and fasting blood glucose levels were elevated. When pancreatic mRNA was analysed, a 16-fold elevation in islet amyloid polypeptide mRNA was observed with only a fourfold increase in insulin mRNA levels. Pancreatic islet amyloid polypeptide and insulin mRNA levels were also determined 12 days after streptozotocin treatment. In these rats, which were not severely diabetic, the reduction in islet amyloid polypeptide mRNA levels was sixfold less than the reduction in insulin mRNA levels. In both these models of diabetes the ratio of islet amyloid polypeptide to insulin mRNA levels was raised. This would not be expected if the physiological role of islet amyloid polypeptide is as a simple hyperglycaemic agent opposing insulin action or release.Key words: Islet amyloid polypeptide, amylin, Type 2 (noninsulin-dependent) diabetes mellitus, mRNA, streptozotocin, dexamethasone, rat.A 37 amino acid peptide with homology to calcitonin gene related peptide (CGRP) has recently been characterised from the pancreatic amyloid deposits of a Type 2 (non-insulin-dependent) diabetic patient [1] and from an insulinoma [2]. This peptide is now known as islet amyloid polypeptide (IAPP) [2], or amylin [3]. IAPP opposes the action of insulin on isolated muscle preparations [3] and inhibits insulin release from rat islets in vitro [4]. Using a cloned DNA probe representing the rat IAPP coding sequence, we have recently found IAPP to be present in the stomach as well as the pancreas [5]. A variety of evidence thus suggests that this peptide may play an important role in the control of carbohydrate metabolism. We therefore decided to study the expression of the IAPP gene in the rat pancreas after treatment with agents known to affect carbohydrate metabolism. In particular, we wanted to know whether IAPP and insulin levels could be regulated independently and whether induced peripheral insulin resistance would lead to changes in the pancreas which might have relevance to amyloid deposition in man. Materials and methods Drug treatmentsAdult male Wistar rats of 125-150g were divided into 3 groups: (1) controls (n = 5) fed ad libitum on standard rat chow, (2) dexamethasone (n = 5) 2 mg/kg injected i.p. each day for 12 days, and (3) streptozotocin treatment (n =24) 60 mg/kg injected i.v. 12 days prior to analysis. After treatment, rats were starved overnight and killed by cervical dislocation after ether anaesthesia. Blood was taken for glucose measurements and the pancreas was dissected and frozen under liquid nitrogen for RNA extraction. RNA analysisTotal RNA was prepared from the frozen tissues and analysed by Northern blotting with rat IAPP and insulin probes as previously [5]. However, to minimise handling, polyadenylated RNA was not purified in the present experiments and 30 ~g of total RNA was loaded onto each track of these gels. Stringent washing conditi...

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The islet amyloid polypeptide (IAPP) gene is expressed primarily in the islet beta-cell and the peptide is co-secreted with insulin. To investigate mechanisms important in its regulation, we have used the electrophoretic mobility-shift assay and methylation interference to determine systematically sites of DNA-protein interactions in the human IAPP promoter. We identified beta-cell-specific DNA-protein complexes at three sites, each of which contained a consensus binding site for insulin upstream factor I (IUF-I). This complex was displaced with an antiserum to IUF-1, confirming that IUF-1 binds to the human IAPP promoter in vitro. We have also identified a DNA-protein complex within the region -220/-250 in both beta- and non-beta-cell lines. This region contains a motif with partial identity with the binding site for the ubiquitous transcription factor upstream stimulatory factor (USF), which binds to the human insulin promoter. However, purified USF was not able to bind to this putative site in the IAPP promoter and an oligonucleotide containing a functional USF-binding site was unable to displace binding from the IAPP oligonucleotide. Methylation interference revealed that the DNA-protein complex binds to a sequence that overlaps the USE-like sequence, and may therefore be a novel helix-loop-helix protein. These results suggest that, although both IAPP and insulin are beta-cell peptides, IAPP contains regulatory regions both common to and distinct from insulin.

The presence of islet amyloid polypeptide in amyloid within pancreatic islet cells in Type 2 (non-insulin-dependent) diabetes, and its reported inhibition of glucose uptake by skeletal muscle in vitro, has prompted speculation concerning its role in the pathogenesis of diabetes. We investigated the effect of infused synthetic amidated human islet amyloid polypeptide (mol. wt. 3904, confirmed by mass spectroscopy) on intravenous glucose tolerance. Seven healthy, non-obese volunteers (age +/- SD, 27 +/- 4 years) were infused over 50 min with normal (0.9%) saline or islet amyloid polypeptide at 50 pmol.kg-1.min-1. After 20 min, a bolus of 0.5 g/kg glucose was given within 1 min and blood sampling continued for up to 60 min. Circulating concentrations of islet amyloid polypeptide reached at steady state were 1130 +/- 90 pmol/l. The calculated half-life was 11.8 +/- 0.9 min, metabolic clearance rate 5.7 +/- 0.6 ml.kg-1.min-1 and apparent distribution space therefore 94 +/- 12 ml/kg. However, islet amyloid polypeptide was found to have no effect on the peak value reached, or the total area under the curve for plasma glucose, insulin or glucagon following intravenous glucose. This study suggests circulating islet amyloid polypeptide may not be an important influence on intravenous glucose tolerance in man.