Association of a low density lipoprotein receptor microsatellite variant with obesity

OBJECTIVE To determine whether a microsatellite polymorphism located towards the 3' end of the low density lipoprotein receptor gene (LDLR) is associated with obesity. DESIGN A cross-sectional case-control study. SUBJECTS One hundred and seven obese individuals, defined as a body mass index (BMI) ≤ 26 kg/m2, and 163 lean individuals, defined as a BMI < 26 kg/m2. MEASUREMENTS BMI, blood pressure, serum lipids, alleles of LDLR microsatellite (106 bp, 108 bp and 112 bp). RESULTS There was a significant association between variants of the LDLR microsatellite and obesity, in the overall tested population, due to a contributing effect in females (χ2 = 12.3, P = 0.002), but not in males (χ2 = 0.3, P = 0.87). In females, individuals with the 106 bp allele were more likely to be lean, while individuals with the 112 bp and/or 108 bp alleles tended to be obese. CONCLUSIONS These results suggest that in females, LDLR may play a role in the development of obesity.

Association of a RFLP for the insulin receptor gene, but not insulin, with essential hypertension

Insulin has cardiovascular actions and patients with essential hypertension display insulin resistance. A cross-sectional study of the R1 RFLP of the insulin receptor gene (INSR) was carried out in 67 hypertensive (HT) and 75 normotensive (NT) subjects whose parents had a similar blood pressure status at age ≥50. The frequency of the minor (+) allele was 0.31 in HTs and 0.44 in NTs, and the difference between observed alleles in all subjects in each group was significant (χ2 = 4.8, P<0.05). Allele frequencies of a BglI RFLP of the insulin gene, however, did not differ between the HT and NT groups. The data thus provide evidence in favour of an association of HT with a polymorphism at the INSR locus (19p 13.3-13.2), so implicating this locus, and possibly a genetic variant of the insulin receptor itself, in HT.

Non-linkage of insulin receptor locus with essential hypertension in an affected pedigree

A recent cross-sectional study has demonstrated a significant association of the R1 RsaI restriction fragment length polymorphism of the insulin receptor gene (INSR) with human essential hypertension. In the present study, an alternative approach, involving linkage analysis, was carried out using 8 hypertensive families with 5 or more affected members. Five of the families were found to be informative and in one of these pedigrees a conclusion of non-linkage of INSR and hypertension could be made on the basis of an obligate recombinant in one generation which yielded a Lod score of - ∞ at a recombination fraction (θ) of zero. In another family, the largest studied, a positive Lod score was obtained at θ = 0, but this was below the level required for a conclusion of linkage. Lod score at θ = 0 for a marker at the insulin locus in this family was negative. The present study has thus demonstrated one pedigree in which hypertension is not linked to the insulin receptor locus.

Association of HincII RFLP of low density lipoprotein receptor gene with obesity in essential hypertensives

Obese (BMI ≥ 26 kg/m 2; n = 51) and lean (BMI <26 kg/m 2; n = 61) Caucasian patients with severe, familial essential hypertension, were compared with respect to genotype and allele frequencies of a HincII RFLP of the low density lipoprotein receptor gene (LDLR). A similar analysis was performed in obese (n = 28) and lean (n = 68) normotensives. A significant association of the C allele of the T→C variant responsible for this RFLP was seen with obesity (χ 2 = 4.6, P = 0.029) in the hypertensive, but not in the normotensive, group (odds ratio = 3.0 for the CC genotype and 2.7 for CT). Furthermore, BMI tracked with genotypes of this allele in the hypertensives (P = 0.046). No significant genotypic relationship was apparent for plasma lipids. Significant linkage disequilibrium was, moreover, noted between the HincII RFLP and an ApaLI RFLP (χ 2 = 33, P<0.0005) that has previously shown even stronger association with obesity (odds ratio 19.6 for cases homozygous for the susceptibility allele and 15.2 for het-erozygotes). The present study therefore adds to our previous evidence implicating LDLR as a locus for obesity in patients with essential hypertension.

An androgen receptor mutation in the MDA-MB-453 cell line model of molecular apocrine breast cancer compromises receptor activity

Recent evidence indicates that the estrogen receptor-a-negative, androgen receptor (AR)- positive molecular apocrine subtype of breast cancer is driven by AR signaling. The MDA-MB-453 cell line is the prototypical model of this breast cancer subtype; its proliferation is stimulated by androgens such as 5a-dihydrotestosterone (DHT) but inhibited by the progestin medroxyprogesterone acetate (MPA) via AR-mediated mechanisms. We report here that the AR gene in MDAMB- 453 cells contains a G-T transversion in exon 7, resulting in a receptor variant with a glutamine to histidine substitution at amino acid 865 (Q865H) in the ligand binding domain. Compared with wild-type AR, the Q865H variant exhibited reduced sensitivity to DHT and MPA in transactivation assays in MDA-MB-453 and PC-3 cells but did not respond to non-androgenic ligands or receptor antagonists. Ligand binding, molecular modeling, mammalian two-hybrid and immunoblot assays revealed effects of the Q865H mutation on ligand dissociation, AR intramolecular interactions, and receptor stability. Microarray expression profiling demonstrated that DHT and MPA regulate distinct transcriptional programs in MDA-MB-453 cells. Gene Set Enrichment Analysis revealed that DHT- but not MPA-regulated genes were associated with estrogen-responsive transcriptomes from MCF-7 cells and the Wnt signaling pathway. These findings suggest that the divergent proliferative responses of MDA-MB-453 cells to DHT and MPA result from the different genetic programs elicited by these two ligands through the AR-Q865H variant. This work highlights the necessity to characterize additional models of molecular apocrine breast cancer to determine the precise role of AR signaling in this breast cancer subtype. Endocrine-Related Cancer (2012) 19 599–613

Using technology to change adult sedentary behaviour, physical activity levels and total wellness

This thesis studied technology’s role in promoting and supporting active lifestyles through behavioural strategies to reduce sedentary time and increase physical activity. The five studies included (1) development of a self-report instrument quantifying daily sedentary behaviour and light-intensity physical activity; (2) establishment of instrument validity and reliability; (3) use of an online personal activity monitor to successfully reduce sedentary time and increase physical activity; (4) identification of positive differences in total wellness as related to high/low levels of sitting time combined with insufficient/sufficient physical activity; and (5) improvement of total wellness through positive changes in sedentary behaviour and physical activity.

Traits of fear resistance and susceptibility in an advanced intercross line

Genetic variability in the strength and precision of fear memory is hypothesised to contribute to the etiology of anxiety disorders, including post-traumatic stress disorder. We generated fear-susceptible (F-S) or fear-resistant (F-R) phenotypes from an F8 advanced intercross line (AIL) of C57BL/6J and DBA/2J inbred mice by selective breeding. We identified specific traits underlying individual variability in Pavlovian conditioned fear learning and memory. Offspring of selected lines differed in the acquisition of conditioned fear. Furthermore, F-S mice showed greater cued fear memory and generalised fear in response to a novel context than F-R mice. F-S mice showed greater basal corticosterone levels and hypothalamic corticotrophin-releasing hormone (CRH) mRNA levels than F-R mice, consistent with higher hypothalamic-pituitary-adrenal (HPA) axis drive. Hypothalamic mineralocorticoid receptor and CRH receptor 1 mRNA levels were decreased in F-S mice as compared with F-R mice. Manganese-enhanced magnetic resonance imaging (MEMRI) was used to investigate basal levels of brain activity. MEMRI identified a pattern of increased brain activity in F-S mice that was driven primarily by the hippocampus and amygdala, indicating excessive limbic circuit activity in F-S mice as compared with F-R mice. Thus, selection pressure applied to the AIL population leads to the accumulation of heritable trait-relevant characteristics within each line, whereas non-behaviorally relevant traits remain distributed. Selected lines therefore minimise false-positive associations between behavioral phenotypes and physiology. We demonstrate that intrinsic differences in HPA axis function and limbic excitability contribute to phenotypic differences in the acquisition and consolidation of associative fear memory. Identification of system-wide traits predisposing to variability in fear memory may help in the direction of more targeted and efficacious treatments for fear-related pathology. Through short-term selection in a B6D2 advanced intercross line we created mouse populations divergent for the retention of Pavlovian fear memory. Trait distinctions in HPA-axis drive and fear network circuitry could be made between naïve animals in the two lines. These data demonstrate underlying physiological and neurological differences between Fear-Susceptible and Fear-Resistant animals in a natural population. F-S and F-R mice may therefore be relevant to a spectrum of disorders including depression, anxiety disorders and PTSD for which altered fear processing occurs.

IL-20 is epigenetically regulated in NSCLC and down regulates the expression of VEGF

Background IL-20 is a pleiotrophic member of the IL-10 family and plays a role in skin biology and the development of haematopoietic cells. Recently, IL-20 has been demonstrated to have potential anti-angiogenic effects in non-small cell lung cancer (NSCLC) by down regulating COX-2. Methods The expression of IL-20 and its cognate receptors (IL-20RA/B and IL-22R1) was examined in a series of resected fresh frozen NSCLC tumours. Additionally, the expression and epigenetic regulation of this family was examined in normal bronchial epithelial and NSCLC cell lines. Furthermore, the effect of IL-20 on VEGF family members was examined. Results The expression of IL-20 and its receptors are frequently dysregulated in NSCLC. IL-20RB mRNA was significantly elevated in NSCLC tumours (p < 0.01). Protein levels of the receptors, IL-20RB and IL-22R1, were significantly increased (p < 0.01) in the tumours of NSCLC patients. IL-20 and its receptors were found to be epigenetically regulated through histone post-translational modifications and DNA CpG residue methylation. In addition, treatment with recombinant IL-20 resulted in decreased expression of the VEGF family members at the mRNA level. Conclusions This family of genes are dysregulated in NSCLC and are subject to epigenetic regulation. Whilst the anti-angiogenic properties of IL-20 require further clarification, targeting this family via epigenetic means may be a viable therapeutic option in lung cancer treatment. © 2011 Elsevier Ltd. All rights reserved.

COX-derived prostanoid pathways in gastrointestinal cancer development and progression : novel targets for prevention and intervention

Arachidonic acid metabolism through cyclooxygenase (COX) pathways leads to the generation of biologically active eicosanoids. Eicosanoid expression levels vary during development and progression of gastrointestinal (GI) malignancies. COX-2 is the major COX-isoform responsible for G.I. cancer development/progression. COX-2 expression increases during progression from a normal to cancerous state. Evidence from observational studies has demonstrated that chronic NSAID use reduces the risk of cancer development, while both incidence and risk of death due to G.I. cancers were significantly reduced by daily aspirin intake. A number of randomized controlled trials (APC trial, Prevention of Sporadic Adenomatous Polyps trial, APPROVe trial) have also shown a significant protective effect in patients receiving selective COX-2 inhibitors. However, chronic use of selective COX-2 inhibitors at high doses was associated with increased cardiovascular risk, while NSAIDs have also been associated with increased risk. More recently, downstream effectors of COX-signaling have been investigated in cancer development/progression. PGE 2, which binds to both EP and PPAR receptors, is the major prostanoid implicated in the carcinogenesis of G.I. cancers. The role of TXA 2 in G.I. cancers has also been examined, although further studies are required to uncover its role in carcinogenesis. Other prostanoids investigated include PGD 2 and its metabolite 15d-PGJ2, PGF 1α and PGI 2. Targeting these prostanoids in G.I. cancers has the promise of avoiding cardiovascular toxicity associated with chronic selective COX-2 inhibition, while maintaining anti-tumor reactivity.A progressive sequence from normal to pre-malignant to a malignant state has been identified in G.I. cancers. In this review, we will discuss the role of the COX-derived prostanoids in G.I. cancer development and progression. Targeting these downstream prostanoids for chemoprevention and/or treatment of G.I. cancers will also be discussed. Finally, we will highlight the latest pre-clinical technologies as well as avenues for future investigation in this highly topical research field. © 2011 Elsevier B.V.

Source apportionment of airborne particulate matter : an overview of Australian and New Zealand studies

Despite the existence of air quality guidelines in Australia and New Zealand, the concentrations of particulate matter have exceeded these guidelines on several occasions. To identify the sources of particulate matter, examine the contributions of the sources to the air quality at specific areas and estimate the most likely locations of the sources, a growing number of source apportionment studies have been conducted. This paper provides an overview of the locations of the studies, salient features of the results obtained and offers some perspectives for the improvement of future receptor modelling of air quality in these countries. The review revealed that because of its advantages over alternative models, Positive Matrix Factorisation (PMF) was the most commonly applied model in the studies. Although there were differences in the sources identified in the studies, some general trends were observed. While biomass burning was a common problem in both countries, the characteristics of this source varied from one location to another. In New Zealand, domestic heating was the highest contributor to particle levels on days when the guidelines were exceeded. On the other hand, forest back-burning was a concern in Brisbane while marine aerosol was a major source in most studies. Secondary sulphate, traffic emissions, industrial emissions and re-suspended soil were also identified as important sources. Some unique species, for example, volatile organic compounds and particle size distribution were incorporated into some of the studies with results that have significant ramifications for the improvement of air quality. Overall, the application of source apportionment models provided useful information that can assist the design of epidemiological studies and refine air pollution reduction strategies in Australia and New Zealand.

Receptor tyrosine kinases and their activation in melanoma

Receptor tyrosine kinases (RTKs) and their downstream signalling pathways have long been hypothesized to play key roles in melanoma development. A decade ago, evidence was derived largely from animal models, RTK expression studies and detection of activated RAS isoforms in a small fraction of melanomas. Predictions that overexpression of specific RTKs implied increased kinase activity and that some RTKs would show activating mutations in melanoma were largely untested. However, technological advances including rapid gene sequencing, siRNA methods and phospho-RTK arrays now give a more complete picture. Mutated forms of RTK genes including KIT, ERBB4, the EPH and FGFR families and others are known in melanoma. Additional over- or underexpressed RTKs and also protein tyrosine phosphatases (PTPs) have been reported, and activities measured. Complex interactions between RTKs and PTPs are implicated in the abnormal signalling driving aberrant growth and survival in malignant melanocytes, and indeed in normal melanocytic signalling including the response to ultraviolet radiation. Kinases are considered druggable targets, so characterization of global RTK activity in melanoma should assist the rational development of tyrosine kinase inhibitors for clinical use. © 2011 John Wiley & Sons A/S.

Regulation of EP receptors in non-small cell lung cancer by epigenetic modifications

Background: Cyclooxygenase (COX)-2 is frequently overexpressed in non-small cell lung cancer (NSCLC) and results in increased levels of prostaglandin E2 (PGE 2), an important signalling molecule implicated in tumourigenesis. PGE 2 exerts its effects through the E prostanoid (EP) receptors (EPs1-4). Methods: The expression and epigenetic regulation of the EPs were evaluated in a series of resected fresh frozen NSCLC tumours and cell lines. Results: EP expression was dysregulated in NSCLC being up and downregulated compared to matched control samples. For EPs1, 3 and 4 no discernible pattern emerged. EP2 mRNA however was frequently downregulated, with low levels being observed in 13/20 samples as compared to upregulation in 5/20 samples examined. In NSCLC cell lines DNA CpG methylation was found to be important for the regulation of EP3 expression, the demethylating agent decitabine upregulating expression. Histone acetylation was also found to be a critical regulator of EP expression, with the histone deacteylase inhibitors trichostatin A, phenylbutyrate and suberoylanilide hydroxamic acid inducing increased expression of EPs2-4. Direct chromatin remodelling was demonstrated at the promoters for EPs2-4. Conclusions: These results indicate that EP expression is variably altered from tumour to tumour in NSCLC. EP2 expression appears to be predominantly downregulated and may have an important role in the pathogenesis of the disease. Epigenetic regulation of the EPs may be central to the precise role COX-2 may play in the evolution of individual tumours. © 2009 Elsevier Ltd. All rights reserved.

Randomized phase II trial of the efficacy and safety of trastuzumab combined with docetaxel in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer administered as first-line treatment : the M77001 study group

Purpose: This randomized, multicenter trial compared first-line trastuzumab plus docetaxel versus docetaxel alone in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC). Patients and Methods: Patients were randomly assigned to six cycles of docetaxel 100 mg/m 2 every 3 weeks, with or without trastuzumab 4 mg/kg loading dose followed by 2 mg/kg weekly until disease progression. Results: A total of 186 patients received at least one dose of the study drug. Trastuzumab plus docetaxel was significantly superior to docetaxel alone in terms of overall response rate (61% v 34%; P = .0002), overall survival (median, 31.2 v 22.7 months; P = .0325), time to disease progression (median, 11.7 v 6.1 months; P = .0001), time to treatment failure (median, 9.8 v 5.3 months; P = .0001), and duration of response (median, 11.7 v 5.7 months; P = .009). There was little difference in the number and severity of adverse events between the arms. Grade 3 to 4 neutropenia was seen more commonly with the combination (32%) than with docetaxel alone (22%), and there was a slightly higher incidence of febrile neutropenia in the combination arm (23% v 17%). One patient in the combination arm experienced symptomatic heart failure (1%). Another patient experienced symptomatic heart failure 5 months after discontinuation of trastuzumab because of disease progression, while being treated with an investigational anthracycline for 4 months. Conclusion: Trastuzumab combined with docetaxel is superior to docetaxel alone as first-line treatment of patients with HER2-positive MBC in terms of overall survival, response rate, response duration, time to progression, and time to treatment failure, with little additional toxicity. © 2005 by American Society of Clinical Oncology.

Somatostatin receptor expression in lung cancer

Experimental evidence suggests that somatostatin analogues may have a role to play in the management of lung tumours. We evaluated membrane preparations of nine small cell lung cancer (SCLC) cell lines and of tumour samples from 3 patients with non-small cell lung cancer (NSCLC), 1 patient with an atypical carcinoid and another with a bronchial carcinoid for the presence of specific binding sites for RC-160, a potent growth inhibitory octapeptide analogue of somatostatin. Specific binding was noted on six of nine SCLC lines. Radio-receptor assay on the cell line NCI H 69 showed evidence of two specific binding sites for RC-160, one with high affinity and the other with low affinity. Binding sites were also found on all five tumour samples. Scatchard analysis indicated the presence of a single class of receptors with high affinity in each case. Histological assessment of the resected specimens before binding assay showed them to be comprised of tumour cells and necrotic tissue, stroma and/or inflammatory cells. Therefore, the specific binding of RC-160 may be to tissues other than the tumour cells. In 3 patients, from whom the tumour samples were obtained, radiolabelled somatostatin analogue scintigraphy using [111In] pentetreotide was performed prior to surgery. In all cases, the radiolabel localised the disease. This study demonstrates the presence of specific binding sites for RC-160 in SCLC. Furthermore, the detection of specific binding in vitro and in vivo in NSCLC and intrapulmonary carcinoids demonstrates that these tumours contain cells which express specific binding sites for somatostatin. These results suggest that RC-160 may have a role toplay as a therapeutic agent in lung cancer.

Somatostatin, its receptors and analogs, in lung cancer

Despite developments in diagnosis and treatment, lung cancer is the commonest cause of cancer death in Europe and North America. Due to increasing cigarette consumption, the incidence of the disease and resultant mortality is rising dramatically in women. Novel approaches to the management of lung cancer are urgently required. Somatostatin is a tetradecapeptide first identified in the pituitary and subsequently throughout the body particularly in neuroendocrine cells of the pancreas and gastrointestinal tract and the nervous system. The peptide has numerous functions including inhibition of hormone release, immunomodulation and neurotransmission and is an endogenous inhibitor of cell proliferation and angiogenesis. Somatostatin and its analogs, including octreotide (SMS 201-995), somatuline (BIM 23014) and vapreotide (RC-160), act by binding to specific somatostatin receptors (SSTR) of which there are 5 principal subtypes, SSTR-1-5. Although elevated plasma somatostatin levels may be detected in 14-15% of patients, tumor cell expression appears rare. SSTR may be expressed by lung tumors, particularly small cell lung cancer and bronchial carcinoid disease. [111In]pentetreotide scintigraphy may have a role to play in the localization and staging of lung cancers both before and following treatment, and in detecting relapsed disease. The potential role of radiolabelled somatostatin analogs as radiotherapeutic agents in the management of lung cancer is currently being explored. Somatostatin analog therapy results in significant growth inhibition of both SSTR-positive and SSTR-negative lung tumors in vivo. Recent work indicates that these agents may enhance the efficacy of chemotherapeutic agents in the treatment of solid tumors including lung cancer. Copyright © 2001 S. Karger AG, Basel.