Dominant-negative features of mutant TP53 in germline carriers have limited impact on cancer outcomes

Germline TP53 mutations result in cancer proneness syndromes known as Li-Fraumeni, Li-Fraumeni-like, and nonsyndromic predisposition with or without family history. To explore genotype/phenotype associations, we previously adopted a functional classification of all germline TP53 mutant alleles based on transactivation. Severe deficiency (SD) alleles were associated with more severe cancer proneness syndromes, and a larger number of tumors, compared with partial deficiency (PD) alleles. Because mutant p53 can exert dominant-negative (DN) effects, we addressed the relationship between DN and clinical manifestations. We reasoned that DN effects might be stronger in familial cancer cases associated with germline TP53 mutations, where mutant alleles coexist with the wild-type allele since conception. We examined 104 p53 mutant alleles with single amino acid substitutions described in the IARC germline database for (i) transactivation capability and (ii) capacity to reduce the activity of the wild-type allele (i.e., DN effect) using a quantitative yeast-based assay. The functional classifications of p53 alleles were then related to clinical variables. We confirmed that a classification based on transactivation alone can identify familial cancer cases with more severe clinical features. Classification based on DN effects allowed us to highlight similar associations but did not reveal distinct clinical subclasses of SD alleles, except for a correlation with tumor tissue prevalence. We conclude that in carriers of germline TP53 mutations transactivation-based classification of TP53 alleles appears more important for genotype/phenotype correlations than DN effects and that haplo-insufficiency of the TP53 gene is an important factor in cancer proneness in humans.     

Regulation of integrins by conformation and traffic: it takes two to tango

In multicellular organisms, the execution of complex morphogenetic events, such as gastrulation or vascular morphogenesis, depends on the dynamic modulation of adhesion. Guidance cues, such as chemokines, growth factors, and semaphorins control the attachment of cells to extracellular matrix proteins by regulating the conformational activation of integrin receptors. The endo-exocytic traffic of integrins back and forth from the plasma membrane represents another crucial regulatory aspect in cell adhesion and motility. Recent work added an additional layer of complexity by indicating that distinct molecular machineries are required for trafficking active and inactive integrins.     

Mechanistic studies on two dinuclear organogold(III) compounds showing appreciable antiproliferative properties and a high redox stability

Two dinuclear oxo-bridged organogold(III) compounds, namely [(N,N,C)(2)Au(2)(μ-O)][PF(6)](2) (with N,N,CH = 6-(1-methylbenzyl)-2,2'-bipyridine, Au(2)O1; or 6-(1,1-dimethylbenzyl)-2,2'-bipyridine, Au(2)O2), were previously prepared and characterised. Their solution chemistry under physiological-like conditions has been investigated here as well as their in vitro antiproliferative properties. Notably, these compounds reveal a marked redox stability even in the presence of effective biological reductants such as ascorbic acid and glutathione. The two dinuclear gold(iii) compounds were evaluated for cytotoxic actions against a representative panel of 12 human tumor cell lines, in comparison to respective mononuclear parent compounds [(N,N,C)AuOH][PF(6)], and appreciable biological activity could be highlighted. The reactions of Au(2)O1 and Au(2)O2 with a few model proteins were studied and the ability to form metallodrug-protein adducts monitored through ESI MS methods. Typical adducts were identified where the protein is associated to monometallic gold fragments; in these adducts gold remains in the oxidation state +3 and conserves its organic ligand. A direct comparison of the biological profiles of these binuclear organogold(III) compounds with those previously reported for a series of dinuclear oxo-bridged complexes [(N,N)(2)Au(2)(μ-O)(2)][PF(6)](2) (N,N = 6(6')-substituted 2,2'-bipyridines) named Auoxo's was carried out. It emerges that the greater cytotoxicity of the latter is mainly due to the greater oxidising power of their gold(III) centres and to propensity to generate gold(i) species; in contrast, the here described bimetallic organogold(III) complexes manifest a far higher redox stability in the biological milieu coupled to lower, but still significant, antiproliferative properties. Different molecular mechanisms are thus hypothesised for these two classes of dinuclear gold(III) agents.     

Polymeric membranes for guided bone regeneration

In this review, different barrier membranes for guided bone regeneration (GBR) are described as a useful surgical technique to enhance bone regeneration in damaged alveolar sites before performing implants and fitting other dental appliances. The GBR procedure encourages bone regeneration through cellular exclusion and avoids the invasion of epithelial and connective tissues that grow at the defective site instead of bone tissue. The barrier membrane should satisfy various properties, such as biocompatibility, non-immunogenicity, non-toxicity, and a degradation rate that is long enough to permit mechanical support during bone formation. Other characteristics such as tissue integration, nutrient transfer, space maintenance and manageability are also of interest. In this review, various non-resorbable and resorbable commercially available membranes are described, based on expanded polytetrafluoroethylene, poly(lactic acid), poly(glycolic acid) and their copolymers. The polyester-based membranes are biodegradable, permit a single-stage procedure, and have higher manageability than non-resorbable membranes; however, they have shown poor biocompatibility. In contrast, membranes based on natural materials, such as collagen, are biocompatible but are characterized by poor mechanical properties and stability due to their early degradation. Moreover, new approaches are described, such as the use of multi-layered, graft-copolymer-based and composite membranes containing osteoconductive ceramic fillers as alternatives to conventional membranes.     

Clinical features predicting identification of CDKN2A mutations in Italian patients with familial cutaneous melanoma

CDKN2A is the most common, most penetrant gene whom germline mutations predisposing to cutaneous familial melanoma (FAM). Multiple primary melanoma (MPM), early age at onset, >2 affected members and pancreatic cancer are consistent features predicting positive test. However, the impact that cumulative clinical features have on the likelihood of molecular testing is unknown. In this work, genotype-phenotype correlations focused on selected clinical features were performed in 100 Italian FAM unrelated patients. Molecular studies of CDKN2A mutations were performed by direct sequencing. Statistical study included multiple correspondence analysis, uni- and multivariate analyses, and individual patient's probability calculation. MPM, >2 affected family members, Breslow thickness >0.4mm, and age at onset ≤41 years were the unique independent features predicting positive CDKN2A screening. The rate of positive testing ranged from 93.2% in the presence of all of them, to 0.4% in their absence. The contribution of each of them was quantified accordingly, with MPM being the most significant. These findings confirm previous data and add novel insights for the role of accurate patients' selection in CDKN2A screening.     

Premature decline of serum total testosterone in HIV-infected men in the HAART-era

Background

Testosterone (T) deficiency remains a poorly understood issue in men with Human Immunodeficiency Virus (HIV). We investigated the gonadal status in HIV-infected men in order to characterize T deficiency and to identify predictive factors for low serum T.

Methodology/Principal Findings

We performed a cross-sectional, observational study on 1325 consecutive HIV male outpatients, most of them having lipodystrophy. Serum total T<300 ng/dL was used as the threshold for biochemical T deficiency. Morning serum total T, luteinizing hormone (LH), estradiol, HIV parameters, and body composition parameters by CT-scan and Dual-Energy-X-ray-Absorptiometry were measured in each case. Sexual behavior was evaluated in a subset of 247 patients. T deficiency was found in 212 subjects, especially in the age range 40–59, but was frequent even in younger patients. T deficiency occurred mainly in association with low/normal serum LH. Adiposity was higher in subjects with T deficiency (p<0.0001) and both visceral adipose tissue and body mass index were the main negative predictors of serum total T. Osteoporosis and erectile dysfunction were present in a similar percentage in men with or without T deficiency.

Conclusions/Significance

Premature decline of serum T is common (16%) among young/middle-aged HIV-infected men and is associated with inappropriately low/normal LH and increased visceral fat. T deficiency occurs at a young age and may be considered an element of the process of premature or accelerated aging known to be associated with HIV infection. The role of HIV and/or HIV infection treatments, as well as the role of the general health state on the gonadal axis, remains, in fact, to be elucidated. Due to the low specificity of signs and symptoms of hypogonadism in the context of HIV, caution is needed in the diagnosis of hypogonadism in HIV-infected men with biochemical low serum T levels.     

Genes involved in vasoconstriction and vasodilation system affect salt-sensitive hypertension

The importance of excess salt intake in the pathogenesis of hypertension is widely recognized. Blood pressure is controlled primarily by salt and water balance because of the infinite gain property of the kidney to rapidly eliminate excess fluid and salt. Up to fifty percent of patients with essential hypertension are salt-sensitive, as manifested by a rise in blood pressure with salt loading. We conducted a two-stage genetic analysis in hypertensive patients very accurately phenotyped for their salt-sensitivity. All newly discovered never treated before, essential hypertensives underwent an acute salt load to monitor the simultaneous changes in blood pressure and renal sodium excretion. The first stage consisted in an association analysis of genotyping data derived from genome-wide array on 329 subjects. Principal Component Analysis demonstrated that this population was homogenous. Among the strongest results, we detected a cluster of SNPs located in the first introns of PRKG1 gene (rs7897633, p = 2.34E-05) associated with variation in diastolic blood pressure after acute salt load. We further focused on two genetic loci, SLC24A3 and SLC8A1 (plasma membrane sodium/calcium exchange proteins, NCKX3 and NCX1, respectively) with a functional relationship with the previous gene and associated to variations in systolic blood pressure (the imputed rs3790261, p = 4.55E-06; and rs434082, p = 4.7E-03). In stage 2, we characterized 159 more patients for the SNPs in PRKG1, SLC24A3 and SLC8A1. Combined analysis showed an epistatic interaction of SNPs in SLC24A3 and SLC8A1 on the pressure-natriuresis (p interaction = 1.55E-04, p model = 3.35E-05), supporting their pathophysiological link in cellular calcium homeostasis. In conclusions, these findings point to a clear association between body sodium-blood pressure relations and molecules modulating the contractile state of vascular cells through an increase in cytoplasmic calcium concentration.