Progressive telomere dysfunction causes cytokinesis failure and leads to the accumulation of polyploid cells

Most cancer cells accumulate genomic abnormalities at a remarkably rapid rate, as they are unable to maintain their chromosome structure and number. Excessively short telomeres, a known source of chromosome instability, are observed in early human-cancer lesions. Besides telomere dysfunction, it has been suggested that a transient phase of polyploidization, in most cases tetraploidization, has a causative role in cancer. Proliferation of tetraploids can gradually generate subtetraploid lineages of unstable cells that might fire the carcinogenic process by promoting further aneuploidy and genomic instability. Given the significance of telomere dysfunction and tetraploidy in the early stages of carcinogenesis, we investigated whether there is a connection between these two important promoters of chromosomal instability. We report that human mammary epithelial cells exhibiting progressive telomere dysfunction, in a pRb deficient and wild-type p53 background, fail to complete the cytoplasmatic cell division due to the persistence of chromatin bridges in the midzone. Flow cytometry together with fluorescence in situ hybridization demonstrated an accumulation of binucleated polyploid cells upon serial passaging cells. Restoration of telomere function through hTERT transduction, which lessens the formation of anaphase bridges by recapping the chromosome ends, rescued the polyploid phenotype. Live-cell imaging revealed that these polyploid cells emerged after abortive cytokinesis due to the persistence of anaphase bridges with large intervening chromatin in the cleavage plane. In agreement with a primary role of anaphase bridge intermediates in the polyploidization process, treatment of HMEC-hTERT cells with bleomycin, which produces chromatin bridges through illegimitate repair, resulted in tetraploid binucleated cells. Taken together, we demonstrate that human epithelial cells exhibiting physiological telomere dysfunction engender tetraploid cells through interference of anaphase bridges with the completion of cytokinesis. These observations shed light on the mechanisms operating during the initial stages of human carcinogenesis, as they provide a link between progressive telomere dysfunction and tetraploidy.     

Synthesis of novel 3-(alkylcarbamoyl)-2-aryl-1,2-dihydro-6,7-(methylenedioxy)-3H-quinazolin-4-ones as anticonvulsant agents

A series of 3-(alkylcarbamoyl)-2-aryl-1,2-dihydro-6,7-(methylenedioxy)-3H-quinazolin-4-ones, compounds 3-6, were synthesized, and screened as anticonvulsant agents in DBA/2 mice against sound-induced seizure (Table). The new compounds were found to display anticonvulsant properties inferior to those of the known dehydro congeners 1 and 2. The binding affinities of 1-6 at the AMPA and NMDA receptors were also evaluated.     

Synthesis and biological activity of nociceptin/orphanin FQ analogues substituted in position 7 or 11 with Calpha,alpha-dialkylated amino acids

Previous structure-activity and NMR studies on nociceptin/orphanin FQ (N/OFQ) demonstrated that Aib substitution of Ala(7) and/or Ala(11) increases the peptide potency through an alpha helix structure induction mechanism. On these bases we synthesised and evaluated pharmacologically in the mouse vas deferens assay a series of N/OFQ-NH(2) analogues substituted in position 7 and 11 with Calpha,alpha-disubstituted cyclic, linear and branched amino acids. None of the 20 novel N/OFQ analogues produced better results than [Aib(7)]N/OFQ-NH(2). Thus, this substitution was combined with other chemical modifications known to modulate peptide potency and/or efficacy generating compound 21 [Nphe(1)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (coded as UFP-111), compound 22 [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112) and compound 23 [Phe(1)Psi(CH(2)-NH)Gly(2)(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-113). These novel peptides behaved as highly potent NOP receptor ligands showing full (UFP-112) and partial (UFP-113) agonist and pure antagonist (UFP-111) activities in a series of in vitro functional assays performed on pharmacological preparations expressing native as well as recombinant NOP receptors.     

Protective effect of orally administered carnosine on bleomycin-induced lung injury

Carnosine is an endogenously synthesized dipeptide composed of beta-alanine and L-histidine. It acts as a free radical scavenger and possesses antioxidant properties. Carnosine reduces proinflammatory and profibrotic cytokines such as transforming growth factor-beta (TGF-beta), IL-1, and TNF-alpha in different experimental settings. In the present study, we investigated the efficacy of carnosine on the animal model of bleomycin-induced lung injury. Mice were subjected to intratracheal administration of bleomycin and were assigned to receive carnosine daily by an oral bolus of 150 mg/kg. One week after fibrosis induction, bronchoalveolar lavage (BAL) cell counts and TGF-beta levels, lung histology, and immunohistochemical analyses for myeloperoxidase, TGF-beta, inducible nitric oxide synthase, nitrotyrosine, and poly(ADP-ribose) polymerase were performed. Finally, apoptosis was quantified by terminal deoxynucleotidyltransferase-mediated UTP end-labeling assay. After bleomycin administration, carnosine-treated mice exhibited a reduced degree of lung damage and inflammation compared with wild-type mice, as shown by the reduction of 1) body weight, 2) mortality rate, 3) lung infiltration by neutrophils (myeloperoxidase activity and BAL total and differential cell counts), 4) lung edema, 5) histological evidence of lung injury and collagen deposition, 6) lung myeloperoxidase, TGF-beta, inducible nitric oxide synthase, nitrotyrosine, and poly(ADP-ribose) polymerase immunostaining, 7) BAL TGF-beta levels, and 8) apoptosis. Our results indicate that orally administered carnosine is able to prevent bleomycin-induced lung injury likely through its direct antioxidant properties. Carnosine is already available for human use. It might prove useful as an add-on therapy for the treatment of fibrotic disorders of the lung where oxidative stress plays a role, such as for idiopathic pulmonary fibrosis, a disease that still represents a major challenge to medical treatment.     

Species richness and wood production: a positive association in Mediterranean forests

A major debate in the study of biodiversity concerns its influence on ecosystem functioning. We compared whether wood production in forests was associated with tree functional group identity (i.e. deciduous, conifer or sclerophylous), tree species richness (1–≥ 5) and tree functional group richness (1–3) by comparing more than 5000 permanent plots distributed across Catalonia (NE Spain). Deciduous forests were more productive than coniferous and sclerophylous forests. Wood production increased with tree species richness. However, functional group richness increased wood production only in sclerophylous forests. When other forest structure, environmental variables and management practices were included in the analysis, tree functional group identity and species richness still remained significant, while functional species richness did not. Our survey indicates that across a regional scale, and across a broad range of environmental conditions, a significant positive association exists between local tree species richness and wood production at least in typical early successional Mediterranean-type forests.     

Synthetic heterotrimeric collagen peptides as mimics of cell adhesion sites of the basement membrane

Collagen type IV forms a network in the basement membrane into which other constituents of the tissue are incorporated. It also provides cell-adhesion sites that are specifically recognized by cell-surface receptors, i.e., the integrins. Different from the ubiquitous sequential RGD adhesion motif found in most of the matrix proteins, in collagen type IV, the responsible binding sites for alpha1beta1 integrin have been identified as Asp461 of the two alpha1 chains and Arg461 of the alpha2 chain. Because of the heterotrimeric character of this collagen, the spatial geometry of the binding epitope depends not only on the triple-helical fold, but decisively even on the stagger of the chains. To investigate the effects of chain registration on the conformational properties and binding affinities of this adhesion epitope, two synthetic heterotrimeric collagen peptides consisting of the identical three chains were assembled by an artificial cystine knot in two different registers, i.e., in the most plausible alpha2alpha1alpha1' and less probable alpha1alpha2alpha1' chain alignment. A detailed conformational characterization of both trimers allowed to correlate their different binding affinities for alpha1beta1 integrin with the degree of local plasticity of the two different triple helices. Optimal local breathing of the rod-shaped collagens is apparently crucial for selective recognition by proteins interacting with these main components of the extracellular matrix.     

Inside Cover: Polarimetric imaging of biological tissues based on the indices of polarimetric purity (J. Biophotonics 4/2018)

The cover shows the image enhancement of biological tissues provided by the Indices of Polarimetric Purity (IPPs). By measuring the Mueller matrix of a biological sample, using an imaging polarimeter, the IPPs are calculated. They are polarimetric indicators providing further synthetization of depolarizing samples and leading to enhanced image contrast for some biological structures. Once the IPPs are calculated, a pseudo‐colouring technique is applied for higher visualization. Further details can be found in the article by Albert Van Eeckhout et al. ( e201700189 )

     

Targeting the NG2/CSPG4 proteoglycan retards tumour growth and angiogenesis in preclinical models of GBM and melanoma

Aberrant expression of the progenitor marker Neuron-glia 2 (NG2/CSPG4) or melanoma proteoglycan on cancer cells and angiogenic vasculature is associated with an aggressive disease course in several malignancies including glioblastoma multiforme (GBM) and melanoma. Thus, we investigated the mechanism of NG2 mediated malignant progression and its potential as a therapeutic target in clinically relevant GBM and melanoma animal models. Xenografting NG2 overexpressing GBM cell lines resulted in increased growth rate, angiogenesis and vascular permeability compared to control, NG2 negative tumours. The effect of abrogating NG2 function was investigated after intracerebral delivery of lentivirally encoded shRNAs targeting NG2 in patient GBM xenografts as well as in established subcutaneous A375 melanoma tumours. NG2 knockdown reduced melanoma proliferation and increased apoptosis and necrosis. Targeting NG2 in two heterogeneous GBM xenografts significantly reduced tumour growth and oedema levels, angiogenesis and normalised vascular function. Vascular normalisation resulted in increased tumour invasion and decreased apoptosis and necrosis. We conclude that NG2 promotes tumour progression by multiple mechanisms and represents an amenable target for cancer molecular therapy.     

Global diversity and distribution of aerobic anoxygenic phototrophs in the tropical and subtropical oceans

The aerobic anoxygenic phototrophic (AAP) bacteria are common in most marine environments but their global diversity and biogeography remain poorly characterized. Here, we analyzed AAP communities across 113 globally-distributed surface ocean stations sampled during the Malaspina Expedition in the tropical and subtropical ocean. By means of amplicon sequencing of the pufM gene, a genetic marker for this functional group, we show that AAP communities along the surface ocean were mainly composed of members of the Halieaceae (Gammaproteobacteria), which were adapted to a large range of environmental conditions, and of different clades of the Alphaproteobacteria, which seemed to dominate under particular circumstances, such as in the oligotrophic gyres. AAP taxa were spatially structured within each of the studied oceans, with communities from adjacent stations sharing more taxonomic similarities. AAP communities were composed of a large pool of rare members and several habitat specialists. When compared to the surface ocean prokaryotic and picoeukaryotic communities, it appears that AAP communities display an idiosyncratic global biogeographical pattern, dominated by selection processes and less influenced by dispersal limitation. Our study contributes to the understanding of how AAP communities are distributed in the horizontal dimension and the mechanisms underlying their distribution across the global surface ocean.     

Four drug-HAART in primary HIV-1 infection: clinical benefits and virologic parameters

BACKGROUND: From a theoretical standpoint, primary HIV infection (PHI) represents a great chance to modify the natural history of the disease. In this study we purposed a four drugs regimen with zidovudine, lamivudine, ritonavir and saquinavir to treat aggressively the infection and achieve a complete immune reconstitution. METHODS: This is an Italian multicentric open label study. Adult patients with PHI were eligible for the study if they met at least one clinical criterion and one laboratory criterion of the following. Clinical criteria: Signs and symptoms of acute retroviral syndrome within the past 70 days, exposure to HIV-1 within the last 3 months, a preceding negative antibody test within the past 6 months. Laboratory criteria: Detectable p24 antigen with neutralization in serum; detectable HIV-RNA in plasma; indeterminate Western blot test with negative or low positive value HIV antibody in ELISA test. RESULTS: Since April 1997 to April 1999 40 patients with PHI have been enrolled; 80% of this cohort referred symptoms related to acute antiretroviral syndrome. Treatment has been withdrawn in 17 patients (12 for intolerance, 3 for toxicity and 2 for failure). At baseline the mean CD4+ T cells count and CD4/CD8 ratio were 537 (range 55-1287) and 0.58 (range 0.1-1.03) and the mean plasma HIV-RNA level was 5.9 log copies/ml (range 3-7.15). Plasmatic HIV-1 RNA levels of all patients dropped below 200 copies/ml in 68% of patients at week 12, 81% at week 24, 93% after 12 months and 100% after 18 months. Immunological parameters have been improved and have achieved normal range since 6th month. CONCLUSIONS: A rapid virologic suppression and immunological reconstitution are associated with PHI therapy. However early treatment should be weighted against the potential disadvantages such as immediate adverse events (intolerance and drug toxicity) and long term manifestation (metabolic disorders).