Fibulin-5, an integrin-binding matricellular protein: its function in development and disease

Interactions between the extracellular matrix (ECM) and cells are critical in embryonic development, tissue homeostasis, physiological remodeling, and tumorigenesis. Matricellular proteins, a group of ECM components, mediate cell-ECM interactions. One such molecule, Fibulin-5 is a 66-kDa glycoprotein secreted by various cell types, including vascular smooth muscle cells (SMCs), fibroblasts, and endothelial cells. Fibulin-5 contributes to the formation of elastic fibers by binding to structural components including tropoelastin and fibrillin-1, and to cross-linking enzymes, aiding elastic fiber assembly. Mice deficient in the fibulin-5 gene (Fbln5) exhibit systemic elastic fiber defects with manifestations of loose skin, tortuous aorta, emphysematous lung and genital prolapse. Although Fbln5 expression is down-regulated after birth, following the completion of elastic fiber formation, expression is reactivated upon tissue injury, affecting diverse cellular functions independent of its elastogenic function. Fibulin-5 contains an evolutionally conserved arginine-glycine-aspartic acid (RGD) motif in the N-terminal region, which mediates binding to a subset of integrins, including α5β1, αvβ3, and αvβ5. Fibulin-5 enhances substrate attachment of endothelial cells, while inhibiting migration and proliferation in a cell type- and context-dependent manner. The antagonistic function of fibulin-5 in angiogenesis has been demonstrated in vitro and in vivo; fibulin-5 may block angiogenesis by inducing the anti-angiogenic molecule thrompospondin-1, by antagonizing VEGF165-mediated signaling, and/or by antagonizing fibronectin-mediated signaling through directly binding and blocking the α5β1 fibronectin receptor. The overall effect of fibulin-5 on tumor growth depends on the balance between the inhibitory property of fibulin-5 on angiogenesis and the direct effect of fibulin-5 on proliferation and migration of tumor cells. However, the effect of tumor-derived versus host microenvironment-derived fibulin-5 remains to be evaluated

A genetic cause of Alzheimer disease: mechanistic insights from Down syndrome

Down syndrome, caused by an extra copy of chromosome 21, is associated with a greatly increased risk of early onset Alzheimer disease. It is thought that this risk is conferred by the presence of three copies of the gene encoding amyloid precursor protein (APP), an Alzheimer risk factor, although the possession of extra copies of other chromosome 21 genes may also play a role. Further study of the mechanisms underlying the development of Alzheimer disease in Down syndrome could provide insights into the mechanisms that cause dementia in the general population

Novel therapeutic mechanisms determine the effectiveness of lipid-core nanocapsules on melanoma models

Carine C Drewes,1,* Luana A Fiel,2,* Celina G Bexiga,1 Ana Carolina C Asbahr,3 Mayara K Uchiyama,4 Bruno Cogliati,5 Koiti Araki,4 Sílvia S Guterres,2,3 Adriana R Pohlmann,2,3,6 Sandra P Farsky1 1Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, 2Postgraduate Program in Pharmaceutical Sciences, Federal University of Rio Grande do Sul, Porto Alegre, 3Postgraduate Program in Pharmaceutical Nanotechnology, Federal University of Rio Grande do Sul, Porto Alegre, 4Department of Fundamental Chemistry, Institute of Chemistry, 5Department of Pathology, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, 6Department of Organic Chemistry, Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil *These authors contributed equally to this work Abstract: Melanoma is a severe metastatic skin cancer with poor prognosis and no effective treatment. Therefore, novel therapeutic approaches using nanotechnology have been proposed to improve therapeutic effectiveness. Lipid-core nanocapsules (LNCs), prepared with poly(ε-caprolactone), capric/caprylic triglyceride, and sorbitan monostearate and stabilized by polysorbate 80, are efficient as drug delivery systems. Here, we investigated the effects of acetyleugenol-loaded LNC (AcE-LNC) on human SK-Mel-28 melanoma cells and its therapeutic efficacies on melanoma induced by B16F10 in C57B6 mice. LNC and AcE-LNC had z-average diameters and zeta potential close to 210 nm and -10.0 mV, respectively. CytoViva® microscopy images showed that LNC and AcE-LNC penetrated into SK-Mel-28 cells, and remained in the cytoplasm. AcE-LNC in vitro treatment (18–90×109 particles/mL; 1 hour) induced late apoptosis and necrosis; LNC and AcE-LNC (3–18×109 particles/mL; 48 hours) treatments reduced cell proliferation and delayed the cell cycle. Elevated levels of nitric oxide were found in supernatant of LNC and AcE-LNC, which were not dependent on nitric oxide synthase expressions. Daily intraperitoneal or oral treatment (days 3–10 after tumor injection) with LNC or AcE-LNC (1×1012 particles/day), but not with AcE (50 mg/kg/day, same dose as AcE-LNC), reduced the volume of the tumor; nevertheless, intraperitoneal treatment caused toxicity. Oral LNC treatment was more efficient than AcE-LNC treatment. Moreover, oral treatment with nonencapsulated capric/caprylic triglyceride did not inhibit tumor development, implying that nanocapsule supramolecular structure is important to the therapeutic effects. Together, data herein presented highlight the relevance of the supramolecular structure of LNCs to toxicity on SK-Mel-28 cells and to the therapeutic efficacy on melanoma development in mice, conferring novel therapeutic mechanisms to LNC further than a drug delivery system. Keywords: capric/caprylic triglycerides, mice, acetyleugenol, B16F10 cells, SK-Mel-28, nitric oxide, cell proliferation, nanotoxicolog

Role of poly(ε-caprolactone) lipid-core nanocapsules on melanoma–neutrophil crosstalk

Carine C Drewes,1 Aline de CS Alves,2,3 Cristina B Hebeda,1 Isabela Copetti,2,3 Silvana Sandri,1 Mayara K Uchiyama,4 Koiti Araki,4 Silvia S Guterres,2 Adriana R Pohlmann,2,3 Sandra H Farsky1 1Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, 2Postgraduate Program in Pharmaceutical Sciences, 3Department of Organic Chemistry, Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre, 4Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil Abstract: Metastatic melanoma is an aggressive cancer with increasing incidence and limited therapies in advanced stages. Systemic neutrophilia or abundant neutrophils in the tumor contribute toward its worst prognosis, and the interplay of cancer and the immune system has been shown in tumor development and metastasis. We recently showed the in vivo efficacy of poly(ε-caprolactone) lipid-core nanocapsule (LNC) or LNC loaded with acetyleugenol (AcE-LNC) to treat B16F10-induced melanoma in mice. In this study, we investigated whether LNC or AcE-LNC toxicity could involve modifications on crosstalk of melanoma cells and neutrophils. Therefore, melanoma cells (B16F10) were pretreated with vehicle, LNC, AcE or AcE-LNC for 24 h, washed and, further, cocultured for 18 h with peritoneal neutrophils obtained from C57Bl/6 mice. Melanoma cells were able to internalize the LNC or AcE-LNC after 2 h of incubation. LNC or AcE-LNC pretreatments did not cause melanoma cells death, but led melanoma cells to be more susceptible to death in serum deprivation or hypoxia or in the presence of neutrophils. Interestingly, the production of reactive oxygen species (ROS), which causes cell death, was increased by neutrophils in the presence of LNC- and AcE-LNC-pretreated melanoma cells. LNC or AcE-LNC treatments reduced the concentration of transforming growth factor-β (TGF-β) in the supernatant of melanoma cells, a known factor secreted by cancer cells to induce pro-tumoral actions of neutrophils in the tumor microenvironment. In addition, we found reduced levels of pro-tumoral chemical mediators VEGF, arginase-1, interleukin-10 (IL-10) and matrix metalloproteinase-9 (MMP-9) in the supernatant of LNC or AcE-LNC-pretreated melanoma cells and cocultured with neutrophils. Overall, our data show that the uptake of LNC or AcE-LNC by melanoma cells affects intracellular mechanisms leading to more susceptibility to death and also signals higher neutrophil antitumoral activity. Keywords: hypoxia, serum deprivation, apoptosis, coculture, tumor microenvironment, LNC, acetyleugenol, intravital microscop

Factors associated with sexual risk behaviors with non-steady partners and lack of recent HIV testing among German men who have sex with men in steady relationships: results from a cross-sectional internet survey

Background: Recent evidence suggests that the majority of HIV transmissions among men who have sex with men (MSM) occur between steady partners. We sought to determine factors associated with HIV transmission risks in steady partnerships. Methods: Data is from the German cross-sectional 2013 Gay Men and AIDS survey. The study population was HIV-negative or untested men reporting a steady partnership and at least one non-steady anal sex partner in the previous year. Bivariate and multivariate logistic regression was used to determine which of several independent variables best predicted both unprotected anal intercourse (UAI) with a non-steady partner and lack of HIV testing in the past year (high-risk outcome group). Results: The study population consisted of 1731 men. Among individuals in the outcome group (n = 271), 67 % reported UAI with a non-steady partner of unknown status and 9 % reported UAI with a non-steady HIV-positive partner in the past 12 months; 55 % considered themselves to be at low risk for HIV acquisition. In multivariate analyses (n = 1304), participants were statistically more likely to belong to the outcome group if they reported UAI with their steady partner in the past year (OR = 2.21), did not know their steady partner’s HIV status (OR = 1.98), or agreed that condoms were disruptive during sex (OR = 3.82 (strongly agree), OR = 2.19 (agree)). Participants were less likely to belong to the outcome group if they were out to their primary doctor (OR = 0.54), were well-educated about post-exposure prophylaxis (OR = 0.46), had sought information on HIV in the past year and kept condoms in an accessible place (OR = 0.20), or believed that insisting on condoms would lead partners to assume they were HIV-negative (OR = 0.20). Participants in the outcome group were more likely to say they would use HIV home tests (OR = 1.58) or pre-exposure prophylaxis (OR = 2.11). Conclusions: Based on our results, we reflect on HIV prevention measures that should be improved in order to better target behaviors that may lead to HIV transmission between MSM in steady relationships. In particular, we highlight the need for multifaceted interventions focusing not only on members of the at-risk community themselves, but on communities as a whole