Comparative Analysis of Patient-Specific Aortic Dissections through Computational Fluid Dynamics Suggests Increased Likelihood of Degeneration in Partially Thrombosed False Lumen.

Aortic dissection is a life-threatening vascular disease associated with high rates of morbidity and mortality, especially in medically underserved communities. Understanding patients' blood flow patterns is pivotal for informing evidence-based treatment as they greatly influence the disease outcome. The present study investigates the flow patterns in the false lumen of three aorta dissections (fully perfused, partially thrombosed, and fully thrombosed) in the chronic phase, and compares them to a healthy aorta. Three-dimensional geometries of aortic true and false lumens (TLs and FLs) are reconstructed through an ad hoc developed and minimally supervised image analysis procedure. Computational fluid dynamics (CFD) is performed through a finite volume unsteady Reynolds-averaged Navier-Stokes approach assuming rigid wall aortas, Newtonian and homogeneous fluid, and incompressible flow. In addition to flow kinematics, we focus on time-averaged wall shear stress and oscillatory shear index that are recognized risk factors for aneurysmal degeneration. Our analysis shows that partially thrombosed dissection is the most prone to false lumen degeneration. In all dissections, the arteries connected to the false lumen are generally poorly perfused. Further, both true and false lumens present higher turbulence levels than the healthy aorta, and critical stagnation points. Mesh sensitivity and a thorough comparison against literature data together support the reliability of the CFD methodology. Image-based CFD simulations are efficient tools to assess the possibility of aortic dissection to lead to aneurysmal degeneration, and provide new knowledge on the hemodynamic characteristics of dissected versus healthy aortas. Similar analyses should be routinely included in patient-specific hemodynamics investigations, to plan and design tailored therapeutic strategies, and to timely assess their effectiveness.

Co-targeting leukemia-initiating cells and leukemia bulk leads to disease eradication.

According to a hierarchical model, targeting leukemia-initiating cells (LICs) was speculated to achieve complete remission (CR) or cure. Nonetheless, increasing evidence emphasized the plasticity of differentiated blasts undergoing interconversion into LICs. We exploited murine models of acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia driven by the promyelocytic leukemia/retinoic acid receptor (PML-RARα) oncofusion protein, which recruits histone deacetylase (HDAC)-containing complexes. We studied APLs with different LIC frequencies and investigated the effect of two HDAC inhibitors: valproic acid (VPA), with relative selectivity towards class I HDAC enzymes and vorinostat/suberoylanilide hydroxamic acid (SAHA) (pan-HDAC inhibitor) in combination with all-trans retinoic acid (ATRA), on the bulk APL cells and APL LICs. Indeed, we found that while VPA differentiates the bulk APL cells, SAHA selectively targets LICs. ATRA + VPA + SAHA combination efficiently induced CR in an APL model with lower LIC frequency. Substituting ATRA with synthetic retinoids as etretinate which promotes APL differentiation without downregulating PML/RARα compromised the therapeutic benefit of ATRA + VPA + SAHA regimen. Altogether, our study emphasizes the therapeutic power of co-targeting the plasticity and heterogeneity of cancer -herein demonstrated by tackling LICs and bulk leukemic blasts - to achieve and maintain CR.

Evaluation of long-term outcome and prognostic factors of feline squamous cell carcinomas treated with photodynamic therapy using liposomal phosphorylated meta-tetra(hydroxylphenyl)chlorine.

OBJECTIVES: The aim of this study was to evaluate the efficacy, long-term outcome and prognostic factors of feline squamous cell carcinoma (SCC) treated with photodynamic therapy (PDT). METHODS: Cats with histologically verified SCC of the head and neck received an intravenous injection of liposomal phosphorylated meta-tetra(hydroxylphenyl)chlorine (mTHPC) and 4 h later 652 nm light was delivered by a diode laser. One group received ⩽10 J/cm2, the other 20 J/cm2. Tumour response and duration were analysed with stage, tumour diameter, location and treatment intensity as prognostic factors. RESULTS: In total, 63 lesions in 38 cats underwent treatment with ⩽10 J/cm2 (n = 22) and 20 J/cm2 (n = 41). Overall response rate was 84% (complete remission 61%, partial remission 22%) with a mean progression-free interval of 35 months (median not reached) and a median overall survival time of 40 months (95% confidence interval 33-47). With regard to tumour stage, invasiveness yielded a highly significant worse outcome ( P <0.017). All patients with invasive tumours showed progression at less than 6 months. Larger lesions were associated with inferior control and treatment intensity, and tumour location did not influence response and duration. CONCLUSIONS AND RELEVANCE: PDT using a systemic photosensitiser leads to excellent long-term tumour control in the majority of cats. However, invasive and large tumours had a clearly inferior outcome, even if treated with the higher-dose intensity. This suggests that advanced lesions are not indications for PDT.

A dual role for Hdac1: oncosuppressor in tumorigenesis, oncogene in tumor maintenance.

Aberrant recruitment of histone deacetylases (HDACs) by the oncogenic fusion protein PML-RAR is involved in the pathogenesis of acute promyelocytic leukemia (APL). PML-RAR, however, is not sufficient to induce disease in mice but requires additional oncogenic lesions during the preleukemic phase. Here, we show that knock-down of Hdac1 and Hdac2 dramatically accelerates leukemogenesis in transgenic preleukemic mice. These events are not restricted to APL because lymphomagenesis driven by deletion of p53 or, to a lesser extent, by c-myc overexpression, was also accelerated by Hdac1 knock-down. In the preleukemic phase of APL, Hdac1 counteracts the activity of PML-RAR in (1) blocking differentiation; (2) impairing genomic stability; and (3) increasing self-renewal in hematopoietic progenitors, as all of these events are affected by the reduction in Hdac1 levels. This led to an expansion of a subpopulation of PML-RAR-expressing cells that is the major source of leukemic stem cells in the full leukemic stage. Remarkably, short-term treatment of preleukemic mice with an HDAC inhibitor accelerated leukemogenesis. In contrast, knock-down of Hdac1 in APL mice led to enhanced survival duration of the leukemic animals. Thus, Hdac1 has a dual role in tumorigenesis: oncosuppressive in the early stages, and oncogenic in established tumor cells.

SILAC-based proteomic analysis to dissect the "histone modification signature" of human breast cancer cells.

In living cells, the N-terminal tails of core histones, the proteinaceous component of nucleosomes, are subjected to a range of covalent post-translational modifications (PTMs), which have specific roles in modulating chromatin structure and function. A growing body of evidence suggests that deregulation of histone modification patterns, upstream or downstream of DNA methylation, is a critical event in cancer initiation and progression. However, a comprehensive description of how histone modifications, singly or in combination, is disrupted in transformed cells is missing; consequently the issue whether and how specific changes in histone PTMs patterns correlate to particular tumor features is still elusive. In the present study, we focused on human breast cancer and comprehensively analyzed PTMs on histone H3 and H4 from four cancer cell lines (MCF7, MDA-MB231, MDA-MB453 and T-47D), in comparison with normal epithelial breast cells. We performed high-resolution mass spectrometry analysis of histones, in combination with stable isotope labeling with amino acids in cell culture (SILAC), to quantitatively track the modification changes in cancer cells, as compared to their normal counterpart. Our investigation focuses on lysine acetylation and methylation on fourteen distinct sites in H3 and H4. We observed significant changes for several modifications in cancer cells: while in a few cases those modifications had been previously described as a hallmark of human tumors, we could identify novel modifications, whose abundance is significantly altered in breast cancer cells. Overall, these modifications may represent part of a "breast cancer-specific epigenetic signature", with implications in the characterization of histone-related biomarkers. This work demonstrates that SILAC-based proteomics is a powerful tool to study qualitatively and quantitatively histone PTMs patterns, contributing significantly to the comprehension of epigenetic phenomena in cancer biology.

Hyperglycaemia but not hyperlipidaemia decreases serum amylase and increases neutrophils in the exocrine pancreas of cats.

The goal of the study was to determine whether hyperglycaemia or hyperlipidaemia causes pancreatitis in cats and to assess the effect of excess serum glucose and lipids on amylase and lipase activity. Ten-day hyperglycaemic and hyperlipidaemic clamps were carried out in five and six healthy cats, respectively. Ten healthy cats received saline and served as controls. The activity of amylase was below the normal range in 4 of 5 hyperglycaemic cats by day 10. The activity of lipase did not vary in any of the cats. Samples of exocrine pancreas were normal on histological examination, but the number of tissue neutrophils was increased in hyperglycaemic cats (P<0.05). In a retrospective study 14 of 40 (35%) cats with naturally occurring diabetes mellitus had amylase activities below the reference range at the time of admission. Amylase activities normalised within 1 week of insulin therapy and subsequent glycaemic control. Lipase activity was increased in 26 of 40 (65%) diabetic cats and remained elevated despite glycaemic control. In conclusion, hyperglycaemia, but not hyperlipidaemia, increases pancreatic neutrophils in cats. However, because the histological morphology of the exocrine pancreas was normal, hyperglycaemia may play only a minor role in the pathogenesis of pancreatitis. Low amylase activities in diabetic cats may reflect an imbalance in glucose metabolism rather than pancreatitis.

Enhanced antitumor therapy by inhibition of p21waf1 in human malignant mesothelioma.

PURPOSE: The p21 cyclin-dependent kinase inhibitor was frequently expressed in human malignant pleural mesothelioma (MPM) tissues as well as cell lines. Recent data indicate that p21 keeps tumor cells alive after DNA damage, favoring a survival advantage. In this study, we assessed the possibility of p21 suppression as a therapeutic target for MPM. EXPERIMENTAL DESIGN: We established two different MPM-derived (from H28 and H2052 cells) subclones using vector-based short hairpin RNA (shRNA). Then, chemosensitivity against low doses of antineoplastic DNA-damaging agents was investigated by colony formation assays, and furthermore, the type of cell response induced by these drugs was analyzed. To examine the effect of p21 shRNA on chemosensitivity in vivo, tumor formation assays in nude mice were done. RESULTS: In colony formation assay, the IC50 of doxorubicin was 33 +/- 3.0 nmol/L in p21 shRNA-transfected cells with respect to 125 +/- 10 nmol/L of control vector-transfected cells. This enhancement of growth inhibition was achieved by converting a senescence-like growth arrest to apoptosis in response to doxorubicin, etoposide, and CPT11. In the in vivo assays, CPT11 and loss-of-expression of p21 in combination led to considerable suppression of tumor growth associated with a substantially enhanced apoptotic response, whereas CPT11 alone was ineffective at inducing these responses. CONCLUSIONS: These results indicated that p21 might play an important role in chemosensitivity to anticancer agents, and the suppression of its expression might be a potential therapeutic target for MPM.

Semaphorin3A signaling controls Fas (CD95)-mediated apoptosis by promoting Fas translocation into lipid rafts.

Semaphorins and their receptors (plexins) have pleiotropic biologic functions, including regulation of immune responses. However, the role of these molecules inside the immune system and the signal transduction mechanism(s) they use are largely unknown. Here, we show that Semaphorin3A (Sema3A) triggers a proapoptotic program that sensitizes leukemic T cells to Fas (CD95)-mediated apoptosis. We found that Sema3A stimulation provoked Fas translocation into lipid raft microdomains before binding with agonistic antibody or FasL (CD95L). Disruption of lipid rafts reduced sensitivity to Fas-mediated apoptosis in the presence of Sema3A. Furthermore, we show that plexin-A1, together with Sema3A-binding neuropilin-1, was rapidly incorporated into membrane rafts after ligand stimulation, resulting in the transport of actin-linking proteins into Fas-enriched rafts. Cells expressing a dominant-negative mutant of plexin-A1 did not show Fas clustering and apoptosis on Sema3A/Fas costimulation. This work identifies a novel biologic function of semaphorins and presents an unexpected signaling mechanism linking semaphorin to the tumor necrosis factor family receptors.

Neuronal semaphorins regulate a primary immune response.

Semaphorins are involved in a wide range of biological processes, including axon guidance, neuronal migration, angiogenesis, cardio- and osteo-genesis. Recently they have also been found to be important for immune response. Sema3A reduces the activation of T cells through its cell-surface receptors, including members of the neuropilin and plexin families. By contrast, Sema4D (CD100), which is expressed on the surface of T, B and dendritic cells, increases B cell and dendritic cell function using either plexin B1 or CD72 as receptors. The transmembrane protein Sema4A is involved in the activation of immune cells through interactions with Tim-2. Emerging evidence also indicates that additional semaphorins and related molecules seem to function in the reciprocal stimulation of T cells and antigen-presenting cells (APCs). This paper discusses the functions of these semaphorins in the immune system, focusing on their roles in T cell-APC interactions.

Semaphorin-3A is expressed by tumor cells and alters T-cell signal transduction and function.

An important aspect of tumor progression is the ability of cancer cells to escape detection and clearance by the immune system. Recent studies suggest that several tumors express soluble factors interfering with the immune response. Here, we show that semaphorin-3A (Sema-3A), a secreted member of the semaphorin family involved in axonal guidance, organogenesis, and angiogenesis, is highly expressed in several tumor cells. Conditioned media of Sema-3A-transfected COS-7 cells or human recombinant Sema-3A inhibited primary human T-cell proliferation and cytokines production under anti-CD3 plus anti-CD28 stimulating conditions. Sema-3A also inhibited the activation of nonspecific cytotoxic activity in mixed lymphocyte culture (MLC), as measured against K-562 cells. In contrast, suppression of Sema-3A in tumor cells with a small interfering RNA (siRNA) augmented T-cell activation. The inhibitory effect of Sema-3A in T cells is mediated by blockade of Ras/mitogen-activated protein kinase (MAPK) signaling pathway. The presence of Sema-3A increased the activation of the Ras family small GTPase Rap1 and introduction of the dominant-negative mutant of Rap1 (Rap1N17) blunted the immunoinhibitory effects of Sema-3A. These results suggest that Sema-3A inhibits primary T-cell activation and imply that it can contribute to the T-cell dysfunction in the tumor microenvironment.

FLIP overexpression inhibits death receptor-induced apoptosis in malignant mesothelial cells.

Tumors have developed several forms of resistance to receptor-induced cell death. Here, we show that malignant mesothelial (MM) cell lines as well as primary MM cells and normal mesothelial (NM) cells express Fas and TNF-related apoptosis-inducing ligand (TRAIL) receptors DR4 and DR5. We found that, although Fas expression levels are comparable, only MM cells are resistant to cell death. Furthermore, MM cells show resistance to TRAIL-induced apoptosis. Caspase-8 (FLICE) is not activated by death receptors triggering in malignant cells whereas it is well activated by nonreceptor stimuli, such as UV radiation. We found that FLIP (FLICE-Inhibitory Protein) is constitutively expressed in all MM cell lines and is more expressed in primary MM cells than in NM cells. Knockdown of FLIP expression in MM cell lines, by a FLIPsiRNA, re-established the normal response to apoptosis induced by Fas or DR4/DR5, which was blocked by pretreatment with the caspase-8 inhibitor z-IETD-fmk. These results indicate that MM cells develop an intrinsic resistance to apoptosis induced by death receptors upregulating the expression of the antiapoptotic protein c-FLIP.

Role of nitric oxide concentrations on human sperm motility.

Nitric oxide (NO) is a free radical generated from the oxidation of L-arginine to L-citrulline by 3 isoforms of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent NO synthases. Several data suggest a relevant role in sperm cell pathophysiology, but any conclusive data on its role in spermatozoa motility are still lacking. In the present study, we have correlated NO concentration in semen and kinetic features of sperm cells from normozoospermic fertile donors and infertile patients affected by idiopathic asthenozoospermia. Normozoospermic fertile men exhibited NO concentrations that were significantly lower than those of asthenozoospermic infertile men. A significant linear negative correlation was evident between NO concentration and percentage of total sperm motility. A further significant linear negative correlation was found between NO concentration and spermatozoa kinetic characteristics determined by a computerized analysis (curvilinear and straight progressive velocity). These data suggest that the overproduction of this free radical and the consequent excessive exposure to oxidative conditions have a potential pathogenetic implication in the reduction of sperm motility. The positive role played by NO in spermatozoa capacitation leads us to speculate that such paradoxical involvement in both pathologic and physiologic processes depends on the alternative redox state and relative level of NO.