Prognostic Significance of Deregulated Dicer Expression in Breast Cancer

Background

Dicer, an RNase III-type endonuclease, is the key enzyme involved in RNA interference and microRNA pathways. Aberrant expression of Dicer is reported in several human cancers. Our aim was to assess the prognostic role of Dicer in breast cancer.

Methods

The entire series comprised 666 invasive breast cancers (IBCs), 480 DCIS cases (397 associated with IBC and 83 pure DCIS) and 305 lymph node metastases. Cytoplasmic Dicer expression by immunohistochemistry was scored as negative (no staining) and positive (weak, moderate or strong staining).

Results

Dicer staining was assessable in 446 IBC, 128 DCIS and 101 lymph node metastases. Expression of Dicer was observed in 33% (145/446) of IBCs, 34% (44/128) of DCIS and 57% (58/101) of lymph node metastases. Dicer expression was increased in nodal metastases compared to primary tumours (p<0.001); and was associated with ER negativity (p<0.001), HER2 positivity (p<0.001), high Ki67 labeling index (p<0.001) and expression of basal-like biomarkers (p = 0.002). Dicer positivity was more frequent in the HER2 overexpressing (p<0.001) and basal-like (p = 0.002) subtypes compared to luminal A subtype. Dicer expression was associated with reduced overall survival (OS) on univariate analysis (p = 0.058) and remained an independent predictor of OS on multivariate analysis (HR 2.84, 95% CI 1.43–5.62, p = 0.003), with nodal status (HR 2.61, 95% CI 1.18–5.80, p = 0.018) and PR (HR 0.28, 95% CI 0.13–0.59, p = 0.001). Further, moderate or strong expression of Dicer was associated with improved disease-free survival in the HER2-overexpressing subtype compared to negative or weak expression (p = 0.038).

Conclusion

Deregulated Dicer expression is associated with aggressive tumour characteristics and is an independent prognostic factor for OS. Our findings suggest that Dicer is an important prognostic marker in breast cancer and that its prognostic role may be subtype specific.     

Sir2 deletion prevents lifespan extension in 32 long-lived mutants

Activation of Sir2 orthologs is proposed to increase lifespan downstream of dietary restriction. Here, we describe an examination of the effect of 32 different lifespan-extending mutations and four methods of DR on replicative lifespan (RLS) in the short-lived sir2Δ yeast strain. In every case, deletion of SIR2 prevented RLS extension; however, RLS extension was restored when both SIR2 and FOB1 were deleted in several cases, demonstrating that SIR2 is not directly required for RLS extension. These findings indicate that suppression of the sir2Δ lifespan defect is a rare phenotype among longevity interventions and suggest that sir2Δ cells senesce rapidly by a mechanism distinct from that of wild-type cells. They also demonstrate that failure to observe lifespan extension in a short-lived background, such as cells or animals lacking sirtuins, should be interpreted with caution.     

Hormone signaling linked to silkmoth sex pheromone biosynthesis involves Ca2+/calmodulin-dependent protein kinase II-mediated phosphorylation of the insect PAT family protein Bombyx mori lipid storage droplet protein-1 (BmLsd1)

Species-specific sex pheromones released by female moths to attract conspecific male moths are synthesized de novo in the pheromone gland (PG) via the fatty acid biosynthetic pathway. This pathway is regulated by a neurohormone termed pheromone biosynthesis activating neuropeptide (PBAN), a 33-amino acid peptide that originates in the subesophageal ganglion. In the silkmoth, Bombyx mori, cytoplasmic lipid droplets, which store the sex pheromone (bombykol) precursor fatty acid, accumulate in PG cells. PBAN stimulates lipolysis of the stored lipid droplet triacylglycerols (TAGs) and releases the precursor for final modification. PBAN exerts its physiological function via the PG cell-surface PBAN receptor, a G protein-coupled receptor that belongs to the neuromedin U receptor family. The PBAN receptor-mediated signal is transmitted via a canonical store-operated channel activation pathway utilizing Gq-mediated phospholipase C activation (Hull, J. J., Kajigaya, R., Imai, K., and Matsumoto, S. (2007) Biosci. Biotechnol. Biochem. 71, 1993-2001; Hull, J. J., Lee, J. M., Kajigaya, R., and Matsumoto, S. (2009) J. Biol. Chem. 284, 31200-31213; Hull, J. J., Lee, J. M., and Matsumoto, S. (2010) Insect Mol. Biol. 19, 553-566). Little, however, is known about the molecular components regulating TAG lipolysis in PG cells. In the current study we found that PBAN signaling involves phosphorylation of an insect PAT family protein named B. mori lipid storage droplet protein-1 (BmLsd1) and that BmLsd1 plays an essential role in the TAG lipolysis associated with bombykol production. Unlike mammalian PAT family perilipins, however, BmLsd1 activation is dependent on phosphorylation by B. mori Ca(2+)/calmodulin-dependent protein kinase II rather than protein kinase A.     

Recrudescent Infection Supports Hendra Virus Persistence in Australian Flying-Fox Populations

Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of recrudescence merits increased attention.     

Hydrogen production and uptake by pea nodules as affected by strains of Rhizobium leguminosarum

Hydrogen evolution from root nodules has been reported to make N₂ fixation by some legume-Rhizobium symbiotic systems inefficient. We have surveyed the extent of H₂ evolution and estimated relative efficiencies of nodules of Austrian winter peas formed by 15 strains of R. leguminosarum. Their rates of H₂ evolution in air were about 30% of the rates of H₂ evolution under an atmosphere in which N₂ was replaced by Ar. Relative efficiency values based on C₂H₂ reduction rates ranged from 0.55 to 0.80. With some of the strains, hydrogenase activities were demonstrated in intact nodules and in bacteroids, but the levels of activity were insufficient to recycle all the H₂ evolved by the nitrogenase system. In both intact nodules and bacteroids the hydrogenase is less sensitive to O₂ damage than the nitrogenase system, so H₂ uptake capacity was observed in intact nodules by suppressing the nitrogenase-dependent H₂ evolution with an atmosphere containing a high O₂ concentration, and in bacteroids by using aerobically prepared bacteroid suspensions. The hydrogenase activity of both was dependent on O₂ consumption. A K _mfor H₂ of near 4 M was determined in suspension of bacteroids from nodules formed by strains 128C53 and 128C56.     

A Randomized Trial Assessing the Safety and Immunogenicity of AS01 and AS02 Adjuvanted RTS,S Malaria Vaccine Candidates in Children in Gabon

Background

The malaria vaccine candidate antigen RTS,S includes parts of the pre-erythrocytic stage circumsporozoite protein fused to the Hepatitis B surface antigen. Two Adjuvant Systems are in development for this vaccine, an oil-in water emulsion – based formulation (AS02) and a formulation based on liposomes (AS01).

Methods & Principal Findings

In this Phase II, double-blind study ({"type":"clinical-trial","attrs":{"text":"NCT00307021","term_id":"NCT00307021"}}NCT00307021), 180 healthy Gabonese children aged 18 months to 4 years were randomized to receive either RTS,S/AS01_E or RTS,S/AS02_D, on a 0–1–2 month vaccination schedule. The children were followed-up daily for six days after each vaccination and monthly for 14 months. Blood samples were collected at 4 time-points. Both vaccines were well tolerated. Safety parameters were distributed similarly between the two groups. Both vaccines elicited a strong specific immune response after Doses 2 and 3 with a ratio of anti-CS GMT titers (AS02_D/AS01_E) of 0.88 (95% CI: 0.68–1.15) post-Dose 3. After Doses 2 and 3 of experimental vaccines, anti-CS and anti-HBs antibody GMTs were higher in children who had been previously vaccinated with at least one dose of hepatitis B vaccine compared to those not previously vaccinated.

Conclusions

RTS,S/AS01_E proved similarly as well tolerated and immunogenic as RTS,S/AS02_D, completing an essential step in the age de-escalation process within the RTS,S clinical development plan.

Trial Registration

ClinicalTrials.gov. {"type":"clinical-trial","attrs":{"text":"NCT00307021","term_id":"NCT00307021"}}NCT00307021     

Early Events following Experimental Infection with Peste-Des-Petits Ruminants Virus Suggest Immune Cell Targeting

Peste-des-petits ruminants virus (PPRV) is a viral pathogen that causes a devastating plague of small ruminants. PPRV is an economically significant disease that continues to be a major obstacle to the development of sustainable agriculture across the developing world. The current understanding of PPRV pathogenesis has been heavily assumed from the closely related rinderpest virus (RPV) and other morbillivirus infections alongside data derived from field outbreaks. There have been few studies reported that have focused on the pathogenesis of PPRV and very little is known about the processes underlying the early stages of infection. In the present study, 15 goats were challenged by the intranasal route with a virulent PPRV isolate, Côte d’Ivoire ’89 (CI/89) and sacrificed at strategically defined time-points post infection to enable pre- and post-mortem sampling. This approach enabled precise monitoring of the progress and distribution of virus throughout the infection from the time of challenge, through peak viraemia and into a period of convalescence. Observations were then related to findings of previous field studies and experimental models of PPRV to develop a clinical scoring system for PPRV. Importantly, histopathological investigations demonstrated that the initial site for virus replication is not within the epithelial cells of the respiratory mucosa, as has been previously reported, but is within the tonsillar tissue and lymph nodes draining the site of inoculation. We propose that virus is taken up by immune cells within the respiratory mucosa which then transport virus to lymphoid tissues where primary virus replication occurs, and from where virus enters circulation. Based on these findings we propose a novel clinical scoring methodology for PPRV pathogenesis and suggest a fundamental shift away from the conventional model of PPRV pathogenesis.     

Decolorization of reactive dyes by <Emphasis Type="Italic">Clostridium bifermentans</Emphasis> SL186 isolated from contaminated soil

Decolorization of textile reactive azo dyes by a strain of bacteria (SL186) isolated from a contaminated site was investigated. SL186 was identified as Clostridium bifermentans by phenotypic characterization and 16S rDNA sequence comparison. Under anaerobic conditions, SL186 had decolorized the dyes Reactive Red 3B-A, Reactive Black 5, and Reactive Yellow 3G-P by over 90% after 36 h post-inoculation. The bacterium retained decolorizing activity over a wide range of pH values (6–12), with peak activity at pH 10. Additionally, SL186 decolorized a relatively high concentration of Reactive Red 3B-A dye (1,000 ppm) by over 80% and raw industrial effluent effectively. The addition of glucose increased the decolorization rate a little. Spectrophotometric analyses of the reactive dyes showed no distinct peak indicating aromatic amines. However, a new peak was detected between 300 and 450 nm from the decolorized raw industrial effluent. These results suggest that C. bifermentans SL186 is a suitable bacterium for the biological processing of dye-containing wastewater.     

CD44 regulates hepatocyte growth factor-mediated vascular integrity. Role of c-Met, Tiam1/Rac1, dynamin 2, and cortactin

The preservation of vascular endothelial cell (EC) barrier integrity is critical to normal vessel homeostasis, with barrier dysfunction being a feature of inflammation, tumor angiogenesis, atherosclerosis, and acute lung injury. Therefore, agents that preserve or restore vascular integrity have important therapeutic implications. In this study, we explored the regulation of hepatocyte growth factor (HGF)-mediated enhancement of EC barrier function via CD44 isoforms. We observed that HGF promoted c-Met association with CD44v10 and recruitment of c-Met into caveolin-enriched microdomains (CEM) containing CD44s (standard form). Treatment of EC with CD44v10-blocking antibodies inhibited HGF-mediated c-Met phosphorylation and c-Met recruitment to CEM. Silencing CD44 expression (small interfering RNA) attenuated HGF-induced recruitment of c-Met, Tiam1 (a Rac1 exchange factor), cortactin (an actin cytoskeletal regulator), and dynamin 2 (a vesicular regulator) to CEM as well as HGF-induced trans-EC electrical resistance. In addition, silencing Tiam1 or dynamin 2 reduced HGF-induced Rac1 activation, cortactin recruitment to CEM, and EC barrier regulation. We observed that both HGF- and high molecular weight hyaluronan (CD44 ligand)-mediated protection from lipopolysaccharide-induced pulmonary vascular hyperpermeability was significantly reduced in CD44 knock-out mice, thus validating these in vitro findings in an in vivo murine model of inflammatory lung injury. Taken together, these results suggest that CD44 is an important regulator of HGF/c-Met-mediated in vitro and in vivo barrier enhancement, a process with essential involvement of Tiam1, Rac1, dynamin 2, and cortactin.