Understanding the function of the tumor microenvironment,and compounds from marine organisms for breast cancer therapy

The pathology and physiology of breast cancer(BC),including metastasis,and drug resistance,is driven by multiple signaling pathways in the tumor microenvironment(TME),which hamper antitumor immunity.Recently,long non-coding RNAs have been reported to mediate pathophysiological developments such as metastasis as well as immune suppression within the TME.Given the complex biology of BC,novel personalized therapeutic strategies that address its diverse pathophysiologies are needed to improve clinical outcomes.In this review,we describe the advances in the biology of breast neoplasia,including cellular and molecular biology,heterogeneity,and TME.We review the role of novel molecules such as long non-coding RNAs in the pathophysiology of BC.Finally,we provide an up-to-date overview of anticancer compounds extracted from marine microorganisms,crustaceans,and fishes and their synergistic effects in combination with other anticancer drugs.Marine compounds are a new discipline of research in BC and offer a wide range of anti-cancer effects that could be harnessed to target the various pathways involved in BC development,thus assisting current therapeutic regimens.     

Decoding the genome beyond sequencing: the new phase of genomic research

While our understanding of gene-based biology has greatly improved, it is clear that the function of the genome and most diseases cannot be fully explained by genes and other regulatory elements. Genes and the genome represent distinct levels of genetic organization with their own coding systems; Genes code parts like protein and RNA, but the genome codes the structure of genetic networks, which are defined by the whole set of genes, chromosomes and their topological interactions within a cell. Accordingly, the genetic code of DNA offers limited understanding of genome functions. In this perspective, we introduce the genome theory which calls for the departure of gene-centric genomic research. To make this transition for the next phase of genomic research, it is essential to acknowledge the importance of new genome-based biological concepts and to establish new technology platforms to decode the genome beyond sequencing.     

Tobacco plastidial thioredoxins as modulators of recombinant protein production in transgenic chloroplasts

Thioredoxins (Trxs) are small ubiquitous disulphide proteins widely known to enhance expression and solubility of recombinant proteins in microbial expression systems. Given the common evolutionary heritage of chloroplasts and bacteria, we attempted to analyse whether plastid Trxs could also act as modulators of recombinant protein expression in transgenic chloroplasts. For that purpose, two tobacco Trxs (m and f) with different phylogenetic origins were assessed. Using plastid transformation, we assayed two strategies: the fusion and the co-expression of Trxs with human serum albumin (HSA), which was previously observed to form large protein bodies in tobacco chloroplasts. Our results indicate that both Trxs behave similarly as regards HSA accumulation, although they act differently when fused or co-expressed with HSA. Trxs-HSA fusions markedly increased the final yield of HSA (up to 26% of total protein) when compared with control lines that only expressed HSA; this increase was mainly caused by higher HSA stability of the fused proteins. However, the fusion strategy failed to prevent the formation of protein bodies within chloroplasts. On the other hand, the co-expression constructs gave rise to an absence of large protein bodies although no more soluble HSA was accumulated. In these plants, electron micrographs showed HSA and Trxs co-localization in small protein bodies with fibrillar texture, suggesting a possible influence of Trxs on HSA solubilization. Moreover, the in vitro chaperone activity of Trx m and f was demonstrated, which supports the hypothesis of a direct relationship between Trx presence and HSA aggregates solubilization in plants co-expressing both proteins.     

A phosphate-regulated promoter for fine-tuned and reversible overexpression in Ostreococcus: application to circadian clock functional analysis

BACKGROUND: The green picoalga Ostreococcus tauri (Prasinophyceae), which has been described as the smallest free-living eukaryotic organism, has minimal cellular ultra-structure and a very small genome. In recent years, O. tauri has emerged as a novel model organism for systems biology approaches that combine functional genomics and mathematical modeling, with a strong emphasis on light regulated processes and circadian clock. These approaches were made possible through the implementation of a minimal molecular toolbox for gene functional analysis including overexpression and knockdown strategies. We have previously shown that the promoter of the High Affinity Phosphate Transporter (HAPT) gene drives the expression of a luciferase reporter at high and constitutive levels under constant light. METHODOLOGY/PRINCIPAL FINDINGS: Here we report, using a luciferase reporter construct, that the HAPT promoter can be finely and reversibly tuned by modulating the level and nature of phosphate in culture medium. This HAPT regulation was additionally used to analyze the circadian clock gene Time of Cab expression 1 (TOC1). The phenotype of a TOC1ox/CCA1:Luc line was reverted from arrhythmic to rhythmic simply by adding phosphate to the culture medium. Furthermore, since the time of phosphate injection had no effect on the phase of CCA1:Luc expression, this study suggests further that TOC1 is a central clock gene in Ostreococcus. CONCLUSIONS/PERSPECTIVES: We have developed a phosphate-regulated expression system that allows fine gene function analysis in Ostreococcus. Recently, there has been a growing interest in microalgae as cell factories. This non-toxic phosphate-regulated system may prove useful in tuning protein expression levels quantitatively and temporally for biotechnological applications.     

Tuning the properties of elastin mimetic hybrid copolymers via a modular polymerization method

We have synthesized elastin mimetic hybrid polymers (EMHPs) via the step-growth polymerization of azide-functionalized poly(ethylene glycol) (PEG) and alkyne-terminated peptide (AKAAAKA)(2) (AK2) that is abundant in the cross-linking domains of the natural elastin. The modular nature of our synthesis allows facile adjustment of the peptide sequence to modulate the structural and biological properties of EMHPs. Therefore, EMHPs containing cell-binding domains (CBDs) were constructed from α,ω-azido-PEG and two types of alkyne-terminated AK2 peptides with sequences of DGRGX(AKAAAKA)(2)X (AK2-CBD1) and X(AKAAAKA)(2)XGGRGDSPG (AK2-CBD2, X = propargylglycine) via a step-growth, click coupling reaction. The resultant hybrid copolymers contain an estimated five to seven repeats of PEG and AK2 peptides. The secondary structure of EMHPs is sensitive to the specific sequence of the peptidic building blocks, with CBD-containing EMHPs exhibiting a significant enhancement in the α-helical content as compared with the peptide alone. Elastomeric hydrogels formed by covalent cross-linking of the EMHPs had a compressive modulus of 1.06 ± 0.1 MPa. Neonatal human dermal fibroblasts (NHDFs) were able to adhere to the hydrogels within 1 h and to spread and develop F-actin filaments 24 h postseeding. NHDF proliferation was only observed on hydrogels containing RGDSP domains, demonstrating the importance of integrin engagement for cell growth and the potential use of these EMHPs as tissue engineering scaffolds. These cell-instructive, hybrid polymers are promising candidates as elastomeric scaffolds for tissue engineering.     

Increased bioethanol production from commercial tobacco cultivars overexpressing thioredoxin f grown under field conditions

Bioethanol is mainly produced from food crops such as sugar cane and maize, and this has been held partly responsible for the rise of food commodity prices. Tobacco, integrated in biorefinery facilities for the extraction of different compounds, could become an alternative feedstock for biofuel production. When grown for energy production, using high plant densities and several mowings during the growing season, tobacco can produce large amounts of inexpensive green biomass. We have bred two commercial tobacco cultivars (Virginia Gold and Havana 503B) to increase the carbohydrate content by the overexpression of thioredoxin f in the chloroplast. Marker-free transplastomic plants were recovered and their agronomic performance under field conditions was evaluated. These plants were phenotypically equivalent to their wild types yet showed increased starch (up to 280 %) and soluble sugar (up to 74 %) contents in leaves relative to their control plants. Fermentable sugars released from the stalk were also higher (up to 24 %) for transplastomic plants. After heat pretreatment, enzymatic hydrolysis and yeast fermentation of leaf and stalk hydrolysates, an average of 20–40 % more ethanol was obtained from transplastomic plants than their wild-type controls. We propose an integral exploitation of the entire tobacco plant managed as a forage crop (harvesting sugar and starch-rich leaves and lignocellulosic stalks) that could considerably cheapen the entire production process.     

Circadian clocks in changing weather and seasons: Lessons from the picoalga Ostreococcus tauri

Daylight is the primary cue used by circadian clocks to entrain to the day/night cycle so as to synchronize physiological processes with periodic environmental changes induced by Earth rotation. However, the temporal daylight pattern is not the same every day due to erratic weather fluctuations or regular seasonal changes. Then, how do circadian clocks operate properly in varying weather and seasons? In this paper, we discuss the strategy unveiled by recent studies of the circadian clock of Ostreococcus tauri, the smallest free‐living eukaryotic organism. It combines mechanisms controlling light inputs and clock sensitivity, shaping both the dynamics of the core circadian oscillator and its forcing by light so as to ensure stable and precise synchronization in all weather and seasons. Editor's suggested further reading in BioEssays: Another place, another timer: Marine species and the rhythms of life Abstract     

Regioselective and sequential reactivity of activated 2,5‐diketopiperazines

The electrophilic reactivity of Boc‐DKPs has been studied. Thanks to Boc activation, the opening ability of carbonyl lactam groups is enhanced. According to experimental conditions, this enabled the synthesis of Boc‐amino acid derivatives or original dipeptides via a regioselective and sequential way. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.