Elaboration of a thermosensitive smart biomaterial: From synthesis to the ex vivo bioadhesion evaluation

Alginate and chitosan are polysaccharides that are widely used in the biomedical field, especially as wound dressings. Controlled bioadhesion is an advanced functionality that offers the potential to reduce injuries due to the stripping-off of the biomaterial. Herein, we report the efficient grafting of poly-N(isopropylacryamide) (PNIPAM), a thermosensitive polymer that exhibits a lower critical solution temperature (LCST) at 32 °C on the alginate/chitosan polyelectrolyte complex (PEC) surface. In vitro studies did not exhibit a cytotoxic effect, and cells adhered preferentially on the LCST on PNIPAM grafted surfaces, as reported in the literature. Ex vivo investigations revealed that the adhesive behavior of the biomaterials was not the same on the liver and pancreas. The effect of the temperature on the bioadhesion to organs was unexpected, as PNIPAM surfaces exhibited higher adhesion at low temperature. The PNIPAM was therefore able to confer PEC matrix thermosensitivity, but due to the application force, interactions between PNIPAM chains and their substrate could influence bioadhesion on tissues

Expression and Function of Kruppel Like-Factors (KLF) in Carcinogenesis

Krüppel-like factor (KLF) family members share a three C2H2 zinc finger DNA binding domain, and are involved in cell proliferation and differentiation control in normal as in pathological situations. Studies over the past several years support a significant role for this family of transcription factors in carcinogenesis. KLFs can both activate and repress genes that participate in cell-cycle regulation. Among them, many up-regulated genes are inhibitors of proliferation, whereas genes that promote cell proliferation are repressed. However, several studies do present KLFs as positive regulator of cell proliferation. KLFs can be deregulated in multiple cancers either by loss of heterozygosity (LOH), somatic mutation or transcriptional silencing by promoter hypermethylation. Accordingly, KLF expression was shown to mediate growth inhibition when ectopically expressed in multiple cancer-derived cell lines through the inhibition of a number of key oncogenic signaling pathways, and to revert the tumorogenic phenotype in vivo. Taken together, these observations suggest that KLFs act as tumor suppressor. However, in some occasion, KLFs could act as tumor promoters, depending on “cellular context”. Thus, this review will discuss the roles and the functions of KLF family members in carcinogenesis, with a special focus on cancers from epithelial origin

Genetic and Epigenetic Alterations in Pancreatic Carcinogenesis

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide. Despite significant progresses in the last decades, the origin of this cancer remains unclear and no efficient therapy exists. PDAC does not arise de novo: three remarkable different types of pancreatic lesions can evolve towards pancreatic cancer. These precursor lesions include: Pancreatic intraepithelial neoplasia (PanIN) that are microscopic lesions of the pancreas, Intraductal Papillary Mucinous Neoplasms (IPMN) and Mucinous Cystic Neoplasms (MCN) that are both macroscopic lesions. However, the cellular origin of these lesions is still a matter of debate

Influence of Homogenization Technique and Blend Ratio on Chitosan/Alginate Polyelectrolyte Complex Properties

Polyelectrolyte complex (PEC) films were prepared from chitosan (CHI) and alginate (ALG) which are polymers of opposite charge. Two homogenization techniques and two ratios of ALG–CHI blends were compared: mechanical agitation under vacuum (ALG–CHI ST) or agitation by high turbulence (ALG–CHI UT) and 50/50 or 63/37 ratios. Surface and structure of PEC films are affected by the homogenization technique while the swelling percentage is only affected by polymer ratio. The homogenization ratio does not seem to influence in vitro cell proliferation. Results show that the UT homogenization technique with a 63/37 ratio, which gives films with a smooth, homogeneous surface and a higher rate of enzymatic resistance, is more efficient for cell proliferation and viability. These first results confirm the potential use of ALG–CHI films for surgery application

A method for purification, identification and validation of DNMT1 mRNA binding proteins

DNA methyltransferase 1 (DNMT1) is the enzyme responsible for the maintenance of DNA methylation patterns during cell division. DNMT1 expression is tightly regulated within the cell cycle. Our previous study showed that the binding of a protein with an apparent size of ~40 kDa on DNMT1 3’-UTR triggered the destabilization of DNMT1 mRNA transcript during Go/G1 phase. Using RNA affinity capture with the 3’-UTR of DNMT1 mRNA and matrix-assisted laser desorption-time of flight tandem mass spectrometry (MALDI-TOF-MS-MS) analysis, we isolated and identified AUF 1 (AU-rich element ARE:poly-(U)-binding/degradation factor) as the binding protein. We then validated the role of this protein in the destabilization of DNMT1 mRNA. In this report, we detail the different approaches used for the isolation, the identification of a RNA binding protein and the validation of its role

Méthylation de l'ADN et expression des microARNs dans la carcinogénèse pancréatique

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

[New molecular targets in pancreatic cancer]

International audienceThe understanding of the biology of pancreatic carcinoma has greatly benefited from studies of genetic alterations and molecular expression in experimental models as well as in pre-cancerous and cancerous tissues by mean of molecular amplification and large scale transcriptome analysis. P16, TP53, DPC4/Smad4 tumor suppressor pathways are genetically inactivated in the majority of pancreatic carcinomas, whereas oncogenic k-ras is activated. The activating mutation of the K-ras oncogene on codon 12 seems to occur early in pancreatic carcinogenesis and detecting its mutation in tumor samples could have a clinical relevance in term of positive (improvement of current histological diagnosis) and differential diagnosis (versus chronic pancreatitis) of pancreatic cancer. At a late stage of tumor development, an increase of telomerase activity, an over expression of growth factors and/or their receptors (EGF, nerve growth factor, gastrin, bombesin), of proangiogenic factors (VEGF, FGF, PDGF), of invasiveness factors (metalloproteinases, E-cadherin, beta integrin, urokinase and tissue plasminogen activator) occur. All these molecular events contribute to the progression and to the metastatic potential of this carcinoma. New markers and targets are currently studied among microRNA and epigenetics events such as methylation and acetylation. Among all these molecular markers, some are now tested for their potential clinical interest in term of diagnosis or therapeutic target

DNA Methylation and Cancer Diagnosis

DNA methylation is a major epigenetic modification that is strongly involved in the physiological control of genome expression. DNA methylation patterns are largely modified in cancer cells and can therefore be used to distinguish cancer cells from normal tissues. This review describes the main technologies available for the detection and the discovery of aberrantly methylated DNA patterns. It also presents the different sources of biological samples suitable for DNA methylation studies. We discuss the interest and perspectives on the use of DNA methylation measurements for cancer diagnosis through examples of methylated genes commonly documented in the literature. The discussion leads to our consideration for why DNA methylation is not commonly used in clinical practice through an examination of the main requirements that constitute a reliable biomarker. Finally, we describe the main DNA methylation inhibitors currently used in clinical trials and those that exhibit promising results

E3 Ubiquitin Ligase TRIP12: Regulation, Structure, and Physiopathological Functions

The Thyroid hormone Receptor Interacting Protein 12 (TRIP12) protein belongs to the 28-member Homologous to the E6-AP C-Terminus (HECT) E3 ubiquitin ligase family. First described as an interactor of the thyroid hormone receptor, TRIP12’s biological importance was revealed by the embryonic lethality of a murine model bearing an inactivating mutation in the TRIP12 gene. Further studies showed the participation of TRIP12 in the regulation of major biological processes such as cell cycle progression, DNA damage repair, chromatin remodeling, and cell differentiation by an ubiquitination-mediated degradation of key protein substrates. Moreover, alterations of TRIP12 expression have been reported in cancers that can serve as predictive markers of therapeutic response. The TRIP12 gene is also referenced as a causative gene associated to intellectual disorders such as Clark–Baraitser syndrome and is clearly implicated in Autism Spectrum Disorder. The aim of the review is to provide an exhaustive and integrated overview of the different aspects of TRIP12 ranging from its regulation, molecular functions and physio-pathological implications