Newly identified tumor suppressor functions of ING proteins.

The INhibitor of Growth (ING) proteins (ING1, ING2, ING3, ING4 and ING5) are a family of epigenetic regulators. Their decreased expression in numerous cancers led to identifying the ING proteins as gatekeeper tumor suppressors as they regulate cell cycle progression, apoptosis and senescence. Subsequently, they were also described as caretaker tumor suppressors through their involvement in DNA replication and the DNA damage response (DDR).

Emerging Roles of DDB2 in Cancer.

Damage-specific DNA-binding protein 2 (DDB2) was originally identified as a DNA damage recognition factor that facilitates global genomic nucleotide excision repair (GG-NER) in human cells. DDB2 also contributes to other essential biological processes such as chromatin remodeling, gene transcription, cell cycle regulation, and protein decay. Recently, the potential of DDB2 in the development and progression of various cancers has been described.

DDB2 (damaged-DNA binding 2) protein: a new modulator of nanomechanical properties and cell adhesion of breast cancer cells.

DDB2, known for its role in DNA repair, was recently shown to reduce mammary tumor invasiveness by inducing the transcription of IκBα, an inhibitor of NF-κB activity. Since cellular adhesion is a key event during the epithelial to mesenchymal transition (EMT) leading to the invasive capacities of breast tumor cells, the aim of this study was to investigate the role of DDB2 in this process. Thus, using low and high DDB2-expressing MDA-MB231 and MCF7 cells, respectively, in which DDB2 expression was modulated experimentally, we showed that DDB2 overexpression was associated with a decrease of adhesion abilities on glass and plastic areas of breast cancer cells.

Interaction of Iron II Complexes with B-DNA. Insights from Molecular Modeling, Spectroscopy, and Cellular Biology.

We report the characterization of the interaction between B-DNA and three terpyridin iron II complexes. Relatively long time-scale molecular dynamics (MD) is used in order to characterize the stable interaction modes. By means of molecular modeling and UV-vis spectroscopy, we prove that they may lead to stable interactions with the DNA duplex.

Manganese superoxide dismutase in breast cancer: from molecular mechanisms of gene regulation to biological and clinical significance.

Breast cancer is one of the most common malignancies of all cancers in women worldwide. Many difficulties reside in the prediction of tumor metastatic progression because of the lack of sufficiently reliable predictive biological markers, and this is a permanent preoccupation for clinicians. Manganese superoxide dismutase (MnSOD) may represent a rational candidate as a predictive biomarker of breast tumor metastatic progression, because its gene expression is profoundly altered between early and advanced breast cancer, in contrast to expression in the normal mammary gland.

DDB2: a novel regulator of NF-κB and breast tumor invasion.

The DNA repair protein damaged DNA-binding 2 (DDB2) has been implicated in promoting cell-cycle progression by regulating gene expression. DDB2 is selectively overexpressed in breast tumor cells that are noninvasive, but not in those that are invasive. We found that its overexpression in invasive human breast tumor cells limited their motility and invasiveness in vitro and blocked their ability to colonize lungs in vivo, defining a new function for DDB2 in malignant progression.

Regulation of the high basal expression of the manganese superoxide dismutase gene in aggressive breast cancer cells.

A high basal expression of manganese superoxide dismutase (MnSOD) has been reported in aggressive breast cancer cells, according to an unknown mechanism, and contributes to their invasive abilities. Here, we report the involvement of Sp1 and nuclear factor-κB (NF-κB) transcription factors in this high basal expression of MnSOD in aggressive breast cancer cells. Suppression or inactivation of Sp1 showed that it plays an essential role in the high MnSOD expression in aggressive breast cancer cells through a unique binding site identified by chromatin immunoprecipitation (ChIP) assay and functional analysis of the MnSOD proximal promoter.

Photochemical internalization for pDNA transfection: evaluation of poly(d,l-lactide-co-glycolide) and poly(ethylenimine) nanoparticles.

The main objective of this study was to prepare two types of nanoparticles with poly(d,l-lactide-co-glycolide) (PLGA) and polyethylenimine (PEI) polymers. Plasmid DNA (pDNA) was adsorbed either on PLGA/PEI nanoparticles, or as PEI/DNA complex onto the surface of PLGA nanoparticles. Both types of nanoparticles were prepared by the double emulsion method.

Photodynamic therapy targeting neuropilin-1: Interest of pseudopeptides with improved stability properties.

The general strategy developed aims to favor the vascular effect of photodynamic therapy by targeting tumor vasculature. Since angiogenic endothelial cells represent an interesting target to potentiate this vascular effect, we previously described the conjugation of a photosensitizer to a peptide targeting neuropilins (NRPs) over-expressed specially in tumor angiogenic vessels and we recently characterized the mechanism of photosensitization-induced thrombogenic events. Nevertheless, in glioma-bearing nude mice, we demonstrated that the peptide moiety was degraded to various rates according to time after intravenous administration.

Optimization of a new non-viral vector for transfection: Eudragit nanoparticles for the delivery of a DNA plasmid.

The development of new vectors to deliver DNA into cells for therapy of cancers or genetic diseases has been a major area of research for many years. However, the clinical application of this technology requires the development of efficient, reliable and sterile vectors enabling the transfer of genes in vivo. Non viral, polymer or lipid-based vectors offer a new impetus to gene therapy because they are less toxic than viral vectors (no endogenous recombination, fewer immunological reactions, easy production and delivery of large-sized plasmid).

Peptide-conjugated chlorin-type photosensitizer binds neuropilin-1 in vitro and in vivo.

The strategy developed aims to favor the vascular effect of photodynamic therapy (PDT) by targeting tumor vasculature. This approach is considered by coupling a photosensitizer (PS) to an heptapeptide targeting neuropilin-1 (NRP-1). We previously demonstrated that this new conjugated PS, which binds to recombinant NRP-1 protein, was a much more potent PS compared to the non-conjugated PS in human umbilical vein endothelial cells (HUVEC) expressing NRP-1, due to the coupling of the peptide moiety.

Identification of DDB2 protein as a transcriptional regulator of constitutive SOD2 gene expression in human breast cancer cells.

Manganese superoxide dismutase plays a role in breast tumor cell growth, which depends on its constitutive expression. However, the mechanisms responsible for the regulation of constitutive SOD2 gene expression at different malignant phenotype in breast cancers remain to be determined. The present study reports the identification and characterization of a DNA sequence located in the proximal promoter of the SOD2 gene, which forms a complex with a nuclear protein from breast tumor MCF-7 cells.

PTEN expression controls cellular response to cetuximab by mediating PI3K/AKT and RAS/RAF/MAPK downstream signaling in KRAS wild-type, hormone refractory prostate cancer cells.

Overexpression of epidermal growth factor receptor (EGFR) and mutation of pten tumor suppressor gene in human cancer cells leads to activated EGFR downstream signaling including PI3-kinase/AKT (PI3K/AKT) and/or mitogen-activated protein kinases (RAS/RAF/MAPK) and have been linked to resistance to anti-EGFR targeted therapies. Cetuximab is a chimeric IgG1 monoclonal antibody that binds the EGFR with high specificity and have been developed as promising therapeutic anticancer treatments in several solid tumors, including colorectal and head and neck squamous cell carcinomas. Cetuximab activity is related to PI3K/AKT and RAS/RAF/MAPK signaling pathways functionality and its activity has been shown to be higher in wild-type KRAS tumors.

P53 and PTEN expression contribute to the inhibition of EGFR downstream signaling pathway by cetuximab.

Cetuximab (Erbitux) is an anti-epidermal growth factor receptor (EGFR) monoclonal antibody whose activity is related to the inhibition of EGFR downstream signaling pathways. P53 and phosphatase and tensin homologue deleted on chromosome 10 (PTEN) have been reported to control the functionality of PI3K/AKT signaling. In this study we evaluated whether reintroducing P53 using non-viral gene transfer enhances PTEN-mediated inhibition of PI3K/AKT signaling by cetuximab in PC3 prostate adenocarcinoma cell line bearing p53 and pten mutations.

Damaged DNA binding protein 2 plays a role in breast cancer cell growth.

The Damaged DNA binding protein 2 (DDB2), is involved in nucleotide excision repair as well as in other biological processes in normal cells, including transcription and cell cycle regulation. Loss of DDB2 function may be related to tumor susceptibility. However, hypothesis of this study was that DDB2 could play a role in breast cancer cell growth, resulting in its well known interaction with the proliferative marker E2F1 in breast neoplasia.

[PPARs and cell-cell or cell-extracellular matrix interactions].

The peroxisome proliferator-activated receptors (PPARs) are transcription factors and belong to the superfamily of nuclear receptors. They are encoded by three genes located on different chromosomes: PPARalpha, PPARbeta/delta and PPARgamma. PPARalpha plays a key role in the control of lipid metabolism and homeostasis.

Role of manganese superoxide dismutase on growth and invasive properties of human estrogen-independent breast cancer cells.

Manganese superoxide dismutase (MnSOD) is known to play a role in cancer. MnSOD exerts a tumor suppressive effect in estrogen-dependent human breast cancer cells. In the present study we investigated the in vitro role of MnSOD in the growth of some aggressive and highly metastatic estrogen-independent breast cancer cells, i.

Immunoselection and characterization of a human genomic PPAR binding fragment located within POTE genes.

Peroxisome proliferator-activated receptors (PPARs) are ligand-inducible transcription factors and belong to the nuclear hormone receptor superfamily. They form heterodimers with retinoid X receptor (RXR) and bind to specific PPAR-response elements. To identify novel PPAR target genes, we developed an affinity method to isolate human genomic fragments containing binding sites for PPARs.

Effects of PPAR and RXR ligands in semaphorin 6B gene expression of human MCF-7 breast cancer cells.

This study tests the hypothesis that the activators of peroxisome proliferator-activated receptors (PPARs) and 9-cis-retinoic acid receptor (RXR) regulate human semaphorin 6B (Sema6B) gene expression. The human MCF-7 breast adenocarcinoma cell line was chosen because it expresses Sema6B at a high level. The Sema6B mRNA level was analyzed by RT-PCR and the semaphorin 6B protein content was determined using a polyclonal antibody that we have produced and characterized.

Comparison of cytotoxicity induced by hypolipidemic drugs via reactive oxygen species in human and rodent liver cells.

Hypolipidemic drugs (HP drugs) are xenobiotics belonging to the peroxisome proliferator family which are used as pharmaceuticals in the treatment of human hyperlipidemia and hypercholesterolemia. They cause hepatocarcinogenesis in rodents by increasing cell proliferation. One hypothesis is that this hepatocarcinogenic effect is caused by induced oxidative stress resulting from the overproduction of reactive oxygen species (ROS) and from a decreasing antioxidant defense.

Stimulation of mitochondrial activity by p43 overexpression induces human dermal fibroblast transformation.

Mitochondrial dysfunctions are frequently reported in cancer cells, but their direct involvement in tumorigenesis remains unclear. To understand this relation, we stimulated mitochondrial activity by overexpression of the mitochondrial triiodothyronine receptor (p43) in human dermal fibroblasts. In all clones, this stimulation induced morphologic changes and cell fusion in myotube-like structures associated with the expression of several muscle-specific genes (Myf5, desmin, connectin, myosin, AchRalpha).

Effect of acute and chronic psychostimulant drugs on redox status, AP-1 activation and pro-enkephalin mRNA in the human astrocyte-like U373 MG cells.

In order to approach the astroglial implication of addictive and neurotoxic processes associated with psychostimulant drug abuse, the effects of amphetamine or cocaine (1-100 microM) on redox status, AP-1 transcription factor and pro-enkephalin, an AP-1 target gene, were investigated in the human astrocyte-like U373 MG cells. We demonstrated an early increase in the generation of radical oxygen species and in the formation of 4-hydroxynonenal-adducts reflecting the pro-oxidant action of both substances. After 1 h or 96 h of treatment, Fos and Jun protein levels were altered and the DNA-binding activity of AP-1 was increased in response to both substances.

Decrease of human hepatoma cell growth by arachidonic acid is associated with an accumulation of derived products from lipid peroxidation.

We showed that the metabolism of arachidonic acid (AA) in HepG2 cells generates reactive oxygen species (ROS), which activate the p38 mitogen-activated protein kinase (MAPK) pathway and the redox-sensitive transcription factors AP-1 and NF-kappaB, leading to the induction of the antioxidant manganese superoxide dismutase gene. The present study reports that AA decreases the HepG2 cell growth by 40% and 55% after a treatment for 24 and 48 h, respectively. This effect was blocked by an inhibitor of lipoxygenase/cytochrome P450 monooxygenase pathways and by the antioxidants.

Arachidonic acid activates a functional AP-1 and an inactive NF-kappaB complex in human HepG2 hepatoma cells.

Exogenous arachidonic acid (AA) has been shown to induce the antioxidant manganese superoxide dismutase gene by reactive oxygen species (ROS) derived from AA metabolism and the participation of the p38 mitogen-activated protein kinase (MAPK) pathway in human HepG2 hepatoma cells. The goal of this study was to investigate the effect of AA on the activation of the two redox-sensitive transcription factors AP-1 and NF-kappaB in HepG2 cells. Using electrophoretic mobility shift assays, DNA-binding activities of AP-1 and NF-kappaB were markedly increased in AA-treated HepG2 cells.