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.

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.

Genetic analysis of peroxisome proliferator-activated receptor gamma1 splice variants in human colorectal cell lines.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor family. In colon, this transcription factor is involved in differentiation of absorptive cells. PPARgamma participates also in colon carcinogenesis and cancer progression.

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.

The human semaphorin 6B gene is down regulated by PPARs.

The peroxisome proliferator-activated receptors (PPARs) are ligand-inducible transcription factors and belong to the nuclear hormone receptor superfamily. They form heterodimers with the retinoid X receptor and bind to specific peroxisome proliferator-response elements. The latter are direct repeat elements of two hexanucleotides with the consensus sequence TG(A/T)CCT separated by a single nucleotide spacer.

Induction of the expression of the peroxisome proliferator-activated receptor alpha (PPARalpha) by clofibrate in jerboa tissues.

Peroxisome proliferator-activated receptor alpha (PPARalpha) is a member of the nuclear hormone receptor superfamily that can be activated by natural fatty acids and various xenobiotics, including clofibrate. This transcription factor primarily regulates genes involved in lipid metabolism and homeostasis. We present the expression pattern of the PPARalpha subtype in the adult jerboa Jaculus orientalis, determined by RT-PCR and Western blotting using specific probes and a polyclonal antibody for PPARalpha, respectively.

Clofibric acid down-regulation of metallothionein IIA in HepG2 human hepatoma cells.

Among the different hypotheses advanced to explain the peroxisome proliferator (PP)-induced hepatocarcinogenicity in rodents, one is based on the development of an oxidative stress due to an imbalance in the production of reactive oxygen species that leads to DNA damages and lipid peroxidation. On the other hand, human cells appear to be nonresponsive to PPs. As metallothionein proteins play an important antioxidant role, the aim of the present study was to investigate the expression of metallothionein IA (MTIA) and IIA (MTIIA) in HepG2 human hepatoma cells exposed to clofibric acid.