Biomedical subjects

Eric Assenat

Publications and source records attributed to Eric Assenat.

5 recordsLinked to original sources

PubMed2006

Is nuclear factor kappa-B the missing link between inflammation, cancer and alteration in hepatic drug metabolism in patients with cancer?

In the last few years, several studies have provided a causal link between constitutive activation of nuclear factor kappa-B (NF-kappaB) and the initiation and development of cancer. More recently, it appears that a cancer-induced inflammatory response may be an important factor in the inter-individual variability of the response to and toxic effects of cancer chemotherapy, as well as in the alteration of drug metabolism enzyme expression in patients. The relationships between chronic inflammation (or infection), cancer and drug metabolism are many: chronic infections lead to inflammation, inflammation may lead to cancer, cancer usually leads to an inflammatory syndrome, and inflammation alters the expression of drug metabolising enzymes and thus of the efficiency of cancer chemotherapy. This review focuses on the functional consequences of NF-kappaB activation during oncogenesis and on the expression of the major cytochrome P450s (CYP) involved in anticancer therapies. Finally, the potential role of NF-kappaB as the missing link between inflammation, cancer and alteration in hepatic drug metabolism in patients with cancer is discussed.

Cytochrome P-450 Enzyme System↗

PubMed2006

Initial endoscopic description of esophageal squamous cell carcinomas.

INTRODUCTION: The aim of this study was to evaluate initial endoscopic practices at diagnosis of esophageal squamous cell carcinoma in comparison with current recommendations. We wanted to develop a standard model for the endoscopy report which could be used in routine practice. PATIENTS AND METHODS: From January 2000 to December 2002, 122 patients were hospitalized for esophageal squamous cell carcinoma. The initial endoscopic reports were reviewed retrospectively and compared with a model report established on the basis of current recommendations. RESULTS: One hundred and nineteen reports were re-examined. The principal reason for performing the endoscopic examination was dysphagia in 73.9% of patients. Tumor measurements (height, upper and lower extremities) were recorded in 51.2%, 79% and 41% of reports, respectively. 14.4% of the analyzed reports concerned endoscopic procedures which were performed after a first endoscopic examination because the initial report provided an imprecise tumor description. Tissue samples taken during the initial endoscopy allowed a pathological diagnosis in 94.2% of patients. Lugol staining was performed in 2.5% of procedures. CONCLUSION: Insufficiently rigorous reporting compromises the reliability of initial upper digestive endoscopic procedures. Application of a standardized model for routine practice would favor more complete reports, starting with the first procedure.

Carcinoma, Squamous Cell↗

PubMed2006

[Irinotecan for the treatment of metastatic colorectal cancer].

In a dozen years of development, irinotecan (CPT11) became one of major therapeutics in the taking care of the metastatic colorectal cancer (CCRM). First used in monotherapy every three weeks, irinotecan has been later developed in association with 5FU and folinic acid according to two modalities of administration (bolus schedule administred weekly or infused schedule every two weeks). This association is now validated both in first and second line. Infused schedule (Folfiri) seems to introduce the best ratio of efficacy/tolerance. The association with the anti VEGF antibody (Avastin), bevacizumab) is promising. Moreover the association of the irinotecan with the anti EGFR antibody (Erbitux)), cetixumab) has show a efficacy in third line after progression under an protocol with irinotecan. Combinations with oxaliplatine (Irox, Irinox) or (Folfoxiri, Folfirinox) still remain in the course of appreciation notably in neoadjuvant context. An increment of dose seems accomplishable in monotherapy or in combination with/AF (high Folfiri doses) with a notable increment of responses rates. Nevertheless this strategy must again show a true clinical interest. Finally they are at promising developments in the fields of the irinotecan pharmacogenetic and pharmacogenomic.

Antimetabolites, Antineoplastic↗

PubMed2004

Interleukin 1beta inhibits CAR-induced expression of hepatic genes involved in drug and bilirubin clearance.

During the inflammatory response, intrahepatic cholestasis and decreased drug metabolism are frequently observed. At the hepatic level, the orphan nuclear constitutive androstane receptor (CAR) (NR1I3) controls phase I (cytochrome P450 [CYP] 2B and CYP3A), phase II (UGT1A1), and transporter (SLC21A6, MRP2) genes involved in drug metabolism and bilirubin clearance in response to xenobiotics such as phenobarbital or endobiotics such as bilirubin. We investigated the negative regulation of CAR, a glucocorticoid-responsive gene, via proinflammatory cytokine interleukin 1beta (IL-1beta) and lipopolysaccharides (LPSs) in human hepatocytes. We show that IL-1beta decreases CAR expression and decreases phenobarbital- or bilirubin-mediated induction of CYP2B6, CYP2C9, CYP3A4, UGT1A1, GSTA1, GSTA2, and SLC21A6 messenger RNA. This occurs via nuclear factor kappaB (NF-kappaB) p65 activation, which interferes with the enhancer function of the distal glucocorticoid response element that we have identified recently in the CAR promoter. We demonstrate that: (1) LPSs, IL-1beta, or overexpression of p65RelA inhibit glucocorticoid receptor (GR)-mediated CAR transactivation; (2) these suppressive effects can be blocked both by pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB activation, or by overexpression of SRIkBalpha, a NF-kappaB repressor; and (3) the GR agonist dexamethasone induces histone H4 acetylation at the proximal CAR promoter region, whereas LPSs and IL-1beta inhibit this acetylation as assessed via chromatin immunoprecipitation assay. In conclusion, GR/NF-kappaB interaction affects CAR gene transcription through chromatin remodeling and provide a mechanistic explanation for the long-standing observation that inflammation and sepsis inhibit drug metabolism while inducing intrahepatic cholestasis or hyperbilirubinemia.

Acetylation↗

PubMed2003

Pathophysiological factors affecting CAR gene expression.

The body defends itself against potentially harmful compounds, such as drugs and toxic endogenous compounds and their metabolites, by inducing the expression of enzymes and transporters involved in their metabolism and elimination. The orphan nuclear receptor CAR (NR1I3 controls phase I (CYP2B, CYP2C, CYP3A), phase II (UGT1A1), and transporter (SLC21A6, MRP2) genes involved in drug metabolism and bilirubin clearance. Constitutive androstane receptor (CAR) is activated by xenobiotics, such as phenobarbital, but also by toxic endogenous compounds such as bilirubin metabolite(s). To better understand the inter- and intravariability in drug detoxification, we studied the molecular mechanisms involved in CAR gene expression in human hepatocytes. We clearly identified CAR as a glucocorticoid receptor (GR) target gene, and we proposed the hypothesis of a signal transduction where the activation of GR plays a critical function in CAR-mediated cellular response. According to our model, chemicals or pathophysiological factors that affect GR function should decrease CAR function. To test this hypothesis, we recently investigated the effect of microtubule disrupting agents (MIAs) or proinflammatory cytokines. These compounds are well-known inhibitors of GR transactivation property. MIAs activate c-Jun N-terminal kinase (JNK), which phosphorylates and inactivates GR, whereas proinflammatory cytokines, such as IL-6 or IL1beta, induce AP-1 or NF-kB activation, respectively, leading to GR inhibition. As expected, we observed that these molecules inhibit both CAR gene expression and phenobarbital-mediated CYP gene expression in human hepatocytes.

Animals↗