Exposure of Caenorhabditis elegans to Dietary Nε-Carboxymethyllysine Emphasizes Endocytosis as a New Route for Intestinal Absorption of Advanced Glycation End Products.

The impact of dietary advanced glycation end products (dAGEs) on human health has been discussed in many studies but, to date, no consensual pathophysiological process has been demonstrated. The intestinal absorption pathways which have so far been described for dAGEs, the passive diffusion of free AGE adducts and transport of glycated di-tripeptides by the peptide transporter 1 (PEPT-1), are not compatible with certain pathophysiological processes described. To get new insight into the intestinal absorption pathways and the pathophysiological mechanisms of dAGEs, we initiated an in vivo study with a so-called simple animal model with a complete digestive tract, Caenorhabditis elegans. Dietary bacteria were chemically modified with glyoxylic acid to mainly produce Nε-carboxymethyllysine (CML) and used to feed the worms. We performed different immunotechniques using an anti-CML antibody for the relative quantification of ingested CML and localization of this AGE in the worms' intestine. The relative expression of genes encoding different biological processes such as response to stresses and intestinal digestion were determined. The physiological development of the worms was verified. All the results were compared with those obtained with the control bacteria. The results revealed a new route for the intestinal absorption of dietary CML (dCML), endocytosis, which could be mediated by scavenger receptors. The exposure of worms to dCML induced a reproductive defect and a transcriptional response reflecting oxidative, carbonyl and protein folding stresses. These data, in particular the demonstration of endocytosis of dCML by enterocytes, open up new perspectives to better characterize the pathophysiological mechanisms of dAGEs.

The receptor for advanced glycation end products is a sensor for cell-free heme.

Heme's interaction with Toll-like receptor 4 (TLR4) does not fully explain the proinflammatory properties of this hemoglobin-derived molecule during intravascular hemolysis. The receptor for advanced glycation end products (RAGE) shares many features with TLR4 such as common ligands and proinflammatory, prothrombotic, and pro-oxidative signaling pathways, prompting us to study its involvement as a heme sensor. Stable RAGE-heme complexes with micromolar affinity were detected as heme-mediated RAGE oligomerization. The heme-binding site was located in the V domain of RAGE. This interaction was Fe3+ -dependent and competitive with carboxymethyllysine, another RAGE ligand. We confirmed a strong basal gene expression of RAGE in mouse lungs. After intraperitoneal heme injection, pulmonary TNF-α, IL1ß, and tissue factor gene expression levels increased in WT mice but were significantly lower in their RAGE-/- littermates. This may be related to the lower activation of ERK1/2 and Akt observed in the lungs of heme-treated, RAGE-/- mice. Overall, heme binds to RAGE with micromolar affinity and could promote proinflammatory and prothrombotic signaling in vivo, suggesting that this interaction could be implicated in heme-overload conditions.

Heterocyclic Diamidine DNA Ligands as HOXA9 Transcription Factor Inhibitors: Design, Molecular Evaluation, and Cellular Consequences in a HOXA9-Dependant Leukemia Cell Model.

Most transcription factors were for a long time considered as undruggable targets because of the absence of binding pockets for direct targeting. HOXA9, implicated in acute myeloid leukemia, is one of them. To date, only indirect targeting of HOXA9 expression or multitarget HOX/PBX protein/protein interaction inhibitors has been developed. As an attractive alternative by inhibiting the DNA binding, we selected a series of heterocyclic diamidines as efficient competitors for the HOXA9/DNA interaction through binding as minor groove DNA ligands on the HOXA9 cognate sequence. Selected DB818 and DB1055 compounds altered HOXA9-mediated transcription in luciferase assays, cell survival, and cell cycle, but increased cell death and granulocyte/monocyte differentiation, two main HOXA9 functions also highlighted using transcriptomic analysis of DB818-treated murine Hoxa9-transformed hematopoietic cells. Altogether, these data demonstrate for the first time the propensity of sequence-selective DNA ligands to inhibit HOXA9/DNA binding both in vitro and in a murine Hoxa9-dependent leukemic cell model.

New anticancer active and selective phenylene-bisbenzothiazoles: synthesis, antiproliferative evaluation and DNA binding.

Novel amidino-derivatives of phenylene-bisbenzothiazoles were synthesized and tested for their antiproliferative activity against several human cancer cell lines, as well as DNA-binding properties. The synthetic approach used for preparation of isomeric amidino substituted-phenylene-bis-benzothyazoles 3a-3f was achieved by condensation reaction of isophthaloyl dichloride 1a and terephthaloyl dichloride 1b or with phthalic acid 1c with 5-amidinium-2-aminobenzothiolate 2a and 5-(imidazolinium-2-yl)-2-aminobenzothiolate 2b in good yields. The targeted compounds were converted in the desired water soluble dihydrochloride salts by reaction of appropriate free base with concd HCl in ethanol or acetic acid. All tested compounds (3a-3f) showed antiproliferative effects on tumour cells in a concentration-dependant manner. The strongest activity and cytotoxicity was observed for diimidazolinyl substituted phenylene-bisbenzothiazole compound 3b. These effects were shown to be related to DNA-binding properties, topoisomerase I and II poisoning effects and apoptosis induction. The highest tested selectivity towards tumour cells was observed for the imidazolyl substituted phenylene-benzothiazole 3d that showed no cytotoxic effects on normal fibroblasts making it an excellent candidate for further chemical optimization and preclinical evaluation.