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(1) Background: Immunosuppression is a key barrier to effective anti-cancer therapies, particularly in triple-negative breast cancer (TNBC), an aggressive and difficult to treat form of breast cancer. We investigated here whether the combination of doxorubicin, a standard chemotherapy in TNBC with glyceryltrinitrate (GTN), a nitric oxide (NO) donor, could overcome chemotherapy resistance and highlight the mechanisms involved in a mouse model of TNBC. (2) Methods: Balb/C-bearing subcutaneous 4T1 (TNBC) tumors were treated with doxorubicin (8 mg/Kg) and GTN (5 mg/kg) and monitored for tumor growth and tumor-infiltrating immune cells. The effect of treatments on MDSCs reprogramming was investigated ex vivo and in vitro. (3) Results: GTN improved the anti-tumor efficacy of doxorubicin in TNBC tumors. This combination increases the intra-tumor recruitment and activation of CD8+ lymphocytes and dampens the immunosuppressive function of PMN-MDSCs PD-L1low. Mechanistically, in PMN-MDSC, the doxorubicin/GTN combination reduced STAT5 phosphorylation, while GTN +/− doxorubicin induced a ROS-dependent cleavage of STAT5 associated with a decrease in FATP2. (4) Conclusion: We have identified a new combination enhancing the immune-mediated anticancer therapy in a TNBC mouse model through the reprograming of PMN-MDSCs towards a less immunosuppressive phenotype. These findings prompt the testing of GTN combined with chemotherapies as an adjuvant in TNBC patients experiencing treatment failure.

International audience; A phosphine gold(I) and phosphine-phosphonium gold(I) complexes bearing a fluorescent coumarin moiety were synthesized and characterized. Both complexes displayed interesting photophysical properties: good molar absorption coefficient, good quantum yield of fluorescence, and ability to be tracked in vitro thanks to two-photon imaging. Their in vitro and in vivo biological properties were evaluated onto cancer cell lines both human and murine and into CT26 tumor-bearing BALB/c mice. They displayed moderate to strong antiproliferative properties and the phosphine-phosphonium gold(I) complex induced significant in vivo anti-cancer effect.

International audience; Boron neutron capture therapy (BNCT) has the potential to specifically destroy tumor cells without damaging the tissues infiltrated by the tumor. BNCT is a binary treatment method based on the combination of two agents that have no effect when applied individually: 10B and thermal neutrons. Exclusively, the combination of both produces an effect, whose extent depends on the amount of 10B in the tumor but also on the organs at risk. It is not yet possible to determine the 10B concentration in a specific tissue using non-invasive methods. At present, it is only possible to measure the 10B concentration in blood and to estimate the boron concentration in tissues based on the assumption that there is a fixed uptake of 10B from the blood into tissues. On this imprecise assumption, BNCT can hardly be developed further. A therapeutic approach, combining the boron carrier for therapeutic purposes with an imaging tool, might allow us to determine the 10B concentration in a specific tissue using a non-invasive method. This review provides an overview of the current clinical protocols and preclinical experiments and results on how innovative drug development for boron delivery systems can also incorporate concurrent imaging. The last section focuses on the importance of proteomics for further optimization of BNCT, a highly precise and personalized therapeutic approach.

Deregulation of the dynamic crosstalk between the gut microbiota, intestinal epithelial cells, and immune cells is critically involved in the development of inflammatory bowel disease and the overgrowth of opportunistic pathogens, including the human opportunistic fungus Candida albicans. In the present study, we assessed the effect of N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a protein kinase A inhibitor, on the migration of macrophages to C. albicans through dextran sulphate sodium (DSS)-challenged Caco-2 cells. We also investigated the impact of H89 on intestinal inflammation and C. albicans clearance from the gut, and determined the diversity of the gut microbiota in a murine model of DSS-induced colitis. H89 reduced the migration of macrophages to C. albicans through DSS-challenged Caco-2 cells. In addition, H89 decreased C. albicans viability and diminished the expression of pro-inflammatory cytokines and innate immune receptors in macrophages and colonic epithelial Caco-2 cells. In mice with DSS-induced colitis, H89 attenuated the clinical and histological scores of inflammation and promoted the elimination of C. albicans from the gut. H89 administration to mice decreased the overgrowth of Escherichia coli and Enterococcus faecalis populations while Lactobacillus johnsonii populations increased significantly. Overall, H89 reduced intestinal inflammation and promoted the elimination of C. albicans from the gut.

International audience; Two new gold(I)–BODIPY–imidazole based trackable therapeutic bimetallic complexes have been synthesized and fully characterized. They display strong antiproliferative properties on several types of cancers including colon, breast, and prostate and one of them presents a significant anti-inflammatory effect. Additionally, the two compounds could be visualised in vitro by confocal microscopy in the submicromolar range.

IF 1.436; International audience; In this study we evaluated the effects of low dose of bleomycin in an associative treatment strategy in solid tumor cells. For this purpose, Human and murine colon cancer (SW480, HCT8, and CT26), and murine melanoma (B16-F10) cells were treated with different agents including protein kinase C, and c-jun NH2-terminal kinase inhibitors, and tumor necrosis factor-related apoptosis-inducing ligand. Apoptosis was identified by morphological criteria. Reactive oxygen species are evaluated by flow cytometry. Our data showed that bleomycin (100 µM) induced apoptosis in all the four cell lines tested with a level ranging from 30 to 60%. However, at lower dose (25 µM), bleomycin was less efficient to trigger apoptosis. In contrast, when bleomycin (25 µM) was combined with the protein kinase C inhibitor chelerythrine, or tumor necrosis factor-related apoptosis-inducing ligand, it elicited more apoptotic cell death ranging from 40 to 75%, depending on the cell type, whereas when it was associated with the c-jun NH2-terminal kinase inhibitor SP600125, bleomycin displayed different cell death responses. If bleomycin and SP600125 enhanced apoptosis in two colon cancer cells, HCT-8, and CT26, they reduced to 50% apoptosis in the melanoma B16-F10 cells, and were not synergistic in the human colon cancer cells, SW480. This synergism seemed to rely partially to reactive oxygen species, because N-acetyl cysteine inhibited apoptosis in some cells and with some agents. These findings indicate that tumor necrosis factor-related apoptosis-inducing ligand, and protein kinase C inhibition can represent candidates for improved cancer chemotherapy.

International audience; S-nitrosylation is the covalent attachment of nitric oxide radical to the thiol side chain of cysteine. The death receptor Fas/CD95 can be S-nitrosylated in cancer cell lines by NO donors or iNOS activation. This posttranslational modification (PTM) induces Fas aggregation into lipid rafts and enhances FasL-mediated signaling and apoptosis. In this report, we describe the detection of Fas S-nitrosylation by the most commonly used method, the biotin switch assay (BSA) technique, that allows the detection of this very labile covalent modification in cells or tissues. Briefly, this technique relies on the ability of ascorbate to reduce the covalent bond between the NO radical and the protein, allowing the exchange of the NO radical with a thiol reactive biotin-HPDP. The biotinylated proteins are then easily purified by using NeutrAvidin resin, separated by SDS-PAGE resolution and analyzed by Western blotting.

International audience; Various studies in western countries found Akt amplification to be a frequent event in human cancers, including bladder, but the correlation with clinicopathological features is controversial. Such studies have not been reported in African populations, including Tunisians. The purpose of this study was to assess expression of the phosphorylated/activated forms of Akt in tumors from Tunisian patients with bladder cancer and to correlate its expression with pathological and clinical parameters of the disease. The study included 72 patients of whom 34 were diagnosed as low- to medium-grade and 35 as high-grade; 30 were muscle stage and 39 non-muscle stage. Primary tumors from these patients, normal adjacent tissues, or bladder cancer cell-lines were analyzed for Ser473 phosphorylated Akt expression by Western blot. Seventy-two percent of primary tumors from patients with bladder cancer had increased levels of p-Akt. The p-Akt levels in patients with high-grade bladder cancer were significantly elevated compared to patients with low- or medium-grade bladder cancer. In invasive carcinoma, the p-Akt level was significantly higher than in superficial non-invasive bladder tumors. Concerning the influence of tobacco on Akt activation, no significant differences of p-Akt expression were found between non-smoker and smoker patients. Altogether, our results suggest that Akt activation can provide useful prognostic information and that tobacco represents a serious risk factor for recurrence in a cohort of Tunisian patients.

International audience; Ten metal-based complexes and associated ligands have been synthesized and characterized. One of the metal ligands is a coumarin-phosphine derivative, which displays tunable fluorescence properties. The fluorescence is quenched in the case of the free ligand and ruthenium and osmium complexes, whereas it is strong for the gold complexes and phosphonium derivatives. These trends were rationalized by theoretical calculations, which revealed non-radiative channels involving a dark state for the free ligands that is lower in energy than the emissive state and is responsible for the quenching of fluorescence. For the Ru-II and Os-II complexes, other non-radiative channels involving the manifold of singlet and triplet excited states may play a role. The anti-proliferative properties of all the compounds were evaluated in cancer cell lines (SW480, HCT116, MDA-MB-231 and MCF-7); higher IC50 values were obtained for gold(I) complexes, with the free ligands being only weakly cytotoxic.

International audience; BACKGROUND & AIMS: Fas belongs to the family of tumor necrosis factor receptors which induce apoptosis. Many cancer cells express Fas but do not undergo Fas-mediated apoptosis. Nitric oxide reverses this resistance by increasing levels of Fas at the plasma membrane. We studied the mechanisms by which NO affects Fas function. METHODS: Colon and mammary cancer cell lines were incubated with the NO donor glyceryl trinitrate or lipid A; S-nitrosylation of Fas was monitored using the biotin switch assay. Fas constructs that contained mutations at cysteine residues that prevent S-nitrosylation were used to investigate the involvement of S-nitrosylation in Fas-mediated cell death. Apoptosis was monitored according to morphologic criteria. RESULTS: NO induced S-nitrosylation of cysteine residues 199 and 304 in the cytoplasmic part of Fas. In cancer cells that overexpressed wild-type Fas, S-nitrosylation induced Fas recruitment to lipid rafts and sensitized the cells to Fas ligand. In cells that expressed a mutant form of Fas in which cysteine 304 was replaced by valine residue, NO-mediated translocation of Fas to lipid rafts was affected and the death-inducing signal complex and synergistic effect of glyceryl trinitrate-Fas ligand were inhibited significantly. These effects were not observed in cells that expressed Fas with a mutation at cysteine 199. CONCLUSIONS: We identified post-translational modifications (S-nitrosylation of cysteine residues 199 and 304) in the cytoplasmic domain of Fas. S-nitrosylation at cysteine 304 promotes redistribution of Fas to lipid rafts, formation of the death-inducing signal complex, and induction of cell death.

Background & Aims: We have previously reported the role of nitric oxide in colon tumor regression in vivo. The present study was designed to explore the influence of an endogenous nitric oxide donor, glyceryl trinitrate (GTN), on cell death pathways in colon cancer cells. Methods: Human colon cancer cell lines were treated with the NO donor GTN. Apoptosis was identified by morphological criteria and the terminal deoxynucleotidyl transferase–mediated deoxyuridine (TUNEL) method. The mitochondrial transmembrane potential was studied by flow cytometry, cytochrome c release by Western blot, and caspase activation by combining fluorogenic peptide substrates, peptide inhibitors, and immunoblotting. Expression of death receptors was studied by flow cytometry and confocal microscopy. Results: GTN induces a dose- and time-dependent cell death by apoptosis in colon cancer cells. This cell death pathway involves the mitochondria and caspases, mainly caspase-1 and caspase-10. In contrast, caspase-3 activation is a late and limited event. Death receptors are not involved in GTN-mediated cell death, while GTN sensitizes tumor cells to Fas-ligand–induced apoptosis. This permissive effect correlates with an increased expression of Fas receptor and a decreased expression of several endogenous inhibitors of apoptosis (IAPs). Conclusions: Our results indicate that GTN (1) activates an unusual caspase cascade to induce apoptosis in colon cancer cells and (2) sensitizes these cells to Fas-mediated cell death by increasing the expression of Fas and decreasing the expression of several IAPs. GASTROENTEROLOGY 2002;123:235-246

Anthracyclines such as daunorubicin (DNR) generate radical oxygen species (ROS), which account, at least in part, for their cytotoxic effect. We observed that early ceramide generation (within 6-10 min) through neutral sphingomyelinase stimulation was inhibitable by the antioxidants N-acetylcysteine and pyrrolidine dithiocarbamate, which led to a decrease in apoptosis (>95% decrease in DNA fragmentation after 6 h). Furthermore, we observed that DNR triggers the c-Jun N-terminal kinase (JNK) and the transcription factor activated protein-1 through an antioxidant-inhibitable mechanism. Treatment of U937 cells with cell-permeant ceramides induced both an increase in ROS generation and JNK activation, and apoptosis, all of which were antioxidant-sensitive. In conclusion, DNR-triggered apoptosis implicates a ceramide-mediated, ROS-dependent JNK and activated protein-1 activation.

Several studies have suggested that diacylglycerol can affect the induction of apoptosis induced by toxicants and ceramide. The present study demonstrates that clinically relevant concentrations of the chemotherapeutic drugs daunorubicin and mitoxantrone (0.2-1 microM) transiently stimulated concurrently with sphingomyelin-derived ceramide generation and diacylglycerol and phosphorylcholine production within 4 to 10 min via phospholipase C hydrolysis of phosphatidylcholine. Pretreatment of cells with the xanthogenate compound D609, a potent inhibitor of phosphatidylcholine-phospholipase C, led to significant inhibition of drug triggered diacylglycerol and phosphorylcholine production and to a sustained increase in ceramide levels for a period up to 2 h. Moreover, D609 pretreatment induced both cell death and ceramide generation at daunorubicin and mitoxantrone concentrations previously shown to be ineffective (i.e., 0.1 microM). These results underline the importance of diacylglycerol in the regulation of programmed cell death and strongly argue for a balance between apoptotic (ceramide) and survival (diacylglycerol) signal transducers.

Daunorubicin induces apoptosis in myeloid leukemia cells by activation of neutral sphingomyelinase and ceramide generation occurring 4–10 min after daunorubicin addition. We show here that daunorubicin is able to increase the phosphoinositide 3-kinase activity and enhance intracellular phosphoinositide 3-kinase lipid products prior to ceramide generation. Daunorubicin activates Akt, a downstream phosphoinositide 3-kinase effector. Interestingly, the phosphoinositide 3-kinase inhibitors wortmannin and LY294002 accelerate daunorubicin-induced apoptosis in U937 cells. The phosphoinositide 3-kinase/Akt pathway has been involved in cell survival following serum deprivation, tumor necrosis factor α, anti-Fas and UV radiations. Our results suggest that anti-tumor agents such as daunorubicin may also activate anti-apoptotic signals that could contribute to drug resistance.

One of the key features of tumor cells is the acquisition of resistance to apoptosis. Thus, novel therapeutic strategies that circumvent apoptotic resistance and result in tumor elimination are needed. One strategy to induce apoptosis is to activate death receptor signaling pathways. In the tumor microenvironment, stimulation of Fas, Death receptor 4 (DR4) and tumor necrosis factor receptor 1 (TNFR1) can initiate multiple signaling pathways driving either tumor promotion or elimination. Nitric oxide (NO) is an important signaling molecule now understood to play a dual role in cancer biology. More and more attention is directed toward the role displayed by S-nitrosylation, the incorporation of an NO moiety to a cysteine thiol group, in promoting cell death in tumor cells. Protein post-translation modification by S-nitrosylation has decisive roles in regulating signal-transduction pathways. In this review, we summarize several examples of protein modification by S-nitrosylation that regulate signaling pathways engaged by members of the TNF superfamily (Fas ligand (FasL), Tumor-necrosis-factor-related apoptosis inducing ligand (TRAIL) and TNFalpha (TNFα)) and the way it influences cell fate decisions., Graphical abstract fx1, Highlights • An overview of NO in regulating signaling pathways engaged by FasL, TRAIL and TNFα. • S-nitrosylation regulates protein activity and cancer cell death. • Exploiting NO for cancer therapy.