Synthesis and Biological Activity of 3-(Heteroaryl)quinolin-2(1H)-ones Bis-Heterocycles as Potential Inhibitors of the Protein Folding Machinery Hsp90.

In the context of our SAR study concerning 6BrCaQ analogues as C-terminal Hsp90 inhibitors, we designed and synthesized a novel series of 3-(heteroaryl)quinolin-2(1H), of types 3, 4, and 5, as a novel class of analogues. A Pd-catalyzed Liebeskind-Srogl cross-coupling was developed as a convenient approach for easy access to complex purine architectures. This series of analogues showed a promising biological effect against MDA-MB231 and PC-3 cancer cell lines. This study led to the identification of the best compounds, 3b (IC50 = 28 µM) and 4e, which induce a significant decrease of CDK-1 client protein and stabilize the levels of Hsp90 and Hsp70 without triggering the HSR response.

Synthesis and antiproliferative activity of 6BrCaQ-TPP conjugates for targeting the mitochondrial heat shock protein TRAP1.

A series of 6BrCaQ-Cn-TPP conjugates 3a-f and 5 was designed and synthesized as a novel class of TRAP1 inhibitors. Compound 3a displayed an excellent anti-proliferative activity with mean GI50 values at a nanomolar level in a diverse set of human cancer cells (GI50 = 0.008-0.30 µM) including MDA-MB231, HT-29, HCT-116, K562, and PC-3 cancer cell lines. Moreover, the best lead compound 6BrCaQ-C10-TPP induces a significant mitochondrial membrane disturbance combined to a regulation of HSP and partner protein levels as a first evidence that his mechanism of action involves the TRAP-1 mitochondrial Hsp90 machinery.

Assessment of various formulation approaches for the application of beta-lapachone in prostate cancer therapy.

Beta-lapachone (ß-Lap) is an anticancer drug activated by the NAD(P)H:quinone oxidoreductase (NQO1), an enzyme over-expressed in a large variety of tumors. B-Lap is poorly soluble in water and in most biocompatible solvents. Micellar systems, liposomes and cyclodextrins (CDs) have been proposed for its solubilization. In this work, we analyzed the properties and in vitro efficacy of ß-Lap loaded in polymer nanoparticles, liposome bilayers, complexed with sulfobutyl-ether (SBE)- and hydroxypropyl (HP)-ß cyclodextrins, or double loaded in phospholipid vesicles. Nanoparticles led to the lowest drug loading. Encapsulation of [ß-Lap:CD] complexes in vesicles made it possible to slightly increase the encapsulation rate of the drug in liposomes, however at the cost of poor encapsulation efficiency. Cytotoxicity tests generally showed a higher sensitivity of NIH 3T3 and PNT2 cells to the treatment compared to PC-3 cells, but also a slight resistance at high ß-Lap concentrations. None of the studied ß-Lap delivery systems showed significant enhanced cytotoxicity against PC-3 cells compared to the free drug. Cyclodextrins and double loaded vesicles, however, appeared more efficient drug delivery systems than liposomes and nanoparticles, combining both good solubilizing and cytotoxic properties. Ligand-functionalized double loaded liposomes might allow overcoming the lack of selectivity of the drug.

Hybrid Lipid Polymer Nanoparticles for Combined Chemo- and Photodynamic Therapy.

Retinoblastoma is a malignant tumor of the retina in infants. Conventional therapies are associated to severe side effects and some of them induce secondary tumors. Photodynamic therapy (PDT) thus appears as a promising alternative as it is nonmutagenic and generates minimal side effects. The effectiveness of PDT requires the accumulation of a photosensitizer (PS) in the tumor. However, most porphyrins are hydrophobic and aggregate in aqueous medium. Their incorporation into a nanocarrier may improve their delivery to the cell cytoplasm. In this work, we designed biodegradable liponanoparticles (LNPs) consisting of a poly(d,l)-lactide (PDLLA) nanoparticle coated with a phospholipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-3-trimethylammonium-propane) bilayer. An anticancer drug, beta-lapachone (ß-Lap) and a PS, m-THPC, were co-encapsulated for combined chemo- and PDT because it has been suggested that they may have a synergistic effect based on the activation of ß-Lap by PDT-induced over-expression of the enzyme NQO1. Using dynamic light scattering measurements, cryogenic transmission electron microscopy, and fluorescence confocal microscopy, we selected the appropriate conditions for the encapsulation of the compounds. LNPs were internalized in retinoblastoma cells within few hours. No obvious synergistic effect related to the activation of ß-Lap by PDT was observed. Conversely, the LNPs were cytotoxic at lower doses of the two encapsulated compounds as compared to the single therapies. Analysis of the combinatorial treatment showed that PDT and chemotherapy had an additive effect on the viability of retinoblastoma cells.

Interaction of dequalinium chloride with phosphatidylcholine bilayers: A biophysical study with consequences on the development of lipid-based mitochondrial nanomedicines.

Dequalinium (DQ) has been proposed as a mitochondrial targeting ligand for nanomedicines, including liposomes, given the implication of these organelles in many diseases. This original study focuses on the interactions of DQ with phosphatidylcholine bilayers during the formation of liposomes. Firstly, PEGylated liposomes suitable for drug delivery were studied and were found to be more stable when made in water than in phosphate-buffered saline, emphasizing the role of electrostatic interactions between positive charges on DQ and the polar head groups of the lipids. To gain more information, differential scanning calorimetry, small- and wide-angle X-ray scattering and diffraction, 31P and 2H NMR spectroscopy and freeze-fracture electron microscopy were performed on dimyristoylphosphatidylcholine (DMPC) model membranes in the presence of DQ. This molecule was shown to be located at the level of polar head groups and to induce electrostatic repulsions between adjacent lipid bilayers leading to membrane budding in water. These findings indicate that DQ is not completely inert towards lipid membranes and therefore is not an ideal candidate for encapsulation in liposomes. Overall, our work stresses the necessity for thorough physico-chemical characterization to better understand the mechanisms underlying the development of nanomedicines.

Cancer drug resistance: rationale for drug delivery systems and targeted inhibition of HSP90 family proteins.

Nanocarriers have been developed in order to protect drugs or to improve drugs efficiency by reaching the damaged tissue and avoiding systemic and local toxicity. By using HSP90 inhibitors, some cancer drug resistances have been overcome and the loading into nanocarriers of such drugs has shown an increase of their activities. This review will present some advantages of HSP90 inhibitors to treat resistant tumors; especially those targeting the mitochondrial protein TRAP1. We will also focus on the targeting of the primary tumors, cancer stem cells and metastatic cells.

Antitumor activity of nanoliposomes encapsulating the novobiocin analog 6BrCaQ in a triple-negative breast cancer model in mice.

In this study, we investigated the anticancer efficacy of pegylated liposomes containing 6BrCaQ, an hsp90 inhibitor derived from novobiocin. 6BrCaQ has been previously identified as the most potent compound in a series of quinoleic novobiocin analogs but is poorly water-soluble. We investigated, for the first time, the anti-proliferative effects of this drug in vivo in an orthotopic breast cancer model (MDA-MB-231 luc) using pegylated liposomes to allow its administration. Hsp90, hsp70 and hsp27 protein and mRNA expressions were not strongly affected after treatment meaning it did not induce a heat shock response often associated with resistance and poor prognosis. Liposomal delivery of 6BrCaQ retarded tumor growth at a low dose (1 mg/kg, injected once a week for 4 weeks). Histological analysis of tumors revealed necrosis and a lower proportion of proliferative cells in treated mice indicating that this drug has potential for breast cancer therapy when encapsulated in liposomes.

Heat shock proteins and cancer: How can nanomedicine be harnessed?

Heat shock protein (hsp90) is an interesting target for cancer therapy because it is involved in the folding and stabilization of numerous proteins, including many that contribute to the development of cancer. It is part of the chaperone machinery that includes other heat shock proteins (hsp70, hsp27, hsp40) and is mainly localized in the cytosol, although many analogues or isoforms can be found in mitochondrion, endoplasmic reticulum and the cell membrane. Many potential inhibitors of hsp90 have been tested for cancer therapy but their usefulness is limited by their poor solubility in water and their ability to reach the target cells and the correct intracellular compartment. Nanomedicine, the incorporation of active molecules into an appropriate delivery system, could provide a solution to these drawbacks. In this review, we explain the rationale for using nanomedicine for this sort of cancer therapy, considering the properties of the chaperone machinery and of the different hsp90 analogues. We present some results that have already been obtained and put forward some strategies for delivery of hsp90 analogues to specific organelles.

Surface-Modified Biodegradable Nanoparticles' Impact on Cytotoxicity and Inflammation Response on a Co-Culture of Lung Epithelial Cells and Human-Like Macrophages.

The toxicity of polymeric biodegradable nanoparticles was evaluated on a co-culture made from direct contact of human lung alveolar epithelial cells (A459) and macrophages (differentiated THP-1 monocytes). The co-culture was characterized by its phenotype and by confocal laser scanning microscopy. Cytokine secretion induced by lipopolysaccharide was synergistically increased in the co-culture confirming cell-cell interactions. Poly(lactide-co-glycolide) (PLGA)-based nanoparticles of 200 nm were prepared in presence of hydrophilic polymers commonly used as stabilizers [poly(vinyl alcohol), chitosan and poloxamer 188] through their interaction with particle surface. Stabilizer-free PLGA nanoparticles and stabilizers alone were also evaluated as controls. Selective uptake kinetics of PLGA nanoparticles by cell subpopulations, as well as apoptosis/necrosis detection, was achieved using a specific label for each cell type, while cytokine secretions were quantified in culture supernatants. Both cell subpopulations took up PLGA nanoparticles with similar profiles, and induced only little cytotoxicity (mostly necrosis). A mild inflammatory response to stabilized nanoparticles was detected (compared to well-known inflammatory compounds), slightly higher than the one observed for stabilizer-free PLGA nanoparticles or stabilizing agents taken individually. These results demonstrate that although biodegradable nanoparticles can be considered as safe, they can internalize compounds such as the stabilizing agents which enhance their toxicity.

Formulation and in vitro efficacy of liposomes containing the Hsp90 inhibitor 6BrCaQ in prostate cancer cells.

6BrCaQ is a promising anti-cancer agent derived from novobiocin, which has been shown to inhibit Hsp90. 6BrCaQ was loaded into nanometer-scaled phospholipid vesicles (liposomes) suitable for drug delivery to solid tumors. The effective incorporation of the drug within the phospholipid bilayer was investigated by differential scanning calorimetry. Liposomal 6BrCaQ showed good activity on PC-3 cell lines in vitro in terms of apoptosis induction and cell growth arrest in G2/M. Liposomes containing 6BrCaQ were also shown to slow down migration of PC-3 cells in presence of chemokine ligand 2 and to synergize with doxorubicin. Several Hsp90 targeting molecules like geldanamycin induce accumulation of Hsp70, leading to cytoprotection and often correlated with poor prognosis. In this study, we did not report any Hsp70 induction after treatment with liposomal 6BrCaQ but a decrease in Hsp90 and CDK-4 protein expression, indicating an effect on the chaperon machinery. Liposomal encapsulation of 6BrCaQ revealed promising anti-cancer effects and a better understanding of its mechanism of action.

The Use of Nanocarriers in Acute Myeloid Leukaemia Therapy: Challenges and Current Status.

Chemotherapy for AML is hampered by severe side-effects and failure to eliminate all the blasts that eventually leads to relapse. The use of nanosized particulate drug carriers such as liposomes and polymeric nanoparticles has the potential to improve AML therapy by delivering more of the drug to the disease site, thereby reducing toxicity. For example, encapsulation in liposomes reduces the cardiotoxicity of anthracyclines, giving an improved therapeutic index. Moreover, when the surface properties are engineered appropriately, nanocarriers remain in the circulation and extravasate in tissues with sinusoidal capillaries, one of which is bone marrow, leading to a more favourable distribution of the associated drug. Drug carrier technology contributes to the development of newer drugs, such as nucleic acids that can be protected from degradation and delivered into cells, thus opening the way for gene-silencing strategies. Furthermore, carrier systems provide a means of dispersing poorly water-soluble molecule for in vivo administration and thus increase the "druggability" of new lead compounds, such as heat-shock protein inhibitors. Particulate carriers can transport more than one active agent, allowing synergistic action and theranostic strategies. Notably, phase I and II clinical trials are being performed with CPX-351, a liposomal formulation containing cytarabine and daunorubicin at an optimal ratio. Finally, by attaching suitable ligands to the nanocarrier surface, specific targeting to AML cells can be achieved. In this review, we give examples of successful targeting to folate and transferrin receptors against AML.

Synthesis and antiproliferative activity of novobiocin analogues as potential hsp90 inhibitors.

A series of substituted coumarins1-10 was designed and synthesized as a novel class of 4TCNA analogues. Compound 2a showed excellent antiproliferative activity with mean GI50 values at a micromolar level in a diverse set of human cancer cells (GI50 = 2-30 µM) and induced a high apoptosis level in MCF-7 breast cancer cell line. The molecular signature of hsp90 inhibition was assessed by depletion of the Erα hsp90 client protein.

Epigallocatechin gallate (EGCG) prevents H2O2-induced oxidative stress in primary rat retinal pigment epithelial cells.

PURPOSE: To determine whether the green tea polyphenol epigallocatechin gallate (EGCG) could prevent H(2)O(2)-induced oxidative stress in primary rat retinal pigment epithelial cells. METHODS: Primary cultures of retinal pigment epithelium (RPE) cells were established from Long-Evans newborn rats. RPE cells were pretreated with various concentrations of EGCG for 24 h before being exposed to hydrogen peroxide (H(2)O(2)) for 2 h to induce oxidative stress. Cell metabolic activity was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell death was quantified by flow cytometry using propidium iodide (PI). RESULTS: Treatment of RPE cells with EGCG alone does not affect the cell viability up to 50 µM. Exposure of RPE cells to 600 µM H(2)O(2) caused a significant decrease in cell viability; whereas pretreatment with 10, 25, and 50 µM EGCG significantly reduced this decrease in a dose-dependent manner. The proportion of PI-positive cells increased significantly in cultures treated with H(2)O(2) alone; whereas pretreatment of RPE cells with 50 µM EGCG significantly reduced H(2)O(2)-induced RPE cell death. CONCLUSIONS: Our study shows that EGCG pretreatment can protect primary rat RPE cells from H(2)O(2)-induced death. This suggests potential effect of EGCG in the prevention of retinal diseases associated with H(2)O(2)-induced oxidative stress.

Orange juice and its major polyphenol hesperidin consumption do not induce immunomodulation in healthy well-nourished humans.

BACKGROUND & AIMS: Polyphenols exert a variety of biological properties, including antioxidant, immunomodulatory and antigenotoxic effects. In a randomized crossover study in healthy men, we investigated the effects of orange juice and its major polyphenolic compound hesperidin on a panel of immune cell functions, including cytokine secretion by leukocytes, lytic activity of NK cells, and the Reactive Oxygen Species (ROS) burst by polymorphonuclear neutrophil cells (PMN). METHODS: The protocol design was divided into three 4-week treatment periods separated by 3-week wash-out intervals, for total study duration of 18 weeks. During treatment periods, volunteers (n = 24) consumed daily 500 mL of orange juice, or an isocaloric control beverage with hesperidin (292 mg in a capsule), or of the same control beverage with a placebo. RESULTS: Whatever the intake was, no variations were recorded on leukocyte subset distributions (PMN, B and T lymphocytes, NK cells and monocytes), ROS production by stimulated PMNs, lytic activity of NK cells or cytokine production capacity of leukocytes in well-nourished healthy volunteers. CONCLUSIONS: We show that consumption within the usual daily intake range of orange juice and its major polyphenol hesperidin do not induce immunomodulation of cell immune function in healthy well-nourished humans.

E-selectin as a target for drug delivery and molecular imaging.

E-selectin, also known as CD62E, is a cell adhesion molecule expressed on endothelial cells activated by cytokines. Like other selectins, it plays an important part in inflammation and in the adhesion of metastatic cancer cells to the endothelium. E-selectin recognizes and binds to sialylated carbohydrates present on the surface proteins of certain leukocytes. E-selectin has been chosen as a target for several therapeutic and medical imaging applications, based on its expression in the vicinity of inflammation, infection or cancer. These systems for drug delivery and molecular imaging include immunoconjugates, liposomes, nanoparticles, and microparticles prepared from a wide range of starting materials including lipids, synthetic polymers, polypeptides and organo-metallic structures. After a brief introduction presenting the selectin family and their implication in physiology and pathology, this review focuses on the formulation of these new delivery systems targeting E-selectin at a molecular level.

Altered functions of natural killer cells in response to L-Arginine availability.

L-Arginine (L-Arg) availability is crucial in the regulation of immune response. Indeed, L-Arg deficiency induces T-cell dysfunction and could modulate the properties of natural killer (NK) cells involved in the early host defense against infections and tumors. We explored the impact of L-Arg depletion on NK cell functions using two models - an NK-92 cell line and isolated human blood NK cells. Below 5mg/L of L-Arg, NK-92 cell proliferation was decreased and a total L-Arg depletion reduced NK-92 cell viability. NK cell cytotoxicity was significantly inhibited in presence of low L-Arg concentration (2.5 mg/L). L-Arg depletion reduced the expression of NK-92 activating receptors, NKp46 and NKp30, the expression of NK ζ chain and the NK-92 intracellular production of IFN-γ. Whatever the L-Arg concentrations tested, no significant variation in the gene expression of transporters and enzymes involved in L-Arg metabolism was found. Thus, L-Arg availability modulates the phenotypic and functional properties of NK cells.

Lemon verbena infusion consumption attenuates oxidative stress in dextran sulfate sodium-induced colitis in the rat.

BACKGROUND: Inflammatory bowel diseases (IBD) consist of an uncontrolled intestinal inflammation leading to mucosal disruption. This inflammation is accompanied by an excessive production of reactive oxygen species (ROS). Polyphenols are micronutrients with antioxidative and anti-inflammatory properties, and may play an interesting role in the prevention of intestinal inflammation. Lemon verbena (Aloysia triphylla) infusion is a popular herbal infusion rich in polyphenols (flavones and verbascoside). AIMS: This study evaluated the preventive effects of lemon verbena infusion consumption against mild-to-moderate dextran sulfate sodium (DSS)-induced colitis in rats. METHODS: Wistar rats drank water or lemon verbena infusion for 14 days. On day 15, half of the rats received DSS (4%) in their drink for 7 days. At the end of the experimental period, the colon was taken for histopathological examination and determination of myeloperoxidase (MPO) activity, antioxidant enzyme activities (superoxide dismutase [SOD], glutathione peroxidase [GPx], glutathione reductase [GR], catalase [CAT]), glutathione and lipid peroxidation. Lymphocyte populations were determined in blood, mesenteric nodes and Peyer's patches. RESULTS: Rats ingested daily 5.6 µmol of polyphenols. DSS reduced food intake and induced colitis, as reflected by histological lesions and increased MPO activity. Although these alterations were not significantly counteracted by lemon verbena consumption, the herbal infusion increased colonic SOD activity and decreased lipid peroxidation (malondialdehyde). Other oxidative stress markers (GPx, GR, CAT, glutathione) were not significantly modified. CONCLUSION: Our study shows that the preventive consumption of lemon verbena infusion offered some antioxidative protection during experimental colitis by stimulating SOD activity and decreasing lipid peroxidation.

Liposomal trichostatin A: therapeutic potential in hormone-dependent and -independent breast cancer xenograft models.

BACKGROUND: Trichostatin A (TSA) is one of the most potent histone deacetylase inhibitors (HDACi) in vitro but it lacks biological activity in vivo when injected intravenously owing to its fast metabolism. MATERIALS AND METHODS: TSA was incorporated into Stealth® liposomes (TSA-lipo) at a high loading and its anticancer activity was evaluated in several types of breast cancer cells and xenografts. RESULTS: In estrogen receptor α (ERα)-positive MCF-7 and T47-D cells, TSA induced a long-term degradation of cyclin A and a proteasome-dependent loss of ERα and cyclin D1, allowed derepression of p21WAF1/CIP1, HDAC1 and RhoB GTPase, concomitantly with blockade in G2/M of the cell cycle and apoptosis induction. In MDA-MB-231 (MDA) and SKBr-3 cells, TSA increased ERα mRNA and p21WAF1/CIP1 protein expression, but decreased cyclin A with a G2/M blockade and cleavage of polyADP-ribose polymerase (PARP). No significant restoration of any ER protein was noticed in any cells. TSA-lipo markedly inhibited tumor growth in MCF-7 and MDA cells xenografts following intravenous injection. Their anticancer effects were characterized by inhibition of Ki-67 labeling, the inhibition of tumor vasculature and an increase of p21WAF1/CIP1 in both tumors. In MCF-7 cell tumors, enhanced RhoB accumulation in the cytoplasm of epithelial cells was noticed, inversely to ERα that was strongly decreased. CONCLUSION: Such anticancer activity of TSA-lipo is exp-lained by the protection provided by HDACi encapsulation and by the strong tumor accumulation of the nanocarriers as revealed by fluorescence confocal microscopy experi-ments. Together with its lack of toxicity, the enhanced stability of TSA-lipo in vivo justifies its development for therapeutic use in the treatment estradiol-dependent and -independent breast cancers.