Multimeric Presentation of RGD Peptidomimetics Enhances Integrin Binding and Tumor Cell Uptake.

The use of multimeric ligands is considered as a promising strategy to improve tumor targeting for diagnosis and therapy. Herein, tetrameric RGD (Arg-Gly-Asp) peptidomimetics were designed to target αv ß3 integrin-expressing tumor cells. These compounds were prepared by an oxime chemoselective assembly of cyclo(DKP-RGD) ligands and a cyclodecapeptide scaffold, which allows a tetrameric presentation. The resulting tetrameric RGD peptidomimetics were shown to improve αv ß3 integrin binding compared with the monomeric form. Interestingly, these compounds were also able to enhance tumor cell endocytosis in the same way as tetrameric RGD peptides. Altogether, the results show the potential of the tetrameric cyclo(DKP-RGD) ligands for in vivo imaging and drug delivery.

Synthesis and Biological Characterization of Monomeric and Tetrameric RGD-Cryptophycin Conjugates.

The effective delivery of cytotoxic agents to tumor cells is a key challenge in anticancer therapy. Multivalent integrinspecific ligands are considered a promising tool to increase the binding affinity, selectivity, and internalization efficiency of small-molecule drug conjugates. Herein, we report the synthesis and biological evaluation of a multimeric conjugate containing the high-affinity integrin αv ß3 binding ligand RAFT-c(RGDfK)4 , a lysosomally cleavable Val-Cit linker, and cryptophycin-55 glycinate, a potent inhibitor of tubulin polymerization. In vitro cytotoxicity assays verified that the multimeric RGD-cryptophycin conjugate displays improved potency compared to the monomeric analogue in integrin αv ß3 overexpressing tumor cell lines, while significantly reduced activity was observed in the integrin-negative cell line.

Cadmium-induced apoptosis in the BJAB human B cell line: involvement of PKC/ERK1/2/JNK signaling pathways in HO-1 expression.

Heme oxygenase-1 (HO-1, EC 1.14.99.3) is a key enzyme in the cellular response to tissue injury and oxidative stress. It oxidizes heme, a pro-oxidant and toxic species, to biliverdin, CO, and free iron. Cytoprotection during the heat shock response is a complex phenomenon involving multiple inducible mechanisms. Several important pathways involving serine/threonine kinases mediate the induction of HO-1 in response to external stimuli. The objective of the present study was to investigate the mechanism of HO-1 induction during cadmium (Cd)-induced oxidative stress and apoptosis in the lymphocyte B cell line BJAB. To examine the signal pathways involved in HO-1 expression, cells were pre-treated with various inhibitors of key signaling molecules. Increased DNA fragmentation and caspase-3 activity were observed in BJAB cells exposed to 5-40 µM CdCl(2) revealing that Cd induced apoptosis in these cells. Our results indicate that Cd also induces HO-1 expression which is modulated by the thiol redox status, tyrosine kinase and PI3-kinase. The inhibitory effect of calphostin C suggests that Cd induction of HO-1 expression could be mediated by the PKC pathway in the BJAB cells together with the involvement of ERK ½ and JNK in a dose-dependent manner. The molecular and cellular pathways should not be considered separately. They should be viewed as an array of interconnecting signals, all contributing to the final outcome, thereby allowing fine control of the duration and extent of HO-1 induction.

Structural requirement of arylindolylpropenones as anti-bladder carcinoma cells agents.

Chalcones have been identified as interesting compounds with cytotoxicity, anti-inflammatory and antioxidant properties. In the present study, we report the synthesis and evaluation of new 1-(N-methylindolyl)-3-phenylpropenones as anti-cancer agents acting on bladder carcinoma cell line. Among the 15 investigated molecules, three of them inhibit the growth of bladder cancer cells with IC(50) values less than 4 µM after 48 h of treatment. To investigate their mode of action, cell cycle analyses were performed. The most active compounds induce high accumulation at the G2+M phase as assessed by flow cytometry. The structure-activity relationship drawn from the present study highlights the importance of the substitution pattern of the phenyl ring and provides valuable information for further development of this class of compounds as novel anti-cancer chemotherapeutic agents.

Cadmium chloride-induced oxidative stress and DNA damage in the human Jurkat T cell line is not linked to intracellular trace elements depletion.

Cadmium (Cd) is a widespread environmental contaminant. Cd affects the cellular homeostasis and generates damage via complex mechanisms involving interactions with other metals, induction of oxidative stress and apoptotic or necrotic cell death, depending on the cell type and the concentration. The goal of the present study was to investigate the effect of exposure to CdCl(2) on the intracellular trace elements levels, the antioxidant enzyme activities and on DNA damage in the Jurkat T cell line. Cells were exposed to 5, 25 and 50 µM of CdCl(2) for 24 h. Cd significantly reduced the viability of Jurkat T cells and induced a dose-dependent increase in DNA damage with statistically significant differences relative to controls (p<0.001); the superoxide dismutase and glutathione peroxidase activities were significantly decreased. Lipid peroxidation and protein carbonyl levels were significantly increased while glutathione and the total intracellular sulfhydryl groups were decreased showing clearly that an oxidative stress was generated by Cd. Surprisingly the treatment with Cd induced a significant increase in the intracellular levels of all the trace elements measured. The results indicate that cellular pro-oxidative stress induced by Cd is most likely mediated by disruption of redox homeostasis associated to a mishandling of redox-active transition metals and causes lipid and protein oxidation and oxidative DNA damage in Jurkat T cells.

In vitro antioxidant and antigenotoxic potentials of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside from Myrtus communis: modulation of expression of genes involved in cell defence system using cDNA microarray.

Antioxidant activity of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside, isolated from the leaves of Myrtus communis, was determined by the ability of each compound to inhibit xanthine oxidase activity, lipid peroxidation and to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl. Antimutagenic activity was assessed using the SOS chromotest and the Comet assay. The IC50 values of lipid peroxidation by myricetin-3-o-galactoside and myricetin-3-o-rhamnoside are respectively 160 microg/ml and 220 microg/ml. At a concentration of 100 microg/ml, the two compounds showed the most potent inhibitory effect of xanthine oxidase activity by respectively, 57% and 59%. Myricetin-3-o-rhamnoside was a very potent radical scavenger with an IC50 value of 1.4 microg/ml. Moreover, these two compounds induced an inhibitory activity against nifuroxazide, aflatoxine B1 and H2O2 induced mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress using a cDNA micro-array. Myricetin-3-o-galactoside and myricetin-3-o-rhamnoside modulated the expression patterns of cellular genes involved in oxidative stress, respectively (GPX1, TXN, AOE372, SEPW1, SHC1) and (TXNRD1, TXN, SOD1 AOE372, SEPW1), in DNA damaging repair, respectively (XPC, LIG4, RPA3, PCNA, DDIT3, POLD1, XRCC5, MPG) and (TDG, PCNA, LIG4, XRCC5, DDIT3, MSH2, ERCC5, RPA3, POLD1), and in apoptosis (PARP).

Study of antimutagenic and antioxidant activities of gallic acid and 1,2,3,4,6-pentagalloylglucose from Pistacia lentiscus. Confirmation by microarray expression profiling.

In vitro antioxidant and antimutagenic activities of two polyphenols isolated from the fruits of Pistacia lentiscus was assessed. Antioxidant activity was determined by the ability of each compound to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH*), to inhibit xanthine oxidase and to inhibit the lipid peroxidation induced by H(2)O(2) in K562 cell line. Antimutagenic activity was assayed with SOS chromotest using Escherichia coli PQ37 as tester strain and Comet assay using K562 cell line. 1,2,3,4,6-Pentagalloylglucose was found to be more effective to scavenge DPPH* radical and protect against lipid peroxidation. Moreover, these two compounds induced an inhibitory activity against nifuroxazide and aflatoxin B1 mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress. For this purpose, we used a cDNA-microarray containing 82 genes related to cell defense, essentially represented by antioxidant and DNA repair proteins. We found that 1,2,3,4,6-pentagalloylglucose induced a decrease in the expression of 11 transcripts related to antioxidant enzymes family (GPX1, TXN, AOE372, SHC1 and SEPW1) and DNA repair (POLD1, APEX, POLD2, MPG, PARP and XRCC5). The use of Gallic acid, induced expression of TXN, TXNRD1, AOE372, GSS (antioxidant enzymes) and LIG4, POLD2, MPG, GADD45A, PCNA, RPA2, DDIT3, HMOX2, XPA, TDG, ERCC1 and GTF2H1 (DNA repair) as well as the repression of GPX1, SEPW1, POLD1 and SHC1 gene expression.