Cell-Penetrating Peptides: A Challenge for Drug Delivery

Cell-penetrating peptide (CPP) is a term that describes relatively short amphipathic and cationic peptides (7–30 amino acid residues) with rapid translocation across the cell membrane. They can be used to deliver molecular bioactive cargoes due to their efficacy in cellular internalization and also to their low cytotoxicity. In this review we provide an overview of the current approaches and describe the potential of CPP-based drug delivery systems and indicate their powerful promise for clinical efficacy

COUPLAGE DE PEPTIDES DE PENETRATION CELLULAIRE A UN AGENT ANTI-TUMORAL ET EVALUATION DE L'EFFICACITE DES COMPLEXES

The transport of substances equiped with pharmacological properties through the plasma membrane and their access to the various intracellular compartments, in particular the cytoplasm and the nuclei, remains an obstacle for biotechnological and biomedical research and pharmaceutical industry. Among the currently known means to introduce substances into cells, the peptides of translocation also called CPPs (Cell- Penetrating-Peptides) which represent a particularly interesting vector. In this work, we used three CPPs, Tat, penétratine and an analogue of the maurocalcine (MCa Abu ) for the delivery of the doxorubicine (Dox), a drug used in anti-cancer chemotherapy and which its effect is limited by the resistance of tumoral cells. In order to evaluate the effectiveness of the three formed complexes (Dox-CPPs), two cellular models of mammalian cancer were used; MDA-MB 231 cells and MCF7 cells which have different sensitivity to the drug alone. Our study enabled us to show initially that the three CPPs used represent powerful vectors for the translocation of the Dox inside the cells and that the conjugation of drug circumvented the resistance of MDA-MB 231 cells to Dox. We also showed that the distribution of free Dox is rather nuclear when unconjugated and cytoplasmic when it is conjugated to CPPs. In the second part of our work, we showed that Dox as well as Dox-CPPs induce the apoptosis of MDA-MB 231 cells and that this effect is observed by treating the cells with an amount five times weaker of Dox-CPPs compared to Dox.. This death is dependent on caspases and implies the mitochondrial way. Moreover, the apoptosis induced by Dox is mediated by the reactive oxygen spices (ROS). Those are partly implied in the apoptosis induced by Dox-CPPs since the use of an inhibitor of ROS partially inhibits the apoptosis induced by these compounds. We also showed that the surexpression of Bcl-2 protects the apoptosis induced by Dox and partially by Dox-CPPs, which suggests that another way is implied in the apoptosis induced by Dox-CPPs and who would explain the strongest toxicity of these compounds. Concerning this second way we could shown that the TRAIL death receptors are well implied in the apoptosis induced by Dox-CPPs via the membrane capping of the of d DR4 and DR5 receptors. This capping modifies the rate of expression of these membrane receivers and in the origin of sensitizing MDA-MB 231 cells with the endogenous TRAIL during the apoptosis induced by Dox-CPPs. Such a sensitizing with the TRAIL is at the origin of the céramide generation, which constitutes another way of induction of apoptose by Dox-CPPs in addition to the mitochondrial way. The whole of these results should enable us to develop a strategy of coupling of CPPs to antitumor agents in order to improve their effect and to better understand the ways of indication of the death induced following the coupling. This could in the long term lead to the design of new analogues of higher therapeutic index Key words: Cell- Penetrating-Peptides, doxorubicin, cellular resistance, apoptosis, ROS, death receptors, ceramide.Le transport de substances dotées de propriétés pharmacologiques au travers de la membrane plasmique ainsi que leur accès aux divers compartiments intracellulaires, en particulier le compartiment cytoplasmique et nucléaire, demeure un obstacle pour la recherche biotechnologique et biomédicale et pour l'industrie pharmaceutique. Parmi les moyens actuellement connus pour introduire des substances dans les cellules, les peptides de translocation également dénommés CPPs (Cell- Penetrating-Peptides) qui représentent des vecteurs particulièrement intéressants. Dans le présent travail, nous avons utilisé trois CPPs, Tat, penétratine et un analogue de la maurocalcine (MCaAbu) pour la délivrance de la doxorubicine (Dox), une drogue utilisée en chimiothérapie anticancéreuse et dont son effet est limité par la résistance des cellules tumorales. Afin d'évaluer l'efficacité des trois complexes formés (Dox-CPPs), deux modèles cellulaires du cancer mammaire ont été utilisés; les cellules MDA-MB 231 et les cellules MCF7 qui présentent une sensibilité différente à la drogue seule. Notre étude nous a permis de monter en premier lieu que les trois CPPs utilisés représentent de puissants vecteurs pour l'entrée de la Dox à l'intérieur des cellules et que la conjugaison de la drogue a contourné la résistance des cellules MDA-MB 231 à la Dox. Nous avons également montré que la distribution de la Dox est plutôt nucléaire à l'état libre et cytoplasmique lorsqu'elle est couplée aux CPPs. Dans la deuxième partie de notre travail, nous avons montré que la Dox ainsi que les Dox-CPPs induisent l'apoptose des cellules MDA-MB 231 et que cet effet est observé en traitant les cellules avec une dose cinq fois plus faible de Dox-CPPs par rapport à la Dox. Cette mort est dépendante des caspases et implique la voie mitochondriale. De plus, l'apoptose induite par la Dox est médiée par les radicaux oxygénés (ROS). Ceux-ci sont en partie impliqués lors de l'apoptose induite par les Dox-CPPs puisque l'utilisation d'un inhibiteur de ROS inhibe partiellement l'apoptose induite par ces composés. Nous avons montré également que la surexpression de Bcl-2 protège l'apoptose induite par la Dox et partiellement par les Dox-CPPs, ce qui suggère qu'une autre voie est impliquée dans l'apoptose induite par les Dox-CPPs et qui expliquerait la plus forte toxicité de ces composés. Concernant cette deuxième voie nous avons pu montré que les récepteurs de mort TRAIL sont bien impliqués dans l'apoptose induite par les Dox-CPPs via la clustérisation membranaire des récepteurs de mort DR4 et DR5. Cette clustérisation modifie le taux d'expression de ces récepteurs membranaires et à l'origine d'une sensibilisation des cellules MDA-MB 231 au TRAIL endogène au cours de l'apoptose induite par les Dox-CPPs. Une telle sensibilisation au TRAIL est à l'origine de la génération de céramide, qui constitue une autre voie d'induction d'apoptose par les Dox-CPPs en plus de la voie mitochondriale. L'ensemble de ces résultats devraient nous permettre à valoriser la stratégie de couplage des CPPs à des agents antitumoraux afin d'améliorer leur effet et de mieux comprendre les voies de signalisation de la mort induite suite au couplage. Ceci pourrait à terme conduire à la conception de nouveaux analogues d'index thérapeutique plus élevé. Mots clés : Cell- Penetrating-Peptides, Doxorubicine, résistance cellulaire, apoptose, ROS, récepteurs de mort, céramide

Cytotoxicity, intracellular distribution and uptake of doxorubicin and doxorubicin coupled to cell-penetrating peptides in different cell lines: a comparative study.

International audienceOne of the major obstacles which are opposed to the success of anticancer treatment is the cell resistance that generally develops after administration of commonly used drugs. In this study, we try to overcome the tumour cell resistance of doxorubicin (Dox) by developing a cell-penetrating peptide (CPP)-anticancer drug conjugate in aim to enhance its intracellular delivery and that its therapeutic effects. For this purpose, two cell-penetrating peptides, penetratin (pene) and tat, derived from the HIV-1 TAT protein, were chemically conjugated to Dox. The cytotoxicity, intracellular distribution and uptake were accessed in CHO cells (Chinese Hamster Ovarian carcinoma cells), HUVEC (Human Umbilical Vein Endothelial Cells), differentiated NG108.15 neuronal cell and breast cancer cells MCF7drug-sensitive or MDA-MB 231 drug-resistant cell lines. The conjugates showed different cell killing activity and intracellular distribution pattern by comparison to Dox as assessed respectively by MTT-based colorimetric cellular cytotoxicity assay, confocal fluorescence microscopy and FACS analysis. After treatment with 3 microM with Dox-CPPs for 2h, pene increase the Dox cytotoxicity by 7.19-fold in CHO cells, by 11.53-fold in HUVEC cells and by 4.87-fold in MDA-MB 231 cells. However, cytotoxicity was decreased in NG108.15 cells and MCF7. Our CPPs-Dox conjugate proves the validity of CPPs for the cytoplasmic delivery of therapeutically useful molecules and also a valuable strategy to overcome drug resistance

Efficient induction of apoptosis by doxorubicin coupled to cell-penetrating peptides compared to unconjugated doxorubicin in the human breast cancer cell line MDA-MB 231.

International audienceDoxorubicin (Dox) is a commonly used drug to treat various types of cancers. Previously, we demonstrated that coupling Dox to cell-penetrating peptides (CPPs) represent a valuable strategy to overcome drug resistance in MDA-MB 231 breast cancer cells. In the present study, we evaluated the properties of these Dox conjugates (Dox-CPPs) in terms of apoptosis induction. Dox-CPPs were found to induce apoptotic death in MDA-MB 231 cells at a lower dose than that needed for unconjugated Dox. Cell death induction was associated with Bax oligomerisation, release of cytochrome c, caspase activation, chromatin condensation and internucleosomal degradation. However, whereas Bcl-2 overexpression was very potent in inhibiting apoptosis triggered by Dox, this anti-apoptotic protein was largely inefficient in preventing Dox-CPPs-induced apoptosis. These observations suggest that mitochondrial disruption is the main event in Dox-induced apoptotic signaling but that Dox-CPPs are probably able to trigger additional apoptotic pathways independent of mitochondrial events. Thus, the higher efficacy of Dox conjugated to CCPs in apoptosis induction might not be due exclusively to increased drug accumulation but also to the activation of multiple apoptotic pathways

Doxorubicin coupled to penetratin promotes apoptosis in CHO cells by a mechanism involving c-Jun NH2-terminal kinase.

International audienceDoxorubicin (Dox) has demonstrated potent activity in treating malignant lymphomas but its therapeutic efficacy is hampered by induction of cardiotoxicity. This side effect is related to the ability of the drug to generate reactive oxygen species in cells. Previously, we demonstrated that coupling Dox to penetratin (Pen), a cell penetrating peptide, represent a valuable strategy to overcome drug resistance in CHO cells. In the present study, we evaluated the consequences of the conjugation of Dox to Pen in term of apoptosis induction. When tested on CHO cells, Dox-Pen generated a typical apoptotic phenotype but at lower dose that needed for unconjugated Dox. Cell death induction was associated with chromatin condensation, caspase activation, Bax oligomerisation and release of cytochrome c. By using reactive oxygen species and c-jun NH2-terminal kinase (JNK) inhibitors, we prevented Dox- and Dox-Pen-induced CHO cell death. The chimeric soluble DR5 receptor that inhibits TRAIL induced cell death does not prevent Dox or Dox-Pen-induced cytotoxicity. These observations indicate that conjugation of Dox to cell penetrating peptide does not impair the ability of the drug to trigger cell death through activation of the intrinsic pathway involving c-Jun NH2-terminal kinase but could exhibit less toxic side effects and could warrant its use in clinic

The combination of Bleomycin with TRAIL agonists or PKC inhibitors sensitizes solid tumor cells to BLM-mediated apoptosis: new strategies to overcome chemotherapy resistance of tumors

IF 1.436International audienceIn 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

Conjugation of doxorubicin to cell penetrating peptides sensitizes human breast MDA-MB 231 cancer cells to endogenous TRAIL-induced apoptosis.

International audiencePrevious work from our laboratory has shown that coupling doxorubicin (Dox) to cell penetrating peptides (Dox-CPPs) is a good strategy to overcome Dox resistance in MDA-MB 231 breast cancer cells. We also reported that, in contrast to unconjugated Dox-induced cell death, the increase in apoptotic response does not involve the mitochondrial apoptotic pathway. In this study, we demonstrate that both Dox and Dox-CPPs can increase the density of the TRAIL receptors DR4 and DR5 at the plasma membrane and moderately sensitize MDA-MB 231 cells to exogeneously added recombinant TRAIL, as has already been shown for other chemotherapeutic drugs. Moreover, we show that Dox-CPPs, used alone, induce the clustering of TRAIL receptors into ceramide-enriched membrane lipid rafts, a property not shared by unconjugated Dox and that this process is due to the generation of ceramide during Dox-CPPs treatment. In addition, MDA-MB 231 cells were found to express TRAIL and we show that the increased apoptotic rate induced by Dox-CPPs is due to the sensitization of MDA-MB 231 cells to endogenous TRAIL. The capacity of Dox-CPPs to sensitize cancer cells to physiologic amounts of TRAIL suggests that, in addition to their efficiency in combination chemotherapy, these compounds might increase the response of tumor cells to cytotoxic lymphocyte-mediated killing via TRAIL

Analysis of the Coloring and Antibacterial Effects of Natural Dye: Pomegranate Peel

This work aims to conduct an eco-friendly textile finishing process by applying agricultural by-products as a dye for the finishing of polyamide fabrics. A natural dye was obtained from pomegranate peel extract. Polyamide fabrics were dyed at different conditions, and four mordanting agents were tested. The finished fabrics were analyzed in terms of CIE L, a, b and color yield (K/S) values, as well as washing fastness, rubbing fastness, light fastness and antibacterial activity. Results show that pomegranate peel extract could dye polyamide fabrics. The rubbing and washing fastness of the finished samples was good. The light fastness was fair, and its antibacterial efficiency against the tested bacteria was good

Design of a disulfide-less, pharmacologically inert, and chemically competent analog of maurocalcine for the efficient transport of impermeant compounds into cells.

International audienceMaurocalcine is a 33-mer peptide initially isolated from the venom of a Tunisian scorpion. It has proved itself valuable as a pharmacological activator of the ryanodine receptor and has helped the understanding of the molecular basis underlying excitation-contraction coupling in skeletal muscles. Because of its positively charged nature, it is also an innovative vector for the cell penetration of various compounds. We report a novel maurocalcine analog with improved properties: (i) the complete loss of pharmacological activity, (ii) preservation of the potent ability to carry cargo molecules into cells, and (iii) coupling chemistries not affected by the presence of internal cysteine residues of maurocalcine. We did this by replacing the six internal cysteine residues of maurocalcine by isosteric 2-aminobutyric acid residues and by adding an additional N-terminal biotinylated lysine (for a proof of concept analog) or an N-terminal cysteine residue (for a chemically competent coupling analogue). Additional replacement of a glutamate residue by alanyl at position 12 further improves the potency of these analogues. Coupling to several cargo molecules or nanoparticles are presented to illustrate the cell penetration potency and usefulness of these pharmacologically inactive analogs