Cell-cell communication in metastatic breast cancer: a control point that can lead to breast cancer treatment

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Protonectin peptides target lipids, act at the interface and selectively kill metastatic breast cancer cells while preserving morphological integrity

Publication . Batista Martins, Danubia; Fadel, Valmir; Oliveira, Filipa D.; Gaspar, Diana; Alvares, Dayane S.; Castanho, Miguel A. R. B.; Dos Santos Cabrera, Marcia Perez

Despite the need for innovative compounds as antimicrobial and anticancer agents, natural sources of peptides remain underexplored. Protonectin (PTN), a cationic dodecapeptide of pharmacological interest, presents large hydrophobicity that is associated with the tendency to aggregate and supposedly influences bioactivity. A disaggregating role was assigned to PTN' N-terminal fragment (PTN1-6), which enhances the bioactivity of PTN in a 1:1 mixture (PTN/PTN1-6). Spectroscopic techniques and model membranes (phospholipid bilayers and SDS micelles) revealed that environment-dependent aggregation is reduced for PTN/PTN1-6, but cytotoxicity of PTNs on MDA-MB-231 breast cancer showed the same CC50 values around 16 µM and on MCF-10A epithelial breast cells 6 to 5-fold higher values, revealing a selective interaction. Since PTN1-6 lacks activity on breast cells, its presence should differently affect PTN activity, suggesting that aggregation could modulate activity depending on the membrane characteristics. Indeed, increased partitioning and lytic activity of PTN/PTN1-6 were found in model membranes independently of charge density, but affected by the curvature tendency. PTN and PTN/PTN1-6 do not alter morphology and roughness of cancer cells, indicating a superficial interaction with membranes and consistent with results obtained in NMR experiments. Our results indicate that aggregation of PTNs depends on the membrane characteristics and modulates the activity of the peptides.

2021-05-25Journal article

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Synthesis, structure, and activity of the antifungal plant defensin PvD1

Publication . Skalska, Julia; Andrade, Vitor M.; Cena, Gabrielle L.; Harvey, Peta J.; Gaspar, Diana; Mello, Érica O.; Henriques, Sónia T.; Valle, Javier; Gomes, Valdirene M.; Conceição, Katia; Castanho, Miguel A. R. B.; Andreu, David

Available treatments for invasive fungal infections have limitations, including toxicity and the emergence of resistant strains. Therefore, there is an urgent need for alternative solutions. Because of their unique mode of action and high selectivity, plant defensins (PDs) are worthy therapeutic candidates. Chemical synthesis remains a preferred method for the production of many peptide-based therapeutics. Given the relatively long sequence of PDs, as well as their complicated posttranslational modifications, the synthetic route can be considered challenging. Here, we describe a total synthesis of PvD1, the defensin from the common bean Phaseolus vulgaris. Analytical, structural, and functional characterization revealed that both natural and synthetic peptides fold into a canonical CSαβ motif stabilized by conserved disulfide bonds. Moreover, synthetic PvD1 retained the biological activity against four different Candida species and showed no toxicity in vivo. Adding the high resistance of synthetic PvD1 to proteolytic degradation, we claim that conditions are now met to consider PDs druggable biologicals.

2020Journal article

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Challenging metastatic breast cancer with the natural defensin PvD1

Publication . Figueira, Tiago N.; Oliveira, Filipa D.; Almeida, Inês; Mello, Érica O.; Gomes, Valdirene M.; Castanho, Miguel A. R. B.; Gaspar, Diana

Metastatic breast cancer is a very serious life threatening condition that poses many challenges for the pharmaceutical development of effective chemotherapeutics. As the therapeutics targeted to the localized masses in breast improve, metastatic lesions in the brain slowly increase in their incidence compromising successful treatment outcomes overall. The blood-brain-barrier (BBB) is one important obstacle for the management of breast cancer brain metastases. New therapeutic approaches are in demand for overcoming the BBB's breaching by breast tumor cells. In this work we demonstrate the potential dual role of a natural antimicrobial plant defensin, PvD1: it interferes with the formation of solid tumors in the breast and concomitantly controls adhesion of breast cancer cells to human brain endothelial cells. We have used a combination of techniques that probe PvD1's effect at the single cell level and reveal that this peptide can effectively damage breast tumor cells, leaving healthy breast and brain cells unaffected. Results suggest that PvD1 quickly internalizes in cancer cells but remains located in the membrane of normal cells with no significant damage to its structure and biomechanical properties. These interactions in turn modulate cell adhesiveness between tumor and BBB cells. PvD1 is a potential template for the design of innovative pharmacological approaches for metastatic breast cancer treatment: the manipulation of the biomechanical properties of tumor cells that ultimately prevent their attachment to the BBB.

2017Journal article

Open access

Scalable production of human mesenchymal stromal cell-derived extracellular vesicles under serum-/xeno-free conditions in a microcarrier-based bioreactor culture system

Publication . Fuzeta, Miguel de Almeida; Bernardes, Nuno; Oliveira, Filipa D.; Costa, Ana Catarina; Fernandes-Platzgummer, Ana; Farinha, José Paulo; Rodrigues, Carlos A.V.; Jung, Sunghoon; Tseng, Rong-Jeng; Milligan, William; Lee, Brian; Castanho, Miguel A. R. B.; Gaspar, Diana; Cabral, Joaquim M.S.; da Silva, Cláudia Lobato

Mesenchymal stromal cells (MSC) hold great promise for tissue engineering and cell-based therapies due to their multilineage differentiation potential and intrinsic immunomodulatory and trophic activities. Over the past years, increasing evidence has proposed extracellular vesicles (EVs) as mediators of many of the MSC-associated therapeutic features. EVs have emerged as mediators of intercellular communication, being associated with multiple physiological processes, but also in the pathogenesis of several diseases. EVs are derived from cell membranes, allowing high biocompatibility to target cells, while their small size makes them ideal candidates to cross biological barriers. Despite the promising potential of EVs for therapeutic applications, robust manufacturing processes that would increase the consistency and scalability of EV production are still lacking. In this work, EVs were produced by MSC isolated from different human tissue sources [bone marrow (BM), adipose tissue (AT), and umbilical cord matrix (UCM)]. A serum-/xeno-free microcarrier-based culture system was implemented in a Vertical-WheelTM bioreactor (VWBR), employing a human platelet lysate culture supplement (UltraGROTM-PURE), toward the scalable production of MSC-derived EVs (MSC-EVs). The morphology and structure of the manufactured EVs were assessed by atomic force microscopy, while EV protein markers were successfully identified in EVs by Western blot, and EV surface charge was maintained relatively constant (between −15.5 ± 1.6 mV and −19.4 ± 1.4 mV), as determined by zeta potential measurements. When compared to traditional culture systems under static conditions (T-flasks), the VWBR system allowed the production of EVs at higher concentration (i.e., EV concentration in the conditioned medium) (5.7-fold increase overall) and productivity (i.e., amount of EVs generated per cell) (3-fold increase overall). BM, AT and UCM MSC cultured in the VWBR system yielded an average of 2.8 ± 0.1 × 1011, 3.1 ± 1.3 × 1011, and 4.1 ± 1.7 × 1011 EV particles (n = 3), respectively, in a 60 mL final volume. This bioreactor system also allowed to obtain a more robust MSC-EV production, regarding their purity, compared to static culture. Overall, we demonstrate that this scalable culture system can robustly manufacture EVs from MSC derived from different tissue sources, toward the development of novel therapeutic products.

2020Journal article

Open access

Cell membrane composition drives selectivity and toxicity of designed cyclic helix−loop−helix peptides with cell penetrating and tumor suppressor properties

Publication . Philippe, Grégoire J.-B.; Gaspar, Diana; Sheng, Caibin; Huang, Yen-Hua; Benfield, Aurélie H.; Condon, Nicholas D.; Weidmann, Joachim; Lawrence, Nicole; Löwer, Alexander; Castanho, Miguel A. R. B.; Craik, David J.; Henriques, Sónia Troeira

The tumor suppressor protein p53 is inactive in a large number of cancers, including some forms of sarcoma, breast cancer, and leukemia, due to overexpression of its intrinsic inhibitors MDM2 and MDMX. Reactivation of p53 tumor suppressor activity, via disruption of interactions between MDM2/X and p53 in the cytosol, is a promising strategy to treat cancer. Peptides able to bind MDM2 and/or MDMX were shown to prevent MDM2/X:p53 interactions, but most possess low cell penetrability, low stability, and/or high toxicity to healthy cells. Recently, the designed peptide cHLH-p53-R was reported to possess high affinity for MDM2, resistance toward proteases, cell-penetrating properties, and toxicity toward cancer cells. This peptide uses a stable cyclic helix−loop−helix (cHLH) scaffold, which includes two helices connected with a Gly loop and cyclized to improve stability. In the current study, we were interested in examining the cell selectivity of cHLH-p53-R, its cellular internalization, and ability to reactivate the p53 pathway. We designed analogues of cHLH-p53-R and employed biochemical and biophysical methodologies using in vitro model membranes and cell-based assays to compare their structure, activity, and mode-of-action. Our studies show that cHLH is an excellent scaffold to stabilize and constrain p53-mimetic peptides with helical conformation, and reveal that anticancer properties of cHLH-p53-R are mediated by its ability to selectively target, cross, and disrupt cancer cell membranes, and not by activation of the p53 pathway. These findings highlight the importance of examining the mode-of-action of designed peptides to fully exploit their potential to develop targeted therapies.

2019Journal article

Restricted access