How can a milk protein selectively kill cancer cells? Mechanisms underlying lactoferrin-induced apoptosis

Lactoferrin (Lf) is an iron-binding protein abundant in milk that has been shown to exhibit anticancer activity. Since Lf is non-toxic to cancer cells (1) and is well tolerated in humans (2), this protein has a huge potential to be used in cancer therapy. However, the targets and mechanisms underlying its selective anticancer activity are poorly elucidated, which limits its clinical exploitation. The recruitment of the proton pump V-ATPase to the plasma membrane, where it mediates the acidification of the tumor microenvironment, is a recognized feature involved in the acquisition of a metastatic phenotype in different cancers, including breast cancer. Therefore, inhibitors of this pump have emerged as promising anticancer drugs. Here we show that bovine lactoferrin (bLf) preferentially inhibits cell proliferation and induces apoptosis in two highly metastatic breast cancer cell lines, which display a prominent localization of V-ATPase at the plasma membrane, but not in a lowly metastatic or a non-tumorigenic cell lines (3). We then characterized the mechanism underlying bLf-induced apoptosis and demonstrated that bLf selective cytotoxicity is caused by the inhibition of extracellular acidification rate and the ensuing intracellular acidification in the highly metastatic breast cancer cells. Accordingly, bLf, like the well-known proton pump inhibitors concanamycin A and bafilomycin A1, inhibits V-ATPase proton pumping and hydrolytic activities in sub-cellular fractions enriched in this proton pump. We recently also demonstrated that bLf preferentially induces apoptosis in other types of highly metastatic cancer cells other than breast (4). Altogether, our data demonstrated for the first time that bLf acts as a V-ATPase inhibitor and established a common mechanism of action of bLf against highly metastatic cancer cell exhibiting this proton pump at the plasma membrane. This study opens promising perspectives for the safer and more rational application of bLf in the therapy of these life-threatening cancers. 1. Gibbons JA et al. (2015) BMC Cancer doi: 10.1186/s12885-015-1441-4. 2. Hayes TG et al. (2010) Invest New Drugs doi: 10.1007/s10637-009-9233-9. 3. Pereira CS et al. (2016) Oncotarget doi: 10.18632/oncotarget.11394. 4. Guedes JP et al. (2018) Frontiers in Oncology doi.org/10.3389/fonc.2018.00200info:eu-repo/semantics/publishedVersio

Exploring a novel effect of lactoferrin on the plasma membrane towards the elucidation of the mechanisms of action: from yeast to human cells

Microbiotec'17 - Congress of Microbiology and Biotechnology 2017info:eu-repo/semantics/publishedVersio

Acetic Acid Induces Sch9p-dependent Translocation of Isc1p from the Endoplasmic Reticulum into Mitochondria

Changes in sphingolipid metabolism have been linked to modulation of cell fate in both yeast and mammalian cells. We previously assessed the role of sphingolipids in cell death regulation using a well characterized yeast model of acetic acid-induced regulated cell death, finding that Isc1p, inositol phosphosphingolipid phospholipase C, plays a pro-death role in this process. Indeed, isc1∆ mutants exhibited a higher resistance to acetic acid associated with reduced mitochondrial alterations. Here, we show that Isc1p is regulated by Sch9p under acetic acid stress, since both single and double mutants lacking Isc1p or/and Sch9p have the same resistant phenotype, and SCH9 deletion leads to a higher retention of Isc1p in the endoplasmic reticulum upon acetic acid exposure. We also found that the higher resistance of all mutants correlates with higher levels of endogenous mitochondrial phosphorylated long chain bases (LCBPs), suggesting that changing the sphingolipid balance in favour of LCBPs in mitochondria results in increased survival to acetic acid. In conclusion, our results suggest that Sch9p pathways modulate acetic acid-induced cell death, through the regulation of Isc1p cellular distribution, thus affecting the sphingolipid balance that regulates cell fate

Regulation of cell death induced by acetic acid in yeasts

Acetic acid has long been considered a molecule of great interest in the yeast research field. It is mostly recognized as a by-product of alcoholic fermentation or as a product of the metabolism of acetic and lactic acid bacteria, as well as of lignocellulosic biomass pretreatment. High acetic acid levels are commonly associated with arrested fermentations or with utilization as vinegar in the food industry. Due to its obvious interest to industrial processes, research on the mechanisms underlying the impact of acetic acid in yeast cells has been increasing. In the past twenty years, a plethora of studies have addressed the intricate cascade of molecular events involved in cell death induced by acetic acid, which is now considered a model in the yeast regulated cell death field. As such, understanding how acetic acid modulates cellular functions brought about important knowledge on modulable targets not only in biotechnology but also in biomedicine. Here, we performed a comprehensive literature review to compile information from published studies performed with lethal concentrations of acetic acid, which shed light on regulated cell death mechanisms. We present an historical retrospective of research on this topic, first providing an overview of the cell death process induced by acetic acid, including functional and structural alterations, followed by an in-depth description of its pharmacological and genetic regulation. As the mechanistic understanding of regulated cell death is crucial both to design improved biomedical strategies and to develop more robust and resilient yeast strains for industrial applications, acetic acid-induced cell death remains a fruitful and open field of study. © 2021 Chaves, Rego, Martins, Santos-Pereira, Sousa and Côrte-Real.This work was supported by the "Contrato-Programa" UIDB/04050/2020 funded by national funds through the FCT I.P.info:eu-repo/semantics/publishedVersio

Antibiotic free selection for the high level biosynthesis of a silk-elastin-like protein

Silk-elastin-like proteins (SELPs) are a family of genetically engineered recombinant protein polymers exhibiting mechanical and biological properties suited for a wide range of applications in the biomedicine and materials fields. They are being explored as the next generation of biomaterials but low productivities and use of antibiotics during production undermine their economic viability and safety. We have developed an industrially relevant, scalable, fed-batch process for the high level production of a novel SELP in E. coli in which the commonly used antibiotic selection marker of the expression vector is exchanged for a post segregational suicide system, the separate-component-stabilisation system (SCS). SCS significantly augments SELP productivity but also enhances the product safety profile and reduces process costs by eliminating the use of antibiotics. Plasmid content increased following induction but no significant differences in plasmid levels were discerned when using SCS or the antibiotic selection markers under the controlled fed-batch conditions employed. It is suggested that the absence of competing plasmid-free cells improves host cell viability and enables increased productivity with SCS. With the process developed, 12.8 g L(-1) purified SELP was obtained, this is the highest SELP productivity reported to date and clearly demonstrates the commercial viability of these promising polymers.This work was financed by the European Commission via the 7th Framework Programme Project EcoPlast (FP7-NMP-2009-SME-3), by national funds from the FCT through EXPL/BBB-BIO/1772/2013-FCOMP-010124-FEDER-041595, the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) and a fellowship to SRC (SFRH/BPD/89980/2012), as well as from ERDF through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI). T.C. is supported by the FCT, the European Social Fund, the Programa Operacional Potencial Humano and the Investigador FCT Programme (IF/01635/2014). All the technical staff at the CBMA are thanked for their skilful technical assistance.info:eu-repo/semantics/publishedVersio

A microfluidic platform combined with bacteriophage receptor binding proteins for multiplex detection of Escherichia coli and Pseudomonas aeruginosa in blood

Bloodstream infections (BSIs) are triggered by the existence of pathogens in blood and are considered a major health burden worldwide, especially when they result in sepsis and septic shock. Common diagnostic methods are time-consuming, present low specificity, or suffer from interference of blood components, which hampers a timely and effective treatment of BSIs. In this work, a novel microfluidic assay was developed combining a bead-based chip and bacteriophage receptor binding proteins (RBPs) as extremely specific and sensitive recognition molecules for the multiplex concentration and detection of Escherichia coli and Pseudomonas aeruginosa, which are highly prevalent bacteria in BSIs. The device comprises a microcolumn in which antibody-functionalized agarose beads were packed allowing the entrapment of the target bacterium from blood, providing its concentration and separation. For bacterial detection, two recombinant RBPs (Gp54 and Gp17) were fused with different fluorescent proteins and used for the identification of P. aeruginosa and E. coli by the measurement of the distinct fluorescent signals obtained. The developed microfluidic-based assay enabled a fast (70min) and highly specific multiplex detection of both pathogens in whole blood, achieving a detection limit of around 103 CFU, without requiring any time-consuming bacterial pre-enrichment step. Furthermore, it provided a quantitative assessment of bacterial loads present in blood. Noteworthy, this miniaturized and inexpensive device presents simple fabrication and operation, showing great potential to be fully automated, demonstrating to be ideal in point-of-care settings.The authors acknowledge the funding from the Portuguese Foundation for Science and Technology (FCT) under the scope of the project “Phages‐on‐chip” PTDC/BTM‐SAL/32442/2017 (POCI‐01-0145‐FEDER‐032442) and the strategic funding of the research units CEB (UIDB/04469/2020) and INESC MN (UID/05367/2020) through the pluriannual BASE and PROGRAMATICO financing and BioTecNorte operation (NORTE‐01-0145‐FEDER‐000004) funded by the European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte. S.P.C. and C.R.F.C. acknowledge the FCT for the grants SFRH/BD/130098/2017 and PD/BD/135274/2017, respectively.info:eu-repo/semantics/publishedVersio

Lactoferrin perturbs lipid rafts and requires integrity of Pma1p-lipid rafts association to exert its antifungal activity against Saccharomyces cerevisiae

"Available online 07 January 2021"Lactoferrin (Lf) is a bioactive milk-derived protein with remarkable wide-spectrum antifungal activity. To deepen our understanding of the molecular mechanisms underlying Lf cytotoxicity, the role of plasma membrane ergosterol- and sphingolipid-rich lipid rafts and their association with the proton pump Pma1p was explored. Pma1p was previously identified as a Lf-binding protein. Results showed that bovine Lf (bLf) perturbs sterol-rich lipid rafts organization by inducing intracellular accumulation of ergosterol. Using yeast mutant strains lacking lipid rafts-associated proteins or enzymes involved in the synthesis of ergosterol and sphingolipids, we found that perturbations in the composition of these membrane domains increase resistance to bLf-induced yeast cell death. Also, when Pma1p-lipid rafts association is compromised in the Pma110 mutant and in the absence of the Pma1p-binding protein Ast1p, the bLf killing activity is impaired. Altogether, results showed that the perturbation of lipid rafts and the inhibition of both Pma1p and V-ATPase activities mediate the antifungal activity of bLf. Since it is suggested that the combination of conventional antifungals with lipid rafts-disrupting compounds is a powerful antifungal approach, our data will help to pave the way for the use of bLf alone or in combination for the treatment/eradication of clinically and agronomically relevant yeast pathogens/fungi.This work was supported by national funds through the Portuguese Foundation for Science and Technology (FCT I.P.) under the scope of the strategic funding of “Contrato-Programa” UIDB/04050/2020 and UIDB/ 04469/2020 unit; by the BioTecNorte operation (NORTE-01-0145- FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte; and by the Servicio para el Control de la Esterilización, Laboratorio de Microbiología Oral (CN-16-036). Cátia Santos-Pereira acknowledges the PhD fellowship PD/BD/128032/2016 funded by FCT under the scope of the doctoral programme in Applied and Environmental Microbiology (DP_AEM).info:eu-repo/semantics/publishedVersio

When backscatter communication meets vehicular networks: boosting crosswalk awareness

The research of safety applications in vehicular networks has been a popular research topic in an effort to reduce the number of road victims. Advances on vehicular communications are facilitating information sharing through real time communications, critical for the development of driving assistance systems. However, the communication by itself is not enough to reach the most desired target as we need to know which safety-related information should be disseminated. In this work, we bring passive sensors and backscatter communication to the vehicular network world. The idea is to increase the driver (or vehicle) awareness regarding the presence of pedestrians in a crosswalk. Passive sensors and backscatter communication technologies are used for the pedestrians’ detection phase, while the vehicular network is used during the dissemination of the detection information to surrounding vehicles. The proposed solution was validated through end-to-end experimentation, with real hardware and in a real crosswalk with real pedestrians and vehicles, demonstrating its applicability.info:eu-repo/semantics/publishedVersio

Deciphering the mechanisms underlying bovine milk lactoferrin anticancer activity using yeast and cancer cell lines as complementary models

Lactoferrin (Lf) is a milk derived iron-binding protein that exhibits a broad range of interesting biological activities, from which its anticancer and antifungal activities stand out. Our group has been elucidating the mechanisms and identifying the molecular targets underlying Lf anticancer/antifungal activities in order to improve its therapeutic efficacy and rational application. Indeed, we previously demonstrated that Lf triggers a mitochondrial and caspase-dependent regulated cell death in Saccharomyces cerevisiae (1). Moreover, we found that Lf selectively induces apoptosis in highly metastatic cell lines displaying the proton pump V-ATPase at the plasma membrane (2). However, much work is needed to further characterize Lf mechanisms of action. In the present work, we show how functional genomic approaches using yeast deletion mutants provided new insights on the activity of Lf against yeast that were then validated in human cancer cell lines. Results will be discussed in an integrated manner regarding their contribution towards understanding the molecular basis of Lf anticancer activity. In addition, this study highlights the great potential of yeast as a model to uncover mechanisms of action occurring in the more complex human cells. References (1) Acosta-Zaldívar M, Andrés MT, Rego A, Pereira CS, Fierro JF, Côrte-Real M. (2016) Human lactoferrin triggers a mitochondrial- and caspase-dependent regulated cell death in Saccharomyces cerevisiae. Apoptosis. 21(2):163-73. doi: 10.1007/s10495-015-1199-9. (2) Pereira CS, Guedes JP, Gonçalves M, Loureiro L, Castro L, Gerós H, Rodrigues LR, Côrte-Real M. (2016) Lactoferrin selectively triggers apoptosis in highly metastatic breast cancer cells through inhibition of plasmalemmal V-H+-ATPase. Oncotarget. 7(38):62144-62158. doi: 10.18632/oncotarget.11394.info:eu-repo/semantics/publishedVersio

Cymoxanil inhibits respiration through inhibition of mitochondrial complex IV

Cymoxanil is a synthetic acetamide fungicide, used against oomycetes. It was first introduced in 1977 and can be used against downy mildew diseases induced by Plasmopara viticola in grapevine cultures and late blight diseases caused by Phytophthora infestans, in tomatoes and potatoes cultures. This fungicide is used in mixed formulations and its higher solubility enables a relatively widespread occurrence in toxic concentrations in aquatic environments. Although it has been used over the years, its biochemical mode of action is not yet known. Some studies reported that cymoxanil affects growth, respiration, DNA, RNA and protein synthesis and RNA polymerase activity of Phytophthora infestans, and it was reported to inhibit cell growth and biomass production and decrease the respiration rate of S. cerevisiae. Using yeast S. cerevisiae as model, we further characterized its effect on mitochondria. We found that whole cells treated with cymoxanil present a higher inhibition of oxygen consumption after 3 h of treatment that remains over time. Using isolated mitochondria, we observe that cymoxanil inhibits respiratory rate of yeast cells by inhibiting oxidative phosphorylation, through inhibition of complex IV activity. Although other targets cannot be excluded, our data provide new information about mode of action of cymoxanil that can be instrumental to drive informed management regarding the use of this fungicide.info:eu-repo/semantics/publishedVersio