A fish antimicrobial peptide, tilapia hepcidin TH2-3, shows potent antitumor activity against human fibrosarcoma cells

Bacterial infection-biased abundance of proteins in the skin mucus of obscure puffer (Takifugu Obscurus)

The skin mucus of fish is equipped with immunological and antimicrobial peptides that confer protection against invading pathogens. The skin mucus has been studied in fish however information regarding its immunological roles in bacterial infection is rare. This study highlighted the proteins and peptides in the skin mucus of Obscure puffer Takifugu obscurus that quantitatively altered against Aeromonas hydrophila infection. We infected the fish through bath immersion, intraperitonially, and treated with PBS (control) then compared the level of proteins in the skin mucus among the groups using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The Tandem Mass Tag (TMT) based quantification showed that 4896 proteins were Deferentially Quantified Proteins (DQPs), based on 19,751 unique peptides. Of which 170 were depleted (decreased in abundance) and 69 were abundant in comparison of Bath Treated (BT) vs Control (C) groups. Similarly, 76 DQPs were depleted and 70 were abundant in comparison of Treated (T) vs BT groups. Further, 126 DQPs were depleted, and 34 were abundant in comparison to T vs C groups. The DQPs we report were mostly immunological and were involved in unique biological functions and pathways. The interesting protein we report, where some of the proteins are for the first time in fish, shows the protein-rich structure of the mucus of fish, which may act as a biomarker to be targeted for bacterial disease therapy in fish and ultimately hint to the way of making resistance in fish against bacterial pathogens.

Antibacterial activity and modes of action of a novel hepcidin isoform from the shrimp scad, Alepes djedaba (Forsskål, 1775)

Hepcidin, initially identified in human blood ultrafiltrate as cysteine rich Liver Expressed Antimicrobial Peptide (LEAP-1), is a core molecular conduit between iron trafficking and immune response. Though a great share of studies has been focused on the iron regulatory function of hepcidins, investigations on the antimicrobial aspects are relatively less. The present study is aimed at identification of hepcidin from a teleost fish, Alepes djedaba followed by its recombinant expression, testing antibacterial property, stability and evaluation of cytotoxicity. Modes of action on bacterial pathogens were also examined. A novel hepcidin isoform, Ad-Hep belonging to the HAMP1 (Hepcidin antimicrobial peptide 1) group of hepcidins was identified from the shrimp scad, Alepes djedaba. Ad-Hep with 2.9 kDa size was found to be a cysteine rich, cationic peptide (+4) with antiparallel beta sheet conformation, a furin cleavage site (RXXR) and 'ATCUN' motif. It was heterologously expressed in E. coli Rosettagami B(DE3)PLysS cells and the recombinant peptide, rAd-Hep was found to have significant antibacterial activity, especially against Edwardsiella tarda, Vibrio parahaemolyticus and Escherichia coli. Membrane depolarization followed by membrane permeabilization and Reactive Oxygen Species (ROS) production were found to be the modes of action of rAd-Hep on bacterial cells. Ad-Hep was found to be non-haemolytic to hRBC and non-cytotoxic in mammalian cell line. Stability of the peptide at varying temperature, pH and metal salts qualify them for applications in vivo. With significant bactericidal activity coupled with direct killing mechanisms, the rAd-Hep can be a promising drug candidate for therapeutic applications in medicine and fish culture systems.

From oncolytic peptides to oncolytic polymers: A new paradigm for oncotherapy

Traditional cancer therapy methods, especially those directed against specific intracellular targets or signaling pathways, are not powerful enough to overcome tumor heterogeneity and therapeutic resistance. Oncolytic peptides that can induce membrane lysis-mediated cancer cell death and subsequent anticancer immune responses, has provided a new paradigm for cancer therapy. However, the clinical application of oncolytic peptides is always limited by some factors such as unsatisfactory bio-distribution, poor stability, and off-target toxicity. To overcome these limitations, oncolytic polymers stand out as prospective therapeutic materials owing to their high stability, chemical versatility, and scalable production capacity, which has the potential to drive a revolution in cancer treatment. This review provides an overview of the mechanism and structure-activity relationship of oncolytic peptides. Then the oncolytic peptides-mediated combination therapy and the nano-delivery strategies for oncolytic peptides are summarized. Emphatically, the current research progress of oncolytic polymers has been highlighted. Lastly, the challenges and prospects in the development of oncolytic polymers are discussed.

Natural Anticancer Peptides from Marine Animal Species: Evidence from In Vitro Cell Model Systems

Anticancer peptides are short and structurally heterogeneous aminoacidic chains, which display selective cytotoxicity mostly against tumor cells, but not healthy cells, based on their different cell surface properties. Their anti-tumoral activity is carried out through interference with intracellular homeostasis, such as plasmalemma integrity, cell cycle control, enzymatic activities and mitochondrial functions, ultimately acting as angiogenesis-, drug resistance- and metastasis-inhibiting agents, immune stimulators, differentiation inducers and necrosis or extrinsic/intrinsic apoptosis promoters. The marine environment features an ever-growing level of biodiversity, and seas and oceans are poorly exploited mines in terms of natural products of biomedical interest. Adaptation processes to extreme and competitive environmental conditions led marine species to produce unique metabolites as a chemical strategy to allow inter-individual signalization and ensure survival against predators, infectious agents or UV radiation. These natural metabolites have found broad use in various applications in healthcare management, due to their anticancer, anti-angiogenic, anti-inflammatory and regeneration abilities. The aim of this review is to pick selected studies that report on the isolation of marine animal-derived peptides and the identification of their anticancer activity in in vitro cultures of cancer cells, and list them with respect to the taxonomical hierarchy of the source organism.

Tandem mass tag (TMT) quantitative proteomics and phosphoproteomic of Takifugu rubripes infected with Cryptocaryon irritans

In this study, we identified the differentially expressed proteins in gills stimulated by infected ciliates and analyzed the immune mechanisms of T. rubripes infected with the ciliate Cryptocaryon irritans. Through liquid chromatography analysis, a total of 144 proteins were identified with significant differences, of which 58 were upregulated and 86 were downregulated. Among phosphorylated proteins, we identified a total of 167 significantly different phosphorylated proteins, of which 44 were upregulated, 123 were downregulated, 60 were upregulated, and 208 were downregulated. We analyzed the data of proteomics and Phosphorylated proteome quantification protein omics to finally identify three phosphorylated proteins (RPS27, eNOS and CaM) and two phosphorylated protein kinases(CaMKII and MAPK1) as potential biomarkers for T. rubripes immune responses. We finally identified three phosphorylated proteins (RPS27, eNOS and CaM) and two phosphorylated protein kinases (CaMKII and MAPK1) as potential biomarkers of immune response of T. rubripes. Our research findings provide new insights into the immune mechanism of T. rubripes, which may serve as an effective indicator of C. irritans infection in T. rubripes.

In silico molecular and functional characterization of a dual function antimicrobial peptide, hepcidin (GIFT-Hep), isolated from genetically improved farmed tilapia (GIFT, Oreochromis niloticus)

BACKGROUND

Antimicrobial peptides (AMPs), innate immune response molecules in organisms, are also known for their dual functionality, exemplified by hepcidin-an immunomodulator and iron regulator. Identifying and studying various AMPs from fish species can provide valuable insights into the immune profiles of aquaculturally significant fish, which can be made use of in its culture.

RESULTS

Hepcidin, a dual-function antimicrobial peptide, was isolated from the gill tissue of Genetically Improved Farmed Tilapia (GIFT-Hep). GIFT-Hep consists of a 90 amino acid pre-propeptide with a 24-mer signal, a 40-mer propeptide, and a 26-mer mature peptide region. The mature peptide had a molecular weight of 3015.61 Da, a theoretical pI of 8.78, a net charge of +4.25, and a protein-binding potential of 2.06 kcal/mol. Four disulfide bonds were formed by eight cysteine residues in the mature region. The presence of positively charged arginine residues renders the peptide 50% hydrophobic. Molecular analysis of GIFT-Hep revealed the presence of a furin propeptide convertase motif, RX(K/R)R, which facilitates trimming of the peptide to yield the mature GIFT-Hep. The hypothetical iron regulatory sequence, QSHLSL, was also identified in the mature peptide. In silico predictions about the characteristics of GIFT-Hep, such as charge, hydrophobicity, high surface accessibility, transmembrane helical regions, hydrophobic faces, hot spots, and cell-penetrating properties, suggest that the peptide functions as an iron regulatory antimicrobial agent.

CONCLUSIONS

This study reports a hepcidin antimicrobial peptide with both HAMP1 and HAMP2 properties isolated from genetically improved farmed tilapia, and further evaluation of the properties will prove the feasibility of GIFT-Hep being used as a therapeutant in aquaculture.

In silico identification and in vitro assessment of a potential anti-breast cancer activity of antimicrobial peptide retrieved from the ATMP1 Anabas testudineus fish peptide

A previous study has shown that synthetic antimicrobial peptides (AMPs) derived from Anabas testudineus (ATMP1) could in-vitro inhibit the progression of breast cancer cell lines. In this study, we are interested in studying altered versions of previous synthetic AMPs to gain some insight into the peptides functions. The AMPs were altered and subjected to bioinformatics prediction using four databases (ADP3, CAMP-R3, AMPfun, and ANTICP) to select the highest anticancer activity. The bioinformatics in silico analysis led to the selection of two AMPs, which are ATMP5 (THPPTTTTTTTTTTTYTAAPATTT) and ATMP6 (THPPTTTTTTTTTTTTTAAPARTT). The in silico analysis predicted that ATMP5 and ATMP6 have anticancer activity and lead to cell death. The ATMP5 and ATMP6 were submitted to deep learning databases (ToxIBTL and ToxinPred2) to predict the toxicity of the peptides and to (AllerTOP & AllergenFP) check the allergenicity. The results of databases indicated that AMPs are non-toxic to normal human cells and allergic to human immunoglobulin. The bioinformatics findings led to select the highest active peptide ATMP5, which was synthesised and applied for in-vitro experiments using cytotoxicity assay MTT Assay, apoptosis detection using the Annexin V FTIC-A assay, and gene expression using Apoptosis PCR Array to evaluate the AMP's anticancer activity. The antimicrobial activity is approved by the disc diffusion method. The in-vitro experiments analysis showed that ATMP5 had the activity to inhibit the growth of the breast cancer cell line (MDA-MB-231) after 48 h and managed to arrest the cell cycle of the MDA-MB-231, apoptosis induction, and overexpression of the p53 by interaction with the related apoptotic genes. This research opened up new opportunities for developing potential and selective anticancer agents relying on antimicrobial peptide properties.

Current research status of anti-cancer peptides: Mechanism of action, production, and clinical applications

The escalating rate of cancer cases, together with treatment deficiencies and long-term side effects of currently used cancer drugs, has made this disease a global burden of the 21st century. The number of breast and lung cancer patients has sharply increased worldwide in the last few years. Presently, surgical treatment, radiotherapy, chemotherapy, and immunotherapy strategies are used to cure cancer, which cause severe side effects, toxicities, and drug resistance. In recent years, anti-cancer peptides have become an eminent therapeutic strategy for cancer treatment due to their high specificity and fewer side effects and toxicity. This review presents an updated overview of different anti-cancer peptides, their mechanisms of action and current production strategies employed for their manufacture. In addition, approved and under clinical trials anti-cancer peptides and their applications have been discussed. This review provides updated information on therapeutic anti-cancer peptides that hold great promise for cancer treatment in the near future.

Cbf-14, a cationic peptide derived from cathelin-domain, exhibits anti-inflammation activity via inhibiting PI3K- Akt /ROS/ NF-κB signaling pathway

Cbf-14 with the sequence RLLRKFFRKLKKSV, is an effective antimicrobial peptide derived from a cathelin-like domain. Previous reports have demonstrated that Cbf-14 not only exerts antimicrobial activity against penicillin-resistant bacteria but also alleviates bacterial-induced inflammation in E. coli BL21 (DE3)-NDM-1-infected mice. In this article, we demonstrated that Cbf-14 can effectively reduce RAW 264.7 intracellular infection caused by clinical strain E. coli and alleviate the inflammatory response of cells and improve cell survival after infection. Therefore, we established the LPS-stimulated RAW 264.7 cell inflammation model to uncover the molecular mechanisms of the peptide Cbf-14 in anti-inflammatory activity. The results reveal that Cbf-14 can decrease LPS-induced ROS secretion by blocking the membrane translocation of p47-phox subunits and suppressing p47-phox protein phosphorylation. Meanwhile, this peptide can down-regulate the over-expression of iNOS, and finally inhibit the NO excessive secretion from RAW 264.7 macrophages stimulated by LPS. Moreover, Cbf-14 also down-regulates the expression levels of p-IκB and p-p65 and inhibits the nuclear translocation of NF-κB through blocking MAPK- and/or PI3K-Akt signaling pathways. Overall, Cbf-14 exhibits anti-inflammatory activity through inhibiting NF-κB activity and ROS production via PI3K- Akt signaling pathway.

Antibacterial and immunoregulatory activity of an antimicrobial peptide hepcidin in loach (Misgurnus anguillicaudatus)

Antimicrobial peptides (AMPs) are members of humoral immunity and particpate in resisting microbial invasion. In this study, an AMP gene hepcidin was obtained from the oriental loach Misgurnus anguillicaudatus and named Ma-Hep. This Ma-Hep encodes a peptide of 90 amino acids, with a predicted active peptide segment (Ma-sHep) of 25 amino acids at C terminus. Stimulation by a bacterial pathogen Aeromonas hydrophila resulted in significant up-regulation of Ma-Hep transcripts in loach midgut, head kidney, and gill. Ma-Hep and Ma-sHep proteins were expressed in Pichia pastoris and their antibacterial activity was examined. Results showed that Ma-sHep possessed stronger antibacterial activity against various Gram-positive and Gram-negative bacteria, compared to Ma-Hep. Scanning electron microscopy showed that Ma-sHep might kill bacteria by destroying bacterial cell membranes. Moreover, we found that Ma-sHep had an inhibitory effect on blood cell apoptosis induced by A. hydrophila and facilitated the bacterial phagocytosis and clearance in loach. Histopathological analysis indicated Ma-sHep could protect liver and gut of loach from bacterial infection. Ma-sHep has high thermal stability and PH stability, which is conducive to further feed addition. Feed supplemented with Ma-sHep expressing yeast improved the intestinal flora of loach by increasing the dominant bacteria and decreasing the harmful bacteria. Feed supplemented with Ma-sHep expressing yeast also regulated the expression of inflammatory related factors in various tissues of loach and reduced the mortality of loach upon bacterial infection. These findings show that the antibacterial peptide Ma-sHep is involved in the antibacterial defense of loach and can be used as a candidate for new antimicrobial agents in aquaculture.

In silico analysis prediction of HepTH1-5 as a potential therapeutic agent by targeting tumour suppressor protein networks

Many studies reported that the activation of tumour suppressor protein, p53 induced the human hepcidin expression. However, its expression decreased when p53 was silenced in human hepatoma cells. Contrary to Tilapia hepcidin TH1-5, HepTH1-5 was previously reported to trigger the p53 activation through the molecular docking approach. The INhibitor of Growth (ING) family members are also shown to directly interact with p53 and promote cell cycle arrest, senescence, apoptosis and participate in DNA replication and DNA damage responses to suppress the tumour initiation and progression. However, the interrelation between INGs and HepTH1-5 remains unknown. Therefore, this study aims to identify the mechanism and their protein interactions using in silico approaches. The finding revealed that HepTH1-5 and its ligands had interacted mostly on hotspot residues of ING proteins which involved in histone modifications via acetylation, phosphorylation, and methylation. This proves that HepTH1-5 might implicate in an apoptosis signalling pathway and preserve the protein structure and function of INGs by reducing the perturbation of histone binding upon oxidative stress response. This study would provide theoretical guidance for the design and experimental studies to decipher the role of HepTH1-5 as a potential therapeutic agent for cancer therapy. Communicated by Ramaswamy H. Sarma.

Structural and functional characterisation of HepTH1-5 peptide as a potential hepcidin replacement

Hepcidin is a principal regulator of iron homeostasis and its dysregulation has been recognised as a causative factor in cancers and iron disorders. The strategy of manipulating the presence of hepcidin peptide has been used for cancer treatment. However, this has demonstrated poor efficiency and has been short-lived in patients. Many studies reported using minihepcidin therapy as an alternative way to treat hepcidin dysregulation, but this was only applied to non-cancer patients. Highly conserved fish hepcidin protein, HepTH1-5, was investigated to determine its potential use in developing a hepcidin replacement for human hepcidin (Hepc25) and as a therapeutic agent by targeting the tumour suppressor protein, p53, through structure-function analysis. The authors found that HepTH1-5 is stably bound to ferroportin, compared to Hepc25, by triggering the ferroportin internalisation via Lys42 and Lys270 ubiquitination, in a similar manner to the Hepc25 activity. Moreover, the residues Ile24 and Gly24, along with copper and zinc ligands, interacted with similar residues, Lys24 and Asp1 of Hepc25, respectively, showing that those molecules are crucial to the hepcidin replacement strategy. HepTH1-5 interacts with p53 and activates its function through phosphorylation. This finding shows that HepTH1-5 might be involved in the apoptosis signalling pathway upon a DNA damage response. This study will be very helpful for understanding the mechanism of the hepcidin replacement and providing insights into the HepTH1-5 peptide as a new target for hepcidin and cancer therapeutics.Communicated by Ramaswamy H. Sarma.

Mesenchymal Stem Cell-Derived Antimicrobial Peptides as Potential Anti-Neoplastic Agents: New Insight into Anticancer Mechanisms of Stem Cells and Exosomes

Mesenchymal stem cells (MSCs), as adult multipotent cells, possess considerable regenerative and anti-neoplastic effects, from inducing apoptosis in the cancer cells to reducing multidrug resistance that bring them up as an appropriate alternative for cancer treatment. These cells can alter the behavior of cancer cells, the condition of the tumor microenvironment, and the activity of immune cells that result in tumor regression. It has been observed that during inflammatory conditions, a well-known feature of the tumor microenvironment, the MSCs produce and release some molecules called “antimicrobial peptides (AMPs)” with demonstrated anti-neoplastic effects. These peptides have remarkable targeted anticancer effects by attaching to the negatively charged membrane of neoplastic cells, disrupting the membrane, and interfering with intracellular pathways. Therefore, AMPs could be considered as a part of the wide-ranging anti-neoplastic effects of MSCs. This review focuses on the possible anti-neoplastic effects of MSCs-derived AMPs and their mechanisms. It also discusses preconditioning approaches and using exosomes to enhance AMP production and delivery from MSCs to cancer cells. Besides, the clinical administration of MSCs-derived AMPs, along with their challenges in clinical practice, were debated.

The impact of bioactive compounds derived from marine fish on cancer

Cancer persists as the world's leading cause of mortality, thereby making it a compelling condition to research and potentially develop prevention options. Anticancer therapies such as chemotherapy, surgery and radiation therapy are becoming highly futile and tend to have achieved a clinical deficit, due to massive side effects, toxicities, and limited specificity. Anticancer agents from natural sources, such as aquatic fishes, terrestrial mammals, animal venoms, and amphibians, have mainly been focused on in recent researches. Edible marine fishes contain high contents of fatty acids, vitamins, and proteins, also having bioactive compounds. Fish derivatives are naturally having the potential to target cancer cells while being less hazardous to normal tissues, making them a better choice for cancer prevention and therapy. In this review, we mainly focused on the bioactive compounds identified from marine fishes which have significant biological properties including anticancer effects, also discuss the mechanism of action.

A hepatic antimicrobial peptide, hepcidin from Indian major carp, Catla catla: molecular identification and functional characterization

Background

Increase of antibiotic resistance in pathogenic microbes necessitated novel molecules for curing infection. Antimicrobial peptides (AMPs) are the gene-encoded evolutionarily conserved small molecules with therapeutic value. AMPs are considered as an alternative drug for conventional antibiotics. Hepcidin, the cysteine-rich antimicrobial peptide, is an important component in innate immune response. In this study, we identified and characterized hepcidin gene from the fish, Catla catla (Indian major carp) and termed it as Cc-Hep.

Results

Open reading frame of Cc-Hep consists of 261 base pair that encodes 87 amino acids. Cc-Hep is synthesized as a prepropeptide consisting of 24 amino acid signal peptide, 36 amino acid propeptide, and 26 amino acid mature peptide. Sequence analysis revealed that Cc-Hep shared sequence similarity with hepcidin from Sorsogona tuberculata. Phylogenetic analysis indicated that Cc-Hep was grouped with HAMP2 family. Structure analysis of mature Cc-Hep identified two antiparallel beta sheets stabilized by four disulphide bonds and a random coil. The mature peptide region of Cc-Hep has a charge of + 2, isoelectric value 8.23 and molecular weight 2.73 kDa.

Conclusion

Functional characterization predicted antibacterial, antioxidant, and anticancer potential of Cc-Hep, which can be explored in aquaculture or human health care.

Exploring Marine as a Rich Source of Bioactive Peptides: Challenges and Opportunities from Marine Pharmacology

This review highlights the underexplored potential and promises of marine bioactive peptides (MBPs) with unique structural, physicochemical, and biological activities to fight against the current and future human pathologies. A particular focus is given to the marine environment as a significant source to obtain or extract high-value MBPs from touched/untouched sources. For instance, marine microorganisms, including microalgae, bacteria, fungi, and marine polysaccharides, are considered prolific sources of amino acids at large, and peptides/polypeptides in particular, with fundamental structural sequence and functional entities of a carboxyl group, amine, hydrogen, and a variety of R groups. Thus, MBPs with tunable features, both structural and functional entities, along with bioactive traits of clinical and therapeutic value, are of ultimate interest to reinforce biomedical settings in the 21st century. On the other front, as the largest biome globally, the marine biome is the so-called "epitome of untouched or underexploited natural resources" and a considerable source with significant potentialities. Therefore, considering their biological and biomedical importance, researchers around the globe are redirecting and/or regaining their interests in valorizing the marine biome-based MBPs. This review focuses on the widespread bioactivities of MBPs, FDA-approved MBPs in the market, sustainable development goals (SDGs), and legislation to valorize marine biome to underlying the impact role of bioactive elements with the related pathways. Finally, a detailed overview of current challenges, conclusions, and future perspectives is also given to satisfy the stimulating demands of the pharmaceutical sector of the modern world.

Expression of the Antimicrobial Peptide Piscidin 1 and Neuropeptides in Fish Gill and Skin: A Potential Participation in Neuro-Immune Interaction

Antimicrobial peptides (AMPs) are found widespread in nature and possess antimicrobial and immunomodulatory activities. Due to their multifunctional properties, these peptides are a focus of growing body of interest and have been characterized in several fish species. Due to their similarities in amino-acid composition and amphipathic design, it has been suggested that neuropeptides may be directly involved in the innate immune response against pathogen intruders. In this review, we report the molecular characterization of the fish-specific AMP piscidin1, the production of an antibody raised against this peptide and the immunohistochemical identification of this peptide and enkephalins in the neuroepithelial cells (NECs) in the gill of several teleost fish species living in different habitats. In spite of the abundant literature on Piscidin1, the biological role of this peptide in fish visceral organs remains poorly explored, as well as the role of the neuropeptides in neuroimmune interaction in fish. The NECs, by their role as sensors of hypoxia changes in the external environments, in combination with their endocrine nature and secretion of immunomodulatory substances would influence various types of immune cells that contain piscidin, such as mast cells and eosinophils, both showing interaction with the nervous system. The discovery of piscidins in the gill and skin, their diversity and their role in the regulation of immune response will lead to better selection of these immunomodulatory molecules as drug targets to retain antimicrobial barrier function and for aquaculture therapy in the future.

Natural Peptides Inducing Cancer Cell Death: Mechanisms and Properties of Specific Candidates for Cancer Therapeutics

Nowadays, cancer has become the second highest leading cause of death, and it is expected to continue to affect the population in forthcoming years. Additionally, treatment options will become less accessible to the public as cases continue to grow and disease mechanisms expand. Hence, specific candidates with confirmed anticancer effects are required to develop new drugs. Among the novel therapeutic options, proteins are considered a relevant source, given that they have bioactive peptides encrypted within their sequences. These bioactive peptides, which are molecules consisting of 2–50 amino acids, have specific activities when administered, producing anticancer effects. Current databases report the effects of peptides. However, uncertainty is found when their molecular mechanisms are investigated. Furthermore, analyses addressing their interaction networks or their directly implicated mechanisms are needed to elucidate their effects on cancer cells entirely. Therefore, relevant peptides considered as candidates for cancer therapeutics with specific sequences and known anticancer mechanisms were accurately reviewed. Likewise, those features which turn certain peptides into candidates and the mechanisms by which peptides mediate tumor cell death were highlighted. This information will make robust the knowledge of these candidate peptides with recognized mechanisms and enhance their non-toxic capacity in relation to healthy cells and further avoid cell resistance.

Natural Peptides Inducing Cancer Cell Death: Mechanisms and Properties of Specific Candidates for Cancer Therapeutics

Nowadays, cancer has become the second highest leading cause of death, and it is expected to continue to affect the population in forthcoming years. Additionally, treatment options will become less accessible to the public as cases continue to grow and disease mechanisms expand. Hence, specific candidates with confirmed anticancer effects are required to develop new drugs. Among the novel therapeutic options, proteins are considered a relevant source, given that they have bioactive peptides encrypted within their sequences. These bioactive peptides, which are molecules consisting of 2–50 amino acids, have specific activities when administered, producing anticancer effects. Current databases report the effects of peptides. However, uncertainty is found when their molecular mechanisms are investigated. Furthermore, analyses addressing their interaction networks or their directly implicated mechanisms are needed to elucidate their effects on cancer cells entirely. Therefore, relevant peptides considered as candidates for cancer therapeutics with specific sequences and known anticancer mechanisms were accurately reviewed. Likewise, those features which turn certain peptides into candidates and the mechanisms by which peptides mediate tumor cell death were highlighted. This information will make robust the knowledge of these candidate peptides with recognized mechanisms and enhance their non-toxic capacity in relation to healthy cells and further avoid cell resistance.

Anti-breast cancer synthetic peptides derived from the Anabas testudineus skin mucus fractions

Previous study has shown the antimicrobial activities of mucus protein extracted from Anabastestudineus. In this study, we are interested in characterizing the anticancer activity of the A.testudineus antimicrobial peptides (AMPs). The mucus was extracted, fractioned, and subjected to antibacterial activity testing to confirm the fish's AMPs production. The cytotoxic activity of each fraction was also identified. Fraction 2 (F2), which shows toxicity against MCF7 and MDA-MB-231 were sent for peptide sequencing to identify the bioactive peptide. The two peptides were then synthetically produced and subjected to cytotoxic assay to prove their efficacy against cancer cell lines. The IC₅₀ for AtMP1 against MCF7 and MDA-MB-231 were 8.25 ± 0.14 μg/ml and 9.35 ± 0.25 μg/ml respectively, while for AtMP2 it is 5.89 ± 0.14 μg/ml and 6.97 ± 0.24 μg/ml respectively. AtMP1 and AtMP2 treatment for 48 h induced breast cancer cell cycle arrest and apoptosis by upregulating the p53, which lead to upregulate pro-apoptotic BAX gene and downregulate the anti-apoptotic BCL-2 gene, consequently, trigger the activation of the caspase-3. This interaction was supported by docking analysis (QuickDBD, HPEPDOCK, and ZDOCK) and immunoprecipitation. This study provided new prospects in the development of highly effective and selective cancer therapeutics based on antimicrobial peptides.

The Era of Antimicrobial Peptides: Use of Hepcidins to Prevent or Treat Bacterial Infections and Iron Disorders

The current treatments applied in aquaculture to limit disease dissemination are mostly based on the use of antibiotics, either as prophylactic or therapeutic agents, with vaccines being available for a limited number of fish species and pathogens. Antimicrobial peptides are considered as promising novel substances to be used in aquaculture, due to their antimicrobial and immunomodulatory activities. Hepcidin, the major iron metabolism regulator, is found as a single gene in most mammals, but in certain fish species, including the European sea bass (Dicentrarchus labrax), two different hepcidin types are found, with specialized roles: the single type 1 hepcidin is involved in iron homeostasis trough the regulation of ferroportin, the only known iron exporter; and the various type 2 hepcidins present antimicrobial activity against a number of different pathogens. In this study, we tested the administration of sea bass derived hepcidins in models of infection and iron overload. Administration with hamp2 substantially reduced fish mortalities and bacterial loads, presenting itself as a viable alternative to the use of antibiotics. On the other hand, hamp1 seems to attenuate the effects of iron overload. Further studies are necessary to test the potential protective effects of hamp2 against other pathogens, as well as to understand how hamp2 stimulate the inflammatory responses, leading to an increased fish survival upon infection.

Hepcidin Downregulation Correlates With Disease Aggressiveness And Immune Infiltration in Liver Cancers

Background

Hepcidin is a polypeptide hormone mainly produced by hepatocytes to modulate systemic iron balance. A drastic downregulation of the hepcidin gene was found in liver cancers. However, there is a paucity of information about the clinical significance of hepcidin gene downregulation in liver cancers.

Methods

Hepcidin expression profiles were assessed using multiple public datasets via several bioinformatics platforms. Clinical and pathological information was utilized to stratify patients for comparison. Patient survival outcomes were evaluated using the Kaplan-Meier plotter, a meta-analysis tool. Tumor immune infiltration was analyzed using the single sample gene set enrichment analysis (ssGSEA) approach on the Cancer Genome Atlas (TCGA) dataset. Hepcidin antagonist Fursultiamine was used to treat liver cancer HepG2 and Huh7 cells together with Sorafenib.

Results

Hepcidin gene was predominantly expressed in benign liver tissues but drastically decreased in liver cancer tissues. Hepcidin reduction in liver cancers correlated with risk factors like non-alcoholic fatty liver disease (NAFLD) and liver fibrosis, as well as cancer grade and tumor stage. Hepcidin downregulation was associated with a rapid cancer progression and worse disease-specific survival, especially in patients of the White race without alcohol consumption history. Hepcidin expression in liver cancer tissues positively correlated with the bone morphogenetic protein-6 (BPM6)/interleukin-6 (IL6) cytokines and cytotoxic immune infiltration. Blocking hepcidin action with its antagonist Fursultiamine moderately reduced Sorafenib-induced apoptotic cell death in HepG2 and Huh7 cells.

Conclusion

Hepcidin downregulation in liver cancers correlated with liver cancer risk factors, cancer aggressiveness, cytotoxic immune cell infiltration, and patient survival outcomes. BMP6/IL6 pathway insufficiency is a potential cause of hepcidin downregulation in liver cancers.

Copper-binding anticancer peptides from the piscidin family: an expanded mechanism that encompasses physical and chemical bilayer disruption

In the search for novel broad-spectrum therapeutics to fight chronic infections, inflammation, and cancer, host defense peptides (HDPs) have garnered increasing interest. Characterizing their biologically-active conformations and minimum motifs for function represents a requisite step to developing them into efficacious and safe therapeutics. Here, we demonstrate that metallating HDPs with Cu2+ is an effective chemical strategy to improve their cytotoxicity on cancer cells. Mechanistically, we find that prepared as Cu2+-complexes, the peptides not only physically but also chemically damage lipid membranes. Our testing ground features piscidins 1 and 3 (P1/3), two amphipathic, histidine-rich, membrane-interacting, and cell-penetrating HDPs that are α-helical bound to membranes. To investigate their membrane location, permeabilization effects, and lipid-oxidation capability, we employ neutron reflectometry, impedance spectroscopy, neutron diffraction, and UV spectroscopy. While P1-apo is more potent than P3-apo, metallation boosts their cytotoxicities by up to two- and seven-fold, respectively. Remarkably, P3-Cu2+ is particularly effective at inserting in bilayers, causing water crevices in the hydrocarbon region and placing Cu2+ near the double bonds of the acyl chains, as needed to oxidize them. This study points at a new paradigm where complexing HDPs with Cu2+ to expand their mechanistic reach could be explored to design more potent peptide-based anticancer therapeutics.

Antimicrobial Peptides and Copper(II) Ions: Novel Therapeutic Opportunities

The emergence of new pathogens and multidrug resistant bacteria is an important public health issue that requires the development of novel classes of antibiotics. Antimicrobial peptides (AMPs) are a promising platform with great potential for the identification of new lead compounds that can combat the aforementioned pathogens due to their broad-spectrum antimicrobial activity and relatively low rate of resistance emergence. AMPs of multicellular organisms made their debut four decades ago thanks to ingenious researchers who asked simple questions about the resistance to bacterial infections of insects. Questions such as "Do fruit flies ever get sick?", combined with pioneering studies, have led to an understanding of AMPs as universal weapons of the immune system. This review focuses on a subclass of AMPs that feature a metal binding motif known as the amino terminal copper and nickel (ATCUN) motif. One of the metal-based strategies of hosts facing a pathogen, it includes wielding the inherent toxicity of copper and deliberately trafficking this metal ion into sites of infection. The sudden increase in the concentration of copper ions in the presence of ATCUN-containing AMPs (ATCUN-AMPs) likely results in a synergistic interaction. Herein, we examine common structural features in ATCUN-AMPs that exist across species, and we highlight unique features that deserve additional attention. We also present the current state of knowledge about the molecular mechanisms behind their antimicrobial activity and the methods available to study this promising class of AMPs.

Targeting Cancer Heterogeneity with Immune Responses Driven by Oncolytic Peptides

Accumulating preclinical and clinical evidence indicates that high degrees of heterogeneity among malignant cells constitute a considerable obstacle to the success of cancer therapy. This calls for the development of approaches that operate - or enable established treatments to operate - despite such intratumoral heterogeneity (ITH). In this context, oncolytic peptides stand out as promising therapeutic tools based on their ability to drive immunogenic cell death associated with robust anticancer immune responses independently of ITH. We review the main molecular and immunological pathways engaged by oncolytic peptides, and discuss potential approaches to combine these agents with modern immunotherapeutics in support of superior tumor-targeting immunity and efficacy in patients with cancer.

Evaluation of fish skin as a biological dressing for metacarpal wounds in donkeys

Background

The use of biological dressings has recently emerged in the management of burns and wounds. The aim of the present study was to evaluate the Nile tilapia skin as a biological dressing for full-thickness cutaneous metacarpal wounds in donkeys. The study was conducted on nine clinically healthy donkeys (n = 9). Here, fish skin dressings were obtained from fresh Nile tilapia (Oreochromis niloticus and sterilized by immersion in silver nanoparticles (AgNPs) solution for 5 min, with no change in collagen content. Bilateral, circular full-thickness excisional skin wounds (2 cm in diameter) were created on the dorsal aspect of the mid-metacarpals of each donkey. Wounds on the right metacarpals (treated wounds, n = 9) were dressed with sterile fish skins, while wounds on the left metacarpals (control wounds, n = 9) were dressed with sterile non-adherent dressing pads without any topical applications. Wound dressings were changed weekly. Wounds were evaluated microbiologically, grossly, and histologically on days 7, 14, and 21 post-wound inductions.

Results

Fish skin-dressed wounds showed a significant (P < 0.0001) reduction in microbial counts (Total viable bacterial count, Staphylococcal count, and Coliform count), a significant (P < 0.0001) decrease in the wound size, and a significant reduction (P < 0.0001) in the epithelial gap compared to the untreated wounds. No frequent dressing changes were needed.

Conclusions

Fish skin dressing accelerated the wound healing process and efficiently inhibited the local microbial activity and exuberant granulation tissue formation suggesting its reliable and promising application for metacarpal wounds of donkeys.

Immunomodulatory function of antimicrobial peptide EC-Hepcidin1 modulates the induction of inflammatory gene expression in primary cells of Caspian Trout (Salmo trutta caspius Kessler, 1877)

Hepcidins, a group of antimicrobial peptides (AMPs), play a key role in the innate immune system of fishes and act against different pathogens. In this study, antimicrobial and immune-inflammatory activity of a synthetic EC-hepcidin1, previously identified from orange-spotted grouper, were evaluated. EC-hepcidin1 showed weak activity against the zoonotic fish pathogen Streptococcus iniae (MIC 100 μg mL^-1 and MBC 150 μg mL^-1). To study the effect of AMPs in general, and EC-hepcidin1 in particular, a primary cell culture (SC) from the fin tissue of the Caspian Trout (Salmo trutta caspius) was established. The neutral Red method on SC cells revealed that EC-hepcidin1 has no or very low cytotoxic properties. Treatment of cells with either EC-hepcidin1 (150 μg mL^-1) or fish pathogen Streptococcus iniae (MOI = 10) and a mixture of both resulted in the up-regulation of gene expression of MHC-UBA, IL-6, and TNFα indicating the modulatory function on inflammatory processes. These findings indicate that EC-hepcidin1 might act as a candidate for modulation of the innate immune system in S. iniae-based infection.

Anticancer potential of human intestinal defensin 5 against 1, 2-dimethylhydrazine dihydrochloride induced colon cancer: A therapeutic approach

The escalating predicament of multidrug resistant cancer cells and associated side effects of conventional chemotherapy necessitates the exploration of alternative anticancer therapies. The present study evaluated anticancer therapeutic potential of human defensin 5 (HD-5) against colon cancer. The in vivo anticancer efficacy of HD-5 against 1,2-dimethylhydrazine (DMH) induced colon cancer was elucidated in terms of tumor biostatistics, number of aberrant crypt foci (ACF), in situ apoptosis assay,changes in morphological as well as histological architecture of colon(s). The direct interaction of peptide was investigated by incubating peptide with normal and/or cancerous colonocytes followed by phase contrast, Hoechst 3342 and AO/PI staining as well as confocal microscopy. Changes in membrane dynamics were evaluated by MC 540 and N-NBD-PE staining. In vivo decrease(s) in tumor parameters, number of aberrant crypt foci along with marked increase in the rate of apoptosis was observed.H&E staining revealed neutrophils infiltration and restoration of normal architecture in treated colon(s) which was consistent with scanning electron microscopic observations. Furthermore, non-membranolytic mechanism was found to be acquired by peptide as it could traverse cell membrane gaining access to nucleus and cytoplasm thereby disintegrating cellular architecture. MC 540 and NBD-PE staining revealed that peptide could bind to cancerous cells by taking advantage of altered fluidity levels. Our results indicated that HD-5 exhibited strong cancer cell killing and does not affect normal host cells. The peptide can be exploited as promising option to combat developing menace of colon cancer and/or can at least be used as an adjunct to present day chemotherapies.

Administration of dietary recombinant hepcidin on grass carp (Ctenopharyngodon idella) against Flavobacterium columnare infection under cage aquaculture conditions

Hepcidin links iron metabolism with innate immunity during the inhibition of bacterial infection. Our previous studies had shown that recombinant hepcidin can significantly reduce the mortality rate of Ctenopharyngodon idella infected with Flavobacterium columnare under laboratory conditions. Here, we studied the preventive and therapeutic effects of feed supplemented with different doses of recombinant hepcidin on F. columnare-challenged C. idella reared in a cage culture environment. The results showed that in the prevention groups, 30 and 90 mg/kg of added purified and unpurified hepcidin respectively resulted in a higher survival rate in the early post-infection period, while 60 mg/kg of purified hepcidin significantly improved the survival rate in the therapy group (all compared to the control group). In the hepatopancreas, the expression of hepcidin and ferritin was significantly up-regulated, and the levels of ferroportin and serum iron were significantly decreased, especially in the therapy group. In addition, the expression of iron-related genes in spleen and intestine exhibited a similar trend to that in hepatopancreas. Meanwhile, immune genes were up-regulated to varying degrees, and the therapy group exhibited a significantly improved expression of pro-inflammatory cytokines and specific immunity. In summary, our study shows that different doses of recombinant hepcidin had protective effects against bacterial infection by regulating the iron distribution and immune gene expression, which provides a strong foundation for the application of recombinant hepcidin in aquaculture.

Antibacterial and immunoregulatory activity of a novel hepcidin homologue in diploid hybrid fish (Carassius auratus cuvieri ♀ × Carassius auratus red var ♂)

Hepcidin, a multifunctional hormone oligopeptide, not only exhibits a regulatory role in iron metabolism, but also participates in the regulation of teleostean immunity. In this study, ORF sequence of WR-hepcidin was 258 bp and encoded 85 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-hepcidin was observed in liver. Aeromonas hydrophila challenge can sharply increased WR-hepcidin mRNA expression in liver, trunk kidney and spleen. The purified WR-hepcidin fusion peptide can directly bind to A. hydrophila and Streptococcus agalactiae, reduce the relative bacterial activity, limit bacterial growth and attenuate their dissemination to tissues in vivo. In addition, the treatment of WR-hepcidin fusion protein can diminish the production of pro-inflammatory cytokines. These results indicated that WR-hepcidin can play a negative regulatory role in bacteria-stimulated pro-inflammatory cytokines production and MyD88-IRAK4 activation.

Teleost antimicrobial peptide hepcidin contributes to host defense of goldfish (Carassius auratus L.) against Trypanosoma carassii

Hepcidin is an antimicrobial peptide and an iron regulatory protein that prevents the release of excess iron in the blood. There is evidence suggesting that teleost hepcidin is a major player in antimicrobial defense against various bacteria species, but little is known regarding the effects of teleost hepcidin in protozoan parasitic infections. We examined the role of hepcidin during the course of infection of goldfish with Trypanosoma carassii. Quantitative real-time PCR was used to determine the expression of hepcidin in goldfish immune organs during the course of T. carassii infection. During the acute phase of the T. carassii infection, the mRNA levels of hepcidin were up-regulated in liver and kidney. In contrast, an up-regulation of hepcidin mRNA expression in spleen was observed during the chronic phase of the infection. Furthermore, a synthetic goldfish hepcidin peptide induced trypanosome lysis in vitro, and parasite surface disruption was confirmed by scanning electron microscopy (SEM) analysis. These results suggest that, in addition to well-characterized direct antibacterial activities, teleost hepcidin also exhibits trypanocidal activity.

Use of Tilapia Hepcidin in Oral Cancer Therapeutics: A Proposal

Tilapia hepcidin (TH), an antimicrobial peptide (AMP) derived from tilapia (Oreochromis mossambicus) forms an important component of the fish innate immune defense.1 However, the functionality of TH is not just limited to its antimicrobial actions, significant applications in cancer research remain an area to be explored. Antimicrobial peptides derived from fish and shrimp demonstrated anticancer activities in addition to their previously discovered antimicrobial action. Three hepcidin-like AMPs can be isolated from tilapia, namely TH1-5, TH2-2, and TH2-3. Of these, TH1-5 and TH2-3 have shown potent antitumor activity.2.

An in vitro and in silico study on the antioxidant and cell culture-based study on the chemoprotective activities of fish muscle protein hydrolysates obtained from European seabass and gilthead seabream

European seabass (Dicentrarchus labrax, Linnaeus, 1758) (L) and gilthead seabream (Sparus aurata, Linnaeus, 1758) (C) muscles were hydrolysated by Alcalase (L_alc, C_alc) and Chymotrypsin (L_ch, C_ch) then hydrolysates were examined and their peptide profiles obtained. A total of 765, 794, 132 and 232 peptides were identified in C_alc, L_alc, C_ch and L_ch, respectively. Although, L_ch and C_ch were expected to have more antioxidant capacity because of their peptide profiles, Alcalase hydrolysates observed in vitro, were slightly higher (TEAC assay for C_alc: 848.11 ± 60.78 μmol TE/g protein). Maximum inhibition of oxidative stress was determined for L_alc (12.8% ± 4.5%) in MDCK1 cell lines. Highest proliferative capacity observed for C_alc (147.0% ± 3.1%) at MTT assay in MDCK1 cell culture. L_ch showed the highest chemopreventive effect with a 40-60% decrease for human colon adenocarcinoma cell line HT-29. This research points out the importance of aquatic sources as raw materials for peptide researches.

Teleosts Genomics: Progress and Prospects in Disease Prevention and Control

Genome wide studies based on conventional molecular tools and upcoming omics technologies are beginning to gain functional applications in the control and prevention of diseases in teleosts fish. Herein, we provide insights into current progress and prospects in the use genomics studies for the control and prevention of fish diseases. Metagenomics has emerged to be an important tool used to identify emerging infectious diseases for the timely design of rational disease control strategies, determining microbial compositions in different aquatic environments used for fish farming and the use of host microbiota to monitor the health status of fish. Expounding the use of antimicrobial peptides (AMPs) as therapeutic agents against different pathogens as well as elucidating their role in tissue regeneration is another vital aspect of genomics studies that had taken precedent in recent years. In vaccine development, prospects made include the identification of highly immunogenic proteins for use in recombinant vaccine designs as well as identifying gene signatures that correlate with protective immunity for use as benchmarks in optimizing vaccine efficacy. Progress in quantitative trait loci (QTL) mapping is beginning to yield considerable success in identifying resistant traits against some of the highly infectious diseases that have previously ravaged the aquaculture industry. Altogether, the synopsis put forth shows that genomics studies are beginning to yield positive contribution in the prevention and control of fish diseases in aquaculture.

Targeting FOSB with a cationic antimicrobial peptide, TP4, for treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) currently lacks a suitable therapeutic candidate and is thus difficult to treat. Here, we report that a cationic antimicrobial peptide (CAP), tilapia piscidin 4 (TP4), which was derived from Nile tilapia (Oreochromis niloticus), is selectively toxic to TNBC. TP4 acts by inducing an AP-1 protein called FOSB, the expression of which is negatively associated with the pathological grade of TNBC. We show that TP4 is bound to the mitochondria where it disrupts calcium homeostasis and activates FOSB. FOSB overexpression results in TNBC cell death, whereas inhibition of calcium signaling eliminates FOSB induction and blocks TP4-induced TNBC cell death. Both TP4 and anthracyclines strongly induced FOSB, particularly in TNBC, indicating that FOSB may be suitable as a biomarker of drug responses. This study thus provides a novel therapeutic approach toward TNBC through FOSB induction.

MSP-4, an Antimicrobial Peptide, Induces Apoptosis via Activation of Extrinsic Fas/FasL- and Intrinsic Mitochondria-Mediated Pathways in One Osteosarcoma Cell Line

Osteosarcoma (OS) is a common malignant bone cancer. The relatively high density of a person's bone structure means low permeability for drugs, and so finding drugs that can be more effective is important and should not be delayed. MSPs are marine antimicrobial peptides (AMP) and natural compounds extracted from Nile tilapia (Oreochromis niloticus). MSP-4 is a part of the AMPs series, with the advantage of having a molecular weight of about 2.7-kDa and anticancer effects, although the responsible anticancer mechanism is not very clear. The goal of this study is to determine the workings of the mechanism associated with apoptosis resulting from MSP-4 in osteosarcoma MG63 cells. The study showed that MSP-4 significantly induced apoptosis in MG63 cells, with Western blot indicating that MSP-4 induced this apoptosis through an intrinsic pathway and an extrinsic pathway. Thus, a pretreatment system with a particular inhibitor of Z-IETD-FMK (caspase-8 inhibitor) and Z-LEHD-FMK (caspase-9 inhibitor) significantly attenuated the cleavage of caspase-3 and prevented apoptosis. These observations indicate that low concentrations of MSP-4 can help induce the apoptosis of MG63 through a Fas/FasL- and mitochondria-mediated pathway and suggest a potentially innovative alternative to the treatment of human osteosarcoma.

Antimicrobial Peptides As Biologic and Immunotherapeutic Agents against Cancer: A Comprehensive Overview

Antimicrobial peptides (AMPs) are a pervasive and evolutionarily ancient component of innate host defense which is present in virtually all classes of life. In recent years, evidence has accumulated that parallel or de novo mechanisms by which AMPs curb infectious pathologies are also effective at restraining cancer cell proliferation and dissemination, and have consequently stimulated significant interest in their deployment as novel biologic and immunotherapeutic agents against human malignancies. In this review, we explicate the biochemical underpinnings of their tumor-selectivity, and discuss results of recent clinical trials (outside of oncologic indications) which substantiate their safety and tolerability profiles. Next, we present evidence for their preclinical antitumor activity, systematically organized by the major and minor classes of natural AMPs. Finally, we discuss the barriers to their clinical implementation and envision directions for further development.

Ontogeny and modulation after PAMPs stimulation of β-defensin, hepcidin, and piscidin antimicrobial peptides in meagre (Argyrosomus regius)

Antimicrobial peptides (AMPs), components of innate immunity, play an important role in protecting fish. In this study we report the molecular cloning of full open reading frames and characterization of expression of three AMP genes (β-defensin (defb), hepcidin (hep2), piscidin (pisc) in meagre (Argyrosomus regius). A phylogenetic analysis of the expressed sequences obtained shows the defensin isoform forms a clade with the other members of the beta class of this family, hepcidin corresponds to hepcidin 2, and piscidin corresponds to class I of its respective family. Gene expression profiles of AMPs was investigated, by means of quantification of mRNA in nine development stages, from 8 days post-hatching (dph) to accomplishment of juvenile form (120 dph). During development it was demonstrated defb, hep2, pisc were expressed in all stages of larval development and in juvenile tissues (kidney, spleen gut and gill). Moreover, expression patterns suggest the expression levels of theses AMPs are influenced by live prey (rotifer, Artemia) and first intake of commercial diet. Induction experiments in vivo (24 h) and in vitro (4, 12, 24 h) with PAMPs (LPS, poly (I:C), β-glucan) revealed significant changes in gene expression of the three AMP genes, in kidney, spleen, gut and gill. However, expression profiles differed in magnitude and time course response. defb expression shows a similar trend in vivo and in vitro in kidney at 24 h after LPS and β-glucan stimulation. The hep2 expression levels were up-regulated upon β-glucan challenge in vivo, more in gut and gills than kidney, while in vitro hep2 expression was up-regulated in kidney cells by LPS, poly (I:C), β-glucan (4 h). pisc expression was up-regulated in kidney cells, splenocytes by β-glucan, but in gill cells by poly (I:C) and β-glucan in vivo. However, pisc expression was upregulated in kidney cells by β-glucan and gill cells by LPS at 4 post-stimulation in vitro. These data suggest that AMPs play an important role in defense against pathogens, with each AMP having differing efficacies against specific types of microorganisms, although follow-up studies focusing on the biological activities in fish are needed.

Tumor cell membrane-targeting cationic antimicrobial peptides: novel insights into mechanisms of action and therapeutic prospects

There is an ongoing need for effective and targeted cancer treatments that can overcome the detrimental side effects presented by current treatment options. One class of novel anticancer molecules with therapeutic potential currently under investigation are cationic antimicrobial peptides (CAPs). CAPs are small innate immunity peptides found ubiquitously throughout nature that are typically membrane-active against a wide range of pathogenic microbes. A number of CAPs can also target mammalian cells and often display selective activity towards tumor cells, making them attractive candidates as novel anticancer agents warranting further investigation. This current and comprehensive review describes key examples of naturally occurring membrane-targeting CAPs and their modified derivatives that have demonstrated anticancer activity, across multiple species of origin and structural subfamilies. In addition, we address recent advances made in the field and the ongoing challenges faced in translating experimental findings into clinically relevant treatments.

Anticancer potential of bioactive peptides from animal sources (Review)

Cancer is the most common cause of human death worldwide. Conventional anticancer therapies, including chemotherapy and radiation, are associated with severe side effects and toxicities as well as low specificity. Peptides are rapidly being developed as potential anticancer agents that specifically target cancer cells and are less toxic to normal tissues, thus making them a better alternative for the prevention and management of cancer. Recent research has focused on anticancer peptides from natural animal sources, such as terrestrial mammals, marine animals, amphibians, and animal venoms. However, the mode of action by which bioactive peptides inhibit the proliferation of cancer cells remains unclear. In this review, we present the animal sources from which bioactive peptides with anticancer activity are derived and discuss multiple proposed mechanisms by which these peptides exert cytotoxic effects against cancer cells.

Expression of ayu antimicrobial peptide genes after LPS stimulation

Plecoglossus altivelis (ayu) is one of the most important fish species in the Japanese islands and in internal fish hatcheries. Living in open aquatic environments exposes fish to many pathogens. Therefore, they require rapid and strong immune defenses. We investigated in vivo the direct association between the ayu innate immune response, represented by the relative transcription of genes encoding the cathelicidin and hepcidin antimicrobial peptides, and lipopolysaccharide (LPS), a conventional pathogen-associated molecular patterns (PAMPs) of Gram-negative bacteria. Different concentrations of LPS (1, 10 and 100 µg/fish) were injected intraperitoneally into young (sexually immature) and adult (fully sexually mature) ayu. The relative expression of the antimicrobial peptide genes was measured 6 hr, 24 hr and 1 week after stimulation with LPS. We found a direct association between the expression of the antimicrobial peptide genes investigated and LPS stimulation. This relationship was time-, dose- and age-dependent. Further research is required to determine the cell-specific transcriptional regulation and posttranscriptional regulation of these antimicrobial peptides.

Cationic PEGylated liposomes incorporating an antimicrobial peptide tilapia hepcidin 2-3: an adjuvant of epirubicin to overcome multidrug resistance in cervical cancer cells

Antimicrobial peptides (AMPs) have been recently evaluated as a new generation of adjuvants in cancer chemotherapy. In this study, we designed PEGylated liposomes encapsulating epirubicin as an antineoplastic agent and tilapia hepcidin 2–3, an AMP, as a multidrug resistance (MDR) transporter suppressor and an apoptosis/autophagy modulator in human cervical cancer HeLa cells. Cotreatment of HeLa cells with PEGylated liposomal formulation of epirubicin and hepcidin 2–3 significantly increased the cytotoxicity of epirubicin. The liposomal formulations of epirubicin and/or hepcidin 2–3 were found to noticeably escalate the intracellular H₂O₂ and O₂⁻ levels of cancer cells. Furthermore, these treatments considerably reduced the mRNA expressions of MDR protein 1, MDR-associated protein (MRP) 1, and MRP2. The addition of hepcidin 2–3 in liposomes was shown to markedly enhance the intracellular epirubicin uptake and mainly localized into the nucleus. Moreover, this formulation was also found to trigger apoptosis and autophagy in HeLa cells, as validated by significant increases in the expressions of cleaved poly ADP ribose polymerase, caspase-3, caspase-9, and light chain 3 (LC3)-II, as well as a decrease in mitochondrial membrane potential. The apoptosis induction was also confirmed by the rise in sub-G1 phase of cell cycle assay and apoptosis percentage of annexin V/propidium iodide assay. We found that liposomal epirubicin and hepcidin 2–3 augmented the accumulation of GFP-LC3 puncta as amplified by chloroquine, implying the involvement of autophagy. Interestingly, the partial inhibition of necroptosis and the epithelial–mesenchymal transition by this combination was also verified. Altogether, our results provide evidence that coincubation with PEGylated liposomes of hepcidin 2–3 and epirubicin caused programmed cell death in cervical cancer cells through modulation of multiple signaling pathways, including MDR transporters, apoptosis, autophagy, and/or necroptosis. Thus, this formulation may provide a new platform for the combined treatment of traditional chemotherapy and hepcidin 2–3 as a new adjuvant for effective MDR reversal.