Targeting tumors with peptides from natural sources

Anticancer activities of natural antimicrobial peptides from animals

Cancer is the most common cause of human death worldwide, posing a serious threat to human health and having a negative impact on the economy. In the past few decades, significant progress has been made in anticancer therapies, but traditional anticancer therapies, including radiation therapy, surgery, chemotherapy, molecular targeted therapy, immunotherapy and antibody-drug conjugates (ADCs), have serious side effects, low specificity, and the emergence of drug resistance. Therefore, there is an urgent need to develop new treatment methods to improve efficacy and reduce side effects. Antimicrobial peptides (AMPs) exist in the innate immune system of various organisms. As the most promising alternatives to traditional drugs for treating cancers, some AMPs also have been proven to possess anticancer activities, which are defined as anticancer peptides (ACPs). These peptides have the advantages of being able to specifically target cancer cells and have less toxicity to normal tissues. More and more studies have found that marine and terrestrial animals contain a large amount of ACPs. In this article, we introduced the animal derived AMPs with anti-cancer activity, and summarized the types of tumor cells inhibited by ACPs, the mechanisms by which they exert anti-tumor effects and clinical applications of ACPs.

Aberrant phase separation is a common killing strategy of positively charged peptides in biology and human disease

Positively charged repeat peptides are emerging as key players in neurodegenerative diseases. These peptides can perturb diverse cellular pathways but a unifying framework for how such promiscuous toxicity arises has remained elusive. We used mass-spectrometry-based proteomics to define the protein targets of these neurotoxic peptides and found that they all share similar sequence features that drive their aberrant condensation with these positively charged peptides. We trained a machine learning algorithm to detect such sequence features and unexpectedly discovered that this mode of toxicity is not limited to human repeat expansion disorders but has evolved countless times across the tree of life in the form of cationic antimicrobial and venom peptides. We demonstrate that an excess in positive charge is necessary and sufficient for this killer activity, which we name 'polycation poisoning'. These findings reveal an ancient and conserved mechanism and inform ways to leverage its design rules for new generations of bioactive peptides.

Development of sulfonium tethered peptides conjugated with HDAC inhibitor to improve selective toxicity for cancer cells

The anti-cancer peptides emerged as new weapons for cancer therapy due to their potent toxicity toward various cancer cells. However, their therapeutic promise is often limited by non-specific toxicity to normal cells. How to improve peptides' selectivity to cancer cells is always a matter to solve. In this manuscript, we designed a sulfonium tethered lytic peptide conjugated with a HDAC inhibitor to improve the selectivity of cancer cells. The sulfonium tethered lytic peptide with improved hydrophilicity and positive charge showed reduced toxicity to both cancer cells and normal cells. When conjugated with the HDAC inhibitor, this peptide showed increased toxicity to cancer cells. Besides, the stabilized peptide HDAC conjugate showed better serum stability than the linear peptide conjugate. For cellular function, the stabilized peptide conjugate could induce cancer cell apoptosis, cell cycle arrest, and influence multiple signal pathways through transcriptome analysis. This design may provide an alternative approach for the development of safe and effective anti-cancer drugs.

Quorum sensing in human gut and food microbiomes: Significance and potential for therapeutic targeting

Human gut and food microbiomes interact during digestion. The outcome of these interactions influences the taxonomical composition and functional capacity of the resident human gut microbiome, with potential consequential impacts on health and disease. Microbe-microbe interactions between the resident and introduced microbiomes, which likely influence host colonisation, are orchestrated by environmental conditions, elements of the food matrix, host-associated factors as well as social cues from other microorganisms. Quorum sensing is one example of a social cue that allows bacterial communities to regulate genetic expression based on their respective population density and has emerged as an attractive target for therapeutic intervention. By interfering with bacterial quorum sensing, for instance, enzymatic degradation of signalling molecules (quorum quenching) or the application of quorum sensing inhibitory compounds, it may be possible to modulate the microbial composition of communities of interest without incurring negative effects associated with traditional antimicrobial approaches. In this review, we summarise and critically discuss the literature relating to quorum sensing from the perspective of the interactions between the food and human gut microbiome, providing a general overview of the current understanding of the prevalence and influence of quorum sensing in this context, and assessing the potential for therapeutic targeting of quorum sensing mechanisms.

Anticancer peptides mechanisms, simple and complex

Peptide therapy has started since 1920s with the advent of insulin application, and now it has emerged as a new approach in treatment of diseases including cancer. Using anti-cancer peptides (ACPs) is a promising way of cancer therapy as ACPs are continuing to be approved and arrived at major pharmaceutical markets. Traditional cancer treatments face different problems like intensive adverse effects to patient's body, cell resistance to conventional chemical drugs and in some worse cases the occurrence of cell multidrug resistance (MDR) of cancerous tissues against chemotherapy. On the other hand, there are some benefits conceived for peptides usage in treatment of diseases specifically cancer, as these compounds present favorable characteristics such as smaller size, high activity, low immunogenicity, good biocompatibility in vivo, convenient and rapid way of synthesis, amenable to sequence modification and revision and there is no limitation for the type of cargo they carry. It is possible to achieve an optimum molecular and functional structure of peptides based on previous experience and bank of peptide motif data which may result in novel peptide design. Bioactive peptides are able to form pores in cell membrane and induce necrosis or apoptosis of abnormal cells. Moreover, recent researches have focused on the tumor recognizing peptide motifs with the ability to permeate to cancerous cells with the aim of cancer treatment at earlier stages. In this strategy the most important factors for addressing cancer are choosing peptides with easy accessibility to tumor cell without cytotoxicity effect towards normal cells. The peptides must also meet acceptable pharmacokinetic requirements. In this review, the characteristics of peptides and cancer cells are discussed. The various mechanisms of peptides' action proposed against cancer cells make the next part of discussion. It will be followed by giving information on peptides application, various methods of peptide designing along with introducing various databases. Future aspects of peptides for employing in area of cancer treatment come as conclusion at the end.

The dual interaction of antimicrobial peptides on bacteria and cancer cells; mechanism of action and therapeutic strategies of nanostructures

Microbial infection and cancer are two leading causes of global mortality. Discovering and developing new therapeutics with better specificity having minimal side-effects and no drug resistance are of an immense need. In this regard, cationic antimicrobial peptides (AMP) with dual antimicrobial and anticancer activities are the ultimate choice. For better efficacy and improved stability, the AMPs available for treatment still required to be modified. There are several strategies in which AMPs can be enhanced through, for instance, nano-carrier application with high selectivity and specificity enables researchers to estimate the rate of drug delivery to a particular tissue. In this review we present the biology and modes of action of AMPs for both anticancer and antimicrobial activities as well as some modification strategies to improve the efficacy and selectivity of these AMPs.

Biological aspects in controlling angiogenesis: current progress

All living beings continue their life by receiving energy and by excreting waste products. In animals, the arteries are the pathways of these transfers to the cells. Angiogenesis, the formation of the arteries by the development of pre-existed parental blood vessels, is a phenomenon that occurs naturally during puberty due to certain physiological processes such as menstruation, wound healing, or the adaptation of athletes' bodies during exercise. Nonetheless, the same life-giving process also occurs frequently in some patients and, conversely, occurs slowly in some physiological problems, such as cancer and diabetes, so inhibiting angiogenesis has been considered to be one of the important strategies to fight these diseases. Accordingly, in tissue engineering and regenerative medicine, the highly controlled process of angiogenesis is very important in tissue repairing. Excessive angiogenesis can promote tumor progression and lack of enough angiogensis can hinder tissue repair. Thereby, both excessive and deficient angiogenesis can be problematic, this review article introduces and describes the types of factors involved in controlling angiogenesis. Considering all of the existing strategies, we will try to lay out the latest knowledge that deals with stimulating/inhibiting the angiogenesis. At the end of the article, owing to the early-reviewed mechanical aspects that overshadow angiogenesis, the strategies of angiogenesis in tissue engineering will be discussed.

An Updated Review of Bioactive Peptides from Mushrooms in a Well-Defined Molecular Weight Range

Here, we report the current status of the bioactive peptides isolated and characterized from mushrooms during the last 20 years, considering ‘peptide’ a succession from to 2 to 100 amino acid residues. According to this accepted biochemical definition, we adopt ~10 kDa as the upper limit of molecular weight for a peptide. In light of this, a careful revision of data reported in the literature was carried out. The search revealed that in the works describing the characterization of bioactive peptides from mushrooms, not all the peptides have been correctly classified according to their molecular weight, considering that some fungal proteins (>10 kDa MW) have been improperly classified as ‘peptides’. Moreover, the biological action of each of these peptides, the principles of their isolation as well as the source/mushroom species were summarized. Finally, this review highlighted that these peptides possess antihypertensive, antifungal, antibiotic and antimicrobial, anticancer, antiviral, antioxidant and ACE inhibitory properties.

Anti-angiogenic peptides application in cancer therapy; a review

Cancer is a disease advanced via surplus angiogenesis. The development of new anti-angiogenic therapeutic agents with more efficacy and fewer side effects is still quite necessary. Conventional therapies saving the life of many cancer patients but due to drug resistance and lack of specificity utilizing these methods is faced with limits. Recently, new therapeutic agents have been developed and used to treat cancers such as scaffold proteins, monoclonal antibodies, tyrosine kinase inhibitors, and peptides. In antiangiogenic drug development, anti-angiogenic peptides design is a significant aim. Peptides have developed as substantial therapeutics that are being carefully investigated in angiogenesis-dependent diseases because of their high penetrating rate into the cancer cells, high specificity, and low toxicity. In this review, we focus on anti-angiogenic peptides in the field of cancer therapy that are designed, screened, or derived from nanobodies, mimotopes, phage displays, and natural resources.

Isolation and functionalities of bioactive peptides from fruits and vegetables: A reviews

Bioactive peptides have recently gained more research attention as potential therapies for the management of bodily disorders and metabolic syndromes of delicate health importance. On another note, there is a rising trend on a global scale for the consumption and adoption of fruit and vegetables for the fulfilment of dietary and health needs. Furthermore, fruits and vegetables are being more studied as base materials for the isolation of biologically functional components and accordingly, they have been investigated for their concomitant bioactive peptides. This review focuses on isolation and bio-functional properties of bioactive peptides from fruits and vegetables. This manuscript is potential in serving as a material collection for fundamental consultancy on peptides derived from fruits and vegetables, and further canvasses the necessitation for the use of these food materials as primal matter for such.

Recombinant active Peptides and their Therapeutic functions

Recombinant active peptides are utilized as diagnostic and biotherapeutics in various maladies and as bacterial growth inhibitors in the food industry. This consequently stimulated the need for recombinant peptides' production, which resulted in about 19 approved biotech peptides of 1-100 amino acids commercially available. While most peptides have been produced by chemical synthesis, the production of lengthy and complicated peptides comprising natural amino acids has been problematic with low quantity. Recombinant peptide production has become very vital, cost-effective, simple, environmentally friendly with satisfactory yields. Several reviews have focused on discussing expression systems, advantages, disadvantages, and alternatives strategies. Additionally, the information on the antimicrobial activities and other functions of multiple recombinant peptides is challenging to access and is scattered in literature apart from the food and drug administration (FDA) approved ones. From the reports that come to our knowledge, there is no existing review that offers substantial information on recombinant active peptides developed by researchers and their functions. This review provides an overview of some successfully produced recombinant active peptides of ≤100 amino acids by focusing on their antibacterial, antifungal, antiviral, anticancer, antioxidant, antimalarial, and immune-modulatory functions. It also elucidates their modes of expression that could be adopted and applied in future investigations. We expect that the knowledge available in this review would help researchers involved in recombinant active peptide development for therapeutic uses and other applications.

Anticancer Effect of Enterocin A-Colicin E1 Fusion Peptide on the Gastric Cancer Cell

Cancer is one of the most causes of death all over the world, although improvements in its treatment and recognition. Due to the limitations of common anticancer methods, including surgery, chemotherapy, and radiotherapy, attention has been drawn to other anti-cancer compounds, especially natural peptides such as bacteriocins. In this study, we used a combination of two bacteriocins, colicin E1 and enterocin A, against AGS gastric cancer cell lines. In order to evaluate anticancer properties of fusion peptide, we applied MTT assay, real-time PCR, and flow cytometry tests. This is the first report to show the cell growth inhibitory activity of the enterocin A in combination with colicin E1 against AGS human cancer cells. The results of this study showed that this fusion peptide at a concentration of 60.4 µg/mL and 24 h was able to kill half of the tested cancer cells, and treatment of the cells with this concentration increased the expression of bax and caspase 3 genes and reduced the expression of bacl-2 in 24 h. Flow cytometry analysis of annexin V-FITC/propidium iodide results also showed that our peptide was able to induce apoptosis in treated cells compared with control. Taken together, enterocin A-colicin E1 (ent A-col E1) can be considered as a good candidate for anticancer therapies.

Antimicrobial activity and cytotoxicity trait of a bioactive peptide purified from Lactococcus garvieae subsp. bovis BSN307T

A bioactive peptide of 8595 Da was purified from the cell free supernatant of Lactococcus garvieae subsp. bovis BSN307^T . MALDI MS/MS peptide mapping and the data base search displayed no significant similarity to any reported antimicrobial peptide of LAB. This peptide at a dose concentration of 200 µg ml^-1 inhibited the growth of both Gram-positive and Gram-negative bacteria by 58-89% and a dose of 500 µg ml^-1 scavenged 50% of DPPH-free radicals generated. Interestingly, cytotoxicity assay demonstrated that 17 µg ml^-1 of peptide selectively inhibited 50% proliferation of mammalian cancer cell lines HeLa and MCF-7 whereas normal H9c2 cells remained unaffected. Fluorescent microscopic analysis after DAPI nuclear staining of HeLa cells showed characteristics of apoptosis and activation of caspase-3 was ascertained by caspase-3 fluorescence assay.

Strategies to better treat glioblastoma: antiangiogenic agents and endothelial cell targeting agents

Glioblastoma multiforme (GBM) is the most prevalent and aggressive form of glioma, with poor prognosis and high mortality rates. As GBM is a highly vascularized cancer, antiangiogenic therapies to halt or minimize the rate of tumor growth are critical to improving treatment. In this review, antiangiogenic therapies, including small-molecule drugs, nucleic acids and proteins and peptides, are discussed. The authors further explore biomaterials that have been utilized to increase the bioavailability and bioactivity of antiangiogenic factors for better antitumor responses in GBM. Finally, the authors summarize the current status of biomaterial-based targeting moieties that target endothelial cells in GBM to more efficiently deliver therapeutics to these cells and avoid off-target cell or organ side effects.

Cancer Treatment by Caryophyllaceae-Type Cyclopeptides

Cancer is one of the leading diseases, which, in the most cases, ends with death and, thus, continues to be a major concern in human beings worldwide. The conventional anticancer agents used in the clinic often face resistance among many cancer diseases. Moreover, heavy financial costs preclude patients from continuing treatment. Bioactive peptides, active in several diverse areas against man's health problems, such as infection, pain, hypertension, and so on, show the potential to be effective in cancer treatment and may offer promise as better candidates for combating cancer. Cyclopeptides, of natural or synthetic origin, have several advantages over other drug molecules with low toxicity and low immunogenicity, and they are easily amenable to several changes in their sequences. Given their many demanded homologues, they have created new hope of discovering better compounds with desired properties in the field of challenging cancer diseases. Caryophyllaceae-type cyclopeptides show several biological activities, including cancer cytotoxicity. These cyclopeptides have been discovered in several plant families but mainly are from the Caryophyllaceae family. In this review, a summary of biological activities found for these cyclopeptides is given; the focus is on the anticancer findings of these peptides. Among these cyclopeptides, information about Dianthins (including Longicalycinin A), isolated from different species of Caryophyllaceae, as well as their synthetic analogues is detailed. Finally, by comparing their structures and cytotoxic activities, finding the common figures of these kinds of cyclopeptides as well as their possible future place in the clinic for cancer treatment is put forward.

Bioactive peptides from food fermentation: A comprehensive review of their sources, bioactivities, applications, and future development

Bioactive peptides (BPs) are specific protein fragments that exert various beneficial effects on human bodies and ultimately influence health, depending on their structural properties and amino acid composition and sequences. By offering promising solutions to solve diverse health issues, the production, characterization, and applications of food-derived BPs have drawn great interest in the current literature and are of particular interest to the food and pharmaceutical industries. The microbial fermentation of protein from various sources is indubitably a novel way to produce BPs with numerous beneficial health effects. Apart from its lower cost as compared to enzymes, the BPs produced from microbial fermentation can be purified without further hydrolysis. Despite these features, current literature shows dearth of information on the BPs produced from food via microbial fermentation. Hence, there is a strong necessity to explore the BPs obtained from food fermentation for the development of commercial nutraceuticals and functional foods. As such, this review focuses on the production of BPs from different food sources, including the extensively studied milk and milk products, with emphasis on microbial fermentation. The structure-activity (antihypertensive, antioxidant, antimicrobial, opiate-like, anti-inflammatory, anticancer/antiproliferative, antithrombotic, hypolipidemic, hypocholesterolemic, and mineral binding) relationship, potential applications, future development, and challenges of BPs obtained from food fermentation are also discussed.

Experimental analysis of T cell epitopes for designing liver cancer vaccine predicted by system-level immunoinformatics approach

Liver cancer is a worldwide disease, and, currently, due to the poor prognostic and therapeutic options of liver cancer, we investigated the T cell epitopes as potential therapeutic vaccine candidates to get the benefit of experimental processes and utilize the complete ability of the immune system compared with other artificial ex vivo proliferation of T cells. Activation of T cells targets and kills several tumors, developing a strong rationale for the improvement of immunotherapeutic strategies to cancer therapy. To predict T cell epitopes for liver cancer, we designed a comprehensive immunoinformatics framework involving data mining, immunogenicity prediction, functional proteomic analysis, conservation studies, molecular modeling, and in vivo validation analysis. We found the binding affinity of antigenic peptides with major histocompatibility complex (MHC) I molecules to control the cancerous activity. Five extracellular antigenic proteins, including complement protein (C6), serotransferrin, coagulation factor XIII B, serum albumin (ALB), and prothrombin, were identified. We predicted and synthesized T cell epitopes to human leukocytes antigen-A*01:01 allele of MHC class I molecule. The hematological assay and IgG ELISA showed that C6 and ALB epitopes induced the production of lymphocytes, granulocytes, and peptide-specific IgG in immunized rats. We observed substantial high levels of granzymes B in serum samples of C6 and ALB compared with control, indicating the activity of cytotoxic T cells. We concluded that C6 and ALB are likely to contain potential epitopes for the induction of protective effector molecules, supporting the feasibility of therapeutic peptide-based vaccine for liver cancer.NEW & NOTEWORTHY We observed substantial high levels of granzymes B in serum samples of component C6 (C6) and albumin (ALB) compared with control, indicating the activity of cytotoxic T cells. We concluded that C6 and ALB are likely to contain potential epitopes for the induction of protective effector molecules, supporting the feasibility of therapeutic peptide-based vaccine for liver cancer.

Recent Advancements of Magnetic Nanomaterials in Cancer Therapy

Magnetic nanomaterials belong to a class of highly-functionalizable tools for cancer therapy owing to their intrinsic magnetic properties and multifunctional design that provides a multimodal theranostics platform for cancer diagnosis, monitoring, and therapy. In this review article, we have provided an overview of the various applications of magnetic nanomaterials and recent advances in the development of these nanomaterials as cancer therapeutics. Moreover, the cancer targeting, potential toxicity, and degradability of these nanomaterials has been briefly addressed. Finally, the challenges for clinical translation and the future scope of magnetic nanoparticles in cancer therapy are discussed.

Inhibitory Effects of Multivalent Polypeptides on the Proliferation and Metastasis of Breast Cancer Cells

The susceptibility of peptide drugs to enzymatic degradation has limited their clinical applications. To overcome this limitation, we attached the peptide tyroserleutide (YSL) to a molecular scaffold in order to produce homogeneous monovalent, bivalent, tetravalent, and octavalent YSL dendrimers with highly ordered secondary structures. These multivalent YSL dendrimers were resistant to proteolysis and were better able to induce cytotoxicity in tumor cells in vitro as compared with monomeric peptides. These multivalent YSL dendrimers were also better able to constrain tumor cell metastasis. Compared with monovalent YSL, the multivalent YSL dendrimers displayed enhanced in vivo antitumor activity and suppressed tumor growth and metastasis in BALB/c mice bearing 4T1 tumors. These findings indicate that multivalence can significantly enhance ligand potency and represent a potential method for the development of peptide drugs with high therapeutic potential.

Improving Health-Promoting Effects of Food-Derived Bioactive Peptides through Rational Design and Oral Delivery Strategies

Over the last few decades, scientific interest in food-derived bioactive peptides has grown as an alternative to pharmacological treatments in the control of lifestyle-associated diseases, which represent a serious health problem worldwide. Interest has been directed towards the control of hypertension, the management of type 2 diabetes and oxidative stress. Many food-derived antihypertensive peptides act primarily by inhibiting angiotensin I-converting enzyme (ACE), and to a lesser extent, renin enzyme activities. Antidiabetic peptides mainly inhibit dipeptidyl peptidase-IV (DPP-IV) activity, whereas antioxidant peptides act through inactivation of reactive oxygen species, free radicals scavenging, chelation of pro-oxidative transition metals and promoting the activities of intracellular antioxidant enzymes. However, food-derived bioactive peptides have intrinsic weaknesses, including poor chemical and physical stability and a short circulating plasma half-life that must be addressed for their application as nutraceuticals or in functional foods. This review summarizes the application of common pharmaceutical approaches such as rational design and oral delivery strategies to improve the health-promoting effects of food-derived bioactive peptides. We review the structural requirements of antihypertensive, antidiabetic and antioxidant peptides established by integrated computational methods and provide relevant examples of effective oral delivery systems to enhance solubility, stability and permeability of bioactive peptides.

Mussel-Derived, Cancer-Targeting Peptide as pH-Sensitive Prodrug Nanocarrier

In this work, we prepared a novel cancer chemotherapeutic nanocarrier through the self-assembly of a mussel-derived, cancer-targeting peptide with a pH-sensitive conjugation of antitumor drugs. The biomimetic peptide was designed with a fluorescent molecule fluorescein isothiocyanate for imaging, a RGD sequence for cancer-targeting and tetravalent catechol groups for dynamic conjugation of the antitumor drug bortezomib via pH-cleavable boronic acid-catechol esters. Our study demonstrated that the peptide-based prodrug nanocarrier dramatically the enhanced specific cellular uptake and cytotoxicity toward human breast cancer cells in vitro in comparison with free drug and nontargeting control nanoparticles. Likewise, the prodrug nanocarrier showed improved therapeutic efficacy and low systematic toxicity in vivo. Considering highly biomimetic nature of the peptide-based nanocarriers, rapid drug release from the dynamically conjugated prodrugs, and convenience of introducing cancer-targeting activity onto this nanosystem, we believe our work would provide new ideas for the development of intelligent and biocompatible drug delivery systems to improve the chemotherapy efficacy in clinic. Furthermore, the pH-sensitive drug conjugation mechanism on peptide-based nanocarriers would provide a hint for the exploitation of dynamic prodrug strategies and the development of highly biocompatible nanocarriers using biogenic materials, e.g., the proteinogenic nanomaterials decorated with drugs through dynamic covalent chemistry.

Are peptides a solution for the treatment of hyperactivated JAK3 pathways?

While the inactivation mutations that eliminate JAK3 function lead to the immunological disorders such as severe combined immunodeficiency, activation mutations, causing constitutive JAK3 signaling, are known to trigger various types of cancer or are responsible for autoimmune diseases, such as rheumatoid arthritis, psoriasis, or inflammatory bowel diseases. Treatment of hyperactivated JAK3 is still an obstacle, due to different sensibility of mutation types to conventional drugs and unwanted side effects, because these drugs are not absolutely specific for JAK3, thus inhibiting other members of the JAK family, too. Lack of information, in which way sole inhibition of JAK3 is necessary for elimination of the disease, calls for the development of isoform-specific JAK3 inhibitors. Beside this strategy, up to date peptides are a rising alternative as chemo- or immunotherapeutics, but still sparsely represented in drug development and clinical trials. Beyond a possible direct inhibition function, crossing the cancer cell membrane and interfering in disease-causing pathways or triggering apoptosis, peptides could be used in future as adjunct remedies to potentialize traditional therapy and preserve non-affected cells. To discuss such feasible topics, this review deals with the knowledge about the structure-function of JAK3 and the actual state-of-the-art of isoform-specific inhibitor development, as well as the function of currently approved drugs or those currently being tested in clinical trials. Furthermore, several strategies for the application of peptide-based drugs for cancer therapy and the physicochemical and structural relations to peptide efficacy are discussed, and an overview of peptide sequences, which were qualified for clinical trials, is given.

Molecular, Biological and Structural Features of VL CDR-1 Rb44 Peptide, Which Targets the Microtubule Network in Melanoma Cells

Microtubules are important drug targets in tumor cells, owing to their role in supporting and determining the cell shape, organelle movement and cell division. The complementarity-determining regions (CDRs) of immunoglobulins have been reported to be a source of anti-tumor peptide sequences, independently of the original antibody specificity for a given antigen. We found that, the anti-Lewis B mAb light-chain CDR1 synthetic peptide Rb44, interacted with microtubules and induced depolymerization, with subsequent degradation of actin filaments, leading to depolarization of mitochondrial membrane-potential, increase of ROS, cell cycle arrest at G2/M, cleavage of caspase-9, caspase-3 and PARP, upregulation of Bax and downregulation of Bcl-2, altogether resulting in intrinsic apoptosis of melanoma cells. The in vitro inhibition of angiogenesis was also an Rb44 effect. Peritumoral injection of Rb44L1 delayed growth of subcutaneously grafted melanoma cells in a syngeneic mouse model. L1-CDRs from immunoglobulins and their interactions with tubulin-dimers were explored to interpret effects on microtubule stability. The opening motion of tubulin monomers allowed for efficient L1-CDR docking, impairment of dimer formation and microtubule dissociation. We conclude that Rb44 V_L-CDR1 is a novel peptide that acts on melanoma microtubule network causing cell apoptosis in vitro and melanoma growth inhibition in vivo.

Nisin Induces Cytotoxicity and Apoptosis in Human Asterocytoma Cell Line (SW1088)

Background: Nisin is a member of the group of anti-microbial peptides which are considered as bacteriocins, but it possesses a vast range of activities. Astrocytoma is among the most prevalent types of brain tumor globally. Considering all facts about this peptide, the aim of the present study was the evaluation of any impact of nisin on proliferation and apoptosis of an astrocytoma cell line (SW1088). Methods: The SW1088 cell line was purchased from the Pasteur Institute of Iran and treated with various concentrations of Nisin. Nisin-induced cell toxicity and apoptosis were detected by both MTT assay and annexin V-FITC /propidium iodide (PI) staining. Result: In current study we observed that the cell death and apoptosis were significantly increased following nisin treatment, as compared to the control group. Conclusion: These results open a new window for establishment promising approaches with the concept of anti-cancer therapy by nisin in the future.

Tryptophan-Containing Dual Neuroprotective Peptides: Prolyl Endopeptidase Inhibition and Caenorhabditis elegans Protection from β-Amyloid Peptide Toxicity

Neuroprotective peptides represent an attractive pharmacological strategy for the prevention or treatment of age-related diseases, for which there are currently few effective therapies. Lactoferrin (LF)-derived peptides (PKHs) and a set of six rationally-designed tryptophan (W)-containing heptapeptides (PACEIs) were characterized as prolyl endopeptidase (PEP) inhibitors, and their effect on β-amyloid peptide (Aβ) toxicity in a Caenorhabditis elegans model of Alzheimer's disease (AD) was evaluated. Two LF-derived sequences, PKH8 and PKH11, sharing a W at the C-terminal end, and the six PACEI heptapeptides (PACEI48L to PACEI53L) exhibited significant in vitro PEP inhibition. The inhibitory peptides PKH11 and PACEI50L also alleviated Aβ-induced paralysis in the in vivo C. elegans model of AD. Partial or total loss of the inhibitory effect on PEP was achieved by the substitution of W residues in PKH11 and PACEI50L and correlated with the loss of protection against Aβ toxicity, pointing out the relevance of W on the neuroprotective activity. Further experiments suggest that C. elegans protection might not be mediated by an antioxidant mechanism but rather by inhibition of Aβ oligomerization and thus, amyloid deposition. In conclusion, novel natural and rationally-designed W-containing peptides are suitable starting leads to design effective neuroprotective agents.

Antineoplastic activity of linear leucine homodipeptides and their potential mechanisms of action

Galaxamide is a rare cyclic homopentapeptide composed of three leucines and two N-methyl leucines isolated from marine algae Galaxaura filamentosa. The strong antitumor activity of this compound makes it a promising candidate for tumor therapy. The synthesis of galaxamide, however, is a complex process, and it has poor water solubility. On the basis of its special chemical composition, we designed a series of linear leucine homopeptides. Among seven dipeptide derivatives, five compounds with terminal protection groups and methyl substitution of the hydrogen in the amido group showed remarkable inhibitory effects against various cancer cells. N-tertbutyl-D-leucine-N-methyl-D-leucinebenzyl (A7), the only stereomer condensed by two D-leucines, showed the highest antineoplastic activity. A7-treated cells showed cell cycle arrest and morphological changes typical of cells undergoing apoptosis. The population of Annexin-V positive/propidium iodide-negative cells also increased, indicating the induction of early apoptosis. A7 promoted the cleavage of caspase-9 and caspase-3, as well as increased intracellular Ca levels and decreased the mitochondrial membrane potential. Collectively, certain linear leucine dipeptides derived from cyclic pentapeptide are able to inhibit tumor cell proliferation through cell cycle arrest and apoptosis induction. The N-methyl group in the side chain and the D/L conformation of the amino-acid residue are critical for their activity.

Synthesis and biological evaluation of cyclopeptide GG-8-6 and its analogues as anti-hepatocellular carcinoma agents

GG-8-6, cyclo-(Val-Leu-Pro-Ile-Leu-Leu-Leu-Val-Leu, compound 1), and its twelve analogues (compound 2-13) were synthesized based on the lead compound Grifficyclocin B, a cyclic peptide with anti-tumor activity which was isolated from the plants of Goniothalamus species (Annonaceae). The bioassay results showed that these synthetic cyclopeptides exhibited different extent of cytotoxicity against human hepatocellular carcinoma cell lines. Among them, GG-8-6 (1) was the most active compound with IC₅₀ values of 6.38 μM and 12.22 μM against SMMC-7721 and HepG2, respectively. Further studies on the mechanism demonstrated that GG-8-6 (1) could induce apoptosis and G2/M arrest of HCC cells, and the activation of caspase pathways was probably involved. In vivo anti-tumor experiments showed that GG-8-6 (1) could significantly inhibit the growth of tumor in the mouse xenograft tumor model. At the dose of 40 mg/kg, the inhibition ratio was 67.9% without weight loss. Our results suggested that GG-8-6 (1), a new cyclic peptide, might be a potential candidate for developing new anti-HCC drug in the coming future.

Anti-Cancer Activity of Maize Bioactive Peptides

Cancer is one of the main chronic degenerative diseases worldwide. In recent years, consumption of whole-grain cereals and their derivative food products has been associated with a reduced risk of various types of cancer. The main biomolecules in cereals include proteins, peptides, and amino acids, all of which are present in different quantities within the grain. Some of these peptides possess nutraceutical properties and exert biological effects that promote health and prevent cancer. In this review, we report the current status and advances in knowledge regarding the bioactive properties of maize peptides, such as antioxidant, antihypertensive, hepatoprotective, and anti-tumor activities. We also highlight the potential biological mechanisms through which maize bioactive peptides exert anti-cancer activity. Finally, we analyze and emphasize the potential applications of maize peptides.

Protective roles of bioactive peptides during ischemia-reperfusion injury: From bench to bedside

Ischemia-reperfusion (I/R) is a well-known pathological condition which may lead to disability and mortality. I/R injury remains an unresolved and complicated situation in a number of clinical conditions, such as cardiac arrest with successful reanimation, as well as ischemic events in brain and heart. Peptides have many attractive advantages which make them suitable candidate drugs in treating I/R injury, such as low toxicity and immunogenicity, good solubility property, distinct tissue distribution pattern, and favorable pharmacokinetic profile. An increasing number of studies indicate that peptides could protect against I/R injury in many different organs and tissues. Peptides also face several therapeutic challenges that limit their clinical application. In this review, we present the mechanisms of action of peptides in reducing I/R injury, as well as further discuss modification strategies to improve the functional properties of bioactive peptides.

Lunasin: A promising polypeptide for the prevention and treatment of cancer

Strategies for the treatment of cancer remain unsatisfactory due to the poor understanding of the complicated underlying molecular mechanisms of carcinogenesis. A number of types of cancer exhibit a marked association with dietary habits and lifestyles. Therefore, the modulation of dietary habits or lifestyles may be an effective strategy for preventing the formation and progression of cancer. Proteins and polypeptides from soybean have been developed as healthcare products due to their marked activity in inhibiting the progression of cancer at various stages. Lunasin, containing 43 amino acid residues, is one such example of a soybean-derived polypeptide that has been demonstrated to exhibit marked anti-cancer activity. In the present review, studies of the underlying molecular mechanisms and potential advantages of lunasin in the prevention and treatment of cancer have been examined, to provide a theoretical reference for the development of natural product-based agents or healthcare products for the prevention and treatment of cancer.

An in-tether chiral center modulates the proapoptotic activity of the KLA peptide

We have utilized a novel in-tether chiral center induced helicity strategy (CIH) to develop a potent apoptosis inducer based on apoptotic KLA peptide. For our constructed peptides, the CIH-KLA-(R) epimer exhibited superior cellular uptakes and special mitochondrial targeting when compared with its S counterpart.

AC-1001 H3 CDR peptide induces apoptosis and signs of autophagy in vitro and exhibits antimetastatic activity in a syngeneic melanoma model

Antibody‐derived peptides modulate functions of the immune system and are a source of anti‐infective and antitumor substances. Recent studies have shown that they comprise amino acid sequences of immunoglobulin complementarity‐determining regions, but also fragments of constant regions. V_H CDR3 of murine mAb AC‐1001 displays antimetastatic activities using B16F10‐Nex2 murine melanoma cells in a syngeneic model. The peptide was cytotoxic in vitro in murine and human melanoma cells inducing reactive oxygen species (ROS) and apoptosis by the intrinsic pathway. Signs of autophagy were also suggested by the increased expression of LC3/LC3II and Beclin 1 and by ultrastructural evidence. AC‐1001 H3 bound to both G‐ and F‐actin and inhibited tumor cell migration. These results are important evidence of the antitumor activity of Ig CDR‐derived peptides.

Pharmacological research on natural substances in Latvia: Focus on lunasin, betulin, polyprenol and phlorizin

In this concise review the current research in plant bioactive compound studies in Latvia is described. The paper summarizes recent studies on substances from edible plants (e.g., cereals and apples) or their synthetic analogues, such as peptide lunasin, as well as substances isolated from inedible plants (e.g., birch and conifer), such as pentacyclic triterpenes (e.g., betulin, betulinic acid, and lupeol) and polyprenols. Latvian researchers have been first to demonstrate the presence of lunasin in triticale and oats. Additionally, the impact of genotype on the levels of lunasin in cereals was shown. Pharmacological studies have revealed effects of lunasin and synthetic triterpenes on the central nervous system in rodents. We were first to show that synthetic lunasin causes a marked neuroleptic/cataleptic effect and that betulin antagonizes bicuculline-induced seizures (a GABA A receptor antagonist). Studies on the mechanisms of action showed that lunasin binds to dopamine D1 receptors and betulin binds to melanocortin and gamma-aminobutyric acid A receptors therefore we suggest that these receptors play an essential role in lunasin's and betulin's central effects. Recent studies on conifer polyprenols demonstrated the ability of polyprenols to prevent statin-induced muscle weakness in a rat model. Another study on plant compounds has demonstrated the anti-hyperglycemic activity of phlorizin-containing unripe apple pomace in healthy volunteers. In summary, research into plant-derived compounds in Latvia has been focused on fractionating, isolating and characterizing of lunasin, triterpenes, polyprenols and phlorizin using in vitro, and in vivo assays, and human observational studies.

Small gold nanocomposites obtained in reverse micelles as nanoreactors. Effect of surfactant, optical properties and activity against Pseudomonas aeruginosa

High antibacterial convergence of an antimicrobial synthetic peptide and small gold nanoparticles against Pseudomonas aeruginosa.

Generation of new peptide-Fc fusion proteins that mediate antibody-dependent cellular cytotoxicity against different types of cancer cells

Antibody-dependent cellular cytotoxicity (ADCC), a key effector function for the clinical effectiveness of monoclonal antibodies, is triggered by the engagement of the antibody Fc domain with the Fcγ receptors expressed by innate immune cells such as natural killer (NK) cells and macrophages. Here, we fused cancer cell-binding peptides to the Fc domain of human IgG1 to engineer novel peptide-Fc fusion proteins with ADCC activity. The designed fusion proteins were expressed in human embryonic kidney 293T cells, followed by purification and characterization by western blots. One of the engineered variants (WN-Fc), bound with high affinity to a wide range of solid tumor cell lines (e.g., colon, lung, prostate, skin, ovarian, and mammary tumors). Treatment of cancer cells with the engineered peptide-Fc fusions in the presence of effector NK cells potentially enhanced cytotoxicity, degranulation, and interferon-γ production by NK cells when compared to cells treated with the Fc control. The presence of competing peptides inhibited NK cell activation. Furthermore, a bispecific peptide-Fc fusion protein activated NK cells against HER-1- and/or HER-2-expressing cancer cells. Collectively, the engineered peptide-Fc fusions constitute a new promising strategy to recruit and activate NK cells against tumor cells, a primary goal of cancer immunotherapy.

Peptide-Based Treatment: A Promising Cancer Therapy

Many new therapies are currently being used to treat cancer. Among these new methods, chemotherapy based on peptides has been of great interest due to the unique advantages of peptides, such as a low molecular weight, the ability to specifically target tumor cells, and low toxicity in normal tissues. In treating cancer, peptide-based chemotherapy can be mainly divided into three types, peptide-alone therapy, peptide vaccines, and peptide-conjugated nanomaterials. Peptide-alone therapy may specifically enhance the immune system's response to kill tumor cells. Peptide-based vaccines have been used in advanced cancers to improve patients' overall survival. Additionally, the combination of peptides with nanomaterials expands the therapeutic ability of peptides to treat cancer by enhancing drug delivery and sensitivity. In this review, we mainly focus on the new advances in the application of peptides in treating cancer in recent years, including diagnosis, treatment, and prognosis.

Effect of nisin and doxorubicin on DMBA-induced skin carcinogenesis--a possible adjunct therapy

In view of the emergence of multidrug-resistant cancer cells, there is a need for therapeutic alternatives. Keeping this in mind, the present study was aimed at evaluating the synergism between nisin (an antimicrobial peptide) and doxorubicin (DOX) against DMBA-induced skin carcinogenesis. The possible tumoricidal activity of the combination was evaluated in terms of animal bioassay observations, changes in hisotological architecture of skin tissues, in situ apoptosis assay (TUNEL assay) and in terms of oxidant and antioxidant status of the skin tissues. In vivo additive effect of the combination was evidenced by larger decreases in mean tumour burden and tumour volume in mice treated with the combination than those treated with the drugs alone. Histological observations indicated that nisin-DOX therapy causes chromatin condensation and marginalisation of nuclear material in skin tissues of treated mice which correlated well with the results of TUNEL assay wherein a marked increase in the rate of apoptosis was revealed in tissues treated with the combination. A slightly increased oxidative stress in response to the adjunct therapy as compared to dox-alone-treated group was revealed by levels of lipid peroxidation (LPO) and nitrite generation in skin tissue-treated mice. An almost similar marginal enhancement in superoxide dismutase levels corresponding with a decrease in catalase activity could also be observed in nisin + DOX-treated groups as compared to nisin and dox-alone-treated groups. These results point towards the possible use of nisin as an adjunct to doxorubicin may help in developing alternate strategies to combat currently developing drug resistance in cancer cells.