Inhibition of tumor growth and elimination of multiple metastases in human prostate and breast xenografts by systemic inoculation of a host defense-like lytic peptide

Polypeptides-Based Nanocarriers in Tumor Therapy

Cancer remains a worldwide problem, and new treatment strategies are being actively developed. Peptides have the characteristics of good biocompatibility, strong targeting, functional diversity, modifiability, membrane permeable ability, and low immunogenicity, and they have been widely used to construct targeted drug delivery systems (DDSs). In addition, peptides, as endogenous substances, have a high affinity, which can not only regulate immune cells but also work synergistically with drugs to kill tumor cells, demonstrating significant potential for application. In this review, the latest progress of polypeptides-based nanocarriers in tumor therapy has been outlined, focusing on their applications in killing tumor cells and regulating immune cells. Additionally, peptides as carriers were found to primarily provide a transport function, which was also a subject of interest to us. At the end of the paper, the shortcomings in the construction of peptide nano-delivery system have been summarized, and possible solutions are proposed therein. The application of peptides provides a promising outlook for cancer treatment, and we hope this article can provide in-depth insights into possible future avenues of exploration.

Polysulfonium: Unveiling a Bioactive Polymer to Induce Immunogenic Cell Death for Anticancer Therapy

Here we report a brand-new bioactive polymer featuring sulfonium moieties that exhibits the capability of inducing immunogenic cell death (ICD) for anticancer therapy. The optimized polysulfonium presents a wide spectrum of potent anticancer activity and remarkable selectivity. In-depth mechanistic studies reveal that the polymer exerts its cytotoxic effects on cancer cells through a membrane-disrupting mechanism. This further initiates the release of a plethora of damage-associated molecular patterns, effectively triggering ICD and resulting in systemic anticancer immune responses. Notably, the compound demonstrated significant efficacy in suppressing tumor growth in the B16-F10 melanoma tumor model. Furthermore, it exhibits robust immune memory effects, effectively suppressing tumor recurrence and metastasis in both the rechallenge model and the lung metastatic tumor model. To the best of our knowledge, the study represents the pioneering exportation of cationic polysulfoniums, showcasing not only their remarkable safety and efficacy against primary tumors but also their unique ability in activating long-term immune memory.

A Lipid-Sensitive Spider Peptide Toxin Exhibits Selective Anti-Leukemia Efficacy through Multimodal Mechanisms

Anti-cancer peptides (ACPs) represent a promising potential for cancer treatment, although their mechanisms need to be further elucidated to improve their application in cancer therapy. Lycosin-I, a linear amphipathic peptide isolated from the venom of Lycosa singorensis, shows significant anticancer potential. Herein, it is found that Lycosin-I, which can self-assemble into a nanosphere structure, has a multimodal mechanism of action involving lipid binding for the selective and effective treatment of leukemia. Mechanistically, Lycosin-I selectively binds to the K562 cell membrane, likely due to its preferential interaction with negatively charged phosphatidylserine, and rapidly triggers membrane lysis, particularly at high concentrations. In addition, Lycosin-I induces apoptosis, cell cycle arrest in the G1 phase and ferroptosis in K562 cells by suppressing the PI3K-AKT-mTOR signaling pathway and activating cell autophagy at low concentrations. Furthermore, intraperitoneal injection of Lycosin-I inhibits tumor growth of K562 cells in a nude mouse xenograft model without causing side effects. Collectively, the multimodal effect of Lycosin-I can provide new insights into the mechanism of ACPs, and Lycosin-I, which is characterized by high potency and specificity, can be a promising lead for the development of anti-leukemia drugs.

Development of Nontoxic Peptides for Lipopolysaccharide Neutralization and Sepsis Treatment

Host defense peptides (HDPs), also named antimicrobial peptides (AMPs), are increasingly being recognized for serving multiple functions in protecting the host from infection and disease. Previous studies have shown that various HDPs can also neutralize lipopolysaccharide (LPS, endotoxin), as well as lipoteichoic acid (LTA), inducing macrophage activation. However, antimicrobial activity is usually accompanied by systemic toxicity which makes it difficult to use HDPs as antiendotoxin agents. Here we report that key parameters can uncouple these two functions yielding nontoxic peptides with potent LPS and LTA neutralization activities in vitro and in animal models. The data reveal that peptide length, the number, and the placement of positive charges are important parameters involved in LPS neutralization. Crucially, the peptide exhibited a separation between its membrane-disrupting and antimicrobial properties, effectively decoupling them from its ability to neutralize LPS. This essential distinction prevented systemic toxicity and led to the peptide's complete rescue of mice suffering from severe septic shock in two distinct models. Strong binding to LPS, changes in structure, and oligomerization state upon LPS binding were important factors that determined the activity of the peptides. In the face of the increasing threat of septic shock worldwide, it is crucial to grasp how we can neutralize harmful substances like LPS. This knowledge is vital for creating nontoxic treatments for sepsis.

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.

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.

Application Value of Antimicrobial Peptides in Gastrointestinal Tumors

Gastrointestinal cancer is a common clinical malignant tumor disease that seriously endangers human health and lacks effective treatment methods. As part of the innate immune defense of many organisms, antimicrobial peptides not only have broad-spectrum antibacterial activity but also can specifically kill tumor cells. The positive charge of antimicrobial peptides under neutral conditions determines their high selectivity to tumor cells. In addition, antimicrobial peptides also have unique anticancer mechanisms, such as inducing apoptosis, autophagy, cell cycle arrest, membrane destruction, and inhibition of metastasis, which highlights the low drug resistance and high specificity of antimicrobial peptides. In this review, we summarize the related studies on antimicrobial peptides in the treatment of digestive tract tumors, mainly oral cancer, esophageal cancer, gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer. This paper describes the therapeutic advantages of antimicrobial peptides due to their unique anticancer mechanisms. The length, net charge, and secondary structure of antimicrobial peptides can be modified by design or modification to further enhance their anticancer effects. In summary, as an emerging cancer treatment drug, antimicrobial peptides need to be further studied to realize their application in gastrointestinal cancer diseases.

ΔM4: Membrane-Active Peptide with Antitumoral Potential against Human Skin Cancer Cells

Peptides have become attractive potential agents due to their affinity to cancer cells. In this work, the biological activity of the peptide ΔM4 against melanoma cancer cell line A375, epidermoid carcinoma cell line A431, and non-tumoral HaCaT cells was evaluated. The cytotoxic MTT assay demonstrates that ΔM4 show five times more activity against cancer than non-cancer cells. The potential membrane effect of ΔM4 was evaluated through lactate dehydrogenase release and Sytox uptake experiments. The results show a higher membrane activity of ΔM4 against A431 in comparison with the A375 cell line at a level of 12.5 µM. The Sytox experiments show that ΔM4 has a direct effect on the permeability of cancer cells in comparison with control cells. Infrared spectroscopy was used to study the affinity of the peptide to membranes resembling the composition of tumoral and non-tumoral cells. The results show that ΔM4 induces a fluidization effect on the tumoral lipid system over 5% molar concentration. Finally, to determine the appearance of phosphatidylserine on the surface of the cell, flow cytometry analyses were performed employing an annexin V-PE conjugate. The results suggest that 12.5 µM of ΔM4 induces phosphatidylserine translocation in A375 and A431 cancer cells. The findings of this study support the potential of ΔM4 as a selective agent for targeting cancer cells. Its mechanism of action demonstrated selectivity, membrane-disrupting effects, and induction of phosphatidylserine translocation.

Pyrazole-Enriched Cationic Nanoparticles Induced Early- and Late-Stage Apoptosis in Neuroblastoma Cells at Sub-Micromolar Concentrations

Neuroblastoma (NB) is a severe form of tumor occurring mainly in young children and originating from nerve cells found in the abdomen or next to the spine. NB needs more effective and safer treatments, as the chance of survival against the aggressive form of this disease are very small. Moreover, when current treatments are successful, they are often responsible for unpleasant health problems which compromise the future and life of surviving children. As reported, cationic macromolecules have previously been found to be active against bacteria as membrane disruptors by interacting with the negative constituents of the surface of cancer cells, analogously inducing depolarization and permeabilization, provoking lethal damage to the cytoplasmic membrane, and cause loss of cytoplasmic content and consequently, cell death. Here, aiming to develop new curative options for counteracting NB cells, pyrazole-loaded cationic nanoparticles (NPs) (BBB4-G4K and CB1H-P7 NPs), recently reported as antibacterial agents, were assayed against IMR 32 and SHSY 5Y NB cell lines. Particularly, while BBB4-G4K NPs demonstrated low cytotoxicity against both NB cell lines, CB1H-P7 NPs were remarkably cytotoxic against both IMR 32 and SHSY 5Y cells (IC50 = 0.43–0.54 µM), causing both early-stage (66–85%) and late-stage apoptosis (52–65%). Interestingly, in the nano-formulation of CB1H using P7 NPs, the anticancer effects of CB1H and P7 were increased by 54–57 and 2.5–4-times, respectively against IMR 32 cells, and by 53–61 and 1.3–2 times against SHSY 5Y cells. Additionally, based on the IC50 values, CB1H-P7 was also 1-12-fold more potent than fenretinide, an experimental retinoid derivative in a phase III clinical trial, with remarkable antineoplastic and chemopreventive properties. Collectively, due to these results and their good selectivity for cancer cells (selectivity indices = 2.8–3.3), CB1H-P7 NPs represent an excellent template material for developing new treatment options against NB.

Anti-Cancer Peptides: Status and Future Prospects

The dramatic rise in cancer incidence, alongside treatment deficiencies, has elevated cancer to the second-leading cause of death globally. The increasing morbidity and mortality of this disease can be traced back to a number of causes, including treatment-related side effects, drug resistance, inadequate curative treatment and tumor relapse. Recently, anti-cancer bioactive peptides (ACPs) have emerged as a potential therapeutic choice within the pharmaceutical arsenal due to their high penetration, specificity and fewer side effects. In this contribution, we present a general overview of the literature concerning the conformational structures, modes of action and membrane interaction mechanisms of ACPs, as well as provide recent examples of their successful employment as targeting ligands in cancer treatment. The use of ACPs as a diagnostic tool is summarized, and their advantages in these applications are highlighted. This review expounds on the main approaches for peptide synthesis along with their reconstruction and modification needed to enhance their therapeutic effect. Computational approaches that could predict therapeutic efficacy and suggest ACP candidates for experimental studies are discussed. Future research prospects in this rapidly expanding area are also offered.

In Model, In Vitro and In Vivo Killing Efficacy of Antitumor Peptide RDP22 on MUG-Mel2, a Patient Derived Cell Line of an Aggressive Melanoma Metastasis

The host defense derived peptide was assessed in different model systems with increasing complexity employing the highly aggressive NRAS mutated melanoma metastases cell line MUG-Mel2. Amongst others, fluorescence microscopy and spectroscopy, as well as cell death studies were applied for liposomal, 2D and 3D in vitro models including tumor spheroids without or within skin models and in vivo mouse xenografts. Summarized, MUG-Mel2 cells were shown to significantly expose the negatively charged lipid phosphatidylserine on their plasma membranes, showing they are successfully targeted by RDP22. The peptide was able to induce cell death in MUG-Mel2 2D and 3D cultures, where it was able to kill tumor cells even inside the core of tumor spheroids or inside a melanoma organotypic model. In vitro studies indicated cell death by apoptosis upon peptide treatment with an LC₅₀ of 8.5 µM and seven-fold specificity for the melanoma cell line MUG-Mel2 over normal dermal fibroblasts. In vivo studies in mice xenografts revealed effective tumor regression upon intratumoral peptide injection, indicated by the strong clearance of pigmented tumor cells and tremendous reduction in tumor size and proliferation, which was determined histologically. The peptide RDP22 has clearly shown high potential against the melanoma cell line MUG-Mel2 in vitro and in vivo.

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.

Diptoindonesin G antagonizes AR signaling and enhances the efficacy of antiandrogen therapy in prostate cancer

BACKGROUND

The androgen receptor (AR) signaling pathway has been well demonstrated to play a crucial role in the development, progression, and drug resistance of prostate cancer. Although the current anti-androgen therapy could significantly benefit prostate cancer patients initially, the efficacy of the single drug usually lasts for a relatively short period, as drug resistance quickly emerges.

METHODS

We have performed an unbiased bioinformatics analysis using the RNA-seq results in 22Rv1 cells to identify the cell response toward Dip G treatment. The RNA-seq results were validated by qRT-PCR. Protein levels were detected by western blot or staining. Cell viability was measured by Aquabluer and colony formation assay.

RESULTS

Here, we identified that Diptoindonesin G (Dip G), a natural extracted compound, could promote the proteasome degradation of AR and polo-like kinase 1 (PLK1) through modulating the activation of CHIP E3 ligase. Administration of Dip G has shown a profound efficiency in the suppression of AR and PLK1, not only in androgen-dependent LNCaP cells but also in castration-resistant and enzalutamide-resistant cells in a CHIP-dependent manner. Through co-targeting the AR signaling, Dip G robustly improved the efficacy of HSP90 inhibitors and enzalutamide in both human prostate cancer cells and in vivo xenograft mouse model.

CONCLUSIONS

Our results revealed that Dip G-mediated AR degradation would be a promising and valuable therapeutic strategy in the clinic.

Antimicrobial Peptides and Cationic Nanoparticles: A Broad-Spectrum Weapon to Fight Multi-Drug Resistance Not Only in Bacteria

In the last few years, antibiotic resistance and, analogously, anticancer drug resistance have increased considerably, becoming one of the main public health problems. For this reason, it is crucial to find therapeutic strategies able to counteract the onset of multi-drug resistance (MDR). In this review, a critical overview of the innovative tools available today to fight MDR is reported. In this direction, the use of membrane-disruptive peptides/peptidomimetics (MDPs), such as antimicrobial peptides (AMPs), has received particular attention, due to their high selectivity and to their limited side effects. Moreover, similarities between bacteria and cancer cells are herein reported and the hypothesis of the possible use of AMPs also in anticancer therapies is discussed. However, it is important to take into account the limitations that could negatively impact clinical application and, in particular, the need for an efficient delivery system. In this regard, the use of nanoparticles (NPs) is proposed as a potential strategy to improve therapy; moreover, among polymeric NPs, cationic ones are emerging as promising tools able to fight the onset of MDR both in bacteria and in cancer cells.

The Influence of Short Motifs on the Anticancer Activity of HB43 Peptide

Despite the remarkable similarity in amino acid composition, many anticancer peptides (ACPs) display significant differences in terms of activity. This strongly suggests that particular relative dispositions of amino acids (motifs) play a role in the interaction with their biological target, which is often the cell membrane. To better verify this hypothesis, we intentionally modify HB43, an ACP active against a wide variety of cancers. Sequence alignment of related ACPs by ADAPTABLE web server highlighted the conserved motifs that could be at the origin of the activity. In this study, we show that changing the order of amino acids in such motifs results in a significant loss of activity against colon and breast cancer cell lines. On the contrary, amino acid substitution in key motifs may reinforce or weaken the activity, even when the alteration does not perturb the amphipathicity of the helix formed by HB43 on liposomes mimicking their surface. NMR and MD simulations with different membrane models (micelles, bicelles, and vesicles) indicate that the activity reflects the insertion capability in cancer-mimicking serine-exposing membranes, supported by the insertion of N-terminal phenylalanine in the FAK motif and the anchoring to the carboxylate of phosphatidylserine by means of arginine side chains.

The Anticancer Activity Conferred by the Mud Crab Antimicrobial Peptide Scyreprocin through Apoptosis and Membrane Disruption

Scyreprocin is an antimicrobial peptide first identified in the mud crab Scylla paramamosain. Herein, we showed that its recombinant product (rScyreprocin) could significantly inhibit the growth of human lung cancer NCI-H460 cells (H460), but showed no cytotoxicity to human lung fibroblasts (HFL1). rScyreprocin was a membrane-active peptide that firstly induced the generation of reactive oxygen species (ROS) in H460, and led to endoplasmic reticulum stress and Ca²⁺ release, which resulted in mitochondrial dysfunction and subsequently activation of caspase-3 cascades, and ultimately led to apoptosis. The comprehensive results indicated that rScyreprocin exerted anticancer activity by disrupting cell membrane and inducing apoptosis. The in vivo efficacy test demonstrated that intratumoral injection of rScyreprocin significantly inhibited the growth of H460 xenografts, which was close to that of the cisplatin (inhibition rate: 69.94% vs. 80.76%). Therefore, rScyreprocin is expected to become a promising candidate for the treatment of lung cancer.

Development of Anticancer Peptides Using Artificial Intelligence and Combinational Therapy for Cancer Therapeutics

Cancer is a group of diseases causing abnormal cell growth, altering the genome, and invading or spreading to other parts of the body. Among therapeutic peptide drugs, anticancer peptides (ACPs) have been considered to target and kill cancer cells because cancer cells have unique characteristics such as a high negative charge and abundance of microvilli in the cell membrane when compared to a normal cell. ACPs have several advantages, such as high specificity, cost-effectiveness, low immunogenicity, minimal toxicity, and high tolerance under normal physiological conditions. However, the development and identification of ACPs are time-consuming and expensive in traditional wet-lab-based approaches. Thus, the application of artificial intelligence on the approaches can save time and reduce the cost to identify candidate ACPs. Recently, machine learning (ML), deep learning (DL), and hybrid learning (ML combined DL) have emerged into the development of ACPs without experimental analysis, owing to advances in computer power and big data from the power system. Additionally, we suggest that combination therapy with classical approaches and ACPs might be one of the impactful approaches to increase the efficiency of cancer therapy.

Integrated Design of a Membrane-Lytic Peptide-Based Intravenous Nanotherapeutic Suppresses Triple-Negative Breast Cancer

Membrane-lytic peptides offer broad synthetic flexibilities and design potential to the arsenal of anticancer therapeutics, which can be limited by cytotoxicity to noncancerous cells and induction of drug resistance via stress-induced mutagenesis. Despite continued research efforts on membrane-perforating peptides for antimicrobial applications, success in anticancer peptide therapeutics remains elusive given the muted distinction between cancerous and normal cell membranes and the challenge of peptide degradation and neutralization upon intravenous delivery. Using triple-negative breast cancer as a model, the authors report the development of a new class of anticancer peptides. Through function-conserving mutations, the authors achieved cancer cell selective membrane perforation, with leads exhibiting a 200-fold selectivity over non-cancerogenic cells and superior cytotoxicity over doxorubicin against breast cancer tumorspheres. Upon continuous exposure to the anticancer peptides at growth-arresting concentrations, cancer cells do not exhibit resistance phenotype, frequently observed under chemotherapeutic treatment. The authors further demonstrate efficient encapsulation of the anticancer peptides in 20 nm polymeric nanocarriers, which possess high tolerability and lead to effective tumor growth inhibition in a mouse model of MDA-MB-231 triple-negative breast cancer. This work demonstrates a multidisciplinary approach for enabling translationally relevant membrane-lytic peptides in oncology, opening up a vast chemical repertoire to the arms race against cancer.

Anti-cancer peptide-based therapeutic strategies in solid tumors

BACKGROUND

Nowadays, conventional medical treatments such as surgery, radiotherapy, and chemotherapy cannot cure all types of cancer. A promising approach to treat solid tumors is the use of tumor-targeting peptides to deliver drugs or active agents selectively.

RESULT

Introducing beneficial therapeutic approaches, such as therapeutic peptides and their varied methods of action against tumor cells, can aid researchers in the discovery of novel peptides for cancer treatment. The biomedical applications of therapeutic peptides are highly interesting. These peptides, owing to their high selectivity, specificity, small dimensions, high biocompatibility, and easy modification, provide good opportunities for targeted drug delivery. In recent years, peptides have shown considerable promise as therapeutics or targeting ligands in cancer research and nanotechnology.

CONCLUSION

 This study reviews a variety of therapeutic peptides and targeting ligands in cancer therapy. Initially, three types of tumor-homing and cell-penetrating peptides (CPPs) are described, and then their applications in breast, glioma, colorectal, and melanoma cancer research are discussed.

Antimicrobial peptides as potential therapeutics for breast cancer

Breast cancer is the most common and deadliest cancer in women worldwide. Although notable advances have been achieved in the treatment of breast cancer, the overall survival rate of metastatic breast cancer patients is still considerably low due to the development of resistance to breast cancer chemotherapeutic agents and the non-optimal specificity of the current generation of cancer medications. Hence, there is a growing interest in the search for alternative therapeutics with novel anticancer mechanisms. Recently, antimicrobial peptides (AMPs) have gained much attention due to their cost-effectiveness, high specificity of action, and robust efficacy. However, there are no clinical data available about their efficacy. This warrants the increasing need for clinical trials to be conducted to assess the efficacy of this new class of drugs. Here, we will focus on the recent progress in the use of AMPs for breast cancer therapy and will highlight their modes of action. Finally, we will discuss the combination of AMP-based therapeutics with other breast cancer therapy strategies, including nanotherapy and chemotherapy, which may provide a potential avenue for overcoming drug resistance.

Anti-metastatic Effects of Cationic KT2 Peptide (a Lysine/Tryptophan-rich Peptide) on Human Melanoma A375.S2 Cells

BACKGROUND/AIM

KT2 is a lysine/tryptophan-rich peptide modified from Crocodylus siamensis Leucrocin I. In this study, we examined the cell toxicity, cellular uptake, anti-migration and anti-invasion activities of KT2 in A375.S2 human melanoma cells.

MATERIALS AND METHODS

A375.S2 cells were treated with KT2 peptide and then we performed MTT assay, study of cellular uptake by a confocal microscope, wound healing assay, transwell migration/invasion assay, and evaluation of the expression of metastasis-associated proteins.

RESULTS

KT2 can be internalized through the plasma membrane and can slightly alter cell morphology, decrease the percentage of viable cells and inhibit cell migration and invasion of A375.S2 cells in a dose-dependent manner. This peptide suppressed MMP-2 activity, as measured by gelatine zymography assay. The protein level of MMP-2 was decreased by KT2. KT2 also down-regulated metastasis pathway-related molecules, including FAK, RhoA, ROCK1, GRB2, SOS-1, p-JNK, p-c-Jun, PI3K, p-AKT (Thr308), p-AKT (Ser473), p-p38, MMP-9, NF-kB, and uPA.

CONCLUSION

These results indicate that KT2 inhibits the migration and invasion of human melanoma cells by decreasing MMP-2 and MMP-9 expression through inhibition of FAK, uPA, MAPK, PI3K/AKT NF-kB, and RhoA-ROCK signalling pathways. These findings suggest that KT2 deserves further investigation as an anti-metastatic agent for human melanoma.

Recent Advances in Therapeutic Peptides for Breast Cancer Treatment

Breast cancer is a heterogeneous malignancy and is the second leading cause of mortality among women around the world. Increasing the resistance to anti-cancer drugs in breast cancer cells persuades researchers to search the novel therapeutic approaches for the treatment of this malignancy. Among the novel methods, therapeutic peptides that target and disrupt tumor cells have been of great interest. Therapeutic peptides are short amino acid monomer chains with high specificity to bind and modulate a protein interaction of interest. Several advantages of peptides, such as specific binding on tumor cells surface, low molecular weight, and low toxicity on normal cells, make the peptides appealing therapeutic agents against solid tumors, particularly breast cancer. Also, the National Institutes of Health (NIH) describes therapeutic peptides as a suitable candidate for the treatment of drug-resistant breast cancer. In this review, we attempt to review the different therapeutic peptides against breast cancer cells that can be used in the treatment and diagnosis of the malignancy. Meanwhile, we presented an overview of peptide vaccines that have been developed for the treatment of breast cancer.

Recombinant protein TRAIL-Mu3 enhances the antitumor effects in pancreatic cancer cells by strengthening the apoptotic signaling pathway

Pancreatic cancer is a highly malignant type of cancer and its treatment remains a major challenge. The novel recombinant protein TNF-related apoptosis-inducing ligand (TRAIL)-Mu3 has been shown to exert stronger tumor inhibitory effects in colon cancer in vitro and in vivo compared with TRAIL. The present study investigated the antitumor effects of TRAIL-Mu3 on pancreatic cancer cells, and the possible mechanisms were further examined. Compared with TRAIL, TRAIL-Mu3 exhibited significantly higher cytotoxic effects on pancreatic cancer cell lines. The inhibitory effect of TRAIL-Mu3 on the viability of PANC-1 cells was shown to be a caspase-dependent process. The affinity of TRAIL-Mu3 to PANC-1 cell membranes was significantly enhanced compared with TRAIL. In addition, TRAIL-Mu3 upregulated death receptor (DR) expression in PANC-1 cells and promoted the redistribution of DR5 in lipid rafts. Western blotting results demonstrated that TRAIL-Mu3 activated the caspase cascade in a faster and more efficient manner compared with TRAIL in PANC-1 cells. Therefore, TRAIL-Mu3 enhanced the antitumor effects in pancreatic cancer cells by strengthening the apoptotic signaling pathway. The present study indicated the potential of TRAIL-Mu3 for the treatment of pancreatic cancer.

Using porphyrins as albumin-binding molecules to enhance antitumor efficacies and reduce systemic toxicities of antimicrobial peptides

Antimicrobial peptides (AMPs) are originally developed for anti-infective treatments. Because of their membrane-lytic property, AMPs have been considered as candidates of antitumor agents for a long time. However, their antitumor applications are mainly hampered by fast renal clearance and high systemic toxicities. This study proposes a strategy aiming at addressing these two issues by conjugating AMPs with porphyrins, which bind to albumin increasing AMPs' resistance against renal clearance and thus enhancing their antitumor efficacies. Porphyrins' photodynamic properties can further augment AMPs' antitumor effects. In addition, circulating with albumin ameliorates AMPs' systemic toxicities, i.e. hemolysis and organ dysfunctions. As an example, we conjugated an AMP, K6L9, with pyropheophorbide-a (PPA) leading to a conjugate of PPA-K6L9. PPA-K6L9 bound to albumin with a K_D value at the sub-micromolar range. Combining computational and experimental approaches, we characterized the molecular interaction of PPA-K6L9 with albumin. Furthermore, PPA-conjugation promoted K6L9' antitumor effects by prolonging its in vivo retention time, and reduced the hemolysis and hepatic injuries, which confirmed our design strategy.

Use of anticancer peptides as an alternative approach for targeted therapy in breast cancer: a review

Breast cancer is the most common cancer in women worldwide. Traditional therapies are expensive and cause severe side effects. Targeted therapy is a powerful method to circumvent the problems of other therapies. It also allows drugs to localize at predefined targets in a selective manner. Currently, there are several monoclonal antibodies which target breast cancer cell surface markers. However, using antibodies has some limitations. In the last two decades, many investigators have discovered peptides that may be useful to target breast cancer cells. In this article, we provide an overview on anti-breast cancer peptides, their sources and biological activities. We further discuss the pros and cons of using anticancer peptides with further emphasis on how to improve their effectiveness in cancer therapy.

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.

Antimicrobial and antitumor activity of peptidomimetics synthesized from amino acids

Thirteen cationic peptidomimetics derived from amino acids bearing an alkyl or ethynylphenyl moiety that mimic the structure of cationic antibacterial peptides were designed and synthesized using a simple coupling reaction of an amino acid with a substituted amine. Antibacterial activities of the resulting peptidomimetics against drug-sensitive bacteria, such as Gram-positive Staphylococcus aureus (S. aureus) and Bacillus subtilis, Gram-negative Escherichia coli (E. coli) and Salmonella enterica, and a drug-resistant bacterium, methicillin-resistant S. aureus (MRSA), were systematically evaluated. Most peptidomimetics show significant broad-spectrum antibacterial activity. A-L-Iso-C₁₂ (isoleucine derivative bearing a dodecyl moiety) show MICs of 2.5 μg/mL against S. aureus and 4 μg/mL against MRSA and A-L-Val-C₁₂ (valine derivative bearing a dodecyl moiety) show MICs of 1.67 μg/mL against E. coli and 8.3 μg/mL against MRSA. A-L-Val-C₁₂ showed low cytotoxicity toward L929 cells in comparison with SGC 7901 cells, indicating tumor-directed killing by peptidomimetics while avoiding toxicity to normal cells. The influences of type of amino acid and substituent, length of substituent, and stereochemistry of amino acids on antibacterial activity and cytotoxicity of peptidomimetics were systematically investigated. The results indicate that this series of cationic peptidomimetics derived from amino acids display antitumor activity and may be useful for treatment of bacterial infections.

Phlogiellus bundokalbo spider venom: cytotoxic fractions against human lung adenocarcinoma (A549) cells

Background

Spider venom is a potential source of pharmacologically important compounds. Previous studies on spider venoms reported the presence of bioactive molecules that possess cell-modulating activities. Despite these claims, sparse scientific evidence is available on the cytotoxic mechanisms in relation to the components of the spider venom. In this study, we aimed to determine the cytotoxic fractions of the spider venom extracted from Phlogiellus bundokalbo and to ascertain the possible mechanism of toxicity towards human lung adenocarcinoma (A549) cells.

Methods

Spider venom was extracted by electrostimulation. Components of the extracted venom were separated by reversed-phase high performance liquid chromatography (RP-HPLC) using a linear gradient of 0.1% trifluoroacetic acid (TFA) in water and 0.1% TFA in 95% acetonitrile (ACN). Cytotoxic activity was evaluated by the MTT assay. Apoptotic or necrotic cell death was assessed by microscopic evaluation in the presence of Hoechst 33342 and Annexin V, Alexa Fluor^TM 488 conjugate fluorescent stains, and caspase activation assay. Phospholipase A₂ (PLA₂) activity of the cytotoxic fractions were also measured.

Results

We observed and isolated six fractions from the venom of P. bundokalbo collected from Aurora, Zamboanga del Sur. Four of these fractions displayed cytotoxic activities. Fractions AT5-1, AT5-3, and AT5-4 were found to be apoptotic while AT5-6, the least polar among the cytotoxic components, was observed to induce necrosis. PLA₂ activity also showed cytotoxicity in all fractions but presented no relationship between specific activity of PLA₂ and cytotoxicity.

Conclusion

The venom of P. bundokalbo spider, an endemic tarantula species in the Philippines, contains components that were able to induce either apoptosis or necrosis in A549 cells.

Antimicrobial Peptides as Anticancer Agents: Functional Properties and Biological Activities

Antimicrobial peptides (AMPs), or host defense peptides, are small cationic or amphipathic molecules produced by prokaryotic and eukaryotic organisms that play a key role in the innate immune defense against viruses, bacteria and fungi. AMPs have either antimicrobial or anticancer activities. Indeed, cationic AMPs are able to disrupt microbial cell membranes by interacting with negatively charged phospholipids. Moreover, several peptides are capable to trigger cytotoxicity of human cancer cells by binding to negatively charged phosphatidylserine moieties which are selectively exposed on the outer surface of cancer cell plasma membranes. In addition, some AMPs, such as LTX-315, have shown to induce release of tumor antigens and potent damage associated molecular patterns by causing alterations in the intracellular organelles of cancer cells. Given the recognized medical need of novel anticancer drugs, AMPs could represent a potential source of effective therapeutic agents, either alone or in combination with other small molecules, in oncology. In this review we summarize and describe the properties and the mode of action of AMPs as well as the strategies to increase their selectivity toward specific cancer cells.

An Anti-Cancer Peptide LVTX-8 Inhibits the Proliferation and Migration of Lung Tumor Cells by Regulating Causal Genes' Expression in p53-Related Pathways

Spider venom has been found to show its anticancer activity in a variety of human malignancies, including lung cancer. In this study, we investigated the anti-cancer peptide toxin LVTX-8, with linear amphipathic alpha-helical conformation, designed and synthesized from the cDNA library of spider Lycosa vittata. Multiple cellular methods, such as CCK-8 assay, flow cytometry, colony formation assay, Transwell invasion and migration assay, were performed to detect peptide-induced cell growth inhibition and anti-metastasis in lung cancer cells. Our results demonstrated that LVTX-8 displayed strong cytotoxicity and anti-metastasis towards lung cancer in vitro. Furthermore, LVTX-8 could suppress the growth and metastasis of lung cancer cells (A549 and H460) in nude mouse models. Transcriptomics, integrated with multiple bioinformatics analysis, suggested that the molecular basis of the LVTX-8-mediated inhibition of cancer cell growth and metastasis manifested in two aspects: Firstly, it could restrain the activity of cancer cell division and migration through the functional pathways, including "p53 hypoxia pathway" and "integrin signaling". Secondly, it could regulate the expression level of apoptotic-related proteins, which may account for programmed apoptosis of cancer cells. Taken together, as an anticancer peptide with high efficiency and acceptable specificity, LVTX-8 may become a potential precursor of a therapeutic agent for lung cancer in the future.

A Uniquely Modified DKL-based Peptide Probe for Positron Emission Tomography Imaging

Peptides containing the asparagine-glycine-arginine (NGR) motif can target the tumor neovascular biomarker CD13/aminopeptidase N receptor. D-K6L9 is a tumor-selective anti-cancer peptide. To improve the capacity of NGR peptides to target tumors, we joined the NGR and D-K6L9 peptides to form NKL. Next, we linked 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) to NKL and labeled it with gallium 68 (68Ga, t1/2 = 67.7 min) to form 68Ga-DOTA-NKL. This novel probe was characterized in vitro. 68Ga-DOTA-NKL was stable in phosphate buffered saline at room temperature and in human serum at 37°C. We determined that the uptake rate of 68Ga-DOTA-NKL in CD13 receptor-positive 22Rv1 tumor cells was 3.15% ± 0.04 after 2 h, and tested 68Ga-DOTA-NKL using positron emission tomography (PET)/computed tomography imaging in vivo. MicroPET imaging results revealed that 22Rv1 tumor uptake of 68Ga-DOTA-NKL was 8.69 ± 0.20, 6.61 ± 0.22, 3.85 ± 0.06, and 1.41 ± 0.23 percentage injected dose per gram of tissue (%ID/g) at 0.5, 1, 2, and 3 h postinjection (pi), respectively. The tumor-to-background contrast in the subcutaneous human prostate cancer 22Rv1 mouse model was 9.97 ± 1.90. The 68Ga-DOTA-NKL probe has combined tumor-targeting and tumor-selective properties, and may be used to diagnose CD13-positive tumors.

ACPred: A Computational Tool for the Prediction and Analysis of Anticancer Peptides

Anticancer peptides (ACPs) have emerged as a new class of therapeutic agent for cancer treatment due to their lower toxicity as well as greater efficacy, selectivity and specificity when compared to conventional small molecule drugs. However, the experimental identification of ACPs still remains a time-consuming and expensive endeavor. Therefore, it is desirable to develop and improve upon existing computational models for predicting and characterizing ACPs. In this study, we present a bioinformatics tool called the ACPred, which is an interpretable tool for the prediction and characterization of the anticancer activities of peptides. ACPred was developed by utilizing powerful machine learning models (support vector machine and random forest) and various classes of peptide features. It was observed by a jackknife cross-validation test that ACPred can achieve an overall accuracy of 95.61% in identifying ACPs. In addition, analysis revealed the following distinguishing characteristics that ACPs possess: (i) hydrophobic residue enhances the cationic properties of α-helical ACPs resulting in better cell penetration; (ii) the amphipathic nature of the α-helical structure plays a crucial role in its mechanism of cytotoxicity; and (iii) the formation of disulfide bridges on β-sheets is vital for structural maintenance which correlates with its ability to kill cancer cells. Finally, for the convenience of experimental scientists, the ACPred web server was established and made freely available online.

Improving Selectivity, Proteolytic Stability, and Antitumor Activity of Hymenochirin-1B: A Novel Glycosylated Staple Strategy

As a host defense peptide, hymenochirin-1B has attracted increasing attention for its strong cytotoxic activities. However, its poor selectivity and proteolytic stability remain major obstacles for clinical application. To solve these problems, we designed and synthesized a series of peptide analogues of hymenochirin-1B based on cationic residue substitution and stapling combined with a glycosylation strategy. Some analogues showed improvement not only in selectivity and proteolytic stability but also in antitumor activity. Among them, the glycosylated stapled peptide H-58 was identified as the most potential antitumor peptide. Flow cytometry and a competitive binding assay revealed that H-58 displayed significant antitumor selectivity. Confocal microscopy and nuclear staining with Hoechst dye demonstrated that H-58 entered the nucleus and caused DNA damage. In summary, the strategy of glycosylated stapled peptides is a promising approach for improving the antitumor selectivity, proteolytic stability, and antitumor activity of hymenochirin-1B, which can be used for other bioactive peptide modifications.

Host defense peptide Hymenochirin-1B induces lung cancer cell apoptosis and cell cycle arrest through the mitochondrial pathway

The antineoplastic activity of host defense peptide Hymenochirin-1B, has been extensively studied. However, the mechanism still remains unknown. In this study, linear peptide, Hymenochirin-1B, was synthesized via solid-phase peptide synthesis and evaluated for its anticancer efficacy. We found Hymenochirin-1B induced lung cancer cell apoptosis and cell cycle arrest at the G0/G1 phase. Moreover, Hymenochirin-1B could enter the cells and colocalized with mitochondria. Furthermore, decrease of mitochondrial membrane potential, increase of reactive oxygen species and the expression of apoptosis-associated protein (Bax/Bcl-2 ratio and activated Caspase-3) were observed in NCI-H1299 and A549 cells after Hymenochirin-1B treatment, suggesting that Hymenochirin-1B induced apoptosis via mitochondrial pathway. Our results provide new insights on the anticancer mechanism of Hymenochirin-1B, which may contribute to its further development into an antineoplastic drug in the future.

Unraveling the bioactivity of anticancer peptides as deduced from machine learning

Cancer imposes a global health burden as it represents one of the leading causes of morbidity and mortality while also giving rise to significant economic burden owing to the associated expenditures for its monitoring and treatment. In spite of advancements in cancer therapy, the low success rate and recurrence of tumor has necessitated the ongoing search for new therapeutic agents. Aside from drugs based on small molecules and protein-based biopharmaceuticals, there has been an intense effort geared towards the development of peptide-based therapeutics owing to its favorable and intrinsic properties of being relatively small, highly selective, potent, safe and low in production costs. In spite of these advantages, there are several inherent weaknesses that are in need of attention in the design and development of therapeutic peptides. An abundance of data on bioactive and therapeutic peptides have been accumulated over the years and the burgeoning area of artificial intelligence has set the stage for the lucrative utilization of machine learning to make sense of these large and high-dimensional data. This review summarizes the current state-of-the-art on the application of machine learning for studying the bioactivity of anticancer peptides along with future outlook of the field. Data and R codes used in the analysis herein are available on GitHub at https://github.com/Shoombuatong2527/anticancer-peptides-review.

Antimicrobial peptides with selective antitumor mechanisms: prospect for anticancer applications

In the last several decades, there have been significant advances in anticancer therapy. However, the development of resistance to cancer drugs and the lack of specificity related to actively dividing cells leading to toxic side effects have undermined these achievements. As a result, there is considerable interest in alternative drugs with novel antitumor mechanisms. In addition to the recent approach using immunotherapy, an effective but much cheaper therapeutic option of pharmaceutical drugs would still provide the best choice for cancer patients as the first line treatment. Ribosomally synthesized cationic antimicrobial peptides (AMPs) or host defense peptides (HDP) display broad-spectrum activity against bacteria based on electrostatic interactions with negatively charged lipids on the bacterial surface. Because of increased proportions of phosphatidylserine (negatively charged) on the surface of cancer cells compared to normal cells, cationic amphipathic peptides could be an effective source of anticancer agents that are both selective and refractory to current resistance mechanisms. We reviewed herein the prospect for AMP application to cancer treatment, with a focus on modes of action of cationic AMPs.

PaDef defensin from avocado (Persea americana var. drymifolia) is cytotoxic to K562 chronic myeloid leukemia cells through extrinsic apoptosis

Plant defensins, a group of antimicrobial peptides, show selective cytotoxicity toward cancer cells. However, their mechanisms of action remain poorly understood. Here, we evaluated the cytotoxicity of PaDef defensin from avocado (Persea americana var. drymifolia) on K562 chronic myeloid leukemia cells and analyzed the pathway involved in the induction of cell death. The defensin PaDef was not cytotoxic against human PBMCs; however, it was cytotoxic for K562 cell line (IC₅₀ = 97.3 μg/ml) activating apoptosis at 12 h. PaDef did not affect the mitochondrial membrane potential (ΔΨm), neither the transmembranal potential or the release of intracellular calcium. Also, PaDef induced gene expression of caspase 8 (∼2 fold), TNF-α (∼4 fold) and TNFR1 (∼10 fold). In addition, the activation of caspase 8 was detected at 24 h, whereas caspase 9 activity was not modified, suggesting that the extrinsic apoptosis pathway could be activated. In conclusion, PaDef induces apoptosis on K562 cells, which is related to the activation of caspase 8 and involves the participation of TNF-α, which is a novel property for a plant defensin.

Molecular mechanisms of an antimicrobial peptide piscidin (Lc-pis) in a parasitic protozoan, Cryptocaryon irritans

Background

Cryptocaryon irritans is an obligate parasitic ciliate protozoan that can infect various commercially important mariculture fish species and cause high lethality and economic loss. Current methods of controlling this parasite with chemicals or antibiotics are widely considered to be environmentally harmful. Piscidins with broad spectrum antibacterial, antifungal and antiviral activities were found to have potent activity against C. irritans. Little, however, has been understood about the killing mechanisms of piscidins in parasites.

Results

In total, 57.12, 50.44, 55.86 and 47.87 million raw reads were generated from untreated theront and trophont, and piscidin (Lc-pis) treated theront and trophont libraries, respectively. After de novo assembly, 966,609 unigenes were generated with an average length of 420 bp: among these, 618,629 unigenes showed identity with sequences in one or more databases, with some showing to be significantly manipulated by Lc-pis treatment. The species classification showed that more than 25.8% unigenes from trophonts were homologous to the large yellow croaker (Larimichthys crocea) and less than 3.8% unigenes from theronts were matched. The homologous unigenes demonstrated that the tissue from host could exist in trophonts and might be transported to parasite via vesicular transports. Our analysis showed that regulatory transcripts were involved in vesicular trafficking. Among transcripts induced by Lc-pis, most genes up-regulated in treated and untreated theronts were involved in cell migration and apoptosis related pathways. Few transcripts were found to be down-regulated in treated and untreated trophonts related to cell structure and migration after treatment.

Conclusions

This is the first transcriptome analysis of C. irritans exposed to Lc-pis, which enhanced the genomic resources and provided novel insights into molecular mechanisms of ciliates treated by cationic antimicrobial peptide. Our comprehensive transcriptome analysis can facilitate the identification of potential drug targets and vaccines candidates for controlling this devastating fish pathogen.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4565-5) contains supplementary material, which is available to authorized users.

MUC1 aptamer-targeted DNA micelles for dual tumor therapy using doxorubicin and KLA peptide

Targeted delivery of DNA nanoparticles is a promising approach in cancer therapy. Using aptamers, target specific delivery of DNA nanoparticles can be achieved. Further, aptamers can indirectly improve drug encapsulation efficiency of DNA nanoparticles for drugs intercalated within nucleic acid base pairs. Using DNA blocks, a micellar hybrid nanoparticle was prepared for the targeted co-delivery of doxorubicin and a pro-apoptotic peptide, KLA to tumor cells. Results demonstrated that anti-MUC1 aptamer could specifically deliver the synthesized DNA micelle into MCF-7 cells by improving its cellular uptake. Additionally, co-delivery of doxorubicin and KLA could significantly enhance the therapeutic efficacy of the construct resulting in reduction of required dose of doxorubicin that is a pivotal point in reducing chemotherapeutics side effects. Moreover, DOX-KLA-anti-MUC1-micelle remarkably inhibited tumor growth of tumor-bearing mice when compared with free drug. DOX-KLA-anti-MUC1-micelle also reduced toxic effect of free doxorubicin as determined by percent of body weight loss and survival rate in vivo.

Novel cell-penetrating-amyloid peptide conjugates preferentially kill cancer cells

The goal of this study was to develop a peptide which could use the toxic effects of amyloid, a substance which is the hallmark of over 25 known human diseases, to selectively kill cancer cells. Here we demonstrate that two separate amyloid-forming hexapeptides, one from the microtubule associated protein Tau involved in formation of paired helical filaments of Alzheimer's disease, and the other an amyloid forming sequence from apolipoprotein A1, when conjugated to a cell penetrating peptide (CPP) sequence, form toxic oligomers which are stable for up to 14 h and able to enter cells by a combination of endocytosis and transduction. The amyloid peptide conjugates showed selective cytotoxicity to breast cancer, neuroblastoma and cervical cancer cells in culture compared to normal cells. Fluorescence imaging experiments showed the CPP-amyloid peptide oligomers formed intracellular fibrous amyloid, visible in the endosomes/lysosomes, cytosol and nucleus with thioflavin S (ThS) staining. Further experiments with rhodamine-conjugated Dextran, propidium iodide (PI), and acridine orange (AO) suggested the mechanism of cell death was the permeability of the lysosomal membrane brought about by the formation of amyloid pores. Cytotoxicity could be abrogated by inhibitors of lysosomal hydrolases, consistent with a model where lysosomal hydrolases leak into the cytosol and induce cytotoxicity in subsequent downstream steps. Taken together, our data suggest that CPP-amyloid peptide conjugates show potential as a new class of anti-cancer peptides (ACPs).

Enhanced efficacy of the engineered antimicrobial peptide WLBU2 via direct airway delivery in a murine model of Pseudomonas aeruginosa pneumonia

OBJECTIVES

Pseudomonas aeruginosa is a common cause of pneumonia in patients with cystic fibrosis with the property to generate multidrug resistance against clinically used antibiotics. Antimicrobial peptides (AMPs) are a diverse group of effector molecules of the innate immune system that protect the host against pathogens. However, the lack of activity in common biological matrices has hampered efforts towards clinical development. In this study, we evaluated the therapeutic potential of the engineered AMP WLBU2 via direct airway delivery in a murine model of P. aeruginosa infection.

METHODS

The human AMPs LL37 and WLBU2 were compared for (i) antibiofilm activity using P. aeruginosa on polarized human bronchial epithelial cells, and (ii) efficacy in P. aeruginosa pneumonia in mice using intratracheal instillation of bacteria and AMPs.

RESULTS

WLBU2 (16 μM) prevents biofilm formation by up to 3-log compared with 1-log reduction by LL37. With a single dose of 1 μg (0.05 mg/kg) delivered intratracheally, the initial effect of LL37 was moderate and transitory, as bacterial load and inflammatory cytokines increased at 24 h with observed signs of disease such as lethargy and hypothermia, consistent with moribund state requiring euthanasia. In sharp contrast, WLBU2 reduced bacterial burden (by 2 logs) and bacteria-induced inflammation (leucocytic infiltrates, cytokine and chemokine gene expression) at 6 h and 24 h post-exposure, with no observed signs of disease or host toxicity.

CONCLUSION

These promising results now establish a much lower minimum therapeutic dose of WLBU2 (a net gain of 80-fold) compared with the previously reported 4 mg/kg systemic minimum therapeutic dose, with significant implications for clinical development.

Amino acid or peptide conjugates of acridine/acridone and quinoline/quinolone-containing drugs. A critical examination of their clinical effectiveness within a twenty-year timeframe in antitumor chemotherapy and treatment of infectious diseases

Acridines/acridones, quinolines/quinolones (chromophores) and their derivatives constitute extremely important family of compounds in current medicine. Great significance of the compounds is connected with antimicrobial and antitumor activities. Combining these features together in one drug seems to be long-term benefit, especially in oncology therapy. The attractiveness of the chromophore drugs is still enhanced by elimination their toxicity and improvement not only selectivity, specificity but also bioavailability. The best results are reached by conjugation to natural peptides. This paper highlights significant advance in the study of amino acid or peptide chromophore conjugates that provide highly encouraging data for novel drug development. The structures and clinical significance of amino acid or peptide chromophore conjugates are widely discussed.

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.

Intramembrane attenuation of the TLR4-TLR6 dimer impairs receptor assembly and reduces microglia-mediated neurodegeneration

Recently, a single study revealed a new complex composed of Toll-like receptor 4 (TLR4), TLR6, and CD36 induced by fibrillary Aβ peptides, the hallmark of Alzheimer's disease. Unlike TLRs located on the plasma membrane that dimerize on the membrane after ligand binding to their extracellular domain, the TLR4-TLR6-CD36 complex assembly has been suggested to be induced by intracellular signals from CD36, similar to integrin inside-out signaling. However, the assembly site of TLR4-TLR6-CD36 and the domains participating in Aβ-induced signaling is still unknown. By interfering with TLR4-TLR6 dimerization using a TLR4-derived peptide, we show that receptor assembly is abrogated within the plasma membrane. Furthermore, we reveal that the transmembrane domains of TLR4 and TLR6 have an essential role in receptor dimerization and activation. Inhibition of TLR4-TLR6 assembly was associated with reduced secretion of proinflammatory mediators from microglia cells, ultimately rescuing neurons from death. Our findings support TLR4-TLR6 dimerization induced by Aβ. Moreover, we shed new light on TLR4-TLR6 assembly and localization and show the potential of inhibiting TLR4-TLR6 dimerization as a treatment of Alzheimer's disease.

Systemic Delivery of Tumor-Targeted Bax-Derived Membrane-Active Peptides for the Treatment of Melanoma Tumors in a Humanized SCID Mouse Model

Melanoma is a highly metastatic and deadly form of cancer. Invasive melanoma cells overexpress integrin α_vβ₃, which is a well-known target for Arg-Gly-Asp-based (RGD) peptides. We developed a sophisticated method to synthetize milligram amounts of a targeted vector that allows the RGD-mediated targeting, internalization, and release of a mitochondria-disruptive peptide derived from the pro-apoptotic Bax protein. We found that 2.5 μM Bax[109-127] was sufficient to destabilize the mitochondria in ten different tumor cell lines, even in the presence of the anti-apoptotic Bcl2 protein, which is often involved in tumor resistance. This pore-forming peptide displayed antitumor activity when it was covalently linked by a disulfide bridge to the tetrameric RAFT-c[RGD]₄-platform and after intravenous injection in a human melanoma tumor model established in humanized immuno-competent mice. In addition to its direct toxic effect, treatment with this combination induced the release of the immuno-stimulating factor monocyte chimoattractant protein 1 (MCP1) in the blood and a decrease in the level of the pro-angiogenic factor FGF2. Our novel multifunctional, apoptosis-inducing agent could be further customized and assayed for potential use in tumor-targeted therapy.