Membrane-active host defense peptides--challenges and perspectives for the development of novel anticancer drugs

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.

ACP-PDAFF: Pretrained model and dual-channel attentional feature fusion for anticancer peptides prediction

Anticancer peptides(ACPs) have attracted significant interest as a novel method of treating cancer due to their ability to selectively kill cancer cells without damaging normal cells. Many artificial intelligence-based methods have demonstrated impressive performance in predicting ACPs. Nevertheless, the limitations of existing methods in feature engineering include handcrafted features driven by prior knowledge, insufficient feature extraction, and inefficient feature fusion. In this study, we propose a model based on a pretrained model, and dual-channel attentional feature fusion(DAFF), called ACP-PDAFF. Firstly, to reduce the heavy dependence on expert knowledge-based handcrafted features, binary profile features (BPF) and physicochemical properties features(PCPF) are used as inputs to the transformer model. Secondly, aimed at learning more diverse feature informations of ACPs, a pretrained model ProtBert is utilized. Thirdly, for better fusion of different feature channels, DAFF is employed. Finally, to evaluate the performance of the model, we compare it with other methods on five benchmark datasets, including ACP-Mixed-80 dataset, Main and Alternate datasets of AntiCP 2.0, LEE and Independet dataset, and ACPred-Fuse dataset. And the accuracies obtained by ACP-PDAFF are 0.86, 0.80, 0.94, 0.97 and 0.95 on five datasets, respectively, higher than existing methods by 1% to 12%. Therefore, by learning rich feature informations and effectively fusing different feature channels, ACD-PDAFF achieves outstanding performance. Our code and the datasets are available at https://github.com/wongsing/ACP-PDAFF.

Investigation of cytotoxic effect and action mechanism of a synthetic peptide derivative of rabbit cathelicidin against MDA-MB-231 breast cancer cell line

Antimicrobial peptides (AMPs) have sparked significant interest as potential anti-cancer agents, thereby becoming a focal point in pursuing novel cancer-fighting strategies. These peptides possess distinctive properties, underscoring the importance of developing more potent and selectively targeted versions with diverse mechanisms of action against human cancer cells. Such advancements would offer notable advantages compared to existing cancer therapies. This research aimed to examine the toxicity and selectivity of the nrCap18 peptide in both cancer and normal cell lines. Furthermore, the rate of cellular death was assessed using apoptosis and acridine orange/ethidium bromide (AO/EB) double staining at three distinct incubation times. Additionally, the impact of this peptide on the cancer cell cycle and migration was evaluated, and ultimately, the expression of cyclin-dependent kinase 4/6 (CDK4/6) genes was investigated. The results obtained from the study demonstrated significant toxicity and selectivity in cancer cells compared to normal cells. Moreover, a strong progressive increase in cell death was observed over time. Furthermore, the peptide exhibited the ability to halt the progression of cancer cells in the G1 phase of the cell cycle and impede their migration by suppressing the expression of CDK4/6 genes.

Enzyme-responsive oncolytic polypeptide for tumor therapy

Host defense peptide-mimicking cationic oncolytic polymers have attracted increasing attention for cancer treatment in recent years. However, polymers with large amounts of positive charge may cause rapid clearance and severe off-target toxicity. To facilitate in vivo application, an alkaline phosphatase (ALP)-responsive oncolytic polypeptide precursor (C12-PLL/PA) has been reported in this work. C12-PLL/PA could be hydrolyzed into the active form of the oncolytic polypeptide (C12-PLL) by the extracellular alkaline phosphatase within solid tumors, thereby resulting in the conversion of the negative charge to positive charge and restoring its membrane-lytic activity. Detailed mechanistic studies showed that C12-PLL/PA could effectively destroy cancer cell membranes and subsequently result in rapid necrosis of cancer cells. More importantly, C12-PLL/PA significantly inhibited the tumor growth in the 4T1 orthotopic breast tumor model with negligible side effects. In summary, these findings demonstrated that the shielding of the amino groups with phosphate groups represents a secure and effective strategy to develop cationic oncolytic polypeptide, which represents a valuable reference for the design of enzyme-activated oncolytic polymers. STATEMENT OF SIGNIFICANCE: Recently, there has been a growing interest in fabricating host defense peptide-mimicking cationic oncolytic polymers for cancer therapy. However, there remain concerns about the tumor selectivity and off-target toxicity of these cationic polymers. In this study, an alkaline phosphatase-responsive oncolytic polypeptide precursor (C12-PLL/PA) has been developed to selectively target cancer cells while sparing normal cells. Mechanistic investigations demonstrated that C12-PLL/PA effectively disrupted cancer cell membranes, leading to rapid necrosis. Both in vitro and in vivo experiments showed promising anticancer activity and reliable safety of C12-PLL/PA. The findings suggest that this synthetic enzyme-responsive polypeptide holds potential as a tumor-specific oncolytic polymer, paving the way for future applications in cancer therapy.

Design of Highly Selective Zn-Coordinated Polyampholyte for Cancer Treatment and Inhibition of Tumor Metastasis

Developing anticancer agents with negligible cytotoxicity against normal cells while mitigating multidrug resistance and metastasis is challenging. Previously reported cationic polymers have effectively eradicated cancers but are clinically unsuitable due to their limited selectivity. Herein, a series of poly(l-lysine)- and nicotinic acid-based polymers were synthesized using varying amounts of dodecylsuccinic anhydride. Zn-coordinating polymers concealed their cationic charge and enhanced selectivity. These Zn-bound polymers were highly effective against liver and colon cancer cells (HepG2 and Colon 26, respectively) and prevented cancer cell migration. They also displayed potent anticancer activity against drug-resistant cell lines (COR-L23/R): their cationic structure facilitated cancer cell membrane disruption. Compared to these polymers, doxorubicin was less selective and less efficacious against drug-resistant cell lines and was unable to prevent cell migration. These polymers are potential cancer treatment agents, offering a promising solution for mitigating drug resistance and tumor metastasis and representing a novel approach to designing cancer therapeutics.

Antimicrobial and antitumor properties of anuran peptide temporin-SHf induce apoptosis in A549 lung cancer cells

Temporin-SHf is a linear, ultra-short, hydrophobic, α-helix, and phe-rich cationic antimicrobial peptide. The antitumor activities and mechanism of temporin-SHf-induced cancer cell death are unknown. The temporin-SHf was synthesized by solid-phase Fmoc chemistry and antimicrobial and antitumor activities were investigated. Temporin-SHf was microbiocidal, non-hemolytic, and cytotoxic to human cancer cells but not to non-tumorigenic cells. It affected the cancer cells' lysosomal integrity and caused cell membrane damage. The temporin-SHf inhibited A549 cancer cell proliferation and migration. It is anti-angiogenic and causes cancer cell death through apoptosis. The molecular mechanism of action of temporin-SHf confirmed that it kills cancer cells by triggering caspase-dependent apoptosis through an intrinsic mitochondrial pathway. Owing to its short length and broad spectrum of antitumor activity, temporin-SHf is a promising candidate for developing a new class of anticancer drugs.

Recalculating the Route: Repositioning Antimicrobial Peptides for Cancer Treatment

Resistance to antimicrobial drugs has been considered a public health problem. Likewise, the increasing resistance of cancer cells to drugs currently used in therapy has also become a problem. Therefore, the research and development of synthetic peptides bring a new perspective on the emergence of new drugs for treating this resistance since bioinformatics provides a means to optimize these molecules and save time and costs in research. Peptides have several mechanisms of action, such as forming pores on the cell membrane and inhibiting protein synthesis. Some studies report the use of antimicrobial peptides with the potential for action against cancer cells, suggesting a repositioning of antimicrobial peptides to fight back cancer resistance. There is an alteration in the microenvironment, making its net charge negative for the survival and growth of cancer cells. The changes in glycoproteins favor the membrane to have a more negative charge, favoring the interaction between the cells and the peptide, thus making possible the repositioning of these antimicrobial peptides against cancer. Here, we will discuss the mechanism of action, targets and effects of peptides, comparison between microbial and cancer cells, and proteomic changes caused by the interaction of peptides and cells.

Peptidic Compound as DNA Binding Agent: In Silico Fragment-based Design, Machine Learning, Molecular Modeling, Synthesis, and DNA Binding Evaluation

BACKGROUND

Cancer remains a global burden, with increasing mortality rates. Current cancer treatments involve controlling the transcription of malignant DNA genes, either directly or indirectly. DNA exhibits various structural forms, including the G-quadruplex (G4), a secondary structure in guanine-rich regions. G4 plays a crucial role in cellular processes by regulating gene expression and telomerase function. Researchers have recently identified G4-stabilizing binding agents as promising anti-cancer compounds. Additionally, peptides have emerged as effective anticancer pharmaceuticals due to their ability to form multiple hydrogen bonds, electrostatic interactions, and van der Waals forces. These properties enable peptides to bind to specific areas of DNA chains selectively. However, despite these advancements, designing G4-binding peptides remains challenging due to a lack of comprehensive information.

OBJECTIVE

In our present study, we employed an in silico fragment-based approach to design G4- binding peptides. This innovative method combines machine learning classification, molecular docking, and dynamics simulation.

METHODS

AutoDock Vina and Gromacs performed molecular docking and MD simulation, respectively. The machine learning algorithm was implemented by Scikit-learn. Peptide synthesis was performed using the SPPS method. The DNA binding affinity was measured by applying spectrophotometric titration.

RESULTS

As a result of this approach, we identified a high-scoring peptide (p10; sequence: YWRWR). The association constant (Ka) between p10 and the ctDNA double helix chain was 4.45 × 105 M-1. Molecular modeling studies revealed that p10 could form a stable complex with the G4 surface.

CONCLUSION

The obtained Ka value of 4.45 × 105 M-1 indicates favorable interactions. Our findings highlight the role of machine learning and molecular modeling approaches in designing new G4-binding peptides. Further research in this field could lead to targeted treatments that exploit the unique properties of G4 structures.

Nano-immunomodulators: prospective applications to combat drug resistant bacterial infections and related complications

Antimicrobial resistance (AMR) is a growing problem in our healthcare sector, it can make infections more difficult and expensive to treat and lead to treatment failure and increased risk of death. Currently, at least 700,000 people worldwide die each year from AMR. Alternative methods for mitigating drug-resistant bacterial infections are desperately needed because of the unacceptably low rate of conventional antibiotic discovery. Therefore, the implementation of various therapeutic strategies is necessary to deal with drug-resistant bacteria and immunomodulation is one of them which is highly encouraged through various studies. Immunomodulators are different biological or synthetic substances that possess the capability of inducing, suppressing, or overall modulating the innate and adaptive immune system. Some phytochemicals, including flavonoids, glycosides, polysaccharides, terpenoids, essential oils, peptides, synthetic molecules, and synthetic biomaterials, can play a crucial role in the fight against bacterial infections directly or indirectly by enhancing the activity of existing antibiotics or by boosting immunity. Nanotechnology can be used to modulate immune responses through various fabrication methods and strategies of design and for drug formulation by encapsulating potential compounds/molecules in the form of nanoparticles and by surface modification or capping of nanomaterials. This approach can improve drug solubility, stability, and bioavailability, reduce toxicity, and help to increase the effectiveness of drugs against resistant microorganisms. This review aims to provide current developments in the field of immunomodulators of different origins that can be combined with nanotechnology and exploited as potential future drugs or adjuvants to fight drug-resistant bacterial pathogens.

Synthetic lipo-polylysine with anti-cancer activity

Development of novel therapeutic agents that possess different anticancer mechanisms from the traditional antitumor drugs is highly attractive as no medication can cure all types of cancers. Herein, we report a rational design of antitumor lipo-polylysine polymers as synthetic mimics of biosynthetic lipopeptide surfactants featuring antimicrobial or cytotoxic activities for cancer therapy. The optimal polymer shows a wide range of anticancer activities against multiple cancer cells, including highly metastatic and drug-resistant ones, but low toxicity to normal cells. Mechanism studies show that the optimal polymer can interact with the membrane of cancer cells and induce cell necrosis by triggering cell membrane perforation, which is different from the therapeutic mechanisms of traditional anticancer drugs. In vivo studies imply that the optimal polymer efficiently inhibits tumor growth without causing obvious side effects on a C26 graft tumor model. Overall, the lipopeptide-mimicking lipo-polylysine with the advantages of easy synthesis and low cost provides a new anticancer strategy with high efficacy and biocompatibility.

In vitro efficacy of different PEGylation designs on cathelicidin-like peptide with high antibacterial and antifungal activity

Recent reports on antibiotic resistance have highlighted the need to reduce the impact of this global health issue through urgent prevention and control. The World Health Organization currently considers antibiotic resistance as one of the most dangerous threats to global health. Therefore, Antimicrobial peptides (AMPs) are promising for the development of novel antibiotic molecules due to their high antimicrobial effects, non-inducing antimicrobial resistance (AMR) properties, and broad spectrum. Hence, in this study, we developed novel antimicrobial peptide/polymer conjugates to reduce the adverse effects of TN6 (RLLRLLLRLLR) peptide. We demonstrate how our constructs function in vitro in terms of antimicrobial activity, hemolytic activity, cytotoxicity, and protease resistance. Our findings show that our molecules are effective against different types of microorganisms such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant S. aureus, vancomycin-resistant Enteroccus faecium, and Candida albicans, which are known to be pathogenic and antibiotic-resistant. Our constructs generally showed low cytotoxicity relative to the peptide in HaCaT and 3T3 cells. Especially these structures are very successful in terms of hemotoxicity. In the bacteremia model with S. aureus, the naked peptide (TN6) was hemotoxic even at 1 µg/mL, while the hemotoxicity of the conjugates was considerably lower than the peptide. Remarkably in this model, the hemolytic activity of PepC-PEG-pepC conjugate decreased 15-fold from 2.36 to 31.12 µg/mL compared to the bacteria-free 60-min treatment. This is proof that in the case of bacteremia and sepsis, the conjugates specifically direct to bacterial cell membranes rather than red blood cells. In addition, the PepC-PEG-pepC conjugate is resistant to plasma proteases. Moreover, morphological and intracellular damage of the peptide/conjugates to Escherichia coli are demonstrated in SEM and TEM images. These results suggest our molecules can be considered potential next-generation broad-spectrum antibiotic molecule/drug candidates that might be used in clinical cases such as bacteremia and sepsis.

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

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

Non-natural amino acids into LfcinB-derived peptides: effect in their (i) proteolytic degradation and (ii) cytotoxic activity against cancer cells

The dimeric peptide ²⁶[F]: (RRWQWRFKKLG)₂-K-Ahx has exhibited a potent cytotoxic effect against breast cancer cell lines, with position 26 (F) being the most relevant for anti-cancer activity. In this investigation, six analogues of the ²⁶[F] peptide were synthesized in which the 26th position was replaced by non-natural hydrophobic amino acids, finding that some modifications increased the resistance to proteolytic degradation exerted by trypsin or pepsin. Additionally, these modifications increased the cytotoxic effect against breast cancer cells and generated cell death mediated by apoptosis pathways, activating caspases 8 and 9, and did not compromise the integrity of the cytoplasmic membrane. Finally, it was found that the modified peptides have a broad spectrum of action, since they also have a cytotoxic effect against the HeLa human cervical cancer cell line. Peptide ²⁶[F] was inoculated in mice by ip administration and the lethal dose 50 (LD₅₀) was between 70 and 140 mg kg^-1. While for the ²⁶[1-Nal]: (RRWQWR-1-Nal-KKLG)₂-K-Ahx peptide, a dose-response test was performed, and the survival rate was 100%. These results suggested that these peptides are safe in this animal model and could be considered as promissory to develop a treatment against breast cancer.

Targeting Transcriptional CDKs 7, 8, and 9 with Anilinopyrimidine Derivatives as Anticancer Agents: Design, Synthesis, Biological Evaluation and In Silico Studies

Cyclin-dependent kinases (CDKs) are promising targets in chemotherapy. In this study, we report a series of 2-anilinopyrimidine derivatives with CDK inhibitory activity. Twenty-one compounds were synthesized and their CDK inhibitory and cytotoxic activities were evaluated. The representative compounds demonstrate potent antiproliferative activities toward different solid cancer cell lines and provide a promising strategy for the treatment of malignant tumors. Compound 5f was the most potent CDK7 inhibitor (IC₅₀ = 0.479 µM), compound 5d was the most potent CDK8 inhibitor (IC₅₀ = 0.716 µM), and compound 5b was the most potent CDK9 inhibitor (IC₅₀ = 0.059 µM). All the compounds satisfied the Lipinski's rule of five (molecular weight < 500 Da, number of hydrogen bond acceptors <10, and octanol-water partition coefficient and hydrogen bond donor values below 5). Compound 5j is a good candidate for lead optimization because it has a non-hydrogen atom (N) of 23, an acceptable ligand efficiency value of 0.38673, and an acceptable ligand lipophilic efficiency value of 5.5526. The synthesized anilinopyrimidine derivatives have potential as anticancer agents.

Poly(l-Ornithine)-Based Polymeric Micelles as pH-Responsive Macromolecular Anticancer Agents

Anticancer peptides and polymers represent an emerging field of tumor treatment and can physically interact with tumor cells to address the problem of multidrug resistance. In the present study, poly(l-ornithine)-b-poly(l-phenylalanine) (PLO-b-PLF) block copolypeptides were prepared and evaluated as macromolecular anticancer agents. Amphiphilic PLO-b-PLF self-assembles into nanosized polymeric micelles in aqueous solution. Cationic PLO-b-PLF micelles interact steadily with the negatively charged surfaces of cancer cells via electrostatic interactions and kill the cancer cells via membrane lysis. To alleviate the cytotoxicity of PLO-b-PLF, 1,2-dicarboxylic-cyclohexene anhydride (DCA) was anchored to the side chains of PLO via an acid-labile β-amide bond to fabricate PLO(DCA)-b-PLF. Anionic PLO(DCA)-b-PLF showed negligible hemolysis and cytotoxicity under neutral physiological conditions but recovered cytotoxicity (anticancer activity) upon charge reversal in the weakly acidic microenvironment of the tumor. PLO-based polypeptides might have potential applications in the emerging field of drug-free tumor treatment.

Membrane-disruptive homo-polymethacrylate with both hydrophobicity and pH-sensitive protonation for selective cancer therapy

The membrane-disruptive strategy, which involves host defense peptides and their mimetics, is a revolutionary cancer treatment based on broad-spectrum anticancer activities. However, clinical application is limited by low selectivity towards tumors. In this context, we have established a highly selective anticancer polymer, i.e. poly(ethylene glycol)-poly(2-azepane ethyl methacrylate) (PEG-PAEMA), that can mediate the membrane-disruptive activity via a subtle pH change between physiological pH and tumor acidity for selective cancer treatment. Specifically, the resulting PEG-PAEMA can assemble into neutral nanoparticles and silence the membrane-disruptive activity at physiological pH and disassemble into cationic free-chains or smaller nanoparticles with potent membrane-disruptive activity after the protonation of the PAEMA block due to tumor acidity, resulting in high selectivity towards tumors. Dramatically, PEG-PAEMA exhibited a >200-fold amplification in hemolysis and <5% in IC₅₀ against Hepa1-6, SKOV3 and CT-26 cells at pH 6.7 as compared to those at pH 7.4, thanks to the selective membrane-disruptive mechanism. Moreover, mid- and high-dose PEG-PAEMA demonstrated higher anticancer efficacy than an optimal clinical prescription (bevacizumab plus PD-1) and, significantly, had few side effects on major organs in the tumor-bearing mice model, agreeing with the highly selective membrane-disruptive activity in vivo. Collectively, this work showcases the latent anticancer pharmacological activity of the PAEMA block, and also brings new hope for selective cancer therapy.

Design and synthesis of novel N-terminal peptides of integrin and aminopeptidase are new finding for anticancer activity

The short peptides, containing the amino acid sequence asparagine-glycine-arginine (NGR) and arginine-glycine-aspartic acid (RGD), possess the strong binding ability to N (APN/CD13) aminopeptidase receptor and integrin proteins involved in antitumor properties are overexpressed. A novel short N-terminal modified hexapeptides P1 and P2 was designed and synthesized using the Fmoc-chemistry solid phase peptide synthesis protocol. Notably, the cytotoxicity of the MTT assay demonstrated the viability of normal and cancer cells up to lower peptide concentrations. Interestingly, both peptides show good anticancer activities against the four cancer cells and normal cells namely, Hep-2, HepG2, MCF-7, A375, and Vero and compared with standard drugs, doxorubicin and paclitaxel. Additionally, in silico studies were applied to predict the binding sites and binding orientation of the peptides for potential anticancer targets. Steady-state fluorescence measurements showed that peptide P1 exhibits preferential interactions with POPC/POPG anionic bilayers rather than the zwitterionic POPC lipid bilayers and peptide P2, did not show any preferential interaction with lipids bilayers. But impressively, peptide P2 shows anticancer activity due to the NGR/RGD motif. Circular dichroism studies demonstrated that the peptide's secondary structure changes only minimally upon binding to the anionic lipid bilayers.

A Novel Strategy for the Design of Aurein 1.2 Analogs with Enhanced Bioactivities by Conjunction of Cell-Penetrating Regions

The rational design modification of membrane-active peptide structures by introducing additional membrane-penetrating regions has become a good strategy for the improvement of action and potency. Aurein 1.2 (GLFDIIKKIAESF-NH₂) is a multifunctional antimicrobial peptide isolated from the green and golden bell frog, Litoria aurea, and the southern bell frog Litoria raniformis skin secretions. Its bio-functionality has been widely investigated. However, its lack of a potent action failed to provide aurein 1.2 with a competitive edge for further development as a therapeutic agent for clinical use. Herein, aurein 1.2 was chosen as a template for rational modification to achieve a more potent bio-functionality. KLA-2 (GLFDIIKKLAKLAESF-NH₂), which a double KLA region inserted into the sequence, presented a 2-16-fold enhancement of antimicrobial activity, a 2-8-fold greater anti-biofilm activity (including biofilm prevention and eradication), and a 7-fold more potent anti-proliferation activity and hence was regarded as the most broad-spectrum active peptide. Additionally, with respect to antimicrobial activity, the IIKK-modified analog, IK-3 (GLFDIIKKIIKKIIKKI-NH₂), also demonstrated a potent enhancement of activity against various pathogens, exhibiting a 2-8-fold enhanced activity compared to the parent peptide. Moreover, the selectivities of KLA-1 and KLA-2 were enhanced significantly. In conclusion, peptide modification, through the introduction of additional membrane penetrating regions, can increase both the potency and activity spectra of natural template peptides, making them suitable candidates for new drug development.

Mechanistic insights and importance of hydrophobicity in cationic polymers for cancer therapy

Development of molecules that can be effectively used for killing cancer cells remains a research topic of interest in drug discovery. However, various limitations of small molecules and nanotechnology-based drug-delivery systems hinder the development of chemotherapeutics. To resolve this issue, this study describes the potential application of polymeric molecules as anticancer drug candidates. We describe the design and synthesis of novel anticancer polymers containing hydrophobic groups. We established the fact that the cationic homopolymer (PAMPTMA) does not show any anticancer activity on its own; however, the insertion of hydrophobic moieties in copolymers (PAMPTMA-r-BuMA, PAMPTMA-r-HexMA, and PAMPTMA-r-OctMA) enhances their anticancer activity with a very low IC₅₀ value (60 μg mL^-1 for HepG2 cells). Mechanistic investigations were carried out using LDH leakage assay, cellular uptake, DOSY NMR and molecular dynamics to study the interaction between the polymer and the cell membrane as well as the role of hydrophobicity in enhancing this interaction. The results demonstrated that polymers are attracted by the anionic cancer cell membrane, which then leads to the insertion of hydrophobic groups inside the cell membrane, causing its disruption and ultimate lysis of the cell. This study demonstrates a novel and better approach for the rational design and discovery of new polymeric anticancer agents with improved efficacy.

Combined Thermosensitive Gel Co-Loaded with Dermaseptin-PP and PTX Liposomes for Effective Local Chemotherapy

Introduction

Chemotherapeutic drugs are often ineffective due to the delivery. Local chemotherapy, which has high drug concentration, low systemic toxicity, and long duration, has shown excellent potential. Cationic antimicrobial peptides have been proved to enhance the tumor cells' uptake of chemotherapeutic drugs through the membrane-breaking effect. In this study, we designed and developed a thermosensitive gel co-loaded with Dermaseptin-PP and paclitaxel liposomes to increase local chemotherapy.

Methods

The paclitaxel liposomes were prepared. Then, it was co-loaded with Dermaseptin-PP in a poloxamer-based thermosensitive gel to obtain Dermaseptin-PP/paclitaxel liposomes gel. The thermosensitivity of gels was investigated by test tube inversion method. The rheology was tested by rheometer. The in vitro cytotoxicity and the permeation in tumor of gels were examined by H157 cells and the 3D cell model, respectively. The retention in tumor and antitumor activity of gels were evaluated by H157 tumor-bearing nude mice.

Results

The particle size of paclitaxel liposomes was 148.97 ± 0.21 nm. The encapsulation rate was 86.1%, and the drug loading capacity was 19.4%. The gels had slow-release and temperature-sensitive properties. The porous 3D network structure of the gels could ensure that the drug was fixed into the tumor. In vitro and in vivo distribution studies showed that Dermaseptin-PP promoted the permeation of the gels in H157 multicellular tumor spheres and achieved longer retention in tumor. In vitro and in vivo antitumor studies demonstrated that Dermaseptin-PP/paclitaxel liposomes gel significantly inhibited the growth of tumors for local chemotherapy with good biosafety.

Conclusion

This study provided a promising nanomedicine platform for combining antimicrobial peptides and chemotherapeutic drugs for local chemotherapy.

Wnt Signaling Pathway Collapse upon β-Catenin Destruction by a Novel Antimicrobial Peptide SKACP003: Unveiling the Molecular Mechanism and Genetic Activities Using Breast Cancer Cell Lines

Despite progress in breast cancer treatment, the survival rate for patients with metastatic breast cancer remains low due to chemotherapeutic agent resistance and the lack of specificity of the current generation of cancer drugs. Our previous findings indicated that the antimicrobial peptide SKACP003 exhibited anticancer properties, particularly against the MCF-7, MDA-MB-231, and MDA-MB-453 breast cancer cell lines. However, the mechanism of SKACP003-induced cancer cell death is unknown. Here, we investigated the molecular mechanism by which SKACP003 inhibits the cell cycle, cell proliferation, and angiogenesis in breast cancer cell lines. The results revealed that all the breast cancer cell lines treated at their IC₅₀ values significantly inhibited the replicative phase of the cell cycle. The SKACP003-induced growth inhibition induced apoptosis, as evidenced by a decrease in BCL-2 and an increase in BAX and caspase gene (Cas-3, Cas-8, and Cas-9) expression. Reduced expression of the β-Catenin signaling pathway was associated with the SKACP003-induced apoptosis. SKACP003-treated breast cancer cells showed decreased expression of Wnt/β-Catenin targeting genes such as C-Myc, P⁶⁸, and COX-2 and significant downregulation of CDK-4 and CDK-6 genes. Furthermore, cytoplasmic β-catenin protein levels in SKACP003-treated cell lines were significantly lower than in control cell lines. The results of the current study suggest that the newly identified antimicrobial peptide SKACP003 has great potential as a candidate for specifically targeting the β-catenin and thus significantly reducing the progression and prognosis of breast cancer cell lines.

Nanomaterials in anticancer applications and their mechanism of action - A review

The current challenges in cancer treatment using conventional therapies have made the emergence of nanotechnology with more advancements. The exponential growth of nanoscience has drawn to develop nanomaterials (NMs) with therapeutic activities. NMs have enormous potential in cancer treatment by altering the drug toxicity profile. Nanoparticles (NPs) with enhanced surface characteristics can diffuse more easily inside tumor cells, thus delivering an optimal concentration of drugs at tumor site while reducing the toxicity. Cancer cells can be targeted with greater affinity by utilizing NMs with tumor specific constituents. Furthermore, it bypasses the bottlenecks of indiscriminate biodistribution of the antitumor agent and high administration dosage. Here, we focus on the recent advances on the use of various nanomaterials for cancer treatment, including targeting cancer cell surfaces, tumor microenvironment (TME), organelles, and their mechanism of action. The paradigm shift in cancer management is achieved through the implementation of anticancer drug delivery using nano routes.

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.

Microbial cancer therapeutics: A promising approach

The success of conventional cancer therapeutics is hindered by associated dreadful side-effects of antibiotic resistance and the dearth of antitumor drugs' selectivity and specificity. Hence, the conceptual evolution of anti-cancerous therapeutic agents that selectively target cancer cells without impacting the healthy cells or tissues, has led to a new wave of scientific interest in microbial-derived bioactive molecules. Such strategic solutions may pave the way to surmount the shortcomings of conventional therapies and raise the potential and hope for the cure of wide range of cancer in a selective manner. This review aims to provide a comprehensive summary of anti-carcinogenic properties and underlying mechanisms of bioactive molecules of microbial origin, and discuss the current challenges and effective therapeutic application of combinatorial strategies to attain minimal systemic side-effects.

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.

Bacterial Peptides and Bacteriocins as a Promising Therapy for Solid Tumor

The conventional treatment is faced with limitations in treating solid tumors due to their specific pathophysiology. Several novel therapeutics have been introduced in recent decades to treat solid tumors. Among these new methods, tumor therapy using bacterial products like bacteriocins and peptides has been of great interest due to their unique characteristics and advantages of them in comparison to the conventional treatment, including that they can precisely target tumor cells, selective toxicity for tumor cells, low side effect on normal cells, toxicity activity for MDR cancer cells, used as the target delivery vehicles and enhancing drug delivery. Moreover, their small size and low molecular weight have made them easy to synthesize and modify. Furthermore, in recent years, genetic engineering has expanded the therapeutic ability of peptides to treat solid tumors, which results in overcoming the peptide drawbacks. The present review mainly focuses on the new advances in applying bacterial peptides and bacteriocins in treating human solid tumors.

Machine Learning Guided Discovery of Non-Hemolytic Membrane Disruptive Anticancer Peptides

Most antimicrobial peptides (AMPs) and anticancer peptides (ACPs) fold into membrane disruptive cationic amphiphilic α-helices, many of which are however also unpredictably hemolytic and toxic. Here we exploited the ability of recurrent neural networks (RNN) to distinguish active from inactive and non-hemolytic from hemolytic AMPs and ACPs to discover new non-hemolytic ACPs. Our discovery pipeline involved: 1) sequence generation using either a generative RNN or a genetic algorithm, 2) RNN classification for activity and hemolysis, 3) selection for sequence novelty, helicity and amphiphilicity, and 4) synthesis and testing. Experimental evaluation of thirty-three peptides resulted in eleven active ACPs, four of which were non-hemolytic, with properties resembling those of the natural ACP lasioglossin III. These experiments show the first example of direct machine learning guided discovery of non-hemolytic ACPs.

Designed Multifunctional Peptides for Intracellular Targets

Nature’s way for bioactive peptides is to provide them with several related functions and the ability to cooperate in performing their job. Natural cell-penetrating peptides (CPP), such as penetratins, inspired the design of multifunctional constructs with CPP ability. This review focuses on known and novel peptides that can easily reach intracellular targets with little or no toxicity to mammalian cells. All peptide candidates were evaluated and ranked according to the predictions of low toxicity to mammalian cells and broad-spectrum activity. The final set of the 20 best peptide candidates contains the peptides optimized for cell-penetrating, antimicrobial, anticancer, antiviral, antifungal, and anti-inflammatory activity. Their predicted features are intrinsic disorder and the ability to acquire an amphipathic structure upon contact with membranes or nucleic acids. In conclusion, the review argues for exploring wide-spectrum multifunctionality for novel nontoxic hybrids with cell-penetrating peptides.

Design, Synthesis and Activity of New N1-Alkyl Tryptophan Functionalized Dendrimeric Peptides against Glioblastoma

Background: Due to resistance to conventional therapy, a blood–brain barrier that results in poor drug delivery, and a high potential for metastasis, glioblastoma (GBM) presents a great medical challenge. Since the repertoire of the possible therapies is very limited, novel therapeutic strategies require new drugs as well as new approaches. The multiple roles played by L-tryptophan (Trp) in tumorigenesis of GBM and the previously found antiproliferative properties of Trp-bearing dendrimers against this malignancy prompted us to design novel polyfunctional peptide-based dendrimers covalently attached to N¹-alkyl tryptophan (Trp) residues. Their antiproliferative properties against GBM and normal human astrocytes (NHA) and their antioxidant potential were tested. Methods: Two groups of amphiphilic peptide dendrimers terminated with N¹-butyl and N¹-aminopentane tryptophan were designed. The influence of dendrimers on viability of NHA and human GBM cell lines, displaying different genetic backgrounds and tumorigenic potentials, was determined by the MTT test. The influence of compounds on the clonogenic potential of GBM cells was assessed by colony-formation assay. Dendrimers were tested for radical scavenging potency as well as redox capability (DPPH, ABTS, and FRAP models). Results: Several peptide dendrimers functionalized with N¹-alkyl-tryptophan at 5 µM concentration exhibited high selectivity towards GBM cells retaining 85–95% viable NHA cells while killing cancer cells. In both the MTT and colony-formation assays, compounds 21 (functionalized with N¹-butyl-Trp and (+)8 charged) and 25 (functionalized with N¹-aminopentane-Trp and (+)12 charged) showed the most promise for their development into anticancer drugs. According to ABTS, DPPH, and FRAP antioxidant tests, dendrimers functionalized with N¹-alkylated Trp expressed higher ROS-scavenging capacity (ABTS and DPPH) than those with unsubstituted Trp. Conclusions: Peptide dendrimers functionalized with N¹-alkyl-tryptophan showed varying toxicity to NHA, while all were toxic to GBM cells. Based on their activity towards inhibition of GBM viability and relatively mild effect on NHA cells the most advantageous were derivatives 21 and 25 with the respective di-dodecyl and dodecyl residue located at the C-terminus. As expected, peptide dendrimers functionalized with N¹-alkyl-tryptophan expressed higher scavenging potency against ROS than dendrimers with unsubstituted tryptophan.

Towards in vivo photomediated delivery of anticancer peptides: Insights from pharmacokinetic and -dynamic data

An in vivo study of a photoswitchable cytotoxic peptide LMB040 has been undertaken on a chemically induced hepatocellular carcinoma model in immunocompetent rats. We analysed the pharmacokinetic profile of the less toxic photoform ("ring-closed" dithienylethene) of the compound in tumors, plasma, and healthy liver. Accordingly, the peptide can reach a tumor concentration sufficiently high to exert a cytotoxic effect upon photoconversion into the more active ("ring-open") photoform. Tissue morphology, histology, redox state of the liver, and hepatic biochemical parameters in blood serum were analysed upon treatment with (i) the less active photoform, (ii) the in vivo light-activated alternative photoform, and (iii) compared with a reference chemotherapeutic 5-fluorouracil. We found that application of the less toxic form followed by a delayed in vivo photoconversion into the more toxic ring-open form of LMB040 led to a higher overall survival of the animals, and signs of enhanced immune response were observed compared to the untreated animals.

Cationic antimicrobial peptide NRC-03 induces oral squamous cell carcinoma cell apoptosis via CypD-mPTP axis-mediated mitochondrial oxidative stress

Pleurocidin-family cationic antimicrobial peptide NRC-03 exhibits potent and selective cytotoxicity towards cancer cells. However, the anticancer effect of NRC-03 in oral squamous cell carcinoma (OSCC) and the molecular mechanism of NRC-03 induced cancer cell death is still unclear. This study focused to investigate mitochondrial oxidative stress-mediated altered mitochondrial function involved in NRC-03-induced apoptosis of OSCC cells. NRC-03 entered the OSCC cells more easily than that of normal cells and bound to mitochondria as well as the nucleus, causing cell membrane blebbing, mitochondria swelling, and DNA fragmentation. NRC-03 induced high oxygen consumption, reactive oxygen species (ROS) release, mitochondrial dysfunction, and apoptosis in OSCC cells. Non-specific antioxidant N-acetyl-l-cysteine (NAC), or mitochondria-specific antioxidant mitoquinone (MitoQ) alleviated NRC-03-induced apoptosis and mitochondrial dysfunction indicated that NRC-03 exerts a cytotoxic effect in cancer cells via inducing cellular and mitochondrial oxidative stress. Moreover, the expression of cyclophilin D (CypD), the key component of mitochondrial permeability transition pore (mPTP), was upregulated in NRC-03-treated cancer cells. Blockade of CypD by siRNA-mediated depletion or pharmacological inhibitor cyclosporine A (CsA) significantly suppressed NRC-03-induced mitochondrial oxidative stress, mitochondrial dysfunction, and apoptosis. NRC-03 also activated MAPK/ERK and NF-κB pathways. Importantly, intratumoral administration of NRC-03 inhibited the growth of CAL-27 cells-derived tumors on xenografted animal models. Taken together, our study indicates that NRC-03 induces apoptosis in OSCC cells via the CypD-mPTP axis mediated mitochondrial oxidative stress.

Host Defense Peptides at the Ocular Surface: Roles in Health and Major Diseases, and Therapeutic Potentials

Sight is arguably the most important sense in human. Being constantly exposed to the environmental stress, irritants and pathogens, the ocular surface – a specialized functional and anatomical unit composed of tear film, conjunctival and corneal epithelium, lacrimal glands, meibomian glands, and nasolacrimal drainage apparatus – serves as a crucial front-line defense of the eye. Host defense peptides (HDPs), also known as antimicrobial peptides, are evolutionarily conserved molecular components of innate immunity that are found in all classes of life. Since the first discovery of lysozyme in 1922, a wide range of HDPs have been identified at the ocular surface. In addition to their antimicrobial activity, HDPs are increasingly recognized for their wide array of biological functions, including anti-biofilm, immunomodulation, wound healing, and anti-cancer properties. In this review, we provide an updated review on: (1) spectrum and expression of HDPs at the ocular surface; (2) participation of HDPs in ocular surface diseases/conditions such as infectious keratitis, conjunctivitis, dry eye disease, keratoconus, allergic eye disease, rosacea keratitis, and post-ocular surgery; (3) HDPs that are currently in the development pipeline for treatment of ocular diseases and infections; and (4) future potential of HDP-based clinical pharmacotherapy for ocular diseases.

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.

Anticancer activity of chicken cathelicidin peptides against different types of cancer

BACKGROUND

This study served as the pioneer in studying the anti-cancer role of chicken cathelicidin peptides.

METHODS AND RESULTS

Chicken cathelicidins were used as anticancer agent against the breast cancer cell line (MCF-7) and human colon cancer cell line (HCT116). In addition, the mechanism of action of the interaction of cationic peptides with breast cancer cell line MCF-7 was also investigated. An in vivo investigation was also achieved to evaluate the role of chicken cathelicidin in Ehrlich ascites cell (EAC) suppression as a tumor model after subcutaneous implantation in mice. It was found during the study that exposure of cell lines to 40 µg/ml of chicken cathelicidin for 72 h reduced cell lines growth rate by 90-95%. These peptides demonstrated down-regulation of (cyclin A1 and cyclin D genes) of MCF-7 cells. The study showed that two- and three-fold expression of both of caspase-3 and - 7 genes in untreated MCF-7 cells compared to treated MCF-7 cells with chicken cathelicidin peptides. Our data showed that chicken (CATH-1) enhance releasing of TNFα, INF-γ and upregulation of granzyme K in treated mice groups, in parallel, the tumor size and volume was reduced in the treated EAC-bearing groups. Tumor of mice groups treated with chicken cathelicidin displayed high area of necrosis compared to untreated EAC-bearing mice. Based on histological analysis and immunohistochemical staining revealed that the tumor section in Ehrlich solid tumor exhibited a strong Bcl2 expression in untreated control compared to mice treated with 10 & 20 µg of cathelicidin. Interestingly, low expression of Bcl2 were observed in mice taken 40 µg/mL of CATH-1.

CONCLUSIONS

This study drive intention in treatment of cancer through the efficacy of anticancer efficacy of chicken cathelicidin peptides.

Heterochiral β-Peptide Polymers Combating Multidrug-Resistant Cancers Effectively without Inducing Drug Resistance

Multidrug resistance to chemotherapeutic drugs is one of the major causes for the failure of cancer treatment. Therefore, there is an urgent need to develop anticancer agents that can combat multidrug-resistant cancers effectively and mitigate drug resistance. Here, we report a rational design of anticancer heterochiral β-peptide polymers as synthetic mimics of host defense peptides to combat multidrug-resistant cancers. The optimal polymer shows potent and broad-spectrum anticancer activities against multidrug-resistant cancer cells and is insusceptible to anticancer drug resistance owing to its membrane-damaging mechanism. The in vivo study indicates that the optimal polymer efficiently inhibits the growth and distant transfer of solid tumors and the metastasis and seeding of circulating tumor cells. Moreover, the polymer shows excellent biocompatibility during anticancer treatment on animals. In addition, the β-peptide polymers address those prominent shortcomings of anticancer peptides and have superior stability against proteolysis, easy synthesis in large scale, and low cost. Collectively, the structural diversity and superior anticancer performance of β-peptide polymers imply an effective strategy in designing and finding anticancer agents to combat multidrug-resistant cancers effectively while mitigating drug resistance.

Bacteria-Mediated Modulatory Strategies for Colorectal Cancer Treatment

Colorectal cancer (CRC) is one of the most common tumors worldwide, with a higher rate of distant metastases than other malignancies and with regular occurrence of drug resistance. Therefore, scientists are forced to further develop novel and innovative therapeutic treatment strategies, whereby it has been discovered microorganisms, albeit linked to CRC pathogenesis, are able to act as highly selective CRC treatment agents. Consequently, researchers are increasingly focusing on bacteriotherapy as a novel therapeutic strategy with less or no side effects compared to standard cancer treatment methods. With multiple successful trials making use of various bacteria-associated mechanisms, bacteriotherapy in cancer treatment is on its way to become a promising tool in CRC targeting therapy. In this study, we describe the anti-cancer effects of bacterial therapy focusing on the treatment of CRC as well as diverse modulatory mechanisms and techniques that bacteriotherapy offers such as bacterial-related biotherapeutics including peptides, toxins, bacteriocins or the use of bacterial carriers and underlying molecular processes to target colorectal tumors.

Drug-free neutrally charged polypeptide nanoparticles as anticancer agents

Cationic synthetic anticancer polymers and peptides have attracted increasing attention for advancing cancer treatment without causing drug resistance development. To circumvent in vivo instability and toxicity caused by cationic charges of the anticancer polymers/peptides, we report, for the first time, a nanoparticulate delivery system self-assembled from a negatively charged pH-sensitive polypeptide poly(ethylene glycol)-b-poly(ʟ-lysine)-graft-cyclohexene-1,2-dicarboxylic anhydride and a cationic anticancer polypeptide guanidinium-functionalized poly(ʟ-lysine) (PLL-Gua) via electrostatic interaction. The formation of nanoparticles (Gua-NPs) neutralized the positive charges of PLL-Gua. Both PLL-Gua and Gua-NPs killed cancer cells in a dose- and time-dependent manner, and induced cell death via apoptosis. Confocal microscopic studies demonstrated that PLL-Gua and Gua-NPs readily entered cancer cells, and Gua-NPs were taken up by the cells via endocytosis. Notably, Gua-NPs and PLL-Gua exhibited similar in vitro anticancer efficacy against MCF-7 and resistant MCF-7/ADR. PLL-Gua and Gua-NPs also induced similar morphological changes in MCF-7/ADR cells compared to MCF-7 cells, further indicating their ability to bypass drug resistance mechanisms in the MCF-7/ADR cells. More importantly, Gua-NPs with higher LD₅₀ and enhanced tumor accumulation significantly inhibited tumor growth with negligible side effects in vivo. Our findings shed light on the in vivo delivery of anticancer peptides and opened a new avenue for cancer treatment.

Clinical Applications and Anticancer Effects of Antimicrobial Peptides: From Bench to Bedside

Cancer is a multifaceted global health issue and one of the leading causes of death worldwide. In recent years, medical science has achieved great advances in the diagnosis and treatment of cancer. Despite the numerous advantages of conventional cancer therapies, there are major drawbacks including severe side effects, toxicities, and drug resistance. Therefore, the urgency of developing new drugs with low cytotoxicity and treatment resistance is increasing. Antimicrobial peptides (AMPs) have attracted attention as a novel therapeutic strategy for the treatment of various cancers, targeting tumor cells with less toxicity to normal tissues. In this review, we present the structure, biological function, and underlying mechanisms of AMPs. The recent experimental studies and clinical trials on anticancer peptides in different cancer types as well as the challenges of their clinical application have also been discussed.

The antimetastatic breast cancer activity of the viral protein-derived peptide vCPP2319 as revealed by cellular biomechanics

The incidence of metastatic breast cancer (MBC) is increasing and the therapeutic arsenal available to fight it is insufficient. Brain metastases, in particular, represent a major challenge for chemotherapy as the impermeable nature of the blood-brain barrier (BBB) prevents most drugs from targeting cells in the brain. For their ability to transpose biological membranes and transport a broad spectrum of bioactive cargoes, cell-penetrating peptides (CPPs) have been hailed as ideal candidates to deliver drugs across biological barriers. A more ambitious approach is to have the CPP as a drug itself, capable of both killing cancer cells and interacting with the blood/brain interface, therefore blocking the onset of brain metastases. vCPP2319, a viral protein-derived CPP, has both properties as it: (a) is selective toward human breast cancer cells (MDA-MB-231) and increases cell stiffness compared to breast epithelial cells (MCF 10A) hindering the progression of metastases; and (b) adsorbs at the surface of human brain endothelial cells potentially counteracting metastatic cells from reaching the brain. Overall, the results reveal the selective anticancer activity of the peptide vCPP2319, which is also able to reside at the blood-brain interface, therefore counteracting brain penetration by metastatic cancer cells.

Rationally designed cationic amphiphilic peptides for selective gene delivery to cancer cells

Gene therapy has gained increasing attention as an alternative to pharmacotherapy for treatment of various diseases. The extracellular and intracellular barriers to gene delivery necessitate the use of gene vectors which has led to the development of myriads of gene delivery systems. However, many of these gene delivery systems have pitfalls such as low biocompatibility, low loading efficiency, low transfection efficiency, lack of tissue selectivity and high production costs. Herein, we report the development of a new series of short cationic amphiphilic peptides with anticancer activity for selective delivery of small interfering RNA (siRNA) and antisense oligodeoxynucleotides (ODNs) to cancer cells. The peptides consist of alternating dyads of hydrophobic (isoleucine (I) or leucine (L)) and hydrophilic (arginine (R) or lysine (L)) amino acids. The peptides exhibited higher preference for transfection of HCT 116 colorectal cancer cells compared to human dermal fibroblasts (HDFs) and induced higher level of gene silencing in the cancer cells. The nucleic acid complexation and transfection efficiency of the peptides was a function of their secondary structure, their hydrophobicity and their C-terminal amino acid. The peptides containing L in their hydrophobic domain formed stronger complexes with siRNA and successfully delivered it to the cancer cells but were unable to release their cargo inside the cells and therefore could not induce any gene silencing. On the contrary, the peptides containing I in their hydrophobic domain were able to release their associated siRNA and induce considerable gene silencing in cancer cells. The peptides exhibited higher selectivity for colorectal cancer cells and induced less gene silencing in fibroblasts compared to the lipid-based commercial transfection reagent DharmaFECT™ 1. The results from this study can serve as a tool for rational design of new peptide-based gene vectors for high selective gene delivery to cancer cells.

A Fungal Defensin Inhibiting Bacterial Cell-Wall Biosynthesis with Non-Hemolysis and Serum Stability

Defensins are a class of cationic disulfide-bridged antimicrobial peptides (AMPs) present in many eukaryotic organisms and even in bacteria. They primarily include two distinct but evolutionarily related superfamilies (cis and trans). Defensins in fungi belong to the members of the cis-superfamily with the cysteine-stabilized α-helical and β-sheet fold. To date, many fungal defensin-like peptides (fDLPs) have been found through gene mining of the genome resource, but only a few have been experimentally characterized. Here, we report the structural and functional characterization of Pyronesin4 (abbreviated as Py4), a fDLP previously identified by genomic sequencing of the basal filamentous ascomycete Pyronema confluens. Chemically, synthetic Py4 adopts a native-like structure and exhibits activity on an array of Gram-positive bacteria including some clinical isolates of Staphylococcus and Staphylococcus warneri, a conditioned pathogen inhabiting in human skin. Py4 markedly altered the bacterial morphology and caused cytoplasmic accumulation of the cell-wall synthesis precursor through binding to the membrane-bound Lipid II, indicating that it works as an inhibitor of cell-wall biosynthesis. Py4 showed no hemolysis and high mammalian serum stability. This work identified a new fungal defensin with properties relevant to drug exploration. Intramolecular epistasis between mutational sites of fDLPs is also discussed.

LvHemB1, a novel cationic antimicrobial peptide derived from the hemocyanin of Litopenaeus vannamei, induces cancer cell death by targeting mitochondrial voltage-dependent anion channel 1

Current cancer treatment regimens such as chemotherapy and traditional chemical drugs have adverse side effects including the appearance of drug-resistant tumor cells. For these reasons, it is imperative to find novel therapeutic agents that overcome these factors. To this end, we explored a cationic antimicrobial peptide derived from Litopenaeus vannamei hemocyanin (designated LvHemB1) that induces cancer cell death, but sparing normal cells. LvHemB1 inhibits the proliferation of human cervical (HeLa), esophageal (EC109), hepatocellular (HepG2), and bladder (EJ) cancer cell lines, but had no significant effect on normal liver cell lines (T-antigen-immortalized human liver epithelial (THLE-3) cells). In addition to its antiproliferative effects, LvHemB1 induced apoptosis, by permeating cells and targeting mitochondrial voltage-dependent anion channel 1 (VDAC1). Colocalization studies revealed the localization of LvHemB1 in mitochondria, while molecular docking and pull-down analyses confirmed LvHemB1-VDAC1 interaction. Moreover, LvHemB1 causes loss in mitochondrial membrane potential and increases levels of reactive oxygen species (ROS) and apoptotic proteins (caspase-9, caspase-3, and Bax (Bcl-2-associated X)), which results in mitochondrial-mediated apoptosis. Thus, peptide LvHemB1 has the potential of being used as an anticancer agent due to its antiproliferation effect and targeting to VDAC1 to cause mitochondrial dysfunction in cancer cells, as well as its ability to induce apoptosis by increasing ROS levels, and the expression of proapoptotic proteins.

Characterization of novel heterocyclic compounds based on 4-aryl-4H-chromene scaffold as anticancer agents: Design, synthesis, antiprofilerative activity against resistant cancer cells, dual β-tubulin/c-Src inhibition, cell cycle arrest and apoptosis induction

In this study, three novel sets of 4-aryl-4H-chromene derivatives 4a-c, 6a-d and 7a-c were synthesized and evaluated for anticancer activity. Characterization of new compounds was established on basis of elemental analyses and spectral data. All new compounds were investigated for their antiproliferative activity against HCT-116, HepG-2 and MCF-7 cell lines using vinblastine and staurosporine as positive controls. Compounds 4b, 4c and 6d showed superior cytotoxicity against HCT-116, HepG-2 and MCF-7 cell lines, respectively with IC₅₀ ranged from 3.31 to 4.95 μM. Additionally, compound 4b showed excellent cytotoxic activity (IC₅₀ = 39.83 μM) against resistant HCT-116 better than doxorubicin (IC₅₀ = 164.60 μM), while compounds 4c and 6d exhibited moderate cytotoxic activity against resistant HepG-2 and resistant MCF-7 cell lines. The most potent compounds inhibited both β-tubulin polymerization (IC₅₀ = 8.78 - 16.47 μM) and c-Src kinase (IC₅₀ = 0.07 - 0.18 μM) enzymes. Compounds 4b, 4c and 6d activated caspase-3, caspase-7, and caspase-9 proteins relative to untreated cells, revealing apoptosis induction. Apoptosis was also confirmed through up-regulation of Bax and down-regulation of Bcl-2 protein expression levels. Cell cycle analysis of compound 6d showed accumulation of cells in pre-G1 phase and cell cycle arrest at S phase in MCF-7 treated cells. As well 6d caused 7- and 63- fold increase in apoptotic cell population at early and late apoptosis stages. Finally, molecular modeling study was performed to predict the binding pattern of the target compounds inside c-Src kinase receptor.

Bioactive cationic peptides as potential agents for breast cancer treatment

Breast cancer continues to affect millions of women worldwide, and the number of new cases dramatically increases every year. The physiological causes behind the disease are still not fully understood. One in every 100 cases can occur in men, and although the frequency is lower than among women, men tend to have a worse prognosis of the disease. Various therapeutic alternatives to combat the disease are available. These depend on the type and progress of the disease, and include chemotherapy, radiotherapy, surgery, and cancer immunotherapy. However, there are several well-reported side effects of these treatments that have a significant impact on life quality, and patients either relapse or are refractory to treatment. This makes it necessary to develop new therapeutic strategies. One promising initiative are bioactive peptides, which have emerged in recent years as a family of compounds with an enormous number of clinical applications due to their broad spectrum of activity. They are widely distributed in several organisms as part of their immune system. The antitumoral activity of these peptides lies in a nonspecific mechanism of action associated with their interaction with cancer cell membranes, inducing, through several routes, bilayer destabilization and cell death. This review provides an overview of the literature on the evaluation of cationic peptides as potential agents against breast cancer under different study phases. First, physicochemical characteristics such as the primary structure and charge are presented. Secondly, information about dosage, the experimental model used, and the mechanism of action proposed for the peptides are discussed.

Selective targeting of the novel CK-10 nanoparticles to the MDA-MB-231 breast cancer cells

The main objective of this project was to formulate novel decorated amphiphilic PLGA nanoparticles aiming for the selective delivery of the novel peptide (CK-10) to the cancerous/tumor tissue. Novel modified microfluidic techniques were used to formulate the nanoparticles. This technique was modified by using of Nano Assemblr associated with salting out of the organic solvent using K₂HPO₄. This modification is associated with higher peptide loading efficiencies, smaller size and higher uniformity. Size, zeta potential & qualitative determination of the adsorbed targeting ligands were measured by dynamic light scattering and laser anemometry techniques using the zeta sizer. Quantitative estimation of the adsorbed targeting ligands was done by colorimetry and spectrophotometric techniques. Qualitative and quantitative uptakes of the various PLGA nanoparticles were examined by the fluorescence microscope and the flow cytometer while the cytotoxic effect of the nanoparticles was measured by the colorimetric MTT assay. PLGA/poloxamer.FA, PLGA/poloxamer.HA, and PLGA/poloxamer.Tf have breast cancer MDA. MB321 cellular uptakes 83.8, 75.43 & 69.37 % which are higher than those of the PLGA/B cyclodextrin.FA, PLGA/B cyclodextrin.HA and PLGA/B cyclodextrin.Tf 80.87, 74.47 & 64.67 %. Therefore, PLGA/poloxamer.FA and PLGA/poloxamer.HA show higher cytotoxicity than PLGA/ poloxamer.Tf with lower breast cancer MDA-MB-231 cell viabilities 30.74, 39.15 & 49.23 %, respectively. The design of novel decorated amphiphilic CK-10 loaded PLGA nanoparticles designed by the novel modified microfluidic technique succeeds in forming innovative anticancer formulations candidates for therapeutic use in aggressive breast cancers.