Anti-Tumor Effects of Melittin and Its Potential Applications in Clinic

Unlocking nature's arsenal: Nanotechnology for targeted delivery of venom toxins in cancer therapy

AIM

The aim of the present review is to shed light on the nanotechnological approaches adopted to overcome the shortcomings associated with the delivery of venom peptides which possess inherent anti-cancer properties.

BACKGROUND

Venom peptides although have been reported to demonstrate anti-cancer effects, they suffer from several disadvantages such as in vivo instability, off-target adverse effects, limited drug loading and low bioavailability. This review presents a comprehensive compilation of different classes of nanocarriers while underscoring their advantages, disadvantages and potential to carry such peptide molecules for in vivo delivery. It also discusses various nanotechnological aspects such as methods of fabrication, analytical tools to assess these nanoparticulate formulations, modulation of nanocarrier polymer properties to enhance loading capacity, stability and improve their suitability to carry toxic peptide drugs.

CONCLUSION

Nanotechnological approaches bear great potential in delivering venom peptide-based molecules as anticancer agents by enhancing their bioavailability, stability, efficacy as well as offering a spatiotemporal delivery approach. However, the challenges associated with toxicity and biocompatibility of nanocarriers must be duly addressed.

PERSPECTIVES

The everlasting quest for new breakthroughs for safer delivery of venom peptides in human subjects is fuelled by unmet clinical needs in the current landscape of chemotherapy. In addition, exhaustive efforts are required in obtaining and purifying the venom peptides followed by designing and optimizing scale up technologies.

A novel recombinant adenovirus expressing apoptin and melittin genes kills hepatocellular carcinoma cells and inhibits the growth of ectopic tumor

HCC is the most common fatal malignancy. Although surgical resection is the primary treatment strategy, most patients are not eligible for resection due to tumor heterogeneity, underlying liver disease, or comorbidities. Therefore, this study explores the possibility of multi-molecular targeted drug delivery in treating HCC. In this study, we constructed the recombinant adenovirus co-expressing apoptin and melittin (MEL) genes. The inhibitory effect of the recombinant adenovirus on hepatocellular carcinoma cells was detected through experiments on cell apoptosis, migration, invasion, and other factors. The tumor inhibitory effect in vivo was assessed using subcutaneous HCC mice. Results showed that recombinant adenovirus co-expressing anti-tumor genes TAT and apoptin, RGD and MEL can significantly inhibit the proliferation, migration, and invasion of HCC cells by inducing an increase in reactive oxygen species (ROS) levels, upregulation of apoptotic proteins such as Bax, cleaved caspase-3, and cleaved caspase-9, and downregulation of the anti-apoptotic protein Bcl-2. In subcutaneous HCC mice, recombinant adenovirus induced significant apoptosis in tumor, and inhibited tumor growth. In conclusion, recombinant adenovirus co-expressing apoptin and MEL can inhibit the growth and proliferation of tumor cells both in vivo and in vitro.

Clickable tryptophan modification for late-stage diversification of native peptides

As the least abundant residue in proteins, tryptophan widely exists in peptide drugs and bioactive natural products and contributes to drug-target interactions in multiple ways. We report here a clickable tryptophan modification for late-stage diversification of native peptides, via catalyst-free C2-sulfenylation with 8-quinoline thiosulfonate reagents in trifluoroacetic acid (TFA). A wide range of groups including trifluoromethylthio (SCF3), difluoromethylthio (SCF2H), (ethoxycarbonyl)difluoromethylthio (SCF2CO2Et), alkylthio, and arylthio were readily incorporated. The rapid reaction kinetics of Trp modification and full tolerance with other 19 proteinogenic amino acids, as well as the super dissolving capability of TFA, render this method suitable for all kinds of Trp-containing peptides without limitations from sequences, hydrophobicity, and aggregation propensity. The late-stage modification of 15 therapeutic peptides (1.0 to 7.6 kilodaltons) and the improved bioactivity and serum stability of SCF3- and SCF2H-modified melittin analogs illustrated the effectiveness of this method and its potential in pharmacokinetic property improvement.

Hybrid bio-nanoporous peptide loaded-polymer platforms with anticancer and antibacterial activities

In this study, hybrid bio-nanoporous peptides loaded onto poly(N-isopropylacrylamide-co-butylacrylate) (pNIPAM-co-BA) coatings were designed and obtained via matrix-assisted pulsed laser evaporation (MAPLE) technique. The incorporation of cationic peptides magainin (MG) and melittin (Mel) and their combination was tailored to target synergistic anticancer and antibacterial activities with low toxicity on normal mammalian cells. Atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy as well as contact angle and surface energy measurements revealed the successful and functional incorporation of both the peptides within porous polymeric nanolayers as well as surface modifications (i.e. variation in the pore size diameter, surface roughness, and wettability) after Mel, MG or Mel-MG incorporation compared to pNIPAM-co-BA. In vitro testing revealed the impairment of biofilm formation on all the hybrid coatings while testing with S. aureus, E. coli and P. aeruginosa. Moreover, MG was shown to modulate the effect of Mel in the combined Mel-MG extract formulation released via pNIPAM-platforms, thus significantly reducing cancer cell proliferation through apoptosis/necrosis as revealed by flow cytometry analysis performed in vitro on HEK293T, A375, B16F1 and B16F10 cells. To the best of our knowledge, Mel-MG combination entrapped in the pNIPAM-co-BA copolymer has not yet been reported as a new promising candidate with anticancer and antibacterial properties for improved utility in the biomedical field. Mel-MG incorporation compared to pNIPAM-co-BA in in vitro testing revealed the impairment of biofilm formation in all the hybrid formulations.

Anti-Staphylococcus aureus effects of natural antimicrobial peptides and the underlying mechanisms

Staphylococcus aureus can cause localized infections such as abscesses and pneumonia, as well as systemic infections such as bacteremia and sepsis. Especially, methicillin-resistant S. aureus often presents multidrug resistance, which becomes a major clinical challenge. One of the most common reasons for methicillin-resistant S. aureus antibiotic resistance is the presence of biofilms. Natural antimicrobial peptides derived from different species have shown effectiveness in combating S. aureus biofilms. In this review, we summarize the inhibitory activity of antimicrobial peptides against S. aureus planktonic cells and biofilms. We also summarize the possible inhibitory mechanisms, involving cell adhesion inhibition, membrane fracture, biofilm disruption and DNA disruption. We believe this can provide the basis for further research against S. aureus biofilm-associated infections.

Neuroprotective Effects of Melittin Against Cerebral Ischemia and Inflammatory Injury via Upregulation of MCPIP1 to Suppress NF-κB Activation In Vivo and In Vitro

Melittin, a principal constituent of honeybee venom, exhibits diverse biological effects, encompassing anti-inflammatory capabilities and neuroprotective actions against an array of neurological diseases. In this study, we probed the prospective protective influence of melittin on cerebral ischemia, focusing on its anti-inflammatory activity. Mechanistically, we explored whether monocyte chemotactic protein-induced protein 1 (MCPIP1, also known as ZC3H12A), a recently identified zinc-finger protein, played a role in melittin-mediated anti-inflammation and neuroprotection. Male C57/BL6 mice were subjected to distal middle cerebral artery occlusion to create a focal cerebral cortical ischemia model, with melittin administered intraperitoneally. We evaluated motor functions, brain infarct volume, cerebral blood flow, and inflammatory marker levels within brain tissue, employing quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assays, and western blotting. In vitro, an immortalized BV-2 microglia culture was stimulated with lipopolysaccharide (LPS) to establish an inflammatory cell model. Post-melittin exposure, cell viability, and cytokine expression were examined. MCPIP1 was silenced using siRNA in LPS-induced BV-2 cells, with the ensuing nuclear translocation of nuclear factor-κB assessed through cellular immunofluorescence. In vivo, melittin enhanced motor functions, diminished infarction, fostered blood flow restoration in ischemic brain regions, and markedly inhibited the expression of inflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor-α, and nuclear factor-κB). In vitro, melittin augmented MCPIP1 expression in LPS-induced BV-2 cells and ameliorated inflammation-induced cell death. The neuroprotective effect conferred by melittin was attenuated upon MCPIP1 knockdown. Our findings establish that melittin-induced tolerance to ischemic injury is intrinsically linked with its anti-inflammatory capacity. Moreover, MCPIP1 is, at the very least, partially implicated in this process.

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.

A simple self-assembling system of melittin for hepatoma treatment

Background

Hepatoma is a serious public health concern. New attempts are urgently needed to solve this problem. Melittin, a host defense peptide derived from the venom of honeybees, has noteworthy hemolysis and non-specific cytotoxicity in clinical applications. Here, the self-assembly of melittin and vitamin E-succinic acid-(glutamate)12 (VG) was fabricated via noncovalent π-stacking and hydrogen bonding interactions using an environment-friendly method without “toxic” solvents.

Results

As expected, the designed self-assembly (denoted as M/VG nanoparticles) exhibits a uniform morphology with a particle size of approximately 60 nm and a zeta potential of approximately − 26.8 mV. Furthermore, added VG significantly decreased hemolytic activity, increased tumor-targeted effects, and accelerated apoptosis.

Conclusion

Our research provides a promising strategy for the development of natural self-assembled biological peptides for clinical application, particularly for transforming toxic peptides into safe therapeutic systems.

Graphical Abstract

Genetically engineered nano-melittin vesicles for multimodal synergetic cancer therapy

Melittin, the principal constituent in bee venom, is an attractive candidate for cancer therapy. However, its clinical applications are limited by hemolysis, nonspecific cytotoxicity, and rapid metabolism. Herein, a novel genetically engineered vesicular antibody-melittin (VAM) drug delivery platform was proposed and validated for targeted cancer combination therapy. VAM generated from the cellular plasma membrane was bio-synthetically fabricated, with the recombinant protein (hGC33 scFv-melittin) being harbored and displayed on the cell membrane. The bioactive and targetable nanomelittin conjugated by hGC33 scFv could be released in an MMP14-responsive manner at tumor sites, which reduced off-target toxicity, especially the hemolytic activity of melittin. Importantly, VAM could be loaded with small-molecule drugs or nanoparticles for combination therapy. Nanomelittin formed pores in membranes and disturbed phospholipid bilayers, which allowed the anticancer agents (i.e., chemotherapeutic drug doxorubicin and sonosensitizer purpurin 18 nanoparticles) co-delivered by VAM to penetrate deeper tumor sites, leading to synergistic therapeutic effects. In particular, the punching effect generated by sonodynamic therapy further improved the immunomodulatory effect of nanomelittin to activate the immune response. Taken together, our findings indicate that clinically translatable VAM-based strategies represent a universal, promising approach to multimodal synergetic cancer therapy.

Effect of CM15 on Supported Lipid Bilayer Probed by Atomic Force Microscopy

Antimicrobial peptides are key components of the immune system. These peptides affect the membrane in various ways; some form nano-sized pores, while others only produce minor defects. Since these peptides are increasingly important in developing antimicrobial drugs, understanding the mechanism of their interactions with lipid bilayers is critical. Here, using atomic force microscopy (AFM), we investigated the effect of a synthetic hybrid peptide, CM15, on the membrane surface comprising E. coli polar lipid extract. Direct imaging of supported lipid bilayers exposed to various concentrations of the peptide revealed significant membrane remodeling. We found that CM15 interacts with supported lipid bilayers and forms membrane-spanning defects very quickly. It is found that CM15 is capable of remodeling both leaflets of the bilayer. For lower CM15 concentrations, punctate void-like defects were observed, some of which re-sealed themselves as a function of time. However, for CM15 concentrations higher than 5 µM, the defects on the bilayers became so widespread that they disrupted the membrane integrity completely. This work enhances the understanding of CM15 interactions with the bacterial lipid bilayer.

Melittin as a safe compound to BALB/c mice immune system; a tiered approach immunotoxicity screening

BACKGROUND

Maintenance of immune system integrity is a vital requirement to protect human body against pathogens/cancers. Natural compounds have long been used due to their benefits for the immune system. One of which is bee venom that contains a peptide called melittin having antimicrobial and anticancer effects. Since a limited number of studies regarding the effects of melittin on the immune system have been carried out, we aimed to evaluate the effects of melittin on BALB/c mice immune system parameters.

METHODS

Female BALB /c mice were treated intraperitoneally (i.p) with 0.75 and 1.5 mg/kg doses of melittin for 14 days (5 doses per week). The negative control group received i.p normal saline whereas the positive controls received i.p 20 mg/kg cyclophosphamide (CYP). Immunological parameters such as hematological parameters, delayed-type hypersensitivity (DTH), hemagglutination titer (HA), spleen cellularity, splenocytes proliferation, as well as spleen and bone marrow histopathological assessment were evaluated.

RESULTS

Our findings showed that melittin has no gross pathological effect on the spleen and bone marrow. It was also demonstrated that melittin has no any significant effect on hematological parameters. Melittin did not cause any significant changes to proliferation response of splenocytes to PHA and LPS, spleen cellularity, DTH response, as well as the production of anti-SRBC antibodies. According to our results, melittin at 0.75 and 1.5 mg/kg doses could not induce significant changes on immune parameters and as a result, melittin was found to be safe for the mice immune system.

An Updated Review Summarizing the Anticancer Efficacy of Melittin from Bee Venom in Several Models of Human Cancers

Apitherapy (using bee products) has gained broad recognition in cancer therapeutics globally. Honeybee venom has a broad range of biological potential, and its utilization is rapidly emerging in apitherapy. Bee products have significant potential to strengthen the immune system and improve human health. Thus, this review is targeted toward recapitulating the chemo-preventive potential of melittin (MEL), which constitutes a substantial portion of honeybee venom. Honeybee venom (apitoxin) is produced in the venom gland of the honeybee abdomen, and adult bees utilize it as a primary colony defense mechanism. Apitoxin comprises numerous biologically active compounds, including peptides, enzymes, amines, amino acids, phospholipids, minerals, carbohydrates, and volatile components. We are mainly focused on exploring the potential of melittin (a peptide component) of bee venom that has shown promising potential in the treatment of several human cancers, including breast, stomach, lung, prostate, ovary, kidney, colon, gastric, esophageal, cervical cancers, melanoma, osteosarcoma, and hepatocellular carcinoma. This review has summarized all potential studies related to the anticancerous efficacy of melittin (apitoxin), its formulations, conjugates, and nano-formulations against several human carcinomas, which would further pave the way for future researchers in developing potent drugs for cancer management.

Molecularly Imprinted Chalcone-Branched Polyimide-Based Chemosensors with Stripe Nanopatterns for the Detection of Melittin

In this study, a chalcone-branched polyimide (CB-PI) was synthesized by the Steglich esterification reaction for selective recognition of the toxic peptide melittin (MEL). MEL was immobilized on a nanopatterned poly(dimethylsiloxane) (PDMS) mold using a conventional surface modification technique to increase binding sites. A stripe-nanopatterned thin CB-PI film was formed on a quartz crystal (QC) substrate by simultaneously performing microcontact printing and ultraviolet (UV) light dimerization using a MEL-immobilized mold. The surface morphology changes and dimensions of the molecularly imprinted polymer (MIP) films with stripe nanopatterns (S-MIP) were analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensing signals (Δf and Qe) of the S-MIP sensor were investigated upon adsorption in a 100-μL dilute plasma solution containing 30 μg/mL MEL, and its reproducibility, reuse, stability, and durability were investigated. The S-MIP sensor showed high sensitivity (5.49 mL/mg) and coefficient of determination (R2 = 0.999), and the detection limit (LOD) and the quantification limit (LOQ) were determined as 0.3 and 1.1 μg/mL, respectively. In addition, the selectivity coefficients (k*) calculated from the selectivity tests were 2.7-5.7, 2.1-4.3, and 2.8-4.6 for bovine serum albumin (BSA), immunoglobulin G (IgG), and apamin (APA), respectively. Our results indicate that the nanopatterned MIP sensors based on CB-PI demonstrate great potential as a sensing tool for the quantitative analysis of biomolecules.

Structures of calmodulin-melittin complexes show multiple binding modes lacking classical anchoring interactions

Calmodulin (CaM) is a Ca²⁺ sensor protein found in all eukaryotic cells that regulates a large number of target proteins in a Ca²⁺ concentration-dependent manner. As a transient type hub protein, it recognizes linear motifs of its targets, though for the Ca²⁺-dependent binding no consensus sequence was identified. Its complex with melittin, a major component of bee venom, is often used as a model system of protein - protein complexes. Yet, the structural aspects of the binding are not well understood, as only diverse, low-resolution data are available concerning the association. We present the crystal structure of melittin in complex with Ca²⁺-saturated calmodulins from two, evolutionarily distant species, Homo sapiens and Plasmodium falciparum representing three binding modes of the peptide. Results - augmented by molecular dynamics simulations - indicate that multiple binding modes can exist for CaM-melittin complexes, as an intrinsic characteristic of the binding. While the helical structure of melittin remains, swapping of its salt bridges and partial unfolding of its C-terminal segment can occur. In contrast to the classical way of target recognition by CaM, we found that different sets of residues can anchor at the hydrophobic pockets of CaM, which were considered as main recognition sites. Finally, the nanomolar binding affinity of the CaM-melittin complex is created by an ensemble of arrangements of similar stability - tight binding is achieved not by optimized specific interactions but by simultaneously satisfying less optimal interaction patterns in co-existing different conformers.

Melittin inhibits the proliferation migration and invasion of HCC cells by regulating ADAMTS9-AS2 demethylation

BACKGROUND

Melittin (MEL) has been reported to exhibit anti-cancer effects in vitro against several types of cancer. Long non-coding RNA (lncRNA) ADAMTS9-AS2 can be used as a tumor suppressor. However, there is insufficient data on the potential link between MEL and ADAMTS9-AS2 in hepatocellular carcinoma (HCC).

METHODS

RT-qPCR, CCK-8, colony formation, scratch wound healing and transwell assays were used to detect the function of MEL or ADAMTS9-AS2 on HCC cells. Furthermore, Western blot analysis was applied to determine that whether an association existed in MEL or ADAMTS9-AS2 with the PI3K/AKT/mTOR signal pathway. In addition, RT-qPCR and Western blot analysis validated that whether MEL has a demethylation effect.

RESULTS

All the experimental data showed that MEL or ADAMTS9-AS2 inhibited the proliferation, migration and invasion of MHCC97-H and HepG2 cells, which may relate to PI3K/AKT/mTOR signal pathway. Moreover, the result showed that MEL treatment inhibited the expression of DNA methyltransferase protein-1 (DNMT1), which acted as the role of demethylation, and then up-regulated the expression of ADAMTS9-AS2, affecting the development of HCC.

CONCLUSIONS

ADAMTS9-AS2 played a role in MEL-induced HCC inhibition. This study provided an interesting theoretical basis and further evidence for the potential application of MEL in the treatment of HCC.

Dual Cytotoxic Responses Induced by Treatment of A549 Human Lung Cancer Cells with Sweet Bee Venom in a Dose-Dependent Manner

Objectives

Sweet bee venom (sBV) is purified from Apis mellifera, containing a high level of melittin-its main component. It has been used as a therapeutic agent for pain relief and anti-inflammation, as well as for treating neuronal abnormalities. Recently, there have been studies on the therapeutic application of sBV for anticancer treatment. In the present study, we investigated the pharmacological effect of sBV treatment in A549 human lung cancer cells.

Methods

We used microscopic analysis to observe the morphological changes in A549 cells after sBV treatment. The MTT assay was used to examine the cytotoxic effect after dose-dependent sBV treatment. Molecular changes in sBV were evaluated by the expression of apoptosis marker proteins using western blot analysis.

Results

Microscopic analysis suggested that the growth inhibitory effect occurred in a dose-dependent manner; however, cell lysis occurred at a concentration over 20 μg/mL of sBV. The MTT assay indicated that sBV treatment exhibited a growth inhibitory effect at a concentration over 5 μg/mL. On fluorescence activated cell sorting analysis, G0 dead cells were observed after G1 arrest at treatment concentrations up to 10 μg/mL. However, rapid cell rupture was observed at a concentration of 20 μg/mL. Western blot analysis demonstrated that sBV treatment modulated the expression of multiple cell death-related proteins, including cleaved-PARP, cleaved-caspase 9, p53, Bcl2, and Bax.

Conclusion

sBV induced cell death in A549 human lung cancer cells at a pharmacological concentration, albeit causing hemolytic cell death at a high concentration.

Enhanced Therapeutic Effect of Optimized Melittin-dKLA, a Peptide Agent Targeting M2-like Tumor-Associated Macrophages in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is characterized by a high possibility of metastasis. M2-like tumor-associated macrophages (TAMs) are the main components of the tumor microenvironment (TME) and play a key role in TNBC metastasis. Therefore, TAMs may be a potential target for reducing TNBC metastasis. Melittin-dKLA, a peptide composed of fused melittin and pro-apoptotic peptide d(KLAKLAK)2 (dKLA), showed a potent therapeutic effect against cancers by depleting TAMs. However, melittin has a strong adverse hemolytic effect. Hence, we attempted to improve the therapeutic potential of melittin-dKLA by reducing toxicity and increasing stability. Nine truncated melittin fragments were synthesized and examined. Of the nine peptides, the melittin-dKLA8-26 showed the best binding properties to M2 macrophages and discriminated M0/M1/M2. All fragments, except melittin, lost their hemolytic effects. To increase the stability of the peptide, melittin-dKLA8-26 fragment was conjugated with PEGylation at the amino terminus and was named PEG-melittin-dKLA8-26. This final drug candidate was assessed in vivo in a murine TNBC model and showed superior effects on tumor growth, survival rates, and lung metastasis compared with the previously used melittin-dKLA. Taken together, our study showed that the novel PEG-melittin-dKLA8-26 possesses potential as a new drug for treating TNBC and TNBC-mediated metastasis by targeting TAMs.

The Pharmacological Potential of Novel Melittin Variants from the Honeybee and Solitary Bees against Inflammation and Cancer

The venom of honeybees is composed of numerous peptides and proteins and has been used for decades as an anti-inflammatory and anti-cancer agent in traditional medicine. However, the bioactivity of specific biomolecular components has been evaluated for the predominant constituent, melittin. So far, only a few melittin-like peptides from solitary bee species have been investigated, and the molecular mechanisms of bee venoms as therapeutic agents remain largely unknown. Here, the preclinical pharmacological activities of known and proteo-transcriptomically discovered new melittin variants from the honeybee and more ancestral variants from phylogenetically older solitary bees were explored in the context of cancer and inflammation. We studied the effects of melittin peptides on cytotoxicity, second messenger release, and inflammatory markers using primary human cells, non-cancer, and cancerous cell lines. Melittin and some of its variants showed cytotoxic effects, induced Ca²⁺ signaling and inhibited cAMP production, and prevented LPS-induced NO synthesis but did not affect the IP3 signaling and pro-inflammatory activation of endothelial cells. Compared to the originally-described melittin, some phylogenetically more ancestral variants from solitary bees offer potential therapeutic modalities in modulating the in vitro inflammatory processes, and hindering cancer cell viability/proliferation, including aggressive breast cancers, and are worth further investigation.

Pharmacological effects and mechanisms of bee venom and its main components: Recent progress and perspective

Bee venom (BV), a type of defensive venom, has been confirmed to have favorable activities, such as anti-tumor, neuroprotective, anti-inflammatory, analgesic, anti-infectivity effects, etc. This study reviewed the recent progress on the pharmacological effects and mechanisms of BV and its main components against cancer, neurological disorders, inflammatory diseases, pain, microbial diseases, liver, kidney, lung and muscle injury, and other diseases in literature during the years 2018–2021. The related target proteins of BV and its main components against the diseases include Akt, mTOR, JNK, Wnt-5α, HIF-1α, NF-κB, JAK2, Nrf2, BDNF, Smad2/3, AMPK, and so on, which are referring to PI3K/Akt/mTOR, MAPK, Wnt/β-catenin, HIF-1α, NF-κB, JAK/STAT, Nrf2/HO-1, TrkB/CREB/BDNF, TGF-β/Smad2/3, and AMPK signaling pathways, etc. Further, with the reported targets, the potential effects and mechanisms on diseases were bioinformatically predicted via Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, disease ontology semantic and enrichment (DOSE) and protein-protein interaction (PPI) analyses. This review provides new insights into the therapeutic effects and mechanisms of BV and its main components on diseases.

Profiling hymenopteran venom toxins: Protein families, structural landscape, biological activities, and pharmacological benefits

Hymenopterans are an untapped source of venom secretions. Their recent proteo-transcriptomic studies have revealed an extraordinary pool of toxins that participate in various biological processes, including pain, paralysis, allergic reactions, and antimicrobial activities. Comprehensive and clade-specific campaigns to collect hymenopteran venoms are therefore needed. We consider that data-driven bioprospecting may help prioritise sampling and alleviate associated costs. This work established the current protein landscape from hymenopteran venoms to evaluate possible sample bias by studying their origins, sequence diversity, known structures, and biological functions. We collected all 282 reported hymenopteran toxins (peptides and proteins) from the UniProt database that we clustered into 21 protein families from the three studied clades - wasps, bees, and ants. We identified 119 biological targets of hymenopteran toxins ranging from pathogen membranes to eukaryotic proteases, ion channels and protein receptors. Our systematic study further extended to hymenopteran toxins' therapeutic and biotechnological values, where we revealed promising applications in crop pests, human infections, autoimmune diseases, and neurodegenerative disorders.

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The hymenopteran toxin diversity includes 21 protein families from 81 species.

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Some toxins are shared across wasps, bees and ants, others are clade-specific.

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Their venoms contain membrane-active peptides, neurotoxins, allergens and enzymes.

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Hymenopteran toxins have been tested against a total of 119 biological targets.

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Hymenopteran toxins were predominantly evaluated as anti-infective agents.

The bee venom active compound melittin protects against bicuculline-induced seizures and hippocampal astrocyte activation in rats

Epilepsy is a chronic neuropathology characterized by an abnormal hyperactivity of neurons that generate recurrent, spontaneous, paradoxical and synchronized nerve impulses, leading or not to seizures. This neurological disorder affects around 70 million individuals worldwide. Pharmacoresistance is observed in about 30% of the patients and long-term use of antiepileptics may induce serious side effects. Thus, there is an interest in the study of the therapeutic potential of bioactive substances isolated from natural products in the treatment of epilepsy. Arthropod venoms contain neurotoxins that have high affinity for molecular structures in the neural tissue such as receptors, transporters and ion channels both in glial and neuronal membranes. This study evaluated the potential neuroprotective effect of melittin (MEL), an active compound of bee venom, in the bicuculline-induced seizure model (BIC) in rats. Male Wistar rats (3 months, 250-300 g) were submitted to surgery for the implantation of a unilateral cannula in the lateral ventricle. After the recovery period, rats received a microinjection of saline solution or MEL (0.1 mg per animal). Firstly, rats were evaluated in the open field (20 min) and in the elevated plus maze (5 min) tests after received microinjection of saline or MEL. After, 30 min later animals received BIC (100 mg/ml) or saline, and their behaviors were analyzed for 20 min in the open field according to a seizure scale. At the end, rats were euthanized, brains collected and processed to glial fibrillary acidic protein (GFAP) immunohistochemistry evaluation. No changes were observed in MEL-treated rats in the open field and elevated plus maze. However, 90% of MEL-treated animals were protected against seizures induced by BIC. There was an increase in the latency for the onset of seizures, accompanied by a reduction of GFAP-immunoreactivity cells in the dentate gyrus and CA1. Thus, our study suggests that MEL has an anticonvulsant potential, and further studies are needed to elucidate the mechanisms involved in this action.

Development of an Icariin-Loaded Bilosome-Melittin Formulation with Improved Anticancer Activity against Cancerous Pancreatic Cells

Pancreatic cancer currently represents a severe issue for the entire world. Therefore, much effort has been made to develop an effective treatment against it. Emerging evidence has shown that icariin, a flavonoid glycoside, is an effective anti-pancreatic cancer drug. Melittin, as a natural active biomolecule, has also shown to possess anticancer activities. In the present study, with the aim to increase its effectiveness against cancerous cells, icariin-loaded bilosome-melittin (ICA-BM) was developed. For the selection of an optimized ICA-BM, an experimental design was implemented, which provided an optimized formulation with a particle size equal to 158.4 nm. After estimation of the release pattern, the anti-pancreatic cancer efficacy of this new formulation was evaluated. The MTT assay was employed for the determination of half maximal inhibitory concentration (IC50), providing smaller IC50 for ICA-BM (2.79 ± 0.2 µM) compared to blank-BM and ICA-Raw (free drug) against PNAC1, a human pancreatic cancer cell line isolated from a pancreatic carcinoma of ductal cell origin. Additionally, cell cycle analysis for ICA-BM demonstrated cell arrest at the S-phase and pre-G1 phase, which indicated a pro-apoptotic behavior of the new developed formulation. The pro-apoptotic and anti-proliferative activity of the optimized ICA-BM against PNAC1 cells was also demonstrated through annexin V staining as well as estimation of caspase-3 and p53 protein levels. It can be concluded that the optimized ICA-BM formulation significantly improved the efficacy of icariin against cancerous pancreatic cells.

Microneedle-mediated transdermal nanodelivery systems: a review

The greatest limitation in the development of transdermal drug delivery systems is that only a few drugs can permeate the skin due to the barrier function of the stratum corneum. Active and passive methods are generally available for improving the ability of drug transdermal delivery. However, nanoparticles, as a passive approach, exhibit capacity-constrained permeation enhancement. Thus, microneedle-mediated nanoparticles possess enormous potential and broad prospects. Microneedles promote the penetration of macromolecules by creating microchannels on the skin surface. In this review, the prevailing subknowledge on microneedles (mechanism, classification, and applications of microneedles combined with nanoparticles) is discussed to provide a guideline for readers and a basic reference for further in-depth studies of this novel drug delivery system.

Hyaluronic Acid Coating Reduces the Leakage of Melittin Encapsulated in Liposomes and Increases Targeted Delivery to Melanoma Cells

Melittin is a promising antitumor substance; however, it is a nonspecific cytolytic peptide, which limits its clinical application. In this study, melittin liposomes (Mel-Lip) and hyaluronic acid (HA)-modified Mel-Lip (Mel-HA-Lip) were designed to reduce the toxicity and increase the anti-tumor effects of melittin. The optimal preparation procedure was evaluated using a uniform design based on the single factor method, and the concentration of HA was determined based on the cellular uptake of coumarin 6 labeled HA-Lip. Liposomes and HA-modified liposomes were evaluated in vitro by assessing cytotoxicity, cellular uptake, and release behavior. Liposomes prepared in the optimum formulation improved stability, with a particle size of 132.7 ± 1.55 nm, zeta potential of −11.5 ± 1.51 mV, entrapment efficiency of 86.25 ± 1.28%, and drug-loading efficiency of 3.91 ± 0.49%. Cellular uptake tests revealed that the uptake of nanoparticles significantly increased with HA modification, suggesting that HA modification enhanced the internalization of liposomes within cells, which was consistent with the results of the cytotoxicity analysis. Furthermore, in vitro release experiments showed that Mel-HA-Lip possessed a stronger sustained-release effect compared with Mel-Lip. The results of this experiment provide insight into the potential tumor-targeting effects of melittin.

Utilisation of compounds from venoms in drug discovery

Difficult drug targets are becoming the normal course of business in drug discovery, sometimes due to large interacting surfaces or only small differences in selectivity regions. For these, a different approach is merited: compounds lying somewhere between the small molecule and the large antibody in terms of many properties including stability, biodistribution and pharmacokinetics. Venoms have evolved over millions of years to be complex mixtures of stable molecules derived from other somatic molecules, the stability comes from the pressure to be ready for delivery at a moment's notice. Snakes, spiders, scorpions, jellyfish, wasps, fish and even mammals have evolved independent venom systems with complex mixtures in their chemical arsenal. These venom-derived molecules have been proven to be useful tools, such as for the development of antihypotensive angiotensin converting enzyme (ACE) inhibitors and have also made successful drugs such as Byetta® (Exenatide), Integrilin® (Eptifibatide) and Echistatin. Only a small percentage of the available chemical space from venoms has been investigated so far and this is growing. In a new era of biological therapeutics, venom peptides present opportunities for larger target engagement surface with greater stability than antibodies or human peptides. There are challenges for oral absorption and target engagement, but there are venom structures that overcome these and thus provide substrate for engineering novel molecules that combine all desired properties. Venom researchers are characterising new venoms, species, and functions all the time, these provide great substrate for solving the challenges presented by today's difficult targets.

Bee Venom Components as Therapeutic Tools against Prostate Cancer

Prostate cancer is one of the most common cancers in men. Despite the development of a variety of therapeutic agents to treat either metastatic hormone-sensitive prostate cancer, advanced prostate cancer, or nonmetastatic/metastatic castration-resistant prostate cancer, the progression or spread of the disease often cannot be avoided. Additionally, the development of resistance of prostate cancer cells to available therapeutic agents is a well-known problem. Despite extensive and cost-intensive research over decades, curative therapy for metastatic prostate cancer is still not available. Therefore, additional therapeutic agents are still needed. The animal kingdom offers a valuable source of natural substances used for the treatment of a variety of diseases. Bee venom of the honeybee is a mixture of many components. It contains proteins acting as enzymes such as phospholipase A2, smaller proteins and peptides such as melittin and apamin, phospholipids, and physiologically active amines such as histamine, dopamine, and noradrenaline. Melittin has been shown to induce apoptosis in different cancer cell lines, including prostate cancer cell lines. It also influences cell proliferation, angiogenesis, and necrosis as well as motility, migration, metastasis, and invasion of tumour cells. Hence, it represents an interesting anticancer agent. In this review article, studies about the effect of bee venom components on prostate cancer cells are discussed. An electronic literature research was performed utilising PubMed in February 2021. All scientific publications, which examine this interesting subject, are discussed. Furthermore, the different types of application of these promising substances are outlined. The studies clearly indicate that bee venom or melittin exhibited anticancer effects in various prostate cancer cell lines and in xenografts. In most of the studies, a combination of bee venom or the modified melittin with another molecule was utilised in order to avoid side effects and, additionally, to target selectively the prostate cancer cells or the surrounding tissue. The studies showed that systemic side effects and unwanted damage to healthy tissue and organs could be minimised when the anticancer drug was not activated until binding to the cancer cells or the surrounding tissue. Different targets were used, such as the matrix metalloproteinase 2, hormone receptors expressed by prostate cancer cells, the extracellular domain of PSMA, and the fibroblast activation protein occurring in the stroma of prostate cancer cells. Another approach used loaded phosphate micelles, which were cleaved by the enzyme secretory phospholipase A2 produced by prostate cancer cells. In a totally different approach, targeted nanoparticles containing the melittin gene were used for prostate cancer gene therapy. By the targeted nonviral gene delivery, the gene encoding melittin was delivered to the prostate cancer cells without systemic side effects. This review of the scientific literature reveals totally different approaches using bee venom, melittin, modified melittin, or protoxin as anticancer agents. The toxic agents acted through several different mechanisms to produce their anti-prostate cancer effects. These mechanisms are not fully understood yet and more experimental studies are necessary to reveal the complete mode of action. Nevertheless, the researchers have conducted pioneering work. Based on these results, further experimental and clinical studies about melittin and modifications of this interesting agent deriving from nature are necessary and could possibly lead to a complementary treatment option for prostate cancer.

Anti-PD-1 Immunotherapy and Bee Venom for Relapsed and Refractory Liposarcoma: A Case Report

Cancer immunotherapies, including immune checkpoint inhibitors, elicit long-term clinical responses but many cancer patients do not respond. Intensive efforts are therefore underway to identify additional immune pathways that may be modulated to enhance the efficacy of existing immunotherapies. Bee venom strongly stimulates the immune system, and is used as a complementary therapy to treat cancer pain in patients with advanced tumors in China. Bee venom contains several allergenic protease inhibitors and peptides. It triggers hypersensitivity reactions; that is, it is an immune system agonist. The generation of a spontaneous T cell response against tumor-associated antigens requires innate immune activation; this drives type I interferon production. We report a patient with a relapsed and refractory liposarcoma who had undergone several operations, chemotherapies, and radiotherapies. The tumor was large. The patient had attained the maximum radiation exposure dose. The tumor was resistant to chemotherapy and was infiltrating the pericardium, lungs, and diaphragm. The patient was a poor candidate for resection. He thus received apitherapy (a combination of bee venom and acupuncture) to control pain; then apatinib (an anti-angiogenic drug) was given to inhibit tumor growth but was terminated early because the patient could not tolerate the side effects. Subsequently, a programmed death 1 inhibitor was combined with apitherapy. Bee venom served as an innate immune system agonist promoting immune cell priming and recruitment in the tumor microenvironment. The patient was finally able to undergo radical liposarcoma resection, and no evidence of recurrence was found at re-examination 16 months after surgery.

Melittin inhibits lung metastasis of human osteosarcoma: Evidence of wnt/β-catenin signaling pathway participation

Melittin is a major active peptide component of bee venom that has been demonstrated to show anti-tumor effects. Osteosarcoma is a type of bone tumor with a high degree of malignancy, and metastasis is the main challenge of osteosarcoma therapy. This study aimed to investigate the role of melittin in the lung metastasis of osteosarcoma. 143 B cells were treated with different concentrations of melittin in vitro. Wound-healing and transwell assays were performed to determine the cell migration and invasion potential. Quantitative real-time PCR and Western blot experiments were performed to evaluate the expression levels of Wnt/β-catenin signaling pathway-related factors after treatment with melittin. The orthotopic implantation model and hematoxylin-eosin staining were used to investigate the effect of melittin treatment on tumor formation and lung metastasis. Immunohistochemical staining and Western blot experiments were performed to indicate the melittin-mediated expression changes in Wnt/β-catenin signaling pathway-related factors. The cell migration and invasion potential were observed to be inhibited in a dose-dependent manner upon treatment with melittin. Treatment with medium and high concentrations of melittin attenuated the mRNA and protein expression of LRP5, β-catenin, MMP-2, cyclin D, c-Myc, survivin, MMP-9, and VEGF genes in vitro. Melittin significantly inhibited the growth of tibia xenografts in nude mice and decreased the number of lung metastatic nodules. Consistent with the results observed in vitro, treatment with melittin at medium and high concentrations attenuated the expression of Wnt/β-catenin signaling pathway-related factors in vivo. In vitro, Wnt/β-catenin signaling pathway was involved in Melittin-mediated -migration and invasion potential of 143 B cells. Similarly, as observed in the in vivo experiments, Wnt/β-catenin signaling pathway was also associated with the role of melittin on lung metastasis of osteosarcomas.

Melittin sensitizes skin squamous carcinoma cells to 5-fluorouracil by affecting cell proliferation and survival

Combined 5-fluorouracil (5-FU) and melittin (MEL) is believed to enhance cytotoxic effects on skin squamous cell carcinoma (SCC). However, the rationale underlying cytotoxicity is fundamentally important for a proper design of combination chemotherapy, and to provide translational insights for future therapeutics in the dermatology field. The aim was to elucidate the effects of 5-FU/MEL combination on the viability, proliferation and key structures of human squamous cell carcinoma (A431). Morphology, plasma membrane, DNA, mitochondria, oxidative stress, cell viability, proliferation and cell death pathways were targeted for investigation by microscopy, MTT, trypan blue assay, flow cytometry and real-time cell analysis. 5-FU/MEL (0.25 µM/0.52 µM) enhanced the cytotoxic effect in A431 cells (74.46%, p < .001) after 72 h exposure, showing greater cytotoxic effect when compared to each isolated compound (45.55% 5-FU and 61.78% MEL). The results suggest that MEL induces plasma membrane alterations that culminate in a loss of integrity at subsequent times, sensitizing the cell to 5-FU action. DNA fragmentation, S and G2/M arrest, disruption of mitochondrial metabolism, and alterations in cell morphology culminated in proliferation blockage and apoptosis. 5-FU/MEL combination design optimizes the cytotoxic effects of each drug at lower concentrations, which may represent an innovative strategy for SCC therapy.

Cytotoxic and Pro-Apoptotic Effects of a Sub-Toxic Concentration of Fluvastatin on OVCAR3 Ovarian Cancer Cells After its Optimized Formulation to Melittin Nano-Conjugates

Fluvastatin (FLV) is a hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor often used to lower total and low-density lipoprotein (LDL) cholesterol and for the prevention of adverse cardiovascular events. This drug as well as melittin (MEL), the major component of honeybee venom (Apis mellifera), has shown antineoplastic activity, then representing promising approaches for cancer therapy. However, adverse effects related to the use of FLV and MEL have been reported and very few studies have been carried out to obtain an optimized formulation allowing for combining the two drugs and then maximizing the anticancer activity, then minimizing the needed dosage. In the present study, an optimized formulation in terms of minimized particle size and maximized zeta potential was investigated for its cytotoxic potential in human OVCAR3 ovarian cancer cells. FLV-MEL nano-conjugates, containing a sub-toxic concentration of drug, demonstrated an improved cytotoxic potential (IC50 = 2.5 µM), about 18-fold lower, compared to the free drug (IC50 = 45.7 µM). Cell cycle analysis studies demonstrated the significant inhibition of the OVCAR3 cells proliferation exerted by FLV-MEL nano-conjugates compared to all the other treatments, with a higher percentage of cells accumulating on G2/M and pre-G1 phases, paralleled by lower percentage of cells in G0/G1 and S phases. The synergistic antineoplastic activity of FLV and MEL combined in the optimized formula was also showed by the marked pronecrotic and pro-apoptotic activities, the latter mediated by the modulation of BAX/BCL-2 ratio in favor of BAX. Our optimized FLV-MEL formulation might therefore represents a novel path for the development of specific and more effective antineoplastic drugs directed against ovarian cancer.

Zoopharmacology: A Way to Discover New Cancer Treatments

Zoopharmacognosy is the multidisciplinary approach of the self-medication behavior of many kinds of animals. Recent studies showed the presence of antitumoral secondary metabolites in some of the plants employed by animals and their use for the same therapeutic purposes in humans. Other related and sometimes confused term is Zootherapy, which consists on the employment of animal parts and/or their by-products such as toxins, venoms, etc., to treat different human ailments. Therefore, the aim of this work is to provide a brief insight for the use of Zoopharmacology (comprising Zoopharmacognosy and Zootherapy) as new paths to discover drugs studying animal behavior and/or using compounds derived from animals. This work is focused on the approaches related to cancer, in order to propose a new promising line of research to overcome multidrug resistance (MDR). This novel subject will encourage the use of new alternative prospective ways to find new medicines.

Melittin-A Natural Peptide from Bee Venom Which Induces Apoptosis in Human Leukaemia Cells

Bee venom is a very complex mixture produced and secreted by the honeybee (Apis mellifera). Melittin is a major component of bee venom that accounts for about 52% of its dry mass. A vast number of studies have been dedicated to the effects of melittin’s regulation of apoptosis and to the factors that induce apoptosis in various types of cancer such as breast, ovarian, prostate, lung. The latest evidence indicates its potential as a therapeutic agent in the treatment of leukaemia. The aim of our present study is to evaluate melittin’s ability to induce apoptosis in leukaemia cell lines of different origin acute lymphoblastic leukaemia (CCRF-CEM) and chronic myelogenous leukaemia (K-562). We demonstrated that melittin strongly reduced cell viability in both leukaemia cell lines but not in physiological peripheral blood mononuclear cells (PMBCs). Subsequent estimated parameters (mitochondrial membrane potential, Annexin V binding and Caspases 3/7 activity) clearly demonstrated that melittin induced apoptosis in leukaemia cells. This is a very important step for research into the development of new potential anti-leukaemia as well as anticancer therapies. Further analyses on the molecular level have been also planned (analysis of proapoptotic genes expression and DNA damages) for our next research project, which will also focus on melittin.

Potential Therapeutic Applications of Bee Venom on Skin Disease and Its Mechanisms: A Literature Review

Skin is larger than any other organ in humans. Like other organs, various bacterial, viral, and inflammatory diseases, as well as cancer, affect the skin. Skin diseases like acne, atopic dermatitis, and psoriasis often reduce the quality of life seriously. Therefore, effective treatment of skin disorders is important despite them not being life-threatening. Conventional medicines for skin diseases include corticosteroids and antimicrobial drugs, which are effective in treating many inflammatory and infectious skin diseases; however, there are growing concerns about the side effects of these therapies, especially during long-term use in relapsing or intractable diseases. Hence, many researchers are trying to develop alternative treatments, especially from natural sources, to resolve these limitations. Bee venom (BV) is an attractive candidate because many experimental and clinical reports show that BV exhibits anti-inflammatory, anti-apoptotic, anti-fibrotic, antibacterial, antiviral, antifungal, and anticancer effects. Here, we review the therapeutic applications of BV in skin diseases, including acne, alopecia, atopic dermatitis, melanoma, morphea, photoaging, psoriasis, wounds, wrinkles, and vitiligo. Moreover, we explore the therapeutic mechanisms of BV in the treatment of skin diseases and killing effects of BV on skin disease-causing pathogens, including bacteria, fungi and viruses.