Melittin, a major peptide component of bee venom, and its conjugates in cancer therapy

Melittin-The principal toxin of honeybee venom-Is also produced in the honeybee fat body

Melittin is a powerful toxin present in honeybee venom that is active in a wide range of animals, from insects to humans. Melittin exerts numerous biological, toxicological, and pharmacological effects, the most important of which is destruction of the cell membrane. The phospholipase activity of melittin and its ability to activate phospholipases in the venom contribute to these actions. Using analytical methods, we discovered that the honeybee Apis mellifera produces melittin not only in the venom gland but also in its fat body cells, which remain resistant to this toxin's effects. We suggest that melittin acts as an anti-bacterial agent, since its gene expression is significantly upregulated when honeybees are infected with Escherichia coli and Listeria monocytogenes bacteria; additionally, melittin effectively kills these bacteria in the disc diffusion test. We hypothesize that the chemical and physicochemical properties of the melittin molecule (hydrophilicity, lipophilicity, and capacity to form tetramers) in combination with reactive conditions (melittin concentration, salt concentration, pH, and temperature) are responsible for the targeted destruction of bacterial cells and apparent tolerance towards own tissue cells. Considering that melittin is an important current and, importantly, potential broad-spectrum medication, a thorough understanding of the observed phenomena may significantly increase its use in clinical practice.

Melittin inactivates YAP/HIF-1α pathway via up-regulation of LATS2 to inhibit hypoxia-induced proliferation, glycolysis and angiogenesis in NSCLC

BACKGROUND

NSCLC is one of the most common causes of death. The hypoxia microenvironment contributes to cancer progression. The purpose was to explore the effects and mechanism of melittin on NSCLC cells in the hypoxic microenvironment.

METHODS

NSCLC cell lines (A549 and H1299) were cultured in normoxia or hypoxia conditions with or without melittin treatment. The viability of the cells was detected via MTT assay and the proliferation ability was evaluated by EdU assay. QRT-PCR was performed to evaluate GLUT1, LDHA, HK2, VEGF and LATS2 mRNA levels. Glucose transport was assessed by the 2-NBDG uptake assay. The angiogenesis was determined by the tubule formation assay. The protein expressions of GLUT1, LDHA, HK2, VEGF, LATS2, YAP, p-YAP and HIF-1α were detected via western blotting assay. The tumor formation assay was conducted to examine the roles of melittin and LATS2 in vivo.

RESULTS

Melittin inhibited hypoxia-induced cell viability, proliferation, glycolysis and angiogenesis as well as suppressed YAP binding to HIF-1α in NSCLC. Melittin inactivated the YAP/HIF-1α pathway via up-regulation of LATS2, ultimately inhibiting cancer progression of NSCLC. Moreover, melittin suppressed tumor growth via up-regulation of LATS2 in vivo.

CONCLUSION

Melittin inactivated the YAP/HIF-1α pathway via up-regulation of LATS2 to contribute to the development of NSCLC. Therefore, melittin is expected to become a potential prognostic drug for the therapy of NSCLC.

Analysis of risk factors for acute kidney injury in children with severe wasp stings

BACKGROUND

Acute kidney injury (AKI) is common in children with sepsis, chronic kidney disease, poisoning or other conditions. Wasp stings are recognized as an important etiology. Several retrospective studies have investigated AKI after wasp stings in adults, but research on children remains limited.

METHODS

The study included 48 children with multiple organ dysfunction syndrome after wasp stings. Demographic data, clinical manifestations, laboratory findings, management and clinical outcomes were collected, and analyzed to identify early indicators or risk factors for AKI.

RESULTS

20 children (41.7%) developed AKI, and 28 (58.3%) did not. Serum creatine levels elevated mostly within 24 h from stings in children with AKI (16/20, 80%). Compared with non-AKI group, AKI group exhibited more cases with cola-colored urine, jaundice, and had higher sting numbers/body surface area (BSA) and higher revised sequential organ failure assessment scores (rSOFA) as well as higher levels of C-reactive protein (CRP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), lactate dehydrogenase (LDH), troponin (cTnI), creatine kinase (CK), and longer prothrombin time (PT). Both univariable and multivariable logistic regression analysis identified cola-colored urine as a potential early risk factor for AKI.

CONCLUSIONS

The AKI group exhibited higher sting numbers/BSA, higher levels of CRP, ALT, AST, TBIL, LDH, cTnI, and CK, as well as longer PT (p < 0.05). Our findings also suggest that cola-colored urine may serve as an early indicator or potential risk factor for AKI after wasp stings in children, which is very easy to identify for first aiders or pediatricians.

Evaluating the cytotoxicity mechanism of the cell-penetrating peptide TP10 on Jurkat cells

TP10, a classic cell-penetrating peptide, shows a high degree of similarity to AMPs in structure. Although TP10 has been widely used in drug delivery, the mechanism underlying its cytotoxicity is yet to be elucidated. Herein, we explored the cell-killing mechanism of TP10 against human leukemia Jurkat cells. TP10 induced necrosis in Jurkat cells via rapid disruption of cell membranes, particularly at high concentrations. Although mitochondria in Jurkat cells were damaged by TP10, mitochondria-mediated apoptosis did not occur, possibly due to intracellular ATP depletion. Necroptosis in TP10-treated Jurkat cells became an alternative route of apoptosis. Our results demonstrate that necrosis and necroptosis rather than apoptosis are involved in the cell-killing mechanism of TP10, which contributes to the understanding of its toxicity.

Control of artificial membrane fusion in physiological ionic solutions beyond the limits of electroformation

Membrane fusion, merging two lipid bilayers, is crucial for fabricating artificial membrane structures. Over the past 40 years, in contrast to precise and controllable membrane fusion in-vivo through specific molecules such as SNAREs, controlling the fusion in-vitro while fabricating artificial membrane structures in physiological ionic solutions without fusion proteins has been a challenge, becoming a significant obstacle to practical applications. We present an approach consisting of an electric field and a few kPa hydraulic pressure as an additional variable to physically control the fusion, enabling tuning of the shape and size of the 3D freestanding lipid bilayers in physiological ionic solutions. Mechanical model analysis reveals that pressure-induced parallel/normal tensions enhance fusion among membranes in the microwell. In-vitro peptide-membrane assay, mimicking vesicular transport via pressure-assisted fusion, and stability of 38 days with in-chip pressure control via pore size-regulated hydrogel highlight the potential for diverse biological applications.

Ame-miR-1-3p of bee venom reduced cell viability through the AZIN1/OAZ1-ODC1-polyamines pathway and enhanced the defense ability of honeybee (Apis mellifera L.)

Bee venom serves as an essential defensive weapon for bees and also finds application as a medicinal drug. MicroRNAs (miRNAs) serve as critical regulators and have been demonstrated to perform a variety of biological functions. However, the presence of miRNAs in bee venom needs to be confirmed. Therefore, we conducted small RNA sequencing and identified 158 known miRNAs, 15 conserved miRNAs and 4 novel miRNAs. It is noteworthy that ame-miR-1-3p, the most abundant among them, accounted for over a quarter of all miRNA reads. To validate the function of ame-miR-1-3p, we screened 28 candidate target genes using transcriptome sequencing and three target gene prediction software (miRanda, PITA and TargetScan) for ame-miR-1-3p. Subsequently, we employed real-time quantitative reverse transcription PCR (qRT-PCR), Western blot and other technologies to confirm that ame-miR-1-3p inhibits the relative expression of antizyme inhibitor 1 (AZIN1) by targeting the 3' untranslated region (UTR) of AZIN1. This, in turn, caused ODC antizyme 1 (OAZ1) to bind to ornithine decarboxylase 1 (ODC1) and mark ODC1 for proteolytic destruction. The reduction in functional ODC1 ultimately resulted in a decrease in polyamine biosynthesis. Furthermore, we determined that ame-miR-1-3p accelerates cell death through the AZIN1/OAZ1-ODC1-polyamines pathway. Our studies demonstrate that ame-miR-1-3p diminishes cell viability and it may collaborate with sPLA2 to enhance the defence capabilities of honeybees (Apis mellifera L.). Collectively, these data further elucidate the defence mechanism of bee venom and expand the potential applications of bee venom in medical treatment.

Hive Products: Composition, Pharmacological Properties, and Therapeutic Applications

Beekeeping provides products with nutraceutical and pharmaceutical characteristics. These products are characterized by abundance of bioactive compounds. For different reasons, honey, royal jelly, propolis, venom, and pollen are beneficial to humans and animals and could be used as therapeutics. The pharmacological action of these products is related to many of their constituents. The main bioactive components of honey include oligosaccharides, methylglyoxal, royal jelly proteins (MRJPs), and phenolics compounds. Royal jelly contains jelleins, royalisin peptides, MRJPs, and derivatives of hydroxy-decenoic acid, particularly 10-hydroxy-2-decenoic acid (10-HDA), which possess antibacterial, anti-inflammatory, immunomodulatory, neuromodulatory, metabolic syndrome-preventing, and anti-aging properties. Propolis has a plethora of activities that are referable to compounds such as caffeic acid phenethyl ester. Peptides found in bee venom include phospholipase A2, apamin, and melittin. In addition to being vitamin-rich, bee pollen also includes unsaturated fatty acids, sterols, and phenolics compounds that express antiatherosclerotic, antidiabetic, and anti-inflammatory properties. Therefore, the constituents of hive products are particular and different. All of these constituents have been investigated for their properties in numerous research studies. This review aims to provide a thorough screening of the bioactive chemicals found in honeybee products and their beneficial biological effects. The manuscript may provide impetus to the branch of unconventional medicine that goes by the name of apitherapy.

Inhibition of proteinase-activated receptor 2 (PAR2) decreased the malignant progression of lung cancer cells and increased the sensitivity to chemotherapy

OBJECTIVES

This study aimed to study the effect of protease-activated receptor 2 (PAR2) on the proliferation, invasion, and clone formation of lung cancer cells. It also aimed to evaluate the inhibitory effect of melittin on PAR2 and the anti-lung cancer effect of melittin combined with gefitinib.

METHODS

The correlation between the co-expression of PAR2 and epithelial-mesenchymal transition (EMT) markers was analyzed. PAR2 in A549 and NCI-H1299 cells was knocked down using siRNA. MTT assay, Transwell assay, and colony formation assay were used to detect the effects of PAR2 on cell proliferation, invasion, and clone formation. The anti-cancer effect of PAR2 knockdown on gefitinib treatment was analyzed. The synergistic effect of melittin on gefitinib treatment by inhibiting PAR2 and the underlying molecular mechanism were further analyzed and tested.

RESULTS

The expression of PAR2 was upregulated in lung cancer, which was associated with the poor prognosis of lung cancer. PAR2 knockdown inhibited the stemness and EMT of lung cancer cells. It also inhibited the proliferation, invasion, and colony formation of A549 and NCI-H1299 cells. Moreover, PAR2 knockdown increased the chemotherapeutic sensitivity of gefitinib in lung cancer. Melittin inhibited PAR2 and the malignant progression of lung cancer cells. Melittin increased the chemotherapeutic sensitivity of gefitinib in lung cancer by inhibiting PAR2.

CONCLUSION

PAR2 may promote the proliferation, invasion, and colony formation of lung cancer cells by promoting EMT. Patients with a high expression of PAR2 have a poor prognosis. Inhibition of PAR2 increased the chemotherapeutic sensitivity of gefitinib. PAR2 may be a potential therapeutic target and diagnostic marker for lung cancer.

Immunomodulatory activities and biomedical applications of melittin and its recent advances

Melittin (MLT), a peptide containing 26 amino acids, is a key constituent of bee venom. It comprises ∼40%-60% of the venom's dry weight and is the main pricing index for bee venom, being the causative factor of pain. The unique properties of MLT extracted from bee venom have made it a very valuable active ingredient in the pharmaceutical industry as this cationic and amphipathic peptide has propitious effects on human health in diverse biological processes. It has the ability to strongly impact the membranes of cells and display hemolytic activity with anticancer characteristics. However, the clinical application of MLT has been limited by its severe hemolytic activity, which poses a challenge for therapeutic use. By employing more efficient mechanisms, such as modifying the MLT sequence, genetic engineering, and nano-delivery systems, it is anticipated that the limitations posed by MLT can be overcome, thereby enabling its wider application in therapeutic contexts. This review has outlined recent advancements in MLT's nano-delivery systems and genetically engineered cells expressing MLT and provided an overview of where the MLTMLT's platforms are and where they will go in the future with the challenges ahead. The focus is on exploring how these approaches can overcome the limitations associated with MLT's hemolytic activity and improve its selectivity and efficacy in targeting cancer cells. These advancements hold promise for the creation of innovative and enhanced therapeutic approaches based on MLT for the treatment of cancer.

The Synthetic Antimicrobial Peptide Derived From Melittin Displays Low Toxicity and Anti-infectious Properties

The low stability and nonspecific toxicity are the main limiting factors for the clinical applications of melittin (MLT). This study aimed to design and synthesize new analogs of MLT to increase stability, reduce toxicity, and retain their antimicrobial properties against bacterial pathogens. At first, peptide analogs were designed computationally by inducing single mutations in MLT peptides and evaluating their physicochemical properties. The stability of the analogs with the highest scores was determined by Gromacs software. In vitro assays were performed to examine the antimicrobial activity and toxicity of the selected analogs. Two peptide analogs, M1 and M2, were selected based on the SVM score in cell PPD. The M1 analog was created by replacing alanine with leucine on the 15th. The M2 analog was designed by substituting alanine with leucine and isoleucine with arginine at the 15th and 17th positions. According to the Gromacs results, the M2 peptide indicated more stability. RMSD and RMSF results showed no undesirable fluctuations during the 200 ns MD simulation. The MIC and MBC values for the M1 peptide were calculated in a range of 8-128 μg/ml, while the M2 peptide limited the bacterial growth to 32-128 μg/mL. Both peptides indicated less toxicity than natural MLT, based on MTT assay results. The hemolytic activity of the M1 analog was more than M2 at 16 μg/mL concentration. M1 peptide displayed the highest selectivity index against S. aureus and A. baumannii, which were approximately 5.27-fold improvements compared to MLT. In conclusion, we introduced two analogs of MLT with low toxicity, low hemolytic activity, and higher stability, along with retaining antimicrobial properties against gram-negative and positive bacteria.

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.

Highly in vitro anti-cancer activity of melittin-loaded niosomes on non-small cell lung cancer cells

BACKGROUND

Development of promising medicines from natural sources, specially venom, is of highly necessitated to combat against life-threatening cancers. Non-small cell lung cancer (NSCLC) has a significant percentage of mortalities. Melittin, from bee venom, is a potent anticancer peptide but its toxicity has limited its therapeutic applications. Accordingly, this study aims to synthesize niosomes with suitable stability and capacity for carrying melittin as a drug. Additionally, it seeks to evaluate the anti-cancer activity of melittin-loaded niosomes on non-small cell lung cancer.

METHODS

The niosome was prepared by thin film hydration method. Cytotoxicity and apoptosis were assessed on A549, Calu-3, and MRC5 cells. Real-time PCR was used to determine expression of apoptotic and pro-apoptotic Bax, Bcl2, and Casp3 genes. Immunocytochemistry (ICC) was also used to confirm expression of the abovementioned genes. Furthermore, wound healing assay was performed to compare inhibition effects of melittin-loaded niosomes with free melittin on migration of cancer cells.

RESULTS

IC50 values of melittin-loaded niosomes for A549, Calu-3, and MRC5 cells were respectively 0.69 μg/mL, 1.02 μg/mL, and 2.56 μg/mL after 72 h. Expression level of Bax and Casp3 increased '10 and 8' and '9 and 10.5' fold in A549 and Calu-3, whereas Bcl2 gene expression decreased 0.19 and 0.18 fold in the mentioned cell lines. The cell migration inhibited by melittin-loaded niosomes.

CONCLUSIONS

Melittin-loaded niosomes had more anti-cancer effects and less toxicity on normal cells than free melittin. Furthermore, it induced apoptosis and inhibited cancer cells migration. Our results showed that melittin-loaded niosomes may be a drug lead and it has the potential to be future developed for lung cancer treatment.

1 H-NMR revealed pyruvate as a differentially abundant metabolite in the venom glands of Apis cerana and Apis mellifera

As a common defense mechanism in Hymenoptera, bee venom has complex components. Systematic and comprehensive analysis of bee venom components can aid in early evaluation, accurate diagnosis, and protection of organ function in humans in cases of bee stings. To determine the differences in bee venom composition and metabolic pathways between Apis cerana and Apis mellifera, proton nuclear magnetic resonance (1 H-NMR) technology was used to detect the metabolites in venom samples. A total of 74 metabolites were identified and structurally analyzed in the venom of A. cerana and A. mellifera. Differences in the composition and abundance of major components of bee venom from A. cerana and A. mellifera were mapped to four main metabolic pathways: valine, leucine and isoleucine biosynthesis; glycine, serine and threonine metabolism; alanine, aspartate and glutamate metabolism; and the tricarboxylic acid cycle. These findings indicated that the synthesis and metabolic activities of proteins or polypeptides in bee venom glands were different between A. cerana and A. mellifera. Pyruvate was highly activated in 3 selected metabolic pathways in A. mellifera, being much more dominant in A. mellifera venom than in A. cerana venom. These findings indicated that pyruvate in bee venom glands is involved in various life activities, such as biosynthesis and energy metabolism, by acting as a precursor substance or intermediate product.

Effect of animal venom toxins on the main links of the homeostasis of mammals (Review)

The human body is affected by environmental factors. The dynamic balance between the organism and its environment results from the influence of natural, anthropogenic and social aspects. The factors of exogenous origin determine development of adaptive changes. The present article summarises the mechanisms of animal venom toxins and homeostasis disruption in the body of mammals. The mechanisms underlying pathological changes are associated with shifts in biochemical reactions. Components of the immune, nervous and endocrine systems are key in the host defense and adaptation processes in response to venom by triggering signalling pathways (PI3kinase pathway, arachidonic acid cascade). Animal venom toxins initiate the development of inflammatory processes, the synthesis of pro-inflammatory mediators (cytokines), ROS, proteolytic enzymes, activate the migration of leukocytes and macrophages. Keratinocytes and endothelial cells act as protective barriers under the action of animal venom toxins on the body of mammals. In addition, the formation of pores in cell membranes, structural changes in cell ion channels are characteristic of the action of animal venom toxins.

Design of pH-responsive antimicrobial peptide melittin analog-camptothecin conjugates for tumor therapy

Melittin, a classical antimicrobial peptide, is a highly potent antitumor agent. However, its significant toxicity seriously hampers its application in tumor therapy. In this study, we developed novel melittin analogs with pH-responsive, cell-penetrating and membrane-lytic activities by replacing arginine and lysine with histidine. After conjugation with camptothecin (CPT), CPT-AAM-1 and CPT-AAM-2 were capable of killing tumor cells by releasing CPT at low concentrations and disrupting cell membranes at high concentrations under acidic conditions. Notably, we found that the C-terminus of the melittin analogs was more suitable for drug conjugation than the N-terminus. CPT-AAM-1 significantly suppressed melanoma growth in vivo with relatively low toxicity. Collectively, the present study demonstrates that the development of antitumor drugs based on pH-responsive antimicrobial peptide-drug conjugates is a promising strategy.

Curvature sensing of curvature-inducing proteins with internal structure

Many types of peripheral and transmembrane proteins can sense and generate membrane curvature. Laterally isotropic proteins and crescent proteins with twofold rotational symmetry, such as Bin/Amphiphysin/Rvs superfamily proteins, have been studied theoretically. However, proteins often have an asymmetric structure or a higher rotational symmetry. We studied theoretically the curvature sensing of proteins with asymmetric structures and structural deformations. First, we examined proteins consisting of two rodlike segments. When proteins have mirror symmetry, their sensing ability is similar to that of single-rod proteins; hence, with increasing protein density on a cylindrical membrane tube, a second- or first-order transition occurs at a middle or small tube radius, respectively. As asymmetry is introduced, this transition becomes a continuous change and metastable states appear at high protein densities. Protein with threefold, fivefold, or higher rotational symmetry has laterally isotropic bending energy. However, when a structural deformation is allowed, the protein can have a preferred orientation and stronger curvature sensing.

New N-Terminal Fatty-Acid-Modified Melittin Analogs with Potent Biological Activity

Melittin, a natural antimicrobial peptide, has broad-spectrum antimicrobial activity. This has resulted in it gaining increasing attention as a potential antibiotic alternative; however, its practical use has been limited by its weak antimicrobial activity, high hemolytic activity, and low proteolytic stability. In this study, N-terminal fatty acid conjugation was used to develop new melittin-derived lipopeptides (MDLs) to improve the characteristics of melittin. Our results showed that compared with native melittin, the antimicrobial activity of MDLs was increased by 2 to 16 times, and the stability of these MDLs against trypsin and pepsin degradation was increased by 50 to 80%. However, the hemolytic activity of the MDLs decreased when the length of the carbon chain of fatty acids exceeded 10. Among the MDLs, the newly designed analog Mel-C8 showed optimal antimicrobial activity and protease stability. The antimicrobial mechanism studied revealed that the MDLs showed a rapid bactericidal effect by interacting with lipopolysaccharide (LPS) or lipoteichoic acid (LTA) and penetrating the bacterial cell membrane. In conclusion, we designed and synthesized a new class of MDLs with potent antimicrobial activity, high proteolytic stability, and low hemolytic activity through N-terminal fatty acid conjugation.

Glutamate affects self-assembly, protein corona, and anti-4 T1 tumor effects of melittin/vitamin E-succinic acid-(glutamate)n nanoparticles

Melittin (M) has attracted increasing attention for its significant antitumor effects and various immunomodulatory effects. However, various obstacles such as the short plasma half-life and adverse reactions restrict its application. This study aimed to systematically investigate the self-assembly mechanism, components of the protein corona, targeting behavior, and anti-4 T1 tumor effect of vitamin E-succinic acid-(glutamate)n /melittin nanoparticles with varying amounts of glutamic acid. Here, we present a new vitamin E-succinic acid-(glutamate)5 (E5), vitamin E-succinic acid-(glutamate)10 (E10) or vitamin E-succinic acid-(glutamate)15 (E15), and their co-assembly system with positively charged melittin in water. The molecular dynamics simulations demonstrated that the electrostatic energy and van der Waals force in the system decreased significantly with the increase in the amount of glutamic acid. The melittin and E15 system exhibited the optimal stability for nanoparticle self-assembly. When nanoparticles derived from different self-assembly systems were co-incubated with plasma from patients with breast cancer, the protein corona showed heterogeneity. In vivo imaging demonstrated that an increase in the number of glutamic acid residues enhanced circulation duration and tumor-targeting effects. Both in vitro and in vivo antitumor evaluation indicated a significant increase in the antitumor effect with the addition of glutamic acid. According to our research findings, the number of glutamic acid residues plays a crucial role in the targeted delivery of melittin for immunomodulation and inhibition of 4 T1 breast cancer. Due to the self-assembly capabilities of vitamin E-succinic acid-(glutamate)n in water, these nanoparticles carry significant potential for delivering cationic peptides such as melittin.

Melittin as an Activator of the Autophagy and Unfolded Protein Response Pathways in Colorectal HCT116 Cell Line

Background

The potential anticancer effect of melittin has motivated scientists to find its exact molecular mechanism of action. There are few data on the effect of melittin on the UPR and autophagy as two critical pathways involved in tumorigenesis of colorectal and drug resistance. This study aimed to investigate the effect of melittin on these pathways in the colorectal cancer (CRC) HCT116 cells.

Methods

MTT method was carried out to assess the cytotoxicity of melittin on the HCT116 cell line for 24, 48, and 72 h. After selecting the optimal concentrations and treatment times, the gene expression of autophagy flux markers (LC3-βII and P62) and UPR markers (CHOP and XBP-1s) were determined using qRT-PCR. The protein level of autophagy initiation marker (Beclin1) was also determined by Western blotting.

Results

MTT assay showed a cytotoxic effect of melittin on the HCT116 cells. The increase in LC3-βII and decrease in P62 mRNA expression levels, along with the elevation in the Beclin1 protein level, indicated the stimulatory role of melittin on the autophagy. Melittin also significantly enhanced the CHOP and XBP-1s expressions at mRNA level, suggesting the positive role of the melittin on the UPR activation.

Conclusion

This study shows that UPR and autophagy can potentially be considered as two key signaling pathways in tumorigenesis, which can be targeted by the BV melittin in the HCT116 cells. Further in vivo evaluations are recommended to verify the obtained results.

Hosts and Heterologous Expression Strategies of Recombinant Toxins for Therapeutic Purposes

The production of therapeutic recombinant toxins requires careful host cell selection. Bacteria, yeast, and mammalian cells are common choices, but no universal solution exists. Achieving the delicate balance in toxin production is crucial due to potential self-intoxication. Recombinant toxins from various sources find applications in antimicrobials, biotechnology, cancer drugs, and vaccines. "Toxin-based therapy" targets diseased cells using three strategies. Targeted cancer therapy, like antibody-toxin conjugates, fusion toxins, or "suicide gene therapy", can selectively eliminate cancer cells, leaving healthy cells unharmed. Notable toxins from various biological sources may be used as full-length toxins, as plant (saporin) or animal (melittin) toxins, or as isolated domains that are typical of bacterial toxins, including Pseudomonas Exotoxin A (PE) and diphtheria toxin (DT). This paper outlines toxin expression methods and system advantages and disadvantages, emphasizing host cell selection's critical role.

Investigation the effects of bee venom and H-dental-derived mesenchymal stem cells on non-small cell lung cancer cells (A549)

BACKGROUND

Lung cancer, one of the most common oncological diseases worldwide, continues to be the leading cause of cancer-related deaths. The development of new approaches for lung cancer, which still has a low survival rate despite medical advances, is of great importance.

METHODS AND RESULTS

In this study, bee venom (BV), conditioned medium of MSCs isolated from dental follicles (MSC-CM) and cisplatin were applied at different doses and their effects on A549 cell line were evaluated. Dental follicles were used as a source of MSCs source and differentiation kits, and characterization studies (flow cytometry) were performed. Cell viability was measured by the MTT method and apoptosis was measured by an Annexin V-FITC/PI kit on flow cytometer. IC50 dose values were determined according to the 24th hour and were determined as 15.8 µg/mL for BV, 10.78% for MSC-CM and 5.77 µg/mL for cisplatin. IC50 values found for BV and MSC-CM were also given in combination and the effects were observed. It was found that the applied substances caused BV to decrease in cell viability and induced apoptosis in cells. In addition to the induction of apoptosis in BV, MSC-CM, and combined use, all three applications led to an increase in Bax protein expression and a decrease in Bcl-2 protein expression. The molecular mechanism of anticancer activity through inhibition of Bax and Bcl-2 proteins and the NF-κB signaling pathway may be suggested.

CONCLUSION

Isolated MSCs in our study showed anticancer activity and BV and MSC-CM showed synergistic antiproliferative and apoptotic effects.

Melittin: a possible regulator of cancer proliferation in preclinical cell culture and animal models

BACKGROUND

Melittin is a water-soluble cationic peptide derived from bee venom that has been thoroughly studied for the cure of different cancers. However, the unwanted interactions of melittin produce hemolytic and cytotoxic effects that hinder their therapeutic applications. To overcome the shortcomings, numerous research groups have adopted different approaches, including conjugation with tumor-targeting proteins, gene therapy, and encapsulation in nanoparticles, to reduce the non-specific cytotoxic effects and potentiate their anti-cancerous activity.

PURPOSE

This article aims to provide mechanistic insights into the chemopreventive activity of melittin and its nanoversion in combination with standard anti-cancer drugs for the treatment of cancer.

METHODS

We looked over the pertinent research on melittin's chemopreventive properties in online databases such as PubMed and Scopus.

CONCLUSION

In the present article, the anti-cancerous effects of melittin on different cancers have been discussed very nicely, as have their possible mechanisms of action to act against different tumors. Besides, it interacts with different signal molecules that regulate the diverse pathways of cancerous cells, such as cell cycle arrest, apoptosis, metastasis, angiogenesis, and inflammation. We also discussed the recent progress in the synergistic combination of melittin with standard anti-cancer drugs and a nano-formulated version of melittin for targeted delivery to improve its anticancer potential.

Recent advances in melittin-based nanoparticles for antitumor treatment: from mechanisms to targeted delivery strategies

As a naturally occurring cytolytic peptide, melittin (MLT) not only exhibits a potent direct tumor cell-killing effect but also possesses various immunomodulatory functions. MLT shows minimal chances for developing resistance and has been recognized as a promising broad-spectrum antitumor drug because of this unique dual mechanism of action. However, MLT still displays obvious toxic side effects during treatment, such as nonspecific cytolytic activity, hemolytic toxicity, coagulation disorders, and allergic reactions, seriously hampering its broad clinical applications. With thorough research on antitumor mechanisms and the rapid development of nanotechnology, significant effort has been devoted to shielding against toxicity and achieving tumor-directed drug delivery to improve the therapeutic efficacy of MLT. Herein, we mainly summarize the potential antitumor mechanisms of MLT and recent progress in the targeted delivery strategies for tumor therapy, such as passive targeting, active targeting and stimulus-responsive targeting. Additionally, we also highlight the prospects and challenges of realizing the full potential of MLT in the field of tumor therapy. By exploring the antitumor molecular mechanisms and delivery strategies of MLT, this comprehensive review may inspire new ideas for tumor multimechanism synergistic therapy.

Melittin inhibits tumor cell migration and enhances cisplatin sensitivity by suppressing IL-17 signaling pathway gene LCN2 in castration-resistant prostate cancer

BACKGROUND

Melittin is a small molecule polypeptide extracted from the abdominal cavity of bees, which is used to treat inflammatory diseases and relieve pain. However, the antitumor effect of melittin and its mechanisms remain unclear, especially in castration-resistant prostate cancer (CRPC).

METHODS

Through CCK-8 assay, colony formation assay, wound healing assay and Transwell migration assay, we explored the effect of melittin on CRPC cell lines. In addition, with microarray analysis, gene ontology analysis and kyoto encyclopedia of genes and genomes analysis, this study identified key genes and signaling pathways that influence the growth of PC-3 cells. Meanwhile, the effect of melittin on CRPC was also verified through subcutaneous tumor formation experiments. Finally, we also tested the relevant indicators of human prostate cancer (PCa) specimens through immunohistochemistry and H＆E stating.

RESULTS

Here, melittin was verified to inhibit the cell proliferation and migration of CPRC. Moreover, RNA-sequence analysis demonstrated that Interleukin-17 (IL-17) signaling pathway gene Lipocalin-2 (LCN2) was downregulated by melittin treatment in CRPC. Further investigation revealed that overexpression of LCN2 was able to rescue tumor suppression and cisplatin sensitivity which melittin mediated. Interestingly, the expression of LCN2 is highly related to metastasis in PCa.

CONCLUSIONS

In brief, our study indicates that LCN2 plays an oncogenic role in CRPC and melittin may be selected as an attractive candidate for CRPC therapy.

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.

Antiviral attributes of bee venom as a possible therapeutic approach against SARS-CoV-2 infection

The unprecedented scale of the SARS-CoV-2 pandemic has driven considerable investigation into novel antiviral treatments since effective vaccination strategies cannot completely eradicate the virus. Apitherapy describes the medicinal use of bee venom, which may be an effective treatment against SARS-CoV-2 infection. Bee venom contains chemicals that are antimicrobial and stimulate the immune system to counteract viral load. The present review focuses on the use of bee venom as a possible treatment for COVID-19 and reviews studies on the pharmacodynamics of bee venom.

Engineered Histidine-Rich Peptides Enhance Endosomal Escape for Antibody-Targeted Intracellular Delivery of Functional Proteins

Currently, the clinical application of protein/peptide therapeutics is mainly limited to the modulation of diseases in extracellular spaces. Intracellular targets are hardly accessed, owing largely to the endosomal entrapment of internalized proteins/peptides. Here, we report a strategy to design and construct peptides that enable endosome-to-cytosol delivery based on an extension of the "histidine switch" principle. By substituting the Arg/Lys residues in cationic cell-penetrating peptides (CPPs) with histidine, we obtained peptides with pH-dependent membrane-perturbation activity. These peptides do not randomly penetrate cells like CPPs, but imitate the endosomal escape of CPPs following cellular uptake. Working with one such 16-residue peptide (hsLMWP) with high endosomal escape capacity, we engineered modular fusion proteins and achieved antibody-targeted delivery of diverse protein cargoes-including the pro-apoptotic protein BID (BH3-interacting domain death agonist) and Cre recombinase-into the cytosol of multiple cancer cell types. After extensive in vitro testing, an in vivo analysis with xenograft mice ultimately demonstrated that a trastuzumab-hsLMWP-BID fusion conferred strong anti-tumor efficacy without apparent side effects. Notably, our fusion protein features a modular design, allowing flexible applications for any antibody/cargo combination of choice. Therefore, the potential applications extend throughout life science and biomedicine, including gene editing, cancer treatment, and immunotherapy.

Recent Advances of Cell-Penetrating Peptides and Their Application as Vectors for Delivery of Peptide and Protein-Based Cargo Molecules

Peptides and proteins, two important classes of biomacromolecules, play important roles in the biopharmaceuticals field. As compared with traditional drugs based on small molecules, peptide- and protein-based drugs offer several advantages, although most cannot traverse the cell membrane, a natural barrier that prevents biomacromolecules from directly entering cells. However, drug delivery via cell-penetrating peptides (CPPs) is increasingly replacing traditional approaches that mediate biomacromolecular cellular uptake, due to CPPs' superior safety and efficiency as drug delivery vehicles. In this review, we describe the discovery of CPPs, recent developments in CPP design, and recent advances in CPP applications for enhanced cellular delivery of peptide- and protein-based drugs. First, we discuss the discovery of natural CPPs in snake, bee, and spider venom. Second, we describe several synthetic types of CPPs, such as cyclic CPPs, glycosylated CPPs, and D-form CPPs. Finally, we summarize and discuss cell membrane permeability characteristics and therapeutic applications of different CPPs when used as vehicles to deliver peptides and proteins to cells, as assessed using various preclinical disease models. Ultimately, this review provides an overview of recent advances in CPP development with relevance to applications related to the therapeutic delivery of biomacromolecular drugs to alleviate diverse diseases.

Can Bee Venom Be Used as Anticancer Agent in Modern Medicine?

Honey bee venom in its composition contains many biologically active peptides and enzymes that are effective in the fight against diseases of various etiologies. The history of the use of bee venom for medicinal purposes dates back thousands of years. There are many reports in the literature on the pharmacological properties of bee venom and/or its main components, e.g., anti-arthritic, anti-inflammatory, anti-microbial or neuroprotective properties. In addition, both crude venom and melittin exhibit cytotoxic activity against a wide range of tumor cells, with significant anti-metastatic activity in pre-clinical studies. Due to the constantly increasing incidence of cancer, the development of new therapeutic strategies in oncology is a particular challenge for modern medicine. A review paper discusses the various properties of bee venom with an emphasis on its anticancer properties. For this purpose, the PubMed database was searched, and publications related to "bee", "venom", "cancer" from the last 10 years were selected.

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.

Co-delivery of EGCG and melittin with self-assembled fluoro-nanoparticles for enhanced cancer therapy

PURPOSE

Melittin (MPI) is a potential anticancer peptide due to its abilities of antitumor and immunomodulatory functions. Epigallocatechin-3-Ogallate (EGCG), a major extract of green tea, has shown great affinity for various types of biological molecules, especially for peptide/protein drugs. The aim of this study is to prepare a fluoro- nanoparticle (NP) formed by self-assembly of fluorinated EGCG (FEGCG) and MPI, and evaluate the effect of fluorine modification on MPI delivery and their synergistic antitumor effect.

METHODS

Characterization of FEGCG@MPI NPs was determined by dynamic light scattering (DLS) and transmission electron microscope (TEM). Biology functions of FEGCG@MPI NPs were detected by hemolysis effect, cytotoxicity, apoptosis, cellular uptake with confocal microscopy and flow cytometry. The protein expression levels of Bcl-2/Bax, IRF, STATT-1, P-STAT-1, and PD-L1 were determined via western blotting. A transwell assay and wound healing assay were used to detect the cell migration and invasion. The antitumor efficacy of FEGCG@MPI NPs was demonstrated in a subcutaneous tumor model.

RESULTS

Fluoro-nanoparticles could be formed by self-assembly of FEGCG and MPI, and fluorine modification on EGCG could ameliorate the side effect and delivery of MPI. The promoted therapeutics of FEGCG@MPI NPs could be achieved by regulating PD-L1 and apoptosis signaling, which might involve pathways of IRF, STAT-1/pSTAT-1, PD-L1, Bcl-2, and Bax in vitro. Moreover, FEGCG@MPI NPs could significantly inhibit the growth of tumor in vivo.

CONCLUSIONS

FEGCG@MPI NPs may offer a potential platform and promising strategy in cancer therapy.

A combination of genetically engineered oncolytic virus and melittin-CpG for cancer viro-chemo-immunotherapy

BACKGROUND

Immunotherapy has emerged as an efficient therapeutic approach for cancer management. However, stimulation of host immune system against cancer cells often fails to achieve promising clinical outcomes mainly owing to the immunosuppressive characteristics of the tumor microenvironment (TME). Combination therapeutics that can trigger sustained immunogenic cell death (ICD) have provided new opportunities for cancer treatment.

METHODS

In this study, we designed and applied an ICD inducer regimen, including a genetically engineered oncolytic virus (miRNA-modified coxsackieviruses B3, miR-CVB3), a pore-forming lytic peptide (melittin, found in bee venom), and a synthetic toll-like receptor 9 ligand (CpG oligodeoxynucleotides), for breast cancer and melanoma treatment. We compared the anti-tumor efficacy of miR-CVB3 and CpG-melittin (CpGMel) alone and in combination (miR-CVB3 + CpGMel) and investigated possible mechanisms involved.

RESULTS

We demonstrated that miR-CVB3 + CpGMel had no major impact on viral growth, while enhancing the cellular uptake of CpGMel in vitro. We further showed that combination therapy led to significant increases in tumor cell death and release of damage-associated molecular patterns compared with individual treatment. In vivo studies in 4T1 tumor-bearing Balb/c mice revealed that both primary and distant tumors were significantly suppressed, and the survival rate was significantly prolonged after administration of miR-CVB3 + CpGMel compared with single treatment. This anti-tumor effect was accompanied by increased ICD and immune cell infiltration into the TME. Safety analysis showed no significant pathological abnormalities in Balb/c mice. Furthermore, the developed therapeutic regimen also demonstrated a great anti-tumor activity in B16F10 melanoma tumor-bearing C57BL/6 J mice.

CONCLUSIONS

Overall, our findings indicate that although single treatment using miR-CVB3 or CpGMel can efficiently delay tumor growth, combining oncolytic virus-based therapy can generate even stronger anti-tumor immunity, leading to a greater reduction in tumor size.

Insect Antimicrobial Peptides: Advancements, Enhancements and New Challenges

Several insects are known as vectors of a wide range of animal and human pathogens causing various diseases. However, they are also a source of different substances, such as the Antimicrobial Peptides (AMPs), which can be employed in the development of natural bioactive compounds for medical, veterinary and agricultural applications. It is well known that AMP activity, in contrast to most classical antibiotics, does not lead to the development of natural bacterial resistance, or at least the frequency of resistance is considered to be low. Therefore, there is a strong interest in assessing the efficacy of the various peptides known to date, identifying new compounds and evaluating possible solutions in order to increase their production. Moreover, implementing AMP modulation in insect rearing could preserve insect health in large-scale production. This review describes the current knowledge on insect AMPs, presenting the validated ones for the different insect orders. A brief description of their mechanism of action is reported with focus on proposed applications. The possible effects of insect diet on AMP translation and synthesis have been discussed.

Evolving strategies and application of proteins and peptide therapeutics in cancer treatment

Several proteins and peptides have therapeutic potential and can be used for cancer therapy. By binding to cell surface receptors and other indicators uniquely linked with or overexpressed on tumors compared to healthy tissue, protein biologics enhance the active targeting of cancer cells, as opposed to the passive targeting of cells by conventional small-molecule chemotherapeutics. This study focuses on peptide medications that exist to slow or stop tumor growth and the spread of cancer, demonstrating the therapeutic potential of peptides in cancer treatment. As an alternative to standard chemotherapy, peptides that selectively kill cancer cells while sparing healthy tissue are developing. A mountain of clinical evidence supports the efficacy of peptide-based cancer vaccines. Since a single treatment technique may not be sufficient to produce favourable results in the fight against cancer, combination therapy is emerging as an effective option to generate synergistic benefits. One example of this new area is the use of anticancer peptides in combination with nonpeptidic cytotoxic drugs or the combination of immunotherapy with conventional therapies like radiation and chemotherapy. This review focuses on the different natural and synthetic peptides obtained and researched. Discoveries, manufacture, and modifications of peptide drugs, as well as their contemporary applications, are summarized in this review. We also discuss the benefits and difficulties of potential advances in therapeutic peptides.

Mellitin peptide quantification in seasonally collected crude bee venom and its anticancer effects on myelogenous K562 human leukaemia cell line

BACKGROUND

Apitherapy is an emerging field in cancer research, particularly in developing communities. The potency of Melittin (MEL), a major constituent in bee venom is accounted for the cytotoxic capacity against cancer cells. It is postulated that the genotype of bees and the time of venom collection influences its specific activity against certain types of cancer.

METHOD

Hereby, Jordanian crude bee venom (JCBV) was collected during different seasons of the year, specifically spring, summer and autumn and investigated for in vitro antitumour effects. Venom collected during springtime comprised the highest quantity of MEL in comparison to venom collected some other time. Springtime-collected JCBV extract and MEL were tested on an immortal myelogenous leukaemia cell line, namely K562 leukemic cells. Treated cells were examined for cell modality via flow cytometry analysis and cell death mediating gene expressions.

RESULTS

Springtime-collected JCBV extract and MEL showed an IC₅₀ of 3.7 ± 0.37 μg/ml and 1.84 ± 0.75 μg/ml, respectively. In comparison to JCBV and positive control, MEL-treated cells exhibited late apoptotic death with a moderate cellular arrest at G0/G1 and an increase of cell number at G2/M phase. Expression of NF-κB/MAPK14 axis was inhibited in MEL and JCBV-treated cells, as well as expression of c-MYC and CDK4. Moreover, marked upregulation in ABL1, JUN and TNF was observed. In conclusion, springtime-collected JCBV showed the highest content of MEL while both JCBV and pure MEL showed apoptotic, necrotic, and cell cycle arrest efficiency against K562 leukemic cells.

CONCLUSION

Integration of bee venom in chemotherapy needs more investigation and should be carefully translated into clinical use. During such translation, the correlation of bee genotype, collection time and concentration of MEL in CBV should be profiled.

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.

Determination of the Effects of Bee Venom on Triple Negative Breast Cancer Cells in Vitro

Honeybees provide multiple products such as bee venom (BV) which are used for various nutritional and medicinal purposes. BV has received great attention due to its wide range of bioactive components with potential anti-cancer effects on different cancers. Triple negative breast cancer (TNBC) is defined as an aggressive type of breast cancer and new therapeutic targets are required for its treatment. In the current literature information is varied about the composition and quantity of BV bioactive compounds as well as the origin of BV and its significance. In this context, the cytotoxic and apoptotic effects of BV with a higher rate of mellitin from Apis mellifera anatoliaca (Muğla ecotype) on MDA-MB-231 cells was evaluated, in vitro. The cytotoxic, apoptotic and morphological effects of BV were determined by WST-1, Annexin V, cell cycle analysis and Acridine Orange staining. The results showed that BV caused apoptotic cell death in TNBC cells at a lower dose (0.47 μg/mL, p<0.01). This study suggests that BV could be developed as a potential therapeutic agent for cancer treatment. However, the mechanism of BV-induced apoptosis death should be clarified at the molecular level.

Therapeutic Use of Bee Venom and Potential Applications in Veterinary Medicine

Apitherapy is a branch of alternative medicine that consists of the treatment of diseases through products collected, processed, and secreted by bees, specifically pollen, propolis, honey, royal jelly, and bee venom. In traditional medicine, the virtues of honey and propolis have been well-known for centuries. The same, however, cannot be said for venom. The use of bee venom is particularly relevant for many therapeutic aspects. In recent decades, scientific studies have confirmed and enabled us to understand its properties. Bee venom has anti-inflammatory, antioxidant, central nervous system inhibiting, radioprotective, antibacterial, antiviral, and antifungal properties, among others. Numerous studies have often been summarised in reviews of the scientific literature that have focused on the results obtained with mouse models and their subsequent transposition to the human patient. In contrast, few reviews of scientific work on the use of bee venom in veterinary medicine exist. This review aims to take stock of the research achievements in this particular discipline, with a view to a recapitulation and stabilisation in the different research fields.

Application of injectable hydrogels in cancer immunotherapy

Immunotherapy is a revolutionary and promising approach to cancer treatment. However, traditional cancer immunotherapy often has the disadvantages of limited immune response rate, poor targeting, and low treatment index due to systemic administration. Hydrogels are drug carriers with many advantages. They can be loaded and transported with immunotherapeutic agents, chemical anticancer drugs, radiopharmaceuticals, photothermal agents, photosensitizers, and other therapeutic agents to achieve controlled release of drugs, extend the retention time of drugs, and thus successfully trigger anti-tumor effects and maintain long-term therapeutic effects after administration. This paper reviews recent advances in injectable hydrogel-based cancer immunotherapy, including immunotherapy alone, immunotherapy with combination chemotherapy, radiotherapy, phototherapy, and DNA hydrogel-based immunotherapy. Finally, we review the potential and limitations of injectable hydrogels in cancer immunotherapy.

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.

Pharmacological properties and therapeutic potential of honey bee venom

Honey bee venom (BV) is a valuable product, and has a wide range of biological effects, and its use is rapidly increasing in apitherapy. Therefore, the current study, we reviewed the existing knowledge about BV composition and its numerous pharmacological properties for future research and use. Honey bee venom or apitoxin is produced in the venom gland in the honey bee abdomen. Adult bees use it as a primary colony defense mechanism. It is composed of many biologically active substances including peptides, enzymes, amines, amino acids, phospholipids, minerals, carbohydrates as well as some volatile components. Melittin and phospholipase A₂ are the most important components of BV, having anti-cancer, antimicrobial, anti-inflammatory, anti-arthritis, anti-nociceptive and other curative potentials. Therefore, in medicine, BV has been used for centuries against different diseases like arthritis, rheumatism, back pain, and various inflammatory infections. Nowadays, BV or its components separately, are used for the treatment of various diseases in different countries as a natural medicine with limited side effects. Consequently, scientists as well as several pharmaceutical companies are trying to get a new understanding about BV, its substances and its activity for more effective use of this natural remedy in modern medicine.

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.

Key Genes Are Associated with the Prognosis of Glioma, and Melittin Can Regulate the Expression of These Genes in Glioma U87 Cells

Glioma is the most common primary tumor of the central nervous system. Currently, there is no effective treatment for glioma. Melittin (MT) is the main component of bee venom, which was found to have therapeutic effects on a variety of tumors. In this study, we explored the relationship between key genes regulated by MT and the prognosis of glioma. In cultured glioma U87 and U251 cells, MT inhibited cell proliferation and induces cell apoptosis in a time- and concentration-dependent manner. RNA-seq revealed that MT upregulated 11 genes and downregulated 37 genes. These genes are mainly enriched in cell membrane signaling pathways, such as surface membrane, membrane-enclosed organelles, integral component of membrane, PPAR signaling pathway, and voltage-gated potassium channel. PPI network analysis and literature analysis of 48 genes were performed, and 8 key genes were identified, and these key genes were closely associated with clinical prognosis. Overexpression of PCDH18, PPL, DEPP1, VASN, KCNE4, MYBPH, and C5AR2 genes or low expression of MARCH4 gene in glioma patients was associated with poor survival. qPCR confirmed that MT can regulate the expression of these genes in glioma U87 cells. This study indicated that MT significantly inhibited the growth and regulated the expression of PCDH18, C5AR2, VASN, DEPP1, MYBPH, KCNE4, PPL, and MARCH4 genes in glioma U87 cells in vitro. These genes are closely related to the prognosis of patients with glioma and can be used as independent prognostic factors in patients with glioma. MT is a potential drug for the treatment of glioma.

A network pharmacological approach to reveal the multidrug resistance reversal and associated mechanisms of acetogenins against colorectal cancer

Multidrug Resistance (MDR) in tumors is caused by the over-expression of ATP Binding Cassette transporter proteins such as Multidrug Resistance Protein 1 and Breast Cancer Resistance Protein 1. This in silico study focuses on identifying a MDR inhibitor among acetogenins (AGEs) of Annona muricata and also aims at predicting colorectal cancer (CRC) core targets of AGEs through a network pharmacological approach. Twenty-four AGEs were initially screened for their ADME properties. Molecular interaction studies were performed with the two proteins MRP1 and BCRP1. As the structure of MRP1 was not available, an inward-facing conformation of MRP1 was modeled. A Protein-protein interaction network was constructed for the correlating targets of CRC. KEGG pathway and Gene Ontology analysis were performed for the predicted CRC targets. We identified four lead AGEs: Muricatocin B, Annonacinone, Annonacin A and Annomuricin E having a higher binding affinity towards MDR proteins. MD simulation studies performed with the three lead AGEs and the MDR proteins showed that MRP1(DBD): Annomuricin E complex was stable throughout the simulation. Our analysis revealed ABCG2, ERBB2, STAT3, AR, SRC and ABCC1 as CRC targets of the lead molecules. The top 10 signaling pathways and functions of correlative CRC targets were also predicted. We conclude that the identified lead molecules might act as competitive inhibitors for reversing MDR in CRC. Additionally, network pharmacological studies established the correlative CRC targets and their mechanisms of action. Further experimental studies are needed to validate our findings. Communicated by Ramaswamy H. Sarma.

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.

Potentiality of raloxifene loaded melittin functionalized lipidic nanovesicles against pancreatic cancer cells

Pancreatic cancer (PC) frequency and incidence have grown rapidly in recent years. One of the most serious problems with PC is the existence of asymptotic manifestations, which frequently delays early detection, and until the diagnosis is established, tumor cells progress to the metastatic stage. Another significant concern with PC is the scarcity of well-defined pharmacotherapeutic drugs. The aim of this study was to develop an efficient nanocarrier system to augment the efficacy of raloxifene (RLX) against PC cells. As a result, the current investigation was carried out in order to give an effective treatment method, in which an optimum RLX loaded phospholipid-based vesicles with melittin (PL-MEL) was chosen using experimental design software, with particle size, zeta potential and entrapment efficiency % as dependent variables. Furthermore, anticancer activity against PANC1 cells was assessed. The optimized nanovesicle parameters were 172.5 nm for the measured size, zeta potential of -0.69 mV, and entrapment efficiency of 76.91% that were in good agreement with the expected ones. RLX-raw, plain formula, and optimized RLX-PL-MEL showed IC50 concentrations of 26.07 ± 0.98, 9.166 ± 0.34, and 1.24 ± 0.05 µg/mL, respectively. Furthermore, cell cycle analysis revealed that the nanovesicle was most effective in the G2-M phase, whereas Bax, and Bcl-2 estimates revealed that optimized RLX formula had the highest apoptotic activity among treatments investigated. However, as compared to RLX alone or plain formula alone, the optimized formula demonstrated higher expression of TNFα and Bax while a significant reduction of Bcl-2 and NF-κB expression was observed. mitochondrial membrane potential (MMP) analysis confirmed the apoptosis as well as the anticancer effect of the optimized formula. Thus, the present study results showed an improvement in the anti-PC effects of the RLX with phospholipid conjugated melittin, making it a novel treatment approach against PC.

Tachyplesin I and its derivatives: A pharmaco-chemical perspective on their antimicrobial and antitumor potential

INTRODUCTION

Increasing evidence suggests that intratumor microbiota are an intrinsic component in the tumor microenvironment across multiple cancer types, and that there is a close relationship between microbiota and tumor progression. Therefore, how to address the interaction between bacteria and malignances has become a growing concern. Tachyplesin I (TPI), a peptide with dual antimicrobial and antitumor effects, holds great promise as a therapeutic alternative for the aforementioned diseases, with the advantage of broad-spectrum activities, quick killing efficacy, and a low tendency to induce resistance.

AREAS COVERED

This review comprehensively summarizes the pharmacological mechanisms of TPI with an emphasis on its antimicrobial and antitumor potential. Furthermore, it presents advances in TPI derivatives and gives a perspective on their future development. The article is based on literature searches using PubMed and SciFinder to retrieve the most up-to-date information of TPI.

EXPERT OPINION

Bacterial infections and cancer both pose a serious threat to health due to their symbiotic interactions and drug resistance. TPI is anticipated to be a novel agent to control pathogenic bacteria and various tumors through multiple mechanisms of action. Indeed, the continuous advancements in chemical modification and innovative applications of TPI give hope for future improvements in therapeutic efficacy.

Melittin-solid phospholipid mixed films trigger amyloid-like nano-fibril arrangements at air-water interface

We used the Langmuir monolayers technique to study the surface properties of melittin toxin mixed with either liquid-condensed DSPC or liquid-expanded POPC phospholipids. Pure melittin peptide forms stable insoluble monolayers at the air-water interface without interacting with Thioflavin T (Th-T), a sensitive probe to detect protein amyloid formation. When melittin peptide is mixed with DSPC lipid at 50 % of peptide area proportion at the surface, we observed the formation of fibril-like structures detected by Brewster angle microscopy (BAM), but they were not observable with POPC. The nano-structures in the melittin-DSPC mixtures became Th-T positive labeling when the arrangement was observed with fluorescence microscopy. In this condition, Th-T undergoes an unexpected shift in the typical emission wavelength of this amyloid marker when a 2D fluorescence analysis is conducted. Even when reflectivity analysis of BAM imaging evidenced that these structures would correspond to the DSPC lipid component of the mixture, the interpretation of ATR-FTIR and Th-T data suggested that both components were involved in a new lipid-peptide rearrangement. These nano-fibril arrangements were also evidenced by scanning electron and atomic force microscopy when the films were transferred to a mica support. The fibril formation was not detected when melittin was mixed with the liquid-expanded POPC lipid. We postulated that DSPC lipids can dynamically trigger the process of amyloid-like nano-arrangement formation at the interface. This process is favored by the relative peptide content, the quality of the interfacial environment, and the physical state of the lipid at the surface.

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.