Synthesis of breast cancer targeting conjugate of temporin-SHa analog and its effect on pro- and anti-apoptotic protein expression in MCF-7 cells

Synthesis of Second-Generation Analogs of Temporin-SHa Peptide Having Broad-Spectrum Antibacterial and Anticancer Effects

Antimicrobial peptides (AMPs) are a promising class of therapeutic alternatives with broad-spectrum activity against resistant pathogens. Small AMPs like temporin-SHa (1) and its first-generation analog [G10a]-SHa (2) possess notable efficacy against Gram-positive and Gram-negative bacteria. In an effort to further improve this antimicrobial activity, second-generation analogs of 1 were synthesised by replacing the natural glycine residue at position-10 of the parent molecule with atypical amino acids, such as D-Phenylalanine, D-Tyrosine and (2-Naphthyl)-D-alanine, to study the effect of hydrophobicity on antimicrobial efficacy. The resultant analogs (3-6) emerged as broad-spectrum antibacterial agents. Notably, the [G10K]-SHa analog (4), having a lysine substitution, demonstrated a 4-fold increase in activity against Gram-negative (Enterobacter cloacae DSM 30054) and Gram-positive (Enterococcus faecalis DSM 2570) bacteria relative to the parent peptide (1). Among all analogs, [G10f]-SHa peptide (3), featuring a D-Phe substitution, showed the most potent anticancer activity against lung cancer (A549), skin cancer (MNT-1), prostate cancer (PC-3), pancreatic cancer (MiaPaCa-2) and breast cancer (MCF-7) cells, achieving an IC50 value in the range of 3.6-6.8 µM; however, it was also found to be cytotoxic against normal cell lines as compared to [G10K]-SHa (4). Peptide 4 also possessed good anticancer activity but was found to be less cytotoxic against normal cell lines as compared to 1 and 3. These findings underscore the potential of second-generation temporin-SHa analogs, especially analog 4, as promising leads to develop new broad-spectrum antibacterial and anticancer agents.

Release of a novel peptide from ferritin nanocages: A new tool for therapeutic applications

The development of new drug delivery systems for targeted chemotherapy release in cancer cells represents a very promising tool. In this contest, protein-based nanocages have considerable potential as drug delivery devices. Notably, ferritin has emerged as an excellent candidate due to its unique architecture, surface properties and high biocompatibility. A promising strategy might then involve ferritin cargos for specifical release of AntiMicrobial Peptides endowed with anticancer activity to cancer cells. In this paper, we encapsulated the TRIL analogue of Temporin-L peptide within a ferritin nanocage and evaluated the cargo biological properties. The results demonstrated a reduced haemolytic activity of the peptide and a selective cytotoxicity activity on cancer cells likely mediated by oxidative stress while having no effects on non-tumoral cells. The combination of the properties of ferritin with TRIL, might open up the way to the development of novel peptide delivery systems for future pharmaceutical applications.

Temporins: Multifunctional Peptides from Frog Skin

Temporins are short peptides secreted by frogs from all over the world. They exert antimicrobial activity, mainly against Gram-positive bacteria, including resistant pathogens; recent studies highlight other possible applications of these peptides as anticancer or antiviral agents. This review is meant to describe the main features of temporins produced by different ranid genera. Due to the abundance of published papers, we focus on the most widely investigated peptides. We report studies on their mechanism of action and three-dimensional structure in model systems mimicking bacterial membranes or in the presence of cells. The design and the antimicrobial activity of peptide analogues is also described, with the aim of highlighting elements that are crucial to improve the bioactivity of peptides while reducing their toxicity. Finally, a short section is dedicated to the studies aimed at applying these peptides as drugs, to produce new antimicrobial materials or in other technological uses.

Design, Synthesis and Characterization of [G10a]-Temporin SHa Dendrimers as Dual Inhibitors of Cancer and Pathogenic Microbes

As the technologies for peptide synthesis and development continue to mature, antimicrobial peptides (AMPs) are being widely studied as significant contributors in medicinal chemistry research. Furthermore, the advancement in the synthesis of dendrimers’ design makes dendrimers wonderful nanostructures with distinguishing properties. This study foregrounds a temporin SHa analog, [G10a]-SHa, and its dendrimers as globular macromolecules possessing anticancer and antibacterial activities. These architectures of temporin SHa, named as [G10a]-SHa, its dendrimeric analogs [G10a]₂-SHa and [G10a]₃-SHa, and [G10a]₂-SHa conjugated with a polymer molecule, i.e., Jeff-[G10a]₂-SHa, were synthesized, purified on RP-HPLC and UPLC and fully characterized by mass, NMR spectroscopic techniques, circular dichroism, ultraviolet, infrared, dynamic light scattering, and atomic force microscopic studies. In pH- and temperature-dependent studies, all of the peptide dendrimers were found to be stable in the temperature range up to 40–60 °C and pH values in the range of 6–12. Biological-activity studies showed these peptide dendrimers possessed improved antibacterial activity against different strains of both Gram-positive and Gram-negative strains. Together, these dendrimers also possessed potent selective antiproliferative activity against human cancer cells originating from different organs (breast, lung, prostate, pancreas, and liver). The high hemolytic activity of [G10a]₂-SHa and [G10a]₃-SHa dendrimers, however, limits their use for topical treatment, such as in the case of skin infection. On the contrary, the antibacterial and anticancer activities of Jeff-[G10a]₂-SHa, associated with its low hemolytic action, make it potentially suitable for systemic treatment.

Serum Stable and Low Hemolytic Temporin-SHa Peptide Analogs Disrupt Cell Membrane of Methicillin-Resistant Staphylococcus aureus (MRSA)

Anti-microbial peptides (AMPs) have attracted major attention due to their potential bio-activities against some multidrug resistant pathogens. The present study evaluated the mechanism of actions of highly potent AMP temporin-SHa analogs, i.e., [G4a]-SHa, [G7a]-SHa, and [G10a]-SHa, against methicillin-resistant Staphylococcus aureus (MRSA) NCTC (13277) with minimum inhibitory concentrations (MICs) of 14.35, 7.16, and 3.58 µM, respectively. These analogs exhibited significant anti-MRSA activity at physiological salt concentration, 30% fetal bovine serum, and 30% human serum. [G4a]-SHa and [G7a]-SHa were non-hemolytic and non-cytotoxic to normal mouse fibroblast 3T3 cell and human Caco-2 cell line. Atomic force microscopy revealed that these analogs have profound effect on the morphological changes in MRSA surface with significant leakage of cell cytoplasmic content. Propidium iodide uptake kinetic assay and (bis-(1,3-dibutylbarbituric acid) trimethine oxonol) DiBAC₄(3) membrane depolarization assay demonstrated that these analogs display a membrane disrupting property, characterized by elevation of plasma membrane permeability and rapid transmembrane potential depolarization. [G10a]-SHa showed a significant anti-biofilm activity against biofilm forming S. aureus (ATCC 6538). Acute in vivo toxicity studies revealed that [G10a]-SHa possesses some toxic effect at 100-mg/kg dose. While [G4a]-SHa at 100 mg/kg, i.p. has no toxic effect even after 48 h, [G7a]-SHa also did not show any toxic effect at the dose of 100 mg/kg, i.p. during 24-h observation of animals. In conclusion, [G4a]-SHa, [G7a]-SHa, and [G10a]-SHa show improved activity against MRSA and stability compared to SHa peptide. Although highly potent, [G10a]-SHa, due to its hemolytic activity, might be more suitable for topical application, whereas [G4a]-SHa and [G7a]-SHa have potential to be used for systemic application.

Bioactive cationic peptides as potential agents for breast cancer treatment

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

The effects of incorporation of the counterparts and mimics of L-lysine on the antimicrobial activity, hemolytic activity, cytotoxicity and tryptic stability of antimicrobial peptide polybia-MPII

Due to the limited effects of conventional antibiotics on the increasing emergence of drug-resistant bacteria and fungi, novel antimicrobial agents were urgently needed to alleviate this phenomenon. Nowadays, antimicrobial peptides are believed to be a promising candidate for a new generation of antimicrobial drugs. Antimicrobial peptide polybia-MPII (MPII) was first isolated from the venom of the social wasp Polybia paulista with a broad spectrum of antimicrobial activity. In the present study, the counterparts and mimics of cationic amino acids of Lys, such as Arg, His, Orn, Dab and Dap were employed to substitute Lys in the sequence of MPII. The effects of the incorporation of these amino acids on its antimicrobial activity, hemolytic activity, cytotoxicity, enzyme stability and therapeutic potential were explored. Our results showed that although the incorporation of Arg could improve its antimicrobial activity, there is no improvement in enzyme stability. The incorporation of His makes MPII exert its antimicrobial activity in a pH-dependent manner. Notably, incorporating Dap could effectively decrease its hemolytic activity and cytotoxicity and enhance its enzyme stability against trypsin. In conclusion, this study would provide an effective strategy to improve the bioavailability and metabolic stability of AMPs while decrease their hemolytic activity and cytotoxicity.

SSTP1, a Host Defense Peptide, Exploits the Immunomodulatory IL6 Pathway to Induce Apoptosis in Cancer Cells

While the immunomodulatory pathways initiated in immune cells contribute to therapeutic response, their activation in cancer cells play a role in cancer progression. Also, many of the aberrantly expressed immunomodulators on cancer cells are considered as therapeutic targets. Here, we introduce host defense peptide (HDP), a known immuomodulator, as a therapeutic agent to target them. The cationic host defense peptides (HDPs), an integral part of the innate immune system, possess membranolytic activity, which imparts antimicrobial and antitumor efficacy to it. They act as immunomodulators by activating the immune cells. Though their antimicrobial function has been recently reassigned to immunoregulation, their antitumor activity is still attributed to its membranolytic activity. This membrane pore formation ability, which is proportional to the concentration of the peptide, also leads to side effects like hemolysis, limiting their therapeutic application. So, despite the identification of a variety of anticancer HDPs, their clinical utility is limited. Though HDPs are shown to exert the immunomodulatory activity through specific membrane targets on immune cells, their targets on cancer cells are unknown. We show that SSTP1, a novel HDP identified by shotgun cloning, binds to the active IL6/IL6Rα/gp130 complex on cancer cells, rearranging the active site residues. In contrast to the IL6 blockers inhibiting JAK/STAT activity, SSTP1 shifts the proliferative IL6/JAK/STAT signaling to the apoptotic IL6/JNK/AP1 pathway. In IL6Rα-overexpressing cancer cells, SSTP1 induces apoptosis at low concentration through JNK pathway, without causing significant membrane disruption. We highlight the importance of immunomodulatory pathways in cancer apoptosis, apart from its established role in immune cell regulation and cancer cell proliferation. Our study suggests that identification of the membrane targets for the promising anticancer HDPs might lead to the identification of new drugs for targeted therapy.

Peptide conjugates of 18β-glycyrrhetinic acid as potent inhibitors of α-glucosidase and AGEs-induced oxidation

18β-Glycyrrhetinic acid (18β-GA) is known for several biological activities, and has been the focus of extensive research for the development of therapeutic agents. In the current study, 18β-GA-peptide conjugates 2-11 were evaluated for their in vitro α-glucosidase inhibitory and antiglycation activities. Structure-activity relationship (SAR) established and molecular interactions of active bioconjugates with the enzyme's binding sites were predicted through molecular modeling approach. In tripeptide moiety of conjugates 2-11, peptide residue at position 1 was found to have a significant role on α-glucosidase inhibition. The most active 18β-GA-peptide conjugates 5 (18β-GA-Cys¹-Tyr²-Gly³), and 8 (18β-GA-Pro¹-Tyr²-Gly³) exhibited several-fold potent α-glucosidase inhibition (IC₅₀ values 20-28 μM), as compared to standard drug acarbose (IC₅₀ = 875.8 ± 2.10 µM). Kinetic studies of potent compounds, 4-8 revealed that conjugate 5 exhibits competitive-type of inhibition, while conjugates 6-8 showed a non-competitive type of inhibition. The simulation studies also supported the kinetic results that conjugate 5 (18β-GA-Cys¹-Tyr²-Gly³) inhibits the α-glucosidase enzyme by blocking its substrate binding site. AGEs-induced NO^• inhibitors play an important role in controlling the inflammation associated with diabetes mellitus. The peptide conjugates 2-11 were also evaluated in vitro for AGEs-induced NO^• inhibition using RAW 264.7 macrophage cell line. Our data revealed that conjugates 7-10 were the more potent AGEs-induced NO^• inhibitors, comparable to standards rutin, and PDTC. The peptide conjugate 5 (a competitive inhibitor of α-glucosidase) also exhibited a strong inhibitory activity against AGEs-induced NO^• production. Furthermore, peptide conjugates 2-11 were found non-cytotoxic to mouse fibroblast NIH-3T3, and murine macrophages RAW 264.7 cell lines. In conclusion, our data demonstrates that besides possessing strong α-glucosidase inhibition, the newly synthesized peptide conjugates also alleviated the AGEs-induced NO^• production in RAW macrophages. Dual inhibition of α-glucosidase enzyme, and AGEs-induced NO^• production by 18β-GA-peptide conjugates qualify them for further research in anti-diabetic drug discovery.

Antimicrobial peptides as potential therapeutics for breast cancer

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

Ethnopharmacological study of natural products used for traditional cancer therapy in Algeria

Traditional and complementary medicine constitutes an important, and often underestimated, source of healthcare for multiple diseases including cancer. However, little is known about the ethnomedical knowledge and practices in Northern Africa. The main objective of this study is to identify and analyze the variety of natural products used in Algerian ethnopharmacology for cancer therapy. For this purpose, semi-structured interviews with 225 traditional healers, herbalists and practitioners were realized in twelve locations in Algeria throughout field studies performed from June 2015 to July 2019. Interviews covered popular and vernacular names of the natural product, mode of use and administration, dose, period of treatment, toxicity and side effects among other data. The obtained results reveal the use of 113 medicinal plants (belonging to 53 families and 104 genera), 10 animal species and various products and by-products from different origins such as honey, olive oil, thorns, urine, milk, animal fat and the alkaline water of Zamzam. Basing on the frequency of citation (FC), use reports (UR) and use value (UV), the most used natural products for cancer treatment are honey (FC = 181, UR = 194, UV = 0.65), Nigella sativa L. (FC = 131, UR = 152, UV = 0.54), Aristolochia longa L. (FC = 118, UR = 144, UV = 0.51), Berberis vulgaris L. (FC = 111, UR = 142, UV = 0.51), Curcuma longa L. (FC = 107, UR = 121, UV = 0.43), Trigonella foenum-graecum L. (FC = 102; UR = 119, UV = 0.43), Citrus limon (L.) Obseck (FC = 97, UR = 120, UV = 0.43), Artemisia herba-alba Asso (FC = 92, UR = 115, UV = 0.41) and the holy water 'Zamzam' (FC = 110, UR = 110, UV = 0.43) respectively. Mixtures of two or more ingredients were frequently used. The use of Pelophylax saharicus skin' was reported for the first time for the treatment of visible tumors and skin cancer. This is the first study documenting the traditional uses of various natural products for cancer treatment in Algeria. Our findings are relevant to document the traditional uses of numerous natural products and to provide background basis to search for novel compounds for cancer therapy.

Temporin-SHa and Its Analogs as Potential Candidates for the Treatment of Helicobacter pylori

Helicobacter pylori is one of the most prevalent pathogens colonizing 50% of the world's population and causing gastritis and gastric cancer. Even with triple and quadruple antibiotic therapies, H. pylori shows increased prevalence of resistance to conventional antibiotics and treatment failure. Due to their pore-forming activity, antimicrobial peptides (AMP) are considered as a good alternative to conventional antibiotics, particularly in the case of resistant bacteria. In this study, temporin-SHa (a frog AMP) and its analogs obtained by Gly to Ala substitutions were tested against H. pylori. Results showed differences in the antibacterial activity and toxicity of the peptides in relation to the number and position of D-Ala substitution. Temporin-SHa and its analog NST1 were identified as the best molecules, both peptides being active on clinical resistant strains, killing 90-100% of bacteria in less than 1 h and showing low to no toxicity against human gastric cells and tissue. Importantly, the presence of gastric mucins did not prevent the antibacterial effect of temporin-SHa and NST1, NST1 being in addition resistant to pepsin. Taken together, our results demonstrated that temporin-SHa and its analog NST1 could be considered as potential candidates to treat H. pylori, particularly in the case of resistant strains.