Engineering BinB Pore-Forming Toxin for Selective Killing of Breast Cancer Cells.

Breast cancer is one of the most common cancers in women worldwide. Conventional cancer chemotherapy always has adverse side effects on the patient's healthy tissues. Consequently, combining pore-forming toxins with cell-targeting peptides (CTPs) is a promising anticancer strategy for selectively destroying cancer cells. Here, we aim to improve the target specificity of the BinB toxin produced from Lysinibacillus sphaericus (Ls) by fusing a luteinizing hormone-releasing hormone (LHRH) peptide to its pore-forming domain (BinBC) to target MCF-7 breast cancer cells as opposed to human fibroblast cells (Hs68). The results showed that LHRH-BinBC inhibited MCF-7 cell proliferation in a dose-dependent manner while leaving Hs68 cells unaffected. BinBC, at any concentration tested, did not affect the proliferation of MCF-7 or Hs68 cells. In addition, the LHRH-BinBC toxin caused the efflux of the cytoplasmic enzyme lactate dehydrogenase (LDH), demonstrating the efficacy of the LHRH peptide in directing the BinBC toxin to damage the plasma membranes of MCF-7 cancer cells. LHRH-BinBC also caused MCF-7 cell apoptosis by activating caspase-8. In addition, LHRH-BinBC was predominantly observed on the cell surface of MCF-7 and Hs68 cells, without colocalization with mitochondria. Overall, our findings suggest that LHRH-BinBC could be investigated further as a potential cancer therapeutic agent.

Natural and Designed Toxins for Precise Therapy: Modern Approaches in Experimental Oncology.

Cancer cells frequently overexpress specific surface receptors providing tumor growth and survival which can be used for precise therapy. Targeting cancer cell receptors with protein toxins is an attractive approach widely used in contemporary experimental oncology and preclinical studies. Methods of targeted delivery of toxins to cancer cells, different drug carriers based on nanosized materials (liposomes, nanoparticles, polymers), the most promising designed light-activated toxins, as well as mechanisms of the cytotoxic action of the main natural toxins used in modern experimental oncology, are discussed in this review. The prospects of the combined therapy of tumors based on multimodal nanostructures are also discussed.

Toxic Animal-Based Medicinal Materials Can Be Effective in Treating Endometriosis: A Scoping Review.

Animal toxins and venoms have recently been developed as cancer treatments possessing tumor cell growth-inhibitory, antiangiogenesis, and proapoptotic effects. Endometriosis is a common benign gynecological disorder in reproductive-age women, and no definite treatment for this disorder is without severe side effects. As endometriosis and malignant tumors share similar characteristics (progressive, invasive, estrogen-dependent growth, and recurrence), animal toxins and venoms are thought to be effective against endometriosis. The objective of this study was to outline studies using toxic animal-based medicinal materials (TMM) as endometriosis treatment and to explore its clinical applicability. Preclinical and clinical studies using TMM were searched for in four databases from inception to October 2020. A total of 20 studies of TMM on endometriosis were included. In eight clinical studies, herbal medicines containing TMM were effective in relieving symptoms of endometriosis, with no side effects. In twelve experimental studies, the main therapeutic mechanisms of TMM against endometriosis were proapoptotic, antiangiogenesis, estrogen level-reducing, and possible anti-inflammatory effects. TMM are thus considered promising sources for the development of an effective treatment method for endometriosis. Further studies are needed to clarify the therapeutic mechanism of TMM against endometriosis and to provide sufficient grounds for clinical application.

Cleistanthin A induces apoptosis and suppresses motility of colorectal cancer cells.

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Here, we investigated the molecular mechanisms that underpin the anticancer effects of cleistanthin A (CA) in two CRC cell lines, HCT 116, and SW480. At 48 h, CA exhibited apoptotic cytotoxic effects in both CRC cell lines, concomitant with reduction of an anti-apoptotic protein, survivin. Mechanistically, CA treatment significantly reduced the expression levels of ß-catenin and active-ß-catenin in a dose-dependent manner in both CRC cell lines. Moreover, CA suppressed the Wnt/ß-catenin signaling pathway by decreasing ß-catenin-mediated transcriptional activity and expression of ß-catenin target genes, AXIN2, CCND1, and survivin. Furthermore, CA also inhibited transcriptional activity in cells overexpressing a constitutively active ß-catenin S33Y, indicating a GSK-3ß-independent mechanism underlying the observed CA effects on CRC cells. Although cytotoxic activity was not observed with CA treatment at 24 h, cell migration and invasion were significantly reduced. In addition, CA suppressed V-type ATPase activity and focal adhesion kinase (FAK) phosphorylation. Collectively, our study reveals that CA has time-dependent effects on CRC cell phenotypes. First, short-term CA treatment inhibited CRC cell migration and invasion partly through the suppression of V-type ATPase activity. This suppression resulted in reduced FAK activation. Second, longer-term CA treatment decreased cell viability which correlated with the suppression of Wnt/ß-catenin signaling induced transcriptional activity. Altogether, our data suggest that CA has the potential to develop as an effective and novel therapeutic drug for CRC patients.

Snake venom three-finger toxins and their potential in drug development targeting cardiovascular diseases.

Cardiovascular diseases such as coronary and peripheral artery diseases, venous thrombosis, stroke, hypertension, and heart failure are enormous burden to health and economy globally. Snake venoms have been the sources of discovery of successful therapeutics targeting cardiovascular diseases. For example, the first-in-class angiotensin-converting enzyme inhibitor captopril was designed largely based on bradykinin-potentiating peptides from Bothrops jararaca venom. In the recent years, sensitive and high throughput approaches drive discovery and cataloging of new snake venom toxins. As one of the largest class of snake venom toxin, there are now>700 sequences of three-finger toxins (3FTxs) available, many of which are yet to be studied. While the function of 3FTxs are normally associated with neurotoxicity, increasingly more 3FTxs have been characterized to have pharmacological effects on cardiovascular systems. Here we focus on this family of snake venom toxins and their potential in developing therapeutics against cardiovascular diseases.

Animal toxins - Nature's evolutionary-refined toolkit for basic research and drug discovery.

Venomous animals have evolved toxins that interfere with specific components of their victim's core physiological systems, thereby causing biological dysfunction that aids in prey capture, defense against predators, or other roles such as intraspecific competition. Many animal lineages evolved venom systems independently, highlighting the success of this strategy. Over the course of evolution, toxins with exceptional specificity and high potency for their intended molecular targets have prevailed, making venoms an invaluable and almost inexhaustible source of bioactive molecules, some of which have found use as pharmacological tools, human therapeutics, and bioinsecticides. Current biomedically-focused research on venoms is directed towards their use in delineating the physiological role of toxin molecular targets such as ion channels and receptors, studying or treating human diseases, targeting vectors of human diseases, and treating microbial and parasitic infections. We provide examples of each of these areas of venom research, highlighting the potential that venom molecules hold for basic research and drug development.

Mobilizing Toxins for Cancer Treatment: Historical Perspectives and Current Strategies.

The level of complexity in a disease like cancer presents a number of challenges for effective treatment development, which require significant innovation to overcome [...].

Animal Venom Peptides as a Treasure Trove for New Therapeutics Against Neurodegenerative Disorders.

BACKGROUND: Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and cerebral ischemic stroke, impose enormous socio-economic burdens on both patients and health-care systems. However, drugs targeting these diseases remain unsatisfactory, and hence there is an urgent need for the development of novel and potent drug candidates. METHODS: Animal toxins exhibit rich diversity in both proteins and peptides, which play vital roles in biomedical drug development. As a molecular tool, animal toxin peptides have not only helped clarify many critical physiological processes but also led to the discovery of novel drugs and clinical therapeutics. RESULTS: Recently, toxin peptides identified from venomous animals, e.g. exenatide, ziconotide, Hi1a, and PcTx1 from spider venom, have been shown to block specific ion channels, alleviate inflammation, decrease protein aggregates, regulate glutamate and neurotransmitter levels, and increase neuroprotective factors. CONCLUSION: Thus, components of venom hold considerable capacity as drug candidates for the alleviation or reduction of neurodegeneration. This review highlights studies evaluating different animal toxins, especially peptides, as promising therapeutic tools for the treatment of different neurodegenerative diseases and disorders.

Is Mistletoe Treatment Beneficial in Invasive Breast Cancer? A New Approach to an Unresolved Problem.

BACKGROUND/AIM: In this retrospective study, we compared breast cancer patients treated with and without mistletoe lectin I (ML-I) in addition to standard breast cancer treatment in order to determine a possible effect of this complementary treatment. PATIENTS AND METHODS: This study included 18,528 patients with invasive breast cancer. Data on additional ML-I treatments were reported for 164 patients. We developed a "similar case" method with a distance measure retrieved from the beta variable in Cox regression to compare these patients, after stage adjustment, with their non-ML-1 treated counterparts in order to answer three hypotheses concerning overall survival, recurrence free survival and life quality. RESULTS: Raw data analysis of an additional ML-I treatment yielded a worse outcome (p=0.02) for patients with ML treatment, possibly due to a bias inherent in the ML-I-treated patients. Using the "similar case" method (a case-based reasoning approach) we could not confirm this harm for patients using ML-I. Analysis of life quality data did not demonstrate reliable differences between patients treated with ML-I treatment and those without proven ML-I treatment. CONCLUSION: Based on a "similar case" model we did not observe any differences in the overall survival (OS), recurrence-free survival (RFS), and quality of life data between breast cancer patients with standard treatment and those who in addition to standard treatment received ML-I treatment.

Potential Uses of Isolated Toxin Peptides in Neuropathic Pain Relief: A Literature Review.

Neuropathic pain is a subset of chronic pain that is caused by neurons that are damaged or firing aberrantly in the peripheral or central nervous systems. The treatment guidelines for neuropathic pain include antidepressants, calcium channel α2 delta ligands, topical therapy, and opioids as a second-line option. Pharmacotherapy has not been effective in the treatment of neuropathic pain except in the treatment of trigeminal neuralgia with carbamazepine. The inability to properly treat neuropathic pain causes frustration in both the patients and their treating physicians. Venoms, which are classically believed to be causes of pain and death, have peptide components that have been implicated in pain relief. Although some venoms are efficacious and have shown benefits in patients, their side-effect profile precludes their more widespread use. This review identifies and explores the use of venoms in neuropathic pain relief. This treatment can open doors to potential therapeutic targets. We believe that further research into the mechanisms of action of these receptors as well as their functions in nature will provide alternative therapies as well as a window into how they affect neuropathic pain.

The use of alpha-fetoprotein for the treatment of autoimmune diseases and cancer.

Alpha-fetoprotein is a shuttle protein that delivers nutrients through receptor-mediated endocytosis to embryotic cells. In adults, alpha-fetoprotein can shuttle drugs into alpha-fetoprotein receptor-positive myeloid-derived suppressor, regenerating and also cancer cells. Drugs with high-binding affinity to alpha-fetoprotein can activate or deplete targeted cells. Myeloid-derived suppressor cells activation leads to immune suppression that can be used for treating autoimmune diseases. On the other hand, toxins delivered by alpha-fetoprotein can damage myeloid-derived suppressor cells and consequently unleash innate and adaptive immunity to destroy cancer cells. Innate immunity natural killers reduce cancer stem cells and metastases. The new alpha-fetoprotein drug noncovalent complexes for immunotherapy change the local immune balance and has potential in oncology, autoimmune and infectious diseases treatment, inflammation, transplantation, vaccination, etc.

Snake Venom: From Deadly Toxins to Life-saving Therapeutics.

Snakes are fascinating creatures and have been residents of this planet well before ancient humans dwelled the earth. Venomous snakes have been a figure of fear, and cause notable mortality throughout the world. The venom constitutes families of proteins and peptides with various isoforms that make it a cocktail of diverse molecules. These biomolecules are responsible for the disturbance in fundamental physiological systems of the envenomed victim, leading to morbidity which can lead to death if left untreated. Researchers have turned these life-threatening toxins into life-saving therapeutics via technological advancements. Since the development of captopril, the first drug that was derived from bradykininpotentiating peptide of Bothrops jararaca, to the disintegrins that have potent activity against certain types of cancers, snake venom components have shown great potential for the development of lead compounds for new drugs. There is a continuous development of new drugs from snake venom for coagulopathy and hemostasis to anti-cancer agents. In this review, we have focused on different snake venom proteins / peptides derived drugs that are in clinical use or in developmental stages till to date. Also, some commonly used snake venom derived diagnostic tools along with the recent updates in this exciting field are discussed.

In vitro and in vivo anticancer activity of posterior salivary gland toxin from the cuttlefish Sepia pharaonis, Ehrenberg (1831).

Posterior salivary gland (PSG) toxins are high molecular weight toxins secreted by cephalopods and gastropods which possess immense potentials in biomedical applications. In the present study, the biomedical potentials of the PSG toxin from the cuttlefish, S. pharaonis was determined in vitro and in vivo. The cytostatic potentials of the PSG toxin was determined by the lymphocyte migration inhibition assay. The PSG toxin (50 µg/ml) effectively inhibited the migration of lymphocytes across the agarose gel matrix under the presence of lipopolysaccharide mitogen. The cytotoxicity of the PSG toxin against cancer cell lines was determined using the MTT assay. The PSG toxin exhibited highest cytotoxicity against the MCF-7 breast cancer cells (IC50-10.64 µM) followed by KB, HeLa and A549 cells. The PSG toxin also exhibited proportional release of LDH leakage by mitochondrial damage with an IC50-13.85 µM against MCF-7 breast cancer cells. Flow cytometry analysis revealed that the PSG toxin induced apoptosis in MCF-7 cells by cell cycle arrest at G0/G1 phase. The PSG toxin (80 mg/kg b.w.) exhibited pronounced reduction (29%) in tumor growth in experimentally induced breast carcinoma in female Balb/C mice, in vivo. Hematological analysis illustrated the restoration of blood and biochemical parameters by the PSG toxin in mice induced with tumor. Histopathology studies also revealed the restitution of morphological features in the mammary tumor and vital organs in mice treated with the PSG toxin without any observed toxicity and adverse effects. The PSG toxin further exhibited commendable potentials in the prevention of tumor metastasis into immediate organs viz lungs, thus functioning as an anti-metastatic agent. The results of the present study showed that the PSG toxin exhibited immense promise as a potential peptide based anticancer agent, in future.

Progress and challenges in the optimization of toxin peptides for development as pain therapeutics.

The number of new toxin peptide discoveries has been rapidly growing in the past few decades. Because of progress in proteomics, sequencing technologies, and high throughput bioassays, the search for new toxin peptides from venom collections and potency optimization has become manageable. However, to date, only six toxin peptide-derived therapeutics have been approved by the USFDA, with only one, ziconotide, for a pain indication. The challenge of venom-derived peptide therapeutic development remains in improving selectivity to the target and more importantly, in delivery of these peptides to the sites of action in the central and peripheral nervous system. In this review, we highlight peptide toxins that target major therapeutic targets for pain and discuss the challenges of developing toxin peptides as potential therapeutics.

Homeopathic mistletoe adverse reaction mimics nodal involvement in 18F-FDG PET/CT performed for evaluation of response to chemotherapy in lymphoma.

Some patients use complementary medicine. We present a patient with Hodgkin's lymphoma, scanned with 18F-FDG PET/CT for evaluation of response after chemotherapy, who was self-administering mistletoe as a homeopathic medicine product. The careful review of the images of the entire scan and patient collaboration in anamnesis were crucial to avoid a false positive result. A review of the published scientific data on the effects of mistletoe is also presented.

Stigmurin and TsAP-2 from Tityus stigmurus scorpion venom: Assessment of structure and therapeutic potential in experimental sepsis.

Microbial resistance to conventional antibiotics is a public health problem worldwide, motivating the search for new therapeutic alternatives in varied natural sources. Cationic peptides without disulfide bridges from scorpions have been targeted in this context, mainly due to their multifunctional action and the limited ability of microorganisms to develop resistance against them. The present study was focused on Stigmurin and TsAP-2, cationic peptides found in the transcriptome of the venom gland from the scorpion Tityus stigmurus. The aims were: to assess the secondary structure of TsAP-2 and the structural stability of both peptides by circular dichroism; to evaluate their antiproliferative effect, and antimicrobial activities in vitro, ex vivo and in vivo; and to investigate their therapeutic potential in a murine model of polymicrobial sepsis. Stigmurin and TsAP-2 secondary structures responded similarly to environment polarity changes, and were stable to temperature and pH variation. Both peptides showed antiproliferative effect on tumor cells. TsAP-2 showed lower cytotoxicity to normal cells, and had a mitogenic activity on murine macrophages. Stigmurin demonstrated bactericidal and bacteriostatic activity, depending on the microorganism, whereas TsAP-2 had bactericidal action upon different bacterial strains analyzed. Both peptides were able to reduce leukocyte migration, TNF-α levels and microorganism load in the peritoneal cavity after induction of experimental sepsis, decreasing inflammation in the lung and cecum of septic animals. TsAP-2 also reduced the release of nitric oxide in the peritoneal cavity. Taken together, these data suggest that Stigmurin and TsAP-2 are structurally stable molecules and are efficient in the control of the infectious focus in polymicrobial sepsis, with potential use as a prototype for the rational design of novel therapeutic agents.

Toxins and derivatives in molecular pharmaceutics: Drug delivery and targeted therapy.

Protein and peptide toxins offer an invaluable source for the development of actively targeted drug delivery systems. They avidly bind to a variety of cognate receptors, some of which are expressed or even up-regulated in diseased tissues and biological barriers. Protein and peptide toxins or their derivatives can act as ligands to facilitate tissue- or organ-specific accumulation of therapeutics. Some toxins have evolved from a relatively small number of structural frameworks that are particularly suitable for addressing the crucial issues of potency and stability, making them an instrumental source of leads and templates for targeted therapy. The focus of this review is on protein and peptide toxins for the development of targeted drug delivery systems and molecular therapies. We summarize disease- and biological barrier-related toxin receptors, as well as targeted drug delivery strategies inspired by those receptors. The design of new therapeutics based on protein and peptide toxins is also discussed.

Snake venom derived molecules in tumor angiogenesis and its application in cancer therapy; an overview.

Snake venom is a complex mixture of biologically and pharmacologically active components, comprising hydrolytic enzymes, non-enzymatic proteins/peptides, and small amounts of organic and inorganic molecules. The venom components are known to vary with geographic location, season, species and age of the snakes. The role of the venom in the snake is not primarily for self-defense, but in prey immobilization and its subsequent digestion. Hence, several digestive enzymes in venoms, in addition to their hydrolytic activity have evolved to interfere in diverse physiological processes that help in the immobilization of prey/victim. As snake components are capable of modulating the physiological response of envenomated prey/victim, they show promise as potential pharmacological tools, as drug leads and in diagnostic applications. This, in a practical sense to be a reality has to be linked to the advances in toxinology that provide investigators with an understanding of the pharmacodynamics of toxins together with improved understanding of the etiology of many human diseases and identification of potential sites for therapeutic intervention. This review aims at providing an overview on snake venom toxins and their derivatives that have potential anti-angiogenic effects for cancer treatment. Some of the anti-angiogenic components of snake venom like Snake venom metalloproteinases (SVMPs), Disintegrins, Phospholipases A2 (PLA2), CType Lectins (CLP), Vascular Apoptosis inducing Proteins (VAP) and L-Amino Acid Oxidases (LAAO) are discussed. This review aims at giving an overall view of these molecules and their mechanism of action as an effective antiangiogenic agent towards the treatment of cancer.

Biotoxins for cancer therapy.

In recent times, a number of studies have provided evidence that biotoxins present great potential as antitumor agents, such as snake venom, bee venom, some bacteria toxins and plant toxins, and thus could be used as chemotherapeutic agents against tumors. The biodiversity of venoms and toxins make them a unique source from which novel anticancer agent may be developed. Biotoxins, also known as natural toxins, include toxic substances produced by plants, animals and microorganisms. Here, we systematically list representative biological toxins that have antitumor properties, involving animal toxins, plant toxins, mycotoxins as well as bacterial toxins. In this review, we summarize the current knowledge involving biotoxins and the active compounds that have anti-cancer activity to induce cytotoxic, antitumor, immunomodulatory, and apoptotic effects in different tumor cells in vivo or in vitro. We also show insights into the molecular and functional evolution of biotoxins.