Preparation and In Vitro Evaluation of 131I-BmK CT as a Glioma-Targeted Agent

Recent developments in animal venom peptide nanotherapeutics with improved selectivity for cancer cells

Animal venoms are a rich source of bioactive peptides that efficiently modulate key receptors and ion channels involved in cellular excitability to rapidly neutralize their prey or predators. As such, they have been a wellspring of highly useful pharmacological tools for decades. Besides targeting ion channels, some venom peptides exhibit strong cytotoxic activity and preferentially affect cancer over healthy cells. This is unlikely to be driven by an evolutionary impetus, and differences in tumor cells and the tumor microenvironment are probably behind the serendipitous selectivity shown by some venom peptides. However, strategies such as bioconjugation and nanotechnologies are showing potential to improve their selectivity and potency, thereby paving the way to efficiently harness new anticancer mechanisms offered by venom peptides. This review aims to highlight advances in nano- and chemotherapeutic tools and prospective anti-cancer drug leads derived from animal venom peptides.

Scorpion venoms and associated toxins as anticancer agents: update on their application and mechanism of action

Cancer remains one of the deadliest non-infectious diseases of the 21^st century, causing millions of mortalities per year worldwide. Analyses of conventional treatments, such as radiotherapy and chemotherapy, have shown not only a lower therapeutic efficiency rate but also plethora of side-effects. Considering the desperate need to identify promising anticancer agents, researchers are in quest to design and develop new tumoricidal drugs from natural sources. Over the past few years, scorpion venoms have shown exemplary roles as pivotal anticancer agents. Scorpion venoms associated metabolites, particularly toxins demonstrated in vitro anticancer attributes against diversified cell lines by inhibiting the growth and progression of the cell cycle, inhibiting metastasis by blocking ion channels such as K⁺ and Cl^- , and/or inducing apoptosis by intrinsic and extrinsic pathways. This review sheds light not only on in vitro anticancer properties of distinct scorpion venoms and their toxins, but also on their mechanism of action for designing and developing new therapeutic drugs in future.

Peptides with therapeutic potential in the venom of the scorpion Buthus martensii Karsch

The scorpion Buthus martensii Karsch (BmK) has generated significant interest due to the presence of biologically active peptides in its venom. In the past decade, dozens of different peptides from BmK have been identified. Most of the peptides are neurotoxins and are responsible for the toxicity of BmK venom. Other peptides, including neurotoxins and non-disulfide-bridged peptides, show potential anticancer, antimicrobial, analgesic, and anti-epileptic therapeutic effects. These peptides are attractive candidates for drug development, and peptide derivatives have also been designed to enhance their therapeutic potential, such as ADWX-1 and Kn2-7. In this review, we provide an overview of the most promising peptides found in BmK venom and of modified peptide derivatives showing therapeutic potential.

Anti-metastatic effect of 131I-labeled Buthus martensii Karsch chlorotoxin in gliomas

The present study investigated the underlying molecular mechanism by which Buthus martensii Karsch chlorotoxin (BmK CT) inhibits the invasion and metastasis of glioma cells and the possibility of 131I‑labeled BmK CT (131I‑BmK CT) as a novel targeted agent for the treatment of glioma. The impact of BmK CT with and without 131I radiolabeling on the invasion and metastasis of glioma cells in vitro was studied. Cell viability was assessed using Cell Counting Kit‑8 and plate colony formation assays in order to confirm the cytotoxicity of BmK CT and 131I‑BmK CT at different concentrations. Transwell invasion and wound‑healing assays were conducted in order to investigate the inhibitory effects BmK CT and 131I‑BmK CT on cell migration and invasion. Furthermore, western blotting, ELISA immunofluorescence and a gelatin zymography assay were performed to evaluate changes in the protein expression levels of glioma cells following treatment with BmK CT or 131I‑BmK CT. The results indicated that BmK CT inhibits the invasion and metastasis of glioma cells via regulation of tissue inhibitor of metalloproteinase‑2 expression and that 131I‑BmK CT has the potential to be a novel targeted therapeutic drug for glioma.

SPECT imaging and radionuclide therapy of glioma using 131I labeled Buthus martensii Karsch chlorotoxin

Gliomas, the most prevalent type of brain tumor in adults, are associated with high rates of morbidity and mortality. Recent studies on ¹³¹I labeled scorpion toxins suggest they can be developed as tumor-specific agents for glioma diagnosis and treatment. This study investigated the potential of ¹³¹I labeled Buthus martensii Karsch chlorotoxin (¹³¹I-BmK CT) as a new approach for targeted imaging and therapy of glioma. The results showed that ¹³¹I can be successfully linked to BmK CT with satisfactory radiochemical purity and stability and that ¹³¹I-BmK CT markedly inhibited glioma cell growth in a dose and time dependent manner, with significant accumulation in glioma cells in vitro. Persistent intratumoral radioiodine retention and specific accumulation of ¹³¹I-BmK CT were observed in C6 glioma tumor, which was clearly visualized by SPECT imaging. Both intratumoral and intravenous injections of ¹³¹I-BmK CT could result in significant tumor inhibition efficacy and prolonging the lifetime of tumor-bearing mice. Based on these promising results, it is concluded that ¹³¹I-BmK CT has the potential to be explored as a novel tool for SPECT imaging and radionuclide therapy of glioma.

131I-labeled multifunctional dendrimers modified with BmK CT for targeted SPECT imaging and radiotherapy of gliomas

Aim: The poly(amidoamine) dendrimers modified with Buthus martensii Karsch chlorotoxin (BmK CT) were developed as a 131I delivery system for glioma-targeted imaging and therapy. Materials & methods: Dendrimers before and after labeling 131I were synthetized and their physicochemical properties were tested. The targeting and therapeutic efficacy of 131I-G5.NHAc-HPAO-(PEG-BmK CT)-(mPEG) dendrimer against glioma was evaluated in vitro and in vivo. Results: All the dendrimers were stable under different conditions. BmK CT modification increased the cellular uptake of dendrimers in C6 glioma cells, but not in the normal RLE-6TN cells. 131I-G5.NHAc-HPAO-(PEG-BmK CT)-(mPEG) dendrimer was radiochemically pure and could be applied in glioma-targeting single-photon emission CT (SPECT) imaging and radiotherapy. Conclusion: 131I-G5.NHAc-HPAO-(PEG-BmK CT)-(mPEG) complex is a promising multifunctional nanoplatform for glioma-specific nuclear imaging and radiotherapy.

Scorpion venom components as potential candidates for drug development

Scorpions are well known for their dangerous stings that can result in severe consequences for human beings, including death. Neurotoxins present in their venoms are responsible for their toxicity. Due to their medical relevance, toxins have been the driving force in the scorpion natural compounds research field. On the other hand, for thousands of years, scorpions and their venoms have been applied in traditional medicine, mainly in Asia and Africa. With the remarkable growth in the number of characterized scorpion venom components, several drug candidates have been found with the potential to tackle many of the emerging global medical threats. Scorpions have become a valuable source of biologically active molecules, from novel antibiotics to potential anticancer therapeutics. Other venom components have drawn attention as useful scaffolds for the development of drugs. This review summarizes the most promising candidates for drug development that have been isolated from scorpion venoms.