Protein and Peptide Letters - Volume 31, Issue 4, 2024

The landscape of cancer therapy has witnessed a paradigm shift with the emergence of innovative delivery systems, and Guanidinium-based Peptide Dendrimers have emerged as a vanguard in this transformative journey. With their unique molecular architecture and intrinsic biocompatibility, these dendrimers offer a promising avenue for the targeted delivery of therapeutic cargo in cancer treatment. This comprehensive review delves into the intricate world of Guanidinium- based Peptide Dendrimers, unraveling their structural intricacies, mechanisms of action, and advancements that have propelled them from laboratory curiosities to potential clinical champions. Exploiting the potent properties of guanidinium, these dendrimers exhibit unparalleled precision in encapsulating and transporting diverse cargo molecules, ranging from conventional chemotherapeutics to cutting-edge nucleic acids. The review navigates the depths of their design principles, investigating their prowess in traversing the complex terrain of cellular barriers for optimal cargo delivery. Moreover, it delves into emerging trends, such as personalized therapeutic approaches, multimodal imaging, and bioinformatics-driven design, highlighting their potential to redefine the future of cancer therapy. Crucially, the review addresses the pivotal concerns of biocompatibility and safety, examining cytotoxicity profiles, immune responses, and in vivo studies. It underscores the importance of aligning scientific marvels with the stringent demands of clinical applications. Through each section, the narrative underscores the promises and possibilities that Guanidinium-based Peptide Dendrimers hold and how they can potentially reshape the landscape of precision cancer therapy.

Background: Diosmetin is an O-methylated flavone and the aglycone part of the flavonoid glycosides diosmin that occurs naturally in citrus fruits. Pharmacologically, diosmetin is reported to exhibit anticancer, antimicrobial, antioxidant, oestrogenic, and anti-inflammatory activities. Objective: This comprehensive review was aimed to critically explore diverse pharmacological activities exhibited by diosmetin. Along with that, this review can also identify potential research areas with an elucidation of the multifactorial underlying signaling mechanism of action of diosmetin in different diseases. Methods: A comprehensive collection of evidence and insights was obtained from scientific journals and books from physical libraries and electronic platforms like Google Scholar and PubMed. The time frame selected was from year 1992 to July 2023. Results: The review delves into diosmetin's impact on cellular signaling pathways and its potential in various diseases. Due to its ability to modulate signaling pathways and reduce oxidative stress, it can be suggested as a potential versatile therapeutic agent for mitigating oxidative stressassociated pathogenesis. Conclusion: The amalgamation of the review underscores diosmetin's promising role as a multifaceted therapeutic agent, highlighting its potential for drug development and clinical applications.

Metabolic dysfunction-associated Fatty Liver Disease (MAFLD) is a chronic liver disease characterized by the accumulation of fat in the liver and hepatic steatosis, which can progress to critical conditions, including Metabolic dysfunction-associated Steatohepatitis (MASH), liver fibrosis, hepatic cirrhosis, and hepatocellular carcinoma. Galectin-3, a member of the galectin family of proteins, has been involved in cascades that are responsible for the pathogenesis and progression of liver fibrosis in MAFLD. This review summarizes the present understanding of the role of galectin-3 in the severity of MAFLD and its associated liver fibrosis. The article assesses the underlying role of galectin-3-mediated fibrogenesis, including the triggering of hepatic stellate cells, the regulation of extracellular degradation, and the modulation of immune reactions and responses. It also highlights the assessments of the potential diagnostic and therapeutic implications of galectin-3 in liver fibrosis during MAFLD. Overall, this review provides insights into the multifaceted interaction between galectin-3 and liver fibrosis in MAFLD, which could lead to the development of novel strategies for diagnosis and treatment of this prevalent liver disease.

Background: Protease 3C (3Cpro) is the only protease encoded in the human hepatitis A virus genome and is considered as a potential target for antiviral drugs due to its critical role in the viral life cycle. Additionally, 3Cpro has been identified as a potent inducer of ferroptosis, a newly described type of cell death. Therefore, studying the molecular mechanism of 3Cpro functioning can provide new insights into viral-host interaction and the biological role of ferroptosis. However, such studies require a reliable technique for producing the functionally active recombinant enzyme. Objective: Here, we expressed different modified forms of 3Cpro with a hexahistidine tag on the N- or C-terminus to investigate the applicability of immobilized metal Ion affinity chromatography (IMAC) for producing 3Cpro. Methods: We expressed the proteins in Escherichia coli and purified them using IMAC, followed by gel permeation chromatography. The enzymatic activity of the produced proteins was assayed using a specific chromogenic substrate. Results: Our findings showed that the introduction and position of the hexahistidine tag did not affect the activity of the enzyme. However, the yield of the target protein was highest for the variant with seven C-terminal residues replaced by a hexahistidine sequence. Conclusion: We demonstrated the applicability of our approach for producing recombinant, enzymatically active 3Cpro.

Background: The most fatal form of Visceral leishmaniasis or kala-azar is caused by the intracellular protozoan parasite Leishmania donovani. The life cycle and the infection pathway of the parasite are regulated by the small GTPase family of Rab proteins. The involvement of Rab proteins in neurodegenerative amyloidosis is implicated in protein misfolding, secretion abnormalities and dysregulation. The inter and intra-cellular shuttlings of Rab proteins are proposed to be aggregation-prone. However, the biophysical unfolding and aggregation of protozoan Rab proteins is limited. Understanding the aggregation mechanisms of Rab protein will determine their physical impact on the disease pathogenesis and individual health. Objective: This work investigates the acidic pH-induced unfolding and aggregation of a recombinant Rab2 protein from L. donovani (rLdRab2) using multi-spectroscopic probes. Methods: The acidic unfolding of rLdRab2 is characterised by intrinsic fluorescence and ANS assay, while aggregation is determined by Thioflavin-T and 90129;° light scattering assay. Circular dichroism determined the secondary structure of monomers and aggregates. The aggregate morphology was imaged by transmission electron microscopy. Results: rLdRab2 was modelled to be a Rab2 isoform with loose globular packing. The acidinduced unfolding of the protein is a plausible non-two-state process. At pH 2.0, a partially folded intermediate (PFI) state characterised by ~ 30% structural loss and exposed hydrophobic core was found to accumulate. The PFI state slowly converted into well-developed protofibrils at high protein concentrations demonstrating its amyloidogenic nature. The native state of the protein was also observed to be aggregation-prone at high protein concentrations. However, it formed amorphous aggregation instead of fibrils. Conclusion: To our knowledge, this is the first study to report in vitro amyloid-like behaviour of Rab proteins in L donovani. This study provides a novel opportunity to understand the complete biophysical characteristics of Rab2 protein of the lower eukaryote, L. donovani.

Background: Radiotherapy is the primary treatment choice for Nasopharyngeal Carcinoma (NPC). However, its efficacy is compromised due to radioresistance. Ferroptosis, a novel iron-dependent regulated cell death induced by Ionizing Radiation (IR), plays a role in promoting cancer cell death. Yet, the relationship between enhanced ferroptosis and increased sensitivity of NPC cells to IR remains poorly understood. Objective: This study aimed to explore the association between IR and ferroptosis in NPC, as well as the role of the ferroptosis repressor SLC7A11 in IR-treated NPC cells. Methods: CNE1 and HNE-2 NPC cells were subjected to IR treatment. We performed qPCR and western blotting to evaluate the expression of ferroptosis-related genes in both control and IR-treated NPC cells. Additionally, we used the MTT assay to measure the viability of these NPC cells. JC-1 and DCFH-DA staining were employed to assess mitochondrial membrane potential and Reactive Oxygen Species (ROS) levels in both control and IR-treated NPC cells. Furthermore, we examined the levels of Fe²⁺, Malondialdehyde (MDA), reduced Glutathione (GSH), and oxidized glutathione (GSSG) in these cells. Moreover, we depleted SLC7A11 in IR-treated NPC cells to investigate its impact on the ferroptosis of these cells. Results: IR upregulated the expression of ferroptosis-related genes, including SLC7A11, ACSL4, COX2, FTH1, and GPX4, in CNE1 and HNE-2 cells. IR treatment also resulted in decreased cell viability, disrupted mitochondrial membrane potential, increased ROS levels, altered glutathione levels, and elevated Fe²⁺ levels. Knockdown of SLC7A11 enhanced the sensitivity of NPC cells to IR. Conclusion: IR may induce ferroptosis in NPC cells, and stimulating ferroptosis could potentially serve as a therapeutic strategy to enhance the efficacy of IR in treating NPC patients.

Background: Cancer remains a global burden, with increasing mortality rates. Current cancer treatments involve controlling the transcription of malignant DNA genes, either directly or indirectly. DNA exhibits various structural forms, including the G-quadruplex (G4), a secondary structure in guanine-rich regions. G4 plays a crucial role in cellular processes by regulating gene expression and telomerase function. Researchers have recently identified G4-stabilizing binding agents as promising anti-cancer compounds. Additionally, peptides have emerged as effective anticancer pharmaceuticals due to their ability to form multiple hydrogen bonds, electrostatic interactions, and van der Waals forces. These properties enable peptides to bind to specific areas of DNA chains selectively. However, despite these advancements, designing G4-binding peptides remains challenging due to a lack of comprehensive information. Objective: In our present study, we employed an in silico fragment-based approach to design G4- binding peptides. This innovative method combines machine learning classification, molecular docking, and dynamics simulation. Methods: AutoDock Vina and Gromacs performed molecular docking and MD simulation, respectively. The machine learning algorithm was implemented by Scikit-learn. Peptide synthesis was performed using the SPPS method. The DNA binding affinity was measured by applying spectrophotometric titration. Results: As a result of this approach, we identified a high-scoring peptide (p10; sequence: YWRWR). The association constant (Ka) between p10 and the ctDNA double helix chain was 4.45 × 10⁵ M^-1. Molecular modeling studies revealed that p10 could form a stable complex with the G4 surface. Conclusion: The obtained Ka value of 4.45 × 10⁵ M^-1 indicates favorable interactions. Our findings highlight the role of machine learning and molecular modeling approaches in designing new G4-binding peptides. Further research in this field could lead to targeted treatments that exploit the unique properties of G4 structures.