Apoptosis-inducing activity of synthetic hydrocarbon-stapled peptides in H358 cancer cells expressing KRASG12C

Peptide inhibitors targeting Ras and Ras-associated protein-protein interactions

Peptides represent attractive molecules for targeting protein-protein interactions, and peptide drug development has made great progress during the last decades. Ras protein, the most promising target in cancer therapy, is one of the major growth drivers in various cancers. Although many small molecule inhibitors have been reported to effectively target Ras protein and some inhibitors (such as MRTX849 and AMG 510) have been translated into clinical application, just a few peptide inhibitors have been reported. Here we summarize different types of peptide inhibitors, including monocyclic peptides, bicyclic peptides, stapled peptides, and proteomimetic inhibitors, developed in recent years; emphasize the limits and achievements; and discuss the outlook and challenges associated with future research in peptide inhibitors. This review aims to provide a reference for the discovery of Ras peptide inhibitors.

Chemical Strategies towards the Development of Effective Anticancer Peptides

Cancer is increasingly recognized as one of the primary causes of death and has become a multifaceted global health issue. Modern medical science has made significant advancements in the diagnosis and therapy of cancer over the past decade. The detrimental side effects, lack of efficacy, and multidrug resistance of conventional cancer therapies have created an urgent need for novel anticancer therapeutics or treatments with low cytotoxicity and drug resistance. The pharmaceutical groups have recognized the crucial role that peptide therapeutic agents can play in addressing unsatisfied healthcare demands and how these become great supplements or even preferable alternatives to biological therapies and small molecules. Anticancer peptides, as a vibrant therapeutic strategy against various cancer cells, have demonstrated incredible anticancer potential due to high specificity and selectivity, low toxicity, and the ability to target the surface of traditional "undruggable" proteins. This review will provide the research progression of anticancer peptides, mainly focusing on the discovery and modifications along with the optimization and application of these peptides in clinical practice.

VT204: A Potential Small Molecule Inhibitor Targeting KRASG12C Mutation for Therapeutic Intervention in Non-Small Cell Lung Cancer

Objectives: The development of effective treatments for non-small cell lung cancer (NSCLC), particularly targeting the KRASG12C mutation, remains a challenge. In this study, we investigated the therapeutic potential of VT204, a small molecule inhibitor of KRASG12C, in NSCLC. Methods: To achieve the objectives, we conducted a comprehensive set of experimental methods. In vitro experiments involved the investigation of VT204 on proliferation, apoptosis, cell cycle dynamics, migration, invasion, and on the RAF/MEK/ERK signaling pathway in NCI-H358 cells. In addition, in vivo experiments were performed to evaluate the influence of VT204 on tumor growth. Results: We demonstrated that VT204 effectively suppressed cell proliferation in NCI-H358 cells, with significant inhibition observed at a concentration of 8 μM. Colony formation assays further supported the inhibitory effect of VT204 on NCI-H358 cell growth. Moreover, VT204 exhibited notable effects on suppressing migration and invasion capacities of NCI-H358 cells, indicating its potential as a metastasis-inhibiting agent. Mechanistic investigations revealed that VT204 induced apoptosis and G2M-phase cell cycle arrest in NCI-H358 cells. Additionally, VT204 modulated the RAF/MEK/ERK signaling pathway, leading to reduced phosphorylation of ERK. In vivo studies using xenograft models confirmed the inhibitory effect of VT204 on NCI-H358 tumor growth. Conclusion: These findings highlight VT204 as a promising therapeutic candidate for NSCLC targeting the KRASG12C mutation.

Unleashing the potential of natural biological peptide Macropin: Hydrocarbon stapling for effective breast cancer treatment

The identification of novel candidate molecules with the potential to revolutionize the treatment of breast cancer holds profound clinical significance. Macropin (Mac)-1, derived from the venom of wild bees, emerges as an auspicious therapeutic agent for combating breast cancers. Nevertheless, linear peptides have long grappled with the challenges of traversing cell membranes and succumbing to protease hydrolysis. To address this challenge, the present study employed hydrocarbon stapling modification to synthesize a range of stapled Mac-1 peptides, which were comprehensively evaluated for their chemical and biological properties. Significantly, Mac-1-sp4 exhibited a remarkable set of improvements, including enhanced helicity, proteolytic stability, cell membrane permeability, induction of cell apoptosis, in vivo antitumor activity, and inhibition of tubulin polymerization. This study explores the significant impact of the hydrocarbon stapling technique on the secondary structure, hydrolase stability, and biological activity of Mac-1, shedding light on its potential as a revolutionary and potent anti-breast cancer therapy. The findings establish a strong basis for the development of innovative and highly effective anti-tumor treatments.

Peptide Stapling Applied to Antimicrobial Peptides

Antimicrobial peptides (AMPs) are considered a promising therapeutic approach against multi-drug resistant microorganisms. Besides their advantages, there are limitations to be overcome so that these molecules can become market competitive. One of the biggest limitations is proteolytic susceptibility, which could be overcome by structural modifications such as cyclization, especially for helix-constraining strategies. Over the years, many helix stabilization techniques have arisen, such as lactam-bridging, triazole-based, N-alkylation and all-hydrocarbon stapling. All-hydrocarbon stapling takes advantage of modified amino acid residues and olefinic cross-linking to constrain peptide helices. Despite being a well-established strategy and presenting efficient stability results, there are different limitations especially related to toxicity. In this review, recent studies on stapled AMPs for antimicrobial usage are explored with the aim of understanding the future of these molecules as putative antimicrobial agents.

Short hydrocarbon stapled ApoC2-mimetic peptides activate lipoprotein lipase and lower plasma triglycerides in mice

Introduction

Defects in lipolysis can lead to hypertriglyceridemia, which can trigger acute pancreatitis and is also associated with cardiovascular disease. Decreasing plasma triglycerides (TGs) by activating lipoprotein lipase (LPL) with ApoC2 mimetic peptides is a new treatment strategy for hypertriglyceridemia. We recently described a dual ApoC2 mimetic/ApoC3 antagonist peptide called D6PV that effectively lowered TG in several mouse models but has limitations in terms of drug development. The aim of this study was to create the next generation of ApoC2 mimetic peptides.

Methods

We employed hydrocarbon staples, as well as select amino acid substitutions, to make short single helical mimetic peptides based on the last helix of ApoC2. Peptides were first tested for their ability to activate LPL and then in hypertriglyceridemia mouse models. All-atom simulations of peptides were performed in a lipid-trilayer model of TG-rich lipoproteins to discern their possible mechanism of action.

Results

We designed a single stapled peptide called SP1 (21 residues), and a double stapled (stitched) peptide called SP2 (21 residues) and its N-terminal acylated analogue, SP2a. The hydrocarbon staples increased the amphipathicity of the peptides and their ability to bind lipids without interfering with LPL activation. Indeed, from all-atom simulations, the conformations of SP1 and SP2a are restrained by the staples and maintains the proper orientation of the LPL activation motif, while still allowing their deeper insertion into the lipid-trilayer model. Intraperitoneal injection of stapled peptides (1-5 umoles/kg) into ApoC2-hypomorphic mice or human ApoC3-transgenic resulted in an 80%-90% reduction in plasma TG within 3 h, similar to the much longer D6PV peptide (41 residues). Other modifications (replacement L-Glu20, L-Glu21 with their D-isomers, N-methylation of Gly19, Met2NorLeu and Ala1alpha-methylAla substitutions, N-terminal octanoylation) were introduced into the SP2a peptide. These changes made SP2a highly resistant to proteolysis against trypsin, pepsin, and Proteinase K, while maintaining similar efficacy in lowering plasma TG in mice.

Conclusion

We describe a new generation of ApoC2 mimetic peptides based on hydron carbon stapling that are at least equally potent to earlier peptides but are much shorter and resistant to proteolysis and could be further developed into a new therapy for hypertriglyceridemia.

Methoxylated Cinnamic Esters with Antiproliferative and Antimetastatic Effects on Human Lung Adenocarcinoma Cells

Lung cancer is the leading cause of cancer mortality worldwide, and malignant melanomas are highly lethal owing to their elevated metastatic potential. Despite improvements in therapeutic approaches, cancer treatments are not completely effective. Thus, new drug candidates are continuously sought. We synthesized mono- and di-methoxylated cinnamic acid esters and investigated their antitumor potential. A cell viability assay was performed to identify promising substances against A549 (non-small-cell lung cancer) and SK-MEL-147 (melanoma) cells. (E)-2,5-dimethoxybenzyl 3-(4-methoxyphenyl)acrylate (4m), a monomethoxylated cinnamic acid derivative, was identified as the lead antitumor compound, and its antitumor potential was deeply investigated. Various approaches were employed to investigate the antiproliferative (clonogenic assay and cell cycle analysis), proapoptotic (annexin V assay), and antimigratory (wound-healing and adhesion assays) activities of 4m on A549 cells. In addition, western blotting was performed to explore its mechanism of action. We demonstrated that 4m inhibits the proliferation of A549 by promoting cyclin B downregulation and cell cycle arrest at G2/M. Antimigratory and proapoptotic activities of 4m on A549 were also observed. The antitumor potential of 4m involved its ability to modulate the mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway once phosphorylated-ERK expression was considerably reduced in response to treatment. Our findings demonstrate that 4m is a promising anticancer drug candidate.

Design of Orally-bioavailable Tetra-cyclic phthalazine SOS1 inhibitors with high selectivity against EGFR

KRAS mutations (G12C, G12D, etc.) are implicated in the oncogenesis and progression of many deadliest cancers. Son of sevenless homolog 1 (SOS1) is a crucial regulator of KRAS to modulate KRAS from inactive to active states. We previously discovered tetra-cyclic quinazolines as an improved scaffold for inhibiting SOS1-KRAS interaction. In this work, we report the design of tetra-cyclic phthalazine derivatives for selectively inhibiting SOS1 against EGFR. The lead compound 6c displayed remarkable activity to inhibit the proliferation of KRAS(G12C)-mutant pancreas cells. 6c showed a favorable pharmacokinetic profile in vivo, with a bioavailability of 65.8% and exhibited potent tumor suppression in pancreas tumor xenograft models. These intriguing results suggested that 6c has the potential to be developed as a drug candidate for KRAS-driven tumors.

Feedback activation of EGFR/wild-type RAS signaling axis limits KRASG12D inhibitor efficacy in KRASG12D-mutated colorectal cancer

Colorectal cancer (CRC), which shows a high degree of heterogeneity, is the third most deadly cancer worldwide. Mutational activation of KRAS^G12D occurs in approximately 10-12% of CRC cases, but the susceptibility of KRAS^G12D-mutated CRC to the recently discovered KRAS^G12D inhibitor MRTX1133 has not been fully defined. Here, we report that MRTX1133 treatment caused reversible growth arrest in KRAS^G12D-mutated CRC cells, accompanied by partial reactivation of RAS effector signaling. Through a drug-anchored synthetic lethality screen, we discovered that epidermal growth factor receptor (EGFR) inhibition was synthetic lethal with MRTX1133. Mechanistically, MRTX1133 treatment downregulated the expression of ERBB receptor feedback inhibitor 1 (ERRFI1), a crucial negative regulator of EGFR, thereby causing EGFR feedback activation. Notably, wild-type isoforms of RAS, including H-RAS and N-RAS, but not oncogenic K-RAS, mediated signaling downstream of activated EGFR, leading to RAS effector signaling rebound and reduced MRTX1133 efficacy. Blockade of activated EGFR with clinically used antibodies or kinase inhibitors suppressed the EGFR/wild-type RAS signaling axis, sensitized MRTX1133 monotherapy, and caused the regression of KRAS^G12D-mutant CRC organoids and cell line-derived xenografts. Overall, this study uncovers feedback activation of EGFR as a prominent molecular event that restricts KRAS^G12D inhibitor efficacy and establishes a potential combination therapy consisting of KRAS^G12D and EGFR inhibitors for patients with KRAS^G12D-mutated CRC.

High-Throughput Screening of Stapled Helical Peptides in Drug Discovery

Therapeutic peptides have revolutionized treatment for a number of human diseases. In particular, the past two decades have witnessed rapid progress of stapled helical peptides in drug discovery. Stapled helical peptides are chemically modified and constrained in their bioactive α-helical conformation. Compared to unstabilized linear peptides, stapled helical peptides exhibit superior binding affinity and selectivity, enhanced membrane permeability, and improved metabolic stability, presenting exciting promise for targeting otherwise challenging protein-protein interfaces. In this Perspective, we summarize recent applications of high-throughput screening technologies for identification of potent stapled helical peptides with optimized binding properties. We expect to provide a broad reference to accelerate the development of stapled helical peptides as the next generation of therapeutic peptides for various human diseases.

Multi-Omics Analysis Reveals that the Antimicrobial Kasugamycin Potential Targets Nitrate Reductase in Didymella segeticola to Achieve Control of Tea Leaf Spot

Because of the lack of effective disease management measures, tea leaf spot-caused by the fungal phytopathogen Didymella segeticola (syn. Phoma segeticola)-is an important foliar disease. The important and widely used agricultural antimicrobial kasugamycin (Ksg), produced by the Gram-positive bacterium Streptomyces kasugaensis, effects high levels of control against crop diseases. The results of this study indicated that Ksg could inhibit the growth of D. segeticola hyphae in vitro with a half-maximal effective concentration (EC₅₀) of 141.18 μg ml^-1. Meanwhile, the curative effect in vivo on the pathogen in detached tea leaves also demonstrated that Ksg induced some morphological changes in organelles, septa, and cell walls as observed by optical microscopy and by scanning and transmission electron microscopy. This may indicate that Ksg disturbs biosynthesis of key metabolites, inhibiting hyphal growth. Integrated transcriptomic, proteomic, and bioinformatic analyses revealed that differentially expressed genes or differentially expressed proteins in D. segeticola hyphae in response to Ksg exposure were involved with metabolic processes and biosynthesis of secondary metabolites. Molecular docking studies indicated that Ksg may target nitrate reductase (NR), and microscale thermophoresis assay showed greater affinity with NR, potentially disturbing nitrogen assimilation and subsequent metabolism. The results indicated that Ksg inhibits the pathogen of tea leaf spot, D. segeticola, possibly by binding to NR, disturbing fungal metabolism, and inducing subsequent changes in hyphal growth and development.