Stapled peptide PROTAC induced significantly greater anti-PD-L1 effects than inhibitor in human cervical cancer cells

The Peptide PROTAC Modality: A New Strategy for Drug Discovery

In recent years, proteolysis targeting chimera (PROTAC) technology has made significant progress in the field of drug development. Traditional drugs mainly focus on inhibiting or activating specific proteins, while PROTAC technology provides new ideas for treating various diseases by inducing the degradation of target proteins. Especially for peptide PROTACs, due to their unique structural and functional characteristics, they have become a hot research topic. This review provides a detailed description of the key components, mechanisms, and design principles of peptide PROTACs, elaborates on their applications in skin-related diseases, oncology, and other potential therapeutic fields, analyzes their advantages and challenges, and looks forward to their future development prospects. The development of peptide PROTAC technology not only opens up new paths for drug research and development, but also provides new ideas for solving the resistance and safety issues faced by traditional small-molecule drugs. Compared with small-molecule PROTACs, peptide PROTACs have advantages such as multitargeting, biodegradability, low toxicity, and flexibility in structural design. With the deepening of research and the continuous maturity of technology, peptide PROTACs are expected to become one of the important strategies for future drug discovery, providing new hope for the treatment of more intractable diseases. Peptide PROTACs are ushering in a new era of precision medicine.

Stapled peptides as potential therapeutics for diabetes and other metabolic diseases

The field of peptide drug research has experienced notable progress, with stapled peptides featuring stabilized α-helical conformation, emerging as a promising field. These peptides offer enhanced stability, cellular permeability, and binding affinity and exhibit potential in the treatment of diabetes and metabolic disorders. Stapled peptides, through the disruption of protein-protein interactions, present varied functionalities encompassing agonism, antagonism, and dual-agonism. This comprehensive review offers insight into the technology of peptide stapling and targeting of crucial molecular pathways associated with glucose metabolism, insulin secretion, and food intake. Additionally, we address the challenges in developing stapled peptides, including concerns pertaining to structural stability, peptide helicity, isomer mixture, and potential side effects.

PROTACs in gynecological cancers: Current knowledge and future potential as a treatment strategy

Cancer continues to threaten human health regardless of novel therapeutic options. Over the last two decades, targeted therapy has emerged as a significant advancement in treating malignancies, surpassing standard chemoradiotherapy and surgical procedures. Gynecological malignancies, including cervical, endometrial, and ovarian carcinoma, have a bad prognosis in advanced or metastatic stages and are difficult to treat. The advancements in understanding the molecular pathways behind cancer development offer valuable insights into promising targeted medicines, and researchers have always searched for a superior and safe technique to target cancer-related oncoproteins because of the limited therapeutic benefit, drug resistance, and off-target effects of current targeted treatments. Recently, proteolysis-targeting chimeras (PROTACs) have been developed to selectively degrade proteins using the natural ubiquitin-proteasome system (UPS). These approaches have garnered significant attention in the field of cancer research. The rapid progress in PROTACs has also eased the targeting of various oncoproteins in gynecological cancer. Therefore, this review aims to elucidate the mechanism and research advancements of PROTACs and provide a comprehensive overview of their use in gynecological tumors.

How to target membrane proteins for degradation: Bringing GPCRs into the TPD fold

We are now in the middle of a so-called "fourth wave" of drug innovation: multispecific medicines aimed at diseases and targets previously thought to be "undruggable"; by inducing proximity between two or more proteins, for example, a target and an effector that do not naturally interact, such modalities have potential far beyond the scope of conventional drugs. In particular, targeted protein degradation (TPD) strategies to destroy disease-associated proteins have emerged as an exciting pipeline in drug discovery. Most efforts are focused on intracellular proteins, whereas membrane proteins have been less thoroughly explored despite the fact that they comprise roughly a quarter of the human proteome with G-protein coupled receptors (GPCRs) notably dysregulated in many diseases. Here, we discuss the opportunities and challenges of developing degraders for membrane proteins with a focus on GPCRs. We provide an overview of different TPD platforms in the context of membrane-tethered targets, and we present recent degradation technologies highlighting their potential application to GPCRs.

Fatty acid synthase (FASN) is a tumor-cell-intrinsic metabolic checkpoint restricting T-cell immunity

Fatty acid synthase (FASN)-catalyzed endogenous lipogenesis is a hallmark of cancer metabolism. However, whether FASN is an intrinsic mechanism of tumor cell defense against T cell immunity remains unexplored. To test this hypothesis, here we combined bioinformatic analysis of the FASN-related immune cell landscape, real-time assessment of cell-based immunotherapy efficacy in CRISPR/Cas9-based FASN gene knockout (FASN KO) cell models, and mathematical and mechanistic evaluation of FASN-driven immunoresistance. FASN expression negatively correlates with infiltrating immune cells associated with cancer suppression, cytolytic activity signatures, and HLA-I expression. Cancer cells engineered to carry a loss-of-function mutation in FASN exhibit an enhanced cytolytic response and an accelerated extinction kinetics upon interaction with cytokine-activated T cells. Depletion of FASN results in reduced carrying capacity, accompanied by the suppression of mitochondrial OXPHOS and strong downregulation of electron transport chain complexes. Targeted FASN depletion primes cancer cells for mitochondrial apoptosis as it synergizes with BCL-2/BCL-XL-targeting BH3 mimetics to render cancer cells more susceptible to T-cell-mediated killing. FASN depletion prevents adaptive induction of PD-L1 in response to interferon-gamma and reduces constitutive overexpression of PD-L1 by abolishing PD-L1 post-translational palmitoylation. FASN is a novel tumor cell-intrinsic metabolic checkpoint that restricts T cell immunity and may be exploited to improve the efficacy of T cell-based immunotherapy.

Treating ICB-resistant cancer by inhibiting PD-L1 via DHHC3 degradation induced by cell penetrating peptide-induced chimera conjugates

The current selection of ligands for both proteins of interest (POI) and E3 ubiquitin ligase significantly restricts the scope of targeted protein degradation (TPD) technologies. This study introduces cell-penetrating peptide-induced chimera conjugates (cp-PCCs) targeting the DHHC3 enzyme involved in PD-L1 palmitoylation. This approach disrupts PD-L1's immunosuppressive function, enhancing anti-tumor immunity. We developed cp-PCCs to degrade DHHC3, directly linking DHHC3-mediated PD-L1 palmitoylation to PD-L1 stability on tumor cells. Our research utilized both in vitro assays and in vivo experiments in immune checkpoint blockade-resistant mouse models. We focused on a CRBN-based cp-PCC named PCC16, which demonstrated a DC50 of 102 nmol for DHHC3 degradation and significantly reduced PD-L1 levels. In resistant models, PCC16 not only robustly downregulated PD-L1 but also exhibited substantial anti-tumor activity in vivo without significant toxicity. This outperformed traditional inhibitors, showcasing the potential of cp-PCC technology to bypass current PROTAC limitations. Our findings suggest that cp-PCCs offer a promising method for targeting PD-L1 through DHHC3 inhibition and support their continued exploration as a versatile tool in cancer immunotherapy, especially for tumors resistant to standard treatments.

Short Peptides as Powerful Arsenal for Smart Fighting Cancer

Short peptides have been coming around as a strong weapon in the fight against cancer on all fronts-in immuno-, chemo-, and radiotherapy, and also in combinatorial approaches. Moreover, short peptides have relevance in cancer imaging or 3D culture. Thanks to the natural 'smart' nature of short peptides, their unique structural features, as well as recent progress in biotechnological and bioinformatics development, short peptides are playing an enormous role in evolving cutting-edge strategies. Self-assembling short peptides may create excellent structures to stimulate cytotoxic immune responses, which is essential for cancer immunotherapy. Short peptides can help establish versatile strategies with high biosafety and effectiveness. Supramolecular short peptide-based cancer vaccines entered clinical trials. Peptide assemblies can be platforms for the delivery of antigens, adjuvants, immune cells, and/or drugs. Short peptides have been unappreciated, especially in the vaccine aspect. Meanwhile, they still hide the undiscovered unlimited potential. Here, we provide a timely update on this highly active and fast-evolving field.

Biotechnological Advances Utilizing Aptamers and Peptides Refining PD-L1 Targeting

While monoclonal antibodies have shown success in cancer immunotherapy, their limitations prompt exploration of alternative approaches such as aptamers and peptides targeting programmed death ligand 1 (PD-L1). Despite the significance of these biotechnological tools, a comprehensive review encompassing both aptamers and peptides for PD-L1 targeting is lacking. Addressing this gap is crucial for consolidating recent advancements and insights in this field. Biotechnological advances leveraging aptamers and peptides represent a cutting-edge approach in refining the targeting proteins. Our review aims to provide valuable guidance for researchers and clinicians, highlighting the biotechnological advances utilizing aptamers and peptides refining PD-L1 targeting.

Targeted Protein Degradation (TPD) for Immunotherapy: Understanding Proteolysis Targeting Chimera-Driven Ubiquitin-Proteasome Interactions

Targeted protein degradation or TPD, is rapidly emerging as a treatment that utilizes small molecules to degrade proteins that cause diseases. TPD allows for the selective removal of disease-causing proteins, including proteasome-mediated degradation, lysosome-mediated degradation, and autophagy-mediated degradation. This approach has shown great promise in preclinical studies and is now being translated to treat numerous diseases, including neurodegenerative diseases, infectious diseases, and cancer. This review discusses the latest advances in TPD and its potential as a new chemical modality for immunotherapy, with a special focus on the innovative applications and cutting-edge research of PROTACs (Proteolysis TArgeting Chimeras) and their efficient translation from scientific discovery to technological achievements. Our review also addresses the significant obstacles and potential prospects in this domain, while also offering insights into the future of TPD for immunotherapeutic applications.

PTMs of PD-1/PD-L1 and PROTACs application for improving cancer immunotherapy

Immunotherapy has been developed, which harnesses and enhances the innate powers of the immune system to fight disease, particularly cancer. PD-1 (programmed death-1) and PD-L1 (programmed death ligand-1) are key components in the regulation of the immune system, particularly in the context of cancer immunotherapy. PD-1 and PD-L1 are regulated by PTMs, including phosphorylation, ubiquitination, deubiquitination, acetylation, palmitoylation and glycosylation. PROTACs (Proteolysis Targeting Chimeras) are a type of new drug design technology. They are specifically engineered molecules that target specific proteins within a cell for degradation. PROTACs have been designed and demonstrated their inhibitory activity against the PD-1/PD-L1 pathway, and showed their ability to degrade PD-1/PD-L1 proteins. In this review, we describe how PROTACs target PD-1 and PD-L1 proteins to improve the efficacy of immunotherapy. PROTACs could be a novel strategy to combine with radiotherapy, chemotherapy and immunotherapy for cancer patients.

Recent progress in degradation of membrane proteins by PROTACs and alternative targeted protein degradation techniques

Targeted protein degradation (TPD) is one of the key strategies of current targeted cancer therapy, and it can eliminate some of the root causes of cancer, and effectively avoid drug resistance caused by traditional drugs. Proteolysis targeting chimera (PROTAC) is a hot branch of the TPD strategy, and it has been shown to induce the degradation of target proteins by activating the inherent ubiquitin-proteasome system (UPS) in tumor cells. PROTACs have been developed for more than two decades, and some of them have been clinically evaluated. Although most of the proteins degraded by PROTACs are intracellular, degradation of some typical membrane proteins has also been reported, such as epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), programmed death ligand 1 (PD-L1), and G-protein-coupled receptor (GPCR). In addition, some other effective membrane protein-degrading strategies have also emerged, such as antibody-based PROTAC (AbTAC), lysosome targeting chimera (LYTAC), molecular glue, and nanoparticle-based PROTAC (Nano-PROTAC). Herein, we discussed the advantages, disadvantages and potential applications of several important membrane protein degradation techniques. These techniques that we have summarized are insightful in paving the way for future development of more general strategies for membrane protein degradation.