Tumor-intrinsic and immune modulatory roles of receptor-interacting protein kinases

Nanoformula Design for Inducing Non-Apoptotic Cell Death Regulation: A Powerful Booster for Cancer Immunotherapy

Cancer treatment has witnessed revolutionary advancements marked by the emergence of immunotherapy, specifically immune checkpoint blockade (ICB). However, the inherent low immunogenicity of tumor cells and the intricate immunosuppressive network within the tumor microenvironment (TME) pose significant challenges to the further development of immunotherapy. Nanotechnology has ushered in unprecedented opportunities and vast prospects for tumor immunotherapy. Nevertheless, traditional nano-formulations often rely on inducing apoptosis to kill cancer cells, which encounters the issue of immune silencing, hindering effective tumor immune activation. The non-apoptotic modes of regulated cell death (RCD), including pyroptosis, ferroptosis, autophagy, necroptosis, and cuproptosis, have gradually garnered attention. These non-apoptotic cell death pathways can induce effective immunogenic cell death (ICD), enhancing cancer immunotherapy. This review comprehensively explores advanced nano-formulation design strategies and their applications in enhancing cancer immunotherapy by promoting non-apoptotic RCD in recent years. It also discusses the potential advantages of these strategies in inducing tumor-specific non-apoptotic RCD. By deeply understanding the significance of non-apoptotic RCD in synergistic cancer immunotherapy, this article provides valuable insights for developing more advanced nano-delivery systems that can robustly induce highly immunogenic non-apoptotic modes, offering novel research and development avenues to address the clinical challenges encountered by immunotherapy represented by ICB.

Virus-Like Nanotherapeutic for Spatiotemporally Enhancing Antigen Presentation and Cross-Presentation toward Potential Personalized Immunotherapy

One of the major causes of immunotherapy resistance is the loss of major histocompatibility complex class I (MHC-I) molecules in tumor cells or the downregulation of the class I antigen presentation pathway. In this study, a novel virus-like nanotherapeutic (siRNA@HCM) is developed via encapsulating nanosized siRNA nanoparticles in a hybrid membrane comprising a personalized tumor cell membrane and a universal 293T membrane expressing the mutant vesicular stomatitis virus glycoprotein (mVSV-G). Upon intravenous administration, siRNA@HCM accumulates at the tumor site and provides two potent driving forces for antitumor immunity. First, mVSV-G induces the fusion of siRNA@HCM with tumor cell membranes and directly injects siRNAs into the cytoplasm, significantly improving tumor intrinsic MHC-I antigen presentation. Moreover, mVSV-G can promote the maturation of dendritic cells, thereby achieving highly efficient antigen cross-presentation. The results demonstrate that spatiotemporally enhancing tumor intrinsic antigen presentation and cross-presentation via siRNA@HCM can achieve satisfactory antitumor efficacy and excellent biocompatibility. Immune infiltration analysis shows that siRNA@HCM treatment turns cold tumors into hot tumors. In addition, it significantly promotes the therapeutic effect of programmed death-1 inhibitor. In summary, virus-like nanotherapeutics present a promising approach to enhance the antitumor immune response, with distinct advantages for potential personalized therapy and clinical applications.

Cancer Bioenergetics and Tumor Microenvironments-Enhancing Chemotherapeutics and Targeting Resistant Niches through Nanosystems

Cancer is an impending bottleneck in the advanced scientific workflow to achieve diagnostic, prognostic, and therapeutic success. Most cancers are refractory to conventional diagnostic and chemotherapeutics due to their limited targetability, specificity, solubility, and side effects. The inherent ability of each cancer to evolve through various genetic and epigenetic transformations and metabolic reprogramming underlies therapeutic limitations. Though tumor microenvironments (TMEs) are quite well understood in some cancers, each microenvironment differs from the other in internal perturbations and metabolic skew thereby impeding the development of appropriate diagnostics, drugs, vaccines, and therapies. Cancer associated bioenergetics modulations regulate TME, angiogenesis, immune evasion, generation of resistant niches and tumor progression, and a thorough understanding is crucial to the development of metabolic therapies. However, this remains a missing element in cancer theranostics, necessitating the development of modalities that can be adapted for targetability, diagnostics and therapeutics. In this challenging scenario, nanomaterials are modular platforms for understanding TME and achieving successful theranostics. Several nanoscale particles have been successfully researched in animal models, quite a few have reached clinical trials, and some have achieved clinical success. Nanoparticles exhibit an intrinsic capability to interact with diverse biomolecules and modulate their functions. Furthermore, nanoparticles can be functionalized with receptors, modulators, and drugs to facilitate specific targeting with reduced toxicity. This review discusses the current understanding of different theranostic nanosystems, their synthesis, functionalization, and targetability for therapeutic modulation of bioenergetics, and metabolic reprogramming of the cancer microenvironment. We highlight the potential of nanosystems for enhanced chemotherapeutic success emphasizing the questions that remain unanswered.

Programmed Necrosis in Host Defense

Host control over infectious disease relies on the ability of cells in multicellular organisms to detect and defend against pathogens to prevent disease. Evolution affords mammals with a wide variety of independent immune mechanisms to control or eliminate invading infectious agents. Many pathogens acquire functions to deflect these immune mechanisms and promote infection. Following successful invasion of a host, cell autonomous signaling pathways drive the production of inflammatory cytokines, deployment of restriction factors and induction of cell death. Combined, these innate immune mechanisms attract dendritic cells, neutrophils and macrophages as well as innate lymphoid cells such as natural killer cells that all help control infection. Eventually, the development of adaptive pathogen-specific immunity clears infection and provides immune memory of the encounter. For obligate intracellular pathogens such as viruses, diverse cell death pathways make a pivotal contribution to early control by eliminating host cells before progeny are produced. Pro-apoptotic caspase-8 activity (along with caspase-10 in humans) executes extrinsic apoptosis, a nonlytic form of cell death triggered by TNF family death receptors (DRs). Over the past two decades, alternate extrinsic apoptosis and necroptosis outcomes have been described. Programmed necrosis, or necroptosis, occurs when receptor interacting protein kinase 3 (RIPK3) activates mixed lineage kinase-like (MLKL), causing cell leakage. Thus, activation of DRs, toll-like receptors (TLRs) or pathogen sensor Z-nucleic acid binding protein 1 (ZBP1) initiates apoptosis as well as necroptosis if not blocked by virus-encoded inhibitors. Mammalian cell death pathways are blocked by herpesvirus- and poxvirus-encoded cell death suppressors. Growing evidence has revealed the importance of Z-nucleic acid sensor, ZBP1, in the cell autonomous recognition of both DNA and RNA virus infection. This volume will explore the detente between viruses and cells to manage death machinery and avoid elimination to support dissemination within the host animal.

Role of protein phosphorylation in cell signaling, disease, and the intervention therapy

Protein phosphorylation is an important post-transcriptional modification involving an extremely wide range of intracellular signaling transduction pathways, making it an important therapeutic target for disease intervention. At present, numerous drugs targeting protein phosphorylation have been developed for the treatment of various diseases including malignant tumors, neurological diseases, infectious diseases, and immune diseases. In this review article, we analyzed 303 small-molecule protein phosphorylation kinase inhibitors (PKIs) registered and participated in clinical research obtained in a database named Protein Kinase Inhibitor Database (PKIDB), including 68 drugs approved by the Food and Drug Administration of the United States. Based on previous classifications of kinases, we divided these human protein phosphorylation kinases into eight groups and nearly 50 families, and delineated their main regulatory pathways, upstream and downstream targets. These groups include: protein kinase A, G, and C (AGC) and receptor guanylate cyclase (RGC) group, calmodulin-dependent protein kinase (CaMK) group, CMGC [Cyclin-dependent kinases (CDKs), Mitogen-activated protein kinases (MAPKs), Glycogen synthase kinases (GSKs), and Cdc2-like kinases (CLKs)] group, sterile (STE)-MAPKs group, tyrosine kinases (TK) group, tyrosine kinase-like (TKL) group, atypical group, and other groups. Different groups and families of inhibitors stimulate or inhibit others, forming an intricate molecular signaling regulatory network. This review takes newly developed new PKIs as breakthrough point, aiming to clarify the regulatory network and relationship of each pathway, as well as their roles in disease intervention, and provide a direction for future drug development.

Necroptosis at a glance

Necroptosis, or programmed necrosis, is an inflammatory form of cell death with important functions in host defense against pathogens and tissue homeostasis. The four cytosolic receptor-interacting protein kinase homotypic interaction motif (RHIM)-containing adaptor proteins RIPK1, RIPK3, TRIF (also known as TICAM1) and ZBP1 mediate necroptosis induction in response to infection and cytokine or innate immune receptor activation. Activation of the RHIM adaptors leads to phosphorylation, oligomerization and membrane targeting of the necroptosis effector protein mixed lineage kinase domain-like (MLKL). Active MLKL induces lesions on the plasma membrane, leading to the release of pro-inflammatory damage-associated molecular patterns (DAMPs). Thus, activities of the RHIM adaptors and MLKL are tightly regulated by posttranslational modifications to prevent inadvertent release of immunogenic contents. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of the regulatory mechanisms of necroptosis and its biological functions in tissue homeostasis, pathogen infection and other inflammatory diseases.

Hydrogen Sulfide Suppresses Skin Fibroblast Proliferation via Oxidative Stress Alleviation and Necroptosis Inhibition

Keloid is a common dermatofibrotic disease with excessive skin fibroblast proliferation. Hydrogen sulfide (H₂S) as the third gasotransmitter improves fibrosis of various organs and tissues. Our study is aimed at investigating the effects and possible mechanisms of H₂S on skin fibroblast proliferation. Scar tissues from six patients with keloid and discarded skin tissue from six normal control patients were collected after surgery, respectively. Plasma H₂S content and skin H₂S production in patients with keloid were measured. Keloid fibroblasts and transforming growth factor-β₁- (TGF-β₁, 10 ng/mL) stimulated normal skin fibroblasts were pretreated with H₂S donor as NaHS (50 μM) for 4 h. Cell migration after scratch was assessed. The expressions of α-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), collagen I, and collagen III were detected by immunofluorescence, real-time PCR, and/or Western blot. Intracellular superoxide anion and mitochondrial superoxide were evaluated by dihydroethidium (DHE) and MitoSOX staining, respectively. Mitochondrial membrane potential was detected by JC-1 staining. Apoptotic cells were detected by TDT-mediated dUTP nick end labeling (TUNEL). The expressions of receptor interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL) were measured by Western blot. We found that H₂S production was impaired in both the plasma and skin of patients with keloid. In keloid fibroblasts and TGF-β₁-stimulated normal skin fibroblasts, exogenous H₂S supplementation suppressed the expressions of α-SMA, PCNA, collagen I, and collagen III, reduced intracellular superoxide anion and mitochondrial superoxide, improved the mitochondrial membrane potential, decreased the positive rate of TUNEL staining, and inhibited RIPK1 and RIPK3 expression as well as MLKL phosphorylation. Overall, H₂S suppressed skin fibroblast proliferation via oxidative stress alleviation and necroptosis inhibition.

Autophagy, ferroptosis, pyroptosis, and necroptosis in tumor immunotherapy

In recent years, immunotherapy represented by immune checkpoint inhibitors (ICIs) has led to unprecedented breakthroughs in cancer treatment. However, the fact that many tumors respond poorly or even not to ICIs, partly caused by the absence of tumor-infiltrating lymphocytes (TILs), significantly limits the application of ICIs. Converting these immune “cold” tumors into “hot” tumors that may respond to ICIs is an unsolved question in cancer immunotherapy. Since it is a general characteristic of cancers to resist apoptosis, induction of non-apoptotic regulated cell death (RCD) is emerging as a new cancer treatment strategy. Recently, several studies have revealed the interaction between non-apoptotic RCD and antitumor immunity. Specifically, autophagy, ferroptosis, pyroptosis, and necroptosis exhibit synergistic antitumor immune responses while possibly exerting inhibitory effects on antitumor immune responses. Thus, targeted therapies (inducers or inhibitors) against autophagy, ferroptosis, pyroptosis, and necroptosis in combination with immunotherapy may exert potent antitumor activity, even in tumors resistant to ICIs. This review summarizes the multilevel relationship between antitumor immunity and non-apoptotic RCD, including autophagy, ferroptosis, pyroptosis, and necroptosis, and the potential targeting application of non-apoptotic RCD to improve the efficacy of immunotherapy in malignancy.