Lactate oxidase/catalase-displaying nanoparticles efficiently consume lactate in the tumor microenvironment to effectively suppress tumor growth

Functional co-delivery nanoliposomes based on improving hypoxia for increasing photoimmunotherapy efficacy of cold tumors

Cold tumors lack T cells infiltration and have low immunogenicity, resulting insufficient immunotherapy response. Therefore, how to realize the transformation from cold tumor to hot tumor is an urgent problem to be solved. Photodynamic therapy can induce immunogenic death of tumor cells (ICD) and activate T lymphocytes to produce tumor immune response. However, hypoxia in the cold tumor microenvironment limits the effectiveness of photodynamic therapy. So in this article, MET-HMME/CAT-HMME@Nlip as a functional co-delivery nanoliposomes was constructed based on overcoming the above problems. Firstly, the oxygen-deficient state could be improved by the following two ways, one is catalase loaded in CAT-HMME@Nlip can decompose high concentration hydrogen peroxide to produce oxygen, and the other is metformin loaded in MET-HMME@Nlip can decrease oxygen consumption by inhibiting of mitochondrial respiration. And then with the increase of substrate oxygen concentration, the sensitivity of photodynamic therapy can be greatly improved and the anti-tumor immune response by PDT-induced ICD can also be enhanced obviously. In addition, metformin could act as a small molecule immune checkpoint inhibitor to reduce the expression of PD-L1 on the surface of tumor cells, thereby effectively improving the specific killing ability of cytotoxic T cells to tumor cells which could not only erasing the primary tumor, but also inhibiting the growth of simulated distant tumors through the immune memory function. This study provides a new idea for improving the clinical treatment effect of hypoxic cold tumors, especially for tumors that could not benefit from immunotherapy due to low or no expression of PD-L1 protein on the surface of tumor cells.

Metal nanozymes modulation of reactive oxygen species as promising strategies for cancer therapy

Nanozymes, nanostructured materials emulating natural enzyme activities, exhibit potential in catalyzing reactive oxygen species (ROS) production for cancer treatment. By facilitating oxidative reactions, elevating ROS levels, and influencing the tumor microenvironment (TME), nanozymes foster the eradication of cancer cells. Noteworthy are their superior stability, ease of preservation, and cost-effectiveness compared to natural enzymes, rendering them invaluable for medical applications. This comprehensive review intricately explores the interplay between ROS and tumor therapy, with a focused examination of metal-based nanozyme strategies mitigating tumor hypoxia. It provides nuanced insights into diverse catalytic processes, mechanisms, and surface modifications of various metal nanozymes, shedding light on their role in intra-tumoral ROS generation and applications in antioxidant therapy. The review concludes by delineating specific potential prospects and challenges associated with the burgeoning use of metal nanozymes in future tumor therapies.

Lactate Oxidase Disrupts Lactate-Activated RAS and PI3K Oncogenic Signaling

LOX was recently shown to inhibit cancer cell proliferation and tumor growth. The mechanism of this inhibition, however, has been exclusively attributed to LOX depletion of TME lactate, a cancer cell energy source, and production of H2O2, an oxidative stressor. We report that TME lactate triggers the assembly of the lactate receptor hydroxycarboxylic acid receptor 1 (HCAR1)-associated protein complex, which includes GRB2, SOS1, KRAS, GAB1, and PI3K, for the activation of both the RAS and the PI3K oncogenic signaling pathways in breast cancer (BCa) cells. LOX treatment decreased the levels of the proteins in the protein complex via induction of their proteasomal degradation. In addition, LOX inhibited lactate-stimulated expression of the lactate transporters MCT1 and MCT4. Our data suggest that HCAR1 activation by lactate is crucial for the assembly and function of the RAS and PI3K signaling nexus. Shutting down lactate signaling by disrupting this nexus could be detrimental to cancer cells. HCAR1 is therefore a promising target for the control of the RAS and the PI3K signaling required for BCa progression. Thus, our study provides insights into lactate signaling regulation of cancer progression and extends our understanding of LOX's functional mechanisms that are fundamental for exploring its therapeutic potential.

Advances in H2O2-supplying materials for tumor therapy: synthesis, classification, mechanisms, and applications

Hydrogen peroxide (H2O2) as a reactive oxygen species produced by cellular metabolism can be used in antitumor therapy. However, the concentration of intracellular H2O2 limits its application. Some materials could enhance the concentration of intracellular H2O2 to strengthen antitumor therapy. In this review, the recent advances in H2O2-supplying materials in terms of promoting intracellular H2O2 production and exogenous H2O2 supply are summarized. Then the mechanism of H2O2-supplying materials for tumor therapy is discussed from three aspects: reconstruction of the tumor hypoxia microenvironment, enhancement of oxidative stress, and the intrinsic anti-tumor ability of H2O2-supplying materials. In addition, the application of H2O2-supplying materials for tumor therapy is discussed. Finally, the future of H2O2-supplying materials is presented. This review aims to provide a novel idea for the application of H2O2-supplying materials in tumor therapy.

Sono-Triggered Cascade Lactate Depletion by Semiconducting Polymer Nanoreactors for Cuproptosis-Immunotherapy of Pancreatic Cancer

The high level of lactate in tumor microenvironment not only promotes tumor development and metastasis, but also induces immune escape, which often leads to failures of various tumor therapy strategies. We here report a sono-triggered cascade lactate depletion strategy by using semiconducting polymer nanoreactors (SPNLCu) for cancer cuproptosis-immunotherapy. The SPNLCu mainly contain a semiconducting polymer as sonosensitizer, lactate oxidase (LOx) conjugated via a reactive oxygen species (ROS)-cleavable linker and chelated Cu2+. Upon ultrasound (US) irradiation, the semiconducting polymer generates singlet oxygen (1O2) to cut ROS-cleavable linker to allow the release of LOx that catalyzes lactate depletion to produce hydrogen peroxide (H2O2). The Cu2+ will be reduced to Cu+ in tumor microenvironment, which reacts with the produced H2O2 to obtain hydroxyl radical (⋅OH) that further improves LOx release via destroying ROS-cleavable linkers. As such, sono-triggered cascade release of LOx achieves effective lactate depletion, thus relieving immunosuppressive roles of lactate. Moreover, the toxic Cu+ induces cuproptosis to cause immunogenic cell death (ICD) for activating antitumor immunological effect. SPNLCu are used to treat both subcutaneous and deep-tissue orthotopic pancreatic cancer with observably enhanced efficacy in restricting the tumor growths. This study thus provides a precise and effective lactate depletion tactic for cancer therapy.

Challenges of enzyme therapy: Why two players are better than one

Enzyme-based therapy has garnered significant attention for its current applications in various diseases. Despite the notable advantages associated with the use of enzymes as therapeutic agents, that could have high selectivity, affinity, and specificity for the target, their application faces challenges linked to physico-chemical and pharmacological properties. These limitations can be addressed through the encapsulation of enzymes in nanoplatforms as a comprehensive solution to mitigate their degradation, loss of activity, off-target accumulation, and immunogenicity, thus enhancing bioavailability, therapeutic efficacy, and circulation time, thereby reducing the number of administrations, and ameliorating patient compliance. The exploration of novel nanomedicine-based enzyme therapeutics for the treatment of challenging diseases stands as a paramount goal in the contemporary scientific landscape, but even then it is often not enough. Combining an enzyme with another therapeutic (e.g., a small molecule, another enzyme or protein, a monoclonal antibody, or a nucleic acid) within a single nanocarrier provides innovative multidrug-integrated therapy and ensures that both the actives arrive at the target site and exert their therapeutic effect, leading to synergistic action and superior therapeutic efficacy. Moreover, this strategic approach could be extended to gene therapy, a field that nowadays has gained increasing attention, as enzymes acting at genomic level and nucleic acids may be combined for synergistic therapy. This multicomponent therapeutic approach opens opportunities for promising future developments. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

The PI3K/Akt Pathway and Glucose Metabolism: A Dangerous Liaison in Cancer

Aberrant activation of the PI3K/Akt pathway commonly occurs in cancers and correlates with multiple aspects of malignant progression. In particular, recent evidence suggests that the PI3K/Akt signaling plays a fundamental role in promoting the so-called aerobic glycolysis or Warburg effect, by phosphorylating different nutrient transporters and metabolic enzymes, such as GLUT1, HK2, PFKB3/4 and PKM2, and by regulating various molecular networks and proteins, including mTORC1, GSK3, FOXO transcription factors, MYC and HIF-1α. This leads to a profound reprogramming of cancer metabolism, also impacting on pentose phosphate pathway, mitochondrial oxidative phosphorylation, de novo lipid synthesis and redox homeostasis and thereby allowing the fulfillment of both the catabolic and anabolic demands of tumor cells. The present review discusses the interactions between the PI3K/Akt cascade and its metabolic targets, focusing on their possible therapeutic implications.

Recent progress in lactate oxidase-based drug delivery systems for enhanced cancer therapy

Lactate oxidase (LOX) is a natural enzyme that efficiently consumes lactate. In the presence of oxygen, LOX can catalyse the formation of pyruvate and hydrogen peroxide (H2O2) from lactate. This process led to acidity alleviation, hypoxia, and a further increase in oxidative stress, alleviating the immunosuppressive state of the tumour microenvironment (TME). However, the high cost of LOX preparation and purification, poor stability, and systemic toxicity limited its application in tumour therapy. Therefore, the rational application of drug delivery systems can protect LOX from the organism's environment and maintain its catalytic activity. This paper reviews various LOX-based drug-carrying systems, including inorganic nanocarriers, organic nanocarriers, and inorganic-organic hybrid nanocarriers, as well as other non-nanocarriers, which have been used for tumour therapy in recent years. In addition, this area's challenges and potential for the future are highlighted.

Chrysin Inhibits TAMs-Mediated Autophagy Activation via CDK1/ULK1 Pathway and Reverses TAMs-Mediated Growth-Promoting Effects in Non-Small Cell Lung Cancer

The natural flavonoid compound chrysin has promising anti-tumor effects. In this study, we aimed to investigate the mechanism by which chrysin inhibits the growth of non-small cell lung cancer (NSCLC). Through in vitro cell culture and animal models, we explored the impact of chrysin on the growth of NSCLC cells and the pro-cancer effects of tumor-associated macrophages (TAMs) and their mechanisms. We observed that M2-TAMs significantly promoted the growth and migration of NSCLC cells, while also markedly activating the autophagy level of these cells. Chrysin displayed a significant inhibitory effect on the growth of NSCLC cells, and it could also suppress the pro-cancer effects of M2-TAMs and inhibit their mediated autophagy. Furthermore, combining network pharmacology, we found that chrysin inhibited TAMs-mediated autophagy activation in NSCLC cells through the regulation of the CDK1/ULK1 signaling pathway, rather than the classical mTOR/ULK1 signaling pathway. Our study reveals a novel mechanism by which chrysin inhibits TAMs-mediated autophagy activation in NSCLC cells through the regulation of the CDK1/ULK1 pathway, thereby suppressing NSCLC growth. This discovery not only provides new therapeutic strategies for NSCLC but also opens up new avenues for further research on chrysin.

Low expression of lysosome-related genes KCNE1, NPC2, and SFTPD promote cancer cell proliferation and tumor associated M2 macrophage polarization in lung adenocarcinoma

Background

Recent research has shown that lysosomes play a critical role in the onset and progression of malignancy by regulating tumor cell death through several mechanisms. Nevertheless, the involvement of lysosome-associated genes (LSAGs) in lung adenocarcinoma (LUAD) is still not well understood.

Methods

LSAGs were identified in malignant lung epithelial cells, as well as biologically and functionally annotated by the comprehensive integration of single-cell and bulk RNA-sequencing data. Prognostic characterization of LSAGs was established, of which the accuracy and reliability were assessed by one-way Cox and LASSO regression. Correlations between LSAG properties and immune cell infiltration, chemotherapy, and immunotherapy were analyzed by integrated omics data. Finally, we characterized the expression of three LSAGs (KCNE1, NPC2, and SFTPD) in malignant lung epithelium and assessed their impact on tumor malignancy related phenotypes.

Results

We identified 18 LSAGs associated with prognosis, of which 3 LSAGs were used to construct prognostic models. High-risk patients had worse survival and the model predicted it better than other clinical indicators. Based on the functional enrichment analyses, LSAGs were associated with binding and molecular activity functions, inhibition of DNA damage repair and tumor growth, IL7 signaling pathway, and glycolysis. M0 macrophages and M1 macrophages were substantially enriched in high-risk patients. Conversely, there was a considerable enrichment of resting dendritic cells and M2 macrophages in patients at low risk. We also found that risk scores predicted the outcome of immunotherapy. In vitro, we found that KCNE1, NPC2, and SFTPD were lowly expressed in malignant epithelial cells and patients with low expression of KCNE1, NPC2, and SFTPD had a higher percentage of M2 macrophage infiltration. Overexpression of KCNE1, NPC2, and SFTPD suppressed the proliferation and invasion of malignant cells, and M0 macrophages remarkably reduced M2 macrophage polarization and cellular secretion of pro-tumor cytokines.

Conclusions

We used three LASGs-KCNE1, NPC2, and SFTPD-to develop and validate a predictive signature for LUAD patients. Furthermore, we found that low expression of KCNE1, NPC2, and SFTPD promotes lung cancer cell proliferation and invasion and M2 macrophage polarization. Our study may provide fresh perspectives for customized immunotherapy.

Emerging nanomaterials targeting macrophage adapted to abnormal metabolism in cancer and atherosclerosis therapy (Review)

Macrophages, as highly heterogeneous and plastic immune cells, occupy a pivotal role in both pro‑inflammatory (M1) and anti‑inflammatory (M2) responses. While M1‑type macrophages secrete pro‑inflammatory factors to initiate and sustain inflammation, M2‑type macrophages promote inflammation regression and uphold tissue homeostasis. These distinct phenotypic transitions in macrophages are closely linked to significant alterations in cellular metabolism, encompassing key response pathways such as glycolysis, pentose phosphate pathway, oxidative phosphorylation, lipid metabolism, amino acid metabolism, the tricarboxylic acid cycle and iron metabolism. These metabolic adaptations enable macrophages to adapt their activities in response to varying disease microenvironments. Therefore, the present review focused primarily on elucidating the intricate metabolic pathways that underlie macrophage functionality. Subsequently, it offers a comprehensive overview of the current state‑of‑the‑art nanomaterials, highlighting their promising potential in modulating macrophage metabolism to effectively hinder disease progression in both cancer and atherosclerosis.

Pan-Cancer Analysis of the LOX Family Reveals that LOX Affects Tumor Prognosis by Affecting Immune Infiltration

The lysyl oxidase (LOX) gene family encodes for a group of copper-dependent enzymes that play a crucial role in the cross-linking of collagen and elastin fibers in the extracellular matrix (ECM). Dysregulation of LOX gene expression has been implicated in various pathological conditions, including cancer. Several studies have shown that the LOX gene family is involved in cancer progression and metastasis. The goal of this article is to conduct a comprehensive analysis of the LOX family's role in pan-cancer multiplexes. We utilized pan-cancer multi-omics sequencing data from TCGA to investigate the relationship between LOX family genes and tumors at four different levels: mutation, copy number variation, methylation, and gene expression. In addition, we also examined the relationship between LOX family genes and tumors at the cell line level using tumor cell line sequencing data from CCLE. Taking into account the impact of LOX family genes on lung cancer, we developed a LOX family lung cancer prognostic model to forecast the disease's prognosis. Our findings revealed that LOXL2 had the highest mutation frequency in tumors, while all four LOX family genes experienced some degree of copy number variation in diverse tumors. We observed that LOX, LOXL1 to LOXL3 were predominantly highly expressed in tumors including LUAD. The expression trends of LOX and LOXL1 to LOXL3 were consistent across tumor cell lines, but differed somewhat from LOXL4. Utilizing 25 LOX family-related genes, we constructed a LOX family prognostic model that performed well in predicting the prognosis of lung cancer. Through pan-cancer analysis, we gain further knowledge of the role of LOX family genes in different tumors, offering a novel pathway for future research into the relationship between LOX family genes and tumors.

Current Advances on Nanomaterials Interfering with Lactate Metabolism for Tumor Therapy

Increasing numbers of studies have shown that tumor cells prefer fermentative glycolysis over oxidative phosphorylation to provide a vast amount of energy for fast proliferation even under oxygen-sufficient conditions. This metabolic alteration not only favors tumor cell progression and metastasis but also increases lactate accumulation in solid tumors. In addition to serving as a byproduct of glycolytic tumor cells, lactate also plays a central role in the construction of acidic and immunosuppressive tumor microenvironment, resulting in therapeutic tolerance. Recently, targeted drug delivery and inherent therapeutic properties of nanomaterials have attracted great attention, and research on modulating lactate metabolism based on nanomaterials to enhance antitumor therapy has exploded. In this review, the advanced tumor therapy strategies based on nanomaterials that interfere with lactate metabolism are discussed, including inhibiting lactate anabolism, promoting lactate catabolism, and disrupting the "lactate shuttle". Furthermore, recent advances in combining lactate metabolism modulation with other therapies, including chemotherapy, immunotherapy, photothermal therapy, and reactive oxygen species-related therapies, etc., which have achieved cooperatively enhanced therapeutic outcomes, are summarized. Finally, foreseeable challenges and prospective developments are also reviewed for the future development of this field.

Tumor Microenvironment Heterogeneity, Potential Therapeutic Avenues, and Emerging Therapies

OBJECTIVE

This review describes the comprehensive portrait of tumor microenvironment (TME). Additionally, we provided a panoramic perspective on the transformation and functions of the diverse constituents in TME, and the underlying mechanisms of drug resistance, beginning with the immune cells and metabolic dynamics within TME. Lastly, we summarized the most auspicious potential therapeutic strategies.

RESULTS

TME is a unique realm crafted by malignant cells to withstand the onslaught of endogenous and exogenous therapies. Recent research has revealed many small-molecule immunotherapies exhibiting auspicious outcomes in preclinical investigations. Furthermore, some pro-immune mechanisms have emerged as a potential avenue. With the advent of nanosystems and precision targeting, targeted therapy has now transcended the "comfort zone" erected by cancer cells within TME.

CONCLUSION

The ceaseless metamorphosis of TME fosters the intransigent resilience and proliferation of tumors. However, existing therapies have yet to surmount the formidable obstacles posed by TME. Therefore, scientists should investigate potential avenues for therapeutic intervention and design innovative pharmacological and clinical technologies.

Potential targeting of the tumor microenvironment to improve cancer virotherapy

In 2015, oncolytic virotherapy was approved for clinical use, and in 2017, recombinant adeno-associated virus (AAV) delivery was also approved. However, systemic administration remains challenging due to the limited number of viruses that successfully reach the target site. Although the US Food and Drug Administration (FDA) permits the use of higher doses of AAV to achieve greater rates of transduction, most AAV still accumulates in the liver, potentially leading to toxicity there and elsewhere. Targeting the tumor microenvironment is a promising strategy for cancer treatment due to the critical role of the tumor microenvironment in controlling tumor progression and influencing the response to therapies. Newly discovered evidence indicates that administration routes focusing on the tumor microenvironment can promote delivery specificity and transduction efficacy within the tumor. Here, we review approaches that involve modifying viral surface features, modulating the immune system, and targeting the physicochemical characteristics in tumor microenvironment to regulate therapeutic delivery. Targeting tumor acidosis presents advantages that can be leveraged to enhance virotherapy outcomes and to develop new therapeutic approaches that can be integrated with standard treatments.

Lactate oxidase/vSIRPα conjugates efficiently consume tumor-produced lactates and locally produce tumor-necrotic H2O2 to suppress tumor growth

Aggressive tumor formation often leads to excessive anaerobic glycolysis and massive production and accumulation of lactate in the tumor microenvironment (TME). To significantly curb lactate accumulation in TME, in this study, lactate oxidase (LOX) was used as a potential therapeutic enzyme and signal regulatory protein α variant (vSIRPα) as a tumor cell targeting ligand. SpyCatcher protein and SpyTag peptide were genetically fused to LOX and vSIRPα, respectively, to form SC-LOX and ST-vSIRPα and tumor-targeting LOX/vSIRPα conjugates were constructed via a SpyCatcher/SpyTag protein ligation system. LOX/vSIRPα conjugates selectively bound to the CD47-overexpressing mouse melanoma B16-F10 cells and effectively consumed lactate produced by the B16-F10 cells, generating adequate amounts of hydrogen peroxide (H₂O₂), which induces drastic necrotic tumor cell death. Local treatments of B16-F10 tumor-bearing mice with LOX/vSIRPα conjugates significantly suppressed B16-F10 tumor growth in vivo without any severe side effects. Tumor-targeting vSIRPα may allow longer retention of LOX in tumor sites, effectively consuming surrounding lactate in TME and locally generating adequate amounts of cytotoxic H₂O₂ to suppress tumor growth. The approach restraining the local lactate concentration and H₂O₂ in TME using LOX and vSIRPα could offer new opportunities for developing enzyme/targeting ligand conjugate-based therapeutic tools for tumor treatment.

Qigong Exercise Balances Oxygen Supply and Acid-Base to Modulate Hypoxia: A Perspective Platform toward Preemptive Health & Medicine

Qigong is a meditative movement with therapeutic effects and is commonly practiced in Eastern medicine. A growing body of evidence validates its health benefits, leading to mechanistic questions about how it works. We propose a novel mechanism by which the “acid” caused by hypoxia affects metabolism, and the way it is neutralized through Qigong practice involves the body’s blood flow and vasculature modifications. Specifically, Qigong exercise generates an oxygen supply and acid-base balance against the hypoxic effects of underlying pathological conditions. We also propose that Qigong exercise mediated and focused on the local hypoxia environment of tissues might normalize the circulation of metabolic and inflammation accumulation in the tumor tissue and restore the normal metabolism of tissues and cells through calm, relaxation, and extreme Zen-style breathing that gravitates toward preemptive health and medicine. Thus, we propose the mechanisms of action related to Qigong, intending to unify Eastern and Western exercise theory.

How Warburg-Associated Lactic Acidosis Rewires Cancer Cell Energy Metabolism to Resist Glucose Deprivation

Lactic acidosis, a hallmark of solid tumour microenvironment, originates from lactate hyperproduction and its co-secretion with protons by cancer cells displaying the Warburg effect. Long considered a side effect of cancer metabolism, lactic acidosis is now known to play a major role in tumour physiology, aggressiveness and treatment efficiency. Growing evidence shows that it promotes cancer cell resistance to glucose deprivation, a common feature of tumours. Here we review the current understanding of how extracellular lactate and acidosis, acting as a combination of enzymatic inhibitors, signal, and nutrient, switch cancer cell metabolism from the Warburg effect to an oxidative metabolic phenotype, which allows cancer cells to withstand glucose deprivation, and makes lactic acidosis a promising anticancer target. We also discuss how the evidence about lactic acidosis' effect could be integrated in the understanding of the whole-tumour metabolism and what perspectives it opens up for future research.