CLytA-DAAO, Free and Immobilized in Magnetic Nanoparticles, induces Cell Death in Human Cancer Cells

Opportunities for nanomaterials in enzyme therapy

In recent years, enzyme therapy strategies have rapidly evolved to catalyze essential biochemical reactions with therapeutic potential. These approaches hold particular promise in addressing rare genetic disorders, cancer treatment, neurodegenerative conditions, wound healing, inflammation management, and infectious disease control, among others. There are several primary reasons for the utilization of enzymes as therapeutics: their substrate specificity, their biological compatibility, and their ability to generate a high number of product molecules per enzyme unit. These features have encouraged their application in enzyme replacement therapy where the enzyme serves as the therapeutic agent to rectify abnormal metabolic and physiological processes, enzyme prodrug therapy where the enzyme initiates a clinical effect by activating prodrugs, and enzyme dynamic or starving therapy where the enzyme acts upon host substrate molecules. Currently, there are >20 commercialized products based on therapeutic enzymes, but approval rates are considerably lower than other biologicals. This has stimulated nanobiotechnology in the last years to develop nanoparticle-based solutions that integrate therapeutic enzymes. This approach aims to enhance stability, prevent rapid clearance, reduce immunogenicity, and even enable spatio-temporal activation of the therapeutic catalyst. This comprehensive review delves into emerging trends in the application of therapeutic enzymes, with a particular emphasis on the synergistic opportunities presented by incorporating enzymes into nanomaterials. Such integration holds the promise of enhancing existing therapies or even paving the way for innovative nanotherapeutic approaches.

Citrullinating enzyme PADI4 and transcriptional repressor RING1B bind in cancer cells

Polycomb groups (PcGs) are transcriptional repressors, formed by a complex of several proteins, involved in multicellular development and cancer epigenetics. One of these proteins is the E3 ubiquitin-protein ligase RING1 (or RING1B), associated with the regulation of transcriptional repression and responsible for monoubiquitylation of the histone H2A. On the other hand, PADI4 is one of the human isoforms of a family of enzymes implicated in the conversion of arginine to citrulline, and it is also involved in the development of glioblastoma, among other types of cancers. In this work, we showed the association of PADI4 and RING1B in the nucleus and cytosol in several cancer cell lines by using immunofluorescence and proximity ligation assays. Furthermore, we demonstrated that binding was hampered in the presence of GSK484, an enzymatic PADI4 inhibitor, suggesting that RING1B could bind to the active site of PADI4, as confirmed by protein-protein docking simulations. In vitro and in silico findings showed that binding to PADI4 occurred for the isolated fragments corresponding to both the N-terminal (residues 1-221) and C-terminal (residues 228-336) regions of RING1B. Binding to PADI4 was also hampered by GSK484, as shown by isothermal titration calorimetry (ITC) experiments for the sole N-terminal region, and by both NMR and ITC for the C-terminal one. The dissociation constants between PADI4 and any of the two isolated RING1B fragments were in the low micromolar range (~2-10 μM), as measured by fluorescence and ITC. The interaction between RING1B and PADI4 might imply citrullination of the former, leading to several biological consequences, as well as being of potential therapeutic relevance for improving cancer treatment with the generation of new antigens.

Nutrition Risk Screening 2002 for Adult Cancer Patients: A Systematic Review and Meta-Analysis

It is critical to screen and assess malnutrition in cancer patients early. However, there is no uniform standard for nutritional risk screening and malnutrition assessment. We aimed to analyze the effects of the Nutrition Risk Screening 2002 (NRS2002) in screening for nutritional risk among adult cancer patients, using the Patient-Generated Subjective Global Assessment (PG-SGA) as the reference standard. A systematic search was performed using PubMed, Embase, Web of Science, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang Database, and China Science and Technology Journal Database (VIP). Studies comparing NRS2002 with PG-SGA in adult cancer patients were included. To assess the quality of the included studies, the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used. The combined sensitivity, specificity, diagnostic odds ratio (DOR), and the area under the receiver-operating characteristic curve (AUC) were calculated. In addition, sensitivity, subgroup, and publication bias analyses were performed. Thirteen articles involving 3,373 participants were included. The combined sensitivity, specificity, DOR, and AUC were 0.62 (95% CI, 0.60-0.64), 0.86 (95% CI, 0.84-0.88), 11.23 (95% CI, 8.26-15.27), and 0.85 (95% CI, 0.82-0.88), respectively. For adult cancer patients, NRS2002 has moderate sensitivity, high specificity, and high AUC in screening for nutritional risk.

Oxygen-consumption based quantification of chemogenetic H2O2 production in live human cells

Reactive Oxygen Species (ROS) in the form of H2O2 can act both as physiological signaling molecules as well as damaging agents, depending on their concentration and localization. The downstream biological effects of H2O2 were often studied making use of exogenously added H2O2, generally as a bolus and at supraphysiological levels. But this does not mimic the continuous, low levels of intracellular H2O2 production by for instance mitochondrial respiration. The enzyme d-Amino Acid Oxidase (DAAO) catalyzes H2O2 formation using d-amino acids, which are absent from culture media, as a substrate. Ectopic expression of DAAO has recently been used in several studies to produce inducible and titratable intracellular H2O2. However, a method to directly quantify the amount of H2O2 produced by DAAO has been lacking, making it difficult to assess whether observed phenotypes are the result of physiological or artificially high levels of H2O2. Here we describe a simple assay to directly quantify DAAO activity by measuring the oxygen consumed during H2O2 production. The oxygen consumption rate (OCR) of DAAO can directly be compared to the basal mitochondrial respiration in the same assay, to estimate whether the ensuing level of H2O2 production is within the range of physiological mitochondrial ROS production. In the tested monoclonal RPE1-hTERT cells, addition of 5 mM d-Ala to the culture media amounts to a DAAO-dependent OCR that surpasses ∼5% of the OCR that stems from basal mitochondrial respiration and hence produces supra-physiological levels of H2O2. We show that the assay can also be used to select clones that express differentially localized DAAO with the same absolute level of H2O2 production to be able to discriminate the effects of H2O2 production at different subcellular locations from differences in total oxidative burden. This method therefore greatly improves the interpretation and applicability of DAAO-based models, thereby moving the redox biology field forward.

The intrinsically disordered, epigenetic factor RYBP binds to the citrullinating enzyme PADI4 in cancer cells

RYBP (Ring1 and YY 1 binding protein) is a multifunctional, intrinsically disordered protein (IDP), best described as a transcriptional regulator. It exhibits a ubiquitin-binding functionality, binds to other transcription factors, and has a key role during embryonic development. RYBP, which folds upon binding to DNA, has a Zn-finger domain at its N-terminal region. By contrast, PADI4 is a well-folded protein and it is one the human isoforms of a family of enzymes implicated in the conversion of arginine to citrulline. As both proteins intervene in signaling pathways related to cancer development and are found in the same localizations within the cell, we hypothesized they may interact. We observed their association in the nucleus and cytosol in several cancer cell lines, by using immunofluorescence (IF) and proximity ligation assays (PLAs). Binding also occurred in vitro, as measured by isothermal titration calorimetry (ITC) and fluorescence, with a low micromolar affinity (~1 μM). AlphaFold2-multimer (AF2) results indicate that PADI4's catalytic domain interacts with the Arg53 of RYBP docking into its active site. As RYBP sensitizes cells to PARP (Poly (ADP-ribose) polymerase) inhibitors, we applied them in combination with an enzymatic inhibitor of PADI4 observing a change in cell proliferation, and the hampering of the interaction of both proteins. This study unveils for the first time the possible citrullination of an IDP, and suggests that this new interaction, whether it involves or not citrullination of RYBP, might have implications in cancer development and progression.

The D-amino acid oxidase-carbon nanotubes: evaluation of cytotoxicity and biocompatibility of a potential anticancer nanosystem

The 'enzyme prodrug therapy' represents a promising strategy to overcome limitations of current cancer treatments by the systemic administration of prodrugs, converted by a foreign enzyme into an active anticancer compound directly in tumor sites. One example is D-amino acid oxidase (DAAO), a dimeric flavoenzyme able to catalyze the oxidative deamination of D-amino acids with production of hydrogen peroxide, a reactive oxygen species (ROS), able to favor cancer cells death. A DAAO variant containing five aminoacidic substitutions (mDAAO) was demonstrated to possess a better therapeutic efficacy under low O2 concentration than wild-type DAAO (wtDAAO). Recently, aiming to design promising nanocarriers for DAAO, multi-walled carbon nanotubes (MWCNTs) were functionalized with polyethylene glycol (PEG) to reduce their tendency to aggregation and to improve their biocompatibility. Here, wtDAAO and mDAAO were adsorbed on PEGylated MWCNTs and their activity and cytotoxicity were tested. While PEG-MWCNTs-DAAOs have shown a higher activity than pristine MWCNTs-DAAO (independently on the DAAO variant used), PEG-MWCNTs-mDAAO showed a higher cytotoxicity than PEG-MWCNTs-wtDAAO at low O2 concentration. In order to evaluate the nanocarriers' biocompatibility, PEG-MWCNTs-DAAOs were incubated in human serum and the composition of protein corona was investigated via nLC-MS/MS, aiming to characterize both soft and hard coronas. The mDAAO variant has influenced the bio-corona composition in both number of proteins and presence of opsonins and dysopsonins: notably, the soft corona of PEG-MWCNTs-mDAAO contained less proteins and was more enriched in proteins able to inhibit the immune response than PEG-MWCNTs-wtDAAO. Considering the obtained results, the PEGylated MWCNTs conjugated with the mDAAO variant seems a promising candidate for a selective antitumor oxidative therapy: under anoxic-like conditions, this novel drug delivery system showed a remarkable cytotoxic effect controlled by the substrate addition, against different tumor cell lines, and a bio-corona composition devoted to prolong its blood circulation time, thus improving the drug's biodistribution.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03568-1.

Remove, Refine, Reduce: Cell Death in Biological Systems

Cell death is an important biological phenomenon [...].

New therapy for pancreatic cancer based on extracellular vesicles

Pancreatic Ductal Adenocarcinoma (PDAC), is the most common aggressive cancer of the pancreas. The standard care of PDAC includes tumor resection and chemotherapy, but the lack of early diagnosis and the limited response to the treatment worsens the patient's condition. In order to improve the efficiency of chemotherapy, we look for more efficient systems of drug delivery. We isolated and fully characterized small Extracellular Vesicles (EVs) from the RWP-1 cell line. Our study indicates that the direct incubation method was the most efficient loading protocol and that a minimum total amount of drug triggers an effect on tumor cells. Therefore, we loaded the small EVs with two chemotherapeutic drugs (Temozolomide and EPZ015666) by direct incubation method and the amount of drug loaded was measured by high-performance liquid chromatography (HPLC). Finally, we tested their antiproliferative effect on different cancer cell lines. Moreover, the system is highly dependent on the drug structure and therefore RWP-1 small EVs^TMZ were more efficient than RWP-1 small EVs^EPZ015666. RWP-1 derived small EVs represent a promising drug delivery tool that can be further investigated in preclinical studies and its combination with PRMT5 inhibitor can be potentially developed in clinical trials for the treatment of PDAC.

Glioblastoma-Derived Small Extracellular Vesicles: Nanoparticles for Glioma Treatment

Glioblastoma (GBM), characterized by fast growth and invasion into adjacent tissue, is the most aggressive cancer of brain origin. Current protocols, which include cytotoxic chemotherapeutic agents, effectively treat localized disease; however, these aggressive therapies present side effects due to the high doses administered. Therefore, more efficient ways of drug delivery have been studied to reduce the therapeutic exposure of the patients. We have isolated and fully characterized small extracellular vesicles (EVs) from seven patient-derived GBM cell lines. After loading them with two different drugs, Temozolomide (TMZ) and EPZ015666, we observed a reduction in the total amount of drugs needed to trigger an effect on tumor cells. Moreover, we observed that GBM-derived small EVs, although with lower target specificity, can induce an effect on pancreatic cancer cell death. These results suggest that GBM-derived small EVs represent a promising drug delivery tool for further preclinical studies and potentially for the clinical development of GBM treatments.

Mini Nutritional Assessment for Adult Cancer Patients: A Systematic Review and Meta-Analysis

Early assessment of malnutrition in cancer patients is very important. The Mini Nutritional Assessment (MNA) is often used to assess malnutrition in adult cancer patients. However, the diagnostic values of MNA are controversial. We aimed to analyze the diagnostic values of MNA in assessing malnutrition in adult cancer patients. A systematic search was performed using Embase, Web of Science, PubMed, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang Database, and China Science and Technology Journal Database (VIP). Studies comparing MNA with other tools or criteria in cancer patients were included. The quality of the included studies was assessed by the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). The pooled sensitivity, specificity, the area under the receiver-operating characteristic curve (AUC), and the diagnostic odds ratio (DOR) were calculated using Stata 17.0 and Meta-DiSc1.4. In addition, sensitivity, subgroup, meta-regression, and publication bias analyses were conducted. In total, 11 studies involving 1367 patients involving MNA were included. The pooled sensitivity, specificity, ROC, and DOR were 0.84 (95% CI: 0.81-0.87), 0.66 (95% CI: 0.63-0.69), 0.84 (95% CI: 0.81-0.87), and 16.11 (95% CI: 7.16-36.27), respectively. In the assessment of malnutrition in adult cancer patients, MNA has high sensitivity and moderate specificity.

Biomedical application of small extracellular vesicles in cancer treatment

Extracellular vesicles (EVs) are produced by almost all cell types in vivo or in vitro. Among them, exosomes are small nanovesicles with a lipid bilayer, proteins and RNAs actively involved in cellular communication, suggesting that they may be used both as biomarkers and for therapeutic purposes in diseases such as cancer. Moreover, the idea of using them as drug delivery vehicle arises as a promising field of study. Here, we reviewed recent findings showing the importance of EVs, with special focus in exosomes as biomarkers including the most relevant proteins found in different cancer types and it is discussed the FDA approved tests which use exosomes in clinical practice. Finally, we present an overview of the different chimeric EVs developed in the last few years, demonstrating that they can be conjugate to nanoparticles, biomolecules, cancer drugs, etc., and can be developed for a specific cancer treatment. Additionally, we summarized the clinical trials where EVs are used in the treatment of several cancer types aiming to improve the prognosis of these deadly diseases.

A review of recent advances in magnetic nanoparticle-based theranostics of glioblastoma

Rapid vascular growth, infiltrative cells and high tumor heterogenicity are some glioblastoma multiforme (GBM) characteristics, making it the most lethal form of brain cancer. Low efficacy of the conventional treatment modalities leads to rampant disease progression and a median survival of 15 months. Magnetic nanoparticles (MNPs), due to their unique physical features/inherent abilities, have emerged as a suitable theranostic platform for targeted GBM treatment. Thus, new strategies are being designed to enhance the efficiency of existing therapeutic techniques such as chemotherapy, radiotherapy, and so on, using MNPs. Herein, the limitations of the current therapeutic strategies, the role of MNPs in mitigating those inadequacies, recent advances in the MNP-based theranostics of GBM and possible future directions are discussed.

Dissecting in vivo and in vitro redox responses using chemogenetics

Hydrogen peroxide (H2O2) is the most abundant reactive oxygen species (ROS) within mammalian cells. At low concentrations, H2O2 serves as a versatile cell signaling molecule that mediates vital physiological functions. Yet at higher concentrations, H2O2 can be a toxic molecule by promoting pathological oxidative stress in cells and tissues. Within normal cells, H2O2 is differentially distributed in a variety of subcellular locales. Moreover, many redox-active enzymes and their substrates are themselves differentially distributed within cells. Numerous reports have described the biological and biochemical consequences of adding exogenous H2O2 to cultured cells and tissues, but many of these observations are difficult to interpret: the effects of exogenous H2O2 do not necessarily replicate the cellular responses to endogenous H2O2. In recent years, chemogenetic approaches have been developed to dynamically regulate the abundance of H2O2 in specific subcellular locales. Chemogenetic approaches have been applied in multiple experimental systems, ranging from in vitro studies on the intracellular transport and metabolism of H2O2, all the way to in vivo studies that generate oxidative stress in specific organs in living animals. These chemogenetic approaches have exploited a yeast-derived d-amino acid oxidase (DAAO) that synthesizes H2O2 only in the presence of its d-amino acid substrate. DAAO can be targeted to various subcellular locales, and can be dynamically activated by the addition or withdrawal of its d-amino acid substrate. In addition, recent advances in the development of highly sensitive genetically encoded H2O2 biosensors are providing a better understanding of both physiological and pathological oxidative pathways. This review highlights several applications of DAAO as a chemogenetic tool across a wide range of biological systems, from analyses of subcellular H2O2 metabolism in cells to the development of new disease models caused by oxidative stress in vivo.

Fenton/Fenton-like metal-based nanomaterials combine with oxidase for synergistic tumor therapy

Chemodynamic therapy (CDT) catalyzed by transition metal and starvation therapy catalyzed by intracellular metabolite oxidases are both classic tumor treatments based on nanocatalysts. CDT monotherapy has limitations including low catalytic efficiency of metal ions and insufficient endogenous hydrogen peroxide (H₂O₂). Also, single starvation therapy shows limited ability on resisting tumors. The “metal-oxidase” cascade catalytic system is to introduce intracellular metabolite oxidases into the metal-based nanoplatform, which perfectly solves the shortcomings of the above-mentioned monotherapiesIn this system, oxidases can not only consume tumor nutrients to produce a “starvation effect”, but also provide CDT with sufficient H₂O₂ and a suitable acidic environment, which further promote synergy between CDT and starvation therapy, leading to enhanced antitumor effects. More importantly, the “metal-oxidase” system can be combined with other antitumor therapies (such as photothermal therapy, hypoxia-activated drug therapy, chemotherapy, and immunotherapy) to maximize their antitumor effects. In addition, both metal-based nanoparticles and oxidases can activate tumor immunity through multiple pathways, so the combination of the “metal-oxidase” system with immunotherapy has a powerful synergistic effect. This article firstly introduced the metals which induce CDT and the oxidases which induce starvation therapy and then described the “metal-oxidase” cascade catalytic system in detail. Moreover, we highlight the application of the “metal-oxidase” system in combination with numerous antitumor therapies, especially in combination with immunotherapy, expecting to provide new ideas for tumor treatment.

An antibody-based enzymatic therapy for cancer treatment: The selective localization of D-amino acid oxidase to EDA fibronectin

In order to generate an antibody directed enzyme prodrug therapy, here we designed a chimeric protein by fusing the F8 antibody that recognizes the EDA of fibronectin (expressed on the tumor neovasculature) and an evolved variant of the ROS-generating enzyme D-amino acid oxidase (DAAO). The F8(scFv)-DAAO-Q144R recombinant protein is expressed by both CHO-S and E. coli cells. The F8(scFv)-DAAO-Q144R from E. coli cells is fully soluble, shows a high specific activity, is more thermostable in blood than the native DAAO, possesses a binding affinity for EDA well suited for efficient tumor accumulation, and localizes in tumor tissues. Notably, the F8(scFv)-DAAO-Q144R conjugate generates a stronger cytotoxicity to tumor cells than the native enzyme, especially when an inhibitor of heme oxygenase-1 (HO-1) is used, making it a promising candidate for a selective antitumor oxidative therapy controlled by the substrate addition, in the so called "activity on demand", thus sparing normal tissue from damage.

Magnetic nanoparticles for cancer theranostics: Advances and prospects

Cancer is one of the leading causes of mortality worldwide. Nanoparticles have been broadly studied and emerged as a novel approach in diagnosis and treatment of tumors. Over the last decade, researches have significantly improved magnetic nanoparticle (MNP)'s theranostic potential as nanomedicine for cancer. Newer MNPs have various advantages such as wider operating temperatures, smaller sizes, lower toxicity, simpler preparations and lower production costs. With a series of unique and superior physical and chemical properties, MNPs have great potential in medical applications. In particular, using MNPs as probes for medical imaging and carriers for targeted drug delivery systems. While MNPs are expected to be the future of cancer diagnosis and precision drug delivery, more research is still required to minimize their toxicity and improve their efficacy. An ideal MNP for clinical applications should be precisely engineered to be stable to act as tracers or deliver drugs to the targeted sites, release drug components only at the targeted sites and have minimal health risks. Our review aims to consolidate the recent improvements in MNPs for clinical applications as well as discuss the future research prospects and potential of MNPs in cancer theranostics.

CLytA-DAAO Chimeric Enzyme Bound to Magnetic Nanoparticles. A New Therapeutical Approach for Cancer Patients?

D-amino acid oxidase (DAAO) is an enzyme that catalyzes the oxidation of D-amino acids generating H2O2. The enzymatic chimera formed by DAAO bound to the choline-binding domain of N-acetylmuramoyl-L-alanine amidase (CLytA) induces cytotoxicity in several pancreatic and colorectal carcinoma and glioblastoma cell models. In the current work, we determined whether the effect of CLytA-DAAO immobilized in magnetic nanoparticles, gold nanoparticles, and alginate capsules offered some advantages as compared to the free CLytA-DAAO. Results indicate that the immobilization of CLytA-DAAO in magnetic nanoparticles increases the stability of the enzyme, extending its time of action. Besides, we compared the effect induced by CLytA-DAAO with the direct addition of hydrogen peroxide, demonstrating that the progressive generation of reactive oxygen species by CLytA-DAAO is more effective in inducing cytotoxicity than the direct addition of H2O2. Furthermore, a pilot study has been initiated in biopsies obtained from pancreatic and colorectal carcinoma and glioblastoma patients to evaluate the expression of the main genes involved in resistance to CLytA-DAAO cytotoxicity. Based on our findings, we propose that CLytA-DAAO immobilized in magnetic nanoparticles could be effective in a high percentage of patients and, therefore, be used as an anti-cancer therapy for pancreatic and colorectal carcinoma and glioblastoma.

Cell Death Mechanisms Induced by CLytA-DAAO Chimeric Enzyme in Human Tumor Cell Lines

The combination of the choline binding domain of the amidase N-acetylmuramoyl-L-alanine (CLytA)-D-amino acid oxidase (DAAO) (CLytA-DAAO) and D-Alanine induces cell death in several pancreatic and colorectal carcinoma and glioblastoma cell lines. In glioblastoma cell lines, CLytA-DAAO-induced cell death was inhibited by a pan-caspase inhibitor, suggesting a classical apoptotic cell death. Meanwhile, the cell death induced in pancreatic and colon carcinoma cell lines is some type of programmed necrosis. In this article, we studied the mechanisms that trigger CLytA-DAAO-induced cell death in pancreatic and colorectal carcinoma and glioblastoma cell lines and we acquire a further insight into the necrotic cell death induced in pancreatic and colorectal carcinoma cell lines. We have analyzed the intracellular calcium mobilization, mitochondrial membrane potential, PARP-1 participation and AIF translocation. Although the mitochondrial membrane depolarization plays a crucial role, our results suggest that CLytA-DAAO-induced cell death is context dependent. We have previously detected pancreatic and colorectal carcinoma cell lines (Hs766T and HT-29, respectively) that were resistant to CLytA-DAAO-induced cell death. In this study, we have examined the putative mechanism underlying the resistance in these cell lines, evaluating both detoxification mechanisms and the inflammatory and survival responses. Overall, our results provide a better understanding on the cell death mechanism induced by CLytA-DAAO, a promising therapy against cancer.