Bump-and-Hole Engineering Identifies Specific Substrates of Glycosyltransferases in Living Cells.

Studying posttranslational modifications classically relies on experimental strategies that oversimplify the complex biosynthetic machineries of living cells. Protein glycosylation contributes to essential biological processes, but correlating glycan structure, underlying protein, and disease-relevant biosynthetic regulation is currently elusive. Here, we engineer living cells to tag glycans with editable chemical functionalities while providing information on biosynthesis, physiological context, and glycan fine structure. We introduce a non-natural substrate biosynthetic pathway and use engineered glycosyltransferases to incorporate chemically tagged sugars into the cell surface glycome of the living cell. We apply the strategy to a particularly redundant yet disease-relevant human glycosyltransferase family, the polypeptide N-acetylgalactosaminyl transferases. This approach bestows a gain-of-chemical-functionality modification on cells, where the products of individual glycosyltransferases can be selectively characterized or manipulated to understand glycan contribution to major physiological processes.

Metabolic precision labeling enables selective probing of O-linked N-acetylgalactosamine glycosylation.

Protein glycosylation events that happen early in the secretory pathway are often dysregulated during tumorigenesis. These events can be probed, in principle, by monosaccharides with bioorthogonal tags that would ideally be specific for distinct glycan subtypes. However, metabolic interconversion into other monosaccharides drastically reduces such specificity in the living cell. Here, we use a structure-based design process to develop the monosaccharide probe N-(S)-azidopropionylgalactosamine (GalNAzMe) that is specific for cancer-relevant Ser/Thr(O)-linked N-acetylgalactosamine (GalNAc) glycosylation. By virtue of a branched N-acylamide side chain, GalNAzMe is not interconverted by epimerization to the corresponding N-acetylglucosamine analog by the epimerase N-acetylgalactosamine-4-epimerase (GALE) like conventional GalNAc-based probes. GalNAzMe enters O-GalNAc glycosylation but does not enter other major cell surface glycan types including Asn(N)-linked glycans. We transfect cells with the engineered pyrophosphorylase mut-AGX1 to biosynthesize the nucleotide-sugar donor uridine diphosphate (UDP)-GalNAzMe from a sugar-1-phosphate precursor. Tagged with a bioorthogonal azide group, GalNAzMe serves as an O-glycan-specific reporter in superresolution microscopy, chemical glycoproteomics, a genome-wide CRISPR-knockout (CRISPR-KO) screen, and imaging of intestinal organoids. Additional ectopic expression of an engineered glycosyltransferase, "bump-and-hole" (BH)-GalNAc-T2, boosts labeling in a programmable fashion by increasing incorporation of GalNAzMe into the cell surface glycoproteome. Alleviating the need for GALE-KO cells in metabolic labeling experiments, GalNAzMe is a precision tool that allows a detailed view into the biology of a major type of cancer-relevant protein glycosylation.

Finite element analyses of lateral condyle fracture fixation in paediatrics regarding configuration of Kirschner-wire.

BACKGROUND: This study aimed to discover the most stable outcome among different Kirschner-wire (K-wire) configurations for fixation of a lateral condyle fracture (Milch type II) in different loads of stress by using finite element analyses (FEA). METHODS: The right humerus of a 6-year-old boy with a lateral condyle fracture (Milch type II), was modelled with a computer aided engineering. Using FEA, peak von Mises stress and stiffness were evaluated first for a single K-wire fixation by varying the angle (0, 5, 10, 15, 20, 25, 30 degrees). Then, based on the single K-wire result, assessment of peak von Mises stress and stiffness were evaluated via FEA for two- or three-wire fixation under various configurations (two convergent, two parallel, three divergent). RESULTS: Single K-wire fixation by 5 and 25 degrees had the lowest peak von Mises stress. The fracture site showed higher stiffness at 0, 5 and 15 degrees. Considering the collected results and clinical situation, 5 degree K-wire was selected for the FEA of multiple K-wire fixation. For multiple K-wire fixation, three divergent (5-20-35 degrees) K-wires showed better stability, both in peak von Mises stress and stiffness, than any two-K-wire configurations. Among two K-wire fixations, two divergent (5-50 degrees) K-wires provided the lowest von Mises stress in varus and valgus while two divergent (5-65 degrees) K-wires showed better results in flexion, extension, internal and external rotation, and both configurations showed similar results in stiffness. CONCLUSIONS: We successfully created a paediatric lateral condyle fracture (Milch type II) model which was used to conduct FEA on different K-wire configurations to achieve stability of the fracture. Our results show that an initial K-wire inserted at 5 degrees, followed by the insertion of a second divergent wire at either 45 or 60 degrees provides the most stability in two K-wire fixations in this type of fracture repair.

Effect of the Duration of NSAID Use on COVID-19.

Background and Objectives: Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used to control pain and fever. However, their effect on COVID-19 infected patients has not been fully studied. In this study, we investigated the effect of the duration of NSAIDs use on COVID-19 infection and clinical outcomes. Materials and Methods: In South Korea, 25,739 eligible patients who received COVID-19 testing between 1 January and 31 July 2020, were included in this retrospective observational cohort analysis. Based on the date of the first COVID-19 test for each patient, NSAID prescription dates were used to separate patients into two groups (short-term group: <2 weeks; long-term group: 8−12 weeks). COVID-19 infectivity and clinical outcomes were analyzed. We used the propensity score-matching (PSM) method. Results: Of the 580 patients who had taken NSAIDs before the date of COVID-19 test, 534 and 46 patients were grouped in the short- and long-term NSAID-use groups, respectively. We did not find a statistically significant increased risk of COVID-19 infection (adjustment for age and sex, p = 0.413; adjustment for age, sex, region of residence, comorbidity, Charlson Comorbidity Index, and current use of medication, p = 0.259) or change in clinical outcomes, including conventional oxygen therapy, admission of intensive care unit, artificial ventilation, or death, between the two groups in which the PSM method was applied. Conclusions: The duration of NSAIDs use did not have a statistically significant effect on COVID-19 infectivity or clinical outcomes. However, further studies looking at clinical presentation and laboratory test results in a large number of people should be performed.

Attenuating Effects of Dieckol on Hypertensive Nephropathy in Spontaneously Hypertensive Rats.

Hypertension induces renal fibrosis or tubular interstitial fibrosis, which eventually results in end-stage renal disease. Epithelial-to-mesenchymal transition (EMT) is one of the underlying mechanisms of renal fibrosis. Though previous studies showed that Ecklonia cava extracts (ECE) and dieckol (DK) had inhibitory action on angiotensin (Ang) I-converting enzyme, which converts Ang I to Ang II. It is known that Ang II is involved in renal fibrosis; however, it was not evaluated whether ECE or DK attenuated hypertensive nephropathy by decreasing EMT. In this study, the effect of ECE and DK on decreasing Ang II and its down signal pathway of angiotensin type 1 receptor (AT1R)/TGFß/SMAD, which is related with the EMT and restoring renal function in spontaneously hypertensive rats (SHRs), was investigated. Either ECE or DK significantly decreased the serum level of Ang II in the SHRs. Moreover, the renal expression of AT1R/TGFß/SMAD was decreased by the administration of either ECE or DK. The mesenchymal cell markers in the kidney of SHRs was significantly decreased by ECE or DK. The fibrotic tissue of the kidney of SHRs was also significantly decreased by ECE or DK. The ratio of urine albumin/creatinine of SHRs was significantly decreased by ECE or DK. Overall, the results of this study indicate that ECE and DK decreased the serum levels of Ang II and expression of AT1R/TGFß/SMAD, and then decreased the EMT and renal fibrosis in SHRs. Furthermore, the decrease in EMT and renal fibrosis could lead to the restoration of renal function. It seems that ECE or DK could be beneficial for decreasing hypertensive nephropathy by decreasing EMT and renal fibrosis.

Gamma-aminobutyric acid-salt attenuated high cholesterol/high salt diet induced hypertension in mice.

Excessive salt intake induces hypertension, but several gamma-aminobutyric acid (GABA) supplements have been shown to reduce blood pressure. GABAsalt, a fermented salt by L. brevis BJ20 containing GABA was prepared through the post-fermentation with refined salt and the fermented GABA extract. We evaluated the effect of GABA-salt on hypertension in a high salt, high cholesterol diet induced mouse model. We analyzed type 1 macrophage (M1) polarization, the expression of M1 related cytokines, GABA receptor expression, endothelial cell (EC) dysfunction, vascular smooth muscle cell (VSMC) proliferation, and medial thicknesses in mice model. GABA-salt attenuated diet-induced blood pressure increases, M1 polarization, and TNF-α and inducible nitric oxide synthase (NOS) levels in mouse aortas, and in salt treated macrophages in vitro. Furthermore, GABA-salt induced higher GABAB receptor and endothelial NOS (eNOS) and eNOS phosphorylation levels than those observed in salt treated ECs. In addition, GABA-salt attenuated EC dysfunction by decreasing the levels of adhesion molecules (E-selectin, Intercellular Adhesion Molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1]) and of von Willebrand Factor and reduced EC death. GABA-salt also reduced diet-induced reductions in the levels of eNOS, phosphorylated eNOS, VSMC proliferation and medial thickening in mouse aortic tissues, and attenuated Endothelin-1 levels in salt treated VSMCs. In summary, GABA-salt reduced high salt, high cholesterol diet induced hypertension in our mouse model by reducing M1 polarization, EC dysfunction, and VSMC proliferation.

Radiofrequency irradiation attenuates angiogenesis and inflammation in UVB-induced rosacea in mouse skin.

Rosacea is a skin inflammatory condition accompanied by cutaneous signs such as oedema, flushing, erythema, telangiectasia and pustules. Generally, rosacea is triggered by ultraviolet B (UVB) exposure. When exposed to UVB, skin epidermis thickens and produces elevated levels of pro-inflammatory cytokines, especially keratinocyte-related VEGF, a potent angiogenic factor. The upregulations of VEGF expression and its secretion promote the formation of new blood vessels and exacerbates rosacea. In this study, radiofrequency (RF) irradiation reduced keratinocyte proliferation in the epidermal layer, the expressions of pro-inflammatory cytokines, angiogenesis-related inflammatory factors and VEGF in our UVB-induced model of rosacea in vitro and in vivo. RF irradiation attenuated VEGF-induced angiogenesis-associated processes such as tube formation, cell migration and endothelial cell proliferation. Notably, blood vessel densities in the skins of UVB-treated mice and rosacea patients were significantly decreased by RF irradiation. These results provide experimental and molecular evidence regarding the effectiveness of RF irradiation for the treatment of rosacea.

Engineering Orthogonal Polypeptide GalNAc-Transferase and UDP-Sugar Pairs.

O-Linked α-N-acetylgalactosamine (O-GalNAc) glycans constitute a major part of the human glycome. They are difficult to study because of the complex interplay of 20 distinct glycosyltransferase isoenzymes that initiate this form of glycosylation, the polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). Despite proven disease relevance, correlating the activity of individual GalNAc-Ts with biological function remains challenging due to a lack of tools to probe their substrate specificity in a complex biological environment. Here, we develop a "bump-hole" chemical reporter system for studying GalNAc-T activity in vitro. Individual GalNAc-Ts were rationally engineered to contain an enlarged active site (hole) and probed with a newly synthesized collection of 20 (bumped) uridine diphosphate N-acetylgalactosamine (UDP-GalNAc) analogs to identify enzyme-substrate pairs that retain peptide specificities but are otherwise completely orthogonal to native enzyme-substrate pairs. The approach was applicable to multiple GalNAc-T isoenzymes, including GalNAc-T1 and -T2 that prefer nonglycosylated peptide substrates and GalNAcT-10 that prefers a preglycosylated peptide substrate. A detailed investigation of enzyme kinetics and specificities revealed the robustness of the approach to faithfully report on GalNAc-T activity and paves the way for studying substrate specificities in living systems.

Pyrogallol-Phloroglucinol-6,6-Bieckol Alleviates Obesity and Systemic Inflammation in a Mouse Model by Reducing Expression of RAGE and RAGE Ligands.

Ecklonia cava (E. cava) can alleviate diet-induced obesity in animal models, and phlorotannins contained in E. cava help prevent hypertrophy-induced adipocyte differentiation. Receptor for advanced glycation end-products (RAGE) is well known to induce hypertrophy of visceral fat and to trigger inflammation substantially. While the relationship between RAGE and obesity and inflammation has been well-characterized, few studies describe the effects of phlorotannin on RAGE. In this study, we investigated the anti-obesity effects of pyrogallol-phloroglucinol-6,6-bieckol (PPB)-a single compound from the ethanoic extract of E. cava-mediated by a reduction in the inflammation caused by RAGE and RAGE ligands. In visceral fat, PPB (i) significantly inhibited RAGE ligands, (ii) reduced the expression of RAGE, and (iii) reduced the binding ratio between RAGE and RAGE ligands. Under lower expression of RAGE, RAGE ligands and their cognate binding, the differentiation of macrophages found in visceral fat into M1-type-the pro-inflammatory form of this immune cell-was reduced. As the M1-type macrophage decreased, pro-inflammatory cytokines, which cause obesity, decreased in visceral fat. The results of this study highlight the anti-obesity effects of PPB, with the effects mediated by reductions in RAGE, RAGE ligands, and inflammation.

Effect of Ishophloroglucin A, A Component of Ishige okamurae, on Glucose Homeostasis in the Pancreas and Muscle of High Fat Diet-Fed Mice.

Ishophloroglucin A (IPA), a component of Ishige okamurae (IO), was previously evaluated to standardize the antidiabetic potency of IO. However, the potential of IPA as a functional food for diabetes prevention has not yet been evaluated. Here, we investigated if 1.35 mg/kg IPA, which is the equivalent content of IPA in 75 mg/kg IO, improved glucose homeostasis in high-fat diet (HFD)-induced diabetes after 12 weeks of treatment. IPA significantly ameliorated glucose intolerance, reducing fasting glucose levels as well as 2 h glucose levels in HFD mice. In addition, IPA exerted a protective effect on the pancreatic function in HFD mice via pancreatic ß-cells and C-peptide. The level of glucose transporter 4 (GLUT4) in the muscles of HFD mice was stimulated by IPA intake. Our results suggested that IPA, which is a component of IO, can improve glucose homeostasis via GLUT4 in the muscles of HFD mice. IO may be used as a functional food for the prevention of diabetes.

Phlorotannins from Ecklonia cava Attenuates Palmitate-Induced Endoplasmic Reticulum Stress and Leptin Resistance in Hypothalamic Neurons.

Leptin resistance in the hypothalamus has an essential role in obesity. Saturated fatty acids such as palmitate bind to Toll-like receptor 4 (TLR4) and lead to endoplasmic reticulum (ER) stress and leptin resistance. In this study, we evaluated whether extracts of Ecklonia cava would attenuate the ER stress induced by palmitate and reduce leptin resistance in hypothalamic neurons and microglia. We added palmitate to these cells to mimic the environment induced by high-fat diet in the hypothalamus and evaluated which of the E. cava phlorotannins-dieckol (DK), 2,7-phloroglucinol-6,6-bieckol (PHB), pyrogallol-phloroglucinol-6,6-bieckol (PPB), or phlorofucofuroeckol-A (PFFA)-had the most potent effect on attenuating leptin resistance. TLR4 and NF-κB expression induced by palmitate was attenuated most effectively by PPB in both hypothalamic neurons and microglia. ER stress markers were increased by palmitate and were attenuated by PPB in both hypothalamic neurons and microglia. Leptin resistance, which was evaluated as an increase in SOCS3 and a decrease in STAT3 with leptin receptor expression, was increased by palmitate and was decreased by PPB in hypothalamic neurons. The culture medium from palmitate-treated microglia increased leptin resistance in hypothalamic neurons and this resistance was attenuated by PPB. In conclusion, PPB attenuated leptin resistance by decreasing ER stress in both hypothalamic neurons and microglia.

sRAGE prolonged stem cell survival and suppressed RAGE-related inflammatory cell and T lymphocyte accumulations in an Alzheimer's disease model.

The main causes of Alzheimer's disease (AD) have not determined and effective treatment has not been developed yet, even though extensive researches and several clinical trials have been conducted.. Fortunately, stem cell transplantation is emerging as a potential therapeutic candidate for AD, but the success of stem cell based therapy depends on the survival of transplanted cells. Here, we generated sRAGE secreting mesenchymal stem cells (sRAGE-MSCs) and then injected these MSCs or control MSCs with amyloid beta 1-42 (Aß1-42) into the entorhinal cortices of male Sprague Dawley rats. The survival of transplanted cell, the number of T lymphocytes and microglia, expression of RAGE and its ligands and neuronal cell death were determined, 4 weeks after sRAGE-MSC transplantation. Transplanted sRAGE-MSCs survived longer than control MSCs and sRAGE-MSCs showed reduced level of CD4 and CD3d positive T lymphocyte. Furthermore, the number of M1 microglia in MSCs was more than that of sRAGE-MSCs as well. On the other hand, the number of M2 microglia in sRAGE-MSCs was increased compared with that of MSCs. In addition, sRAGE-MSCs decreased RAGE and RAGE ligand expressions and their interactions more effectively than those of MSCs. Finally, sRAGE-MSC transplantation protected from apoptosis and prevented decreasing numbers of neuron in Aß1-42 treated rat brains. These observations suggest continuous sRAGE secretion from sRAGE-MSCs might appreciably improve the effectiveness of cell therapy in Aß1-42 injected rat brains.

Protection against RAGE-mediated neuronal cell death by sRAGE-secreting human mesenchymal stem cells in 5xFAD transgenic mouse model.

Alzheimer's disease (AD), which is the most commonly encountered neurodegenerative disease, causes synaptic dysfunction and neuronal loss due to various pathological processes that include tau abnormality and amyloid beta (Aß) accumulation. Aß stimulates the secretion and the synthesis of Receptor for Advanced Glycation End products (RAGE) ligand by activating microglial cells, and has been reported to cause neuronal cell death in Aß1-42 treated rats and in mice with neurotoxin-induced Parkinson's disease. The soluble form of RAGE (sRAGE) is known to reduce inflammation, and to decrease microglial cell activation and Aß deposition, and thus, it protects from neuronal cell death in AD. However, sRAGE protein has too a short half-life for therapeutic purposes. We developed sRAGE-secreting umbilical cord derived mesenchymal stem cells (sRAGE-MSCs) to enhance the inhibitory effects of sRAGE on Aß deposition and to reduce the secretion and synthesis of RAGE ligands in 5xFAD mice. In addition, these cells improved the viability of injected MSCs, and enhanced the protective effects of sRAGE by inhibiting the binding of RAGE and RAGE ligands in 5xFAD mice. These findings suggest sRAGE protein from sRAGE-MSCs has better protection against neuronal cell death than sRAGE protein or single MSC treatment by inhibiting the RAGE cell death cascade and RAGE-induce inflammation.

Enantioselective Decarboxylative Arylation of α-Amino Acids via the Merger of Photoredox and Nickel Catalysis.

An asymmetric decarboxylative Csp(3)-Csp(2) cross-coupling has been achieved via the synergistic merger of photoredox and nickel catalysis. This mild, operationally simple protocol transforms a wide variety of naturally abundant α-amino acids and readily available aryl halides into valuable chiral benzylic amines in high enantiomeric excess, thereby producing motifs found in pharmacologically active agents.

Stereoconvergent arylations and alkenylations of unactivated alkyl electrophiles: catalytic enantioselective synthesis of secondary sulfonamides and sulfones.

The development of efficient methods for the generation of enantioenriched sulfonamides and sulfones is an important objective for fields such as organic synthesis and medicinal chemistry; however, there have been relatively few reports of direct catalytic asymmetric approaches to controlling the stereochemistry of the sulfur-bearing carbon of such targets. In this report, we describe nickel-catalyzed stereoconvergent Negishi arylations and alkenylations of racemic α-bromosulfonamides and -sulfones that furnish the desired cross-coupling product in very good ee and yield for an array of reaction partners. Mechanistic studies are consistent with the generation of a radical intermediate that has a sufficient lifetime to diffuse out of the solvent cage and to cyclize onto a pendant olefin.

Asymmetry of peak plantar pressure in transfemoral amputees during indoor and outdoor walking.

This study investigates the differences in peak plantar pressure between the amputated and intact limbs of transfemoral amputees when walking outdoors. Ten non-amputees (aged 24.4 ± 2.0 years, 176.9 ± 2.5 cm, 72.3 ± 7.9 kg) and six transfemoral amputees (48.5 ± 6.3 years, 173.8 ± 4.2 cm, 82.0 ± 11.9 kg) participated in the study. Over approximately 1.6 km, the participants encountered various obstacles, including stairs, uneven surfaces, hills, and level ground, both indoors and outdoors. Throughout the walking session, the peak plantar pressure in both feet was monitored using wearable insole sensors. For all terrains, the percentage asymmetry was determined. Significant changes in peak plantar pressure asymmetry were found between the intact and amputated limbs, particularly when walking on level ground indoors, uneven terrains, descending stairs, and on steep slopes outdoors (all p < 0.05). These findings highlight the greater peak plantar pressure asymmetry in transfemoral amputees when walking outside. In addition, this study revealed that not all terrains contribute uniformly to this asymmetry.

Corrigendum: miR-31-3p functions as a tumor suppressor by directly targeting GABBR2 in prostate cancer.

[This corrects the article DOI: 10.3389/fonc.2022.945057.].

Human Nasal Inferior Turbinate-Derived Neural Stem Cells Improve the Niche of Substantia Nigra Par Compacta in a Parkinson's Disease Model by Modulating Hippo Signaling.

BACKGROUND: Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases, following Alzheimer's disease. The onset of PD is characterized by the loss of dopaminergic neurons in the substantia nigra. Stem cell therapy has great potential for the treatment of neurodegenerative diseases, and human nasal turbinate-derived stem cells (hNTSCs) have been found to share some characteristics with mesenchymal stem cells. Although the Hippo signaling pathway was originally thought to regulate cell size in organs, recent studies have shown that it can also control inflammation in neural cells. METHODS: Dopaminergic neuron-like cells were differentiated from SH-SY5Y cells (DA-Like cells) and treated with 1-Methyl-4-phenylpyridinium iodide to stimulate Reactive oxidative species (ROS) production. A transwell assay was conducted to validate the effect of hNTSCs on the Hippo pathway. We generated an MPTP-induced PD mouse model and transplanted hNTSCs into the substantia nigra of PD mice via stereotaxic surgery. After five weeks of behavioral testing, the brain samples were validated by immunoblotting and immunostaining to confirm the niche control of hNTSCs. RESULTS: In-vitro experiments showed that hNTSCs significantly increased cell survival and exerted anti-inflammatory effects by controlling ROS-mediated ER stress and hippocampal signaling pathway factors. Similarly, the in-vivo experiments demonstrated an increase in anti-inflammatory effects and cell survival rate. After transplantation of hNTSCs, the PD mouse model showed improved mobility and relief from PD symptoms. CONCLUSION: hNTSCs improved the survival rate of dopaminergic neurons by manipulating the hippocampal pathway through Yes-associated protein (YAP)/transcriptional coactivator with a PDZ-binding motif (TAZ) by reducing inflammatory cytokines. In this study, we found that controlling the niche of hNTSCs had a therapeutic effect on PD lesions.

A versatile approach to Ullmann C-N couplings at room temperature: new families of nucleophiles and electrophiles for photoinduced, copper-catalyzed processes.

The use of light to facilitate copper-catalyzed cross-couplings of nitrogen nucleophiles can enable C-N bond formation to occur under unusually mild conditions. In this study, we substantially expand the scope of such processes, establishing that this approach is not limited to reactions of carbazoles with iodobenzene and alkyl halides. Specifically, we demonstrate for the first time that other nitrogen nucleophiles (e.g., common pharmacophores such as indoles, benzimidazoles, and imidazoles) as well as other electrophiles (e.g., hindered/deactivated/heterocyclic aryl iodides, an aryl bromide, an activated aryl chloride, alkenyl halides, and an alkynyl bromide) serve as suitable partners. Photoinduced C-N bond formation can be achieved at room temperature using a common procedure with an inexpensive catalyst (CuI) that does not require a ligand coadditive and is tolerant of moisture and a variety of functional groups.

Discovery of Orally Bioavailable Phthalazinone Analogues as an ENPP1 Inhibitor for STING-Mediated Cancer Immunotherapy.

A lack of the T cell-inflamed tumor microenvironment limits the efficacy of immune checkpoint inhibitors (ICIs). Activation of stimulator of interferon genes (STING)-mediated innate immunity has emerged as a novel therapeutic approach in cancer therapy. 2',3'-Cyclic GMP-AMP (cGAMP) is a natural STING agonist; however, cGAMP is subjected to endogenous degradation by ecto-nucleotide pyrophosphatase phosphodiesterase 1 (ENPP1). To improve the ICI response rate, we developed 29f, a novel ENPP1 inhibitor with phthalazin-1(2H)-one as the core scaffold. 29f inhibited the cGAMP hydrolysis by ENPP1 in vitro (IC50 = 68 nM) and enhanced the STING-mediated type I interferon response in both immune and tumor cells. 29f demonstrated excellent metabolic stability and bioavailability (F = 65%). Orally administered 29f promoted tumor growth inhibition in a CT26 syngeneic model and increased the anti-PD-L1 response. Furthermore, 29f-induced immunological memory prevented the tumor relapse against tumor rechallenge, suggesting the promising therapeutic potential of 29f.