Helicobacter pylori CagA-mediated ether lipid biosynthesis promotes ferroptosis susceptibility in gastric cancer.

Helicobacter pylori, particularly cytotoxin-associated gene A (CagA)-positive strains, plays a key role in the progression of gastric cancer (GC). Ferroptosis, associated with lethal lipid peroxidation, has emerged to play an important role in malignant and infectious diseases, but the role of CagA in ferroptosis in cancer cells has not been determined. Here, we report that CagA confers GC cells sensitivity to ferroptosis both in vitro and in vivo. Mechanistically, CagA promotes the synthesis of polyunsaturated ether phospholipids (PUFA-ePLs), which is mediated by increased expression of alkylglycerone phosphate synthase (AGPS) and 1-acylglycerol-3-phosphate O-acyltransferase 3 (AGPAT3), leading to susceptibility to ferroptosis. This susceptibility is mediated by activation of the MEK/ERK/SRF pathway. SRF is a crucial transcription factor that increases AGPS transcription by binding to the AGPS promoter region. Moreover, the results demonstrated that CagA-positive cells are more sensitive to apatinib than are CagA-negative cells, suggesting that detecting the H. pylori CagA status may aid patient stratification for treatment with apatinib.

N4-Acetylcytidine Drives Glycolysis Addiction in Gastric Cancer via NAT10/SEPT9/HIF-1α Positive Feedback Loop.

Anti-angiogenic therapy has long been considered a promising strategy for solid cancers. Intrinsic resistance to hypoxia is a major cause for the failure of anti-angiogenic therapy, but the underlying mechanism remains unclear. Here, it is revealed that N4-acetylcytidine (ac4C), a newly identified mRNA modification, enhances hypoxia tolerance in gastric cancer (GC) cells by promoting glycolysis addiction. Specifically, acetyltransferase NAT10 transcription is regulated by HIF-1α, a key transcription factor of the cellular response to hypoxia. Further, acRIP-sequencing, Ribosome profiling sequencing, RNA-sequencing, and functional studies confirm that NAT10 in turn activates the HIF-1 pathway and subsequent glucose metabolism reprogramming by mediating SEPT9 mRNA ac4C modification. The formation of the NAT10/SEPT9/HIF-1α positive feedback loop leads to excessive activation of the HIF-1 pathway and induces glycolysis addiction. Combined anti-angiogenesis and ac4C inhibition attenuate hypoxia tolerance and inhibit tumor progression in vivo. This study highlights the critical roles of ac4C in the regulation of glycolysis addiction and proposes a promising strategy to overcome resistance to anti-angiogenic therapy by combining apatinib with ac4C inhibition.

Landscape of exitrons in gastric cancer.

BACKGROUND: Exitron is a new type of non-canonical alternative splicing. Accumulating evidence implies exitron may have pathological function and contribute to another source of anti-tumor immunogenicity in various cancers. Its role in gastric cancer remains poorly understood. Large-scale, multi-omics analysis could comprehensively characterize the landscape of exitrons in gastric cancer, reveal undiscovered mechanism and hopefully identify molecular biomarkers for predicting immunotherapy response. METHODS: We collected datasets from five studies for analysis. RNA sequencing was used for exitron identification. Somatic mutations were detected by whole exome sequencing. Neopeptides were confirmed by proteome mass spectrometry. FINDINGS: 42174 gastric cancer-specific exitrons (GCSEs) were identified in 632 patients. GCSEs were clinically relevant to gender, age, Lauren type, tumor stage and prognosis. Tissue specificity test and pathogenic exitron prediction revealed their unique functional impact. GCSEs were mutually exclusive with mutations and demonstrated both unique and complementary function against TP53 mutation in gastric cancer. We further established splicing regulatory network to reveal upstream regulation of exitron splicing. We also evaluated the immunogenicity and diagnostic potential of GCSEs. Evidence of GCSEs-derived neopeptide expression was validated by whole proteome mass spectrometry. PD-1 and Siglecs were significantly increased in high neoantigen load patients. But exitron-related biomarkers failed to predict immunotherapy response, possibly due to small sample size and insufficient sequencing depth. INTERPRETATION: The present study provided a comprehensive multidimensional landscape of gastric cancer exitrons and underscores insights into underexplored mechanism in gastric cancer pathology. FUNDING: The Guangdong Provincial Key Laboratory of Precision Medicine for Gastroinstestinal Cancer (2020B121201004), the Guangdong Provincial Major Talents Project (No. 2019JC05Y361) and National Natural Science Foundation of China (grant number:82172960 and 81872013).

Visible Light-Driven Alkyne-Grafted Ethylene-Bridged Azobenzene Chromophores for Photothermal Utilization.

Molecular photoswitches are considered to be important candidates in the field of solar energy storage due to their sensitive and reversible bidirectional optical response. Nevertheless, it is still a daunting challenge to design a molecular photoswitch to improve the low solar spectrum utilization and quantum yields while achieving charging and discharging of heat without solvent assistance. Herein, a series of visible-light-driven ethylene-bridged azobenzene (b-Azo) chromophores with different alkyne substituents which can undergo isomerization reactions promoted in both directions by visible light are reported. Their visible light responsiveness improves their solar spectrum utilization while also having high quantum yields. In addition, as the compounds are liquids, there is no need to dissolve the compounds in order to exploit this switching. The photoisomerization of b-Azo can be adjusted by alkyne-related substituents, and hexyne-substituted b-Azo is able to store and release photothermal energy with a high density of 106.1 J·g-1, and can achieve a temperature increase of 1.8 °C at a low temperature of -1 °C.

One-step green synthesis of oil-dispersible carbonized polymer dots as eco-friendly lubricant additives with superior dispersibility, lubricity, and durability.

Chemical functionalization provides effective protocols for inorganic nanomaterials as oil-dispersible lubricant additives. Nevertheless, harsh reaction conditions and arduous post-processing are frequently encountered when adopting this approach. Herein, four types of carbonized polymer dots (CPDs) with admirable dispersibility and long-term stability (more than 6 months without any sediments) in polyethylene glycol (PEG200) were synthesized by a one-step and green solvothermal route using saccharides as the single precursors. The tribological behaviors of CPDs as the lubricant additives of PEG200 were systematically evaluated and compared, confirming that the anti-wear and friction-reducing performances of PEG200 can be effectively enhanced after blended with CPDs. Clarified by the friction evaluations and worn surface detections, the superior lubricity and durability of CPDs-c are mainly attributed to the synergy between the interfacial adsorption of polymeric shells, the nano-lubrication effects of carbon cores, and the establishment of CPDs-inserted tribofilm with a uniform thickness of about 86 nm. This work explores a green and facile strategy for synthesizing the CPDs toward oil lubrication and reveals the lubrication mechanism of CPDs, which facilitates the practical application of CPDs in tribology.

Fibroblast-derived LPP as a biomarker for treatment response and therapeutic target in gastric cancer.

Association of tumor microenvironment and immune checkpoint (e.g., PD-L1) is important for immune escape, impacting chemotherapy and immunotherapy efficacy. We aimed to investigate biomarkers and therapeutic targets against treatment resistance in gastric cancer. Abundances of tumor-infiltrating immune cells were estimated in multiple datasets. Three patient subgroups (A, B, and C) were identified based on seven types of PD-L1- and IFN-γ-associated immune cells. Patients yielded increased prognosis from subgroup A to C (p = 0.027). Subgroup A was characterized by high activated CD4+ memory T cell infiltration, while more resting CD4+ memory T cells were in subgroup C. Further, a risk score was developed for prognostication. Lipoma preferred partner (LPP), as the hub gene in subgroup-related regulatory network, was upregulated (p < 0.01) and was associated with high risk score (p < 0.001) and poor survival (p < 0.05). Bioinformatics analyses and experiments found that LPP expressed restrictively in fibroblasts and associated with activated CD4+ memory T cell infiltration and tumor growth. High-LPP patients yielded fewer benefits from chemotherapy or immunotherapy, compared with the low-LPP group. We finally identified 28 compounds as sensitive drugs for high-LPP patients. Our findings suggested LPP might be a biomarker for treatment response and therapeutic target in gastric cancer.

Nuclear MYH9-induced CTNNB1 transcription, targeted by staurosporin, promotes gastric cancer cell anoikis resistance and metastasis.

Rationale: Peritoneal metastasis predicts poor prognosis of gastric cancer (GC) patients, and the underlying mechanisms are poorly understood. Methods: The 2-DIGE, MALDI-TOF/TOF MS and single-cell transcriptome were used to detect differentially expressed proteins among normal gastric mucosa, primary GC and peritoneal metastatic tissues. Lentiviruses carrying shRNA and transcription activator-like effector nuclease technology were used to knock down myosin heavy chain 9 (MYH9) expression in GC cell lines. Immunofluorescence, immune transmission electron microscopy, chromatin fractionation, co-immunoprecipitation, and assays for chromatin immunoprecipitation, dual luciferase reporter, agarose-oligonucleotide pull-down, flow cytometry and cell anoikis were performed to uncover nuclear MYH9-induced ß-catenin (CTNNB1) transcription in vitro. Nude mice and conditional transgenic mice were used to investigate the findings in vivo. Results: We observed that MYH9 was upregulated in metastatic GC tissues and was associated with a poor prognosis of GC patients. Mechanistically, we confirmed that MYH9 was mainly localized in the GC cell nuclei by four potential nuclear localization signals. Nuclear MYH9 bound to the CTNNB1 promoter through its DNA-binding domain, and interacted with myosin light chain 9, ß-actin and RNA polymerase II to promote CTNNB1 transcription, which conferred resistance to anoikis in GC cells in vitro and in vivo. Staurosporine reduced nuclear MYH9 S1943 phosphorylation to inhibit CTNNB1 transcription, Wnt/ß-catenin signaling activation and GC progression in both orthotropic xenograft GC nude mouse and transgenic GC mouse models. Conclusion: This study identified that nuclear MYH9-induced CTNNB1 expression promotes GC metastasis, which could be inhibited by staurosporine, indicating a novel therapy for GC peritoneal metastasis.

Erratum: MicroRNA-647 targets SRF-MYH9 axis to suppress invasion and metastasis of gastric cancer: Erratum.

[This corrects the article DOI: 10.7150/thno.20512.].

Diagnostic accuracy of BRCA1-associated protein 1 in malignant mesothelioma: a meta-analysis.

BACKGROUND: Conventional measurements are not always helpful in the diagnosis of malignant mesothelioma (MM). Increasing studies indicate that loss of BRCA1-associated protein 1 (BAP1) detected by immunohistochemistry (IHC) is a useful diagnostic marker for MM. In this meta-analysis, we investigated the diagnostic accuracy of BAP1 in MM. RESULTS: In total, 12 eligible studies with a total of 1824 patients were selected. Results indicated that loss of BAP1 sustained a pooled sensitivity of 0.56 (95% CI, 0.50-0.62), specificity of 1.00 (95% CI, 0.95-1.00), PLR of 548.82 (95% CI, 11.31-2.7 × 104), NLR of 0.44 (95% CI, 0.39-0.50), DOR of 1247.78 (95% CI, 25.08 -6.2 × 104) in discriminating MM from non-MM. The AUC of 0.72, reflecting the SROC, indicated moderate diagnostic accuracy. Subgroup analysis showed that BAP1 detection in histological specimens owned the higher diagnostic performance than cytological ones. In addition, BAP1 showed superior diagnostic accuracy in epithelioid MM than biphasic or sarcomatoid MM. MATERIALS AND METHODS: PubMed, Embase and the Cochrane Library and reference lists of related articles were searched, and studies that evaluated the utility of BAP1 in MM were included. Data from eligible studies were pooled to estimate sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR). Summary receiver operating curves (SROC) was applied to estimate overall diagnostic accuracy. CONCLUSIONS: Current meta-analysis indicates that detection of BAP1 by IHC is a useful diagnostic marker for MM. Loss of BAP1 almost provides confirming diagnosis for MM, while positive staining for BAP1 is not enough to exclude non-MM.

MicroRNA-647 Targets SRF-MYH9 Axis to Suppress Invasion and Metastasis of Gastric Cancer.

MicroRNAs (miRNAs) play important roles in regulating tumour development and progression. Here we show that miR-647 is repressed in gastric cancer (GC), and associated with GC metastasis. Moreover, we identify that miR-647 can suppress GC cell migration and invasion in vitro. Mechanistically, we confirm miR-647 directly binds to the 3' untranslated regions of SRF mRNA, and SRF binds to the CArG box located at the MYH9 promoter. CCG-1423, an inhibitor of RhoA/SRF-mediated gene transcription, inhibits the expression of MYH9, especially in SRF downregulated cells. Overexpression of miR-647 inhibits MGC 80-3 cells' metastasis in orthotropic GC models, but increasing SRF expression in these cells reverses this change. Importantly, we found the synergistic inhibition effect of CCG-1423 and agomir-647, an engineered miRNA mimic, on cancer metastasis in orthotropic GC models. Our study demonstrates that miR-647 functions as a tumor metastasis suppressor in GC by targeting SRF/MYH9 axis.

MerTK Does Not Mediate Phagocytosis of Staphylococcus aureus but Attenuates Inflammation Induced by Staphylococcal Lipoteichoic Acid Through Blocking NF-κB Activation.

Mer receptor tyrosine kinase (MerTK) expressed in macrophages is essential for phagocytosis of apoptotic cells. Here, we investigate whether MerTK is involved in the phagocytosis of Staphylococcus aureus (S. aureus) and regulation of staphylococcal lipoteichoic acid (LTA)-induced inflammatory response in macrophages. We found that stimulating RAW264.7 macrophages with S. aureus activated multiple signaling pathways including toll-like receptor 2 (TLR2), scavenger receptor A (SR-A), and MerTK. Meanwhile, S. aureus stimulation also induced activation of proteins focal adhesion kinase (FAK) and Rac1, which are related to phagocytosis. Pretreatment with a specific Mer-blocking antibody significantly inhibited S. aureus-induced phosphorylation of MerTK, while it had no effect on S. aureus-induced activation of FAK and Rac1. Moreover, by confocal laser microscope, we observed that the antibody blockade of MerTK had little impact on the phagocytosis of S. aureus by RAW264.7 macrophages. Additionally, pretreatment with this antibody further promoted LTA-induced phosphorylation of nuclear factor κB (NF-κB) p65 subunit and production of pro-inflammatory cytokines, such as TNF-α, IL-6, IL-1ß, and macrophage inflammatory protein-2 (MIP-2). Collectively, these results suggest that MerTK does not play an essential role in the phagocytosis of S. aureus but attenuates inflammation induced by staphylococcal LTA through blocking NF-κB activation.

Establishment and evaluation of four different types of patient-derived xenograft models.

BACKGROUND: Patient-derived xenografts (PDX) have a biologically stable in tumor architecture, drug responsiveness, mutational status and global gene-expression patterns. Numerous PDX models have been established to date, however their thorough characterization regarding the tumor formation and rates of tumor growth in the established models remains a challenging task. Our study aimed to provide more detailed information for establishing the PDX models successfully and effectively. METHODS: We transplanted four different types of solid tumors from 108 Chinese patients, including 21 glioblastoma (GBM), 11 lung cancers (LC), 54 gastric cancers (GC) and 21 colorectal cancers (CRC), and took tumor tissues passaged for three successive generations. Here we report the rate of tumor formation, tumor-forming times, tumor growth curves and mortality of mice in PDX model. We also report H&E staining and immunohistochemistry for HLA-A, CD45, Ki67, GFAP, and CEA protein expression between patient cancer tissues and PDX models. RESULTS: Tumor formation rate increased significantly in subsequent tumor generations. Also, the survival rates of GC and CRC were remarkably higher than GBM and LC. As for the time required for the formation of tumors, which reflects the tumor growth rate, indicated that tumor growth rate always increased as the generation number increased. The tumor growth curves also illustrate this law. Similarly, the survival rate of PDX mice gradually improved with the increased generation number in GC and CRC. And generally, there was more proliferation (Ki67+) in the PDX models than in the patient tumors, which was in accordance with the results of tumor growth rate. The histological findings confirm similar histological architecture and degrees of differentiation between patient cancer tissues and PDX models with statistical analysis by GraphPad Prism 5.0. CONCLUSION: We established four different types of PDX models successfully, and our results add to the current understanding of the establishment of PDX models and may contribute to the extension of application of different types of PDX models.

[TALEN-mediated MYH9 Knock-down and its influence on cell cycle and apoptosis of MGC803 cell line].

OBJECTIVE: To construct a MYH9 gene knockout model in MGC803 cell line using transcription activator-like effector nuclease (TALEN) and observe its effect on cell cycle and apoptosis. METHODS: According to FastTALE(TM) TALEN Kit, we designed TALEN pairs and constructed the plasmids targeting to MYH9 gene. After detecting their activity in MGC803 cells by plasmid transfection, DNA sequencing, RT-PCR and western blot, we selected the monoclonal cells and studied the changes in the cell cycle and apoptosis. RESULTS: MYH9 gene could not be knocked out but knocked down in selected MGC803 monoclonal cells, which caused cell cycle arrested at G2/M phase (P<0.05) and a significant increase in the cell number with early apoptosis (P<0.01). CONCLUSION: We successfully generated a MYH9 knockdown model in MGC803 cell lines by TALEN, which could be in favor of MYH9 function study in gastric cancer.