A pyroptosis-related gene signature predicts prognosis and immune microenvironment in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is a highly malignant tumor with a very poor prognosis. Pyroptosis is an inflammatory form of cell death and plays an important role in cancer development. The prognostic value of pyroptosis-related genes (PRGs) in HCC has not been studied extensively. METHODS: Unsupervised consensus clustering analysis was performed to identify two subtypes based on the expression profiles of prognostic PRGs in the The Cancer Genome Atlas (TCGA) database, and the differences between the two subtypes were compared. A prognostic model based on four PRGs was established by further least absolute shrinkage and selection operator (LASSO) Cox regression analysis and multivariate Cox regression analysis. RESULTS: Two subtypes (clusters 1 and 2) were identified by consensus clustering based on prognostic PRGs in HCC. Survival outcomes, biological function, genomic alterations, immune cell infiltration, and immune checkpoint genes were compared between the subtypes. Cluster 2 had a worse survival outcome than cluster 1. Cluster 2 was enriched for hallmarks of cancer progression, TP53 mutation, tumor-promoting immune cells, and immune checkpoint genes, which may contribute to the poor prognosis. A prognostic risk signature that predicted the overall survival (OS) of patients was constructed and validated. Consequently, a risk score was calculated for each patient. Combined with the clinical characteristics, the risk score was found to be an independent prognostic factor for survival of HCC patients. Further analysis revealed that the risk score was closely associated with the levels of immune cell infiltration and the expression profiles of immune checkpoint genes. CONCLUSIONS: Collectively, our study established a prognostic risk signature for HCC and revealed a significant correlation between pyroptosis and the HCC immune microenvironment.

Sirtuin4 impacts mitochondrial homeostasis in pancreatic cancer cells by reducing the stability of AlkB homolog 1 via deacetylation of the HRD1-SEL1L complex.

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with a poor prognosis. As a tumor inhibitor, the specific tumor suppressor mechanism of Sirtuin4(SIRT4) in PDAC remains elusive. In this study, SIRT4 was found to inhibit PDAC by impacting mitochondrial homeostasis. SIRT4 deacetylated lysine 547 of SEL1L and increased the protein level of an E3 ubiquitin ligase HRD1. As a central member of ER-associated protein degradation (ERAD), HRD1-SEL1L complex is recently reported to regulate the mitochondria, though the mechanism is not fully delineated. Here, we found the increase in SEL1L-HRD1 complex decreased the stability of a mitochondrial protein, ALKBH1. Downregulation of ALKBH1 subsequently blocked the transcription of mitochondrial DNA-coded genes, and resulted in mitochondrial damage. Lastly, a putative SIRT4 stimulator, Entinostat, was identified, which upregulated the expression of SIRT4 and effectively inhibited pancreatic cancer in vivo and in vitro.

Scaffold-based three-dimensional cell model of pancreatic cancer is more suitable than scaffold-free three-dimensional cell model of pancreatic cancer for drug discovery.

Pancreatic cancer is one of the deadliest malignancies. Three-dimensional (3D) pancreatic cancer cell models for drug screening have been established to improve treatment for pancreatic cancer. However, few studies focus on different drug responses and drug-related molecular mechanisms in various types of 3D cell models. In this study, we constructed 3D scaffold-free cell models and 3D scaffold-based cell models of pancreatic cancer, evaluated chemotherapeutic drug responses in different 3D models, assessed clinical relevance of the models, and investigated molecular mechanisms of chemoresistance and drug pathways in different 3D models. Both types of 3D models showed resistance to chemotherapeutic drugs, and scaffold-based pancreatic cancer models could better reflect in vivo drug efficacy than 2D and scaffold-free pancreatic cancer models did. Increased cell adhesion, extracellular matrix (ECM) synthesis and drug transport were essential for drug resistance in 3D models, and anti-apoptosis might contribute to extreme chemoresistance in scaffold-free models. Moreover, scaffold-based pancreatic cancer models were more suitable than scaffold-free models for drug pathway research.

BxPC-3-Derived Small Extracellular Vesicles Induce FOXP3+ Treg through ATM-AMPK-Sirtuins-Mediated FOXOs Nuclear Translocations.

Immunotherapy in pancreatic ductal adenocarcinoma (PDAC) treatment faces serious challenges, due particularly to the poor immunogenicity. Cancer cell-derived small extracellular vesicles (sEVs) play important roles in damaging the immune system. However, the effects of pancreatic cancer-derived sEVs on T lymphocytes are unknown. Here we investigated changes in phenotypes and signal transduction pathways in sEVs-treated T lymphocytes. We identified the overexpression of immune checkpoint proteins PD-1, PD-L1, CTLA4, and Tim-3 and the enrichment of FOXP3+ Treg cluster in sEVs-treated T lymphocytes by CyTOF. Gene set enrichment analysis revealed that DNA damage response and metabolic pathways might be involved in sEVs-induced Tregs. ATM, AMPK, SIRT1, SIRT2, and SIRT6 were activated sequentially in sEVs-treated T lymphocytes and essential for sEVs-upregulated expressions of FOXO1A, FOXO3A, and FOXP3. Our study reveals the impact and mechanism of pancreatic cancer cell-derived sEVs on T lymphocytes and may provide insights into developing immunotherapy strategies for PDAC treatment.

The Role of Exosomal microRNAs and Oxidative Stress in Neurodegenerative Diseases.

Neurodegenerative diseases including Alzheimer's disease and Parkinson's disease are aging-associated diseases with irreversible damage of brain tissue. Oxidative stress is commonly detected in neurodegenerative diseases and related to neuronal injury and pathological progress. Exosome, one of the extracellular vesicles, is demonstrated to carry microRNAs (miRNAs) and build up a cell-cell communication in neurons. Recent research has found that exosomal miRNAs regulate the activity of multiple physiological pathways, including the oxidative stress response, in neurodegenerative diseases. Here, we review the role of exosomal miRNAs and oxidative stress in neurodegenerative diseases. Firstly, we explore the relationship between oxidative stress and neurodegenerative diseases. Secondly, we introduce the characteristics of exosomes and roles of exosome-related miRNAs. Thirdly, we summarized the crosstalk between exosomal miRNAs and oxidative stress in neurodegenerative diseases. Fourthly, we discuss the potential of exosomes to be a biomarker in neurodegenerative diseases. Finally, we summarize the advantages of exosome-based delivery and present situation of research on exosome-based delivery of therapeutic miRNA. Our work is aimed at probing and reinforcing the recognition of the pathomechanism of neurodegenerative diseases and providing the basis for novel strategies of clinical diagnosis and treatment.

Fisetin inhibits proliferation of pancreatic adenocarcinoma by inducing DNA damage via RFXAP/KDM4A-dependent histone H3K36 demethylation.

Pancreatic adenocarcinoma (PDAC) is an extremely malignant tumor that is associated with low survival rates. Fisetin is a natural flavonoid that shows diverse antitumor effects, including DNA damage, in various cancers. Increasing studies have demonstrated that epigenetic modifications play critical roles in DNA-damage response. However, the epigenetic regulation mechanism of fisetin in cancers is hardly studied. RFXAP is a critical transcription factor for MHC II molecules, however, its transcriptional role in PDAC is poorly understood. The anti-PDAC effect of fisetin was measured by CCK-8, flow cytometry, xenograft tumor nude mice model. DNA-damage levels were examined by immunofluorescence. Bioinformatics analysis was used to examine the expression of RFXAP and other genes involved in DNA-damage response. ChIP sequencing was used to explore the transcriptional role of RFXAP. The expression of target gene KDM4A was measured by qRT-PCR and western blots. KDM4A promoter activity was analyzed using dual-luciferase reporter assay. RFXAP overexpressing or silencing of PDAC cells was used to explore the effect of RFXAP in DNA damage induced by fisetin. We found that fisetin inhibited cell proliferation and induced DNA damage and S-phase arrest in PDAC. Expression of RFXAP and other DNA-damage response genes were upregulated by fisetin. We revealed that RFXAP expression was relatively low in PDAC and correlated with tumor stage and poor prognosis. Then we explored the transcriptional role of RFXAP and found that RFXAP targeted KDM4A, a special demethylase specific for tri- and dimethylated histone H3K36. We found that overexpression of RFXAP upregulated KDM4A and attenuated methylation of H3K36, thereby impairing DNA repair and enhancing the DNA damage induced by fisetin, while RFXAP silencing showed the opposite effect. We also found the function of fisetin in enhancing the effect of chemotherapy on pancreatic cancer cells. Our findings revealed that fisetin induced DNA damage via RFXAP/KDM4A-dependent histone H3K36 demethylation, thus causing inhibition of proliferation in PDAC.

Effects of Traditional Chinese Medicine, Dilong Injection, on Random Skin Flap Survival in Rats.

BACKGROUND: Dilong injection as a medicinal preparation extracted from earthworm in traditional Chinese medicine, is used to activate blood circulation and remove blood stasis. In this research, we aim to investigate its potential effect on random skin flap survival in rat models. MATERIALS AND METHODS: McFarlane flaps were established in 60 male Sprague-Dawley rats randomly divided into two groups: the control group and the Dilong injection group. Diong injection group was injected with the Diong injection (4 mL/kg) once a day for seven days, and the control group was given an equal volume of saline solution. After seven days, flaps were obtained and stained with Hematoxylin and Eosin. Histological examination was done to determine changes in histology such as thickness of granulation tissue, tissue edema, neutrophil infiltration, and the microvascular density (MVD). In addition, immunohistochemical detection was carried out to show vascular endothelial growth factor (VEGF) expression level. RESULTS: Compared with the control group, the Dilong group exhibited more fibroblastic proliferation, thinner neutrophil infiltration with less edema through histological examination. The MVD and the VEGF expression of flaps were significantly higher. The mean superoxide dismutase activity was evidently higher in the Dilong group than in the control group, while the mean MDA level was lower. CONCLUSIONS: According to the comparison made between the two groups for histological and immunohistochemical evaluation, the Dilong injection group has potential effects on the survival of random skin flaps in rat models.