Dexamethasone improves thymoma-associated myasthenia gravis via the AKT-mTOR pathway.

Clinically, thymoma patients are often complicated with myasthenia gravis (MG). Dexamethasone, a glucocorticoid with anti-inflammatory effects, could be used as an immunosuppressant for thymoma-associated MG, but the mechanism of action remains to be explored. In this study, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, weighted gene co-expression network analysis (WGCNA) of potential targets was performed by screening the intersection targets of dexamethasone and thymoma-associated MG from the database. Furthermore, the key targets and core active components were identified by topological analysis of the protein-protein interaction (PPI) network. Molecular docking technology was applied to screen the complexes with stable binding of dexamethasone and core targets. Patients with thymoma were divided into two groups according to whether they received dexamethasone before operation, and immunohistochemistry and western blot were used to verify the selected target of dexamethasone in treating thymoma-associated MG. The results showed that the action pathway of dexamethasone on the disease was closely enriched to phosphatidylinositol 3-kinase (PI3K)-protein kinase B (PKB/AKT), mammalian target of rapamycin (mTOR) signaling pathways. The expressions of AKT1 and its downstream molecule mTOR in the thymoma microenvironment of thymoma-associated MG patients who did not receive dexamethasone before operation were higher than those in the group receiving dexamethasone before operation. This study demonstrates that dexamethasone can promote apoptosis through the AKT-mTOR pathway for the treatment of thymoma-associated MG, as validated by network pharmacology predictions and clinical specimen experiments, and can be verified by large-scale clinical trials in the future. This study also provides theoretical support and new research perspectives for this disease.

The Diagnostic and Prognostic Value of the Immune Checkpoint BGN in Thymoma.

Thymoma is frequently correlated with various autoimmune diseases. However, unequivocal therapeutic targets for thymoma remain undefined, and the role of immune checkpoints in the development of thymoma-related autoimmune illnesses is unclear. We examined 39 thymoma samples and 44 normal control samples from the GEO database. Following batch correction, we identified 224 Differentially Expressed Genes (DEGs) using the Limma package. We employed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to enrich for functional pathways of DEGs. We utilized a Protein-Protein Interaction (PPI) network to identify hub genes and determine their correlation with immune cell infiltration using CIBERSORT. Real-time quantitative polymerase chain reaction (RT-qPCR), western blot, and immunohistochemical staining were implemented to verify identified hub genes in vivo. Simultaneously, we evaluated the prognostic relevance of the hub gene using clinical data. We determined COL1A1, COL1A2, and BGN to be the central hub genes in thymoma. Validation via RT-qPCR, Western blot, and immunohistochemical staining established significant statistical divergence between thymoma tissue and the normal thymus for only BGN. Expression levels of BGN showed strong negative correlation with the infiltration level of B cells and CD4+ T cells, yet a significant positive correlation with the level of neutrophil infiltration. We found high immune infiltration levels of macrophages, NK cells, and Th1 cells in the thymoma microenvironment in patients with a high expression of BGN. Co-localization of BGN and macrophages within thymoma tissue was discerned via tissue staining. Clinical data dictated that thymoma patients exhibiting elevated BGN expression underwent longer hospital stays, longer lengths in intensive care units, greater hospitalization costs, and extended ventilator usage; our study, augmented by clinical information, recognized BGN as possessive of diagnostic and prognostic significance in thymoma through in silico and molecular verification experiments. Our findings offered an important objective for thymoma-treated autoimmune disease comprehension, supplemented by the strong association with immune infiltration.

Identification and Validation of a Prognostic Immune-Related Gene Signature in Esophageal Squamous Cell Carcinoma.

Esophageal carcinoma (EC) is a common malignant cancer worldwide. Esophageal squamous cell carcinoma (ESCC), the main type of EC, is difficult to treat because of the widespread morbidity, high fatality rates, and low quality of life caused by postoperative complications and no specific molecular target. In this study, we screened genes to establish a prognostic model for ESCC. The transcriptome expression profiles of 81 ESCC tissues and 340 normal esophageal mucosal epithelium tissues were obtained from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) cohorts. The transcriptome expression datasets of 19 esophageal squamous carcinoma cell lines were downloaded from Cancer Cell Line Encyclopedia (CCLE). The R software Limma package was used to identify 6,231 differentially expressed genes and 647 differentially expressed immune-related genes between normal and ESCC tissues. Gene functional analysis was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Weighted gene co-expression network analysis (WGCNA) was used to screen out 18 immune-related prognostic genes. We then established the prognostic and risk signature using these genes, and the patients were divided into low-risk and high-risk groups. Compared with high-risk group patients, the low-risk group patients had longer overall survival. M1 macrophages and resting dendritic cells were differentially distributed between the low-risk and high-risk groups and were related to patient survival. We also examined the functional immune cell and immune molecule levels in low-risk and high-risk group patients, with significant differences in the tumor microenvironment between the two groups. To further verify the accuracy of the prognostic risk model, we performed area under the ROC curve (AUC) analysis. The AUC value was 0.931 for the prognostic risk, which was better than the microsatellite instability (MSI) and Tumor Immune Dysfunction and Exclusion (TIDE) scores. In conclusion, we found 18 immune-related prognostic genes related to the occurrence of ESCC and established a prognostic model for predicting disease severity.

Two types of immune infiltrating cells and six hub genes can predict the occurrence of myasthenia gravis in patients with thymoma.

Thymoma is the most common primary mass in anterior mediastinum. Although associated with low malignancy, it is often accompanied by myasthenia gravis resulting in poor prognosis. Due to the dual factors of tumor immune tolerance and autoimmune reaction, it is urgent to understand the immune status of MG with thymoma. In this study, RNA sequencing data were obtained from the TCGA and GEO cohorts to identify differentially expressed messenger RNAs and infiltrated immune cells. A total of 121 samples in TCGA and 43 samples in GEO were screened out. The infiltrated immune cells were identified by CIBERSORT, in which Tfh cells and activated DC cells were abnormal in thymoma patients. The differently expressed genes were performed by package LIMMA. The functional characteristics of differently expression genes were analyzed by GO and KEGG; one GO and seven KEGG pathways were both found in both TCGA and GEO cohorts. Meanwhile, 27 common differently expressed genes were obtained and were displayed by a Venn diagram. The TRRUST was used to screen the hub genes for the common 27 different genes and 6 genes were found. Then, PPI networks were constructed. Subsequently, the relationship between SCNAs of common genes and related immune cells tested by TIMER. Kaplan-Meier plots, ROC curve and Cox's expression model for immune infiltration and hub genes were also tested. In conclusion, we found that two types of immune infiltrated cells and six hub genes can predict the occurrence of myasthenia gravis in thymoma patients.

High expression of KITLG is a new hallmark activating the MAPK pathway in type A and AB thymoma.

BACKGROUND: KIT proto-oncogene ligand (KITLG) is a pleiotropic factor which is found in diverse cancers and is involved in cell proliferation, differentiation, and survival. However, the value of KITLG in thymoma remains unclear. METHODS: A total of 121 thymoma samples from The Cancer Genome Atlas Thymoma (TCGA-THYM) dataset were used to analyze KITLG related genome-wide expression profiles, and microRNA profiles and methylation alterations and a GEO dataset-GSE29695, including 37 samples was used as verification. For cell-based studies, specific small interfering RNA targeting KITLG or a KITLG overexpression vector were used to clarify the changes of the MAPK pathway in an AB thymoma cell line Thy0517. RESULTS: Both datasets showed that high expression of KITLG was significantly associated with type A and AB thymoma. Through multiomic analysis of the TCGA-THYM, it was found that with the high expression of KITLG, there were 220 upregulated and 72 downregulated genes at the mRNA level, 79 positive and 78 negative miRNAs, 28 hypermethylation and 163 hypomethylation regions. In the thymoma cell line Thy0517, it was found that the expression of GRB2 and the phosphorylation levels of BRAF, MEK1/2, and ERK1/2 in the MAPK pathway were positively correlated with the change in KITLG. CONCLUSIONS: High expression of KITLG is a new hallmark of WHO type A and AB thymomas in which it might play a critical role through the activation of the MAPK signaling pathway. Additionally, it is hoped that KITLG will become a potential target for the diagnosis of type A and AB thymoma through further research in the future. KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: KIT proto-oncogene ligand (KITLG) is a new hallmark of type A and AB thymomas which induce a series of aberrant alteration of mRNA, miRNA and DNA methylation. The expression of KITLG is significantly higher in type A and AB than other subtypes of thymoma. WHAT THIS STUDY ADDS: KITLG activated the MAPK signaling pathway to promote type A and AB thymoma which might be a potential diagnostic biomarker or target.

Malignant solitary fibrous tumor occurring in the mediastinal pleura showing NAB2ex4-STAT6ex2 fusion and negative STAT6 immunohistochemistry: A case report.

Solitary fibrous tumor (SFT) is a rare clinical tumor, defined as a mesenchymal tumor of fibroblastic origin. A classic SFT is benign in most cases, but its clinical behavior is unpredictable. Lately, molecular analyses has discovered that almost all SFTs harbor an NAB2-STAT6 fusion gene, which is considered specific to this tumor type. Recent studies have suggested that nuclear STAT6 immunoreactivity is a highly sensitive and specific marker of SFTs and can be helpful when diagnosis is inconclusive by conventional methods. We herein report the case of a rare malignant solitary fibrous tumor occurring in the mediastinal pleura. An 82-year-old Chinese man with intermittent breathlessness was referred to our hospital. Chest CT showed a significantly enhanced irregular huge soft tissue mass in the anterior mediastinal area. After radical resection, the immunohistochemistry staining results of the sample showed that STAT6 was negative. The final diagnosis was confirmed by qualitative endpoint reverse transcriptase-polymerase chain reaction technique, showing positive NAB2ex4-STAT6ex2 fusion.