Molecular mechanism of radiation tolerance in lung adenocarcinoma cells using single-cell RNA sequencing.

The efficacy of radiotherapy, a cornerstone in the treatment of lung adenocarcinoma (LUAD), is profoundly undermined by radiotolerance. This resistance not only poses a significant clinical challenge but also compromises patient survival rates. Therefore, it is important to explore this mechanism for the treatment of LUAD. Multiple public databases were used for single-cell RNA sequencing (scRNA-seq) data. We filtered, normalized and downscaled scRNA-seq data based on the Seurat package to obtain different cell subpopulations. Subsequently, the ssGSEA algorithm was used to assess the enrichment scores of the different cell subpopulations, and thus screen the cell subpopulations that are most relevant to radiotherapy tolerance based on the Pearson method. Finally, pseudotime analysis was performed, and a preliminary exploration of gene mutations in different cell subpopulations was performed. We identified HIST1H1D+ A549 and PIF1+ A549 as the cell subpopulations related to radiotolerance. The expression levels of cell cycle-related genes and pathway enrichment scores of these two cell subpopulations increased gradually with the extension of radiation treatment time. Finally, we found that the proportion of TP53 mutations in patients who had received radiotherapy was significantly higher than that in patients who had not received radiotherapy. We identified two cellular subpopulations associated with radiotherapy tolerance, which may shed light on the molecular mechanisms of radiotherapy tolerance in LUAD and provide new clinical perspectives.

A Study on the Clinical Significance of Blood Exosomal PD-L1 in Non-Small Cell Lung Cancer Patients and its Correlation with PD-L1 in Tumor Tissues.

Exosomal programmed cell-death ligand 1 (ePD-L1) can influence immune inhibition and dysfunction. We were dedicated to unearthing the relation between ePD-L1 in blood and pathological characteristics as well as PD-L1 in tumor tissues. We recruited 65 non-small cell lung cancer (NSCLC) patients for exosome extraction and detected the blood ePD-L1 expression in these patients by enzyme-linked immunosorbent assay (ELISA) method. Besides, the correlation between blood ePD-L1 and patients' pathological characteristics was also analyzed. The expression of PD-L1 in tumor tissues was tested by immunohistochemistry (IHC) and its correlation with blood ePD-L1 expression level was analyzed by Spearman correlation coefficient. No significant correlation was observed in PD-L1 expression levels between blood-derived exosome and tumor tissue. Altogether, high blood ePD-L1 expression was relevant to NSCLC progression, while no such relevance to PD-L1 expression in tumor tissue.

Hsa_circ_0017639 regulates cisplatin resistance and tumor growth via acting as a miR-1296-5p molecular sponge and modulating sine oculis homeobox 1 expression in non-small cell lung cancer.

Cisplatin (DDP)-induced chemoresistance is an important reason for the failure of non-small cell lung cancer (NSCLC) treatment. Circular RNAs (circRNAs) participate in the chemoresistance of diverse cancers. However, the function of hsa_circ_0017639 (circ_0017639) in the DDP resistance of NSCLC is unclear. Forty-one NSCLC samples (21 DDP-resistant samples and 20 DDP-sensitive samples) were utilized in the research. The relative expression levels of some genes were determined by real-time quantitative polymerase chain reaction (RT-qPCR). 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay for half-maximal inhibitory concentration (IC50) value of DDP and cell viability, colony formation and 5-ethynyl-2'-deoxyuridine (EDU) assays for cell proliferation, flow cytometry assay for cell apoptosis, transwell assay for cell invasion and wound-healing assay for cell migration were performed. The regulation mechanism of circ_0017639 was demonstrated by a dual-luciferase reporter assay. We observed higher levels of circ_0017639 in DDP-resistant NSCLC samples and cells. Functionally, circ_0017639 silencing decreased tumor growth and elevated DDP sensitivity in vivo and induced apoptosis, repressed proliferation, invasion, and migration of DDP-resistant NSCLC cells in vitro. Mechanically, circ_0017639 modulated sine oculis homeobox 1 (SIX1) expression via sponging microRNA (miR)-1296-5p. Also, miR-1296-5p inhibitor restored circ_0017639 knockdown-mediated impacts on cell DDP resistance in DDP-resistant NSCLCs. Furthermore, SIX1 overexpression counteracted the inhibiting impact of miR-1296-5p upregulation on DDP resistance and malignant phenotypes of DDP-resistant NSCLC cells. In conclusion, circ_0017639 conferred DDP resistance and promoted tumor growth via elevating SIX1 expression through sequestering miR-1296-5p in NSCLC, providing a new mechanism for understanding the chemoresistance and progression of NSCLC.

EP300 as an oncogene correlates with poor prognosis in esophageal squamous carcinoma.

E1A Binding Protein P300 (EP300) is one of the mutations of genes involved in histone modifications in esophageal squamous cell carcinoma (ESCC). However, its clinical relevance, potential function and mechanisms have remained elusive. Methods: Genomic sequencing datas from 325 esophageal squamous cell carcinoma (ESCC) cases were integrated and screened a series of frequently mutated histone modifier genes. EP300 was selected to further analyze its clinical significance, function and RNA-sequencing was performed to explore its potential mechanism. Results: Of 35 histone modifier genes, EP300 was not only a significantly mutated gene but also a frequently mutated gene with a mutation frequency of more than 10% in ESCC. EP300 mutation was associated with tumor grade, pathological T stage and lymph node metastasis, predicting a shorter cumulative survival status. Immunohistochemical analysis showed that EP300 expression was significantly higher in ESCC tumor tissues, and the expression levels were associated with poor survival of ESCC patients. Moreover, we found that EP300 knockdown led to inhibition of cell proliferation, colony formation, migration and invasion. RNA-sequencing showed EP300 knockdown led to a significant change of genes expression associated with angiogenesis, hypoxia and epithelial-to-mesenchymal transition (EMT). Conclusions: Taken together, our study identified a novel role and mechanism of EP300 in ESCC and provided epigenetic therapeutic strategies for the treatment of ESCC.