Background: Exonuclease 1 (EXO1) has been identified to be highly expressed in different human malignancies, but its expression and prognostic role in lung adenocarcinoma (LUAD) remain unknown. Materials and Methods: Two independent cohorts extracted from public databases and one cohort from our center were analyzed in this study. Expression levels of EXO1 in LUAD tissues and paired para-cancer tissues were detected. The prognostic value of EXO1 in LUAD patients was evaluated in the three cohorts. Enrichment analyses were performed to explore the possible underlying biological pathways. Moreover, we also explored the correlations between EXO1 and tumor-infiltrating immune cells and evaluated the impact of EXO1 knock-down on the migration of lung cancer cells. Results: In this study, we found that EXO1 was highly expressed in LUAD tissues compared with para-cancerous tissues in public databases (p < 0.01), which was consistent with our data (p < 0.01). Survival analysis indicated that high expression of EXO1 was associated with poor prognosis in LUAD (p < 0.01). Enrichment analyses indicated that biological pathways like cell cycle regulation, DNA damage and repair, immune response, neuroactive ligand-receptor interaction, may be associated with EXO1 aberrant expression. Moreover, high expression of EXO1 was correlated with decreased infiltrating B cells (p < 0.01) and CD4+ T cells (p < 0.01) levels, and low infiltrating levels of B cells (p < 0.01) and dendritic cells (DCs) (p < 0.05) indicated poor overall survival (OS) in LUAD. Additionally, in vitro experiments suggested that knockdown of EXO1 may inhibit the migratory ability of lung cancer cells. Conclusion: In conclusion, EXO1 is a potential prognostic biomarker in LUAD, and correlates with infiltrating levels of immune cells in the tumor microenvironment. Further prospective validation of EXO1 in lung cancer is warranted.

Phosphoserine aminotransferase 1 (PSAT1) may be an oncogene that plays an important role in various cancer types. However, there are still many gaps in the expression of PSAT1 gene and its biological impact in different types of tumors. Here, we performed an integrated pan-cancer analysis to explore the potential molecular mechanisms of PSAT1 in cancers. We found that most human tumors express higher levels of PSAT1 than normal tissues, and that higher PSAT1 expression is associated with worse prognosis in Lung adenocarcinoma (LUAD), Pan-kidney cohort (KIPAN) and breast invasive carcinoma (BRCA), etc. In BRCA cases, the prognosis of patients with altered PSAT1 was worse than that of patients without alteration. In addition, PSAT1 hypermethylation is associated with T cell dysfunction and shortened survival time in BRCA. The Gene Set Enrichment Analysis (GSEA) analysis showed that PSAT1 can be enriched into the classic signaling pathways of cancer such as mTORC1 signaling, MYC targets and JAK STAT3. Further analysis demonstrated that PSAT1 was enriched in immune related signaling pathways in LUAD and BRCA. The results of immunoassay showed that PSAT1 was associated with immune cell infiltration in multiple cancer species. Furthermore, expression of PSAT1 was correlated with both tumor mutational burden (TMB) and microsatellite instability (MSI) in BRCA. Additionally, a remarkable correlation was found between PSAT1 expression and TMB in LUAD, and the expression of PSAT1 was negatively correlated with the Tumor Immune Dysfunction and Exclusion (TIDE) value, suggesting a good effect of immunotherapy. Together, these data suggest that PSAT1 expression is associated with the clinical prognosis, DNA methylation, gene mutations, and immune cell infiltration, contributing to clarify the role of PSAT1 in tumorigenesis from a variety of perspectives. What’s more, PSAT1 may be a new biomarker for survival and predicting the efficacy of immunotherapy for LUAD and BRCA.

Background: Aerobic glycolysis plays a key role in tumor metabolic reprogramming to reshape the immune microenvironment. The phosphoglycerate kinase 1 (PGK1) gene codes a glycolytic enzyme that converts 1,3-diphosphoglycerate to 3-phosphoglycerate. However, in lung adenocarcinoma (LUAD), the role of PGK1 in altering the tumor microenvironment (TME) has not yet been determined. Methods: Raw data, including bulk DNA and mRNA-seq data, methylation modification data, single-cell RNA-seq data, proteomics data, clinical case characteristics survival, immunotherapy data, and so on, were obtained from multiple independent public data sets. These data were reanalyzed to uncover the prognosis and immunological characteristics of PGK1 in LUAD. Results: We found that PGK1 mRNA and protein were considerably over-expressed in LUAD compared to normal tissue and that high PGK1 expression is associated with poorer prognostic outcomes in LUAD. The enrichment analysis of PGK1 co-expressed genes in lung adenocarcinoma revealed that PGK1 may be involved in hypoxia, metabolism, DNA synthesis, cell cycle, PI3K/AKT, and various immune and inflammatory signaling pathways. Furthermore, PGK1 is also linked to the recruitment of numerous immune cells, including aDC (dendritic cells), macrophages, and neutrophils. More importantly, PGK1 was highly expressed in immunosuppressive cells, including M2 macrophages, Tregs, and exhausted T cells, among others. Finally, higher PGK1 expression indicated significant correlations to immune checkpoints, TMB (tumor mutation burden), and high response to immunotherapy. Conclusions: The presented findings imply that PGK1, as a glycolysis core gene, may be important for the modification of the immune microenvironment by interacting with the tumor metabolism. The results of this study provide clues for a potential immunometabolic combination therapy strategy in LUAD, for which more experimental and clinical translational research is needed.

Cardiac conduction regulatory RNA (CCRR) is down‐regulated in the pathogenesis of heart failure (HF), which accordingly suppresses cardiac conduction while promoting arrhythmogenicity. Meanwhile, CX43 was reported to play a role in the pathogenesis of metastatic breast cancer and melanoma brain colonization. In this study, we studied the role of long non‐coding RNA CCRR and its interaction with CX43 in brain metastasis of breast cancer. Breast cancer patients were grouped according to the metastasis status. Real‐time PCR and IHC assay were used to measure the expression of lncRNA‐CCRR and CX43 in patients. Western blot was conducted to observe the effect of lncRNA‐CCRR on the expression of CX43 in MDA‐MB‐231BR and BT‐474BR cells. Compared with the non‐metastasis group, the mRNA expression of tissue lncRNA‐CCRR, cerebrospinal fluid (CSF) lncRNA‐CCRR, tissue CX43 and tissue protein expression of CX43 were both evidently up‐regulated in metastasis patients, especially in patients with brain metastasis. The expression of lncRNA‐CCRR was positively correlated with the up‐regulated expression of CX43. Moreover, CX43 expression was significantly lower in MDA‐MB‐231WT cells compared with that in MDA‐MB‐231BR cells. Also, the overexpression of lncRNA‐CCRR evidently increased dye transfer rate from astrocytes to MDA‐MB‐231BR/BT‐474BR cells but reduced lncRNA‐CCRR expression and suppressed the transmigration of MDA‐MB‐231BR/BT‐474BR cells in a blood‐brain barrier (BBB) model. In this study, we demonstrated that the presence of lncRNA‐CCRR could up‐regulate the expression of CX43, which promoted gap junction formation in brain metastasis of breast cancer. Accordingly, the communication between breast cancer cells and astrocytes was also promoted.

Nucleolar and spindle-associated protein 1 (NUSAP1) is a potential molecular marker and intervention target for glioblastoma (GBM). In this study, we aim to investigate upstream regulatory lncRNAs and miRNAs of NUSAP1 through both experimental and bioinformatic methods. We screened upstream lncRNAs and miRNAs of NUSAP1 through multiple databases based on ceRNA theory. Then, in vitro and in vivo experiments were performed to elucidate the relevant biological significance and regulatory mechanism among them. Finally, the potential downstream mechanism was discussed. LINC01393 and miR-128-3p were screened as upstream regulatory molecules of NUSAP1 by TCGA and ENCORI databases. The negative correlations among them were confirmed in clinical specimens. Biochemical studies revealed that overexpression or knockdown of LINC01393 respectively enhanced or inhibited malignant phenotype of GBM cells. MiR-128-3p inhibitor reversed LINC01393 knockdown-mediated impacts on GBM cells. Then, dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to validate LINC01393/miR-128-3p/NUSAP1 interactions. In vivo, LINC01393-knockdown decreased tumor growth and improved mice survival, while restoration of NUSAP1 partially reversed these effects. Additionally, enrichment analysis and western blot revealed that the roles of LINC01393 and NUSAP1 in GBM progression were associated with NF-κB activation. Our findings showed that LINC01393 sponged miR-128-3p to upregulate NUSAP1, thereby promoting GBM development and progression via activating NF-κB pathway. This work deepens understanding of GBM mechanisms and provides potential novel therapeutic targets for GBM.

Brain metastases (BMs) of lung cancer are common malignant intracranial tumours associated with severe neurological symptoms and an abysmal prognosis. Prostate-specific membrane antigen (PSMA) has been reported to express significantly in a variety of solid tumours. However, the clinical applications of ⁶⁸Ga-PSMA PET/CT and the mechanism of PSMA expression in patients with BMs of lung cancer have rarely been reported. Experiments with ⁶⁸Ga-PSMA PET/CT and immunohistochemical staining were conducted to evaluate the expression of PSMA from seven patients with BMs of lung cancer who accepted surgical treatment in Fudan University Shanghai Cancer Center between October 2020 and October 2021. The mechanism of PSMA expression in BMs of lung cancer was explored by using single-cell RNA sequencing. The median maximum standardized uptake value (SUVmax) in BMs was higher than that in primary lung cancer (8.6 ± 2.8 vs. 3.6 ± 1.3, P < 0.01). The mean SUVmax in BMs was 1.76-fold higher than that in the liver, which indicated the potential of PSMA radioligand therapy (PSMA-RLT) for BMs. BMs showed intense PSMA staining, while normal lung tissue had no PSMA staining and there was only faint primary lung cancer staining by immunohistochemistry (IHC). Single-cell RNA sequencing (scRNA-seq) analysis found that PSMA was mainly expressed in oligodendrocytes of BMs, whereas it was expressed at lower levels in solid cells of lung cancer. PSMA expression in oligodendrocytes might be regulated by the factors ATF3 and NR4A1, which were associated with ER stress.