RPL9 acts as an oncogene by shuttling miRNAs through exosomes in human hepatocellular carcinoma cells.

The exosomal pathway is an essential mechanism that regulates the abnormal content of microRNAs (miRNAs) in hepatocellular carcinoma (HCC). The directional transport of miRNAs requires the assistance of RNA­binding proteins (RBPs). The present study found that RBPs participate in the regulation of miRNA content through the exosomal pathway in HCC cells. First, differential protein expression profiles in the serum exosomes of patients with HCC and benign liver disease were detected using mass spectrometry. The results revealed that ribosomal protein L9 (RPL9) was highly expressed in serum exosomes of patients with HCC. In addition, the downregulation of RPL9 markedly suppressed the proliferation, migration and invasion of HCC cells and reduced the biological activity of HCC­derived exosomes. In addition, using miRNA microarrays, the changes in exosomal miRNA profiles in HCC cells caused by RPL9 knockdown were examined. miR­24­3p and miR­185­5p were most differentially expressed, as verified by reverse transcription­quantitative PCR. Additionally, using RNA immunoprecipitation, it was found that RPL9 was directly bound to the two miRNAs and immunofluorescence assays confirmed that RPL9 was able to carry miRNAs into recipient cells via exosomes. Overexpression of miR­24­3p in cells increased the accumulation of miR­24­3p in exosomes and simultaneously upregulated RPL9. Excessive expression of miR­24­3p in exosomes also increased their bioactivity. Exosome­mediated miRNA regulation and transfer require the involvement of RBPs. RPL9 functions as an oncogene, can directly bind to specific miRNAs and can be co­transported to receptor cells through exosomes, thereby exerting its biological functions. These findings provide a novel approach for modulating miRNA profiles in HCC.

Integrative analysis of lactylation-related genes and establishment of a novel prognostic signature for hepatocellular carcinoma.

BACKGROUND: Lactylation has been found to involve in regulating many types of biological process in cancers. However, research on lactylation-related genes in predicting the prognosis of hepatocellular carcinoma (HCC) remains limited. METHODS: The differential expression of lactylation-related genes (EP300 and HDAC1-3) in pan-cancer were examined in public databases. HCC patient tissues were obtained for mRNA expression and lactylation level detection by RT-qPCR and western blotting. Transwell migration assay, CCK-8 assay, EDU staining assay and RNA-seq were performed to verify the potential function and mechanisms in HCC cell lines after lactylation inhibitor apicidin treatment. lmmuCellAI, quantiSeq, xCell, TIMER and CIBERSOR were used to analyze the correlation between transcription levels of lactylation-related genes and immune cell infiltration in HCC. Risk model of lactylation-related genes was constructed by LASSO regression analysis, and prediction effect of the model was evaluated. RESULT: The mRNA levels of lactylation-related genes and lactylation levels were higher in HCC tissues than normal samples. The lactylation levels, cell migration, and proliferation ability of HCC cell lines were suppressed after apicidin treatment. The dysregulation of EP300 and HDAC1-3 was associated with proportion of immune cell infiltration, especially B cell. Upregulation of HDAC1 and HDAC2 was closely associated with poorer prognosis. Finally, a novel risk model, based on HDAC1 and HDAC2, was developed for prognosis prediction in HCC. CONCLUSION: HDAC1 and HDAC2 are expected to become new biomarkers for HCC. Risk scoring model based on HDAC1 and HDAC2 can be used to predict the prognosis of HCC patients.

Construction and validation of chemoresistance-associated tumor- infiltrating exhausted-like CD8+ T cell signature in breast cancer: cr-TILCD8TSig.

Background: Accumulating evidence has revealed that CD8+ T cell exhaustion (Tex) results in worse immunotherapy outcomes. However, the molecular functions and mechanisms of action of Tex in chemoresistance needed to be elucidated. Methods: The populations of tumor-infiltrating CD8+ T cells (TILCD8Ts) in chemoresistant and chemosensitive groups of the GSE25066 dataset were calculated using CIBERSORT. Differentially expressed genes (DEGs) between TILCD8Ts and other immune cells were explored by integrating 16 immune cell datasets downloaded from the gene expression omnibus (GEO) database. Gene ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, univariate and multivariate Cox regression, and least absolute shrinkage and selection operator (LASSO) regression of TILCD8T-specific upregulated genes were used to construct a chemoresistant TILCD8T signature (cr-TILCD8TSig). Clinical prognostic data, genomic alterations, chemotherapy response, and immunotherapy response were compared between the different cr-TILCD8TSig subgroups in the GSE25066 and the cancer genome atlas breast cancer (TCGA-BRCA) cohorts. Results: A cr-TILCD8TSig with exhausted features was identified, consisting of seven genes (TCF7, RARRES3, ARL4C, ITK, CDH3, GZMB, and KLRD1), which were identified from 104 TILCD8Ts-specific DEGs. Our results showed that compared to the cr-TILCD8TSig-low subgroup, the -high subgroup had a poorer distant relapse-free survival (DRFS) in the GSE25066 cohort and worse progression-free survival (PFS) in the TCGA-BRCA cohort. Univariate and multivariate Cox regression analyses also demonstrated that cr-TILCD8TSig was an independent prognostic factor in the two independent cohorts. Furthermore, cr-TILCD8TSig-low patients benefited more from chemotherapy and immunotherapy than cr-TILCD8TSig-high patients. Besides, we found cell transmembrane signal transduction and the ECM may provide the molecular basis for resistance to antitumor agents in the cr-TILCD8Sig-high subgroup. For genomic alterations, we revealed that mutations in PIK3CA, DMD, and APOB were more common in the cr-TILCD8Sig-high subgroup than in the cr-TILCD8Sig-low subgroup. A nomogram was finally constructed with good discrimination and calibration. Conclusions: cr-TILCD8TSig is a useful tool to independently predict prognosis, chemotherapy response, and immunotherapy outcomes in patients with breast cancer.

Upregulation of Superenhancer-Driven LncRNA FASRL by USF1 Promotes De Novo Fatty Acid Biosynthesis to Exacerbate Hepatocellular Carcinoma.

Superenhancers drive abnormal gene expression in tumors and promote malignancy. However, the relationship between superenhancer-associated long noncoding RNA (lncRNA) and abnormal metabolism is unknown. This study identifies a novel lncRNA, fatty acid synthesis-related lncRNA (FASRL), whose expression is driven by upstream stimulatory factor 1 (USF1) through its superenhancer. FASRL promotes hepatocellular carcinoma (HCC) cell proliferation in vitro and in vivo. Furthermore, FASRL binds to acetyl-CoA carboxylase 1 (ACACA), a fatty acid synthesis rate-limiting enzyme, increasing fatty acid synthesis via the fatty acid metabolism pathway. Moreover, the expression of FASRL, USF1, and ACACA is increased, and their high expression indicates a worse prognosis in HCC patients. In summary, USF1 drives FASRL transcription via a superenhancer. FASRL binding to ACACA increases fatty acid synthesis and lipid accumulation to mechanistically exacerbate HCC. FASRL may serve as a novel prognostic marker and treatment target in HCC.

Immune Infiltration and Clinical Outcome of Super-Enhancer-Associated lncRNAs in Stomach Adenocarcinoma.

Super-enhancers (SEs) comprise large clusters of enhancers that highly enhance gene expression. Long non-coding RNAs (lncRNAs) tend to be dysregulated in cases of stomach adenocarcinoma (STAD) and are vital for balancing tumor immunity. However, whether SE-associated lncRNAs play a role in the immune infiltration of STAD remains unknown. In the present study, we identified SE-associated lncRNAs in the H3K27ac ChIP-seq datasets from 11 tumor tissues and two cell lines. We found that the significantly dysregulated SE-associated lncRNAs were strongly correlated with immune cell infiltration through the application of six algorithms (ImmuncellAI, CIBERSORT, EPIC, quantiSeq, TIMER, and xCELL), as well as immunomodulators and chemokines. We found that the expression of SE-associated lncRNA TM4SF1-AS1 was negatively correlated with the proportion of CD8+ T cells present in STAD. TM4SF1-AS1 suppresses T cell-mediated immune killing function and predicts immune response to anti-PD1 therapy. ChIP-seq, Hi-C and luciferase assay results verified that TM4SF1-AS1 was regulated by its super-enhancer. RNA-seq data showed that TM4SF1-AS1 is involved in immune and cancer-related processes or pathways. In conclusion, SE-associated lncRNAs are involved in the tumor immune microenvironment and act as indicators of clinical outcomes in STAD. This study highlights the importance of SE-associated lncRNAs in the immune regulation of STAD.