Circular RNAs (circRNAs) exhibit essential regulation in the malignant development of hepatocellular carcinoma (HCC). This study aims to investigate the physiological mechanisms of circ_0029343 encoded by scavenger receptor class B member 1 (SCARB1) involved in the growth and metastasis of HCC. Differentially expressed mRNAs in HCC were obtained, followed by the prediction of target genes of differentially expressed miRNAs and gene ontology and kyoto encyclopedia of genes and genomes analysis on the differentially expressed mRNAs. Moreover, the regulatory relationship between circRNAs encoded by SCARB1 and differentially expressed miRNAs was predicted. In vitro cell experiments were performed to verify the effects of circ_0029343, miR-486-5p, and SRSF3 on the malignant features of HCC cells using the gain- or loss-of-function experiments. Finally, the effects of circ_0029343 on the growth and metastasis of HCC cells in xenograft mouse models were also explored. It was found that miR-486-5p might interact with seven circRNAs encoded by SCARB1, and its possible downstream target gene was SRSF3. Moreover, SRSF3 was associated with the splicing of various RNA. circ_0029343 could sponge miR-486-5p to up-regulate SRSF3 and activate PDGF-PDGFRB (platelet-derived growth factor and its receptor, receptor beta) signaling pathway by inducing p73 splicing, thus promoting the proliferation, migration, and invasion and inhibiting apoptosis of HCC cells. In vivo, animal experiments further confirmed that overexpression of circ_0029343 could promote the growth and metastasis of HCC cells in nude mice. circ_0029343 encoded by SCARB1 may induce p73 splicing and activate the PDGF-PDGFRB signaling pathway through the miR-486-5p/SRSF3 axis, thus promoting the growth and metastasis of HCC cells.
Carcinoma, Hepatocellular , Liver Neoplasms , MicroRNAs , Humans , Animals , Mice , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/pathology , RNA, Circular/genetics , RNA, Circular/metabolism , Liver Neoplasms/genetics , Liver Neoplasms/pathology , Mice, Nude , Receptor, Platelet-Derived Growth Factor beta/genetics , Receptor, Platelet-Derived Growth Factor beta/metabolism , Cell Line, Tumor , Cell Proliferation/genetics , MicroRNAs/genetics , MicroRNAs/metabolism , Gene Expression Regulation, Neoplastic , Scavenger Receptors, Class B/genetics , Scavenger Receptors, Class B/metabolism , Serine-Arginine Splicing Factors/genetics , Serine-Arginine Splicing Factors/metabolism
Emerging evidence has validated that extracellular vesicles (EVs) regulate hepatocellular carcinoma (HCC) progression, while its role in HCC immune escape remains to be elucidated. This study investigates the role of EVs-encapsulated lysyl oxidase like-4 (LOXL4) derived from tumor cells in HCC immune escape. HCC-related microarray data sets GSE36376 and GSE87630 were obtained for differential analysis, followed by identifying the essential genes related to the prognosis of HCC patients. Bone marrow-derived macrophages were treated with EVs derived from mouse Hepa 1-6 cells and cocultured with CD8 + T cells to observe the CD8 + T-cell activity. At last, a mouse HCC orthotopic xenograft model was constructed to verify the effects of HCC cell-derived EVs on the immune escape of HCC cells and tumorigenicity in vivo by delivering LOXL4. It was found that ACAT1, C4BPA, EHHADH, and LOXL4 may be the essential genes related to the prognosis of HCC patients. On the basis of the TIMER database, there was a close correlation between LOXL4 and macrophage infiltration in HCC. Besides, STAT1 was closely related to LOXL4. In vitro experiments demonstrated that LOXL4 could induce programmed death-ligand 1 expression in macrophages and immunosuppression by activating STAT1. In vivo experiments also verified that HCC cell-derived EVs promoted the immune escape of HCC cells and tumorigenicity by delivering LOXL4. LOXL4 was delivered into macrophages via EVs to induce programmed death-ligand 1 by activating STAT1 and inhibiting the killing ability of CD8 + T cells to HCC cells, thus promoting immune escape in HCC.
Carcinoma, Hepatocellular , Extracellular Vesicles , Liver Neoplasms , Animals , Humans , Mice , B7-H1 Antigen/metabolism , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/metabolism , Cell Line, Tumor , Ligands , Liver Neoplasms/metabolism , Protein-Lysine 6-Oxidase/genetics , Protein-Lysine 6-Oxidase/metabolism , STAT1 Transcription Factor/genetics , STAT1 Transcription Factor/metabolism , Tumor Escape
BACKGROUND: Long non-coding RNA (lncRNA) HOTAIR acts importantly in liver cancer development, but its effect on radioresistance remains poorly understood. Here, our study probed into the possible impact of HOTAIR in radioresistance in liver cancer stem cells (LCSCs) and to elucidate its molecular basis. METHODS: Following sorting of stem and non-stem liver cancer cells, LCSCs were identified and subjected to RNA-seq analysis for selecting differentially expressed genes. Expression of HOTAIR was determined in liver cancer tissues and CSCs. The stemness, proliferation, apoptosis and radioresistance of LCSCs were then detected in response to altered expression of HOTAIR-LSD1-JMJD6-BRD4. RESULTS: Ectopic HOTAIR expression was found to promote radioresistance of LCSCs by maintaining its stemness. Mechanistic investigations indicated that HOTAIR recruited LSD1 to the MAPK1 promoter region and reduced the level of H3K9me2 in the promoter region, thus elevating ERK2 (MAPK1) expression. JMJD6-BRD4 complex promoted HOTAIR transcription by forming a complex and positively regulated ERK2 (MAPK1) expression, maintaining the stemness of LCSCs, and ultimately promoting their radioresistance in vitro and in vivo. CONCLUSION: Collectively, our work highlights the promoting effect of the JMJD6-BRD4 complex on the radioresistance of LCSCs through a HOTAIR-dependent mechanism.
Liver Neoplasms , RNA, Long Noncoding , Humans , Cell Cycle Proteins/genetics , Cell Line, Tumor , Cell Proliferation/genetics , Gene Expression Regulation, Neoplastic , Histone Demethylases/genetics , Histone Demethylases/metabolism , Jumonji Domain-Containing Histone Demethylases/genetics , Liver Neoplasms/genetics , Liver Neoplasms/radiotherapy , Liver Neoplasms/metabolism , Neoplastic Stem Cells/metabolism , Nuclear Proteins/metabolism , Promoter Regions, Genetic/genetics , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Transcription Factors/metabolism
It is becoming increasingly evident that key mechanisms of mesenchymal stem cell (MSC) efficacy appear to associate with paracrine activities, and the delivery of cargos through extracellular vesicles (EVs) controls the mechanistic actions of MSCs. Thus, this study clarified a possible mechanism by which EV-encapsulated NEAT1 from adipose-derived mesenchymal stem cells (ADSCs) might mediate gemcitabine resistance in pancreatic cancer (PCa). Microarray profile suggested a differentially expressed lncRNA NEAT1 in PCa, and we determined its expression in PCa cells. NEAT1 was found to be upregulated in PCa. The binding affinity among NEAT1, miR-491-5p, and Snail was identified through bioinformatic analysis and experimental validation. NEAT1 competitively bound to miR-491-5p to elevate Snail expression and diminish SOCS3 expression. PCa cells were cocultured with EVs extracted from ADSCs, followed by assessment of malignant phenotypes, tumorigenesis, and gemcitabine resistance of PCa cells using gain- or loss-of-function experiments. ADSC-derived EVs carrying NEAT1 promoted PCa cell proliferation, migration, and gemcitabine resistance in vitro and enhanced tumorigenicity in vivo by inhibiting miR-491-5p and SOCS3 and upregulating Snail. Collectively, the findings from our study found a new potential strategy for gemcitabine resistance in PCa by illustrating the mechanistic insights of oncogenic ADSC-derived EVs-loaded NEAT1 via regulating the miR-491-5p/Snail/SOCS3 axis.
INTRODUCTION: Circular RNA (CircRNA) SCARB1 plays an oncogenic role in renal cell carcinoma, while its role in other cancers is unclear. The aim of this study was to explore the role of circRNA SCARB1 in hepatocellular carcinoma (HCC). METHODS: The expression of circRNA SCARB1, mature miR-497 and miR-497 precursor in HCC and paired non-tumor tissues from 64 HCC patients were analyzed by RT-qPCR. CircRNA SCARB1 was overexpressed in HCC cells, followed by the measurement of the expression levels of both mature miR-497 and miR-497 precursor to evaluate the effects of overexpression of circRNA SCARB1 on the maturation of miR-497. The effects of circRNA SCARB1 and miR-497 on the proliferation and migration of HCC cells were assessed by CCK-8 assay and Transwell assay, respectively. RESULTS: We found that circRNA SCARB1 was upregulated in HCC. In addition, mature miR-497 and miR-497 were downregulated in HCC. Correlation analysis showed that circRNA SCARB1 was inversely correlated with mature miR-497 but not miR-497 precursor. Consistently, in HCC cells, downregulated mature miR-497, but not miR-497 precursor, was observed in HCC cells transfected with circRNA SCARB1 expression vector. Analysis of cellular behaviors showed that overexpression of circRNA SCARB1 increased the proliferation and migration of HCC cells, while overexpression of miR-497 decreased cell proliferation and migration. Moreover, overexpression of miR-497 reduced the effects of overexpression of circRNA SCARB1. DISCUSSION: Therefore, circRNA SCARB1 is upregulated in HCC and promotes HCC cell proliferation and migration by suppressing the maturation of miR-497.
