Project description:Non-coding RNAs, including Inc-RNA and miRNA, have been reported to regulate gene expression and are associated with cancer progression. MicroRNA-561-3p (miR-561-3p), as a tumor suppressor, has been reported to play a role in preventing cancer cell progression, and MALAT1 (Lnc-RNA) have also been demonstrated to promote malignancy in various cancers, such as breast cancer (BC). In this study, we aimed to determine the correlation between miR-561-3p and MALAT1 and their roles in breast cancer progression. The expression of MALAT1, mir-561-3p, and topoisomerase alpha 2 (TOP2A) as a target of miR-561-3p was determined in BC clinical samples and cell lines via qRT-PCR. The binding site between MALAT1, miR-561-3p, and TOP2A was investigated by performing the dual luciferase reporter assay. MALAT1 was knocked down by siRNA, and cell proliferation, apoptotic assays, and cell cycle arrest were evaluated. MALAT1 and TOP2A were significantly upregulated, while mir-561-3p expression was downregulated in BC samples and cell lines. MALAT1 knockdown significantly increased miR-561-3p expression, which was meaningfully inverted by co-transfection with the miR 561-3p inhibitor. Furthermore, the knockdown of MALAT1 by siRNA inhibited proliferation, induced apoptosis, and arrested the cell cycle at the G1 phase in BC cells. Notably, the mechanistic investigation revealed that MALAT1 predominantly acted as a competing endogenous RNA in BC by regulating the miR-561-3p/TOP2A axis. Based on our results, MALAT1 upregulation in BC may function as a tumor promoter in BC via directly sponging miRNA 561-3p, and MALAT1 knockdown serves a vital antitumor role in BC cell progression through the miR-561-3p/TOP2A axis.
Project description:Gastric cancer (GC) causes nearly one million deaths worldwide each year. However, the molecular pathway of GC development remains unclear. Increasing evidences have shown that microRNAs (miRNAs) are highly associated with tumor development. However, relative little is known about the potential role of miRNAs in gastric cancer development. In the present study, we showed that miR-561 was down-regulated frequently in human GCs cell lines and tissues, and its expression was associated with tumor-node-metastasis (pTNM) stage. Enforced expression of miR-561 in GC cells inhibited cell proliferation and invasion in vitro. In contrast, knockdown of miR-561 had the opposite effect on cell proliferation and invasion. Moreover, c-Myc was identified as a potential miR-561 target. Further studies confirmed that miR-561 suppressed the expression of c-Myc by directly binding to its 3'-untranslated region. Restoration of c-Myc in miR-561-overexpressed GC cells reversed the suppressive effects of miR-561 and c-Myc was inversely correlated with miR-561 expression in GC tissues. These results demonstrate that miR-561 acts as a novel tumor suppressor in GC by targeting c-Myc gene and inhibiting GC cells proliferation and invasion. These findings contribute to current understanding of the functions of miR-561 in GC.
Project description:MicroRNAs (miRNAs) delivered by gastric cancer (GC)-secreted extracellular vesicles (GC-EVs) are associated with the immune escape in GC. Microarray analysis based on the GEO: GSE112369 dataset identified the presence of poorly expressed CXXC finger protein 4 (CXXC4) in GC, which was validated in clinical samples of GC patients. Moreover, prediction based on TargetScan analysis demonstrated the putative miR-675-3p binding site in the 3' UTR region of CXXC4. Thereby, our study aims to determine the role of GC-EV-encapsulated miR-675-3p in GC. First, CXXC4 was found to be negatively correlated with programmed cell death 1 ligand 1 (PD-L1). The effects of mitogen-activated protein kinase (MAPK) signaling on GC were evaluated using activator of the MAPK pathway. The overexpression of CXXC4 led to a downregulated MAPK signaling pathway, thus decreasing PD-L1 expression to augment the proliferation and activation of T cells co-cultured with GC HGC-27 cells. GC-EV-encapsulated miR-675-3p negatively regulated the expression of its target gene CXXC4. GC-EV-encapsulated miR-675-3p increased PD-L1 expression to stimulate the immune escape in vitro and EV-encapsulated miR-675-3p accelerated cisplatin resistance in vivo. Collectively, the aforementioned findings present a mechanism in which EV-mediated miR-675-3p upregulates PD-L1 expression, promoting immune escape in GC.
Project description:Immunosuppression of tumour-infiltrating lymphocytes (TIL) is a common feature of advanced cancer, but its biological basis has remained obscure. We demonstrate here a molecular link between epithelial-to-mesenchymal transition (EMT) and CD8(+) TIL immunosuppression, two key drivers of cancer progression. We show that microRNA-200 (miR-200), a cell-autonomous suppressor of EMT and metastasis, targets PD-L1. Moreover, ZEB1, an EMT activator and transcriptional repressor of miR-200, relieves miR-200 repression of PD-L1 on tumour cells, leading to CD8(+) T-cell immunosuppression and metastasis. These findings are supported by robust correlations between the EMT score, miR-200 levels and PD-L1 expression in multiple human lung cancer datasets. In addition to revealing a link between EMT and T-cell dysfunction, these findings also show that ZEB1 promotes metastasis through a heretofore unappreciated cell non-autonomous mechanism, and suggest that subgroups of patients in whom malignant progression is driven by EMT activators may respond to treatment with PD-L1 antagonists.
Project description:Programmed death-ligand 1 (PD-L1) is a crucial target for lung cancer immunotherapy. In lung cancer patients with high PD-L1 expression, blocking or reducing its expression can inhibit tumor growth. PD-L1 is regulated by signaling pathways, transcription factors and epigenetic factors, such as the GSK3β/β-catenin pathway, P53 protein and EMT. In our previous study, succinate dehydrogenase 5 (SDH5) was reported to regulate ZEB1 expression, induce EMT and lead to lung cancer metastasis via the GSK3β/β-catenin pathway. It is possible that SDH5 is involved in the mechanisms of PD-L1 regulation.In the present study, we observed a negative correlation between the expression of PD-L1 and SDH5 in vivo and in vitro. The examination of patient tissues also confirmed our results. Furthermore, we also found that SDH5 could reverse PD-L1 expression by the GSK3β/β-catenin/ZEB1 pathways. All these results reveal that SDH5 regulates PD-L1 expression and suggest that SDH5 can be used as a marker to predict tumor immune micro-states and provide guidance for clinical immunotherapy.
Project description:Tumor cells can evade antitumor immune response by expressing the PD-L1 ligand, leading to the inhibition of PD-1-expressing T lymphocytes. The mechanisms that regulate PD-L1 expression in cancer cells are imperfectly characterized. The transcription factor ZEB1, a major regulator of phenotype switching in melanoma cells, was shown to promote immune escape in melanoma by repressing T cell infiltration. Using inducible models of phenotype switching and ZEB1 gain/loss-of-function melanoma, we show that ZEB1 binds to the CD274 (PD-L1) promoter, directly enhancing PD-L1 mRNA transcription and its expression at the cell membrane. Furthermore, using single-cell spatial analyses on human primary melanoma samples, we demonstrate the correlation of ZEB1 and PD-L1 expression in tumor cells. Overall, these data identify ZEB1-mediated regulation of PD-L1 tumor expression as a mechanism that could contribute to immune escape in melanoma.
Project description:Diffuse large B cell lymphoma (DLBCL) is the commonest disorder derived from the B-lymphocytes. Inhibiting the immune checkpoint through naturalizing programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) is proved to be a successful therapeutic regime for lymphoma. Long non-coding RNAs (lncRNAs) are unceasingly reported to be promising biological targets for the cancer therapies. This study planned to explore the regulation of small nucleolar RNA host gene 14 (SNHG14) on DLBCL. SNHG14 level in DLBCL samples and cell lines was analyzed by GEPIA bioinformatics tool and RT-qPCR. Biological functions of SNHG14 in DLBCL were detected by CCK-8, colony formation, and transwell invasion assays. Molecular interaction was determined by RNA immunoprecipitation (RIP) and luciferase reporter assays. MiR-5590-3p-related pathway was identified through KEGG pathway analysis applying DAVID6.8 online bioinformatics tool. Effect of SNHG14 on CD8+ T cells was detected by flow cytometry. Results depicted that SNHG14 was upregulated in DLBCL and its depletion retarded proliferation, migration and epithelial-to-mesenchymal transition (EMT). Mechanistically, SNHG14 sponged miR-5590-3p to upregulate Zinc finger E-box binding homeobox 1 (ZEB1), and ZEB1 transcriptionally activated SNHG14 and PD-L1 to promote the immune evasion of DLBCL cells. In conclusion, we firstly showed that SNHG14/miR-5590-3p/ZEB1 positive feedback loop promoted diffuse large B cell lymphoma progression and immune evasion through regulating PD-1/PD-L1 checkpoint, indicating that targeting SNHG14 was a potential approach to improve the efficacy of immunotherapy in DLBCL.
Project description:BackgroundLong non-coding RNAs (LncRNAs) have been implicated as critical regulators of cancer tumorigenesis and progression. However, their functions and molecular mechanisms in colorectal cancer (CRC) still remain to be further elucidated.MethodsLINC00460 was identified by differential analysis between human CRC and normal tissues and verified by in situ hybridization (ISH) and qRT-PCR. We investigated the biological functions of LINC00460 in CRC by in vitro and in vivo experiments. We predicted the mechanism and downstream functional molecules of LINC00460 by bioinformatics analysis, and confirmed them by dual luciferase reporter gene assay, RNA immunoprecipitation (RIP), RNA pull-down, etc. RESULTS: LINC00460 was found to be significantly overexpressed in CRC and associated with poor prognosis. Overexpression of LINC00460 promoted CRC cell immune escape and remodeled a suppressive tumor immune microenvironment, thereby promoting CRC proliferation and metastasis. Mechanistic studies showed that LINC00460 served as a molecular sponge for miR-186-3p, and then promoted the expressions of MYC, CD47 and PD-L1 to facilitate CRC cell immune escape. We also demonstrated that MYC upregulated LINC00460 expression at the transcriptional level and formed a positive feedback loop.ConclusionsThe LINC00460/miR-186-3p/MYC feedback loop promotes CRC cell immune escape and subsequently facilitates CRC proliferation and metastasis. Our findings provide novel insight into LINC00460 as a CRC immune regulator, and provide a potential therapeutic target for CRC patients.
Project description:Accumulating literatures have indicated that long non-coding RNAs (lncRNAs) are crucial molecules in tumor progression in various human cancers, including colorectal cancer (CRC). However, the clinical significance and regulatory mechanism of a vast majority of lncRNAs in CRC remain to be determined. The current study aimed to explore the function and molecular mechanism of lncRNA AC010789.1 in CRC progression. AC010789.1 found to be overexpressed in CRC tissues and cells. High expression of AC010789.1 was associated with lymph node metastasis and poor prognosis. Moreover, AC010789.1 silencing inhibited proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in vitro as well as tumorigenesis and metastasis in vivo. Mechanistically, we demonstrated that repression of AC010789.1 promoted miR-432-3p expression, and miR-432-3p directly binds to ZEB1. We then proved the anti-tumor role of miR-432-3p in CRC, showing that the inhibitory effect of AC010789.1 knockdown on CRC cells was achieved by the upregulation of miR-432-3p but downregulation of ZEB1. We also established that silencing AC010789.1 suppressed the Wnt/β-catenin signaling pathway. However, this inhibitory effect was partially counteracted by inhibition of miR-432-3p. In summary, these results reveal that silencing AC010789.1 suppresses CRC progression via miR-432-3p-mediated ZEB1 downregulation and suppression of the Wnt/β-catenin signaling pathway, highlighting a potentially promising strategy for CRC treatment.