C-Myc-activated USP2-AS1 suppresses senescence and promotes tumor progression via stabilization of E2F1 mRNA
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ABSTRACT:
SUBMITTER: Li B
PROVIDER: S-EPMC8551278 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Dysregulation of Hippo signaling by long non-coding RNA (lncRNA) contributes to colon adenocarcinoma (COAD) progression, while the underlying mechanisms remain elusive. Our study shows that lncRNA USP2-AS1 is a Yes-associated protein 1 (YAP1) binding lncRNA, and inactivates Hippo signaling in COAD cells. Moreover, our data indicated that USP2-AS1 lowered the phosph-YAP (S127), elevated the total level of YAP1, and triggered the expression of downstream target genes in COAD cells. The loss- and gain-of function assays demonstrated that USP2-AS1 promotes cellular proliferation and metastasis of COAD cells. Clinically, the USP2-AS1 levels were significantly elevated in COAD tissues and were positively correlated with tumor grade, size, and TNM stage. Collectively, these findings demonstrated that USP2-AS1 modulates and regulates Hippo signaling in COAD and could be a valuable therapeutic target.
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Project description:Mounting literatures have revealed the crucial effects of long noncoding RNA (lncRNA) in various cancers, including glioma. HNF1A-AS1, a novel lncRNA, is reported to modulate tumorigenesis and development of multiple cancers. However, the tumorigenic function of lncRNA HNF1A-AS1 in glioma remains largely unknown. quantitative reverse transcription and polymerase chain reaction and western blot assays were applied to evaluate the expression of relevant mRNAs and proteins. 5-Ethynyl-2'- deoxyuridine, terminal deoxynucleotidyl transferase dUTP nick-end labeling, flow cytometry, and transwell assays were conducted for examining the influence of HNF1A-AS1 on glioma cell functions. The relationship among RNAs was investigated by mechanical experiments. The results demonstrated that HNF1A-AS1 was predominantly highly expressed in glioma cell lines compared with nontumor glial epithelial cell, which was associated with the stimulation of transcription factor myelocytomatosis oncogene. Knockdown of HNF1A-AS1 remarkably inhibited glioma cells proliferation, migration, and invasion, while accelerating cell apoptosis in vitro. Mechanically, HNF1A-AS1 served as a miR-32-5p sponge. Moreover, SOX4 was discovered as a target of miR-32-5p. Inhibited miR-32-5p or upregulated SOX4 could markedly counteract the inhibitory effects of silencing HNF1A-AS1 on glioma malignant biological behaviors. HNF1A-AS1 exerted oncogenic property in glioma progression via upregulating miR-32-5p-mediated SOX4 expression, suggesting potential novel therapeutic target for future glioma treatment.
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Project description:BackgroundAcute myeloid leukemia (AML) is the most common type of leukemia in adults. Its therapy has not significantly improved during the past four decades despite intense research efforts. New molecularly targeted therapies are in great need. The proto-oncogene c-Myc (MYC) is an attractive target due to its transactivation role in multiple signaling cascades. Deregulation of the MYC is considered one of a series of oncogenic events required for tumorigenesis. However, limited knowledge is available on which mechanism underlie MYC dysregulation and how long non-coding RNAs (lncRNAs) are involved in MYC dysregulation in AML.MethodsAML microarray chips and public datasets were screened to identify novel lncRNA GAS6-AS1 was dysregulated in AML. Gain or loss of functional leukemia cell models were produced, and in vitro and in vivo experiments were applied to demonstrate its leukemogenic phenotypes. Interactive network analyses were performed to define intrinsic mechanism.ResultsWe identified GAS6-AS1 was overexpressed in AML, and its aberrant function lead to more aggressive leukemia phenotypes and poorer survival outcomes. We revealed that GAS6-AS1 directly binds Y-box binding protein 1 (YBX1) to facilitate its interaction with MYC, leading to MYC transactivation and upregulation of IL1R1, RAB27B and other MYC target genes associated with leukemia progression. Further, lentiviral-based GAS6-AS1 silencing inhibited leukemia progression in vivo.ConclusionsOur findings revealed a previously unappreciated role of GAS6-AS1 as an oncogenic lncRNA in AML progression and prognostic prediction. Importantly, we demonstrated that therapeutic targeting of the GAS6-AS1/YBX1/MYC axis inhibits AML cellular propagation and disease progression. Our insight in lncRNA associated MYC-driven leukemogenesis may contribute to develop new anti-leukemia treatment strategies.
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Project description:BackgroundRecent evidence reveals the emerging functions of circular RNA (circRNA) and protein glycosylation in cancer progression. However, the roles of circRNA in regulating glycosyltransferase expression in gastric cancer remain to be determined.MethodsCircular RNAs (circRNAs) were validated by Sanger sequencing. Co-immunoprecipitation, mass spectrometry, and RNA sequencing assays were applied to explore protein interaction and target genes. Gene expression regulation was observed by chromatin immunoprecipitation, RNA immunoprecipitation, dual-luciferase reporter, real-time quantitative RT-PCR, and western blot assays. Gain- and loss-of-function studies were performed to observe the impacts of circRNA and its partners on the glycosylation, growth, invasion, and metastasis of gastric cancer cells.ResultsCirc-hnRNPU, an exonic circRNA derived from heterogenous nuclear ribonuclear protein U (hnRNPU), was identified to exert tumor suppressive roles in protein glycosylation and progression of gastric cancer. Mechanistically, circ-hnRNPU physically interacted with non-POU domain containing octamer binding (NONO) protein to induce its cytoplasmic retention, resulting in down-regulation of glycosyltransferases (GALNT2, GALNT6, MGAT1) and parental gene hnRNPU via repression of nuclear NONO-mediated c-Myc transactivation or cytoplasmic NONO-facilitated mRNA stability. Rescue studies indicated that circ-hnRNPU inhibited the N- and O-glycosylation, growth, invasion, and metastasis of gastric cancer cells via interacting with NONO protein. Pre-clinically, administration of lentivirus carrying circ-hnRNPU suppressed the protein glycosylation, tumorigenesis, and aggressiveness of gastric cancer xenografts. In clinical cases, low circ-hnRNPU levels and high NONO or c-Myc expression were associated with poor survival outcome of gastric cancer patients.ConclusionsThese findings indicate that circ-hnRNPU inhibits NONO-mediated c-Myc transactivation and mRNA stabilization essential for glycosylation and cancer progression.
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Project description:The placenta is essential for reproductive success. The murine placenta includes polyploid giant cells that are crucial for its function. Polyploidy occurs broadly in nature but its regulators and significance in the placenta are unknown. We have discovered that many murine placental cell types are polyploid and have identified factors that license polyploidy using single-cell RNA sequencing. Myc is a key regulator of polyploidy and placental development, and is required for multiple rounds of DNA replication, likely via endocycles, in trophoblast giant cells. Furthermore, MYC supports the expression of DNA replication and nucleotide biosynthesis genes along with ribosomal RNA. Increased DNA damage and senescence occur in trophoblast giant cells without Myc, accompanied by senescence in the neighboring maternal decidua. These data reveal Myc is essential for polyploidy to support normal placental development, thereby preventing premature senescence. Our study, combined with available literature, suggests that Myc is an evolutionarily conserved regulator of polyploidy.
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Project description:MicroRNAs (miRNAs) regulate gene expression by repressing translation or directing sequence-specific degradation of complementary mRNA. Here, we report that expression of miR-205 is significantly suppressed in melanoma specimens when compared with nevi and is correlated inversely with melanoma progression. miRNA target databases predicted E2F1 and E2F5 as putative targets. The expression levels of E2F1 and E2F5 were correlated inversely with that of miR-205 in melanoma cell lines. miR-205 significantly suppressed the luciferase activity of reporter plasmids containing the 3'-UTR sequences complementary to either E2F1 or E2F5. Overexpression of miR-205 in melanoma cells reduced E2F1 and E2F5 protein levels. The proliferative capacity of melanoma cells was suppressed by miR-205 and mediated by E2F-regulated AKT phosphorylation. miR-205 overexpression resulted in induction of apoptosis, as evidenced by increased cleaved caspase-3, poly-(ADP-ribose) polymerase, and cytochrome c release. Stable overexpression of miR-205 suppressed melanoma cell proliferation, colony formation, and tumor cell growth in vivo and induced a senescence phenotype accompanied by elevated expression of p16INK4A and other markers for senescence. E2F1 overexpression in miR-205-expressing cells partially reversed the effects on melanoma cell growth and senescence. These results demonstrate a novel role for miR-205 as a tumor suppressor in melanoma.
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Project description:ObjectiveTo examine the effects and mechanisms of AGAP2 Antisense RNA 1 (AGAP2-AS1) in progression of skin cutaneous melanoma (SKCM).MethodsAGAP2-AS1 expression and SKCM survival outcomes were assessed using bioinformatics analysis. In vitro and in vivo assays, including cell proliferation, colony formation, migration, and tumor formation assays, were performed to detect AGAP2-AS1 oncogenic effects in SKCM. RNA pull-down, RNA immunoprecipitation (RIP), and co-immunoprecipitation were used to evaluate the mechanism of AGAP2-AS1 in SKCM progression.ResultsAGAP2-AS1 was upregulated in human SKCM tissues and cells and predicted a worse prognosis. AGAP2-AS1 silencing in two SKCM cell lines inhibited cell proliferation, as well as colony formation and migration both in vitro and in vivo. The RNA pull-down assay and RIP analysis results indicated that AGAP2-AS1 interacted with bromodomain containing 7 (BRD7). AGAP2-AS1 knockdown attenuated the BRD7 and c-Myc interaction, which reduced c-Myc expression. The altered phenotypes found in AGAP2-AS1- and BRD7-deficient cells were rescued by overexpression of c-Myc.ConclusionsAGAP2-AS1 participated in oncogenesis in SKCM via the BRD7/c-Myc signaling pathway. These results suggest a molecular mechanism for AGAP2-AS1 in the carcinogenesis of SKCM.
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