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LncRNA SAMD12-AS1 promotes cell proliferation and inhibits apoptosis by interacting with NPM1.

ABSTRACT: Chronic hepatitis B virus infection is a major risk factor for hepatocellular carcinoma. HBV infection affects lncRNA expression in infected cells, but the detailed mechanism and biological significance are not yet clear. In this study, we focused on exploring the function of the HBV-upregulated lncRNA SAMD12-AS1 in cell proliferation. We found that there is a higher level of SAMD12-AS1 expression in tumors than in adjacent nontumorous liver tissues. We showed that ectopic expression of SAMD12-AS1 promotes cell growth and blocks apoptosis, while knockdown of SAMD12-AS1 inhibits cell proliferation and enhances etoposide-induced apoptosis. Using RNA immunoprecipitation and mass spectrometry, we determined that SAMD12-AS1 interacts with NPM1 and confirmed that SAMD12-AS1(1-350) is required for the interaction with NPM1. As it is known that NPM1 interacts with the E3 ligase HDM2 and reduces HDM2-mediated p53 degradation, we examined whether SAMD12-AS1 can affect p53 stability. Overexpression of SAMD12-AS1 caused a reduction in p53 protein levels by shortening its half-life. Conversely, knockdown of SAMD12-AS1 prolonged the half-life of p53. We further demonstrated that SAMD12-AS1 increased the interaction of HDM2 and p53 and enhanced p53 ubiquitination. Our findings reveal that HBV-upregulated SAMD12-AS1 regulates cell proliferation and apoptosis via the NPM1-HDM2-p53 axis.

SUBMITTER: Liu Q

PROVIDER: S-EPMC6691116 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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LncRNA SAMD12-AS1 promotes cell proliferation and inhibits apoptosis by interacting with NPM1.

Liu Qi Q Liu Ningning N Shangguan Qilin Q Zhang Fang F Chai Wenjia W Tong Xiaomei X Zhao Xin X Li Zhiwei Z Qi Dandan D Ye Xin X

Scientific reports 20190812 1

Chronic hepatitis B virus infection is a major risk factor for hepatocellular carcinoma. HBV infection affects lncRNA expression in infected cells, but the detailed mechanism and biological significance are not yet clear. In this study, we focused on exploring the function of the HBV-upregulated lncRNA SAMD12-AS1 in cell proliferation. We found that there is a higher level of SAMD12-AS1 expression in tumors than in adjacent nontumorous liver tissues. We showed that ectopic expression of SAMD12-A ...[more]

PMID: 31406141

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Project description:BackgroundAcute myeloid leukemia (AML) with mutated nucleophosmin (NPM1), which displays a distinct long noncoding RNA (lncRNA) expression profile, has been defined as a unique subgroup in the new classification of myeloid neoplasms. However, the biological roles of key lncRNAs in the development of NPM1-mutated AML are currently unclear. Here, we aimed to investigate the functional and mechanistic roles of the lncRNA HOTAIRM1 in NPM1-mutated AML.MethodsThe expression of HOTAIRM1 was analyzed with a public database and further determined by qRT-PCR in NPM1-mutated AML samples and cell lines. The cause of upregulated HOTAIRM1 expression was investigated by luciferase reporter, chromatin immunoprecipitation and ubiquitination assays. The functional role of HOTAIRM1 in autophagy and proliferation was evaluated using western blot analysis, immunofluorescence staining, a Cell Counting Kit-8 (CCK-8) assay, a 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, flow cytometric analyses and animal studies. The action mechanism of HOTAIRM1 was explored through RNA fluorescence in situ hybridization, RNA pulldown and RNA immunoprecipitation assays.ResultsHOTAIRM1 was highly expressed in NPM1-mutated AML. High HOTAIRM1 expression was induced in part by mutant NPM1 via KLF5-dependent transcriptional regulation. Importantly, HOTAIRM1 promoted autophagy and proliferation both in vitro and in vivo. Mechanistic investigations demonstrated that nuclear HOTAIRM1 promoted EGR1 degradation by serving as a scaffold to facilitate MDM2-EGR1 complex formation, while cytoplasmic HOTAIRM1 acted as a sponge for miR-152-3p to increase ULK3 expression.ConclusionsTaken together, our findings identify two oncogenic regulatory axes in NPM1-mutated AML centered on HOTAIRM1: one involving EGR1 and MDM2 in the nucleus and the other involving the miR-152-3p/ULK3 axis in the cytoplasm. Our study indicates that HOTAIRM1 may be a promising therapeutic target for this distinct leukemia subtype.

Project description:GBM (Glioblastoma multiform) is the most malignant tumor type of the central nervous system and has poor diagnostic and clinical outcomes. LncRNAs (Long non-coding RNAs) have been reported to participate in multiple biological and pathological processes, but their underlying mechanism remains poorly understood. Here, we aimed to explore the role of the lncRNA HAS2-AS1 (HAS2 antisense RNA 1) in GBM. GSE103227 was analyzed, and qRT-PCR was performed to measure the expression of HAS2-AS1 in GBM. FISH (Fluorescence in situ hybridization) was performed to verify the localization of HAS2-AS1. The interaction between HAS2-AS1 and miR-137 (microRNA-137) was predicted by LncBook and miRcode followed by dual-luciferase reporter assays, and the relationships among HAS2-AS1, miR-137 and LSD1 (lysine-specific demethylase 1) were assessed by WB (western blot) and qRT-PCR. Colony formation and CCK-8 (cell counting kit-8) assays were performed as functional tests. In vivo, nude mice were used to confirm the function of HAS2-AS1. HAS2-AS1 expression was upregulated in GBM cell lines, and HAS2-AS1 was localized mainly in the cytoplasm. In vitro, high HAS2-AS1 expression promoted proliferation, and knockdown of HAS2-AS1 significantly inhibited proliferation. Furthermore, HAS2-AS1 functioned as a ceRNA (competing endogenous RNA) of miR-137, leading to the disinhibition of its downstream target LSD1. The miR-137 level was downregulated by HAS2-AS1 overexpression and upregulated by HAS2-AS1 knockdown. In a subsequent study, LSD1 expression was negatively regulated by miR-137, while miR-137 reversed the LSD1 expression levels caused by HAS2-AS1. These results were further supported by the nude mouse tumorigenesis experiment; compared with xenografts with high HAS2-AS1 expression, the group with low levels of HAS2-AS1 exhibited suppressed proliferation and better survival. We conclude that lncRNA HAS2-AS1 promotes proliferation by functioning as a miR-137 decoy to increase LSD1 levels and thus might be a possible biomarker for GBM.

Dataset Information

LncRNA SAMD12-AS1 promotes cell proliferation and inhibits apoptosis by interacting with NPM1.

Publications

LncRNA SAMD12-AS1 promotes cell proliferation and inhibits apoptosis by interacting with NPM1.

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