DNA-methylation-mediated activating of lncRNA SNHG12 promotes temozolomide resistance in glioblastoma
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Open Access
- 10 February 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in Molecular Cancer
- Vol. 19 (1), 1-19
- https://doi.org/10.1186/s12943-020-1137-5
Abstract
Background Accumulating evidence shows that long noncoding RNAs (lncRNAs) are important regulator molecules involved in diverse biological processes. Acquired drug resistance is a major challenge in the clinical treatment of glioblastoma (GBM), and lncRNAs have been shown to play a role in chemotherapy resistance. However, the underlying mechanisms by which lncRNA mediates TMZ resistance in GBM remain poorly characterized. Methods Quantitative reverse transcription PCR (qRT-PCR) and fluorescence in situ hybridization assays were used to detect small nucleolar RNA host gene 12 (SNHG12) levels in TMZ-sensitive and TMZ-resistant GBM cells and tissues. The effects of SNHG12 on TMZ resistance were investigated through in vitro assays (western blots, colony formation assays, flow cytometry assays, and TUNEL assays). The mechanism mediating the high expression of SNHG12 in TMZ-resistant cells and its relationships with miR-129-5p, mitogen-activated protein kinase 1 (MAPK1), and E2F transcription factor 7 (E2F7) were determined by bioinformatic analysis, bisulfite amplicon sequencing, methylation-specific PCR, dual luciferase reporter assays, chromatin immunoprecipitation assays, RNA immunoprecipitation assays, immunofluorescence, qRT-PCR, and western blot. For in vivo experiments, an intracranial xenograft tumor mouse model was used to investigate SNHG12 function. Results SNHG12 was upregulated in TMZ-resistant cells and tissues. Overexpression of SNHG12 led to the development of acquired TMZ resistance, while knockdown of SNHG12 restored TMZ sensitivity. An abnormally low level of DNA methylation was detected within the promoter region of SNHG12, and loss of DNA methylation made this region more accessible to the Sp1 transcription factor (SP1); this indicated that methylation and SP1 work together to regulate SNHG12 expression. In the cytoplasm, SNHG12 served as a sponge for miR-129-5p, leading to upregulation of MAPK1 and E2F7 and endowing the GBM cells with TMZ resistance. Disinhibition of MAPK1 regulated TMZ-induced cell apoptosis and the G1/S cell cycle transition by activating the MAPK/ERK pathway, while E2F7 dysregulation was primarily associated with G1/S cell cycle transition. Clinically, SNHG12 overexpression was associated with poor survival of GBM patients undergoing TMZ treatment. Conclusion Our results suggest that SNHG12 could serve as a promising therapeutic target to surmount TMZ resistance, thereby improving the clinical efficacy of TMZ chemotherapy.Keywords
Funding Information
- National Natural Science Foundation of China (No. 81772679, 81472362, and 81772951)
- Jiangsu Province’s Key Discipline (ZDXKA2016001)
- Priority Academic Program Development of Jiangsu Higher Education Institutions
- Science and Technology Development Fund of Nanjing Medical University (JX218317201711010)
- Key R&D Program (Social Development) Projects in Jiangsu Province (KY218ZX180013)
This publication has 50 references indexed in Scilit:
- Global Positioning System: Understanding Long Noncoding RNAs through Subcellular LocalizationMolecular Cell, 2019
- Dual functions for OVAAL in initiation of RAF/MEK/ERK prosurvival signals and evasion of p27-mediated cellular senescenceProceedings of the National Academy of Sciences of the United States of America, 2018
- Serum long noncoding RNA HOTAIR as a novel diagnostic and prognostic biomarker in glioblastoma multiformeMolecular Cancer, 2018
- MicroRNA-30a-5p inhibits gallbladder cancer cell proliferation, migration and metastasis by targeting E2F7Cell Death & Disease, 2018
- Long Noncoding RNA NEAT1, Regulated by the EGFR Pathway, Contributes to Glioblastoma Progression Through the WNT/β-Catenin Pathway by Scaffolding EZH2Clinical Cancer Research, 2018
- Endogenous microRNA sponges: evidence and controversyNature Reviews Genetics, 2016
- Comprehensive Genomic Characterization of Long Non-coding RNAs across Human CancersCancer Cell, 2015
- A Functional Genomic Approach Identifies FAL1 as an Oncogenic Long Noncoding RNA that Associates with BMI1 and Represses p21 Expression in CancerCancer Cell, 2014
- Interplay between the Cancer Genome and EpigenomeCell, 2013
- A restricted cell population propagates glioblastoma growth after chemotherapyNature, 2012