Long noncoding RNA MEG3 silencing protects against hypoxia‐induced pheochromocytoma‐12 cell injury through inhibition of TIMP2 promoter methylation

Abstract

Hypoxia is a common pathological process caused by insufficient oxygen. Long noncoding RNAs (lncRNAs) have been proven to participate in this pathology. Hypoxia is reported to significantly reduce the secretion of tissue inhibitor of metalloproteinase 2 (TIMP2) and TIMP2 induces pheochromocytoma-12 (PC12) cell cycle arrest. Thus, our study aimed to explore the mechanism by which lncRNA maternally expressed gene 3 (MEG3) was implicated in hypoxia-induced PC12 cell injury through TIMP2 promoter methylation. To elucidate the potential biological significance of MEG3 and the regulatory mechanism between MEG3 and TIMP2, a hypoxia-induced PC12 cell injury model was generated. The hypoxia-exposed cells were subjected to a series of overexpression plasmids and short hairpin RNAs, followed by the measurement of levels of MEG3, TIMP2, lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), reactive oxygen species (ROS), Bcl-2-associated X protein, B-cell lymphoma-2, and caspase-3, as well as the changes in MMP, cell proliferation, apoptosis, and cell cycle progression. On the basis of the findings, MEG3 was upregulated in hypoxia-injured PC12 cells. MEG3 recruited methylation proteins DNMT3a, DNMT3b, and MBD1 and accelerated TIMP2 promoter methylation, which in turn inhibited its expression. Moreover, PC12 cells following MEG3 silencing and TIMP2 overexpression exhibited significantly decreased levels of LDH, MDA, and ROS along with cell apoptosis, yet increased SOD and MMP levels, as well as cell cycle entry to the S phase and cell proliferation. In conclusion, MEG3 silencing suppresses hypoxiainduced PC12 cell injury by inhibiting TIMP2 promoter methylation. This study may provide novel therapeutic targets for hypoxia-induced injury. K E Y W O R D S hypoxic injury, long noncoding RNA, MEG3, pheochromocytoma-12 cell, promoter methylation,TIMP2

LncRNA KCNQ1OT1 promotes the metastasis of ovarian cancer by increasing the methylation of EIF2B5 promoter

“…Nuclear-cytoplasmic fractionation assay revealed the main location of KCNQ1OT1 in nucleus of OC cells, suggesting that KCNQ1OT1 might participate in transcription regulation. LncRNAs were proved to alter DNA methylation, thereby impacting the expression of genes (Gao et al 2019 ; Yu et al 2019 ; Zheng et al 2020 ). Hence, we wondered that KCNQ1OT1 might affect methylation of EIF2B promoter.…”

The role of hypoxia-induced long noncoding RNAs (lncRNAs) in tumorigenesis and metastasis

“…LncRNA PVT1 scaffolds KAT2A to mediate H3K9 acetylation and recruit nuclear receptor binding protein TIF1β to activate NF90 expression, causing the stability of HIF-1α [ 53 ]. LncRNA MEG3 recruits DNMT3a, DNMT3b, and MBD1 to induce the hypermethylation of the TIMP2 promoter, promoting tumorigenesis [ 54 ]. Hypoxia-induced lncRNA GATA6-AS inhibits LOXL2 that removes H3K4me3 mark, inducing the expression of angiogenesis-related genes ( periostin and COX-2 ) [ 55 ].…”

Interplay within tumor microenvironment orchestrates neoplastic RNA metabolism and transcriptome diversity

“…Further, lncRNA MEG3 induces tissue inhibitor of metalloproteinase 2 (TIMP2) promoter methylation by recruiting DNMT3a, DNMT3b, and MBD1, consequently augmenting tumorigenesis under hypoxia (X. Zheng et al, 2020). Hypoxia-inducible LncRNA AK058003 causes hypomethylation of the SNCG promoter and induces its expression to promote gastric cancer metastasis (Y. .…”

“…For instance, long intergenic noncoding RNA HOTAIR acts as a scaffold for two distinct histone modification complexes: PRC2 and LSD1, which coordinate the coupled histone H3 lysine 27 methylation and lysine 4 demethylation (Tsai et al, 2010). Further, lncRNA MEG3 induces tissue inhibitor of metalloproteinase 2 (TIMP2) promoter methylation by recruiting DNMT3a, DNMT3b, and MBD1, consequently augmenting tumorigenesis under hypoxia (X. Zheng et al, 2020). Hypoxia‐inducible LncRNA AK058003 causes hypomethylation of the SNCG promoter and induces its expression to promote gastric cancer metastasis (Y. Wang, Liu, et al, 2014).…”