title: Involvement of endoplasmic reticulum stress and p53 in lncRNA MEG3-induced human hepatoma HepG2 cell apoptosis.
abstract: Long non-coding RNAs (lncRNAs) play important roles in diverse biological processes. Although downregulation of lncRNA maternally expressed gene 3 (MEG3) has been identified in several types of cancers, little is known concerning its biological role and regulatory mechanism in hepatoma. Our previous studies demonstrated that MEG3 induces apoptosis in a p53-dependent manner. The aim of the present study was to determine whether endoplasmic reticulum (ER) stress is involved in MEG3‑induced apoptosis. Recombinant lentiviral vectors containing MEG3 (Lv‑MEG3) were constructed and transfected into HepG2 cells. A 3‑(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, RT‑PCR, flow cytometry, western blot analysis, immunofluorescence and immunohistochemistry were applied. Transfected HepG2 cells were also transplanted into nude mice, and the tumor growth curves were determined. The results showed that the recombinant lentivirus of MEG3 was transfected successfully into the HepG2 cells and the expression level of MEG3 was significantly increased. Ectopic expression of MEG3 inhibited HepG2 cell proliferation in vitro and in vivo, and also induced apoptosis. Ectopic expression of MEG3 increased ER stress‑related proteins 78‑kDa glucose‑regulated protein (GRP78), inositol‑requiring enzyme 1 (IRE1), RNA‑dependent protein kinase‑like ER kinase (PERK), activating transcription factor 6 (ATF6), C/EBP homologous protein (CHOP), caspase‑3, as well as p53 and NF‑κB expression accompanied by NF‑κB translocation from the cytoplasm to the nucleus. Furthermore, inhibition of NF‑κB with Bay11‑7082 decreased p53 expression in the MEG3‑transfected cells. These results indicate that MEG3 inhibits cell proliferation and induces apoptosis, partially via the activation of the ER stress and p53 pathway, in which NF‑κB signaling is required for p53 activation in ER stress.
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Rui-Pei
authors.initials: RP
authors.lastname: Chen
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Zhen-Lun
authors.initials: ZL
authors.lastname: Huang
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Li-Xuan
authors.initials: LX
authors.lastname: Liu
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Meng-Qi
authors.initials: MQ
authors.lastname: Xiang
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Li
authors.affiliation: Department of Information, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Jia-Lin
authors.initials: JL
authors.lastname: Feng
authors.affiliation: Department of Neurosurgery, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China.
authors.forename: Ling-Fei
authors.initials: LF
authors.lastname: Wu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D005434:Flow Cytometry; D056945:Hep G2 Cells; D064593:Heterografts; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D062085:RNA, Long Noncoding / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; C498907:MEG3 non-coding RNA, human; D062085:RNA, Long Noncoding; D016159:Tumor Suppressor Protein p53