Long Noncoding RNA MEG3 Interacts with p53 Protein and Regulates Partial p53 Target Genes in Hepatoma Cells
October
Long Noncoding RNA MEG3 Interacts with p53 Protein and Regulates Partial p53 Target Genes in Hepatoma Cells
Juanjuan Zhu 0 1
Shanshan Liu 0 1
Fuqiang Ye 0 1
Yuan Shen 0 1
Yi Tie 0 1
Jie Zhu 0 1
Lixin Wei 0 1
Yinghua Jin 0 1
Hanjiang Fu 0 1
Yongge Wu 0 1
Xiaofei Zheng 0 1
0 1 Beijing Institute of Radiation Medicine , Beijing , China , 2 College of Life Sciences, Jilin University , Changchun , China , 3 School of Life Science and Technology, China Pharmaceutical University , Nanjing , China , 4 Department of Pathology, General Hospital of PLA , Beijing , China
1 Editor: Thomas G Hofmann, German Cancer Research Center , GERMANY
Maternally Expressed Gene 3 (MEG3) encodes a lncRNA which is suggested to function as a tumor suppressor. Previous studies suggested that MEG3 functioned through activation of p53, however, the functional properties of MEG3 remain obscure and their relevance to human diseases is under continuous investigation. Here, we try to illuminate the relationship of MEG3 and p53, and the consequence in hepatoma cells. We find that transfection of expression construct of MEG3 enhances stability and transcriptional activity of p53. Deletion analysis of MEG3 confirms that full length and intact structure of MEG3 are critical for it to activate p53-mediated transactivation. Interestingly, our results demonstrate for the first time that MEG3 can interact with p53 DNA binding domain and various p53 target genes are deregulated after overexpression of MEG3 in hepatoma cells. Furthermore, results of qRT-PCR have shown that MEG3 RNA is lost or reduced in the majority of HCC samples compared with adjacent non-tumorous samples. Ectopic expression of MEG3 in hepatoma cells significantly inhibits proliferation and induces apoptosis. In conclusion, our data demonstrates that MEG3 functions as a tumor suppressor in hepatoma cells through interacting with p53 protein to activate p53-mediated transcriptional activity and influence the expression of partial p53 target genes.
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Data Availability Statement: All relevant data are
within the paper and its Supporting Information file.
The microarray data discussed in this paper has
been deposited in NCBI Gene Expression Omnibus
and the GEO accession number is GSE69916.
Funding: This work was supported partially by
Chinese State Key Projects for Basic Research
(2013CB910801), National 863 plans projects
(2012AA022501), and Chinese National Natural
Science Foundation projects (31170713, 31270836,
31370760). The funders had no role in study design,
data collection and analysis, decision to publish, or
preparation of the manuscript.
ncRNAs are functional RNA molecules that are not translated into proteins, including transfer
RNAs (tRNAs), ribosomal RNAs (rRNAs), microRNAs (miRNAs), small nucleolar RNAs
(snoRNAs), Piwi-RNAs and long non-coding RNAs (lncRNAs) [1]. A growing number of
literatures point to the critical regulatory role of ncRNAs in normal cellular physiological
processes as well as the contribution of aberrant ncRNA expression to cancer biology [2]. Among
them, lncRNAs which are widely distributed in mammals, are a class of RNA molecules with
Competing Interests: The authors have declared
that no competing interests exist.
more than 200 nucleotides that function as RNAs with little or no protein-coding capacity [3].
Recently, researches demonstrated that lncRNAs played an important role in cell physiological
activities, and participated in development of varieties of tumors and other diseases via
multiple levels as epigenetics, transcription and post-transcription [4–7]. Deregulation of lncRNAs
has been proposed to be involved in hepatocarcinogenesis, such as HEIH, HUCL, MVIH, H19,
TUC338 and MEG3 [8–13].
MEG3 is homologous with mouse maternally imprinted gene Gtl2, a maternally expressed
imprinted gene first identified by Miyoshi N et al. in 2000 [14]. MEG3 belongs to DLK1-MEG3
imprinted region at chromosome 14q32.3 in human and transcripts an mRNA-like RNA with
a length of ~1.6kb [15]. Due to the TATA box within the gene promoter and RNA transcript
with a poly(A) tail, MEG3 is a target gene of RNA polymeraseⅡ [16]. Sixteen different variants
generated via alternative splicing of 10 exons within MEG3 gene have been proven, as sixteen
human MEG3 cDNA isoforms have been reported. Among them, variant 1 (NR_002766),
otherwise known as MEG3, is the predominant transcript [17, 18].
Previous reports demonstrated that MEG3 is highly expressed in normal human tissue.
However, its expression is lost or decreases in major human tumors, such as meningioma,
colon cancer, nasopharyngeal carcinoma, and leukemia [19]. Moreover, it has been reported
that MEG3 functions as a tumor suppressor through activating p53 pathway [19–22]. P53
functions as a transcriptional factor through mediating tumor suppression. Previous data
demonstrated that MEG3 is capable of inducing a significant increase in p53 protein level.
However, the function of MEG3 gene has not yet been (...truncated)