Abstract
BackgroundN6-methyladenosine (m6A) modification, the most abundant internal methylation of eukaryotic RNA transcripts, is critically implicated in RNA processing. As the largest known component in the m6A methyltransferase complex, KIAA1429 plays a vital role in m6A methylation. However, its function and mechanism in hepatocellular carcinoma (HCC) remain poorly defined.MethodsQuantitative PCR, western blot and immunohistochemistry were used to measure the expression of KIAA1429 in HCC. The effects of KIAA1429 on the malignant phenotypes of hepatoma cells were examined in vitro and in vivo. MeRIP-seq, RIP-seq and RNA-seq were performed to identify the target genes of KIAA1429.ResultsKIAA1429 was considerably upregulated in HCC tissues. High expression of KIAA1429 was associated with poor prognosis among HCC patients. Silencing KIAA1429 suppressed cell proliferation and metastasis in vitro and in vivo. GATA3 was identified as the direct downstream target of KIAA1429-mediated m6A modification. KIAA1429 induced m6A methylation on the 3′ UTR of GATA3 pre-mRNA, leading to the separation of the RNA-binding protein HuR and the degradation of GATA3 pre-mRNA. Strikingly, a long noncoding RNA (lncRNA) GATA3-AS, transcribed from the antisense strand of the GATA3 gene, functioned as a cis-acting element for the preferential interaction of KIAA1429 with GATA3 pre-mRNA. Accordingly, we found that the tumor growth and metastasis driven by KIAA1429 or GATA3-AS were mediated by GATA3.ConclusionOur study proposed a complex KIAA1429-GATA3 regulatory model based on m6A modification and provided insights into the epi-transcriptomic dysregulation in hepatocarcinogenesis and metastasis.
Highlights
N6-methyladenosine (m6A) modification, the most abundant internal methylation of eukaryotic RNA transcripts, is critically implicated in RNA processing
We confirmed KIAA1429 upregulation in 70 pairs of hepatocellular carcinoma (HCC) tissues from the West China Hospital (WCH) dataset by quantitative PCR analysis, consistently demonstrating that the expression of KIAA1429 was dramatically upregulated in HCC tissues compared with that in adjacent normal tissues (Fig. 1a)
Scale bars = 100 μm. f and g, Cell apoptosis was measured by FITC-Annexin V and PI staining in SK-Hep1 and HCCLM3 cells transfected with KIAA1429 small interference RNA (siRNA) or the control, followed by flow cytometric analysis. h and i, Transwell invasion assays for SK-Hep1 and HCCLM3 cells transfected with KIAA1429 siRNAs or the control
Summary
N6-methyladenosine (m6A) modification, the most abundant internal methylation of eukaryotic RNA transcripts, is critically implicated in RNA processing. Its function and mechanism in hepatocellular carcinoma (HCC) remain poorly defined. N6-methyladenosine (m6A) modification is the most abundant internal methylation of RNA transcripts in. The formation of m6A methylation is catalyzed by the methyltransferase complex that consist of m6A writers, among which METTL3 (methyltransferase-like 3), METTL14 (methyltransferase-like 14), WTAP (WT1-associated protein) and KIAA1429 (VIRMA, vir-Like m6A methyltransferase associated) play key roles [4]. Mounting evidence has demonstrated that m6A modification exerts significant and comprehensive effects on diverse biological regulatory processes, including transcription splicing, RNA stability, translation efficiency, embryonic stem cell maintenance and specification, cell fate determination, T-cell homeostasis, neuronal functions and sex determination [7,8,9]. The precise functions of KIAA1429 and the underlying regulatory mechanisms in HCC remain poorly understood
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