KIAA1429 contributes to liver cancer progression through N6-methyladenosine-dependent post-transcriptional modification of GATA3

N6-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. Quantitative 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. KIAA1429 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. Our study proposed a complex KIAA1429-GATA3 regulatory model based on m6A modification and provided insights into the epi-transcriptomic dysregulation in hepatocarcinogenesis and metastasis.