WTAP facilitates progression of hepatocellular carcinoma via m6A-HuR-dependent epigenetic silencing of ETS1

Abstract

Background N6-methyladenosine (m6A) methylation, a well-known modification with new epigenetic functions, has been reported to participate in the tumorigenesis of hepatocellular carcinoma (HCC), providing novel insights into the molecular pathogenesis of this disease. However, as the key component of m6A methylation, Wilms tumor 1-associated protein (WTAP) has not been well studied in HCC. Here we investigated the biological role and underlying mechanism of WTAP in liver cancer. Methods We determined the expression of WTAP and its correlation with clinicopathological features using tissue microarrays and the Cancer Genome Atlas (TCGA) dataset. And we clarified the effects of WTAP on HCC cells using cell proliferation assay, colony formation, Edu assay and subcutaneous xenograft experiments. We then applied RNA sequencing combined with gene expression omnibus (GEO) data to screen candidate targets of WTAP. Finally, we investigated the regulatory mechanism of WTAP in HCC by m6A dot blot assay, methylated RNA immunoprecipitation (MeRIP) assay, dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay and Chromatin immunoprecipitation (ChIP) assay. Results We demonstrated that WTAP was highly expressed in HCC which indicated the poor prognosis, and that WTAP expression served as an independent predictor of HCC survival. Functionally, WTAP promoted the proliferation capability and tumor growth of HCC cells in vitro and in vivo. Furthermore, ETS proto-oncogene 1 (ETS1) was identified as the downstream effector of WTAP. The m6A modification regulated by WTAP led to post-transcriptional suppression of ETS1, with the implication of Hu-Antigen R (HuR) as an RNA stabilizer. Then ETS1 was found to inhibit the progression of HCC and could rescue the phenotype induced by WTAP deficiency. Moreover, WTAP modulated the G2/M phase of HCC cells through a p21/p27-dependent pattern mediated by ETS1. Conclusion We have identified that WTAP is significantly up-regulated in HCC and promotes liver cancer development. WTAP-guided m6A modification contributes to the progression of HCC via the HuR-ETS1-p21/p27 axis. Our study is the first to report that WTAP-mediated m6A methylation has a crucial role in HCC oncogenesis, and highlights WTAP as a potential therapeutic target of HCC treatment. Electronic supplementary material The online version of this article (10.1186/s12943-019-1053-8) contains supplementary material, which is available to authorized users.

Identification of a m6A RNA methylation regulators-based signature for predicting the prognosis of esophageal adenocarcinoma

“…In this present study, we proved that 10 out of 16 m 6 A RNA methylation regulators were highly expressed in EAC. This is consistent with the results from previous studies focusing on gastric carcinoma, lung cancer, HCC and other malignant tumors [36][37][38]. Compared with the expression level in normal tissues, the expression of three genes, HNRNPA2B1, HNRNPC, and YTHDF1, were signi cantly up-regulated in EAC tissues with p<0.001.…”

Functions of N6-methyladenosine and its role in cancer

“…The expression of VIRMA is also higher in HCC tissue, leading to increased cell proliferation and invasion by enhancing m6A modification and inhibiting expression of ID2 mRNA [145]. WTAP is also elevated, resulting in increased cell proliferation and colony formation through facilitating m6A in ETS1 and causing epigenetic silencing of ETS1 [146].…”

The emerging roles of N6-methyladenosine (m6A) deregulation in liver carcinogenesis

“…In fact, high expression of METTL3, YTHDF1 and Snail is correlated with poor prognosis in HCC patients [66]. Similarly, WTAP and KIAA1429, another two components of the m6A "writer" complex, are also upregulated in HCC and correlated with poor patient survival [73,74]. In contrast, Ma et al reported that METTL14 expression was decreased in human HCC and was associated with tumor recurrence.…”