METTL14 gene polymorphisms decrease Wilms tumor susceptibility in Chinese children

Wilms tumor, also known as nephroblastoma, is the most common pediatric kidney cancer [1]. It accounts for over 90% of all the diagnosed kidney tumors in children [2]. The incidence rate of Wilms’ tumor varies geographically [3, 4]. The prevalence of Wilms tumor is about 7 cases per million children in the United States. Wilms tumor is also one of the most common renal tumors in children in China, with an incidence rate of ~ 3.3 per million. Wilms tumors are frequently diagnosed in young children with an average age of 2–3 years [5]. At present, long-term overall survival for the localized Wilms tumors exceeds 90% due to the improved risk stratification-adapted treatment [6]. However, nearly 20% of Wilms tumors are classified into high-risk subtype with frequent metastasis. Patients with high-risk tumors still subject to suboptimal outcomes [7‐9]. Chronic health conditions secondary to intensified therapeutic regimens impact nearly 25% of Wilms tumor survivors [10].

The genetics of Wilms tumor tumorigenesis is complex, with multiple oncogenic drivers identified over the years. The currently known repertoire of oncogenic Wilms tumor driver alterations includes mutations in the WT1, CTNNB1, TP53, AMER1, as well as an abnormality of 11p15 methylation [11‐15]. Apart from these, genetic association analyses in case-control studies also unveiled some Wilms tumor susceptibility loci [16‐19]. Nevertheless, the well-established risk factors for Wilms tumor probably are only the tip of the iceberg. So far, all the known gene mutations can only explain less than 50% of Wilms tumor. Therefore, it is imperative to identify more causative variants to improve the understanding of the genetic susceptibility to Wilms tumor. In addition, detailed genetic information leads to new druggable targets, facilitating the development of more effective treatments for Wilms tumor.

N6-methyladenosine (m⁶A) is the most common internal chemical modification on eukaryotic mRNA [20]. m⁶A is mainly involved in the regulation of splicing, subcellular localization, translation, stability, and degradation of mRNA. m⁶A modulators are mainly classified into methyltransferase (writer), demethylase (eraser), and binding protein (reader). Methyltransferases include METTL3, METTL14, and WTAP, which mainly mediate m⁶A methylation of mRNA adenylate. Demethylases, consisting of FTO and ALKBH5, mainly remove m⁶A modification installed on RNA. Binding proteins include YTHDF1/2/3, YTHDC1/2, IGF2BP1/2/3, and eIF3, which are responsible for recognizing bases modified by m⁶A and regulating downstream pathways [21, 22]. The m⁶A modulator proteins play an important role in the occurrence and development of a variety of tumors [23‐25]. However, research on the expression and function of m⁶A modulator genes in Wilms tumor has not yet been reported. The scarcity of investigation prompted us to contribute to our current report on associations between genetic variability of METTL14 and the risk of Wilms tumor. To this end, a total of five common SNPs in the METTL14 gene were genotyped and tested for their association with Wilms tumor susceptibility.

This is the first genetic epidemiological study on the association of genetic variants in the METTL14 gene and Wilms tumor risk. We found that common variants in the METTL14 gene were significantly associated with susceptibility to this malignancy. This study may contribute to uncovering the underlying biology and genetics of Wilms tumor.

METTL14 is a key component of the m⁶A methyltransferase complex. METTL14 has different roles in different tumors and can be either a cancer promoter or suppressor. Chen et al. [36] identified METTL14 as a tumor suppressor in colorectal cancer. The low METTL14 was significantly associated with poor overall survival. Further functional experiments demonstrated that METTL14 inhibited the progression of colorectal cancer by regulating the production process of m⁶A-dependent precursor miR-375. Ma et al. [37] found that METTL14 was remarkedly downregulated in hepatocellular carcinoma. The reduced METTL14 expression was significantly associated with unfavorable recurrence-free survival and overall survival. The inhibitory role of METTL14 on hepatocellular carcinoma may be partly attributed to its facilitation of the primary miR-126 maturation in a m⁶A-dependent manner. METTL14 exerted an oncogenic role in acute myeloid leukemia via mRNA m⁶A modification [38]. Lang et al. [39] observed that METTL14 was an important driver in EBV-induced oncogenesis. They found that knockdown of METTL14 caused a decreased tumorigenic activity of EBV-transformed cells in the xenograft animal model systems. METTL14 could promote the growth and metastasis of pancreatic cancer by up regulating the m⁶A level of PERP mRNA [40].

Since the function and mechanism of m⁶A modification in mammals have not been studied for a long time, the effect of SNPs of m⁶A modification genes on genetic susceptibility to tumors has been hardly understood. Through adopting a two-stage case-control study, Meng et al. [41] conducted the first study to explore whether m⁶A gene SNPs could predispose to colorectal cancer in the Chinese population. All the five METTL14 gene SNPs (rs115267066, rs167246, rs2029399, rs298981, and rs441216) failed to show impacts on colorectal cancer risk. By enrolling 898 patients with neuroblastoma and 1734 controls, our group found that the METTL14 gene rs298982 G > A and rs62328061 A > G could significantly reduce the risk of neuroblastoma in children, while rs9884978 G > A and rs4834698 T > C could significantly increase the risk of neuroblastoma [28]. Regarding Wilms tumor, no studies investigating the role of METTL14 gene SNPs were available by far.

In the current study, rs1064034 and rs298982 variant alleles were found to protect from developing Wilms tumor. The combination of five protective genotypes led to a 0.69-fold decrease in the risk of developing Wilms tumor in comparison to 0–4 protective genotypes, indicating the stronger effect of the combined SNPs. It is believed that association studies based on haplotypes of multiple SNPs instead of individual SNP remarkedly strengthen the power for mapping and characterizing disease-causing genes [42, 43]. Thus, we examined whether haplotypes of METTL14 gene are associated with Wilms tumor risk. Expectedly, METTL14 gene haplotypes showed a significantly increased protection against Wilms tumor, indicating the synergistic effects of these SNPs. Genetic variation can modulate gene expression, thereby affecting phenotypes and susceptibility to complex diseases such as Wilms tumor. Here we harnessed the GTEx database to evaluate the effect of SNPs rs1064034 and rs298982 on expression and alternative splicing events of genes. We found that rs1064034 and rs298982 were significantly correlated with the expression and splicing of its nearby genes SNHG8 and RP11-384 K6.6. LncRNA SNHG8 acts as a vital role in tumorigenesis [44‐48]. Thus, it is biologically possible that changes of the expression and splicing of SNHG8 and RP11-384 K6.6 caused by SNP rs1064034 and rs298982 may influence Wilms tumor risk (Fig. 3). Our results bring new insights into genetic mechanisms of how METTL14 affects Wilms tumor risk. Our findings identify METTL14 gene SNPs as risk markers in pediatric Wilms tumor. These findings not only show the relationship between some METTL14 gene SNPs and Wilms tumor risk but also can help to improve risk stratification strategies for Wilms tumor patients. In all, in-depth mechanism of how METTL14 SNPs affects Wilms tumor risk by regulating the gene expression and splicing pattern awaits to be elucidated. Potential limitations of our study include relatively small sample size, a lack of independent validation, and failure to incorporate other confounders. We also acknowledged that the conclusion obtained here was limited to Chinese. Cautions should be taken when interpreting this conclusion in other populations.