N6-methyladenosine modification of ITGA6 mRNA promotes the development and progression of bladder cancer

Background: Accumulating evidence has revealed the critical roles of N-6-methyladenosine (m(6)A) modification of mRNA in various cancers. However, the biological function and regulation of m(6)A in bladder cancer (BC) are not yet fully understood. Methods: We performed cell phenotype analysis and established in vivo mouse xenograft models to assess the effects of m(6)A-modified ITGA6 on BC growth and progression. Methylated RNA immunoprecipitation (MeRIP), RNA immunoprecipitation and luciferase reporter and mutagenesis assays were used to define the mechanism of m(6)A-modified ITGA6. Immunohistochemical analysis was performed to assess the correlation between METTL3 and ITGA6 expression in bladder cancer patients. Findings: We show that the m(6)A writer METTL3 and eraser ALKBH5 altered cell adhesion by regulating ITGA6 expression in bladder cancer cells. Moreover, upregulation of ITGA6 is correlated with the increase in METTL3 expression in human BC tissues, and higher expression of ITGA6 in patients indicates a lower survival rate. Mechanistically, m(6)A is highly enriched within the ITGA6 transcripts, and increased m(6)A methylations of the ITGA6 mRNA 3'UTR promotes the translation of ITGA6 mRNA via binding of the m(6)A readers YTHDF1 and YTHDF3. Inhibition of ITGA6 results in decreased growth and progression of bladder cancer cells in vitro and in vivo. Furthermore, overexpression of ITGA6 inMETTL3-depleted cells partially restores the BC adhesion, migration and invasion phenotypes. Interpretation: Our results demonstrate an oncogenic role of m(6)A-modified ITGA6 and show its regulatory mechanisms in BC development and progression, thus identifying a potential therapeutic target for BC. Fund: This work was supported by National Natural Science Foundation of China (81772699, 81472999). (c) 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).