YTHDF2 mediates the mRNA degradation of the tumor suppressors to induce AKT phosphorylation in N6-methyladenosine-dependent way in prostate cancer

Abstract

Background N6-methyladenosine (m6A) is the most abundant modification in mRNA of humans. Emerging evidence has supported the fact that m6A is comprehensively involved in various diseases especially cancers. As a crucial reader, YTHDF2 usually mediates the degradation of m6A-modified mRNAs in m6A-dependent way. However, the function and mechanisms of m6A especially YTHDF2 in prostate cancer (PCa) still remain elusive. Methods To investigate the functions and mechanisms of YTHDF2 in PCa, in vitro, in vivo biofunctional assays and epigenetics experiments were performed. Endogenous expression silencing of YTHDF2 and METTL3 was established with lentivirus-based shRNA technique. Colony formation, flow cytometry and trans-well assays were performed for cell function identifications. Subcutaneous xenografts and metastatic mice models were combined with in vivo imaging system to investigate the phenotypes when knocking down YTHDF2 and METTL3. m6A RNA immunoprecipitation (MeRIP) sequencing, mRNA sequencing, RIP-RT-qPCR and bioinformatics analysis were mainly used to screen and validate the direct common targets of YTHDF2 and METTL3. In addition, TCGA database was also used to analyze the expression pattern of YTHDF2, METTL3 and the common target LHPP in PCa, and their correlation with clinical prognosis. Results The upregulated YTHDF2 and METTL3 in PCa predicted a worse overall survival rate. Knocking down YTHDF2 or METTL3 markedly inhibited the proliferation and migration of PCa in vivo and in vitro. LHPP and NKX3–1 were identified as the direct targets of both YTHDF2 and METTL3. YTHDF2 directly bound to the m6A modification sites of LHPP and NKX3–1 to mediate the mRNA degradation. Knock-down of YTHDF2 or METTL3 significantly induced the expression of LHPP and NKX3–1 at both mRNA and protein level with inhibited phosphorylated AKT. Overexpression of LHPP and NKX3–1 presented the consistent phenotypes and AKT phosphorylation inhibition with knock-down of YTHDF2 or METTL3. Phosphorylated AKT was consequently confirmed as the downstream of METTL3/YTHDF2/LHPP/NKX3–1 to induce tumor proliferation and migration. Conclusion We propose a novel regulatory mechanism in which YTHDF2 mediates the mRNA degradation of the tumor suppressors LHPP and NKX3–1 in m6A-dependent way to regulate AKT phosphorylation-induced tumor progression in prostate cancer. We hope our findings may provide new concepts of PCa biology.

Novel prognostic implications of YTH domain family 2 in resected hepatocellular carcinoma

“…In another cohort in the TCGA RNA-sequence dataset, however, the expression of YTHDF1 was found to be significantly higher in HCC tissues, and YTHDF2 was significantly lower in HCC tissues. Li et al reported that upregulation of YTHDF2 was observed in TCGA prostate cancer tissues compared with normal controls ( 16 ). Bai et al also reported that YTHDF1 is significantly upregulated in tumour compared with adjacent normal tissues in colorectal cancer ( 17 ).…”

Main N6-Methyladenosine Readers: YTH Family Proteins in Cancers

“…MiR-493-3p was identified to be an upstream factor of YTHDF2, which suppressed prostate cancer by targeting YTHDF2 (88). Another study had the similar results, YTHDF2 mediated the degradation of tumor suppressors LHPP and NKX3-1 mRNA and indirectly induced AKT phosphorylation to promote prostate cancer progression in an m6A-dependent manner (75). Above results suggest that YTHDF2 acts as an oncogene in prostate cancer and YTHDF2 is expected to be a potential biomarker for diagnosis or targeted therapy of prostate cancer.…”

Linking the YTH domain to cancer: the importance of YTH family proteins in epigenetics

“…YTHDF2 promotes the proliferation and inhibits the migration and invasion as well as EMT of pancreatic cancer cells, probably through YAP signaling, although the exact mechanism remains to be clarified 111 . The oncogenicity of YTHDF2 was revealed in prostate cancer, and YTHDF2 mediates the degradation of LHPP and NKX3-1 to induce the phosphorylation of AKT 112 . In glioblastoma, in contrast to its proposed role, YTHDF2 was shown to stabilize MYC and VEGFA to maintain the oncogenic phenotype of glioblastoma stem cells 113 .…”