IDDF2019-ABS-0290 IGF2BP2 facilitates tumor progression via an m6A-dependent mechanism in colorectal carcinoma

Abstract

Background RNA N6-methyladenosine (m6A) is an emerging regulatory mechanism for gene expression and participates in tumor progression in several cancer types. M6A ‘readers’ were reported to be involved in controlling the fate of mRNA, and insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) was reported to be associated with methylated mRNA stability and promote tumor progress However, its role in colorectal carcinoma (CRC) and its target m6A-specific target genes remains unexplored. Methods Western blot, real-time quantitative PCR and immunohistochemical (IHC) analysis were used to detect IGF2BP2 expression in cell lines and patient‘s tissues. The MTS assay, migration assay, sphere formation assay was performed to detect the function of IGF2BP2. Cell-based xenograft model and PDX model revealed the clinical benefits of target IGF2BP2 in vivo. RNA immunoprecipitation (RIP) sequence was used to screen the target genes of IGF2BP2 and RNA pull-down assay was used to verify the direct binding of IGF2BP2 and targets genes. Results IGF2BP2 was significantly upregulated in human CRC tumor tissues and CRC cell lines and high expression of IGF2BP2 was associated with poor prognosis of CRC patients. Knockdown of IGF2BP2 in CRC cell lines drastically suppressed cellular proliferation and stemness phenotype in vitro. IGF2BP2 inhibition suppresses CRC tumorigenesis and metastasis in both cell models and PDX models in vivo. RIP-seq analysis and RIP-qPCR revealed that SOX2 mRNA was the potential target gene of IGF2BP2. RNA pull-down assay showed the direct binding of IGF2BP2 and SOX2 transcripts which could be impaired by mutating m6a site of SOX2 transcripts. After IGF2BP2 inhibition, the RNA and protein level of SOX2 were downregulated due to the half-life of SOX2 mRNA decreased. Moreover, the downstream genes of SOX2 showed a positive correlation with IGF2BP2 expression in CRC patients. Conclusions In summary, we demonstrated that IGF2BP2 was frequently upregulated in human CRC and contributing to CRC malignancy. IGF2BP2 maintained methylated SOX2 mRNA stability to facilitate cellular stemness features through the m6A-dependent mechanism. Thus, our findings reveal an important role of IGF2BP2 and provide a potential target of treatment in colorectal carcinoma.