The DDX39B/FUT3/TGFβR-I Axis Promotes Tumor Metastasis and EMT in Colorectal Cancer

Abstract

Background: DDX39B is a member of the DEAD box (DDX) RNA helicase family required for nearly all cellular RNA metabolism processes. The exact role and potential molecular mechanism of DDX39B in the progression of human colorectal cancer (CRC) remain to be investigated. Methods: Western blotting and quantitative real-time PCR (qRT-PCR) were conducted to detect the expression of DDX39B in CRC tissues and cell lines. Transwell and wound healing assays were conducted to assess the migration and invasion ability of CRC cells with DDX39B overexpressed or silencing. Orthotopic transplantation model of nude mice was performed to validate CRC metastasis in vivo. RNA sequencing (RNA-seq) and RNA binding protein immunoprecipitation (RIP) assay verified the direct regulation of DDX39B on the splicing and nuclear export of FUT3 mRNA, cytoplasmic and nuclear RNA isolation confirmed the nuclear export effect of DDX39B on FUT3. qRT-PCR was conducted to quantify FUT3 splicing variants. Lectin blotting was conducted to evaluate the fucosylation level of TGFβR-I.Results: In the present study, we demonstrate that DDX39B expression was higher in CRC tissues than in adjacent normal tissues. Gain- and loss- of- function assays revealed that DDX39B facilitated the metastasis of CRC in vivo and in vitro. Mechanistically, RNA-seq and RIP showed that DDX39B upregulated FUT3 expression by binding the first exon of FUT3 mRNA, which promote the mRNA splicing and export of FUT3. RNA-seq results and qRT-PCR showed that overexpression of DDX39B may favor the longer FUT3 mRNA products that contain the complete and longer exon 2, suggesting an alternative splicing of FUT3. Upregulation of FUT3 accelerated the fucosylation of TGFβR-I, thus activating the TGFβ/SMAD signaling pathway, eventually driving the epithelial-mesenchymal transition (EMT) program and contributing to CRC progression. Conclusions: Our finding demonstrated for the first time that the DDX39B/FUT3/TGFβR-I axis promotes the progression of CRC. These findings not only provide new insight into the role of DDX39B in mRNA splicing and export and tumorigenesis, but also shed light on the effect of aberrant fucosylation on CRC progression.

FUT7 Promotes the Epithelial–Mesenchymal Transition and Immune Infiltration in Bladder Urothelial Carcinoma

“…38 It is a complicated pathological process that involves multiple steps, including epithelial to mesenchymal transition, in which cancer cells transit between epithelial and mesenchymal states that facilitating cell dissemination. 39 Our results demonstrated that FUT7 siRNA inhibited the migration, invasion, and EMT of bladder cancer cells, while FUT7 cDNA promoted these cell behaviors ( Figures 2 and 3 ). Overall, our study provided novel and valuable insights into FUT7 as a diagnostic biomarker, prognosis predictor, and therapeutic target for BLCA.…”