RNA-binding protein FXR1 drives cMYC translation by recruiting eIF4F complex to the translation start site

Abstract

SUMMARY Fragile X-related protein-1 (FXR1) gene is highly amplified in patients with ovarian cancer, and this amplification is associated with increased expression of both FXR1 mRNA and protein. FXR1 expression directly associates with the survival and proliferation of cancer cells. Surface sensing of translation (SUnSET) assay demonstrates that FXR1 enhances the overall translation in cancer cells. Reverse-phase protein array (RPPA) reveals that cMYC is the key target of FXR1. Mechanistically, FXR1 binds to the AU-rich elements (ARE) present within the 3′ untranslated region (3′UTR) of cMYC and stabilizes its expression. In addition, the RGG domain in FXR1 interacts with eIF4A1 and eIF4E proteins. These two interactions of FXR1 result in the circularization of cMYC mRNA and facilitate the recruitment of eukaryotic translation initiation factors to the translation start site. In brief, we uncover a mechanism by which FXR1 promotes cMYC levels in cancer cells.

Patient-Derived Ovarian Cancer Spheroids Rely on PI3K-AKT Signaling Addiction for Cancer Stemness and Chemoresistance

“…Chromosomal abnormalities are common phenomena in development and progression of many human cancers including ovarian carcinoma [ 24 ]. Previously, we have demonstrated that several genes including both protein coding and non-coding genes are aberrantly expressed due to copy number gain in ovarian cancer and in breast cancer [ 17 , 24 , 25 , 26 , 27 , 28 ]. Moreover, chromosomal abnormalities in 1q21 such as amplifications, rearrangements, and translocations, have been reported in several hematological malignancies and solid tumors including endometroid ovarian carcinoma [ 29 , 30 , 31 ].…”

Optimized proximity ligation assay (PLA) for detection of RNA-protein complex interactions in cell lines

“…Along with this assay, we also included the description and tips for both image analysis and quantification of proximal binding sites of FXR1 and its target mRNA by counting of dots representing PLA signal by using image J software. Recently, we have published our enhanced PLA procedure to detect interaction between AU-rich elements present within the 3′UTR region of MYC mRNA and FXR1 protein at the single-cell level in ovarian cancer cell lines ( George et al, 2021 ). In principle, this protocol can be extended to implement the detection of the mRNA-protein as well as protein-protein interaction in a variety of cells.…”

“…This approach will identify several potential binding sites within mRNA. It is highly recommended to perform an RNA electrophoretic mobility shift assay (REMSA) to confirm if the identified sequences exhibit binding affinity with a specific RBP ( George et al, 2021 ).…”

“…This protocol will be particularly useful for studying the proximal interactions between RNA binding proteins (RBPs) and their target mRNAs in cells. For complete details on the use and execution of this protocol, please refer to George et al (2021) .…”

“…For complete details on the use and execution of this protocol, please refer to George et al (2021) .…”