IGF2 mRNA binding protein 3 (IMP3) promotes glioma cell migration by enhancing the translation of RELA/p65

Abstract

The diffusely infiltrative nature of glioblastoma (GBM) makes them highly recurrent. IGF2 mRNA-binding protein 3 (IMP3), a GBM upregulated RNA binding protein, promotes glioma cell migration. An integrative bioinformatics analysis identified p65 (RELA), a subunit of NF-κB heterodimer as a target and an important mediator of IMP3 promoted glioma cell migration. IMP3 increased p65 protein levels without any change in p65 transcript levels, but promoted its polysome association. RIP-PCR demonstrated the binding of IMP3 to p65 transcript. UV crosslinking experiments with in vitro transcribed RNA confirmed the specific and direct binding of IMP3 to sites on p65 3′UTR. Further, IMP3 induced luciferase activity from p65 3′UTR reporter carrying wild type sites but not mutated sites. Exogenous overexpression of p65 from a 3′UTR-less construct rescued the reduced migration of glioma cells in IMP3 silenced condition. In addition, IMP3 silencing inhibited glioma stem-like cell maintenance and migration. The exogenous overexpression of 3′UTR-less p65 significantly alleviated the inhibition of neurosphere formation observed in IMP3 silenced glioma stem-like cells. Further, we show that IMP3 is transcriptionally activated by NF-κB pathway indicating the presence of a positive feedback loop between IMP3 and p65. This study establishes p65 as a novel target of IMP3 in increasing glioma cell migration and underscores the significance of IMP3-p65 feedback loop for therapeutic targeting in GBM.

Carnosol controls the human glioblastoma stemness features through the epithelial-mesenchymal transition modulation and the induction of cancer stem cell apoptosis

“…The formation of neurospheres in U87MG, U343MG and T98G cell cultures in vitro was induced by a specific neural stem-cell (NSC) medium 53 , 54 . Consistent with literature data 53 – 56 , the spheres obtained using U87MG, U343MG and T98G (Fig. S1 , Figs 2 and 3 ) included significantly higher levels of the stem cell markers CD133, Nanog, Nestin, OLIG2, CD44, SOX2, Oct4, BMI1 and STAT3 a smaller percentage of GFAP compared with the adherent counterpart (Figs S1 , 2 and 3 ).…”

IGF2BP3 From Physiology to Cancer: Novel Discoveries, Unsolved Issues, and Future Perspectives

“…of aberrantly expressed transcription factors. Chromatin immunoprecipitation (ChIP) assays (Box 1) confirmed the direct binding of the transcription factors Nanog and NF-κB to the IGF2BP3 promoter, thus sustaining its expression in tumor cells and favoring the stemness and migration properties, respectively (Chen et al, 2013;Bhargava et al, 2017). In triple-negative breast cancer cells, EGFR signaling regulates IGF2BP3 transcription since the IGF2BP3 promoter activity decreased after MEK1/2 signaling inhibition downstream of EGFR (Samanta et al, 2012).…”

The Emerging Roles of RNA Modifications in Glioblastoma

“…In addition, IGF2BP3 promotes cell proliferation, anchorage-independent growth, invasion, and chemoresistance via activating PI3K/MAPK pathways by binding to the 5 -UTR of IGF-2 mRNA to activate its translation [97]. IGF2BP3 also stimulates glioma cell migration by enhancing the translation of p65 (RELA), a subunit of nuclear factor kappa-B (NF-κB) heterodimer, which can also in turn transcriptionally activates IGF2BP3 to form a feedback loop [101]. eIF3 Family eIF3a/b/h, also function as m 6 A readers, and can directly, physically and functionally interact with METTL3, thereby enhancing translation, and the formation of densely packed polyribosomes through recognizing m 6 A modification at the 5 UTR of mRNA [102][103][104].…”