Insulin-Like Growth Factor 2 mRNA-Binding Protein 3 is a Novel Post-Transcriptional Regulator of Ewing Sarcoma Malignancy

Abstract

Large-scale sequencing studies have indicated that besides genomic alterations, the posttranscriptional regulation of gene expression or epigenetic mechanisms largely influences the clinical behavior of Ewing sarcoma. We investigated the significance of the RNA-binding protein IGF2BP3 in the regulation of Ewing sarcoma aggressiveness. Explorative study was performed in 14 patients with localized Ewing sarcoma using RNA sequencing. Next, 128 patients with localized Ewing sarcoma were divided into two cohorts. In the training set, 29 Ewing sarcoma samples were analyzed using Affymetrix GeneChip arrays. In the validation set, 99 Ewing sarcoma samples were examined using qRT-PCR. Patient-derived cell lines and experimental models were used for functional studies.Univariate and multivariate analyses indicated as a potent indicator of poor prognosis. Furthermore, mRNA was identified as a novel partner of IGF2BP3. Functional studies indicated IGF2BP3 as an oncogenic driver and mRNA as a sponge that by binding IGF2BP3, partly repressed its functions. The combined evaluation of and could identify different patient outcomes-high and low levels indicated poor survival (25%), whereas low and high levels indicated favorable survival (85.5%). The bromodomain and extraterminal domain inhibitor (BETi) JQ1 decreased IGF2BP3 expression, modified the expression of its validated targets and inhibited the capability of Ewing sarcoma cells to grow under anchorage-independent conditions. The combined assessment of and predicts recurrence in Ewing sarcoma patients. Thus, for patients with high expression of IGF2BP3 and poor probability of survival, the use of BETis should be clinically evaluated. .

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

“…Consistently, as observed in Ewing sarcoma cells, the functions of IGF2BP3 can be limited by the mRNA expression of ABCF1, which is a partner transcript of IGF2BP3. ABCF1 mRNA can associate with IGF2BP3 and limit its interaction with oncogenic target transcripts, thus acting as a sponge to repress the oncogenic function of IGF2BP3 (Mancarella et al, 2018b).…”

“…In addition, IGF2BP3 promotes cell migration. Compared to the phenotype of IGF2BP3-null cells, IGF2BP3-expressing tumor cells display a marked motility-prone phenotype with an adherent shape, cellular extensions, lamellipodia, frequent cellcell adhesion contacts (Vikesaa et al, 2006) and an increased capability to form metastases in vivo (Zhao et al, 2017;Mancarella et al, 2018b). Accordingly, different mediators of cell migration/invasion and cell adhesion have been reported as IGF2BP3 mRNA targets in different tumor types.…”

“…The combined evaluation of IGF2BP3 and the proapoptotic protein BCL2 was found to be particularly effective for diagnosis in squamous cell carcinoma (Richey et al, 2018). In hepatocellular carcinoma, the copresence of IGF2BP3 and its target CD44 is correlated with advanced tumor stage/grade and metastasis (Wachter et al, 2012;Hu et al, 2014), while in Ewing sarcoma patients, contemporary high expression of IGF2BP3 and low expression of its counteracting partner ABCF1 is correlated with a particularly poor outcome (Mancarella et al, 2018b). In addition, the circulating IGF2BP3 protein levels, recently detected in serum from prostate cancer and renal cell carcinoma patients, were found to be associated with a significantly higher risk of cancer-specific death or relapse (Szarvas et al, 2014;Tschirdewahn et al, 2019).…”

“…plants, has been demonstrated to inhibit IGF2BP3 expression and reduce the growth of hepatocellular carcinoma cells (Li et al, 2015). In addition, inhibitors of bromodomain and extraterminal domain (BET) proteins, such as JQ1 or iBET, have been found to downregulate IGF2BP3 expression and its targets in Ewing sarcoma and B cell acute lymphoblastic leukemia, consequently attenuating tumor growth (Palanichamy et al, 2016;Elagib et al, 2017;Mancarella et al, 2018b). Considering that clinical trials using BET inhibitors have been performed in hematological and solid tumors with an observed manageable toxicity (Amorim et al, 2016;Berthon et al, 2016), these agents may represent a concrete treatment option for patients with high levels of IGF2BP3 (Mancarella and Scotlandi, 2018;Mancarella et al, 2018b).…”

Insulin-Like Growth Factor 2 mRNA-Binding Protein 3 Modulates Aggressiveness of Ewing Sarcoma by Regulating the CD164-CXCR4 Axis

“…We have recently identified insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) as a major determinant of EWS aggressiveness (20,21). IGF2BP3 has a critical role in modulating multiple mRNAs, thereby regulating tumor initiation and progression (22).…”