FMRP modulates the Wnt signalling pathway in glioblastoma

Abstract

Converging evidence indicates that the Fragile X Messenger Ribonucleoprotein (FMRP), which absent or mutated in Fragile X Syndrome (FXS), plays a role in many types of cancers. However, while FMRP roles in brain development and function have been extensively studied, its involvement in the biology of brain tumors remains largely unexplored. Here we show, in human glioblastoma (GBM) biopsies, that increased expression of FMRP directly correlates with a worse patient outcome. In contrast, reductions in FMRP correlate with a diminished tumor growth and proliferation of human GBM stem-like cells (GSCs) in vitro in a cell culture model and in vivo in mouse brain GSC xenografts. Consistently, increased FMRP levels promote GSC proliferation. To characterize the mechanism(s) by which FMRP regulates GSC proliferation, we performed GSC transcriptome analyses in GSCs expressing high levels of FMRP, and in these GSCs after knockdown of FMRP. We show that the WNT signalling is the most significantly enriched among the published FMRP target genes and genes involved in ASD. Consistently, we find that reductions in FMRP downregulate both the canonical WNT/β-Catenin and the non-canonical WNT-ERK1/2 signalling pathways, reducing the stability of several key transcription factors (i.e. β-Catenin, CREB and ETS1) previously implicated in the modulation of malignant features of glioma cells. Our findings support a key role for FMRP in GBM cancer progression, acting via regulation of WNT signalling.

RETRACTED: A Wnt pathway-associated model and nomogram predict the outcome of GBM patients

“…Posaconazole (POS) inactivated the Wnt/β-catenin signalling pathway to inhibit GBM stem-like cells (GSCs) in GBM [28]. Fragile X Messenger Ribonucleoprotein (FMRP), an alternative RNA binding protein, promotes cell proliferation of GSCs mediated by the Wnt signalling pathway [29]. Overexpression of FMRP contributes to GBM progression by upregulating Wnt/β-catenin and the Wnt-ERK1/2 pathway.…”

Aberrant hyperexpression of the RNA binding protein FMRP in tumors mediates immune evasion

“…To further substantiate the previously reported up-regulation of FMRP in tumors (15)(16)(17)(18)(19), we assessed FMRP expression in human tumor tissue microarrays (TMAs) and in cognate de novo mouse tumors from the pancreas, colon, breast, and melanomas compared with normal tissue. Consistent with the aforementioned studies, FMRP is up-regulated in major subsets of human pancreatic ductal adenocarcinoma (PDAC), colon carcinoma, and triple-negative breast cancer (TNBC) (Fig.…”

“…Aiming to extend upon previous functional studies involving short hairpin RNA (shRNA) KD of FMR1 in cancer cells (15)(16)(17)(18)(19), we used CRISPR-Cas9 technology to genetically delete the FMR1 gene in a series of single-cell cloned mouse cancer cell lines, beginning with the PDAC line 4361.12 (15) and the colon cancer line CT26 (25). For the analyses, we selected two PDAC Fmr1-KO clones and one CT26 Fmr1-KO clone that were devoid in expression of FMRP protein (fig.…”

Age-Dependent Dysregulation of APP in Neuronal and Skin Cells from Fragile X Individuals

“…Protein extracts were separated by 10% or 8% SDS-PAGE and transferred to a PVDF membrane. Membranes were incubated using the following specific antibodies, including mouse anti-puromycin (1:500, DSHB), mouse anti-Vinculin (1:2000, Merck), mouse anti-GAPDH (1:2000, Invitrogen, Thermo Fisher Scientific, Waltham, MA, USA), rabbit anti-APP (1:2000, Merck), rabbit anti-ADAM10 (1:500, Abcam, Cambridge, UK), mouse anti-sAPPα (1:500, IBL America, Minneapolis, MN, USA), rabbit anti-OCT3/4 (1:1000, Santa Cruz Biotechnology, Dallas, TX, USA), mouse anti-MAP2 (1:2000, Merck), mouse anti-Nestin (1:1000 Santa Cruz Biotechnology), mouse anti-SAP97 (1:1000, ENZO Life Sciences, Farmingdale, NY, USA) and rabbit anti-FMRP (1:1000, produced in house PZ1 [52]), HRP-conjugated anti-rabbit and anti-mouse secondary antibodies (1:5000, Cell Signaling Technology, Danvers, MA, USA). Proteins were revealed using an enhanced chemiluminescence kit (Bio-Rad, Hercules, CA, USA) and the imaging system LAS-4000 mini (GE Healthcare, Chicago, IL, USA).…”