GSE109677
IGF2BP1 enhances an aggressive tumor cell phenotype by impairing miRNA-directed downregulation of oncogenic factors [HUH-7 small RNA]
The oncofetal IGF2 mRNA binding protein (IGF2BP) family modulates tumor cell properties but IGF2BP paralogue-specific roles remain poorly understood. We demonstrate that phenotypic roles of IGF2BPs vary in a cancer cell-dependent manner. However, only IGF2BP1 shows oncogenic potential in all cancer cells analyzed. Consistently, only IGF2BP1 expression is associated with poor prognosis in ovarian carcinoma and promotes all oncogenic properties analyzed in ovarian cancer-derived tumor cells. Despite a substantial overlap of candidate target mRNAs of IGF2BP paralogues proposed by CLIP analyses, the paralogue-specific depletion of IGF2BPs induces strikingly distinct deregulation of mRNA abundance. Transcripts decreased by IGF2BP1 depletion or knockout are enriched for IGF2BP1- as well as AGO-CLIP hits conserved in distinct cell lines, are prone to targeting by highly abundant miRNAs and comprise significantly longer 3'UTRs. Downregulation of target mRNAs upon IGF2BP1 depletion is abrogated when miRNAs are expressed at low levels or depleted by DICER/DROSHA knockdown. Strikingly, the depletion of all 12 randomly selected miRNA-prone target mRNAs impairs at least one analyzed IGF2BP1-modulated tumor cell property. These findings indicate that IGF2BPs serve distinct roles in cancer-derived cells and suggest that IGF2BP1's main role is the post-transcriptional, miRNome-dependent enhancement of factors promoting oncogenic tumor cell properties. Overall design: small RNA-Seq of HUH-7 cells. One replicate.