Aberrant EZHIP Expression Drives Tumorigenesis in Osteosarcoma [RNA-Seq]

Osteosarcomas (OS) are aggressive bone tumors characterized by extensive structural variation, and rare recurrent oncogenic driver mutations. Here, we identify ectopic expression of the oncohistone-mimic EZHIP in more than 20% of patients, in two independent OS cohorts. Through gain- and loss-of-function experiments, we provide evidence that EZHIP expression is oncogenic, increasing the aggressive features of OS in vitro and in vivo. EZHIP-mediated epigenetic rewiring promotes reactivation of developmental transcriptional programs and stalled differentiation of mesenchymal progenitors, which are skewed towards smooth muscle commitment at the expense of other lineages. Our findings of EZHIP expression as a prevalent driver in OS provide new insights into pathogenic pathways and therapeutic alternatives for this debilitating cancer. Overall design: To investigate the effect of EZHIP expression we established human mesenchymal stem cells (hMSC) and osteosarcoma cell lines (MG63, KHOS) with overexpression of EZHIP. We also used an osteosarcoma cell line with ectopic EZHIP expression (U2OS) to knock out EZHIP. The two osteosarcoma cell lines with EZHIP overexpression were used to create xenograft models. For each cell line and xenograft model the expression profiles were compared between EZHIP expressing and WT/EZHIP knock out.35 samples are provided, including 6 hMSC cell lines, 18 osteosarcoma cell lines and 11 xenograft tumours. 3 replicates per condition