The oncofusion protein FUS-ERG targets key hematopoietic regulators and modulates the all-trans retinoic acid signaling pathway in t(16;21) acute myeloid leukemia

Fusion proteins involving the ETS factor ERG have been associated with multiple cancers such as Ewing's sarcoma and prostate cancer. In acute myeloid leukemias harboring t(16;21) another ERG fusion protein is expressed, FUS-ERG. Here, we found that this FUS-ERG oncofusion protein acts in the context of a heptad of proteins (ERG, FLI1, GATA2, LYL1, LNMO2, RUNX1 and TAL1) central to proper expression of genes involved in maintaining a stem cell hematopoietic phenotype. Moreover, in t(16;21) FUS-ERG co-occupies genomic regions bound by the nuclear receptor heterodimer RXR-RARA inhibiting target gene expression and interfering with hematopoietic differentiation. All-Trans Retinoic Acid treatment of t(16;21) cells as well as FUS-ERG knock down alleviate the myeloid differentiation block. Together, the results suggest that FUS-ERG acts as a transcriptional repressor of the retinoic acid signaling pathway.