The IRX1/HOXA connection: insights into a novel t(4;11)-specific cancer mechanism

Introduction: MLL fusion proteins cause the ectopic transcriptional activation of specific HOXA genes. In case of t(4;11) leukemia, this picture becomes challenged, because they separate for yet unknown reasons into “HOXA hi” and “HOXA lo” patients. HOXA lo patients overexpress the homeobox gene IRX1. This was associated with an even higher relapse rate and worse outcome. Methods: We used transient and stable transfection experiments, gene expression profiling experiments, chromatin-immunoprecipitation experiments, Western blots and diverse PCR techniques. Results: We demonstrate that IRX1 proteins interact with…