Poster abstracts
Poster number 109 submitted by Jack Kucinski
Understanding the initial in vivo activities of the fusion-oncogene PAX3-FOXO1
Jack Kucinski (Molecular, Cellular, and Developmental Biology Ph.D. Program, The Ohio State University; Center for Childhood Cancer Research, The Abigail Wexner Research Institute, Nationwide Childrens Hospital), Matthew Cannon (Center for Childhood Cancer Research, The Abigail Wexner Research Institute, Nationwide Childrens Hospital), Katie Silvius (Center for Childhood Cancer Research, The Abigail Wexner Research Institute, Nationwide Childrens Hospital), Benjamin Stanton (Center for Childhood Cancer Research, The Abigail Wexner Research Institute, Nationwide Childrens Hospital; Department of Pediatrics, The Ohio State University College of Medicine), Genevieve Kendall (Center for Childhood Cancer Research, The Abigail Wexner Research Institute, Nationwide Childrens Hospital; Department of Pediatrics, The Ohio State University College of Medicine)
Abstract:
Fusion-positive rhabdomyosarcoma is a devastating and aggressive pediatric cancer with skeletal muscle-like characteristics. PAX3-FOXO1 is its most common and lethal fusion-oncogenic driver, yet despite knowing about it for around 30 years, there are still no targeted therapeutics that significantly improve outcomes. PAX3-FOXO1 arises from a genetic translocation event that fuses the DNA binding domain of PAX3 with the transactivation domain of FOXO1. This chimeric transcription factor has pioneering activity allowing it the unique potential to bind to inaccessible chromatin regions and make them amenable to transcription. However, the mechanisms by which PAX3-FOXO1 generates and maintains a tumorigenic cell fate are still unknown and are technically challenging to study. Here, we utilize zebrafish to characterize these initial activities of the fusion-oncoprotein by directly injecting human PAX3-FOXO1 mRNA into embryos. Upon injection, embryos exhibit arrested development and high levels of lethality, with the vast majority dying within a day. We observe expression of PAX3-FOXO1 peaks at six hours post-fertilization. Through ChIP-seq and RNA-seq experiments at this time point, we find PAX3-FOXO1 directly interacts with DNA and can regulate genes to drive a neural transcriptional profile, like observed in patients. By comparing our datasets from these zebrafish embryos to patient data and our fusion-positive rhabdomyosarcoma zebrafish tumor model, we plan to identify conserved PAX3-FOXO1 mechanisms and targets across different stages of tumorigenesis. Additionally, this model allows for rapid modification to study the mechanism of cooperating factors, which will further elucidate tumorigenic mechanisms. This current study and our model will provide valuable insight into chromatin structure and regulation, which may be broadly applicable across other cancers and development.
Keywords: fusion-oncogene, zebrafish modeling, transcription factor