Daniel Schramek
University of Toronto
Canada
Title: Rapid RNAi and CRISPR based direct in vivo screening to systematically reveal novel squamous cell carcinoma genes
Biography
Biography: Daniel Schramek
Abstract
Mining the wealth of genomic data for personalized cancer therapies poses one of the biggest challenges for translational cancer research today and is predicated on weeding out ‘bystander’ mutation and identifying the ‘driver’ mutations and pathways responsible for initiating tumorigenesis and metastasis. We thus developed a novel RNAi methodology that allows us to simultaneously screen hundreds of putative human cancer genes directly in vivo using various mouse models of cancer. Importantly, this method tests gene function within the native tissue architecture, stromal cues and immune system. First, we focused on Head & Neck squamous cell carcinomas (HNSCCs), which represent the 6th most common cancer with a mortality >50%. Using ultrasound-guided in utero injections of lentiviral particles, we selectively delivered shRNAs to the single-layered surface ectoderm of living E9.5 mouse embryos, where stem cells stably incorporate and propagate the desired genetic alterations (RNAi) into adulthood in a mosaic fashion. This allowed us to identified seven novel tumor suppressors including Myh9, which encodes non-muscle myosin IIA. Mechanistically, we uncovered that myosin IIA’s function is manifested not only in conventional actin-related processes but also in regulating p53 activation. Clinically, low Myh9 expression stratifies HNSCCs patients with poorest survival. We have now expanded our technology to various other epithelial cancer models, included CRISPR-mediated gene-editing and started with negative screening to elucidate physiological regulators of oncogenic growth further highlighting the utility of direct in vivo screening to integrate human cancer genomics and mouse modeling for rapid and systematic discovery of cancer driver mutations and novel cancer vulnerabilities.