Grant: Foundation Grant

Animal Models; Cell Signalling; Cell Stress Including Hypoxia; Childhood Sarcoma; Ewing Tumour; Mechanisms Of Metastasis; Metastasis; Molecular Pathology; Osteosarcoma; Pediatric Brain Tumours

<html> <body> <p>Cancer is the most common cause of non-accidental death in children, and ~20% of patients die of their disease, particularly in high-risk childhood sarcomas, brain tumours, and neuroblastoma. Bold new approaches are needed to find tractable targets for these devastating diseases.<br> <br> Tumour cells are continually exposed to stress including nutrient and O₂ deprivation, oxidative and genotoxic stress, or toxic therapy. While initially restraining tumour growth, each stress is potentially lethal unless tumour cells acutely adapt to it. However, selective pressure can also lead to emergence of stress-adapted clones with aggressive capacity. While stress adaptation is generally attributed to genetic or epigenetic mechanisms, recent work suggests that a major component occurs through acute changes in mRNA translation. As described in this proposal, 3 proteins we study in high-risk pediatric cancers, YB-1, eEF2K, and Hace1, each selectively increase mRNA translation and synthesis of proteins that are critical for stress adaptation. We postulate that these and other acute translation changes facilitate survival under stress, potentially giving rise to clones with acquired resistance to therapy. <i><u>The overarching hypothesis of our work is that acute stress adaptation through altered mRNA translation contributes to tumor cell clonal selection and the emergence of aggressive behavior, including metastatic capacity.</u></i> <br> <br> The goals of our program are to decipher stress-adaptive mechanisms in high-risk pediatric cancer cells through selective mRNA translation, and to test whether inhibiting these mechanisms will reverse stress resistance and restore vulnerability to therapy. This will be tested in the following objectives.<br> <i><u>Objective 1: to further analyze YB-1, eEF2K, and Hace1 signaling in high-risk childhood cancer cells under stress in vitro and in vivo.</u></i> We will dissect biochemical and metabolic pathways mediating YB-1/eEF2K/Hace1 stress resistance <i>in vitro</i>, in order to identify downstream effectors for potential targeting. We will confirm these findings in vivo using tumour xenografts in mouse model systems including renal subcapsular implantation, and in GEMM models as warranted.<br> <i><u>Objective 2: to globally catalogue the &ldquo;translatome&rdquo; of tumour cells under stress +/- inactivation of each of the above pathways.</u></i> We will use RNA sedimentation and ribosome profiling linked to RNAseq, as well as Click-SILAC and pulse-SILAC mass spec, to map the <i>in vitro</i> and <i>in vivo</i> landscape of mRNA translation and protein expression in stressed tumour cells with or without YB-1/eEF2K/Hace1 pathway inactivation. The goal is to identify new therapeutic targets in aggressive pediatric cancers that would otherwise not be apparent using genomic approaches such as RNAseq.<br> <i><u>Objective 3: to test whether inhibiting these mechanisms will reverse stress resistance and restore vulnerability to therapy.</u></i> We will test whether inactivation of selected pathway components blocks stress adaptation and restores sensitivity to therapy. Genetic inactivation of candidates in tumour cell line or primary tumour derived mouse xenografts will be tested for responses to standard of care therapies. For promising and novel druggable targets (e.g. kinases), we will initiate high content screening for small molecule inhibitors.<br> <br> Moreover, this initiative will include a comprehensive mentorship and training program in pediatric oncology research to attract highly qualified trainees into this important field.<br> </p> </body> </html>