Evaluating METTL1-mediated m7G tRNA methylation as a novel dependency in alveolar rhadomyosarcoma

Dana-Farber Cancer Inst, Boston MA

Investigators

Abstract

The oncogenic fusion protein PAX3/7-FOXO1 is the major driver of alveolar rhabdomyosarcoma (ARMS) tumorigenesis but is challenging to therapeutically target. Current treatment options for patients with ARMS are limited to cytotoxic chemotherapies. Identifying novel dependencies unique to the PAX3/7-FOXO1 fusion protein may provide new targeted therapeutic avenues for treating ARMS. RNA modifications have garnered recent interest as potential therapeutic targets due to their reversible nature. tRNA modifications, specifically m7G, play direct roles in regulating translation and have been co-opted by oncogenic programs to selectively promote the translation of oncogenic proteins. Our understanding of how m7G tRNA methylation contributes to tumorigenesis is limited. The K00 phase of this proposal will profile the dynamic role of m7G tRNA methylation in ARMS tumorigenesis and unveil novel insights into how this epitranscriptomic mechanism is dysregulated in ARMS. Oncogenic transformation is a dynamic process and m7G tRNA methylation is similarly dynamic in nature. We hypothesize that METTL1, an m7G methyltransferase, is a dependency in ARMS that promotes the selective translation of ARMS-promoting proteins in an m7G-dependent manner. Elucidating the functional relationship between PAX3/7-FOXO1 and METTL1 has yet to be identified but may serve as a previously unidentified therapeutic avenue. We seek to evaluate this relationship and dependency in ARMS tumorigenesis in two aims. In Aim 1, we seek to establish METTL1 as a therapeutic target in ARMS and evaluate the relationship between METTL1 and PAX3/7-FOXO1 using both genetic and chemical approaches in vitro and in vivo. In Aim 2, we will map the METTL1-dependent targets across ARMS tumorigenesis. Current understanding postulates that the cell of origin for ARMS are myoblasts and that myoblasts can undergo oncogenic reprogramming and transform into an ARMS cell. Therefore, we propose to map the changes in METTL1-dependent m7G targets across the transformation continuum from a myoblast to an ARMS cell. We hypothesize that the m7G-dependent targets change dynamically across the transformation from a myoblast to an ARMS cell. Successful completion of the K00 phase of this proposal will uncover novel mechanisms of m7G tRNA methylation and establish METTL1/m7G-dependent targets as potential therapeutic targets and biomarkers of ARMS development. Our proposed work has significant translational implications and may provide expanded insights into ARMS tumorigenesis and lead to the development of targeted treatment options for patients with ARMS. Completion of the K00 phase of this proposal will allow me to develop critical technical and project management skills necessary to establish myself as a competitive candidate for a successful independent research career in cancer biology.