In-person Flash Talk & E-Poster Presentation 34th Lorne Cancer Conference 2022

Adaptive mRNA processing pathways reprogram metabolism to limit response to targeted therapy in BRAF mutant melanoma. (#39)

Lorey Smith 1 2 , Tiffany Parmenter 2 , Eric Kusnadi 1 2 , Jian Kang 1 2 , Julie Lorent 3 , David Papadopoli 4 , Claire Martin 2 , Peter Lau 1 2 , Anna Trigos 1 2 , Kaylene Simpson 1 2 , Ola Larsson 3 , Benjamin Blythe 2 , Carleen Cullinane 2 , Vi Wickramesinghe 1 2 , Rick Pearson 1 2 , Grant McArthur 1 2
  1. Sir Peter McCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia
  2. Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
  3. Karolinska Institute, Stockholme, Sweden
  4. McGill University, Montreal, Canada

Despite the success of therapies targeting oncogenes in cancer, clinical outcomes are limited by a residual disease that results in relapse. This residual disease is often characterized by adaptive resistance that occurs via non-genetic mechanisms, and in melanoma involves altered metabolism. To examine how targeted therapy reprograms metabolism in BRAFV600 melanoma cells we employed a genome-wide screen for regulators of glycolysis and identified a role for selective mRNA export, transport and translation. Global poly-ribosome profiling confirmed extensive post-transcriptional reprogramming during the BRAF inhibitor response involving translational regulation and buffering of multiple metabolic pathways. We demonstrate that the lead candidate identified in our screen, the RNA processing kinase UHMK1, selectively associates with mRNA encoding metabolic proteins and regulates their nuclear export during the acute BRAFi response. UHMK1 is recruited to translating ribosomes upon BRAF inhibition and is essential for efficient synthesis of these metabolic proteins. UHMK1 depletion induces cell death by impairing glycolysis and mitochondrial oxidative metabolism, and importantly, genetic inactivation of UHMK1 delays resistance to MAPK pathway targeted therapy in vivo. Our data suggests UHMK1 regulates therapy-induced metabolic plasticity by controlling the abundance of metabolic enzymes through the export and translation of the mRNA that encode them. We propose a model wherein adaptive mRNA trafficking pathways contribute to metabolic plasticity underpinning targeted therapy response, and we suggest inactivation of these pathways may delay development of resistance to targeted therapies.