Project Summary/Abstract Solute carriers, which include members of the Major Facilitator Superfamily (MFS), comprise a large and understudied group of proteins with roles in diverse biological processes, including metal transport and stress resistance. Using Saccharomyces cerevisiae as a model organism, our previous studies showed that the clinically promising anticancer ruthenium complex KP1019 induces expression of the evolutionarily conserved MFS protein Tpo1. However, the mechanisms driving this induction are unknown. Given that Tpo1, like many other MFS proteins, effluxes a diverse range of toxins from cells, the KP1019 resistance of yeast lacking TPO1 is counterintuitive. Possible explanations for this surprising phenotype include compensatory activation of other drug transporters or perturbation of polyamine homeostasis, which is known to be regulated by Tpo1. To advance our long-term goal of determining how solute carriers, including their regulation, modulate KP1019 tolerance, we will pursue three specific aims focused on identifying the upstream regulators and downstream effectors of the relationship between KP1019 and Tpo1. Specifically, we propose to 1) determine the mechanism(s) and physiological significance of TPO1 induction by KP1019, 2) characterize the KP1019 resistance caused by deletion of TPO1, and 3) discover novel modulators of KP1019 resistance/sensitivity. Deletion of transcription factor genes implicated in our previous studies will enable identification the regulator(s) responsible for drug-dependent induction of KP1019. Transcriptomic analyses will inform hypothesis-driven experiments aimed at determining the roles of compensatory activation of drug efflux and polyamine homeostasis in the KP1019 resistance of yeast lacking TPO1. A quantitative phenomic screen of the yeast deletion collection will aid in discovering new modulators of KP1019 tolerance, enabling establishment of genetic markers that predict patient response to anticancer ruthenium complexes. Furthermore, this project will enhance the research infrastructure at Furman University, creating new opportunities for undergraduates to engage with high throughput techniques paired with hypothesis-driven experiments, a combination that will increase their likelihood of pursuing careers in the biomedical sciences.