Ferroptosis in drug resistant glioma

Project Abstract Cancer drug resistance is the last frontier in extending patient overall survival, especially in the deadly brain tumor – glioblastoma (GBM). GBM currently has one standard of care chemotherapeutic agent – temozolomide (TMZ) – which extends median overall survival to ~14-16 months. However, TMZ resistance is

rapid and uniformly fatal. Yet, because there are some long-term responders (~5% at 5-years), almost all newly diagnosed GBMs will receive TMZ, making TMZ-resistance a major clinical unmet need, and the focus of my previous, current, and future work. The central goal of my current work is to better understand the distinct

changes in the metabolic states between TMZ-Sensitive (TMZ-S) and -Resistant (TMZ-R) disease, allowing for the discovery of therapeutically targetable vulnerabilities. To this end, I have found that TMZ-R cells have a greater dependence on cystine import, increase of intracellular iron, and a maintained oxidative state that primes

these TMZ-R models for cyst(e)ine depletion-induced ferroptosis with a known neuroprotective agent – ebselen. I further show that this form of ferroptosis – or iron-dependent cell death – could be induced by the selenium in ebselen or TMZ-Selenium but not a TMZ-Sulfur analog in TMZ-R cells, which will no longer have a response to

TMZ alone. Therefore, the objective of this project is to meticulously characterize this cyst(e)ine depletion- induced ferroptosis phenotype in TMZ-R models where it will both help in our understanding of TMZ-R GBM and develop a framework where small molecule selenium-containing compounds could be of use in other diseases.

To accomplish this goal, I will take full advantage of my excellent mentoring/advisory committee as well as the exceptional resources and training environment available to me at Northwestern University. The expected outcomes of this project include a thorough understanding of the metabolic landscape and changes between

both TMZ-S and -R models, as well as shifts post cyst(e)ine depletion-induced ferroptosis (Aim 1). A characterization and validation of the protein players that are necessary to mediate cyst(e)ine depletion-induced ferroptosis in TMZ-R models, as well as how the increased oxidative state in TMZ-R may affect enzymatic active

site status that would not be discovered via sequencing methods but is essential for protein activity (Aim 2). Finally, the mechanistic knowledge gained from a meticulous understanding of both the metabolic readouts and proteomic players will allow for a smarter animal model design to answer and/or confirm the findings in Aim 1 &

2 (Aim 3). As I already have a strong background in RNA biology/splicing and DNA damage/structure in TMZ-R disease, this proposal will strengthen my knowledge in the metabolic differences and learn proteomic and metabolic techniques. In this way, I will have a well-rounded understanding of TMZ-R disease which will help me

to design smarter and more complete studies in the future when I run my own independent lab.