PROJECT SUMMARY Lung cancer is the most lethal of any of the common cancers. Targeted therapy has a demonstrated benefit in the treatment of lung cancer so identifying novel druggable pathways is a priority. Glutathione S- transferase P1 (GSTP1) is an enzyme that catalyzes the post-translational modification, protein S- glutathionylation. Our preliminary data indicate that 1) GSTP1 over-expression and increased protein S- glutathionylation occurs in approximately 40% of human resected lung adenocarcinomas and is associated with a worse prognosis for early lung cancers; 2) GSTP1-induced S-glutathionylation is important for glycolysis and tumorigenesis in our models of lung adenocarcinoma, and pharmacological GSTP1 inhibition results in decreased tumor formation; and 3) GSTP1-induced S-glutathionylation controls pyruvate kinase M2 (PKM2) conformation. GSTP1 expression is strongly associated with a worse prognosis with a potential ability to identify high-risk individuals who may benefit from targeted treatment strategies. TLK199 is an orally available agent and has an excellent safety profile in Phase II trials (for hematologic cancers). This proposal will focus on addressing the mechanisms of GSTP1-induced S-glutathionylation and its role in tumorigenesis and evaluating the potential for GSTP1 targeted therapies. The hypothesis: S- glutathionylation (notably of PKM2) driven by GSTP1 is important in increasing glycolysis during lung tumorigenesis. Ways to attenuate or reverse S-glutathionylation are thus anticipated to decrease glycolysis and to disrupt tumor cell growth and will be tested in 3 specific aims. In Aim 1 we will determine the impact of inhibition of S-glutathionylation or its reversal on KRASG12D-induced tumorigenesis in an inducible lung cancer mouse model and evaluate the effect of TLK199 on tumor development and growth. This system will also allow us to identify further downstream metabolic effects and targets of GSTP1-induced protein S- glutathionylation. Aim 2 will address the importance of pyruvate kinase M2 in KRASG12D-induced tumorigenesis and investigate the impact of GSTP-linked PKM2 glutathionylation. The goal of Aim 3 is to evaluate GSTP1, overall S-glutathionylation and PKM2 in adenocarcinoma and in primary adenocarcinoma-generated patient-derived tumor xenograft (PDX) mice. We will establish PDX mice from lung cancer biopsies from our actively enrolling lung cancer study at the University of Vermont and the effects of pharmacological inhibition of GSTP on primary tumor cell and PDX mice will be evaluated. Completion of the Aims of this proposed work may prove foundational for clinical investigation of the GSTP1 inhibitor TLK199 for treatment of lung cancer.