Therapeutic targeting for translocation renal cell carcinoma - SUMMARY Translocation Renal Cell Carcinoma (tRCC) represents a rare subtype of kidney cancer associated with aggressive behavior and poor clinical outcome. The prevalence of this disease is high in pediatric kidney cancer, representing 20-40% of total cases of RCC. Noteworthy, the true incidence of this disease in adults is likely underestimated, as a significant number of patients undergoes histological misclassification. TRCC is characterized by gene fusions resulting from chromosomal rearrangement involving TFE3 (Xp11.2) locus or TFEB (6p21 locus), with various partner genes. Despite the identification of multiple TFE3 gene fusions in tRCC (i.e. SFPQ-TFE3, NONO-TFE3, and PRCC-TFE3) there are no effective targeted therapies for patients with tRCC. In preliminary results supported by the DOD (W81XWH1810586), our group has generated SFPQ- TFE3, NONO-TFE3, and PRCC-TFE3 TFE3-Os and established their oncogenic potential. Knocking down TFE3-wild type or full length (TFE3-wt) inhibited the proliferation of tRCC. By using Fluorescence Resonance Energy Transfer (FRET) microscopy imaging our data suggest that TFE3-Os dimerize TFE3-wt and screened compounds have anti-proliferative effect by inhibiting this protein-protein interaction. Thus, this proposal aims to identify small molecules that selectively bind the leucine zipper domain and disrupt the TFE3-Os/TFE3 interaction. Our central hypothesis is that TFE3 chimeric proteins (TFE3-Os) play a key biological role in translocation renal cell carcinoma (tRCC) and represent a rational target for therapeutic interventions. Our hypothesis is that inhibiting the protein-protein homo and/or hetero dimerization of TFE3-Os/TFE3-wt may offer a novel therapeutic opportunity. Our central hypothesis aims to accomplish the objectives of this application by pursuing the following specific aims: Aim 1: To optimize tool compounds and to identify new small molecule inhibitors targeting TFE3-O dimerization. Aim 2: To test the biological and antitumor effects of new small molecule inhibitors targeting TFE3-O dimerization. Aim 1 proposes to optimize lead compound recently identified in our lab, terfernadine and its metabolite fexofenadine. It will also screen for novel compounds targeting TFE3 dimers with a customized cell-based antiproliferation assay that simultaneously monitors TFE3 dimerization status through FRET. Validated hit molecules comprising synthetically tractable scaffolds will be subject to medicinal chemistry optimization for structure-activity relationship, lipophilicity, oral bioavailability and other essential properties. To accelerate the generation of compounds for biological testing, our aim is to employ computer-aided docking of lead compounds with relevant human TFE3 homology models for focused rational drug design. Aim 2 will utilize our established in vitro models to determine the antitumor effect of the optimized tool compounds identified in Aim 1 which disrupt TFE3-Os protein-protein interaction. This aim will then determine the antitumor effect of the leading compounds, as single agents and in rational combinations.
