Abstract PR004: Comparative genomic analysis of novel translocation renal cell carcinoma model reveals molecular mechanisms of disease progression and therapeutic opportunities

Abstract

Introduction. Translocation Renal Cell Carcinoma (tRCC) is a distinct and aggressive molecular subtype of kidney cancer unusually prevalent in children and adolescents. tRCC has a poor prognosis with no specific therapies and is incurable in the metastatic setting. tRCC is characterized by chromosomal translocations involving three out of the four Microphthalmia (MiT) family transcription factors, TFE3, TFE3, and MITF. The most commonly involved gene is TFE3, which most often fuses with ASPSCR1. However, the molecular mechanisms by which ASPSCR1-TFE3 (and more broadly MiT/TFE fusion proteins) dictates tRCC tumorigenesis remain unclear and advances are hampered by the paucity of animal models. Herein, we sought to model tRCC and performed integrative genomic analyses to dissect molecular mechanisms underpinning tRCC tumorigenesis with the goal of translating this knowledge into therapeutic opportunities. Methods. We conditionally expressed a human ASPSCR1-TFE3 fusion in the Pax8 and Sglt2 lineages and performed phenotypic analyses as well as WES and RNAseq of emerging tRCC tumors. Similar genomic analyses of a human tRCC cohort were performed. The mutational landscape, cooperating pathways, and potential therapeutic targets were identified through comparative genomic and transcriptomic analyses. Emerging hypotheses were tested through in vitro and in vivo assays. Results. We show that human ASPSCR1-TFE3 driven by Pax8-Cre, a credentialled RCC driver, disrupted nephron development causing neonatal death, whilst Sglt2-Cre resulted in tRCC with complete penetrance and short latency. In both models, ASPSCR1-TFE3 induced characteristic morphological changes, loss of epithelial markers, and an EMT program, but only in the Sglt2-Cre model was proliferation observed. Given that Pax8-Cre, but not Sglt2-Cre¸ induce clear cell RCC (ccRCC), these data show that tRCC and ccRCC originate from different cell types. Comparative murine/human genomic analyses show that tumorigenesis by MiT/TFE fusion proteins is broadly cooperative (i.e. p53, ATM/ATR, Fanconi anemia, SWI/SNF, Hippo, and Wnt). Gene expression and functional studies implicate EPHA5 as well as Met/Ret in tRCC tumorigenesis. Antitumor/antiproliferative activity was observed with the therapeutic targeting of these pathways. Conclusion. This study provides insight into the tRCC mutational landscape, the cell of origin, and MiT/TFE-driven transcriptional programs offering several avenues for therapeutic development. Citation Format: Gopinath Prakasam, Akhilesh Mishra, Alana Christie, Jeffrey Miyata, Vanina T. Tcheuyap, Hui Ye, Quyen N. Do, Kevin B. Jones, Mai-Carmen Requena-Komuro, Ivan Pedrosa, Dinesh Rakheja, Payal Kapur, James Brugarolas. Comparative genomic analysis of novel translocation renal cell carcinoma model reveals molecular mechanisms of disease progression and therapeutic opportunities [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr PR004.