Abstract 2575: A multi-omic screening approach identifies the E3-ubiquitin ligase DCAF13 as a novel vulnerability in lung adenocarcinoma

Abstract Lung adenocarcinoma (LuAD) is the most prevalent subtype of lung cancer but despite advances in targeted therapy approaches, LuAD patients still have a 5-year survival rate of less than 15%. This is largely owed to a high variability in cancer driver mutations, with only around 25% of patients being eligible for targeted therapy, highlighting the need for therapy approaches beyond the level of genetic modifications. In order to determine novel vulnerabilities of LuAD, we performed a CRISPR/Cas9-based genomic screen with a pooled sgRNA library targeting genes of the ubiquitin system. The screen identified the poorly characterized E3-ubiquitin ligase DCAF13 as an essential gene for LuAD cell survival. Data mining of LuAD patient data revealed that DCAF13 is significantly overexpressed in tumor versus normal tissue and that high DCAF13 expression correlates with adverse overall survival and progression free survival. Mechanistically, DCAF13 depletion leads to a decrease in cell proliferation and subsequent cell death, which can be rescued by apoptosis inhibition. Immunofluorescence revealed that DCAF13 localizes to the centrosome, cell-cell contacts and the nucleus of LuAD cells, indicating a potential role in transcription control. Functionally, DCAF13 is a predicted substrate recruiting unit of a CUL4-family ubiquitin ligase. Indeed, we show that DCAF13 binds to CUL4B and DDB1 to form an active ubiquitin ligase complex. In an effort to identify lung cancer specific relevant ubiquitylation substrates of DCAF13, we performed affinity-based interactome screens and non-affinity-based functional proteomics in LuAD cells. Cross-validation of these approaches revealed distinct tumor-suppressive transcription factors, which are known to play a role in tumorigenesis, embryogenesis and stem cell differentiation. Ongoing biochemical and transcriptomic analyses further determine the involvement of these transcription factors and DCAF13 in the establishment and maintenance of LuAD. Taken together, we nominate DCAF13 as a novel vulnerability in LuAD with potential implication in future targeted therapy strategies. Citation Format: Vinona T. Wagner, Yun-Chien Chang, Piero Giansanti, Rupert Öllinger, Thomas Engleitner, Bernhard Kuster, Florian Bassermann. A multi-omic screening approach identifies the E3-ubiquitin ligase DCAF13 as a novel vulnerability in lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2575.