Abstract 2795: EGF-upregulated ESSENCE promotes colorectal cancer growth through stabilizing CAD and ferroptosis defense

Background: EGFR/MAPK signaling pathway is usually activated in various types of cancer. The roles and downstream targets of long non-coding RNAs (lncRNAs) induced by this pathway in colorectal cancer (CRC) have not been fully elucidated. Methods: LncRNAs triggered by EGFR/MAPK signaling were screened and validated after EGF or Selumetinib treatment in CRC cells. The 5' and 3' rapid amplification of cDNA ends (RACE) assay was performed to identify the full length of the interested lncRNA. The biological function of lncRNA was examined through RNA interference or overexpression, coupled with in vitro and in vivo experiments. Biotinylated RNA pull-down and mass spectrometry analysis were used to determine the direct downstream targets. Mechanistically, chromatin immunoprecipitation (ChIP) and luciferase reporter assays were conducted to explore the transcription factor and the potential binding sites in the promoter region of the lncRNA. Co-immunoprecipitation, ubiquitination assay, protein turnover assay, and immunohistochemistry staining were performed to determine the regulatory mechanism, E3 ligase and recognition degron. C11 BODIPY staining and flow cytometry analysis were conducted to detect the lipid peroxidation levels in the cells. The CRC-patient derived xenograft (PDX) model was used to explore potential applications for CRC clinical therapy. Results: ESSENCE (EGF Signal Sensing CAD's Effect, ENST00000415336) was identified as being upregulated by the EGFR/MAPK signaling pathway, with transcription factor EGR1 mediating this induction. ESSENCE was upregulated in most CRC and predicted poor prognosis. It acted as a potent oncogenic molecule that regulated CRC cell proliferation, foci formation and tumorigenesis through regulating carbamoyl-phosphate synthetase 2, aspartate transcarbamylase and dihydroorotase (CAD) protein stability, ubiquitination level, and expression. Intriguingly, we found that ESSENCE directly interacts with CAD and competitively attenuates CAD degradation mediated by its newly identified E3 ligase KEAP1, thereby suppressing ferroptosis and promoting CRC progression. Importantly, the combinational treatment of the MEK inhibitor Selumetinib and the ferroptosis inducer Sulfasalazine synergistically suppresses ESSENCE-high expression CRC growth in a CRC derived PDX mouse model. Conclusion: Our findings demonstrate the crucial role of ESSENCE in mediating CRC progression by regulating CAD stabilization and ferroptosis defense. Synergistically targeting MEK and inducting ferroptosis represents a promising therapeutic strategy for ESSENCE-high expression CRC. Citation Format: Xiangqi Meng, Xiaoshan Xie, Ning Ma, Hongyan Yu, Mong-Hong Lee. EGF-upregulated ESSENCE promotes colorectal cancer growth through stabilizing CAD and ferroptosis defense [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2795.