Abstract 451: AICAR targets oncogenic signaling pathways of MUC1-CT

Abstract

Abstract Lung cancer cells overexpress oncogenic mucin 1 (MUC1), whose C-terminal active subunit (MUC1-CT) is involved in lung tumor formation. Although a specific peptide against MUC1-CT has effectively blocked the MUC1 signaling pathway, intrinsic metabolites targeting MUC1 were not well studied. 5-aminoimidazole-4-carboxamide riboside (AICAR) is a purine biosynthesis intermediate and an analog of adenosine. Our study showed that high AICAR reduced lung tumor cell growth by increasing DNA damage and cell apoptosis. MUC1 was validated as one of the leading AICAR-binding proteins by virtual target screening and thermal stability assay. AICAR treatment dramatically degraded MUC1-CT at protein levels. Whole transcriptome analysis demonstrated that AICAR negatively regulated the Janus kinase (JAK) signaling pathway. Duolink proximity ligation assay revealed that JAK1 interacted with MUC1 directly, and AICAR treatment impaired this protein-protein interaction. Increased epidermal growth factor receptor (EGFR) activity was linked to upregulated expression of MUC1-CT in tissues from an EGFR transgenic mouse lung cancer model. AICAR treatment reduced phosphorylated EGFR, JAK1, and MUC1-CT in lung cancer cells. A mono-treatment with AICAR reduced tumor formation in a mouse lung xenograft model. Combination therapy with AICAR and small-molecule inhibitors against JAK1 or mutant EGFR reduced the growth of lung tissue-derived tumor organoids. Thus, our study has first disclosed a new ligand repressing the MUC1 activity in lung cancer that disrupts protein-protein interactions between MUC1-CT and other oncogenic proteins. Citation Format: Fareesa Aftab, Alice Rodriguez-Fuguet, Luis Silva, Ikei S. Kobayashi, Jiao Sun, Katerina Politi, Elena Levantini, Wei Zhang, Susumu S. Kobayashi, Wen Cai Zhang. AICAR targets oncogenic signaling pathways of MUC1-CT [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 451.