Abstract 1444: c-FLIP antagonizes the survival of extracellular matrix detached cancer cells

Abstract The metastasis of cancer cells to distant sites accounts for over 90% of cancer related deaths. In order to metastasize, cancer cells must be able to survive during extracellular matrix (ECM) detachment, namely by blocking anoikis – caspase dependent cell death – and restoring metabolic deficiencies. Such barriers during tumorigenesis are abrogated through activation of oncogenes, and/or inhibition of tumor suppressors. Elucidating the signaling pathways involved in cancer cell metastasis is a crucial step in designing effective therapeutic interventions. Surprisingly, our investigation has revealed that cellular FLICE-like Inhibitory Protein (c-FLIP), a protein known for its anti-apoptotic function, antagonizes the survival of ECM-detached cancer cells. Additionally, we demonstrated that oncogenic signaling results in the downregulation of c-FLIP expression further suggesting that cancer cells can benefit from diminished FLIP levels. We observed that this repression of c-FLIP expression is a consequence of MEK-ERK signaling. Our study also suggests that the mechanism underlying this paradoxical c-FLIP pathway involves the induction of β-catenin degradation through inhibition of GSK-3β phosphorylation by p38 MAPK. This results in the ubiquitination and subsequent degradation of β-catenin which could contribute to reduced proliferation and migration. Citation Format: Matyas Abel Tsegaye, Kyle McGeehan, Mati Nemera, Zachary T. Schafer. c-FLIP antagonizes the survival of extracellular matrix detached cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1444.