Abstract 211: Applying cellular thermal shift assays to uncover novel regulators of epithelial to mesenchymal transition in triple negative breast cancer

Abstract Metastatic Breast Cancer is accountable for over half a million deaths worldwide each year, the majority of which are from the triple negative breast cancer (TNBC) subtype, known to be highly aggressive, metastatic and resistant to targeted therapy. Metastasis is driven by the ability of cancer cells to undergo epithelial to mesenchymal transition (EMT), a cell state transition involving a gain of stemness, cell motility and chemoresistance. EMT has been well characterized using a range of techniques based upon quantitative proteomics and transcription profiling, yet targeting EMT to prevent tumor metastasis and chemoresistance is an obstacle that remains to be fully overcome. Using a cellular thermal shift assay coupled with mass spectrometry (CETSA-MS), we have measured changes in protein stability upon induction of EMT and have uncovered key enzymes in the citric acid (TCA) cycle that are stabilized during EMT of human mammary epithelial cells. Such enzymes are responsible for the conversion of TCA cycle intermediates required for a recently discovered post-translational modification. In TNBC cells, we find that loss of these enzymes causes not only global changes to crucial post-translational modification of mitochondrial proteins, but very specific alterations in several cytoskeletal proteins, leading to altered EMT status as well as reduced tumor growth and initiation both in vitro and in vivo. This demonstrates the importance of TCA cycle-controlled post-translational modification of cytoskeletal proteins in tumorigenesis and establishes basis for further investigation into their role in EMT and metastasis of breast cancer. Through pharmacological inhibition and immunofluorescence imaging, we discovered regulators of post-translational modifications that may be viable drug targets to overcome chemoresistance and relapse in TNBC patients with limited and inefficacious options. Citation Format: Jessica A. Lidster, Ser Yue Loo, Zhengwei Wu, Lingyun Dai, Seow Qi Ng, Nayana Prabhu, Dennis Kappei, Wai Leong Tam. Applying cellular thermal shift assays to uncover novel regulators of epithelial to mesenchymal transition in triple negative breast cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 211.