Abstract C083: Targeting anoikis resistance: The role of Tropomyosin2.1 in breast cancer cell survival

Abstract Cells constantly interact with their microenvironment to maintain normal growth and function. The extracellular matrix (ECM), a key component of this microenvironment, plays a crucial role in regulating cell fate. In non-transformed adherent cells, detachment from the ECM activates anoikis, a specialized form of programmed cell death that prevents inappropriate survival and growth in suspension. However, cancer cells can evade anoikis, enabling anchorage-independent growth, a hallmark of metastatic potential. Previous studies have shown that many cancer cells exhibit low expression of Tropomyosin 2.1 (Tpm2.1), an actin-binding cytoskeletal protein essential for sensing matrix rigidity. The presence or absence of Tpm2.1 switches cancer cells between anchorage-dependent (non-transformed) and anchorage-independent (transformed) growth states. However, the downstream mechanisms by which Tpm2.1 loss promotes anchorage-independent survival remain poorly understood. Here we show that restoring Tpm2.1 expression in breast cancer cells induces anoikis, inhibits proliferation in suspension, and impairs cell migration. To identify downstream pathways affected by Tpm2.1, we performed RNA sequencing and metabolomic profiling of apoptotic and non-apoptotic cancer cells in suspension. RNA-seq analysis revealed compensatory survival mechanisms, including activation of PI3K-Akt signaling and upregulation of intercellular adhesion molecules such as ICAM1. Pharmacological inhibition of Akt, EphA2, or ICAM1 significantly enhanced apoptosis under suspension conditions, indicating that anoikis resistance can be therapeutically targeted. Metabolomic analysis further showed that Tpm2.1-expressing cells exhibit a lower NAD+/NADH ratio and reduced levels of pyruvate and acetyl-CoA in suspension, suggesting that Tpm2.1 alters metabolic pathways to suppress survival under suspension conditions. Together, these findings provide important mechanistic insights into how Tpm2.1 expression downregulates signaling and metabolic pathways required for anchorage-independent survival, offering potential targets to overcome anoikis resistance in metastatic cancer cells. Citation Format: Nehal Dwivedi, Anat Galis Vivante, Michael P. Sheetz, Guy Nir. Targeting anoikis resistance: The role of Tropomyosin2.1 in breast cancer cell survival [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr C083.