Breast cancer is one of the most prevalent forms of cancer in the United States, with one in every eight women developing the disease over the course of a lifetime. Besides being one of the most prevalent forms of cancer, it is also one of the most challenging to treat, with more than 40,000 women dying from the disease each year. Breast cancer therapies often utilize cytotoxic agents that cause damage to cancer cells, activating a form of programmed cell death called apoptosis. Activation of apoptosis results in the activation of cysteine proteases, known as caspases, which cleave protein substrates and lead to a disassembly of the cell. Inhibition of apoptosis is one of the central hallmarks of cance and the ability of cancer cells to evade cell death has been a major obstacle in breast cancer treatment. Caspase 2 (C2) has been shown to be a critical initiator of apoptosis in response to breast cancer chemotherapeutics. In a model experimental system, our lab has shown previously that activation of C2 can be regulated by metabolism through binding of a small signaling molecule, 14-3-3?. The release of 14-3-3? from C2 is regulated by 14-3-3? acetylation and this modification is controlled by the metabolic status of the cell. With extensive studies showing that cancer cells commonly have abnormal metabolic pathways, we propose that breast cancer cells modulate acetylation of 14-3-3? to survive genotoxic stressors. To elucidate how alterations in acetylation of 14-3-3? may contribute to the ability of breast cancer cells to evade cell death by cytotoxic agents, we propose to determine the enzymes regulating 14-3-3? acetylation, the mechanism of metabolic control, and the status of 14-3-3? acetylation in normal and breast tumor samples. Furthermore, we aim to explore how modulating acetylation will alter the chemoresponsiveness of breast cancer cells, both in culture and mouse models. The proposed research will utilize established breast cancer cell lines of varying chemosensitivities, whereby we will screen using specific acetylase and deacetylase inhibitors to identify the enzymes controlling 14-3-3? acetylation. The mechanism of metabolic control will then be evaluated by monitoring changes in enzyme binding and activity under different metabolic conditions. In addition, we will determine if the acetylation status of 14-3-3? is altered in breas cancer by analyzing both normal and primary human tumor samples/sections for acetylated 14-3-3? using immunohistochemistry. Finally, to determine whether modulating acetylation alters the chemoresponsiveness of breast cancer cells, relevant inhibitors will be combined with chemotherapeutic agents and assayed for their ability to induce cell death in both breast cancer cell lines and xenografted tumors. We expect that enhancing 14-3-3? acetylation will increase the susceptibility of breast cancer cells to chemotherapy-induced apoptosis, potentially leading to the discovery of a new therapy that can be used in combination with standard chemotherapies for more effective breast cancer treatments.
|Johnson, Erika Segear; Lindblom, Kelly R; Robeson, Alexander et al. (2013) Metabolomic profiling reveals a role for caspase-2 in lipoapoptosis. J Biol Chem 288:14463-75|