Acetylation of G3BP1 in Lung Cancer

High levels of Ras GTPase-activating protein-binding protein G3BP1, a critical regulator of RNA metabolism, have been reported to result in poor lung cancer prognosis. Overexpression of G3BP1 induced the epithelial-to-mesenchymal transition and enhanced the migration and invasion of breast cancer cells. Conversely, knockdown of G3BP1 in lung cancer cell lines with high G3BP1 levels resulted in attenuation of cancer cell growth. Moreover, treatment of lung cancer cells with HDAC inhibitors also showed promising therapeutic benefits. We recently found that G3BP1 is acetylated at a single lysine residue K376 and G3BP1 acetylation increased when cells were treated with HDAC inhibitors. Thus, we hypothesize that the benefits of HDAC inhibitors might in part manifest through the increase of G3BP1 acetylation. Our recent preliminary data showed that EGFR signaling, which is a critical regulator of cancer progression, modulated the acetylation of G3BP1 and its function in cellular response to stresses. The central hypothesis to be tested in this project is that G3BP1 acetylation can interfere with lung cancer progression and that targeting G3BP1 acetylation provides a novel therapeutic avenue for lung cancer. Aim 1 is to determine how G3BP1 acetylation interferes with lung cancer cell growth. Based on our recent success in generating G3BP1 KO cell lines using the CRISPR technology, we will generate knock-in cells with acetylation-mimicking or non-acetylatable G3BP1 mutants and test their effect on the proliferation of lung cancer cells. Aim 2 is to determine how EGFR signaling regulates the acetylation of G3BP1. We will utilize wild-type and mutant EGFR clones to examine the acetylation of G3BP1 in the presence and absence of EFG ligand. We will also employ the proteomic approach to identify G3BP1-interacting proteins. The latter approach will engage the proteomics component of the Redox Metabolism shared resource. The results from this aim will provide a more specific molecular target for modulating G3BP1 acetylation. Aim 3 is to examine the value of G3BP1 acetylation as a prognosis marker of lung cancer using an acetyl-G3BP1 antibody that we recently generated. We will engage both Biospecimen and Tissue Procurement and Biostatistics and Bioinformatics shared resources in this aim. If a positive correlation between G3BP1 acetylation and lung cancer prognosis is found, the clinical utility will be explored. The proposed studies will provide novel mechanistic insights into the role of G3BP1 acetylation in lung cancer, thus it is primarily aligned with the Cancer Cell Biology and Signaling program. The expected results will likely reveal novel targets for drug development, thus the project has immediate translational value and is well aligned with the Drug Discovery, Delivery and Translational Therapeutics program as well.