Author ORCID Identifier
0000-0002-0160-1620
Date of Graduation
5-2023
Document Type
Dissertation (PhD)
Program Affiliation
Genetics and Epigenetics
Degree Name
Doctor of Philosophy (PhD)
Advisor/Committee Chair
Don L. Gibbons, M.D., Ph.D.
Committee Member
Michelle Barton, Ph.D.
Committee Member
Jonathan Kurie, M.D.
Committee Member
Sendurai Mani, Ph.D.
Committee Member
Lauren Byers, M.D.
Abstract
Lung cancer metastasis is leading the causes of cancer-related mortality in the United States and worldwide. Epithelial-to-mesenchymal transition (EMT) is a model for metastasis that results in loss of specialized epithelial cell contacts and acquisition of mesenchymal invasive capacity. Zinc finger E-box-binding homeobox 1 (ZEB1) recognizes and binds to E-boxes of epithelial gene promoters to repress its transcription. ZEB1 has inconsistent molecular weights, which have been attributed to post-translational modifications (PTMs). In the presented dissertation, I specifically addressed the gap in the molecular mechanisms by which PTMs of ZEB1 regulate its ability to induce EMT and how its activity might be therapeutically targeted. In a previous work from our lab, tandem-mass spectrometry analysis on ZEB1 was conducted to uncover any PTMs that might impact its stability, protein interactions, and function, which resulted in the identification of a novel K811 acetylation site. To define the role of ZEB1 acetylation in regulating function, we generated ZEB1 acetyl-mimetic (K811Q) and acetyl-deficient (K811R) mutant-expressing non-small cell lung cancer cell lines (NSCLC). I demonstrated that the K811R ZEB1 (125 kDa) has a shorter protein half-life than wild-type (WT) ZEB1 and K811Q ZEB1 (~225 kDa), suggesting that lack of ZEB1 acetylation in the lower molecular weight form affects protein stability. Further, the acetylated form of ZEB1 recruits the nucleosome remodeling and deacetylase (NuRD) complex to bind the promoter of mir200c-141 and SEMA3F genes. RNA-sequencing revealed that WT ZEB1 and K811Q ZEB1 downregulate the expression of epithelial genes to enhance NSCLC motility, invasion, and metastasis, while the K811R ZEB1 does not. Our findings establish that the K811 acetylation promotes ZEB1 protein stability, interaction with other protein complexes, and subsequent invasion/metastasis of lung adenocarcinoma via epithelial-to-mesenchymal transition.
Keywords
ZEB1, post-translational modifications, epithelial-to-mesenchymal transition (EMT), metastasis, epigenetic, transcription factor