Date of Award
2019
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biotechnology Science and Engineering
Subject(s)
Pancreas--Cancer--Molecular aspects., Fatty acid-binding proteins.
Abstract
Pancreatic ductal adenocarcinoma (PDAC) represents 85% of pancreatic cancers. With early stage diagnosis, PDAC has a relative five-year survival rate of 34% but drops to 3% with metastasis. There is a lack of distinct symptoms and dependable biomarkers which delays diagnosis, leading to poor prognosis. Angiopoietin-like 4 (ANGPTL4) protein has been indicated in the progression of several types of aggressive cancer. ANGPTL4 is natively present in two fragments, an amino-terminus coiled-coil domain (nANGPTL4) and a carboxy-terminus fibrinogen-like domain (cANGPTL4), which have demonstrated diverse biological functions. Biochemical studies have been performed but a full structural understanding of functions and interactions is not available. Overexpression of ANGPTL4 has been found in pancreatic tumor tissues of all stages. Its complexity and ability to target various cancer cell microenvironments, endothelial cells, and metabolic activities makes it a prime candidate for therapeutic intervention. The goal of this research was to acquire knowledge of cANGPTL4’s molecular role in PDAC progression by comprehending its mechanisms of action through structure-function studies that would enable the development of therapeutics. In order to accomplish this goal, differential expression of hypoxia induced ANGPTL4 was compared between hypoxia-induced expression of ANGPTL4 between common pancreatic and breast cancer cell lines. Furthermore, crystal structures of cANGPTL4 were investigated in complex with various ligands such as carbohydrates, fatty acids, and glycerol. Hypoxia-induced expression of ANGPTL4 was shown to be largest in Pancreases-1 (pancreatic cancer) and MDA-MB231 (breast cancer) cells. Both of these forms of cancer have highly invasive phenotypes. Capan-1, pancreatic cancer cells that are not well differentiated, showed the third largest increase in ANGPTL4 expression. cANGPTL4 was shown to be co-localized with Integrin-beta1 in Panc-1 cells with immunofluorescence and confocal imaging. Previous research revealed cANGPTL4 interacts with Integrin-beta1, resulting in reduced cell-cell contact mediating metastasis. Finally, three crystallographically derived structures were determined of cANGPTL4 with a different ligand. A crystal structure of cANGPTL4 with glycerol was solved to a crystallographic resolution of 2.11 angstrom, cANGPTL4 with palmitic acid to 1.75 angstrom, and cANGPTL4 with myristic acid to 2.37 angstrom. The binding of palmitic acid was revealed in crystal structures, cell culture assays with immunofluorescence, and a thermal shift assay using a Tycho NT.6 from Nanotemper. This combined data indicate cANGPTL4 aids in pancreatic cancer cell progression by providing cells with both energy and biological molecules required for proliferation.
Recommended Citation
Tarver, Crissy L., "Molecular role of angiopoietin-like 4's carboxy-terminal domain in pancreatic ductal adenocarcinoma progression" (2019). Dissertations. 171.
https://louis.uah.edu/uah-dissertations/171