Molecular Mechanisms of Circulating Tumor Cell Adhesion in Breast Cancer Metastasis

During hematogenous metastasis, tumor cells dissociate from a primary tumor, migrate through the tissue space, and enter the circulatory system. The circulating tumor cells (CTCs), once bloodborne, travel to distant sites, where they adhere to the endothelial cells lining the vessel wall, potentially extravasate, and form secondary tumors if directed by niche factors. Determining the mechanisms of each of these steps can provide insights into novel diagnostics and therapeutics for cancer. Of particular interest is elucidating the molecular mechanisms by which metastatic cells adhere to the endothelium while resisting the disruptive shear exerted by the blood flow. We hypothesized that breast cancer cell adhesion is mediated by interaction of endothelial E-selectin with its counter-receptor(s) expressed on breast cancer cells. This hypothesis was tested by using a variety of specialized biochemical techniques and tumor cell/endothelial cell adhesion assays. It was found that breast cancer cells express gangliosides (sialylated lipids), a novel glycoprotein ligand known as Mac-2BP, and CD44 molecules that are functional E-selectin ligands under physiological flow conditions. Further efforts were made to find whether E-selectin ligand activity is related with breast cancer stem-like cells (BCSCs), which are the subset of tumor cells thought to possess properties necessary to maintain and grow tumor mass. For this purpose, breast cancer cell lines which were BCSCs and non-BCSCs were analyzed for E-selectin ligand activity. Interestingly, the non-BCSC cells expressed higher levels of E-selectin ligand activities than that of BCSCs. Epithelial to mesenchymal transition (EMT) is a process by which tumor cells are believed to gain metastatic potential and BCSC properties. The results indicated that E-selectin ligand activity of breast cancer cells may be regulated by EMT. These data suggesting close association of E-selectin ligands with breast cancer metastasis motivated us to develop methods to find E-selectin ligand activity of tumor tissues. First, the E-selectin ligand activity of cancer tissues was analyzed by immunohistochemistry (IHC). This study showed that E-selectin reactive molecules are abundantly expressed by some cancer tissues. However, mere presence of molecules reactive to E-selectin under static (no-flow) conditions is not sufficient for E-selectin ligand function. The E-selectin ligands need to possess certain biophysical properties to serve as adhesion molecules resisting the shear forces exerted by the flow of circulatory fluid (e. g., blood). To analyze the E-selectin ligand activity of tissue samples under physiological flow conditions, an assay termed dynamic biochemical tissue analysis (DBTA) was developed. Ultimately, the E-selectin ligands found in this study potentially reveal a new therapeutic target for breast cancer, and DBTA provides a tool for the development of novel diagnostics and prognostics for cancer based on E-selectin ligands.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemical Engineering (Engineering and Technology)

Grantor dc:publisher

Ohio University

Year dc:date

2013

Author dc:creator

• Shirure, Venktesh S.

Contributors dc:contributor

• Burdick, Monica M.

• Biochemistry
• Biology
• Biomedical Engineering
• Biomedical Research
• Biophysics
• Chemical Engineering
• selectin
• E-selectin
• shear
• cell adhesion
• sLeX
• sLeA
• dynamic tissue analysis
• dynamic cell adhesion
• cell tethering
• cell rolling
• breast cancer stem cells

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1357706517

OAI identifier oai:identifier

oai:etd.ohiolink.edu:ohiou1357706517