Investigating the biological and clinical implications of Endo180 in breast cancer

Wang, Kai

Abstract

Endo180 is a 180 kDa type-1 transmembrane receptor that belongs to the mannose receptor family and interacts with extracellular / intracellular collagens. Endo180 expression is correlated with tumour grade, disease progression and poor prognosis in several cancer types including breast cancer and prostate cancer, and Endo180-dependent collagen remodelling is proved to have mechanistic roles in the promotion of breast cancer progression and metastatic bone lesion pathology. It has recently been reported that Endo180 ectodomain is released from breast cancer cells and that measurement of Endo180 in plasma – alone or in combination with CA 15-3 antigen – provides an accurate method for classifying metastatic bone disease. It is also indicated that Endo180 levels in plasma are modulated following treatment with bisphosphonates. Therefore, the aim of this project is to further explore the clinical and biological implications of Endo180 in breast cancer. Prior to that, an enzyme-linked immunosorbent assay (ELISA) for Endo180 quantification was first developed and optimised, to facilitate further consideration of Endo180 in the broader clinical setting. The newly developed assay provided an accurate and efficient method for Endo180 measurement in different types of samples. Following the development of ELISA, Endo180 levels in prospectively collected patient samples were measured, and retrospective-blinded-evaluation was conducted in collaboration with the University of Liverpool. The result indicated that the level of plasma Endo180 in advanced breast cancer patients were significantly higher than early breast cancer patients. To investigate Endo180 modulation under bisphosphonate treatment, in vitro treatment of breast/prostate cancer cells and osteoblasts with bisphosphonates were carried out. The result showed that the expression of Endo180 in breast cancer cell MDA-MB-231 was inhibited by bisphosphonates, which led to a decrease of Endo180 levels on the cell surface and released into the media. On the contrary, Endo180 expression and release levels in osteoblasts were not significantly influenced by bisphosphonates, with an increase on cell surface Endo180 level under the treatment. To further explore the mechanism under the release of Endo180, several factors that might be functional in the release of Endo180 from tumour cells and osteoblasts were investigated. It was found that MMPs could participate in the release of Endo180 from breast cancer cells, and MMP-2 was shown to influence the level of Endo180 that forms complex with other molecules. We also found that enabling Endo180 expression in MCF-7 cells could trigger the activities of MMP-2 / -9. The indirect co-culture of breast cancer cells and osteoblasts did not influence the release of Endo180 from breast cancer cells, while osteoblasts showed a decrease in Endo180 release. Indirect co-culture with osteoblasts could trigger the intake of Endo180 by prostate cancer cells, while osteoblasts were not influenced. From this study, we have shown the feasibility of plasma Endo180 as a potential biomarker for advanced breast cancer, the regulation of Endo180 release and expression by bisphosphonates, and the potential mechanisms for Endo180 release.

Citation

Wang, K. Investigating the biological and clinical implications of Endo180 in breast cancer. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4222284

• Thesis Type: Thesis
• Deposit Date: Mar 9, 2020
• Publicly Available Date: Feb 23, 2023
• Keywords: Biomedical sciences
• Public URL: https://hull-repository.worktribe.com/output/4222284
• Additional Information: School of Life Sciences, The University of Hull
• Award Date: Jun 1, 2017