Relatively little is known about metastasis, the spread of cancer from the site of its origin to different organs in the body. Aberrant glycosylation of cell surface glycoproteins in cancer cells has been implicated in promoting cancer metastasis and consequent poor survival of cancer patients. In particular, aberrant glycans terminating in α-N-acetylgalctosamine (GalNAc), specifically recognized by the lectin Helix pomatia agglutinin (derived from the albumin gland of the Roman snail, Helix pomatia), have been described as a hallmark of aggressive cancers of the breast and several other sites. The research described in this thesis aims to study the role of HPA binding glycans in one of the most important, but poorly understood steps of the metastatic cascade namely cancer cell-endothelial cell adhesion and transendothelial migration, using a rocking adhesion assay system in a model of breast cancer metastasis. Three breast cancer epithelial cell lines - MCF 7 and ZR 75 1, derived from breast cancer metastases cells, and BT 747, derived from primary breast cancer were studied during adhesion to, and migration across, monolayers of human umbilical vein endothelial cells (HUVECs) . Initially, a confocal microscope compatible rocking adhesion assay system was developed and optimized in house. The rocking adhesion assay system was then used to study the role of HPA binding glycans in the adhesion of cancer cells to the endothelial cells. Results from the rocking adhesion assays showed a significant inhibition in the adhesion of MCF 7 and ZR 75 1 cells thereby providing evidence that HPA binding glycans may play a functional role in the adhesion of breast cancer cell to endothelial cells. Behavior of the cancer cells post adhesion was studied using 24 hour time series experiments with a smartslide system and confocal microscopy. Further high resolution imaging was also carried out using scanning electron microscopy. The results have provided evidence that the behavior of cancer cells during adhesion and transendothelial migration during metastasis is similar to that described for leucocytes during the inflammatory response. Like leucocytes, after adhesion, cancer cells were imaged moving along the endothelial cell layer. The imaging further showed the retraction of endothelial cells and the cancer cells settling and dividing in the gap produced by endothelial retraction. In addition to this, transcellular migration was also imaged using scanning electron microscopy.
Bapu, Deepashree
Supervisors: Brooks, Susan ; Kadhim, Munira ; Runions, John
Faculty of Health and Life SciencesDepartment of Biological and Medical Sciences
Year: 2012
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