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Microphysiometry Studies of Rapid Binding of Insulin-Like Growth Factor I by Parental and Transfected Mammary Epithelial Cell Lines

Breast cancer is a leading cause of cancer death of women in the U.S. today. Members of the family of insulin-like growth factors (IGFs) are proposed to play a major role in the development and subsequent uncontrolled proliferation of breast cancer cells. Insulin-like growth factor-I (IGF-I) is known to be a potent mitogen for mammary epithelial cells. IGF-I acts by binding to cell surface receptors, thereby stimulating a cascade of events leading to cell division. In the interest of interrupting the effect of IGF-I on cancerous mammary epithelial cells, an understanding of how IGF-I behaves in the presence of other extracellular components is needed. This study examines the IGF-I response of SV40-IGF-I, an immortalized bovine mammary epithelial cell line which secretes IGF-I constitutively.

The microphysiometer allows real-time sampling of cellular activity by measuring the excretion of protons from a sample of cells stimulated by IGF-I binding. The contributions of other factors in enhancing or suppressing stimulation can be compared by examining the pH response of cells exposed to IGF-I in the presence of these factors. We present data showing the stimulatory effect of IGF-I in a dose dependent manner on the SV40-IGF-I cell line.

In addition, we compare IGF-I stimulation with stimulation by long R3IGF-I, a substituted analogue of IGF-I having a reduced binding affinity for the IGF binding proteins. We examine the effect of insulin-like binding protein-3 (IGFBP-3) both in the presence and absence of IGF-I, finding no IGF-I independent effect in the rapid binding experiment and no effect on stimulation of IGFBP-3 pre-incubated cells by subsequent IGF-I challenge. This is of particular interest due to recent work demonstrating an IGF-independent IGFBP-3 response in a number of cell lines. Binding studies to correlate with the rapid binding stimulation show binding of the IGFBP-3 molecule with high affinity to a small number of surface receptors on the SV40-IGF-I cell.

Analysis of the extracellular environment and the components contributing to the binding of IGF-I to the cell membrane receptor will provide information for the development of interventions to slow or interrupt the process of IGF-I binding and therefore cancer growth. Optimization of the Cytosensor(r) Microphysiometer System for the (transfected) SV40-IGF-I and the (parental) MAC-T cell lines was achieved to continue comparison studies of autocrine and paracrine stimulation of bovine mammary epithelial cells by IGF-I.

This work was supported by the Whitaker Foundation Biomedical Engineering Grant. / Master of Science

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/35363
Date13 November 1998
CreatorsRobinson, Rose Marie
ContributorsChemical Engineering, Forsten-Williams, Kimberly, Davis, Richey M., Akers, Robert Michael
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
Detected LanguageEnglish
TypeThesis
Formatapplication/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/
RelationChapter1.pdf, Chapter3.pdf, Vita.pdf, Chapter4.pdf, Appendix_A.pdf, Bibliography.pdf, Chapter6.pdf, Chapter5.pdf, CONTENT_DOC.pdf, ACKn_DOC.pdf, Abstract.pdf, thesistitle.pdf, Chapter2.pdf

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