The work presented herein examines the potential impact of extracellular matrix (ECM) protein-integrin receptor interactions on tumour cell chemotherapeutic sensitivity, proliferation and anchorage-independent growth. First, a screen was performed to assess the impact of ECM proteins on the survival of various tumour cell lines treated with different chemotherapeutic agents, however no significant modulation by ECM was detected. To more specifically understand potential influences of ECM on tumour cell phenotypes, a siRNA approach targeting integrin beta1, an important ECM receptor component, was employed. Integrin beta1 depletion studies conducted in paired cisplatin sensitive and resistant ovarian cancer cells did not support a role for ECM-integrin receptor binding in drug sensitivity. Similarly, reduction of integrin beta1 protein using the siRNA approach did not impact the adhesion or adherent growth of the cancer cell lines studied. However, integrin beta1 was shown to be necessary for the anchorage-independent growth of all tumour cell lines tested in soft agarose colony formation assays. The importance of integrin beta1 for anchorage-independent growth of PC3 cells was further confirmed using both neutralizing antibodies to the receptor subunit and a signaling-impaired splice variant of integrin beta1. Depletion of the integrin ligand, fibronectin, from the tumour cell culture medium similarly reduced soft agarose colony formation, suggesting that ligation of beta1 integrins is necessary for anchorage-independence. Co-immunoprecipitation studies revealed the formation of a de novo interaction between beta catenin and integrin beta1 when tumour cells were transitioned to grow anchorage-independently. These findings suggest a model whereby ligation of the beta1 integrin-containing receptors by soluble fibronectin drives the anchorage-independent growth of tumor cells through a beta catenin signaling pathway.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/28021 |
| Date | January 2008 |
| Creators | Schooley, Allana M |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 172 p. |
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