Date of Award


Degree Type


Degree Name

Master of Science


Anatomy and Cell Biology


Dr. Lynne-Marie Postovit


Recently, the stem cell factor Nodal has been correlated with metastatic competence in breast cancer. We investigated hypoxia as a regulator of Nodal as it is an important feature of stem and cancer cell microenvironments. We hypothesized that hypoxia up-regulates Nodal in poorly metastatic T47D breast cancer cells through the Hypoxia-Inducible Factor-1 (HIF-1) and Notch signalling pathways. We exposed cells to decreasing concentrations of O2 for varying amounts of time. 0.5% O2 for 48 h experienced a maximal induction of Nodal mRNA expression and protein levels, which persisted for up to 72 h with reoxygenation. HIF-lα over-expression and knock down experiments implicate a role for HIF-lα transcriptional regulation of Nodal. Dual luciferase assays, which investigated the Notch-responsive enhancer region (NDE) upstream of Nodal, showed activation in hypoxia. Mutations in the NDE abrogated this activity. This work reveals how a normally stem cell-associated factor can be up- regulated by hypoxia in cancer cells.



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