Ovarian cancer (OC) is the second most common gynecologic cancer; however it is responsible for the most gynecologic cancer-related deaths. Apoptosis evasion is an important mechanism in OC tumorigenesis, and the prototypic anti-apoptotic protein, B-cell lymphoma 2 (Bcl-2), is often overexpressed in OC tumors. Gaining a better understanding of the mechanism(s) behind Bcl-2 overexpression and potential extra-anti-apoptotic functions of Bcl-2 could elucidate the importance of elevated Bcl-2 in OC. In the current study, I show through immunohistochemical analysis of normal, benign, and OC tissue sections, that both epithelial and stromal Bcl-2 expression decreases with OC progression. However, the number of Bcl-2-positive lymphocyte nests and the size of these lymphocyte nests increase dramatically with OC progression. Additionally, this study shows that lysophosphatidic acid (LPA), a glycerophospholipid frequently elevated in serum and ascites fluid of OC patients, upregulates Bcl-2 in OC cells. Bcl-2 enzyme-linked immunosorbant assay (ELISA), western blot analysis, reverse transcriptase polymerase chain reaction (RT-PCR), and luciferase reporter assays reveal that LPA increases Bcl-2 promoter, messenger RNA (mRNA), and protein levels in OC cells, but not in normal immortalized ovarian surface epithelial (IOSE) cells. LPA also increases secreted levels of Bcl-2. In vitro human umbilical vein endothelial cell (HUVEC) tube formation assays show that OC-derived Bcl-2 or recombinant human (rh) Bcl-2 promotes aberrant formation of tube-like structures. Though extracellular Bcl-2 does not affect HUVEC cell viability, it may cause aberrant tube formation by inhibiting HUVEC migration. Finally, Bcl-2 ELISA reveals that urinary Bcl-2 levels in OC patients are higher than those in normal individuals and patients with benign gynecologic disease. Urinary Bcl-2 also complements serum CA125 when the two are compared in parallel samples. Furthermore, urinary Bcl-2 decreases following cytoreductive surgery. Altogether, the results suggest that Bcl-2 is important in OC tumorigenesis and angiogenesis. Additionally, urinary Bcl-2 may be a valuable non-invasive biomarker for OC diagnosis and/or screening. Consequently, further elucidation of mechanisms of Bcl-2 overexpression and its extra-apoptotic functions could lead to improved treatment and diagnostic strategies for OC patients.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-7357 |
| Date | 13 December 2010 |
| Creators | Anderson, Nicole Shree |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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