Dissertation
The role of HuR in mediating ovarian cancer treatment
Doctor of Philosophy (Ph.D.), Drexel University
Mar 2016
DOI:
https://doi.org/10.17918/etd-7154
Abstract
An mRNA-binding protein, HuR (Human antigen R, aka ELAVL1), is highly elevated in many cancers, and is a master regulator of gene expression. HuR-regulated genes are involved in cancer cell survival, growth, and metastasis. In ovarian cancer, cytoplasmic accumulation of HuR is associated with poor prognosis. High HuR expression in ovarian cancer cells provides a rationale for targeting HuR as a therapeutic strategy. Here, we found that silencing HuR in ovarian cancer cells in culture by transient transfection of small interfering RNA (siHuR) or by stable expression of short hairpin RNA (shHuR) significantly decreased cell proliferation and anchorage-independent growth, and impaired migration and invasion. Furthermore, systemic administration of siHuR-conjugated folic acid (FA)-derivatized DNA dendrimer nanocarrier (3DNA®) to ovarian tumor-bearing mice suppressed tumor growth and ascites development, and significantly prolonged lifespan. Using NanoString gene expression analysis, we showed that suppression of HuR disrupts multiple essential cellular molecular pathways needed by ovarian tumor cells to survive, a finding that sets this therapeutic approach apart from other therapies that target a single gene. These results are the first to demonstrate the versatility of the 3DNA nanocarrier for in vivo targeted delivery of a cancer therapeutic, support the notion that HuR is a promising target, and support the potential use of FA-derivatized 3DNA dendrimer for siHuR targeted delivery to ovarian tumor cells for treatment of advanced ovarian cancer patients. Given that HuR serves as a predictive marker for gemcitabine efficacy in pancreatic cancer, we performed a retrospective study of ovarian cancer patients aiming to investigate the role that HuR plays in the response of high-grade serous ovarian tumors to chemotherapeutics. We found that there is no correlation between HuR intracellular localization and progression free survival (PFS) following second-line therapy with gemcitabine, usually administered in combination with carboplatin. We further performed ribonucleoprotein immunoprecipitation (RNP-IP) on ovarian cancer cells in culture to determine if HuR regulates deoxycytidine kinase, a metabolic enzyme that activates gemcitabine. We also examined the effects of carboplatin treatment on expression of HuR and the mitotic inhibitor WEE1, and on cell cycle kinetics. Treatment of cells with gemcitabine upregulated deoxycytidine kinase (dCK), while treatment with carboplatin upregulated both HuR and WEE1 expression. One would expect enhancement of gemcitabine activation and efficacy resulting from elevated dCK to be impeded by elevated WEE1 expression. This may explain why HuR cytoplasmic localization is not predictive of therapeutic response to combination gemcitabine/carboplatin therapy and PFS. These results suggest combination treatment of recurrent ovarian tumors with gemcitabine, carboplatin, and a WEE1 inhibitor may be potentially advantageous as compared to current clinical practices.
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Details
- Title
- The role of HuR in mediating ovarian cancer treatment
- Creators
- Yu-Hung Huang - DU
- Contributors
- Mauricio Reginato (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 7154; 991014632597204721