Date of Graduation

5-2012

Document Type

Thesis (MS)

Program Affiliation

Biomedical Sciences

Degree Name

Masters of Science (MS)

Advisor/Committee Chair

Steven A. Curley, MD

Committee Member

Gary E. Gallick, PhD

Committee Member

Anil Sood, MD

Committee Member

Sunil Krishnan, MD

Committee Member

Lon J. Wilson, PhD

Abstract

Gemcitabine is a potent nucleoside analogue against solid tumors however drug resistance rapidly emerges. Removal of gemcitabine incorporated in the DNA by repair mechanisms could potentially contribute to resistance in chemo-refractory solid tumors. In this study, we evaluated homologous recombination repair of gemcitabine-stalled replication forks as a potential mechanism contributing to resistance. We also studied the effect of hyperthermia on homologous recombination pathway to explain the previously reported synergy between gemcitabine and hyperthermia. We found that hyperthermia degrades and inhibits localization of Mre11 to gemcitabine-stalled replication forks. Furthermore, gemcitabine-treated cells that were also treated with hyperthermia demonstrate a prolonged passage through late S/ G2 phase of cell cycle in comparison to cells treated with gemcitabine alone. This coincides with inhibition of resolution of γH2AX foci. Our findings also demonstrate that thermal sensitization of human hepatocellular carcinoma cell lines to gemcitabine is mediated through an Mre11-dependent homologous recombination repair pathway. Combination of non-invasive radiofrequency field-induced hyperthermia and gemcitabine was superior to either therapy alone (p

Keywords

gemcitabine, stalled replication fork, homologous recombination, hyperthermia, radiofrequency, hepatocellular carcinoma