All ETDs from UAB

Advisory Committee Chair

David T Curiel

Advisory Committee Members

Alexander Pereboev

Jackie Parker

Selvarangan Ponnazhagan

Theresa Strong

Document Type

Dissertation

Date of Award

2010

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Cancer still remains a major public health concern despite improvements in primary prevention, early detection and advanced treatments. Cancer gene therapy using human adenovirus serotype 5 (HAdV-5) as a vector has been explored as a new therapeutic approach. HAdV-5 infection is initiated by binding to the coxsackie virus and adenovirus receptor (CAR), its primary cellular receptor. However, the levels and patterns of expression of CAR vary greatly in clinical tumor tissue samples, and the expression lev-els tend to decrease as the tumors progress. The low level expression of CAR in target cancer cells diminishes the utility of HAdV-5 as a vector for cancer gene therapy. To overcome this expression problem, we have developed and investigated novel modifica-tions of HAdV-5 vectors for: 1) efficient gene delivery via a CAR-independent mecha-nism, and 2) tropism expansion from CAR-positive to CAR-negative tumor cells. For the first strategy, a range of chimeric HAdV vectors displaying the fiber shaft and knob do-mains of species B HAdVs (HAdV-3, -11, or -35) has been developed, since species B HAdVs utilize CD46 as a receptor for infection. CD46 is highly expressed in the majority of cancer cells. The fiber chimeric HAdV vectors were compared with the original HAdV-5 vector for transductional efficiency in a variety of cancer cell lines, using luciferase as a reporter gene. The chimeric HAdV vectors had distinct infectivity in dif-ferent types of cancer cells as well as a CAR-independent mechanism for infection. In particular, of the developed chimeric HAdV vectors, a vector incorporating the HAdV-3 fiber shaft and knob domains achieved the highest ratio of gene transfer ratio in advanced prostate cancer as compared to normal prostate cells, suggesting that this vector could potentially be used for prostate cancer gene therapy. For the second strategy, we have genetically developed a fiber-mosaic HAdV vector incorporating both a chimeric fiber protein displaying the HAdV-3 shaft and knob domains, as well as the native HAdV-5 fiber protein. Both types of the fiber proteins functionally utilized their two distinct receptors, CAR and CD46. Importantly, in a mixed population of two different types of cells, which simulates a tumor-like environment, the fiber-mosaic HAdV vector transferred a trans-gene into both cell types utilizing CAR and CD46, demonstrating tropism expansion. These results indicate that fiber modification of the HAdV vector is a suitable platform for future HAdV vectors capable of a variety of clinical applications for cancer gene therapy.

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