| Breast cancer is the most frequently diagnosed cancer amongst women in the United States, and is the second leading cause of cancer related death. This year alone, it is anticipated that approximately 40,000 women will die due to this disease. With breast cancer, improvements in the areas of diagnosis and treatment are desperately needed, and would play a huge role in reducing disease-associated mortality.;This study thoroughly examines a novel technology to detect and treat metastatic breast cancers. In engineering a recombinant adenoviral (Ad) vector to express transgenes in a cancer-selective manner, our primary goal was to create a modality to be used in both diagnostic and therapeutic applications of advanced stage breast cancer. This was accomplished through use of the two-step transcriptional amplification system (TSTA) in conjunction with adenoviral vector based technology. In the past, the TSTA system showed the ability to greatly augment the activity of a weak, tissue-specific promoter without affecting tissue selectivity. Here, the tumor specific Mucin1 (MUC1) promoter was incorporated into the TSTA system and successfully achieved amplified transgene expression exclusively in breast cancer cells. Through use of xenograft models of breast cancer, the in vivo targeting ability of the AdMUC1 TSTA system was demonstrated.;To increase the functionality of the TSTA system, a series of multigene expressing TSTA systems were developed. These systems allowed for the amplified expression of multiple transgenes in a tissue specific manner. In order to evaluate the therapeutic potential of these systems, both the HSV-sr39tk suicide gene and a firefly luciferase reporter gene were integrated into a bidirectional TSTA configuration. This system achieved functional cell killing in vitro when combined with the pro-drug gancyclovir, and is currently being evaluated in vivo. An additional multigene TSTA system capable of expressing up to four reporter or therapeutic genes was also developed and tested in vitro.;Through this work, we have demonstrated the strong potential of the AdMUC1 TSTA systems in both diagnostic and therapeutic applications of breast cancer, and believe that they can potentially play a significant role in reducing mortality from this disease. |
