553. A Potent Replicative Delta Adenoviral Vector for HPV Tumors

ADENOVIRUS VECTORS: APPLICATIONS in NG and HG conditions, but the latter to a lesser extent. Control vector AdGFP had no effect on viability. Conclusion: Decreased viability observed in HAECs under HG conditions can be reversed by overexpression of MnSOD and CuZnSOD. As such, antioxidant overexpression may hold promise in protecting endothelial cells against hyperglycemic conditions.

551. Enhanced Cell Killing Effect of E1 Modified Adenoviruses Expressing HSV-TK Suicide Gene Yoon-A Kang, Dong Hyun Ko, Jaesung Kim Kim, Young-Sook Lee, Oh-Joon Kwon, Joo Hyuk Sohn, Chae-Ok Yun, Joo-Hang Kim. 1 Brain Korea 21 Project for Medical Science, Institute for Cancer Research, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea. Recent clinical trials with Herpes Simplex Virus Thymidine Kinase (HSV-TK) gene therapy using E1-deleted replication-incompetent adenovirus have shown encouraging results, but with limited efficacy. We have previously demonstrated that the cytolytic potency of replication-competent adenoviruses with different combination of E1B genes differed significantly depending on the presence or deletion of E1B 55kDa and E1B 19kDa function (Kim JS. et al. Cancer Gene Therapy). To combine the advantages of the suicide gene approach with that of replicating adenoviruses, we have developed replicating adenoviral vectors harboring HSV-TK, generating Ad-∆E1B19/55-TK, Ad-∆E1B19-TK, and Ad-∆E1B55TK adenoviruses. The cytotoxicity of the combination therapy with replicating adenoviruses (Ad-∆E1B55-TK or Ad-∆E1B19/55-TK) and GCV was dramatically increased compared with replicating adenoviruses alone or replication-incompetent adenovirus expressing HSV-TK (Ad-∆E1-TK) with GCV. In contrast, the cytotoxicity of the combination therapy with Ad-∆E1B19-TK and GCV was significantly reduced when compared to the treatment with Ad∆E1B19-TK alone. In addition, the total viral production of Ad∆E1B19-TK in the presence of GCV was significantly reduced. Taken together, these results suggest that the inhibition of viral replication by the HSV-TK/GCV system counterbalance the cytotoxicity of Ad-∆E1B19-TK. The human cervical cancer (C33A) and lung cancer (A549) xenograft models treated with replicationcompetent adenoviruses with GCV had more significant reduction in tumor growth compared to animals that were injected with PBS or Ad-∆E1-TK with GCV. In summary, these data indicate that the suicide gene approach with replicating adenoviruses elicits more enhanced anti-tumor effect than that with replication-incompetent adenovirus.

552. Gene Therapy of Uterine Fibroids: Adenovirus-Mediated Expression of Dominant Negative Estrogen Receptor Inhibits ERE-Reporter Transactivation in Rat and Human Leiomyoma Cells Ayman Al-Hendy.1 1 Obstetrics & Gynecology, University of Texas Medical branch, Galveston, TX. Introduction: Uterine leiomyomas (fibroids) are the most common tumors in premenopausal women. Currently there is no medicinal treatment for this condition and surgery is the main stay. This constitutes a clinical dilemma especially in young fibroid patients who desire to preserve their fertility. We have recently (Am J Obstetrics and Gynecology, 2004,191:00-00) demonstrated the ability of a mutated dominant-negative estrogen receptor gene delivered via an adenoviral vector (Ad-DN-ER) to induce apoptosis in leiomyoma cells as well as ablate pre-existing fibroids in vivo. Molecular Therapy Volume 11, Supplement 1, May 2005 Copyright  The American Society of Gene Therapy

Objective: To assess the mechanism of Ad-DN-ER-induced apoptosis in leiomyoma cells. Methods: As experimental models we used primary cultures of human leiomyoma cells (LM155) derived from fibroid tumors removed at hysterectomy as well as rat leiomyoma cells (ELT3). We also used a telomerase-immortalized human myometrial cell line (HM9). Adenovirus carrying two copies of the estrogen responsive element upstream of luciferase reporter (Ad-ERE-Luc) was used at 10-100 pfu/cell.To investigate the effect of Ad-DN-ER on EREreporter transactivation, cells were infected with the therapeutic viral vector for 48 hours. Luciferase expression was measured using standard methods. Results: In ELT3 rat leiomyoma cells, treatment with Ad-DNER at 10, 50, 100, and 200 pfu/cell induced a reduction of EREluciferase activity by 30%, 92%, 96% and 97% respectively (P