Fas Ligand Delivery by a Prostate-Restricted Replicative Adenovirus Enhances Safety and Antitumor Efficacy

• Published in: Clinical cancer research 2007-09, Vol.13 (18), p.5463-5473
• Main Authors: Li, Xiong, Liu, You-Hong, Zhang, Yan-Ping, Zhang, Shaobo, Pu, Xinzhu, Gardner, Thomas A, Jeng, Meei-Huey, Kao, Chinghai
• Format: Article
• Language: English
• Subjects: Adenoviridae - genetics; Adenovirus; Androgens - analysis; Androgens - metabolism; Animals; Antigens, Surface - analysis; Antigens, Surface - metabolism; Antineoplastic agents; Apoptosis; Biological and medical sciences; Cytomegalovirus; Cytoplasmic Vesicles - metabolism; Fas ligand; Fas Ligand Protein - genetics; gene therapy; Genetic Therapy; Genetic Vectors - genetics; Glutamate Carboxypeptidase II - analysis; Glutamate Carboxypeptidase II - metabolism; Humans; Male; Medical sciences; Mice; Pharmacology. Drug treatments; Prostate - chemistry; Prostate - metabolism; Prostate - pathology; prostate cancer; Prostate-Specific Antigen - analysis; Prostate-Specific Antigen - metabolism; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Prostatic Neoplasms - therapy; PRRA; PSA; PSMA; tissue-specific enhancer; Virus Replication; Xenograft Model Antitumor Assays
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-07-0342

Purpose: Recent studies showed that Fas ligand (FasL) induced apoptosis in tumor cells and suppressed the immune response in several types of tumors. However, the toxicity of FasL limited further administration. This study delivered FasL in prostate cancer cells using an improved prostate-restricted replicative adenovirus (PRRA), thereby improving the antitumor effect while decreasing systemic toxicity. Experimental Design: We designed a FasL-armed PRRA, called AdIU3, by placing adenoviral E1a and E4 genes, FasL cDNA, and E1b gene under the control of two individual PSES enhancers. Tissue-specific viral replication and FasL expression were analyzed, and the tumor killing effect of AdIU3 was investigated both in vitro and in vivo using androgen-independent CWR22rv s.c. models via local administration and bone models via systemic administration. The safety of systemic administration of AdIU3 was evaluated. AdCMVFasL, in which FasL was controlled by a universal cytomegalovirus (CMV) promoter, was used as a control. Results: AdIU3 enhanced FasL expression in prostate-specific antigen (PSA)/prostate-specific membrane antigen (PSMA)-positive cells but not in PSA/PMSA-negative cells. It induced apoptosis and killed PSA/PMSA-positive prostate cancer cells but spared normal human fibroblasts, hepatocytes, and negative cells. The increase in killing activity was confirmed to result in part from a bystander killing effect. Furthermore, AdIU3 was more effective than a plain PRRA in inhibiting the growth of androgen-independent prostate cancer xenografts and bone tumor formation. Importantly, systemic administration of AdIU3 resulted in undetectable toxicity, whereas the same doses of AdCMVFasL killed all mice due to multiviscera failure in 16 h. Conclusions: AdIU3 decreased the toxicity of FasL by controlling its expression with PSES, with greatly enhanced prostate cancer antitumor efficacy. The results suggested that toxic antitumor factors can be delivered safely by a PRRA.