Fas ligand delivery by a prostate-restricted replicative adenovirus enhances safety and antitumor efficacy.
OBJECTIVE
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.


METHODS
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.
Li
Xiong
X
Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA..
Liu
You-Hong
YH
Zhang
Yan-Ping
YP
Zhang
Shaobo
S
Pu
Xinzhu
X
Gardner
Thomas A
TA
Jeng
Meei-Huey
MH
Kao
Chinghai
C
D000256:Adenoviridae / Q000235:genetics*; D000728:Androgens / Q000032:analysis / Q000378:metabolism; D000818:Animals; D000954:Antigens, Surface / Q000032:analysis / Q000378:metabolism; D017209:Apoptosis; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D053222:Fas Ligand Protein / Q000235:genetics*; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics*; D043425:Glutamate Carboxypeptidase II / Q000032:analysis / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D011467:Prostate / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000032:analysis / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D014779:Virus Replication; D023041:Xenograft Model Antitumor Assays
D000728:Androgens; D000954:Antigens, Surface; D053222:Fas Ligand Protein; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II; D017430:Prostate-Specific Antigen