Cancer-specific targeting of a conditionally replicative adenovirus using mRNA translational control.
BACKGROUND
In view of the limited success of available treatment modalities for a wide array of cancer, alternative and complementary therapeutic strategies need to be developed. Virotherapy employing conditionally replicative adenoviruses (CRAds) represents a promising targeted intervention relevant to a wide array of neoplastic diseases. Critical to the realization of an acceptable therapeutic index using virotherapy in clinical trials is the achievement of oncolytic replication in tumor cells, while avoiding non-specific replication in normal tissues. In this report, we exploited cancer-specific control of mRNA translation initiation in order to achieve enhanced replicative specificity of CRAd virotherapy agents. Heretofore, the achievement of replicative specificity of CRAd agents has been accomplished either by viral genome deletions or incorporation of tumor selective promoters. In contrast, control of mRNA translation has not been exploited for the design of tumor specific replicating viruses to date. We show herein, the utility of a novel approach that combines both transcriptional and translational regulation strategies for the key goal of replicative specificity.


METHODS
We describe the construction of a CRAd with cancer specific gene transcriptional control using the CXCR4 gene promoter (TSP) and cancer specific mRNA translational control using a 5'-untranslated region (5'-UTR) element from the FGF-2 (Fibroblast Growth Factor-2) mRNA.


RESULTS
Both in vitro and in vivo studies demonstrated that our CRAd agent retains anti-tumor potency. Importantly, assessment of replicative specificity using stringent tumor and non-tumor tissue slice systems demonstrated significant improvement in tumor selectivity.


CONCLUSIONS
Our study addresses a conceptually new paradigm: dual targeting of transgene expression to cancer cells using both transcriptional and mRNA translational control. Our novel approach addresses the key issue of replicative specificity and can potentially be generalized to a wide array of tumor types, whereby tumor selective patterns of gene expression and mRNA translational control can be exploited.
Stoff-Khalili
Mariam A
MA
Division of Human Gene Therapy, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294-2172, USA.
Rivera
Angel A
AA
Nedeljkovic-Kurepa
Ana
A
DeBenedetti
Arrigo
A
Li
Xiao-Lin
XL
Odaka
Yoshinobu
Y
Podduturi
Jagat
J
Sibley
Don A
DA
Siegal
Gene P
GP
Stoff
Alexander
A
Young
Scott
S
Zhu
Zheng B
ZB
Curiel
David T
DT
Mathis
J Michael
JM
D020121:5' Untranslated Regions / Q000235:genetics; D000256:Adenoviridae / Q000235:genetics*; D017500:Adenovirus E1A Proteins / Q000235:genetics; D000818:Animals; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000628:therapy*; D050881:E1A-Associated p300 Protein / Q000235:genetics; D005260:Female; D005346:Fibroblast Growth Factors / Q000235:genetics; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D050130:Oncolytic Virotherapy / Q000379:methods*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis*; D019718:Receptors, CXCR4 / Q000235:genetics; D014158:Transcription, Genetic; D014779:Virus Replication
D020121:5' Untranslated Regions; D017500:Adenovirus E1A Proteins; D012333:RNA, Messenger; D019718:Receptors, CXCR4; D005346:Fibroblast Growth Factors; D050881:E1A-Associated p300 Protein