Antitumor effects of systemically delivered adenovirus harboring trans-splicing ribozyme in intrahepatic colon cancer mouse model.
OBJECTIVE
Our previous studies suggested that human telomerase reverse transcriptase (hTERT) RNA-targeting trans-splicing ribozyme could be a useful tool for cancer gene therapy. Here, we investigated whether adenoviruses harboring this ribozyme can be systemically delivered to mice, and whether they selectively mark tumors expressing hTERT and sensitize them to ganciclovir treatments.


METHODS
We constructed adenoviral vectors containing modified hTERT-targeting trans-splicing ribozyme with downstream reporter gene (Ad-Ribo-LacZ) or suicide gene (Ad-Ribo-HSVtk) driven by a cytomegalovirus promoter. The tumor-specific trans-splicing reaction and the tumor-killing effect of adenoviruses harboring ribozyme were investigated both in vitro and in vivo using mice with intrahepatic colon cancer metastasis via systemic administration. The safety of systemic administration of the viruses was also evaluated.


RESULTS
We showed that Ad-Ribo-LacZ, when injected i.v., performs a highly specific trans-splicing reaction on hTERT mRNA and that it selectively marks tumors expressing hTERT in mice. More importantly, i.v. injection of Ad-Ribo-HSVtk plus ganciclovir significantly reduced tumor burden, with minimal liver toxicity, in mice with metastatic liver cancer, compared with the untreated group (P = 0.0009). Moreover, animals receiving Ad-Ribo-HSVtk showed improved survival compared with controls (P < 0.0001).


CONCLUSIONS
This study shows that systemically delivered adenovirus harboring trans-splicing ribozyme can recognize cancer-specific transcripts and reprogram them to combat the cancer cells. Use of trans-splicing ribozymes seems to be a potentially useful gene therapy for cancer.
Jeong
Jin-Sook
JS
Department of Pathology and Medical Research Center for Cancer Molecular Therapy, Dong-A University College of Medicine, Busan, Korea.
Lee
Seong-Wook
SW
Hong
Seung-Hee
SH
Lee
Yoon-Jong
YJ
Jung
Haeng-Im
HI
Cho
Kyung-Sook
KS
Seo
Hye-Hyun
HH
Lee
Sang-Jin
SJ
Park
Sohee
S
Song
Min-Sun
MS
Kim
Chang-Min
CM
Kim
In-Hoo
IH
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D003110:Colonic Neoplasms / Q000473:pathology*; D004195:Disease Models, Animal; D005260:Female; D017930:Genes, Reporter; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology / Q000556:secondary / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D016337:RNA, Catalytic / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D020040:Trans-Splicing
D016337:RNA, Catalytic; D012333:RNA, Messenger; D019098:Telomerase