Potent antitumor activity in experimental hepatocellular carcinoma by adenovirus-mediated coexpression of TRAIL and shRNA against COX-2.
OBJECTIVE
Recent studies have indicated that short hairpin RNA (shRNA) driven by RNA polymerase (Pol) II promoters can be transcribed into precursor mRNAs together with transgenes. It remains unclear, however, whether coexpression of shRNA and transgene from a single promoter is feasible for cancer therapy.


METHODS
In this study, we generated novel adenoviral vectors that permitted coexpression of shRNA against cyclooxygenase-2 (COX-2) and the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) therapeutic gene from a cytomegalovirus promoter to evaluate whether silencing of COX-2 could increase the sensitivity of hepatocellular carcinoma to TRAIL.


RESULTS
Our data showed that adenovirus vector Ad-TM, in which the shRNA was inserted into the 3' untranslated region of the TRAIL gene, not only significantly suppressed COX-2 expression, but also expressed a high level of TRAIL. Moreover, infection with Ad-TM resulted in significant cytotoxicity in hepatocellular carcinoma cell lines. In contrast, it had no effect on normal liver cell line. Impressively, treatment of the established hepatocellular carcinoma tumors with Ad-TM resulted in complete tumor regression. This potent antitumor activity induced by Ad-TM was due to strong inhibition of COX-2 and high expression of TRAIL. Furthermore, using the shRNA and transgene coexpression adenovirus system, we showed that silencing of COX-2 increased the sensitivity of hepatocellular carcinoma to TRAIL through inhibition of Bcl-2 and Bcl-w.


CONCLUSIONS
This study indicated that adenovirus carrying shRNA and transgene expressed from a single promoter represented a potent approach for cancer therapy.
Chen
Qing
Q
Laboratory of Biotherapy of Cancer, Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University, Chongqing, China.
Lou
Wenjia
W
Shen
Junjie
J
Ma
Leina
L
Yang
Zhi
Z
Liu
Li
L
Luo
Jingjing
J
Qian
Cheng
C
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000628:therapy*; D049109:Cell Proliferation; D051546:Cyclooxygenase 2 / Q000096:biosynthesis / Q000235:genetics*; D004195:Disease Models, Animal; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000628:therapy*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011401:Promoter Regions, Genetic / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics / Q000627:therapeutic use*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D051017:Apoptosis Regulatory Proteins; C491073:BCL2L2 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human