title: Antitumor Effects of Oncolytic Adenovirus-Carrying siRNA Targeting Potential Oncogene EphA3.
abstract: Conditionally replicating adenoviruses (CRAds) armed with antitumor transgenes hold promise for cancer treatment. In previous studies, we showed that the 1504-siRNA targeting potential oncogene EphA3 was an efficient therapeutic transgene and that the telomerase reverse transcriptase promoter (TERTp) driving the CRAd was a more advanced generation of CRAd. Therefore, we combined Ad-TERTp-E1A-1504 by inserting 1504-siRNA into the CRAd to study its antitumor effects and mechanism of action, using Ad-TERTp-E1A-NC and nonreplicating adenovirus carrying 1504-siRNA as controls. Cell viability assays and ED50 studies of growth inhibition confirmed that Ad-TERTp-E1A-1504 has 3.5- and 1,400-fold greater ability to kill EphA3- and TERT-expressing tumor cells compared to Ad-TERTp-E1A-NC and Ad-ΔE1A-1504, respectively. Also, Ad-TERTp-E1A-1504 had little effect on cells that modestly expressed EphA3 and TERT such as 2BS. The antitumor efficacy of Ad-TERTp-E1A-1504 was also validated in vivo. Furthermore, the virus yield of Ad-TERTp-E1A-1504 in C4-2B was ~1,000 times greater than that in 2BS. No obvious differences were observed between Ad-TERTp-E1A-1504 and Ad-TERTp-E1A-NC. Both acridine orange staining and Beclin1 protein measurements indicated that autophagy with Ad-TERTp-E1A-1504 at 5 and 10 MOI was higher than that of Ad-TERTp-E1A-NC. Finally, the classical negatively regulated autophagy signaling pathway, PI3K/AKT/mTOR, was suppressed (reduced phosphorylated form) in contrast to NC, and that this was mediated by 1504-siRNA. Thus, Ad- TERTp-E1A-1504 does not harm normal cells but has dual inhibiting and killing effects on TERT- and EphA3-positive tumor cells, and this effect is mediated by the AKT/mTOR signaling pathway via induction of autophagy. These data may offer a foundation for novel antitumor therapies targeting this mechanism.
authors.affiliation: Astronaut Research and Training Center of China, Beijing, P. R. China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China; Southern Medical University, Guangzhou, P. R. China.
authors.forename: Hailiang
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China.
authors.forename: Ruiqin
authors.initials: R
authors.lastname: Wu
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China.
authors.forename: Shanhu
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Beijing, P. R. China.
authors.forename: Jianguang
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D045325:HCT116 Cells; D019073:HT29 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D050130:Oncolytic Virotherapy / Q000379:methods*; D050504:Oncolytic Viruses / Q000235:genetics* / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D036121:Receptor, EphA3; D023041:Xenograft Model Antitumor Assays
chemical_list: D034741:RNA, Small Interfering; C491718:EPHA3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D036121:Receptor, EphA3