title: Antitumor activity of an oncolytic adenovirus-delivered oncogene small interfering RNA.
abstract: Despite successes in animal models, cancer gene therapy with small interfering RNAs (siRNA) is hindered by the lack of an optimal delivery platform. We examined the applicability of the replication-competent, oncolytic adenovirus, ONYX-411, to deliver a mutant K-ras siRNA transgene to human cancer cells. Proof-of-principle studies showed an additive tumor growth-inhibitory response through siRNA-mediated K-ras knockdown and ONYX-411-mediated cancer cell lysis. A novel construct, termed Internavec (for interfering RNA vector), was generated by cloning a K-ras(v12)-specific siRNA(ras-4) hairpin construct under the control of the human H1 promoter into the deleted E3b region of ONYX-411. Internavec acquired an increase in potency of approximately 10-fold in human cancer cells expressing the relevant K-ras(v12) mutation (H79, H441, and SW480), as defined by a reduction in the effective dose needed to achieve 50% growth inhibition (ED(50)). Internavec remained attenuated in nonmalignant epithelial cells. Daily intratumoral injections of Internavec (five daily injections of 1 x 10(8) plaque-forming units) significantly reduced the growth of s.c. H79 pancreatic cancer xenografts in nu/nu mice by 85.5%, including complete growth suppression in three of five mice. Parental ONYX-411 or ONYX-411-siRNA(GFP) was markedly less effective (47.8% growth reduction, P = 0.03; and 44.1% growth reduction, P = 0.03, respectively). siRNA(ras) transgene activity contributed to cell cycle blockage, increased apoptosis, and marked down-regulation of Ras signaling-related gene expression (AKT2, GSK3 beta, E2F2, and MAP4K5). These findings indicate that Internavec can generate a two-pronged attack on tumor cells through oncogene knockdown and viral oncolysis, resulting in a significantly enhanced antitumor outcome.
authors.affiliation: The Mary Crowley Medical Research Center, Dallas, Texas.
authors.forename: Yu-An
authors.initials: YA
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Nemunaitis
authors.forename: Shirley K
authors.initials: SK
authors.lastname: Samuel
authors.forename: Patrick
authors.initials: P
authors.lastname: Chen
authors.forename: Yuqiao
authors.initials: Y
authors.lastname: Shen
authors.forename: Alex W
authors.initials: AW
authors.lastname: Tong
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000628:therapy; D000256:Adenoviridae / Q000235:genetics* / Q000502:physiology; D000818:Animals; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology; D002455:Cell Division; D045744:Cell Line, Tumor / Q000187:drug effects; D003110:Colonic Neoplasms / Q000473:pathology; D004847:Epithelial Cells / Q000187:drug effects; D020869:Gene Expression Profiling; D011905:Genes, ras; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D015689:Oncogene Protein p21(ras) / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000628:therapy; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics* / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D034741:RNA, Small Interfering; D019908:Proto-Oncogene Proteins c-raf; D015689:Oncogene Protein p21(ras)