title: Targeting tumor gene by shRNA-expressing Salmonella-mediated RNAi.
abstract: RNA interference (RNAi) has been established as an important research tool that carries great potential for gene therapy. However, targeted induction of RNAi in vivo has met with significant challenges. In this study, a novel pSLS plasmid capable of expressing short hairpin RNAs (shRNAs) was transformed into attenuated Salmonella enterica serovar typhimurium strain 7207 (SL). In vitro infection studies with the transformed S. enterica containing pSLS (SL-pSLS-CAT) demonstrated that expression of shRNA targeting the CTNNB1 gene induced potent and specific silencing of CTNNB1 expression in cultured SW480 cells. CTNNB1 knockdown in SW480 cells was associated with markedly reduced proliferation and cell death compared with that of control infected cells. In addition, SL-pSLS-CAT-mediated CTNNB1 knockdown markedly reduced tumor growth in SW480 xenograft mice. These tumors exhibited reduced levels of CTNNB1, as well as c-Myc and cyclin D1. Finally, SL-pSLS-CAT treatment also resulted in reduced expression levels of these genes in polyps, mucosal tissues and in small intestines of APC(Min) mice. Taken together, these data suggest that attenuated shRNA-expressing Salmonella may be a powerful new tool for in vitro gene silencing, functional genomics, and the development of RNAi-based anticancer or human immunodeficiency virus therapeutics.
authors.affiliation: Skip Ackerman Center for Molecular Therapeutics, Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. guohn2000@gmail.com
authors.forename: H
authors.initials: H
authors.lastname: Guo
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: C
authors.initials: C
authors.lastname: Inal
authors.forename: T
authors.initials: T
authors.lastname: Nguyen
authors.forename: J H
authors.initials: JH
authors.lastname: Fruehauf
authors.forename: A C
authors.initials: AC
authors.lastname: Keates
authors.forename: C J
authors.initials: CJ
authors.lastname: Li
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D020868:Gene Silencing; D018390:Gene Targeting; D052138:Genes, Neoplasm; D005822:Genetic Vectors / Q000235:genetics; D051379:Mice; D009369:Neoplasms / Q000235:genetics / Q000628:therapy*; D034622:RNA Interference; D012329:RNA, Bacterial / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D012475:Salmonella / Q000235:genetics* / Q000378:metabolism; D051176:beta Catenin / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: C495270:CTNNB1 protein, human; D012329:RNA, Bacterial; D034741:RNA, Small Interfering; D051176:beta Catenin