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.

Correlative Gene Expression to Protective Seroconversion in Rift Valley Fever Vaccinates

“…The GRN method used a Bayesian model consensus scheme employing the Markov Chain Monte Carlo (MCMC) Metropolis-Hastings algorithm. It incorporates a gene expression data-derived proposal matrix and a priori probability distribution method for combining prior biological knowledge from multiple sources that included KEGG [ 37 ], REACTOME [ 62 ], BioGRID [ 8 ], DIP [ 63 ], IntAct [ 64 ], MINT [ 65 ], GO, and predicted and known transcription factors (TF) binding sites from TRANSFAC [ 66 ] and JASPER [ 67 ]. For the second step, the output of the GRN provided a unique approach to identifying high probability relationships between the highly correlated genes and other upstream and downstream genes.…”

Combined prokaryotic–eukaryotic delivery and expression of therapeutic factors through a primed autocatalytic positive-feedback loop

“…3 D and E), suggesting that it is considered safe enough for therapeutic uses. In addition, our system is superior to previous bacterial systems in term of in vivo stability [12,13]. Firstly, the bacterial factors involved in tumor fitness, intracellular delivery and expression were integrated into the chromosome.…”

“…Their low cost, fast production, diverse natural and modified tropism profiles, high packaging capacity, coupled with their relative tolerance of the immune system and relative ease of control in the case of adverse events, make bacterial-mediated delivery an attractive alternative for gastrointestinal [1], respiratory [2], urogenital tracts [3] and solid tumors [4,5]. Most studies use attenuated bacteria in some way to decrease virulence [6][7][8] and augment their natural cytotoxicity with vectors designed to deliver an agent to the target organs [9][10][11][12][13][14][15]. However, to date, clinical trials of bacterial mediated therapy have had modest results [5,16].…”

Salmonella-Mediated Cancer Therapy: Roles and Potential

“…Although some of these organisms are used as monotherapy [6,8,24], most of them are used as vehicles to deliver therapeutic agents such as DNA [19], siRNA [9,28], toxins [7, 10-12, 20, 30], and prodrug-enzymes [13], or combined with other therapies [14,15,21,32] to enhance their therapeutic effect.…”