Selective gene silencing by viral delivery of short hairpin RNA

Abstract

RNA interference (RNAi) technology has not only become a powerful tool for functional genomics, but also allows rapid drug target discovery and in vitro validation of these targets in cell culture. Furthermore, RNAi represents a promising novel therapeutic option for treating human diseases, in particular cancer. Selective gene silencing by RNAi can be achieved essentially by two nucleic acid based methods: i) cytoplasmic delivery of short double-stranded (ds) interfering RNA oligonucleotides (siRNA), where the gene silencing effect is only transient in nature, and possibly not suitable for all applications; or ii) nuclear delivery of gene expression cassettes that express short hairpin RNA (shRNA), which are processed like endogenous interfering RNA and lead to stable gene down-regulation. Both processes involve the use of nucleic acid based drugs, which are highly charged and do not cross cell membranes by free diffusion. Therefore, in vivo delivery of RNAi therapeutics must use technology that enables the RNAi therapeutic to traverse biological membrane barriers in vivo. Viruses and the vectors derived from them carry out precisely this task and have become a major delivery system for shRNA. Here, we summarize and compare different currently used viral delivery systems, give examples of in vivo applications, and indicate trends for new developments, such as replicating viruses for shRNA delivery to cancer cells.

Effective Transgene Constructs to Enhance Gene Therapy with Trichostatin A

“…For the expression of a specific transgene in desired cells or tissues with the proper timing, many vectors carrying transgenes have been developed (Mátrai et al, 2010;Nayak & Herzog, 2010;Sliva & Schnierle, 2010). Retroviral, lentiviral, adenoviral, and adeno-associated viral vectors are used in various ways to achieve these goals.…”

Combined RNA Interference of Hexokinase II and 131I-Sodium Iodide Symporter Gene Therapy for Anaplastic Thyroid Carcinoma

“…Contrary to siRNA, small hairpin RNA (shRNA) is integrated into chromosomal DNA and is constantly expressed to achieve prolonged gene silencing (13). The major advantage of the lentiviral shRNA system is that the shRNA can be delivered into both dividing and nondividing cells to achieve stable long-term effects on target gene silencing; therefore, it can be used for in vivo applications (14). Recently, many studies reported the use of retroviral-and lentiviral-based vector systems for the expression of shRNAs for cancer therapy (15,16).…”

BMP-2, Hypoxia, and COL1A1/HtrA1 siRNAs Favor Neo-Cartilage Hyaline Matrix Formation in Chondrocytes

“…36 However, the use of a viral vector and shRNA is known to induce stable knockdown, whereas siRNAs induce a transient knockdown. 37,38 Our experimental strategy was developed so as to avoid a gene therapy approach, and favor a cell therapy approach to cartilage repair, thereby avoiding the ethical problems behind genome modification. In addition, our study aimed first and foremost at decreasing the expression of type I collagen transiently to initiate the redifferentiation of dedifferentiated chondrocytes.…”