Combinatorial Control of Suicide Gene Expression by Tissue-specific Promoter and microRNA Regulation for Cancer Therapy

Abstract

Transcriptional targeting using a tissue-specific cellular promoter is proving to be a powerful means for restricting transgene expression in targeted tissues. In the context of cancer suicide gene therapy, this approach may lead to cytotoxic effects in both cancer and nontarget normal cells. Considering microRNA (miRNA) function in post-transcriptional regulation of gene expression, we have developed a viral vector platform combining cellular promoter-based transcriptional targeting with miRNA regulation for a glioma suicide gene therapy in the mouse brain. The therapy employed, in a single baculoviral vector, a glial fibrillary acidic protein (GFAP) gene promoter and the repeated target sequences of three miRNAs that are enriched in astrocytes but downregulated in glioblastoma cells to control the expression of the herpes simplex virus thymidine kinase (HSVtk) gene. This resulted in significantly improved in vivo selectivity over the use of a control vector without miRNA regulation, enabling effective elimination of human glioma xenografts while producing negligible toxic effects on normal astrocytes. Thus, incorporating miRNA regulation into a transcriptional targeting vector adds an extra layer of security to prevent off-target transgene expression and should be useful for the development of gene delivery vectors with high targeting specificity for cancer therapy.

MicroRNA-132 targets PEA-15 and suppresses the progression of astrocytoma in vitro

“…Recent studies show that the dysregulation of miR-132 is related to a variety of human tumors, such as non-small cell lung cancer (NSCLC), osteosarcoma, breast cancer, hepatocellular carcinoma, prostate cancer, gastric cancer, and pancreatic cancer [15][16][17][18][19][20][21]. Previous studies found that the expression of miR-132 was down-regulated in human glioblastomas [22,23]. Wang et al reported that overexpression of miR-132 inhibited…”

A pH-Sensitive Heparin-Binding Sequence from Baculovirus gp64 Protein Is Important for Binding to Mammalian Cells but Not to Sf9 Insect Cells

“…After packing its doublestranded DNA genome into a rod-shaped nucleocapsid, the budded virus (BV) is released from the infected insect cells with gp64 glycoprotein forming peplomers at one end of the virus particle (2,29,39). In recent years, BV has also been exploited for gene therapy applications, as it can efficiently transduce many types of mammalian cells with little cytotoxicity (21,45,47,49). Heparan sulfate, the highly negatively charged polysaccharide on the surface of mammalian cells, serves as the major binding molecule during baculovirus transduction (9).…”

Adaptive Immune Responses Elicited by Baculovirus and Impacts on Subsequent Transgene Expression In Vivo

“…These attributes have prompted the development of BV vectors for in vitro and in vivo gene delivery (3), RNA interference (4), cell-based assay development (5), production of viral vectors (6) and recombinant proteins (7), as well as cartilage and bone tissue engineering (8). Beyond these applications, BV is also used as an expression vector for the treatment of various cancers, including hepatoma (9), melanoma (10), colon cancer (11), brain cancer (12)(13)(14)(15)(16), prostate cancer (17,18), and ovarian cancer (17). In addition, BV has been explosively developed as a vaccine expression/display vector against a variety of pathogens, including avian influenza virus (AIV) (19)(20)(21)(22), avian reovirus (23), pseudorabies virus (24), enterovirus 71 (25), Plasmodium berghei (26), and many others (for a review, see reference 1).…”