Intercellular delivery of thymidine kinase prodrug activating enzyme by the herpes simplex virus protein, VP22

Abstract

We demonstrate that fusion proteins consisting of the her-COS cells transfected with tk alone. Tumours established pes simplex virus (HSV) transport protein VP22 linked in in mice with neuroblastoma cell lines expressing VP22-tk frame to HSV thymidine kinase (tk) retain the ability to be regressed upon administration of ganciclovir. Furthermore transported between cells. In vivo radiolabelling experitumours established from 50:50 mixtures of VP22-tk transments and in vitro assays show that the fusion proteins duced and nontransduced cells also regressed while no also retain tk activity. When transfected COS cells, acting significant effect was observed in similar experiments with as a source of the VP22-tk chimera, were co-plated on to cells transduced with tk alone. VP22 mediated transport gap junction-negative neuroblastoma cells, ganciclovir may thus have application in a clinical setting to amplify treatment induced efficient cell death in the recipient neurodelivery of the target protein in enzyme-prodrug protocols. blastoma cell monolayer. No such effect was observed with

Fusogenic membrane glycoproteins induce syncytia formation and death in vitro and in vivo: a potential therapy agent for lung cancer

“…29 Fusion proteins between VP22 and a therapeutic polypeptide were thus successfully used for in vivo tumor therapy although conflicting results have also been reported. 27,28,[30][31][32][33][34][35] Positive gene therapy results using suicide genes like the herpes simplex type-1 thymidine …”

Enhanced suicide gene effect by adenoviral transduction of a VP22-cytosine deaminase (CD) fusion gene

“…23 VP22 fusion proteins were also found to retain this activity of intercellular protein transport, as exemplified after transfection of the fusion proteins VP22-GFP, [23][24][25] VP22-p53, 26 and VP22-tk. 27 Additionally, the VP22-p53 and VP22-tk fusions demonstrated enhanced therapeutic effects when compared with the unfused versions of the enzymes. 26,27 We could show, that transport of VP22 cargo proteins is a general biological phenomenon, not restricted to distinct tissues or organs.…”

“…27 Additionally, the VP22-p53 and VP22-tk fusions demonstrated enhanced therapeutic effects when compared with the unfused versions of the enzymes. 26,27 We could show, that transport of VP22 cargo proteins is a general biological phenomenon, not restricted to distinct tissues or organs. 25 To overcome the limiting primary transduction rates of gene transfer vectors, we investigated whether chimaeric fusions, consisting of HSV-1 VP22 and E. coli CD, retain their transport property in recombinant adenoviruses and exhibit an enhanced suicide gene effect.…”

Direct evidence for the absence of intercellular trafficking of VP22 fused to GFP or to the herpes simplex virus thymidine kinase

“…26,36 A very different type of BE that is independent of the level of connexins has been recently reported. 37,38 In this case, it is not the GCV metabolites but the TK enzyme that diffuses from TK positive cells toward neighboring untransduced cells. This was made possible by fusing TK to VP22 (TK/VP22), another herpes simplex virus protein that has the ability to translocate between cells.…”

“…39 This property of VP22 was first demonstrated with the protein alone or fused to GFP, and it was then extended to other fusion partners that have a therapeutic potential in gene therapy. 37,38,[40][41][42][43] Using this very attractive strategy, an increase in the BE was reported with TK/ VP22 versus TK alone; however, the cytotoxic effect enhancement was very limited, 37,38 and it was only detected when a high percentage of cells expressed the fusion protein. 37 Based on these results, we hypothesized that TK30 fused to VP22 should increase the BE independently of the level of connexins.…”