Poor intercellular transport and absence of enhanced antiproliferative activity after non-viral gene transfer of VP22-P53 or P53-VP22 fusions into p53 null cell lines in vitro or in vivo.
BACKGROUND
The herpes simplex virus type 1 (HSV-1) VP22 protein has the property to mediate intercellular trafficking of heterologous proteins fused to its C- or N-terminus. We have previously shown improved delivery and enhanced therapeutic effect in vitro and in vivo with a P27-VP22 fusion protein. In this report, we were interested in studying the spread and biological activity of VP22 fused to the P53 tumor suppressor.


METHODS
Expression of the VP22-P53 and P53-VP22 fusion proteins was shown by Western blot and intercellular spreading was monitored by immunofluorescence on transiently transfected cells. In vitro antiproliferative activity of wild-type (wt) P53 and P53-VP22 was assessed by proliferation assays and transactivating ability was studied by a reporter gene test and a gel-shift assay. Antitumor activity was also tested in vivo by intratumoral injections of naked DNA in a model of subcutaneous tumors implanted in nude mice.


RESULTS
Our results show that the C-terminal fusion or the N-terminal P53-VP22 fusion proteins are not able to spread as efficiently as VP22. Moreover, we demonstrate that VP22-P53 does not possess any transactivating ability. P53-VP22 has an antiproliferative activity, but this activity is not superior to the one of P53 alone, in vitro or in vivo.


CONCLUSIONS
Our study indicates that a gene transfer strategy using VP22 cannot be considered as a universal system to improve the delivery of any protein.
Zavaglia
David
D
Groupe de Recherche sur le Cancer du Poumon, INSERM U578, Institut Albert Bonniot, 38706 La Tronche, France.
Lin
Erh-Hsuan
EH
Guidetti
Mélanie
M
Pluquet
Olivier
O
Hainaut
Pierre
P
Favrot
Marie-Christine
MC
Coll
Jean-Luc
JL
D000818:Animals; D019677:Artificial Gene Fusion; D049109:Cell Proliferation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005822:Genetic Vectors; D051379:Mice; D008819:Mice, Nude; D021381:Protein Transport / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D015678:Viral Structural Proteins / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D015678:Viral Structural Proteins; C073413:herpes simplex virus type 1 protein VP22