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EBV replicon vector system enhances transgene expression in vivo : applications to cancer gene therapy
Author(s) -
Otomo Takanobu,
Yamamoto Seiji,
Morishita Ryuichi,
Kaneda Yasufumi
Publication year - 2001
Publication title -
the journal of gene medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 91
eISSN - 1521-2254
pISSN - 1099-498X
DOI - 10.1002/jgm.199
Subject(s) - replicon , biology , genetic enhancement , luciferase , microbiology and biotechnology , transgene , viral vector , vector (molecular biology) , virology , suicide gene , cancer research , expression vector , gene , transfection , plasmid , genetics , recombinant dna
Abstract Background A major limitation of current cancer gene therapies is low and transient expression of the therapeutic gene. For long‐term expression of transgenes in vivo , an Epstein‐Barr virus (EBV) replicon vector has been developed. The present study examines the effect of the EBV replicon vector system and its application to a suicide gene therapy for melanoma in mice. Methods An EBV replicon vector system, pEBc, consisting of EBV nuclear antigen‐1 (EBNA‐1) and the origin of latent viral DNA replication, oriP, was used to express either the luciferase gene or the herpes simplex virus (HSV) thymidine kinase (TK) gene. The expression vector was introduced in vivo into melanoma tumor masses in mice by means of HVJ‐cationic liposomes. The time‐course of gene expression and the anticancer effect of the EBV replicon vector were investigated in comparison with pcLuc, which lacks the EBV components. Results Luciferase expression was sustained in both cultured cells and melanoma masses by pEBc but not by pcLuc. The luciferase expression level in melanoma masses was higher by pEBcLuc than by pcLuc, although Southern blot analysis showed the number of copies of pEBcLuc retained in the melanoma masses to be fewer than that of pcLuc. The effectiveness of EBV replicon vector on suicide gene therapy of melanoma in mice was also demonstrated. Conclusion The EBV replicon vector appears useful for cancer gene therapy. Analysis of the transgene in tumors suggests that the EBV replicon system may be responsible for efficient transcription but not retention of the transgene. Copyright © 2001 John Wiley & Sons, Ltd.