• BMB Reports
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• v.41 no.10
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• pp.716-721
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• 2008

To explore the effects of deregulated expression of the EBNA1 binding protein 2 (EBP2) on cell growth, we generated human HEK293 stable clones constitutively expressing an EBP2-EGFP fusion protein. We found both RNA and protein levels of cyclin E1, a dominant oncoprotein, were elevated in the EBP2- EGFP stable clones. These findings were confirmed by flow cytometry bivariate analysis of cyclin expression versus DNA content. Moreover, the increase in p21 expression and the specific phosphorylation at Ser1981 of ATM and Ser15 of p53 were also observed in these stable clones, and these observations may explain the failure to observe an increase in Cdk2 kinase activity. In addition, after one year of passage culture, the EBP2-EGFP stable clones tended to lose 4 to 5 chromosomes per cell when compared to that of control cells. All of these findings provide a possible link between deregulated expression of EBP2 and tumor development.

• Journal of Pharmaceutical Investigation
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• v.33 no.4
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• pp.267-272
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• 2003

Herpes simplex virus (HSV) thymidine kinase (TK) has been widely used for suicidal gene therapy in combination with nucleoside analogs such as ganciclovir (GCV). The use of HSV-TK is limited due to the side effect of GCV at high concentrations. Previous studies showed that stable transfectants of mutant HSV-TK with enhanced affinity to GCV were killed at lower GCV concentrations. In this study, we tested whether mutant HSV-TK can provide enhanced suicidal effect when transiently transfected with Epstein-Barr virus (EBV)-based plasmid. EBV-based plasmid which contains OriP and EBNA-1 sequence is well known for a stable episomal maintenance in human cells. Optimal transfection condition was assessed for SNU-638 gastric cancer cell line using polyetylnimine (PEI). Maximum transfection efficiency was achieved when DNA:PEI was 1:3 (w/v). Cytotoxicities of mutant and wild type HSV-TK were compared before and after partially selecting transfected cells. The cells were sensitive to $100\;{\mu}g/ml$ hygromycin. Following GCV treatment, more cells were killed after hygromycin selection than before selection. The mutant HSV-TK showed enhanced cytotoxicity compared with the wild type HSV-TK. Our results suggest that the EBV-based plasmid encoding mutant HSV-TK may be useful to treat the diseases caused by uncontrolled cell proliferation such as cancer and rheumatoid arthritis.