This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zabala, M. Articles by Kramer, M. G. Search for Related Content PubMed PubMed Citation Articles by Zabala, M. Articles by Kramer, M. G.

Optimization of the Tet-on System To Regulate Interleukin 12 Expression in the Liver for the Treatment of Hepatic Tumors

¹ Division of Hepatology and Gene Therapy, School of Medicine, Fundacion para la Investigacion Medica Aplicada (FIMA), University of Navarra, Pamplona, Spain; ² Jilin University, Department of Pathology, Changchun, China; and ³ Institüt für Mikrobiologie, Biochemie und Genetik, Friedrich-Alexander Universität, Erlangen-Nurnberg, Germany

Interleukin 12 (IL-12) is a potent antitumoral cytokine, but it can be toxic at high doses. Therapy of liver tumors might benefit from the use of vectors enabling tight control of IL-12 expression in hepatic tissue for long periods of time. To this aim, we have improved the Tet-on system by modifying the minimal region of the inducible promoter and adjusting the level of the trans-activator using liver-specific promoters with graded activities. The resulting vectors allowed hepato-specific gene regulation with lower basal activity and higher inducibility compared with the original system in the absence of repressor molecules. The basal and final protein levels depend on the strength of the promoter that directs the transcripcional activator as well as the relative orientation of the two genes in the same plasmid. We have selected the construct combining minimal leakage with higher level of induced gene expression to regulate IL-12 after DNA transfer to mouse liver. Administration of doxycycline (Dox) enhanced IL-12 expression in a dose-dependent manner, whereas it was undetectable in serum in the noninduced state. Gene activation could be repeated several times, and sustained levels of IL-12 were achieved by daily administration of Dox. The antitumor effect of IL-12 was evaluated in a mouse model of metastatic colon cancer to the liver. Complete eradication of liver metastasis and prolonged survival was observed in all mice receiving Dox for 10 days. These data demonstrate the potential of a naked DNA gene therapy strategy to achieve tight control of IL-12 within the liver for the treatment of cancer.

This article has been cited by other articles:

				S. Huard, R. T. Elder, D. Liang, G. Li, and R. Y. Zhao Human Immunodeficiency Virus Type 1 Vpr Induces Cell Cycle G2 Arrest through Srk1/MK2-Mediated Phosphorylation of Cdc25 J. Virol., March 15, 2008; 82(6): 2904 - 2917. [Abstract] [Full Text] [PDF]

				D. W. Nebert Comparison of gene expression in cell culture to that in the intact animal: relevance to drugs and environmental toxicants. Focus on "Development of a transactivator in hepatoma cells that allows expression of phase I, phase II, and chemical defense genes" Am J Physiol Cell Physiol, January 1, 2006; 290(1): C37 - C41. [Full Text] [PDF]

				C. E. P. Goldring, N. R. Kitteringham, R. Jenkins, C. A. Lovatt, L. E. Randle, A. Abdullah, A. Owen, X. Liu, P. J. Butler, D. P. Williams, et al. Development of a transactivator in hepatoma cells that allows expression of phase I, phase II, and chemical defense genes Am J Physiol Cell Physiol, January 1, 2006; 290(1): C104 - C115. [Abstract] [Full Text] [PDF]