Novel amplifier expression vectors producing higher levels of IL-2 led to slower tumor growth and longer survival in vivo.
Sufficient levels of gene expression are required for effective gene therapy. One of the major obstacles in gene therapy is the low transgene expression obtained from currently available vector systems. To address this issue, we employed a transcriptional amplifier strategy in a single construct to enhance transgene expression. In the amplifier vectors (pHi-1 and pHi-2), the strong CMV promoter was used to drive a transcriptional factor, Tat, which could transactivate a second promoter (HIV1 LTR or HIV2 LTR) located in the same construct driving the gene of interest. Using the human interleukin-2 (IL-2) cytokine gene, our data showed that the pHi-1/2 amplifier vectors could produce significantly higher IL-2 levels in human lung cancer cells (A549) and breast cancer cells (MCF-7) than that obtained by directly using the CMV promoter alone. Injection of pHi-2-IL-2-modified Lewis Lung (LL/2) tumor clones led to significantly slower tumor growth and longer survival in mice compared to those injected with either CMV promoter driven IL-2 clones or the parental tumor cells. Our results demonstrated that the transcriptional amplifier-based expression cassettes could be very useful in applications where high levels of gene expression are difficult to achieve.
Luo
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Gene Therapy Group, Department of Microbiology and Immunology, University of Arizona, Tucson, 85724, USA. phoebeluo2000@yahoo.com
Tsang
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TC
He
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Gonzalez-Pena
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Jaramillo
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Takeuchi
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Harris
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D000818:Animals; D045744:Cell Line, Tumor; D003587:Cytomegalovirus; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics*; D049452:Green Fluorescent Proteins; D016325:HIV Long Terminal Repeat / Q000235:genetics; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics / Q000378:metabolism*; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000628:therapy*; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D019076:Transgenes / Q000235:genetics
D007376:Interleukin-2; D014157:Transcription Factors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins