All-trans retinoic acid increases transgene expression in MSCV-transduced cells, via a mechanism that is retinoid receptor dependent but independent of cellular differentiation.
Treatment of MSCV-GFP-transduced HL60 promyelocytic cells with all-trans retinoic acid (ATRA) resulted in a significant increase in GFP expression. The increased GFP expression was observed by 16 hr and was dependent on de novo protein production. This effect was specific to ATRA and unrelated to cell differentiation because it was not induced by dimethyl sulfoxide. Furthermore, a similar increase in GFP expression was observed in MSCV-GFP-transfected K562 cells, which do not differentiate when exposed to ATRA. Significantly increased GFP expression was seen at doses as low as 0.5 nM ATRA and was abrogated by AGN193109, an antagonist of retinoid signaling. We therefore conclude that this increase in gene expression is mediated by retinoic acid receptors. The long terminal repeat (LTR) region of MSCV contains candidate retinoic acid response elements and response elements for the ATRA-inducible transcription factor C/EBPalpha. We suggest that the increase in GFP expression is driven by the action of ATRA-activated host cell transcription factors. These findings offer a method to increase the expression of retroviral transgenes either in vitro or in vivo by treatment with low doses of retinoic acid that are clinically achievable and well tolerated. This use of inducible host cell transcription factors offers an alternative to engineering novel LTR regulatory sequences in order to increase transgene expression.
Mountford
Joanne C
JC
Section of Experimental Haematology and Haemopoietic Stem Cells, Division of Cancer Sciences, University of Glasgow, Glasgow Royal Infirmary, Glasgow G31 2ER, United Kingdom. jcm7n@clinmed.gla.ac.uk
Vanin
Elio F
EF
Hayden
Rachel E
RE
Bunce
Christopher M
CM
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001483:Base Sequence; D002454:Cell Differentiation; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D009052:Leukemia Virus, Murine / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009281:Naphthalenes / Q000494:pharmacology; D018168:Receptors, Retinoic Acid / Q000037:antagonists & inhibitors / Q000378:metabolism; D013234:Stem Cells / Q000821:virology; D014157:Transcription Factors; D014161:Transduction, Genetic; D019076:Transgenes / Q000502:physiology*; D014212:Tretinoin / Q000494:pharmacology*; D014759:Viral Envelope Proteins / Q000235:genetics
D000970:Antineoplastic Agents; C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D009281:Naphthalenes; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; D014759:Viral Envelope Proteins; D049452:Green Fluorescent Proteins; D014212:Tretinoin; C096920:AGN 193109