title: Transcriptional enhancers induce insertional gene deregulation independently from the vector type and design.
abstract: The integration characteristics of retroviral (RV) vectors increase the probability of interfering with the regulation of cellular genes, and account for a tangible risk of insertional mutagenesis in treated patients. To assess the potential genotoxic risk of conventional or self-inactivating (SIN) gamma-RV and lentiviral (LV) vectors independently from the biological consequences of the insertion event, we developed a quantitative assay based on real-time reverse transcriptase--PCR on low-density arrays to evaluate alterations of gene expression in individual primary T-cell clones. We show that the Moloney leukemia virus long terminal repeat (LTR) enhancer has the strongest activity in both a gamma-RV and a LV vector context, while an internal cellular promoter induces deregulation of gene expression less frequently, at a shorter range and to a lower extent in both vector types. Downregulation of gene expression was observed only in the context of LV vectors. This study indicates that insertional gene activation is determined by the characteristics of the transcriptional regulatory elements carried by the vector, and is largely independent from the vector type or design.
authors.affiliation: Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Giulietta
authors.initials: G
authors.lastname: Maruggi
authors.forename: Simona
authors.initials: S
authors.lastname: Porcellini
authors.forename: Giulia
authors.initials: G
authors.lastname: Facchini
authors.forename: Serena K
authors.initials: SK
authors.lastname: Perna
authors.forename: Claudia
authors.initials: C
authors.lastname: Cattoglio
authors.forename: Daniela
authors.initials: D
authors.lastname: Sartori
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ambrosi
authors.forename: Axel
authors.initials: A
authors.lastname: Schambach
authors.forename: Christopher
authors.initials: C
authors.lastname: Baum
authors.forename: Chiara
authors.initials: C
authors.lastname: Bonini
authors.forename: Chiara
authors.initials: C
authors.lastname: Bovolenta
authors.forename: Fulvio
authors.initials: F
authors.lastname: Mavilio
authors.forename: Alessandra
authors.initials: A
authors.lastname: Recchia
mesh_terms: D004742:Enhancer Elements, Genetic / Q000235:genetics* / Q000502:physiology; D005822:Genetic Vectors / Q000235:genetics*; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D008979:Moloney murine leukemia virus / Q000235:genetics; D016254:Mutagenesis, Insertional / Q000235:genetics*; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020079:Terminal Repeat Sequences / Q000235:genetics / Q000502:physiology