Transduction of Fetal Mice With a Feline Lentiviral Vector Induces Liver Tumors Which Exhibit an E2F Activation Signature

Abstract

Lentiviral vectors are widely used in basic research and clinical applications for gene transfer and long-term expression; however, safety issues have not yet been completely resolved. In this study, we characterized hepatocarcinomas that developed in mice 1 year after in utero administration of a feline-derived lentiviral vector. Mapped viral integration sites differed among tumors and did not coincide with the regions of chromosomal aberrations. Furthermore, gene expression profiling revealed that no known cancer-associated genes were deregulated in the vicinity of viral integrations. Nevertheless, five of the six tumors exhibited highly significant upregulation of E2F target genes, of which a majority are associated with oncogenesis, DNA damage response, and chromosomal instability. We further show in vivo and in vitro that E2F activation occurs early on following transduction of both fetal mice and cultured human hepatocytes. On the basis of the similarities in E2F target gene expression patterns among tumors and the lack of evidence implicating insertional mutagenesis, we propose that transduction of fetal mice with a feline lentiviral vector induces E2F-mediated major cellular processes that drive hepatocytes toward uncontrolled proliferation culminating in tumorigenesis.

Specific genomic and transcriptomic aberrations in tumors induced by partial hepatectomy of a chronically inflamed murine liver

“…Comparison of the genome-scale gene expression profiles of these six post-PHx tumors with those of spontaneous tumors of the 16-month-old Mdr2-KO mice which were analyzed previously [ 4 ] revealed surprisingly few common down-regulated (Figure 4A ) and up-regulated (Figure 4B ) genes in both tested datasets. We compared both datasets also for enrichment in four cancer-associated gene expression signatures: up-regulation of HCC-specific oncogenes, or chromosomal instability (CIN) genes, or E2F1 targets, and down-regulation of HCC-specific tumor suppressors (Table 1 ) [ 6 , 7 ]. At least 50% of post-PHx tumors were significantly enriched in Oncogenic, CIN, and E2F1 gene expression signatures, while in spontaneous tumors only solitary tumors were significantly enriched in either Oncogenic or E2F1 signature.…”

“… a Fold change thresholds in tumors vs. matched non-tumorous tissue. Gene lists for analysis of expression signatures of oncogenes, tumor suppressors and E2F1 targets have been described by us previously [ 7 ]; the 25-gene CIN signature – as described in [ 6 ]. Statistical significance (p value) of each gene signature was determined by Fisher test using R-software.…”

Healing of massive segmental femoral bone defects in minipigs by allogenic ASCs engineered with FLPo/Frt-based baculovirus vectors

“…However, both gammaretrovirus [44] and lentivirus [45,46] integrate the transgene into the chromosome and may induce insertional transformation. AAV may also integrate the transgene into the host chromosome [47] and elicit heptocellular carcinoma in mice [48].…”

Cartilage Tissue Engineering: Recent Advances and Perspectives from Gene Regulation/Therapy

“…Lentivirus belongs to the retrovirus family and is capable of transducing non‐dividing cells. However, lentiviral vectors also favor the integration into active transcription units and may induce insertional transformation and tumor formation . Therefore, the safe use of retroviral/lentiviral vectors in cartilage engineering requires further justification …”