Tet Transgene Activation is Disrupted in Lipogenic Triple Negative Breast Cancer Cells

Abstract

An important challenge for mammalian cell engineering is the unexpected response of transgenes to native transcriptional regulation pathways. One transgene can show different levels of expression at different genomic sites, in different cell types, and under different growth conditions. Collisions between transcription and DNA replication, heterochromatin encroachment, and viral defense have been linked to transgene silencing. In this study we identify fatty acid metabolism as another mediator of transgene behavior. Adipocyte secretome-induced lipogenesis in epithelial breast cancer cells was accompanied by the loss of expression from a Tet-TA regulated pCMV-AmCyan fluorescent protein (CFP) transgene. Transcription profiling verified the activation of lipid droplet biosynthesis genes, and revealed repression of loci at every chromosome, consistent with the idea that lipogenesis affects the availability of substrates and cofactors for global chromatin remodeling. Pre-induction of pCMV prevented full transgene silencing during lipogenesis. Our results provide new insights into the influence of the lipogenic epigenetic state on transgene behavior.