title: Targeted silencing of the oncogenic transcription factor SOX2 in breast cancer.
abstract: The transcription factor (TF) SOX2 is essential for the maintenance of pluripotency and self-renewal in embryonic stem cells. In addition to its normal stem cell function, SOX2 over-expression is associated with cancer development. The ability to selectively target this and other oncogenic TFs in cells, however, remains a significant challenge due to the 'undruggable' characteristics of these molecules. Here, we employ a zinc finger (ZF)-based artificial TF (ATF) approach to selectively suppress SOX2 gene expression in cancer cells. We engineered four different proteins each composed of 6ZF arrays designed to bind 18 bp sites in the SOX2 promoter and enhancer region, which controls SOX2 methylation. The 6ZF domains were linked to the Kruppel Associated Box (SKD) repressor domain. Three engineered proteins were able to bind their endogenous target sites and effectively suppress SOX2 expression (up to 95% repression efficiencies) in breast cancer cells. Targeted down-regulation of SOX2 expression resulted in decreased tumor cell proliferation and colony formation in these cells. Furthermore, induced expression of an ATF in a mouse model inhibited breast cancer cell growth. Collectively, these findings demonstrate the effectiveness and therapeutic potential of engineered ATFs to mediate potent and long-lasting down-regulation of oncogenic TF expression in cancer cells.
authors.affiliation: Epigenetic Editing, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
authors.forename: Sabine
authors.initials: S
authors.lastname: Stolzenburg
authors.forename: Marianne G
authors.initials: MG
authors.lastname: Rots
authors.forename: Adriana S
authors.initials: AS
authors.lastname: Beltran
authors.forename: Ashley G
authors.initials: AG
authors.lastname: Rivenbark
authors.forename: Xinni
authors.initials: X
authors.lastname: Yuan
authors.forename: Haili
authors.initials: H
authors.lastname: Qian
authors.forename: Brian D
authors.initials: BD
authors.lastname: Strahl
authors.forename: Pilar
authors.initials: P
authors.lastname: Blancafort
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004247:DNA / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D015202:Protein Engineering; D055748:SOXB1 Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors; D004247:DNA