Embryonic NANOG activity defines colorectal cancer stem cells and modulates through AP1- and TCF-dependent mechanisms

Abstract

Embryonic NANOG (NANOG1) is considered as an important regulator of pluripotency while NANOGP8 (NANOG-pseudogene) plays a role in tumorigenesis. Herein, we show NANOG is expressed from both NANOG1 and NANOGP8 in human colorectal cancers (CRC). Enforced NANOG1-expression increases clonogenic potential and tumor formation in xenograft models, although it is expressed only in a small subpopulation of tumor cells and is colocalized with endogenous nuclear β-catenin(High) . Moreover, single NANOG1-CRCs form spherical aggregates, similar to the embryoid body of embryonic stem cells (ESCs), and express higher levels of stem-like Wnt-associated target genes. Furthermore, we show that NANOG1-expression is positively regulated by c-JUN and β-catenin/TCF4. Ectopic expression of c-Jun in murine Apc(Min/+) -ESCs results in the development of larger xenograft tumors with higher cell density compared to controls. Chromatin immunoprecipitation assays demonstrate that c-JUN binds to the NANOG1-promoter via the octamer M1 DNA element. Collectively, our data suggest that β-Catenin/TCF4 and c-JUN together drive a subpopulation of CRC tumor cells that adopt a stem-like phenotype via the NANOG1-promoter.