NANOG modulates stemness in human colorectal cancer

Abstract

NANOG is a stem cell transcription factor that is essential for embryonic development, reprogramming normal adult cells and malignant transformation and progression. The nearly identical retrogene NANOGP8 is expressed in multiple cancers, but generally not in normal tissues and its function is not well defined. Our postulate is that NANOGP8 directly modulates the stemness of individual human colorectal carcinoma (CRC) cells. Stemness was measured in vitro as the spherogenicity of single CRC cells in serum free medium and the size of the side population and in vivo as tumorigenicity and experimental metastatic potential in NOD/SCID mice. We found that 80% of clinical liver metastases express a NANOG with 75% of the positive metastases containing NANOGP8 transcripts. 3 to 62% of single cells within 6 CRC lines form spheroids in serum free medium in suspension. NANOGP8 is translated into protein. The relative expression of a NANOG gene increased 8–122 fold during spheroid formation, more than the increase in OCT4 or SOX2 transcripts with NANOGP8 the more prevalent family member. shRNA to NANOG not only inhibits spherogenicity but also reduces expression of OCT4 and SOX2, the size of the side population and tumor growth in vivo. Inhibition of NANOG gene expression is associated with inhibition of proliferation and decreased phosphorylation of G2-related cell cycle proteins. Overexpression of NANOGP8 rescues single cell spherogenicity when NANOG gene expression is inhibited and increases the side population in CRC. Thus, NANOGP8 can substitute for NANOG in directly promoting stemness in CRC.

The Tissue-Reconstructing Ability of Colon CSCs Is Enhanced by FK506 and Suppressed by GSK3 Inhibition

“…4). Several preceding studies have argued that some CSC properties, such as enhanced tumorigenicity, may be inducible (5)(6)(7). However, these reports did not show whether these cells have the ability to differentiate into specific types of cancer tissues.…”

Reduction of NANOG Mediates the Inhibitory Effect of Aspirin on Tumor Growth and Stemness in Colorectal Cancer

“…Previous studies have shown that NANOG plays key roles in maintenance of CSCs stemness [32]. We thus hypothesized that NANOG might play an important role in aspirin-induced CSCs stemness suppression.…”

“…We detected the expression level of several stemness factors, including c-Myc, OCT4, NANOG and SOX2 [32, 41-43] by western blotting. Aspirin suppressed the stemness factors expression with increasing dose (Fig.…”

“…NANOG was reported to play a critical role in CRC stemness maintenance. Consistently, gene depletion of NANOG in colorectal cancer cell lines attenuates spheres formation ability and hampered tumorigenicity [32]. Conversely, overexpression of NANOG in colorectal cancer cells resulted in an increase in clonogenic potential and tumor formation in xenograft models [33].…”

Hepatic differentiation of human embryonic stem cells in a 3D bioreactor environment

“…The over-expression of Nanog in hESC has been demonstrated to contribute to the maintenance of the undifferentiated state in the absence of feeders or conditioned media for a period of time 89 . Interestingly the expression of Nanog has also been found in several neoplasia 90,91 and was reported to improve proliferation and life span together with Oct-4 in human mesenchymal stem cells over-expressing these two transcription factors 92 .…”