Epigenetic regulation of pluripotent genes mediates stem cell features in human hepatocellular carcinoma and cancer cell lines.

PLoS ONE. 2013;8(9):e72435 DOI 10.1371/journal.pone.0072435

 

Journal Homepage

Journal Title: PLoS ONE

ISSN: 1932-6203 (Online)

Publisher: Public Library of Science (PLoS)

LCC Subject Category: Medicine | Science

Country of publisher: United States

Language of fulltext: English

Full-text formats available: PDF, HTML, XML

 

AUTHORS


Xiao Qi Wang

Ray Kit Ng

Xiaoyan Ming

Wu Zhang

Lin Chen

Andrew C Y Chu

Roberta Pang

Chung Mau Lo

Sai Wah Tsao

Xuqing Liu

Ronnie T P Poon

Sheung Tat Fan

EDITORIAL INFORMATION

Peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 24 weeks

 

Abstract | Full Text

Activation of the stem cell transcriptional circuitry is an important event in cancer development. Although cancer cells demonstrate a stem cell-like gene expression signature, the epigenetic regulation of pluripotency-associated genes in cancers remains poorly understood. In this study, we characterized the epigenetic regulation of the pluripotency-associated genes NANOG, OCT4, c-MYC, KLF4, and SOX2 in a variety of cancer cell lines and in primary tumor samples, and investigated the re-activation of pluripotency regulatory circuits in cancer progression. Differential patterns of DNA methylation, histone modifications, and gene expression of pluripotent genes were demonstrated in different types of cancers, which may reflect their tissue origins. NANOG promoter hypomethylation and gene upregulation were found in metastatic human liver cancer cells and human hepatocellular carcinoma (HCC) primary tumor tissues. The upregulation of NANOG, together with p53 depletion, was significantly associated with clinical late stage of HCC. A pro-metastatic role of NANOG in colon cancer cells was also demonstrated, using a NANOG-overexpressing orthotopic tumor implantation mouse model. Demethylation of NANOG promoter was observed in CD133+(high) cancer cells. In accordance, overexpression of NANOG resulted in an increase in the population of CD133+(high) cells. In addition, we demonstrated a cross-regulation between OCT4 and NANOG in cancer cells via reprogramming of promoter methylation. Taken together, epigenetic reprogramming of NANOG can lead to the acquisition of stem cell-like properties. These results underscore the restoration of pluripotency circuits in cancer cells as a potential mechanism for cancer progression.