Pluripotency-associated genes in human nasopharyngeal carcinoma CNE-2 cells are reactivated by a unique epigenetic sub-microenvironment.
BACKGROUND
There is increasing evidence that cancers contain their own stem-like cells, and particular attention has been paid to one subset of cancer-stem cells termed side population (SP). Stem cells under normal physical conditions are tightly controlled by their microenvironment, however, the regulatory role of the microenvironment surrounding cancer stem cells is not well characterized yet. In this study we found that the phenotype of SP can be "generated" by macrophage-like cells under conditioned culture. Furthermore the gene regulation pathway involved in cellular reprogramming process was investigated.


METHODS
The selection and identification of SP in 50 CNE-2 single cell clones were performed by flow cytometry. The transwell assay and immunofluorescence staining were used to measure migration and cancer stem cell characters of non-SP single clone cells cultured with conditioned medium respectively. The subtraction suppression hybridization (SSH) technique and northern blotting analysis was applied to explore the pluripotency-associated genes under a unique epigenetic sub-microenvironment.


RESULTS
Among 50 clones, only one did not possess SP subpopulation while others did. The non-SP cells induced by macrophage-like cells showed more aggressive characters, which increased cell migration compared with the control cells and showed some fraction of SP phenotype. These cells expressed distinguished level of pluripotency-associated genes such as ADP-ribosylation factor-like 6 interacting protein (ARMER), poly (rC) binding protein 1 (PCBP1) and pyruvate dehydrogenase E1-beta subunit (PDHB) when subjected to the environment.


CONCLUSIONS
To our knowledge, this is the first study to demonstrate that non-SP single-clone cells can be induced to generate a SP phenotype when they are cultured with conditioned medium of macrophage-like cells, which is associated with the reactivation of pluripotency-associated genes.
Cao
Jun-Xia
JX
State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, 650 Dongfeng Road, Guangzhou 510060, PR China. jun-xia.cao@jax.org
Cui
Yu-Xin
YX
Long
Zi-Jie
ZJ
Dai
Zhong-Min
ZM
Lin
Ji-Yan
JY
Liang
Yi
Y
Zheng
Fei-Meng
FM
Zeng
Yi-Xin
YX
Liu
Quentin
Q
D002277:Carcinoma / Q000235:genetics* / Q000473:pathology*; D018929:Cell Culture Techniques / Q000379:methods; D045744:Cell Line, Tumor; D002465:Cell Movement; D002469:Cell Separation; D017077:Culture Media, Conditioned / Q000378:metabolism; D044127:Epigenesis, Genetic; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008264:Macrophages / Q000166:cytology; D008856:Microscopy, Fluorescence / Q000379:methods; D009303:Nasopharyngeal Neoplasms / Q000235:genetics* / Q000473:pathology*; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000166:cytology*; D009693:Nucleic Acid Hybridization
D017077:Culture Media, Conditioned