[Effects of enhancer of zeste homolog (EZH2) downregulation on the proliferation and invasion of nasopharyngeal carcinoma cell and the possible mechanisms].
OBJECTIVE
To investigate the effects of the enhancer of zeste homolog 2 (EZH2) gene on cell growth and invasion of the nasopharyngeal carcinoma (NPC).


METHODS
Recombinant lentivirus vector for shRNA delivery of EZH2 was constructed and transfected into 293FT cells. After collecting the viral particles, the NPC cell line 5-8F cells were transfected. The effects of EZH2 silence on cell proliferation and cell cycle were detected using MTT assay, plate colony formation assay and flow cytometry. The migration and invasion of 5-8F cells were determined by wound healing assay and matrigel invasion assay, respectively. The expressions of EZH2 and epithelial-mesenchymal transition (EMT)-related markers at mRNA and protein levels were examined by real-time PCR and Western blot respectively.


RESULTS
The expressions of EZH2 mRNA and protein in the transfected 5-8F cells were obviously reduced. MTT assay showed that EZH2 downregulation significantly inhibited the growth of 5-8F/shEZH2 cells (P < 0.001). Colony formation rate (84.44%) of 5-8F/shEZH2 cells was lower than control (31.56%, P = 0.001). Cell cycle analysis showed that most 5-8F/shEZH2 cells were arrested in G0/G1 phase, with a very low ratio of cells in S phase. Wound healing assay indicated that the migration ability of cells silencing EZH2 decreased significantly, and the 48-hour relative migration distance of 5-8F/ShEZH2 cells and control cells was 0.58 ± 0.05, and 0.81 ± 0.02, respectively (P < 0.000). Matrigel invasion assay, showed the invasive capacity of cells silencing EZH2 was significantly inhibited, with less penetrating cells (72.23 ± 4.08) compared to control (150.95 ± 16.27), P < 0.000. The mRNA expressions of epithelial markers E-cadherin and Keratin 18 in the cells silencing EZH2 increased by 177% and 158% respectively, and the mRNA expressions of mesenchymal markers β-catenin and N-cadherin decreased by 18.04% and 41.18% respectively. Similar results also were obtained with Western blot analysis.


CONCLUSIONS
EZH2 significantly enhanced the proliferation and invasion of nasopharyngeal carcinoma cells in vitro, which might be mediated by inducing EMT.
Department of Otorhinolaryngology Head and Neck Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
Bi-jun
BJ
LIANG
Xiang-ping
XP
LI
Juan
J
LU
Shao-xiong
SX
LIN
Xiong
X
LIU
Gang
G
LI
Bao
B
ZHANG
Lu
L
WANG
Hua-nan
HN
LUO
Ren-qiang
RQ
WAN
Wen-dong
WD
TIAN
D002277:Carcinoma; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D000071221:Enhancer of Zeste Homolog 2 Protein; D058750:Epithelial-Mesenchymal Transition; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000235:genetics* / Q000473:pathology*; D009361:Neoplasm Invasiveness; D063151:Polycomb Repressive Complex 2 / Q000235:genetics*
C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2