Effects of NANOG/deleted in breast cancer 1 pathway on biological behavior of gastric cancer cells / 中华消化杂志

ABSTRACT

Objective To investigate the effects of NANOG/deleted in breast cancer 1 (DBC1)pathway on biological behavior of gastric cancer cells.Methods From May 2014 to May 2015,25 patients who underwent gastric cancer resection were selected.The expression of NANOG and DBC1 was detected by real time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting in N-tera,SGC-7901,HGC-27,MKN-45,MGC803,NCI-N87,BGC823 cell lines,normal gastric epithelial cell line GES-1 and gastric cancer tissues.The proliferation,apoptosis and colony formation ability of MKN-45 cells in short hairpin (sh)NANOG-1,shNANOG-2,sh-control and shDBC1 groups were determined by MTT assay,flow cytometry and colony forming assay.The effects on the expression of the two genes in MKN-45 cells were verified by polymerase chain reaction (PCR) in shNANOG,sh-control,shDBC1 and shDBC1+NANOG groups and the effects of down regulation of DBC1 on cell biological behavior were further investigated.The differences in gene expression profile after interference which were screened by gene chips and bioinformatics were analyzed.The mechanism of NANOG regulating DBC1 was explored by Dual-luciferase assay.T test was used for two groups comparison while one-way analysis of variance was for multiple groups.Results NANOG and NANOG mRNA were highly expressed in N-tera cells,which were 1.02±0.08 and 0.95 ±0.03,respectively,and the expressions in SGC-7901,HGC-27,MKN-45 and NCI-N87 cell lines were 0.67±0.03 and 0.64±0.04,0.58±0.02 and 0.28±0.02,0.83±0.03 and 1.04 ± 0.05,and 0.61 ± 0.02 and 0.64 ± 0.08,respectively;no expression was detected in normal gastric epithelial cell line GES-1,and the expressions in MKN-45 cells were the highest in gastric cancer cells (F=21.51 and 85.53,both P＜0.01).The expression of DBC1 in HGC-27,MGC803,NCIN87,SGC-7901,BGC823 and MKN-45 cells were 0.37±0.02,0.33±0.02,0.42±0.01,0.58±0.04,0.33±0.05,and 0.87±0.02,respectively;while there was no expression of NANOG,NANOG mRNA and DBC1 in GES-1 cells.The expression of NANOG mRNA and DBC1 was detected in gastric cancer tissues of 24.0％ (6/25) patients.Compared with that of the sh control group,the apoptosis rates of MKN-45 cells in the shNANOG-1,shNANOG-2 groups were increased ((2.24±0.17)％ vs (6.03±0.24) ％ and (6.95 ± 0.38) ％),and the difference was statistically significant (F =81.18,P ＜ 0.01).Compared with that of the sh-eontrol group,the colony forming abilities of MKN-45 cells in the shNANOG-1 and shNANOG-2 groups were significantly decreased (172.03±6.35 vs 74.32±5.32 and 53.08±3.82),and the difference was statistically significant(F=171.61,P＜0.01).The results of PCR showed that compared with that of sh-eontrol group,the expression levels of NANOG mRNA and DBC1 mRNA in shNANOG group were lower (1.04±0.05 vs 0.54±0.03,1.08±0.08 vs 0.42±0.03),the level of DBC1 mRNA in shDBC1 group was lower (1.08±0.08 vs 0.50±0.04),and the differences were statistically significant (t=9.15,7.37 and 6.06,all P＜0.01).The expression level of NANOG mRNA in shDBC1 + NANOG group was higher (1.04 ± 0.05 vs 3.01 ± 0.08),while the expression level of DBC1 mRNA was lower (1.08 ± 0.08 vs 0.71 ± 0.06),and the difference was statistically significant (t=-20.22 and 3.74,both P＜0.05).The expression level of DBC1 mRNA in shDBC1±NANOG group was higher than that in shDBC1 group (0.71±0.06 vs 0.50±0.04),and the difference was statistically significant (t=4.00,P＜0.05).Bioinformatic analysis showed that DBC1 gene promoter region had the potential NANOG protein binding sites.Dual-luciferase assay indicated NANOG played the role in transcription activation in DBC1 promoter regions.Conclusion NANOG and DBC1 are highly expressed in various gastric cancer cell lines.NANOG may affect the proliferation,apoptosis and colony formation of MKN-45 cells by regulating the expression of DBC1.NANOG/DBC1 pathway may be a promising new target of gastric cancer treatment.