RESUMO
Objective To investigate the roles and mechanisms of hepatocyte nuclear factor 4α (HNF4α) in chenodeoxycholic acid (CDCA) induced gastric intestinal metaplasia (IM).Methods After the immortalized gastric mucosal epithelial cells GES-1 were stimulated with CDCA at different concentration,the changes of HNF4α,caudal-related homeobox 2 (CDX2) and trefoil factor family 3 (TFF3) expressions at mRNA and protein levels in GES-1 cells and gastric cancer cell lines (AGS,SGC7901 and BGC823) were detected by real time-polymerase chain reaction (RT-PCR) and Western blotting.After GES-1 were transfected with HNF4α short hairpin RNA (shRNA) or control shRNA,and followed by CDCA stimulation,the expressions of HNF4α,CDX2 and TFF3 at protein level were determined by Western blotting.HNF4α was overexpressed in GES-1 cells and SGC7901 cells,and HNF4α was silenced in BGC823 cell line and AGS by lentiviral vector system.The expressions of HNF4α,CDX2 and TFF3 at mRNA and protein levels were tested by RT-PCR and Western blotting.Luciferase reporter assay was used to analyze the regulation role of HNF4α on CDX2.T test was performed for statistical analysis.Results The expressions of HNF4α in GES-1,SGC7901,BGC823 and AGS cells at mRNA level were 1.00 ± 0.12,263.01±10.23,848.01±18.13 and 3 049.86±91.75,respectively.The mRNAlevels of HNF4α in AGS,BGC823 and SGC7901 cells were all higher than that of GES-1 cells,and the differences were statistically significant (t=33.23,46.72 and 25.62,all P＜0.01).The expressions of HNF4α in GES-1,SGC7901,BGC823 and AGS at protein level were consistent with mRNA level.The expressions of CDX2 and TFF3 at protein level of HNF4α shRNA transfected group were lower than those of non-HNF4α shRNA transfected group.In GES-1 cells,the expressions of HNF4α,CDX2 and TFF3 of HNF4α overexpressed group at mRNA level were 16 281.839 ± 1 843.017,6.275 ± 0.137 and 17.310± 1.533,respectively;which were all higher than those of overexpressed control group (1.000 ± 0.048,1.000 ± 0.012 and 1.000±0.108,respectively),and the differences were statistically significant (t =8.83,38.29 and 10.61,all P＜0.01).In AGS cells,the expressions of HNF4α,CDX2 and TFF3 of HNF4α silenced group at mRNA level were 0.021 ± 0.001,0.088 ± 0.007 and 0.074 ± 0.002,respectively,which were lower than those of silenced control group (1.000 ± 0.108,1.000 ± 0.131 and 1.000 ± 0.122),and the differences were statistically significant (t=9.09,6.93 and 7.57,all P＜0.01).In GES-1 overexpressed cells and AGS silenced cells,the expressions of HNF4α,CDX2,TFF3 at protein level were consistent with mRNA level.In double reporter plasmid containing the CDX2 promoter CDX2 1 (-2 000～-1 bp) and CDX2-2 (-1 510～1 bp),after transfected with HNF4α shRNA,the activities were 0.387 ± 0.013 and 0.533 ± 0.040,respectively,which were lower than those of HNF4α shRNA transfected control group (0.605 ± 0.012 and 0.882 ± 0.019),and the differences were statistically significant (t =21.49 and 13.53,both P＜0.01).Conclusion HNF4α may be involved in bile acid induced intestinal metaplasia by upregulating the expression of CDX2.