| Objective:In this study,the expression of casein kinase 2 interaction protein 1(CKIP-1)was detected in Correa cascade reaction,patients with intestinal type gastric carcinoma(GC)and cell lines;analyzed the correlation between CKIP-1 and caudal-related homeobox 1(CDX1)expression and apoptosis level;detected the changes of CDX1 expression and apoptosis level in CKIP-1 sh RNA and CKIP-1 overexpression SGC7901 cells;preliminary explore the possible role of CKIP-1 in the occurrence and development of the intestinal type of GC,and provide some useful experimental data for the pathogenesis of the intestinal type of GC.Methods: The expression of CKIP-1 in clinical patients with gastric mucosal group,Intestinal metaplasia(IM)group,dysplasia group and the intestinal type of GC group were detected using immunohistochemical(IHC)staining.The correlation between CKIP-1 expression and IM type and grade,dysplasia grade and the differentiation of the intestinal type of GC were evaluated using Spearman correlation analysis.The expression of CKIP-1 in human intestinal GC cell lines were tested by Western Blot(WB).The expression of CDX1 in clinical patients with Correa cascade and the intestinal type of GC tissues and cell lines were detected using IHC staining and WB,respectively,and the correlation between CDX1 and CKIP-1 expression were evaluated using Spearman correlation analysis.The cell model of CKIP-1 sh RNA and CKIP-1 overexpression SGC7901 cells were established,and the expression of CDX1 were detected by WB.The expression of CKIP-1 and apoptosis in the intestinal type of GC patients were detected using IHC staining and TUNEL assay,respectively,and the correlation between the two was analyzed.The level of apoptosis in the intestinal type of GC cell lines were measured using Flow cytometry,and its correlation with CKIP-1 expression was analyzed.The levels of apoptosis and the expression of related apoptotic proteins(Bcl-2,Bax,Cleaved-caspase-3 and Cleaved-caspase-9)in CKIP-1 sh RNA and CKIP-1 overexpression SGC7901 cells were detected using Flow cytometry and WB,respectively.Results:(1)Compared with the gastric mucosa group,the percentage of cases with high CKIP-1 expression in the IM group increased significantly(P < 0.01).Compared with the IM and dysplastic group,the percentage of cases with high CKIP-1 expression in the intestinal type of GC group both decreased(both P < 0.01).The percentage of cases with high CKIP-1 expression in the dysplastic group was slightly lower than that in the IM group,but this difference was not significant.(2)The expression of CKIP-1 was correlated with the differentiation of the intestinal type of GC cells(r =-0.463,P < 0.01),the lower the level of differentiation of cancer cells,the lower the expression of CKIP-1.The expression of CKIP-1 were not correlated with IM type and grade and dysplasia grade.(3)Compared with highly differentiated MKN28 cells,the expression level of CKIP-1 in moderately differentiated SGC7901 cells and poorly differentiated BGC823 and AGS cells decreased(all P < 0.05).Compared with moderately differentiated SGC7901 cells,the expression of CKIP-1 in poorly differentiated BGC823 and AGS cells decreased(both P < 0.01),that is,the lower the level of differentiation of the intestinal type of GC cell lines,the lower the expression of CKIP-1.(4)Compared with the gastric mucosa group,the percentage of cases with high CDX1 expression in the IM group increased significantly(P < 0.01).Compared with the IM and dysplastic group,the percentage of cases with high CDX1 expression in the intestinal type of GC group both decreased(P < 0.01,P < 0.05).The percentage of cases with high CDX1 expression in the dysplastic group was slightly lower than that in the IM group,but this difference was not significant.Correlation analysis showed that the expressions of CKIP-1 and CDX1 were positively correlated in the IM group,dysplastic group and the intestinal type of GC group(r = 0.771,P < 0.01;r = 0.597,P < 0.01;r = 0.600,P < 0.01).(5)The expression of CDX1 decreased with the decrease of the differentiation degree of the intestinal type of GC cell lines.Correlation analysis showed that the expressions of CKIP-1 and CDX1 were positively correlated in differently differentiated intestinal type GC cell lines(r = 0.811,P < 0.01).(6)Compared with the blank control group,CDX1 expression of CKIP-1 sh RNA SGC7901 cells were decreased(P < 0.05),while CDX1 expression of CKIP-1 overexpression SGC7901 cells were increased(P < 0.05).(7)Compared with the gastric mucosa group,CKIP-1 expression in the IM group was significantly increased(P < 0.01).Compared with the IM group,CKIP-1 expression in the intestinal type of GC group was decreased(P < 0.01).(8)The lower the level of differentiation of the intestinal type GC patient cells,the lower the quantity of apoptotic cells and apoptotic index(P < 0.01).Spearman correlation analysis showed that the apoptosis index in the intestinal type GC patients was positively correlated with CKIP-1 expression(r = 0.761,P < 0.05).(9)Compared with the control group,the apoptosis rate in the CKIP-1 sh RNA SGC7901 cell group was significantly decreased(P < 0.01),the expression of Bcl-2 increased(P < 0.01),and the expression of Bax,Cleaved caspase-3 and Cleaved caspase-9 decreased(all P < 0.05).Compared with the control group,the apoptosis rate in the CKIP-1 overexpression SGC7901 cell group was significantly increased(P < 0.05),the expression of Bcl-2 was decreased(P < 0.01),and the expression of Bax,Cleaved caspase-3 and Cleaved caspase-9 increased(all P < 0.01).Conclusions:(1)In the Correa cascade reaction from IM,dysplasia to the intestinal type of GC,the expression of CKIP-1 gradually decreased,indicating that CKIP-1 can regulate the progression of IM to the intestinal type of GC as a tumor suppressor gene.CKIP-1 can down-regulate the expression of CDX1,which may be one of the reasons CKIP-1 is involved in the transform from IM to intestinal type GC.(2)CKIP-1 can promote the apoptosis of the intestinal type GC SGC7901 cells,and plays the role of tumor suppressor genes in the genesis and development of the intestinal type of GC,which may be achieved by down-regulating the expression of Bcl-2 and up-regulating the expression of Bax,Cleaved caspase-3 and Cleaved caspase-9. |
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