Expression Of CD97 And CD55 And Silencing Effect Of SiRNA-CD97 In Gastric Carcinoma Cell Lines

Part 1Expression of CD97 and CD55 and capacity of migration and invasion in gastric carcinoma cell linesObjective: to detect the expression of gene and protein of CD97 and CD55 in gastric carcinoma cell lines, to investigate the relation between the expression of CD97 and CD55 and the capacity of migration and invasion in gastric carcinoma cell lines.Methods: Gastric carcinoma cell lines: 23131, AGS, BGC823, KATO-III, MGC803 and SGC7901 were adopted. The expression of CD97 isoform mRNA and CD55 mRNA were detected by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of CD97 and CD55 protein were measured by fluorescence-activated cell sorting (FACS). The ability of migration and invasion were evaluated by transwell test.Results: All three CD97EGF isoform mRNA, CD97TM7 mRNA and CD55 mRNA were present in the cell lines, the expression of each mRNA varied between the cell lines. CD97EGF, CD97stalk and CD55 protein were present in the cell lines, the expression level of CD97EGF well correlated with that of CD97stalk (r= 1.000, P<0.001), there were no relationship between the expression level of CD55 andCD97EGF or CD97stalk (P>0.05). MGC803 cell line had the most migration and invasion cell number, KATO-III cell line had the least migration and invasion cell number, the migrated cell number had strong correlation with invasive cell number (r=0.943, P=0.005). There was a strong correlation between the expression level of CD97EGF as well as CD97stalk protein and migration as well as invasion capacity of cell lines (P<0.05), on the other hand, the expression level of CD55 had no relation to migration as well as invasion capacity of cell lines.Conclusion: There are varied expression level of gene and protein of CD97 and CD55 in gastric carcinoma cell lines. There is a strong correlation between the expression level of CD97EGF as well as CD97stalk protein and migration as well as invasion capacity of cell lines.Part 2Effect of CD97 gene silencing by small interfering RNA on migration and invasion of gastric carcinoma cell linesObjective: to investigate the effect of CD97 gene silencing by small interfering RNA on migration and invasion of gastric carcinoma cell lines.Methods: Gastric carcinoma cell lines: AGS and MGC803 were adopted. Four pairs of siRNA were designed according to the CD97 gene sequence and synthesized chemically. These siRNA were transfected into the AGS cells. Forty-eight hours after transfection, the cell total RNA was extracted, Real time PCR were used to detect the mRNA decrease so as to screen the most effective siRNA to be used in this experiment. Forty-eight hours after transfection, the cell total RNA was extracted forReal time PCR, Seventy-two hours after transfection, the expression change of CD97 protein were measured by fluoresceence-activated cell sorting (FACS) and the ability change of migration and invasion were evaluated by transwell test. The proliferation of cells were measured by MTT test.Results: Real time PCR and FACS revealed that cd97-siRNA notably down-regulated CD97 expression at both mRNA and protein levels. The mRNA level decreased (89.34±9.95)% and (95.42±1.93)% for AGS and MGC803 respectively. The CD97EGF and CD97stalk protein level of AGS decreased (19.29±3.45)% and (30.11±5.93)% respectively. The CD97EGF and CD97stalk protein level of MGC803 decreased (26.25±5.73)% and (16.22±3.23)% respectively. Cell proliferation did not change after siRNA transfection. The migration and invasion cell number of AGS were decreased (67.63± 12.03)% and (68.02± 15.63)% respectively. The migration and invasion cell number of MGC803 were decreased (14.92±2.03)% and (22.09±5.43)% respectively.Conclusion: siRNA can effectively inhibit CD97expression and restrain the migration and invasion capacity of gastric carcinoma cell lines, suggesting that CD97 play an important role in the metastasis of gastric cancer.