Expression Of Akt In Gastric Adenocarcinoma And Effect On Survival Apoptosis In Human Gastric Adenocarcinoma Cell

Objective:To investigate the expression of Akt in gastric adenocarcinoma and effect on survival,apoptosis in human gastric adenocarcinoma cell,the role of Akt in the development of gastric adenocarcinoma and its possible mechanisms.Mehtods:The expressions of Akt,PTEN,Bcl-2 and Bax were evaluated immunohistochemically in 54 gastric adenocarcinomas and 20 normal control group using the tissue microarray method.Immunocytochemistry was employed to detected the expression of Akt in human gastric adenocarcinoma cell line AGS.Then AGS,maintained in RPMI 1640 supplemented with 2% FBS or 10%FBS was treated with 0.1,1,5,10 and 20μM Akt inhibitor,Akt/Protein kinase B signaling inhibitor-2, respectively for 24 h and 48 h to evaluate the survival rate of tumor cells by MTS assay method. 20μM API-2 were added to the cells cultured in RPMI 1640 containing 2% FBS for 24 h and 48 h to estimate the apoptosis index of cancer cells.Annexin V-FITC apoptosis detection kit I was used to determine the ratio of viable apoptotic tumor cells by flow cytometry. The same experimental procedures were also performed in the control cells that were treated with corresponding vehicles DMSO instead of API-2.Results:1 The expression levels of Akt in cancerous tissues were higher than those in normal control tissues . The Akt was found expressed in 74.1% gastric adenocarcinoma cancers,and the abundance of Akt was significantly associated with poorly differentiated phenotype(χ2=11.307,P<0.05).No significant difference was found between the expression levels of Akt and gastric adenocarcinoma clinicopathological parameters,such as age,sex,histological type,differentiation degree,depth of invasion,vascular invasion,lymph node metastasis and pathological stage(P>0.05).2 Expression of PTEN was positive in 63% (34/54) gastric adenocarcinoma patients and in 80%(16/20) normal control cases. There were no significant correlations between PTEN expression and the clinicopathological findings(P>0.05).3 Bcl-2 expression was observed in 53.7% of patients (29/54) diagnosed with gastric adenocarcinoma,significantly different from that of normal control tissues(χ2=8.908 and,P<0.05).No particular relationship was found with any clinicopathological factor(P>0.05).4 The rate of Bax expression of patients with and without gastric adenocarcinoma were 61.1% and 30%,respectively. There was no significant differrence in positive rate between the two groups.Expression of Bax showed no significant correlations with clinicopathological variables(P>0.05).5 PTEN and Bax were not correlated with the immunohistochemical expression of AKT(P>0.05),while there was positive correlation between Bcl-2 and Akt immunoreactivity(r=0.298,P<0.05).6 There was Akt expression in human gastric adenocarcinoma cell line AGS.7 After exposed to API-2 at the concentrations of more than 1μM,AGS cells, cultured in RPMI1640 containing 2% FBS or 10% FBS,exhibited a dose- depen- dent inhibition of growth,The survival of AGS cells was significantly reduced when the cells were exposed to 1,5,10 and 20μM of API-2 for 24 and 48 h compared with that of their control counterparts (F=6.078 or F=5.043,P<0.05), exhibited in a time-dependent manner,and the survival rate to be as low as 37.06% or 47.94% when 20μM of API-2 was applied for 48h.8 The concentrations of FBS,2% FBS or 10% FBS,have no significant different effect on the survival of AGS cells ,when combined with the doses and times to analysis.9 API-2 treatment with 20μM for 24h increases the number of viable apoptotic cells of AGS cells compared to those of DMSO treatment(P<0.05).Conclusions:1 Akt,Bcl-2 and Bax proteins expressions were higher in gastric adenocarcinoma than that of normal control group , may relate with the development of gastric adenocarcinoma;Akt was significantly associated with the abundance of Bcl-2.2 Akt expression was detected in AGS cells.Akt inhibitor,API-2,decreased survival and promoted apoptosis in AGS cells.Our study suggests that Akt may plays an important role in preventing apoptosis and increasing survival of gastric adenocarcinoma cells.