PTEN及其突变体对胃癌细胞AKT磷酸化的影响

Effects of PTEN and its mutants on AKT phosphorylation in gastric cancer cells

目的研究第10号染色体缺失的磷酸酶及张力蛋白同源基因(phosphatase and tensinhomolog deleted on chromosome 10,PTEN)及其磷酸酶区域突变后对胃癌细胞AKT磷酸化的影响。方法分别转染野生型PTEN(wild-type PTEN,wt PTEN)质粒、脂质磷酸酶和蛋白磷酸酶活性均突变的PTEN-C124S质粒、仅脂质磷酸酶活性突变的PTEN-G129E质粒至AGS细胞和BGC-823细胞。血清饥饿过夜后予各组细胞加入胰岛素或者重组人表皮生长因子(recombinant human epidermal growth factor,rh EGF)刺激,最后Western blot法检测AKT磷酸化水平。结果胰岛素和rh EGF均能刺激细胞引起AKT磷酸化,过表达PTEN基因能抑制胰岛素或rh EGF刺激引起的AKT磷酸化(P<0.05),转入功能性突变体PTEN-C124S或PTEN-G129E对AKT磷酸化无抑制作用(P>0.05)。结论 PTEN在胃癌细胞中能抑制胰岛素或rh EGF刺激引起的AKT磷酸化,其磷酸酶结构域N端第124或129位氨基酸发生点突变后无抑制作用。

Objective To study the effects of PTEN and missense mutations in PTEN phosphotase domain on AKT phosphorylation in AGS and BGC-823cells.Methods The plasmids of wtPTEN,PTEN-C124S which PTEN mutant is in both lipid and protein phosphotase domain and PTEN-G129E which PTEN mutant is only in lipid phosphotase domain were respectively transfected into AGS and BGC823cells.The cells were stimulated with insulin or rhEGF after serum starvation overnight.The levels of AKT phosphorylation were detected by Western blot.Results Both insulin and rhEGF can activate AKT phosphorylation in gastric cancer cells.Overexpressed PTEN inhibitedAKT phosphorylation induced by insulin or rhEGF(P<0.05).PTEN mutants C124S or G129E could not inhibitAKT phosphorylation(P>0.05).Conclusions PTEN can inhibit AKT phosphorylation induced by insulin or rhEGF in gastric cancer cells.Missense mutations in the124th or129th amino acid of PTEN phosphotase domain do not exert inhibitive function.