PTEN基因诱导人胚肾293细胞凋亡和细胞周期停滞

为了研究抑癌基因PTEN过表达对HEK293细胞凋亡和细胞周期停滞的作用，以野生型PTEN和PTEN突变子(T910G)表达质粒分别转染无PTEN表达的人胚肾293细胞，采用细胞质梯度DNA方法检测细胞凋亡，以流式细胞仪分析细胞周期.发现PTEN过表达能够诱导人胚肾293细胞质中出现梯度DNA，293细胞发生凋亡,PTEN过表达改变细胞周期分布，G0/G1期细胞增加13%，S期细胞下降15%.PTEN突变子对细胞凋亡和G1细胞停滞的影响略弱于野生型PTEN.PTEN基因过表达明显下调血小板衍生生长因子(PDGF)诱导的蛋白激酶B(PKB)和p42,p44-促分裂原活化蛋白激酶(MAPK)磷酸化水平，PTEN突变子对p42,p44-MAPK磷酸化水平的调节作用略弱于野生型PTEN.PTEN通过抑制细胞增殖，诱导细胞凋亡而影响细胞生长.

The Expression of PTEN in HEK293 Cells Induces Apoptosis and Cell Cycle Arrest

It was to study whether overexpression of the tumor suppressor PTEN in HEK293 cells could lead to apoptosis and cell cycle arrest. The wild-type and mutant T910G of PTEN expression plasmids were constructed and transfected into PTEN-null HEK293 cells respectively. Apoptosis was evaluated by the appearance of cytosolic low molecular DNA ladder on the gel. Cell cycle was determined by flow-cytometric analysis. The Western blot analysis was performed to determine the phosphorylation levels of PKB/Akt and MAPK. The present data showed that the overexpression of PTEN in HEK293 cells could induce apoptosis and resulted in an increase in G1 cell population through inhibiting PKB/Akt and MAPK phosphrylation stimulated by PDGF. Mutant PTEN cause less apoptosis and G1 arrest than wild-type PTEN. MAPK dephosphorylation caused by mutant PTEN was not so significant as by wild-type PTEN. These data suggested that PTEN may exert its tumor-suppressive effects through both the inhibition of cell cycle progression and the induction of apoptosis.