抑癌基因PTEN在乳腺癌激素耐受细胞中的表达

Effect of PTEN on the cell growth and PI3K/AKT signal pathway in Tamoxifen-resistant breast cancer cell-line LCC2

目的探讨抑癌基因PTEN对乳腺癌Tamoxifen耐受细胞系LCC2细胞增殖和PI3K/AKT信号通路的作用。方法在乳腺癌Tamoxifen耐受细胞系LCC2中,建立PTEN蜕皮激素稳定诱导表达系统,5μmol/L松甾酮A诱导PTEN表达后,检测PTEN的表达对LCC2细胞周期和细胞凋亡的影响以及对磷酸化AKT蛋白水平的作用。结果PTEN不能诱导细胞发生凋亡,但可以使细胞停滞于G1期。对照组中G1期的细胞百分比为58.74%,S期为22.58%;诱导表达24h后G1期的细胞百分比为67.98%,S期为15.36%(P<0.05);诱导表达48h后G1期的细胞百分比为69.47%,S期为12.70%(P<0.05)。松甾酮A诱导PTEN表达24h和48h后,与对照组相比PTEN表达后活化的AKT表达减少,但是24h和48h间差异无统计学意义(P>0.05)。结论PTEN可能通过PI3K/AKT信号转导途径诱导细胞生长的抑制,使细胞停滞于G1期,但不能诱导细胞凋亡。

Objective To study the effect of tumor suppression gene PTEN on the cell growth and the PI3K/AKT signal pathway in tamoxifen-resistant breast cancer cell line with ecdysone inducible mammalian expression system. Methods Wild-type PTEN eDNA was cloned into the inducible expression vector pIND and the resulting construct with pVgRXR was cotransfected into tamoxifen-resistant breast cancer cell line LCC2. Single cell clone was generated by 600 mg/L zeocin and 750 mg/L C-418 selection. 5μmol/L Ponasterone A was used to induce expression of the PTEN gene from the inducible expression vector. The expression of phosphospecific AKT was detected by immunoblot and the cell cycle and cell apoptosis by FACS, respectively. Results After induction of ponasterone A for 24 h or 48 h, the PTEN expression in LCC2 caused cell cycle arrest at the Gl phase but not apoptosis and inhibited the expression of phosphospecific AKT. Conclusion PTEN may suppress cell growth though the inhibition of PI3K/AKT signal pathway and cause cell cycle arrest at the G1 phase but not apoptosis. These results may provide new clues on the therapy in tamoxifen-resistance breast cancer.