[Impact of PTEN gene knockout in human breast carcinoma MCF-7 cells on activity of JNK pathway].

BACKGROUND & OBJECTIVE: PTEN plays a critical role in the development and progression of many cancers. PTEN may act directly or indirectly to integrate complex signal network system, to influence the downstream signal pathway and target molecules. This study was to investigate the impact of PTEN gene knockout in human breast carcinoma MCF-7 cells on the activity of JNK pathway.

METHODS

MCF-7 cells were transfected with PTEN antisense oligonucleotide, or treated with 10 micromol/L SP600125, or received both transfection and SP600125 treatment. The expression of PTEN protein was detected by confocal spectral microscopy. The early stage cell apoptosis and cell cycle were detected by flow cytometry (FCM). The proliferation of MCF-7 cells was determined by MTT assay. The phosphorylated JNK and downstream substrate ATF-2, C-Jun protein were assayed by Western blot.

RESULTS

The expression of PTEN protein in MCF-7 cells was effectively blocked by PTEN antisense oligonucleotide. Early apoptosis of MCF-7 cells was induced by SP600125 after knocking down PTEN, with an early apoptosis rate of (32.4+/-2.4)%; MCF-7 cells were arrested at G1 phase. The proliferation rate was significantly lower in combination group than in SP600125 group and antisense oligonucleotide group (P < 0.05). The phosphorylation levels of JNK, ATF-2 and C-Jun was down-regulated in combination group.

CONCLUSIONS

PTEN plays an important role in the activation of JNK pathway in MCF-7 cells. Loss of PTEN results in the activation of JNK pathway in MCF-7 cells, and improves sensitivity of MCF-7 cells to JNK inhibitor.