Exogenous PTEN gene induces apoptosis in breast carcinoma cell line MDA468

Abstract

The effects and mechanisms of exogenous phosphatase and tensin homolog deleted from chromosome ten (PTEN) gene on phosphatase activity-dependent apoptosis of breast cancer cell line MDA468 were investigated. PTEN gene packaged with lipofectin was transferred into breast cancer cell line MDA468 and parental MDA468 cells served as controls. RT-PCR and Western blot were done to detect the expression of target genes. The expression of phosphospecific protein kinase B (PKB/Akt) and focal adhesion kinase (FAK) protein stimulated by epidermal growth factor (EGF) was also detected. Apoptosis was determined by flow cytometry with a double-staining method using FITC-conjugated annexin V and PI. MDA468 cells transfected with PTEN gene could express PTEN mRNA and protein. PTEN decreased the phosphorylation level of AKT protein and down-regulated FAK protein expression in MDA468 stimulated by EGF. The apoptosis rate was 21.68%. PTEN induced breast cancer apoptosis phosphatase activity-dependently. The mechanism is possibly related with phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB)/AKT signaling pathway. Those results may provide new clues on the gene therapy in breast cancer.

Keywords

breast cancer / PTEN / tumor suppressor / PI3K/Akt / FAK / apoptosis

References

[1] ChuE. C., TarnawskiA. S.. PTEN regulatory functions in tumor suppression and cell biology. Med Sci Monit, 2004, 10: 235-241

[2] MyersM. P., StolarovJ. P., EngC., et al.. P-TEN, the tumor suppressor from human chromosome 10q23, is a dual-specificity phosphatase. Proc Natl Acad Sci USA, 1997, 94: 9052-9057

[3] ChenQ. Y., ChenD. D.. Advances in multifunction PTEN gene and breast cancer. Guowai Yixue Waikexue Fence (Chinese), 2002, 29: 360-362

[4] DaviesM. A., LuY., SanoT., et al.. Adenoviral transgene expression of MMAC/PTEN in human glioma cells inhibits Akt activation and induces anoikis. Cancer Res, 1998, 58: 5285-5290

[5] MinaguchiT., MoriT., KanamoriY., et al.. Growth suppression of human ovarian cancer by adenovirus-mediated transfer of the PTEN gene. Cancer Res, 1999, 59: 6063-6067

[6] SambrookJ., RussellD. W.. HuangP. T.. Molecular Cloning: a laboratory manual, 20023rd ed.Beijing, Science Press: 32-34

[7] MaehamaT., DixonJ. E.. The tumor suppressor, PTEN/MMAC1 dephosphorylates the lipid second messenger, phosphatidylinositol 3,4,5-trisphosphate. J Biol Chem, 1998, 273: 13 375-13 378

[8] DeGraffenriedL. A., FulcherL., FriedrichsW. E., et al.. Reduced PTEN expression in breast cancer cells confers susceptibility to inhibitors of the PI3 kinase/Akt pathway. Ann Oncol, 2004, 15: 1510-1516

[9] CantleyL. C.. The phosphoinositide 3-Kinase pathway. Science, 2002, 296: 1655-1657

[10] TengD. H., HuR., LinH., et al.. MMAC1/PTEN mutations in primary tumor specimens and tumor cell lines. Cancer Res, 1997, 57: 5221-5225

[11] DepowskiP. L., RosenthalS. I., RossJ. S.. Loss of expression of the PTEN gene protein product is associated with poor outcome in breast cancer. Mod Pathol, 2001, 14: 672-676

[12] TsttsuiS., InoueH., YasudaK., et al.. Inactivation of PTEN is associated with a low p27kip1 protein expression in breast carcinoma. Cancer, 2005, 104: 2048-2053

[13] ChungJ. H., EngC.. Nuclear-cytoplasmic partitioning of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) differentially regulates the cell cycle and apoptosis. Cancer Res, 2005, 65: 8096-8100

[14] LuY., LinY. Z., LapushinR., et al.. The PTEN/ MMAC1/TEP tumor suppressor gene decreases cell growth and induces apoptosis and anoikis in breast cancer cells. Oncogene, 1999, 18: 7034-7045