p110α and p110β isoforms of PI3K are involved in protection against H2O2 induced oxidative stress in cancer cells

Abstract

Purpose: Phosphatidylinositol-3 kinases (PI3Ks) are involved in regulating cell growth, proliferation, differentiation, apoptosis and survival. p110α and p110β, two ubiquitously expressed isoforms of PI3K signalling, are involved in growth factor mediated signaling and survival by generating second messengers. Earlier, we have generated GFP-fusion proteins of p110α and p110β and expressed them in normal and cancer cell-lines to investigate their subcellular localization and their role in various activities. Here, we sought to examine the role of p110α and p110β isoforms in protecting MCF-7 breast cancer cells against oxidative stress.

Material methods: We performed cytotoxicity assays, DNA transfection, Plasmid DNA preparation, western blotting, flourscence microscopy and statistical analysis.

Results: To know whether p110α and p110β are involved in protecting MCF-7 breast cancer cells against oxidative stress, we subjected MCF-7 cells to H2O2 treatment and observed a dose dependent decrease in cell viability and a marked increase in the levels of pro-apoptotic markers which include PARP, Bcl-2, Bax and procaspase-9. We then over-expressed recombinant GFP-fusion p110α and p110β proteins in MCF-7 cells and observed a significant decrease in apoptosis and a concomitant increase in pAkt levels.

Conclusion: We report the involvement of p110α and p110β isoforms of Class 1A PI3K signalling in rescue from oxidative stress-induced apoptosis in MCF-7 cells in Akt dependent manner.

Keywords: Akt; Apoptosis; Breast cancer; PI3K signalling.