The Effects of Reactive Oxygen Species on PTEN Expression in HTB-11 and IMR-32 Neuroblastoma Cells

PTEN, or phosphatase and tensin, is a protein that plays a crucial role in cellular apoptosis, making it a vital tumor suppressor. Though PTEN has well known functions in various types of cancers, much remains unclear about its full role and mechanism. Studies have shown that, at high amounts of oxidative stress, PTEN is inactivated by either direct or indirect mechanisms. In order to determine the effects of low concentrations of the oxidants hydrogen peroxide and tert-butyl hydroperoxide, the neuroblastoma cell lines HTB-11 and IMR-32 were exposed to 10 μM of the respective oxidants at half hour time increments between 0 and 4 hours. Immunofluorescence imaging was conducted to show the expression of PTEN in cell samples of each time increment in order for the abundance and localization of PTEN in HTB-11 neuroblastoma cells to be quantitatively analyzed. The elevation of both PTEN abundance and localization with exposure to low concentrations of both reactive oxygen species was observed in HTB-11 neuroblatoma cells. This observation may be explained by the deactivation of various transmembrane protein receptors, affecting the normal phosphorylation cascade of the PI3K pathway. A subsequent decrease in both PTEN abundance and localization towards the later range of reactive oxygen species exposure may indicate the initiation of apoptosis. The possibility of such a conclusion was validated but not conclusively proven by cell viability tests conducted in this study