Inhibition of NADPH Oxidases Activity by Diphenyleneiodonium Chloride as a Mechanism of Senescence Induction in Human Cancer Cells.

Katarzyna Piszczatowska,Dorota Przybylska,Ewa Sikora,Grażyna Mosieniak

doi:10.3390/antiox9121248

Abstract

NADPH oxidases (NOX) are commonly expressed ROS-producing enzymes that participate in the regulation of many signaling pathways, which influence cell metabolism, survival, and proliferation. Due to their high expression in several different types of cancer it was postulated that NOX promote tumor progression, growth, and survival. Thus, the inhibition of NOX activity was considered to have therapeutic potential. One of the possible outcomes of anticancer therapy, which has recently gained much interest, is cancer cell senescence. The induction of senescence leads to prolonged inhibition of proliferation and contributes to tumor growth restriction. The aim of our studies was to investigate the influence of low, non-toxic doses of diphenyleneiodonium chloride (DPI), a potent inhibitor of flavoenzymes including NADPH oxidases, on p53-proficient and p53-deficient HCT116 human colon cancer cells and MCF-7 breast cancer cells. We demonstrated that the temporal treatment of HCT116 and MCF-7 cancer cells (both p53 wild-type) with DPI caused induction of senescence, that was correlated with decreased level of ROS and upregulation of p53/p21 proteins. On the contrary, in the case of p53−/− HCT116 cells, apoptosis was shown to be the prevailing effect of DPI treatment. Thus, our studies provided a proof that inhibiting ROS production, and by this means influencing ROS sensitive pathways, remains an alternative strategy to facilitate so called therapy-induced senescence in cancers.

Highlights

The role of oxidative stress in cellular transformation was postulated many years ago leading to the so called “free radical theory of cancer”
The analysis revealed that diphenyleneiodonium chloride (DPI) applied in a low, nanomolar concentration significantly decrease HCT116 cells growth
The sensitivity of p53 proficient and p53 deficient cells was very similar and no statistically significant differences between p53+/+ and p53−/− cells were revealed at either concentration of DPI (Figure 1A)

Summary

Introduction

The role of oxidative stress in cellular transformation was postulated many years ago leading to the so called “free radical theory of cancer”. The seminal paper by Oberley and colleagues presented the idea that reactive oxygen species act as second messengers and stimulate cell proliferation but could activate a cascade of molecular events that could lead to cell immortality [1]. A considerable experimental support has accumulated proving that reactive oxygen species (ROS) participate in transformation and cancer development in many ways. Increased ROS production can lead to direct damage of biomolecules, such as nucleic acids, and result in genomic instability, which is associated with development of many pathologies including cancer. ROS can modulate redox-sensitive signaling pathways leading to their activation or inhibition. The modification of proteins and lipids by ROS might influence cell functioning and, in consequence, promote uncontrolled cell growth and cell transformation [2]

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Conclusion