Reactive Oxygen Species P38 Research Articles

Synergistic Effect of ROS and p38 MAPK in Apoptosis of TM4 Cells Induced by Titanium Dioxide Nanoparticles.

The adverse effects of titanium dioxide nanoparticles (TiO2 NPs) on the integrity of the blood-testis barrier (BTB) are widely recognized. However, the underlying mechanisms remain incompletely understood. The integrity of the BTB is imperative for the preservation of male reproductive health. TM4 cells, which are major component of the BTB, play a critical role in its integrity. The apoptosis of TM4 cells is closely associated with the disruption of the BTB. Therefore, we selected TM4 cells as experimental models to investigate the apoptosis induced by TiO2 NPs and the underlying mechanisms. Cell viability, excessive production of reactive oxygen species (ROS), activation of p38 mitogen-activated protein kinase (MAPK) pathway, and apoptosis-related protein expression levels were determined under various concentrations (50, 100, 150, and 200 μg/mL) of TiO2 NPs exposure. The results indicate that TiO2 NPs induced the overproduction of ROS and activated the p38 MAPK signaling pathway, which subsequently led to apoptosis. The ROS scavenger N-acetylcysteine (NAC) was able to suppress the activation of p38 MAPK pathway induced by TiO2 NPs, while the p38 MAPK inhibitor SB203580 mitigated TiO2 NPs-induced ROS overproduction and subsequent apoptosis, suggesting an interplay between ROS overproduction and p38 MAPK pathway activation. In summary, TiO2 NPs induced mitochondrial apoptosis via the ROS-p38 MAPK axis. A positive feedback regulatory mechanism exists between the two processes, promoting apoptosis in TM4 cells through a synergistic effect.

Premature senescence in human breast cancer and colon cancer cells by tamoxifen-mediated reactive oxygen species generation

Premature senescence in human breast cancer and colon cancer cells by tamoxifen-mediated reactive oxygen species generation

Gallium compound GaQ3‐induced Ca2+ signalling triggers p53‐dependent and ‐independent apoptosis in cancer cells

BACKGROUND AND PURPOSE A novel anti-neoplastic gallium complex GaQ(3) (KP46), earlier developed by us, is currently in phase I clinical trial. GaQ(3) induced S-phase arrest and apoptosis via caspase/PARP cleavage in a variety of cancers. However, the underlying mechanism of apoptosis is unknown. Here, we have explored the mechanism(s) of GaQ(3) -induced apoptosis in cancer cells, focusing on p53 and intracellular Ca(2+) signalling. EXPERIMENTAL APPROACH GaQ(3) -induced cytotoxicity and apoptosis were determined in cancer cell lines, with different p53 status (p53(+/+) , p53(-/-) and p53 mutant). Time course analysis of intracellular Ca(2+) calcium release, p53 promoter activation, p53-nuclear/cytoplasmic movements and reactive oxygen species (ROS) were conducted. Ca(2+) -dependent formation of the p53-p300 transcriptional complex was analysed by co-immunoprecipitation and chromatin immunoprecipitation. Ca(2+) signalling, p53, p300 and ROS were serially knocked down to study Ca(2+) -p53-ROS ineractions in GaQ(3) -induced apoptosis. KEY RESULTS GaQ(3) triggered intracellular Ca(2+) release stabilizing p53-p300 complex and recruited p53 to p53 promoter, leading to p53 mRNA and protein synthesis. p53 induced higher intracellular Ca(2+) release and ROS followed by activation of p53 downstream genes including those for the micro RNA mir34a. In p53(-/-) and p53 mutant cells, GaQ(3) -induced Ca(2+) -signalling generated ROS. ROS further increased membrane translocation of FAS and FAS-mediated extrinsic apoptosis. CONCLUSIONS AND IMPLICATIONS This study disclosed a novel mechanism of Ca(2+) -signalling-mediated p53 activation and ROS up-regulation. Understanding the mechanism of GaQ(3) -induced apoptosis will help establish this gallium-based organic compound as a potent anti-cancer drug.