Title: Cadmium exposure activates Akt/ERK Signaling and pro-inflammatory COX-2 expression in human gallbladder epithelial cells via a ROS dependent mechanism.
Authors: Sharma, Priyanka; Caldwell, Trevar S; Rivera, Megan N; Gullapalli, Rama R
Published In Toxicol In Vitro, (2020 Sep)
Abstract: Gallbladder cancer (GBC) is the commonest biliary tract cancer with an ill-defined etiology. We examined the role of Cd+2 exposures in a primary human gallbladder (GB) cell line model in this study. Cd+2 exposures induced decreased cell viability, reactive oxygen species (ROS) generation, altered Akt/ERK signaling pathway activation, PGE2 and COX-2 expression in a human primary gallbladder epithelial cell model. Pharmacological inhibitors were used to determine the key drivers of elevated COX-2 expression due to Cd+2 exposure. Our results show Cd+2 causes a dose-dependent reduction in GB cell viability (EC50 value - 18.6 μM). Dose-dependent activation of phospho-Akt and phospho-ERK signaling pathways via increased phosphoprotein expression was observed due to Cd+2. Signaling activation of Akt and ERK was prevented by 5 mM N-Acetyl Cysteine (NAC), establishing the role of ROS as a key driver in the activation process. Importantly, we observed Cd+2 also caused a dose dependent change in the COX-2 and PGE2 expression levels. PI3K-Akt and NF-kB signaling pathways play a key role in Cd+2 exposure induced COX-2 activation in the gallbladder epithelial cells. In conclusion, our study measures the toxicological effects of Cd+2 exposures on human GB epithelial cells for the first time and establishes the role of Cd+2 as a possible driver of the Akt/ERK pathway overactivity and chronic inflammation in gallbladder carcinogenesis.
PubMed ID: 32512147
MeSH Terms: Cadmium/toxicity*; Cell Line; Cell Survival/drug effects; Cyclooxygenase 2/metabolism*; Dinoprostone/metabolism; Epithelial Cells/drug effects*; Epithelial Cells/metabolism; Gallbladder/cytology*; Glutathione/metabolism; Humans; MAP Kinase Signaling System/drug effects*; NF-kappa B/metabolism; Phosphatidylinositol 3-Kinases/metabolism; Proto-Oncogene Proteins c-akt/metabolism*; Reactive Oxygen Species/metabolism*