PEG-SOD attenuates the mitogenic ERK1/2 signaling cascade induced by cyclosporin A in the liver and kidney of albino mice.

The calcineurin inhibitor, cyclosporin A (CsA) is one of the most common immunosuppressive agents used in organ transplantation. However, its clinical use is often limited by several unwanted effects including nephrotoxicity and hepatotoxicity. By using immunohistochemical and ELISA techniques, it was found that CsA administration causes a rapid activation of a disintegrin and metalloproteases-17 (ADAM-17), epidermal growth factor receptor (EGFR) and subsequent ERK1/2 phosphorylation in the liver and kidney of albino mice. Furthermore, this study presents mechanistic relevance of this signaling cascade involving reactive oxygen species (ROS)-mediated ADAM-17/EGFR/ERK1/2 activation as indicated by a clear reduction in ADAM-17 and EGFR activities as well as ERK1/2 phosphorylation when the animals pretreated with Polyethylene glycol-superoxide dismutase (PEG-SOD) before CsA administration. Collectively, our findings demonstrate that CsA has the ability to activate ADAM-17-mediated EGFR/ERK1/2 phosphorylation in the liver and kidney of albino mice in ROS-dependent manner. Finally, these data may support the concept of using antioxidant therapy as a valuable approach for the prevention of CsA-induced nephrotoxicity and hepatotoxicity.

Cyclosporin A activates human hepatocellular carcinoma (HepG2 cells) proliferation: implication of EGFR-mediated ERK1/2 signaling pathway.

One of the most common causes of cancer mortality worldwide is hepatocellular carcinoma (HCC). Extracellular signal-regulated kinase (ERK1/2) pathway has been shown to play an important role in the development and progression of HCC. Here, we demonstrate that the immunosuppressive agent cyclosporin A (CsA) has the ability to increase the cellular growth in HCC (HepG2 cells) via activation of ERK1/2 signaling cascade. It was found that ERK1/2 phosphorylation induced by CsA was highly reduced in the presence of the reactive oxygen species (ROS) scavenger polyethylene glycol-superoxide dismutase (PEG-SOD). Furthermore, it was observed that inhibition of metalloproteinase activity using TAPI-2 prevents ERK1/2 activation by CsA. Moreover, a disintegrin and metalloproteinase domain 17 (ADAM-17) activity was found to be critical for ERK phosphorylation by CsA. In addition, CsA-induced ERK phosphorylation was highly reduced in the presence of either neutralizing anti-heparin-binding-epidermal growth factor (HB-EGF) antibody or UO126 (MEK inhibitor). By using the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478, it was found that EGFR is critical for ERK phosphorylation induced by CsA. Furthermore, CsA-induced cell proliferation was strongly reduced in the presence of either PEG-SOD or TAPI-2 or neutralizing anti-ADAM17 antibody or neutralizing anti-HB-EGF antibody or AG1478 or UO126. Collectively, these data demonstrate that CsA has the ability to activate ERK1/2 signaling cascade that could be translated into an increase in HepG2 cell proliferation. Furthermore, these data support the role of ROS, ADAM-17, and EGFR in ERK1/2 signaling activation and subsequent cell proliferation induced by CsA in HepG2 cells.

Stem cell intervention ameliorates epigallocatechin-3-gallate/lipopolysaccharide-induced hepatotoxicity in mice.

Stem cells are identified as a novel cell therapy for regenerative medicine because of their ability to differentiate into many functional cell types. We have shown earlier a new model of hepatotoxicity in mice by administering (1500 mg/kg) epigallocatechin-3-gallate (EGCG) intragastric (IG) for 5 days after a single intraperitoneal dose (6 mg/kg) of lipopolysaccharide (LPS). In this study, we aimed to study the effect of intrahepatic (IH) injection of mouse embryonic stem cells (MESCs) on the hepatotoxicity induced by EGCG/LPS in mice. Mice were administered EGCG/LPS and rested for 3 days. MESCs were obtained from American Type Culture Collection and cultured in vitro for 4 days. Stem cells were injected IH. Seven days later, a single dose of LPS (6 mg/kg) followed by daily doses of IG administration of EGCG were re-administered for 5 days. At the end of the experiment, blood samples were collected for analysis of biochemical parameters associated with liver. Results showed that the group of mice that were administered MESCs prior to EGCG/LPS showed lower levels of alanine amino transferase, alkaline phosphatase, and bilirubin, higher albumin/globulin ratio, and less remarkable histopathological lesions. Also, that group of mice showed less expression of oxidative stress biomarkers (oxidized low-density lipoprotein Ox.LDL and chemokine CXCL16), less expression of nuclear protein receptors (retinoic acid receptor and retinoid X receptor), and less expression of inflammatory biomarkers (tumor necrosis factor α and transforming growth factor ß1) compared with other groups of mice that were not given MESCs. In conclusion, MESCs can ameliorate EGCG/LPS-induced hepatotoxicity in mice.