A β-glucosidase extracted from walnut (Juglans regia L.) green husk induces human hepatoma cell apoptosis via ROS-mediated p53 and NF-κB pathway.

Walnut green husk is the outermost green peel of walnut, which contains multiple natural ingredients with a variety of biological activities. In this study, an anti-tumor protein called Juglans regia L. husk protein (JRLHP) was isolated. Mass spectrometry and enzymatic activity analysis revealed that JRLHP was a β-glucosidase. JRLHP inhibited human hepatoma cancer cell growth and promoted apoptosis. JRLHP caused the decline of mitochondrial membrane potential and Bcl-2. Moreover, cytochrome c and Bax were elevated, and caspase-9 and caspase-3 were activated. JRLHP treatment led to excess reactive oxygen species (ROS). This was accompanied by increased p53 protein levels and the suppression of NF-κB pathway. NAC treatment reversed the effects of JRLHP on p53 and NF-κB pathway. Consequently, NAC also reduced the impacts of JRLHP on cell apoptosis and proteins related to apoptosis. Taken together, above results indicated that JRLHP induced HCC cell apoptosis by ROS-mediated p53 and NF-κB pathway.