Nimbolide, a neem limonoid abrogates canonical NF-κB and Wnt signaling to induce caspase-dependent apoptosis in human hepatocarcinoma (HepG2) cells

Nuclear factor kappa B (NF-κB), an oncogenic signaling factor plays a critical role in the development and progression of various cancers. The objective of this study was to investigate the effect of nimbolide, a neem derived tetranortriterpenoid on NF-κB signaling and its downstream events - Wnt/β-catenin activation and apoptosis evasion in human hepatocarcinoma (HepG2) cells by evaluating NF-κB family members (NF-κB-p50, p65, IκB-α, p-IκB-α, and IKKβ), members of Wnt signaling (GSK-3β and β-catenin), and intrinsic apoptosis (Bcl-2, Bax, cytochrome c, Smac/DIABLO, caspase-3, and caspase-9). Our results demonstrate that nimbolide concurrently abrogates canonical NF-κB and Wnt signaling and induces intrinsic apoptosis in HepG2 cells. These data suggest that phytochemicals such as nimbolide that can target multiple steps along the NF-κB signaling circuit are promising candidates for future phytochemical-based mechanistic pathway targeted anticancer regimens. © 2012 Elsevier B.V. All rights reserved.