Withaferin A disrupts ubiquitin-based NEMO reorganization induced by canonical NF-κB signaling

Abstract

The NF-κB family of transcription factors regulates numerous cellular processes, including cell proliferation and survival responses. The constitutive activation of NF-κB has also emerged as an important oncogenic driver in many malignancies, such as activated B-cell like diffuse large B cell lymphoma, among others. In this study, we investigated the impact and mechanisms of action of Withaferin A, a naturally produced steroidal lactone, against both signal-inducible as well as constitutive NF-κB activities. We found that Withaferin A is a robust inhibitor of canonical and constitutive NF-κB activities, leading to apoptosis of certain lymphoma lines. In the canonical pathway induced by TNF, Withaferin A did not disrupt RIP1 polyubiquitination or NEMO-IKKβ interaction and was a poor direct IKKβ inhibitor, but prevented the formation of TNF induced NEMO foci which colocalized with TNF ligand. While GFP-NEMO efficiently formed TNF-induced foci, a GFP-NEMOY308S mutant that is defective in binding to polyubiquitin chains did not form foci. Our study reveals that Withaferin A is a novel type of IKK inhibitor which acts by disrupting NEMO reorganization into ubiquitin-based signaling structures in vivo.

Anti-cancer activity of withaferin A in B-cell lymphoma

“…36 Conversely, it has been suggested in lymphoma cells that WA inhibits TNF-a induced ubiquitin dependent organization of the IKKg (NEMO) rather than targeting IKKb directly. 37 Although we cannot rule out the direct effects of WA on IKKb, our data is consistent with the inhibitory effect of WA on Hsp90 chaperone activity which can also lead to down regulation of total IKKa/b levels (Fig. 4C) resulting in reduced translocation of p65 as shown by our fluorescence imaging studies (Fig.…”

Targeting Cdc20 as a novel cancer therapeutic strategy

“…Li et al reported that withaferin A enhanced oxaliplatin-induced growth suppression and apoptosis via reactive oxygen species-mediated inactivation of the PI3K/Akt pathway in pancreatic cancer cells (Li et al, 2015). Moreover, withaferin A was found to inhibit canonical and constitutive NF-κB activities, resulting in induction of cellular apoptosis in lymphoma lines (Jackson et al, 2014). Strikingly, withaferin A eliminates cancer stem cells in ovarian cancer cells, leading to reduction in tumor growth and inhibition of metastasis in an ovarian orthotopic mouse model (Kakar et al, 2014).…”

Nemo like kinase negatively regulates NF-κB activation and coelomocytes apoptosis in Apostichopus japonicus

“…The activated NLK also regulates several transcription factors, including Tcf4/Lef1, Notch (Ishitani et al, 1999(Ishitani et al, , 2010, Mad (Zeng et al, 2007), nerve growth factors (Ishitani et al, 2009), and NF-kB (Jackson et al, 2015); as such, this protein exhibits various roles in signal regulation. Meanwhile, the NLK protein down-regulates caspase-3 expression in traumatic brain injury and is associated with neuronal apoptosis (Li et al, 2012).…”