Necroptosis/regulated necrosis is a caspase-independent, but receptor interacting protein kinase (RIPK)-dependent form of cell death. In previous studies, neoalbaconol (NA), a constituent extracted from Albatrellus confluens, was demonstrated to induce necroptosis in some cancer cell lines. The molecular mechanism of NA-induced necroptosis is described in this research study. We determined that NA-induced cell death is partly dependent on tumor necrosis factor a (TNF alpha) feed-forward signaling. More importantly, NA abolished the ubiquitination of RIPK1 by down-regulating E3 ubiquitin ligases, cellular inhibitors of apoptosis protein 1/2 (cIAP1/2) and TNF alpha receptor-associated factors (TRAFs). The suppression of RIPK1 ubiquitination induced the activation of the non-canonical nuclear factor-kappa B (NF-kappa B) pathway and stimulated the transcription of TNF alpha. Moreover, we also found that NA caused RIPK3-mediated reactive oxygen species (ROS) production and contribution to cell death. Taken together, these results suggested that two distinct mechanisms are involved in NA-induced necroptosis and include RIPK1/NF-kappa B-dependent expression of TNF alpha and RIPK3-dependent generation of ROS.
National Key Basic Research Program of China [2009CB522300, 2011CB504305]
; State Key Program of National Natural Science Foundation of China 
; Hunan Provincial Innovation Foundation for Postgraduate [CX2012B082]
1.Cent S Univ, Xiangya Sch Med, Canc Res Inst, Changsha, Hunan, Peoples R China 2.Cent S Univ, Chinese Minist Educ, Key Lab, Changsha, Hunan, Peoples R China 3.Cent S Univ, Chinese Minist Publ Hlth, Key Lab Carcinogenesis, Changsha, Hunan, Peoples R China 4.Chinese Acad Sci, Kunming Inst Bot, State Key Lab Phytochem & Plant Resources West Ch, Beijing 100864, Yunnan, Peoples R China 5.Univ Minnesota, Hormel Inst, Austin, MN 55912 USA 6.Zhongshan Hosp, Liver Surg Dept, Liver Canc Inst, Shanghai, Peoples R China