title: Piperlongumine chemosensitizes tumor cells through interaction with cysteine 179 of IκBα kinase, leading to suppression of NF-κB-regulated gene products.
abstract: Recently, two different reports appeared in prominent journals suggesting a mechanism by which piperlongumine, a pyridine alkaloid, mediates anticancer effects. In the current report, we describe another novel mechanism by which this alkaloid mediates its anticancer effects. We found that piperlongumine blocked NF-κB activated by TNFα and various other cancer promoters. This downregulation was accompanied by inhibition of phosphorylation and degradation of IκBα. Further investigation revealed that this pyridine alkaloid directly interacts with IκBα kinase (IKK) and inhibits its activity. Inhibition of IKK occurred through interaction with its cysteine 179 as the mutation of this residue to alanine abolished the activity of piperlongumine. Inhibition in NF-κB activity downregulated the expression of proteins involved in cell survival (Bcl-2, Bcl-xL, c-IAP-1, c-IAP-2, survivin), proliferation (c-Myc, cyclin D1), inflammation (COX-2, IL6), and invasion (ICAM-1, -9, CXCR-4, VEGF). Overall, our results reveal a novel mechanism by which piperlongumine can exhibit antitumor activity through downmodulation of proinflammatory pathway.
authors.affiliation: Cytokine Research Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas. General Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
authors.forename: Jia Gang
authors.initials: JG
authors.lastname: Han
authors.affiliation: Cytokine Research Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas. University of Mississippi Medical Center, Jackson, Mississippi.
authors.forename: Subash C
authors.initials: SC
authors.lastname: Gupta
authors.affiliation: Cytokine Research Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Sahdeo
authors.initials: S
authors.lastname: Prasad
authors.affiliation: Cytokine Research Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas. aggarwal@mdanderson.org.
authors.forename: Bharat B
authors.initials: BB
authors.lastname: Aggarwal
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003545:Cysteine / Q000378:metabolism*; D004148:Dioxolanes / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D061986:MCF-7 Cells; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism; D010881:Piperidones
chemical_list: D003545:Cysteine; D004148:Dioxolanes; D051550:I-kappa B Kinase; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C498077:piperlongumine; D010881:Piperidones