title: Celastrol blocks interleukin-6 gene expression via downregulation of NF-κB in prostate carcinoma cells.
abstract: Interleukin-6 (IL-6), a multifunctional cytokine, contributes to proliferation or differentiation of prostate carcinoma cells in a highly cell type-specific manner. Celastrol (3-hydroxy-24-nor-2oxo-1(10),3,5,7-friedelatetrane-29-oic acid), also named as tripterine, is extracted from root of Chinese traditional herb Tripterygiumwilfordii Hook f with potent anti-inflammatory and anti-cancer activities. In this study, we evaluated the molecular mechanisms of celastrol on cell proliferation and IL-6 gene expression in prostate carcinoma cells. 3H-thymidine incorporation and flow cytometric analysis indicated that celastrol treatments arrested the cell cycle at the G0/G1 phase, thus attenuating cell proliferation in prostate carcinoma PC-3 cells; moreover, celastrol induced cell apoptosis at higher dosage. Knockdown of IL-6 attenuated the anti-proliferative effect of celastrol on PC-3 cells. Results from ELISA and 5'-deletion transient gene expression assays indicated that celastrol treatment decreased IL-6 secretion and gene expression, and this effect is dependent on the NF-κB response element within IL-6 promoter area since mutation of the NF-κB response element from AAATGTCCCATTTTCCC to AAATGTTACATTTTCCC by site-directed mutagenesis abolished the inhibition of celastrol on the IL-6 promoter activity. Celastrol also attenuated the activation of PMA and TNFα on the gene expression and secretion of IL-6 in PC-3 cells. Immunoblot assays revealed that celastrol treatment downregulated the expressions of IKKα, p50 and p65, supporting the 5'-deletion transient gene expression assay result that celastrol blocked IL-6 expression through the NF-κB pathway in PC-3 cells. For the first time, our results concluded that celastrol attenuates PC-3 cell proliferation via downregulation of IL-6 gene expression through the NF-κB-dependent pathway.
authors.affiliation: Department of General Surgery, Chang Gung Memorial Hospital, Keelung, Taiwan, ROC.
authors.forename: Kun-Chun
authors.initials: KC
authors.lastname: Chiang
authors.affiliation: Department of Urology, Chang Gung Memorial Hospital, Kwei-Shan, Tao-Yuan, Taiwan, ROC.
authors.forename: Ke-Hung
authors.initials: KH
authors.lastname: Tsui
authors.affiliation: Department of Anatomy, School of Medicine, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan, ROC.
authors.forename: Li-Chuan
authors.initials: LC
authors.lastname: Chung
authors.affiliation: Department of General Surgery, Chang Gung Memorial Hospital, Kwei-Shan, Tao-Yuan, Taiwan, ROC.
authors.forename: Chun-Nan
authors.initials: CN
authors.lastname: Yeh
authors.affiliation: National Kaohsiung University of Hospitality and Tourism, Hsiao-Kang, Kaohsiung Taiwan, ROC.
authors.forename: Wen-Tsung
authors.initials: WT
authors.lastname: Chen
authors.affiliation: Department of Urology, Chang Gung Memorial Hospital, Kwei-Shan, Tao-Yuan, Taiwan, ROC.
authors.forename: Phei-Lang
authors.initials: PL
authors.lastname: Chang
authors.affiliation: Department of Anatomy, School of Medicine, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan, ROC.
authors.forename: Horng-Heng
authors.initials: HH
authors.lastname: Juang
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D053978:Pentacyclic Triterpenes; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014315:Triterpenes / Q000494:pharmacology*
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6; D016328:NF-kappa B; D009363:Neoplasm Proteins; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; C050414:celastrol