title: Celastrol-induced apoptosis in human HaCaT keratinocytes involves the inhibition of NF-κB activity.
abstract: Psoriasis is a chronic inflammatory skin disease affecting 1-3% of the world's population. Traditional Chinese medicines have been extensively used for treating psoriasis with promising clinical results. Celastrol, a triterpenoid isolated from a Chinese herb Celastrus orbiculatus caulis, has been known to have diverse pharmacological effects such as anti-inflammatory, anti-cancer and antioxidant activities. The present study aimed at evaluating the anti-proliferative action of celastrol on cultured HaCaT cells and elucidating the mechanisms of action involved. Celastrol was shown to inhibit HaCaT cells growth with an IC₅₀ value of 1.1 μM as measured by MTT assay. The ability of celastrol to induce apoptosis was studied by flow cytometric and western blot analyses. Celastrol was found to be capable of inducing apoptosis in HaCaT cells as characterized by phosphatidyl-serine (PS) externalization, depolarization of mitochondrial membrane potential and activation of caspase-3. The apoptosis induced by celastrol could be suppressed by Z-IETD-FMK and Z-LEHD-FMK, the respective caspase-8 and caspase-9 inhibitor. In addition, western blot analysis revealed a significant augmentation in the protein expression of Bax and attenuation in Bcl-2, suggesting that the celastrol-induced apoptosis acts through both death receptor and mitochondrial pathways. Moreover, western blot analysis on the expression of Rel/NF-κB demonstrated that the celastrol-mediated apoptosis on HaCaT cells was associated with the inhibition of the NF-κB pathway. Taken together, the present project has for the first time identified celastrol as a naturally occurring compound with potent apoptogenic action on cultured human keratinocytes, rendering it a promising candidate for further development into an anti-psoriatic agent.
authors.affiliation: School of Chinese Medicine, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China. linzx@cuhk.edu.hk
authors.forename: Lin-Li
authors.initials: LL
authors.lastname: Zhou
authors.forename: Zhi-Xiu
authors.initials: ZX
authors.lastname: Lin
authors.forename: Kwok-Pui
authors.initials: KP
authors.lastname: Fung
authors.forename: Christopher H K
authors.initials: CH
authors.lastname: Cheng
authors.forename: Chun-Tao
authors.initials: CT
authors.lastname: Che
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
authors.forename: Shi-Hua
authors.initials: SH
authors.lastname: Wu
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zuo
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D020128:Inhibitory Concentration 50; D015603:Keratinocytes / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D053978:Pentacyclic Triterpenes; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology*
chemical_list: D017304:Annexin A5; D004365:Drugs, Chinese Herbal; D016328:NF-kappa B; D053978:Pentacyclic Triterpenes; D019253:Proto-Oncogene Proteins c-bcl-2; D014315:Triterpenes; D020169:Caspases; C050414:celastrol