title: Isoalantolactone inhibits constitutive NF-κB activation and induces reactive oxygen species-mediated apoptosis in osteosarcoma U2OS cells through mitochondrial dysfunction.
abstract: Human osteosarcoma is an aggressive tumor which frequently resists chemotherapy; therefore, the search for new agents for its treatment is of great importance. Isoalantolactone, isolated from Inula spp., has been reported to inhibit the growth of several types of cancer cells. However, no prior research has been conducted to demonstrate the antiproliferative potential of isoalantolactone on osteosarcoma. The present study is the first to investigate the effects of isoalantolactone on cell viability in human osteosarcoma U2OS, MG-63 and Saos-2 cells, and its mechanism of action in U2OS cells. Our results demonstrated that isoalantolactone triggered S and mainly G2/M cell cycle phase arrest, accompanied by the downregulation of the expression of cyclin B1 at the protein and mRNA levels. Moreover, isoalantolactone induced apoptosis that was associated with reactive oxygen species (ROS) generation and the dissipation of mitochondrial membrane potential (MMP). Furthermore, our results indicated that this compound upregulated DR5, FADD and cleaved caspase-8, increased the interation between DR5 and FADD, and inhibited the expression of nuclear NF-κBp65. We also found that isoalantolactone-induced apoptosis was associated with the downregulation of Bcl-2 and upregulation of Bax, which finally led to the activation of caspase-3 and its downstream substrate, PARP, in osteosarcoma U2OS cells. Isoalantolactone-induced apoptosis was markedly abrogated when the cells were pretreated with N-acetylcysteine (NAC), a specific ROS inhibitor, suggesting that the apoptosis-inducing effect of isoalantolactone in osteosarcoma cells was mediated by reactive oxygen species. Taken together, our data demonstrated that isoalantolactone induces ROS-dependent apoptosis in U2OS cells via a novel mechanism involving inhibition of NF-κBp65 and provide the rationale for further in vivo and preclinical investigation of isoalantolactone against osteosarcoma.
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Di
authors.affiliation: College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, P.R. China.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Khan
authors.affiliation: Department of Biological Sciences, University of Sargodha Sub-Campus Bhakkar, Punjab, Pakistan.
authors.forename: Azhar
authors.initials: A
authors.lastname: Rasul
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Meiyan
authors.initials: M
authors.lastname: Sun
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Sui
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Lili
authors.initials: L
authors.lastname: Zhong
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Longfei
authors.initials: L
authors.lastname: Yang
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Pain Treatment, Binzhou Medical College Affiliated Hospital, Binzhou, Shandong, P.R. China.
authors.forename: Liangtao
authors.initials: L
authors.lastname: Feng
authors.affiliation: Central Research Laboratory, Jilin University Bethune Second Hospital, Changchun, Jilin, P.R. China.
authors.forename: Tonghui
authors.initials: T
authors.lastname: Ma
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001859:Bone Neoplasms; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000187:drug effects* / Q000378:metabolism; D012516:Osteosarcoma; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes / Q000494:pharmacology*
chemical_list: D016328:NF-kappa B; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; C032787:isoalantolactone