title: Rosmarinic acid sensitizes cell death through suppression of TNF-alpha-induced NF-kappaB activation and ROS generation in human leukemia U937 cells.
abstract: Because tumor necrosis factor-alpha (TNF-alpha) is well-known to induce inflammatory responses, thus its clinical use is limited in cancer treatment. Rosmarinic acid (RA), a naturally occurring polyphenol flavonoid, has been reported to inhibit TNF-alpha-induced NF-kappaB activation in human dermal fibroblasts. However, the precise mechanisms of RA have not been well elucidated in TNF-alpha-mediated anti-cancer therapy. In this study, we found that RA treatment significantly sensitizes TNF-alpha-induced apoptosis in human leukemia U937 cells through the suppression of nuclear transcription factor-kappaB (NF-kappaB) and reactive oxygen species (ROS). Activation of caspases in response to TNF-alpha was markedly increased by RA treatment. However, pretreatment with the caspase-3 inhibitor, z-DEVD-fmk, was capable of significantly restoring cell viability in response to combined treatment. RA also suppressed NF-kappaB activation through inhibition of phosphorylation and degradation of IkappaBalpha, and nuclear translocation of p50 and p65. This inhibition was correlated with suppression of NF-kappaB-dependent anti-apoptotic proteins (IAP-1, IAP-2, and XIAP). RA treatment also normalized TNF-alpha-induced ROS generation. Additionally, ectopic Bcl-2 expressing U937 reversed combined treatment-induced cell death, cytochrome c release into cytosol, and collapse of mitochondrial potential. These results demonstrated that RA inhibits TNF-alpha-induced ROS generation and NF-kappaB activation, and enhances TNF-alpha-induced apoptosis.
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Republic of Korea.
authors.forename: Dong-Oh
authors.initials: DO
authors.lastname: Moon
authors.forename: Mun-Ock
authors.initials: MO
authors.lastname: Kim
authors.forename: Jae-Dong
authors.initials: JD
authors.lastname: Lee
authors.forename: Yung Hyun
authors.initials: YH
authors.lastname: Choi
authors.forename: Gi-Young
authors.initials: GY
authors.lastname: Kim
mesh_terms: D021581:Active Transport, Cell Nucleus; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002934:Cinnamates / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D053630:Depsides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D056945:Hep G2 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020298:U937 Cells; D000097123:Rosmarinic Acid
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D061945:Caspase Inhibitors; D020169:Caspases; D002934:Cinnamates; D015853:Cysteine Proteinase Inhibitors; D045304:Cytochromes c; D053630:Depsides; D020672:I-kappa B Proteins; D051034:Inhibitor of Apoptosis Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000097123:Rosmarinic Acid; C489548:NFKB1 protein, human; C000606204:NFKBIA protein, human; C498143:RELA protein, human