Butein sensitizes human hepatoma cells to TRAIL-induced apoptosis via extracellular signal-regulated kinase/Sp1-dependent DR5 upregulation and NF-kappaB inactivation.
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces cell death in various types of cancer cells but has little or no effect on normal cells. Human hepatoma cells are resistant to TRAIL-induced apoptosis. Although butein is known to mediate anticancer, anti-inflammatory, and antioxidant activities, little is known about the mechanism of butein in terms of TRAIL-induced apoptosis of human hepatoma cells. In this study, we determined that butein enhances TRAIL-induced apoptosis in hepatoma cells through upregulation of DR5. Luciferase analysis showed that a 5'-flanking region containing four Sp1-binding sites within the DR5 promoter was enhanced by butein (-305/-300). Electrophoretic mobility shift assays and chromatin immunoprecipitation studies were used to analyze the elevation of Sp1 binding to DR5 promoter sites by butein. Point mutations of the Sp1-binding site also attenuated promoter activity. Furthermore, pretreatment of the blocking chimeric antibody and small interfering RNA for DR5 significantly suppressed TRAIL-mediated apoptosis by butein in Hep3B cells. Butein also stimulated extracellular signal-regulated kinase (ERK) activation, and the ERK inhibitor PD98059 blocked butein-induced DR5 expression and suppressed binding of Sp1 to the DR5 promoter. Additionally, generation of reactive oxygen species had no effect on cell viability, although pretreatment with N-acetyl-l-cysteine or glutathione inhibited combined treatment-induced reactive oxygen species. Indeed, butein repressed the TRAIL-mediated activation of NF-kappaB and decreased its transcriptional activity. Our results suggest that butein could sensitize certain human hepatoma cells to TRAIL-induced apoptosis through stimulating its death signaling and by repressing the survival function in these cells.
Laboratory of Immunobiology, Department of Marine Life Science, Jeju National University, Jeju, Republic of Korea.
Dong-Oh
DO
Moon
Mun-Ock
MO
Kim
Yung Hyun
YH
Choi
Gi-Young
GY
Kim
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000473:pathology*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D047188:Chalcones / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D009928:Organ Specificity / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D047188:Chalcones; D016328:NF-kappa B; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D016329:Sp1 Transcription Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C040918:butein; D048049:Extracellular Signal-Regulated MAP Kinases; D020169:Caspases