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.
Moon
Dong-Oh
DO
Laboratory of Immunobiology, Department of Marine Life Science, Jeju National University, Jeju, Republic of Korea.
Kim
Mun-Ock
MO
Choi
Yung Hyun
YH
Kim
Gi-Young
GY
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