Sulforaphane sensitizes tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistant hepatoma cells to TRAIL-induced apoptosis through reactive oxygen species-mediated up-regulation of DR5.
Sulforaphane is a chemopreventive agent present in various cruciferous vegetables, including broccoli. Here, we show that treatment with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in combination with subtoxic doses of sulforaphane significantly induces rapid apoptosis in TRAIL-resistant hepatoma cells. Neither TNF-alpha- nor Fas-mediated apoptosis was sensitized in hepatoma cells by cotreatment with sulforaphane, suggesting that sulforaphane can selectively sensitize cells to TRAIL-induced apoptosis but not to apoptosis mediated by other death receptors. We found that sulforaphane treatment significantly up-regulated mRNA and protein levels of DR5, a death receptor of TRAIL. This was accompanied by an increase in the generation of reactive oxygen species (ROS). Pretreatment with N-acetyl-l-cysteine and overexpression of catalase inhibited sulforaphane-induced up-regulation of DR5 and almost completely blocked the cotreatment-induced apoptosis. Furthermore, the sulforaphane-mediated sensitization to TRAIL was efficiently reduced by administration of a blocking antibody or small interfering RNAs for DR5. These results collectively indicate that sulforaphane-induced generation of ROS and the subsequent up-regulation of DR5 are critical for triggering and amplifying TRAIL-induced apoptotic signaling. We also found that sulforaphane can sensitize both Bcl-xL- and Bcl-2-overexpressing hepatoma cells to TRAIL-induced apoptosis, indicating that treatment with a combination of TRAIL and sulforaphane may be a safe strategy for treating resistant hepatomas.
Kim
Heesue
H
Institute for Medical Sciences and Department of Surgery, Ajou University School of Medicine, Suwon, South Korea 442-749.
Kim
Eun Hee
EH
Eom
Young Woo
YW
Kim
Wook-Hwan
WH
Kwon
Taeg Kyu
TK
Lee
Soo Jae
SJ
Choi
Kyeong Sook
KS
D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000096:biosynthesis; D017879:Isothiocyanates; D008113:Liver Neoplasms / Q000188:drug therapy*; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D013454:Sulfoxides; D053221:TNF-Related Apoptosis-Inducing Ligand; D013861:Thiocyanates / Q000008:administration & dosage / Q000494:pharmacology*; D015533:Transcriptional Activation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000494:pharmacology*; D015854:Up-Regulation; D051020:bcl-X Protein / Q000096:biosynthesis
D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; D051034:Inhibitor of Apoptosis Proteins; D017879:Isothiocyanates; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D013454:Sulfoxides; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D013861:Thiocyanates; C505644:Tnfrsf10b protein, rat; C505655:Tnfsf10 protein, rat; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; C016766:sulforaphane