Synthetic triterpenoids cooperate with tumor necrosis factor-related apoptosis-inducing ligand to induce apoptosis of breast cancer cells.
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL or Apo2L) has been shown to induce apoptosis specifically in cancer cells while sparing normal tissues. Unfortunately not all cancer cells respond to TRAIL; therefore, TRAIL sensitizing agents are currently being explored. We have identified synthetic triterpenoids, including 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) and its derivative 1-(2-cyano-3,12-dioxooleana-1,9-dien-28-oyl) imidazole (CDDO-Im), which sensitize TRAIL-resistant cancer cells to TRAIL-mediated apoptosis. Here we show that TRAIL-treated T47D and MDA-MB-468 breast cancer cells fail to initiate detectable caspase-8 processing and, consequently, do not initiate TRAIL-mediated apoptosis. Concomitant treatment with CDDO or CDDO-Im reverses the TRAIL-resistant phenotype, promoting robust caspase-8 processing and induction of TRAIL-mediated apoptosis in vitro. The combination of triterpenoids and monoclonal anti-TRAIL receptor-1 (DR4) antibody also induces apoptosis of breast cancer cells in vitro. From a mechanistic standpoint, we show that CDDO and CDDO-Im down-regulate the antiapoptotic protein c-FLIP(L), and up-regulate cell surface TRAIL receptors DR4 and DR5. CDDO and CDDO-Im, when used in combination with TRAIL, have no adverse affect on cultured normal human mammary epithelial cells. Moreover, CDDO-Im and TRAIL are well tolerated in mice and the combination of CDDO-Im and TRAIL reduces tumor burden in vivo in an MDA-MB-468 tumor xenograft model. These data suggest that CDDO and CDDO-Im may be useful for selectively reversing the TRAIL-resistant phenotype in cancer but not normal cells.
Hyer
Marc L
ML
The Burnham Institute, La Jolla, California 92037, USA.
Croxton
Rhonda
R
Krajewska
Maryla
M
Krajewski
Stanislaw
S
Kress
Christina L
CL
Lu
Meiling
M
Suh
Nanjoo
N
Sporn
Michael B
MB
Cryns
Vincent L
VL
Zapata
Juan M
JM
Reed
John C
JC
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009828:Oleanolic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000819:agonists / Q000096:biosynthesis / Q000276:immunology; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
C472829:1-(2-cyano-3,12-dioxooleana-1,9-dien-28-oyl) imidazole; C116817:2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid; D000911:Antibodies, Monoclonal; D051017:Apoptosis Regulatory Proteins; D007093:Imidazoles; D008562:Membrane Glycoproteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; C505640:Tnfrsf10b protein, mouse; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D009828:Oleanolic Acid; C505530:CASP8 protein, human; C505526:Casp8 protein, mouse; D053181:Caspase 8; D020169:Caspases