Nrf2 activity as a potential biomarker for the pan-epigenetic anticancer agent, RRx-001.
Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulatory transcription factor that plays an important role in the antioxidant response pathway against anticancer drug-induced cytotoxic effects. RRx-001 is a new anticancer agent that generates reactive oxygen and nitrogen species, and leads to epigenetic alterations in cancer cells. Here we report the RRx-001 mediated nuclear translocation of Nrf2 and the activation of expression of its downstream enzymes HO-1 and NQO1 in tumor cells. Inhibition of intrinsic Nrf2 expression by Nrf2-specific siRNA increased cell sensitivity to RRx-001. Molecular imaging of tumor cells co-expressing pARE-Firefly luciferase and pCMV-Renilla luciferase-mRFP in vitro and in vivo in mice revealed that RRx-001 significantly increased ARE-FLUC signal in cells in a dose- and time-dependent manner, suggesting that RRx-001 is an effective activator of the Nrf2-ARE signaling pathway. The pre-treatment level of ARE-FLUC signal in cells, reflecting basal activity of Nrf2, negatively correlated with the tumor response to RRx-001. The results support the concept that RRx-001 activates Nrf2-ARE antioxidant signaling pathways in tumor cells. Hence measurement of Nrf2-mediated activation of downstream target genes through ARE signaling may constitute a useful molecular biomarker for the early prediction of response to RRx-001 treatment, and thereby guide therapeutic decision-making.
Department of Radiation Oncology Stanford University Medical Center Stanford, CA 94305, USA.
Shoucheng
S
Ning
Department of Radiology Stanford University Medical Center Stanford, CA 94304, USA.
Thillai Veerapazham
TV
Sekar
EpicentRx, Inc., Mountain View, CA 94041, USA.
Jan
J
Scicinski
EpicentRx, Inc., Mountain View, CA 94041, USA.
Bryan
B
Oronsky
Department of Urology Stanford University Medical Center Stanford, CA 94305, USA.
Donna M
DM
Peehl
Department of Radiation Oncology Stanford University Medical Center Stanford, CA 94305, USA.
Susan J
SJ
Knox
Department of Radiology Stanford University Medical Center Stanford, CA 94304, USA.
Ramasamy
R
Paulmurugan
D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry*; D001384:Azetidines / Q000737:chemistry*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D044127:Epigenesis, Genetic; D005786:Gene Expression Regulation; D051547:Heme Oxygenase-1 / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D049449:Luminescence; D008164:Luminescent Proteins / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D009368:Neoplasm Transplantation; D009574:Nitro Compounds / Q000737:chemistry*; D018384:Oxidative Stress; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D000097573:Red Fluorescent Protein
D000970:Antineoplastic Agents; D001384:Azetidines; D014408:Biomarkers, Tumor; D051547:Heme Oxygenase-1; D008156:Luciferases; D008164:Luminescent Proteins; D008565:Membrane Proteins; D016660:NAD(P)H Dehydrogenase (Quinone); D051267:NF-E2-Related Factor 2; D009574:Nitro Compounds; D034741:RNA, Small Interfering; D000097573:Red Fluorescent Protein; C495636:Nfe2l2 protein, mouse; C577469:RRx-001; C496542:Hmox1 protein, mouse; C491732:Nqo1 protein, mouse
ARE; Nrf2; biomarker; cancer; oxidative stress