High levels of Nrf2 determine chemoresistance in type II endometrial cancer.
Type II endometrial cancer, which mainly presents as serous and clear cell types, has proved to be the most malignant and recurrent carcinoma among various female genital malignancies. The transcription factor Nrf2 was first described as having chemopreventive activity. Activation of the Nrf2-mediated cellular defense response protects cells against the toxic and carcinogenic effects of environmental insults by upregulating an array of genes that detoxify reactive oxygen species and restore cellular redox homeostasis. However, the cancer-promoting role of Nrf2 has recently been revealed. Nrf2 is constitutively upregulated in several types of human cancer tissues and cancer cell lines. Furthermore, inhibition of Nrf2 expression sensitizes cancer cells to chemotherapeutic drugs. In this study, the constitutive level of Nrf2 was compared in different types of human endometrial tumors. It was found that Nrf2 was highly expressed in endometrial serous carcinoma (ESC), whereas complex hyperplasia and endometrial endometrioid carcinoma (EEC) had no or marginal expression of Nrf2. Likewise, the ESC-derived SPEC-2 cell line had a higher level of Nrf2 expression and was more resistant to the toxic effects of cisplatin and paclitaxel than the Ishikawa cell line, which was generated from EEC. Silencing of Nrf2 rendered SPEC-2 cells more susceptible to chemotherapeutic drugs, whereas it had a limited effect on Ishikawa cells. Inhibition of Nrf2 expression by overexpressing Keap1 sensitized SPEC-2 cells or SPEC-2-derived xenografts to chemotherapeutic treatments using both cell culture and severe combined immunodeficient mouse models. Collectively, we provide a molecular basis for the use of Nrf2 inhibitors to increase the efficacy of chemotherapeutic drugs and to combat chemoresistance, the biggest obstacle in chemotherapy.
Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona 85724, USA.
Tao
T
Jiang
Ning
N
Chen
Fei
F
Zhao
Xiao-Jun
XJ
Wang
Beihua
B
Kong
Wenxin
W
Zheng
Donna D
DD
Zhang
D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D018269:Carcinoma, Endometrioid / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D002945:Cisplatin / Q000494:pharmacology; D018284:Cystadenocarcinoma, Serous / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D019008:Drug Resistance, Neoplasm; D016889:Endometrial Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D051379:Mice; D016513:Mice, SCID; D008875:Middle Aged; D051267:NF-E2-Related Factor 2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017239:Paclitaxel; D002945:Cisplatin