title: Knockdown of Nrf2 enhances autophagy induced by temozolomide in U251             human glioma cell line.
abstract: Glioblastoma multiforme (GBM) and oxidative stress are closely linked. Oxidative             stress affects many signaling pathways and may cause the induction of autophagy.             The NF-E2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1)             signaling pathway is the main pathway responsible for cell defense against oxidative             stress and Nrf2 is a critical transcription factor related with cancer multidrug             resistance. However, the relation between Nrf2 and regulation of autophagy is             not well understood. In this study, we used temozolomide (TMZ), which inhibited             the viability of GBM cells mainly by inducing autophagic cell death and explored             the role of Nrf2 downregulation on autophagy induced by TMZ in GBM cells. In U251-Si-Nrf2             48 h after transfection the protein levels of Nrf2 were significantly downregulated,             while the protein levels of LC3B-II increased by western blot analysis. Knockdown             of Nrf2 also led to a significant increase of autophagic vacuoles and acidic vesicular             organelles (AVOs), revealed by trans-mission electron microscopy (TEM) and acridine             orange (AO) staining using flow cytometry. Collectively, these findings demonstrate             that knockdown of Nrf2 can enhance the basal level of autophagy in the U251 glioma             cell line. Furthermore, after the treatment with TMZ (100 µM) for 3 days, the             U251-Si-Nrf2 transfected cells showed less viability rate by cell counting kit-8             (CCK-8) assay and the levels of autophagy increased obviously through analysis             of western blot and AO staining using flow cytometry. Taken together, our results             suggest that knockdown of Nrf2 may enhance autophagy induced by TMZ in the U251             glioma cell line, which should be further evaluated for novel anticancer activity.
authors.affiliation: Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Han-Dong
authors.initials: HD
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Zhu
authors.forename: Zi-Xiang
authors.initials: ZX
authors.lastname: Cong
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Xiang-Jun
authors.initials: XJ
authors.lastname: Ji
authors.forename: Hao
authors.initials: H
authors.lastname: Pan
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Wang
authors.forename: Wan-Chun
authors.initials: WC
authors.lastname: Li
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015536:Down-Regulation; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005910:Glioma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D051267:NF-E2-Related Factor 2 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D000077204:Temozolomide; D014407:Tumor Cells, Cultured
chemical_list: D018906:Antineoplastic Agents, Alkylating; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D034741:RNA, Small Interfering; D003606:Dacarbazine; D000077204:Temozolomide