Cancer related mutations in
            <i>NRF2</i>
            impair its recognition by Keap1-Cul3 E3 ligase and promote malignancy

Shibata, Tatsuhiro; Ohta, Tsutomu; Tong, Kit I.; Kokubu, Akiko; Odogawa, Reiko; Tsuta, Koji; Asamura, H.; Yamamoto, Masayuki; Hirohashi, Setsuo

doi:10.1073/pnas.0806268105

Cited by 660 publications

(689 citation statements)

References 40 publications

Supporting

Mentioning

651

Contrasting

Unclassified

Order By: Relevance

“…1C). 16 Both these motifs, evolutionarily conserved, bind to the Kelch domain in Keap1. Analysis of the predicted effects of these changes (MUpro software, at http://www.ics.uci.…”

Section: Resultsmentioning

confidence: 99%

Nrf2, but not β‐catenin, mutation represents an early event in rat hepatocarcinogenesis

et al. 2015

View full text Add to dashboard Cite

Hepatocellular carcinoma (HCC) develops through a multistage process, but the nature of the molecular changes associated with the different steps, the very early ones in particular, is largely unknown. Recently, dysregulation of the NRF2/KEAP1 pathway and mutations of these genes have been observed in experimental and human tumors, suggesting their possible role in cancer development. To assess whether Nrf2/Keap1 mutations are early or late events in HCC development, we investigated their frequency in the rat Resistant Hepatocyte model, consisting of the administration of diethylnitrosamine followed by a brief exposure to 2-acetylaminofluorene. This model enables the dissection of all stages of hepatocarcinogenesis. We found that Nrf2/Keap1 mutations were present in 71% of early preneoplastic lesions and in 78.6% and 59.3% of early and advanced HCCs, respectively. Mutations of Nrf2 were more frequent, missense, and located in the Nrf2-Keap1 binding region. Mutations of Keap1 occurred at a much lower frequency in both preneoplastic lesions and HCCs and were mutually exclusive with those of Nrf2. Functional in vitro and in vivo studies showed that Nrf2 silencing inhibited the ability of tumorigenic rat cells to grow in soft agar and to form tumors. Unlike Nrf2 mutations, those of Ctnnb1, which are frequent in human HCC, were a later event as they appeared only in fully advanced HCCs (18.5%). Conclusion: In the Resistant Hepatocyte model of hepatocarcinogenesis the onset of Nrf2 mutations is a very early event, likely essential for the clonal expansion of preneoplastic hepatocytes to HCC, while Ctnnb1 mutations occur only at very late stages. Moreover, functional experiments demonstrate that Nrf2 is an oncogene critical for HCC progression and development. (HEPATOLOGY 2015;62:851-862) See Editorial on Page 677 H epatocellular carcinoma (HCC) is the third most frequent cause of cancer-related deaths worldwide. 1 Unfortunately, our knowledge of the genomic alterations implicated in HCC initiation and progression is still fragmentary. Moreover, different from other solid tumors, no driving genetic alteration to which tumor cells are addicted and that can be effectively targeted has ever been identified. In this scenario, HCC is probably one of the tumor types where a more complete understanding of the underlying genetic alterations could have a major impact on the development of new treatment strategies. Also known as NFE2L2, NRF2 is of particular interest as conflicting results have been reported concerning the role of the NRF2/KEAP1 pathway in cancer development. 2 It is a master transcriptional activator of genes encoding enzymes that protect cells from oxidative stress and

show abstract

“…1C). 16 Both these motifs, evolutionarily conserved, bind to the Kelch domain in Keap1. Analysis of the predicted effects of these changes (MUpro software, at http://www.ics.uci.…”

Section: Resultsmentioning

confidence: 99%

Nrf2, but not β‐catenin, mutation represents an early event in rat hepatocarcinogenesis

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Importantly, NRF2 activation and KEAP1 inactivation mutations leading to permanent constitutive adaptive activation of the NRF2 pathway are increasingly observed in cancers [8,9,10] and other diseases [11,12]. It is well known that several therapeutic strategies, for example anticancer radiotherapy and chemotherapy, largely depend on ROS manipulation to induce cytotoxicity.…”

Section: Introductionmentioning

confidence: 99%

NRF2 inhibition causes repression of ATM and ATR expression leading to aberrant DNA Damage Response

Khalil¹,

Deeni²

2015

Biodiscovery

View full text Add to dashboard Cite

Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a master regulator of the antioxidant response (AR) pathway and functions as a transcription factor for basal and oxidative stress-induced expression of a battery of detoxification enzymes and cytoprotective genes. Recent evidence has also demonstrated a role of NRF2 in driving resistance of numerous cancers to chemotherapeutic agents. ATM and ATR are serine/threonine kinases that are activated following DNA damage and function as central components of DNA Damage Response (DDR) pathway. Activities of these kinases cause cell cycle arrest and activate DNA repair signals leading to cytoprotection against genotoxic agents. In this study, we elucidated the roles of ATM-and ATR-dependent DDR and NRF2-mediated AR pathways in promoting cytoprotection following cisplatin challenge in ovarian cancer cell line models. We also determined whether these pathways were inter-dependent for full activation following genotoxic insults and as such demonstrated crosstalk in their signaling mechanism to elicit cytoprotective pathways. Treatment with cisplatin caused NRF2 induction and generation of reactive oxygen species (ROS) that caused cytotoxicity in ovarian cancer cells. This was attenuated by the ROS scavenger N-Acetyl cysteine, implicating NRF2 function in cytoprotection against cisplatin. Treatment with retinoic acid (RA) caused down regulation of NRF2, disruption of AR pathway, significant accumulation of ROS and enhanced cisplatin cytotoxicity. Interestingly, RA treatment also led to repression of total ATM and ATR proteins and aberrant DDR activation following cisplatin challenge. In order to determine whether the RA induced ATM and ATR repression was dependent on NRF2 inhibition, we silenced NRF2 using SiRNA. This caused transcriptional repression of both ATM and ATR expression as determined by their promoter driven luciferase assays. Thus, NRF2 inhibition led to DDR suppression by down-regulating ATM and ATR that led to enhanced cytotoxicity. These findings demonstrate mechanism of crosstalk between the AR and the DDR pathways and extend the scope of NRF2 in promoting cancer therapeutic resistance.

show abstract

“…By the same token, mutations in Nrf2 can disrupt Keap1-dependent repression and result in overexpression of Nrf2. Somatic mutations in the coding region of Nrf2 that allow Nrf2 to escape repression by the Keap1-Cullin3 E3 ubiquitin ligase were found in lung (11/103; 10.7%) and head and neck (3/12, 10.7%) tumors (25). In a similar study, Nrf2 mutations were found in esophagus (8/70; 11.4%), skin (1/17; 6.3%), lung (10/125; 8.0%), and larynx (3/23; 13.0%) tumors (26).…”

mentioning

confidence: 99%

Brusatol enhances the efficacy of chemotherapy by inhibiting the Nrf2-mediated defense mechanism

Ren

Villeneuve

Jiang

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

565

506

View full text Add to dashboard Cite

The major obstacle in cancer treatment is the resistance of cancer cells to therapies. Nrf2 is a transcription factor that regulates a cellular defense response and is ubiquitously expressed at low basal levels in normal tissues due to Keap1-dependent ubiquitination and proteasomal degradation. Recently, Nrf2 has emerged as an important contributor to chemoresistance. High constitutive expression of Nrf2 was found in many types of cancers, creating an environment conducive for cancer cell survival. Here, we report the identification of brusatol as a unique inhibitor of the Nrf2 pathway that sensitizes a broad spectrum of cancer cells and A549 xenografts to cisplatin and other chemotherapeutic drugs. Mechanistically, brusatol selectively reduces the protein level of Nrf2 through enhanced ubiquitination and degradation of Nrf2. Consequently, expression of Nrf2-downstream genes is reduced and the Nrf2-dependent protective response is suppressed. In A549 xenografts, brusatol and cisplatin cotreatment induced apoptosis, reduced cell proliferation, and inhibited tumor growth more substantially when compared with cisplatin treatment alone. Additionally, A549-K xenografts, in which Nrf2 is expressed at very low levels due to ectopic expression of Keap1, do not respond to brusatol treatment, demonstrating that brusatol-mediated sensitization to cisplatin is Nrf2 dependent. Moreover, a decrease in drug detoxification and impairment in drug removal may be the primary mechanisms by which brusatol enhances the efficacy of chemotherapeutic drugs. Taken together, these results clearly demonstrate the effectiveness of using brusatol to combat chemoresistance and suggest that brusatol can be developed into an adjuvant chemotherapeutic drug.

show abstract

Cancer related mutations in NRF2 impair its recognition by Keap1-Cul3 E3 ligase and promote malignancy

Cited by 660 publications

References 40 publications

Nrf2, but not β‐catenin, mutation represents an early event in rat hepatocarcinogenesis

Nrf2, but not β‐catenin, mutation represents an early event in rat hepatocarcinogenesis

NRF2 inhibition causes repression of ATM and ATR expression leading to aberrant DNA Damage Response

Brusatol enhances the efficacy of chemotherapy by inhibiting the Nrf2-mediated defense mechanism

Contact Info

Product

Resources

About