Inhibition of the Nrf2-TrxR Axis Sensitizes the Drug-Resistant Chronic Myelogenous Leukemia Cell Line K562/G01 to Imatinib Treatments

Abstract

Nuclear factor erythroid 2-related factor 2 (Nrf2) is involved in tumor drug resistance, but its role in imatinib resistance of chronic myeloid leukemia (CML) remains elusive. We aimed to investigate the effects of Nrf2 on drug sensitivity, thioredoxin reductase (TrxR) expression, reactive oxygen species (ROS) production, and apoptosis induction in imatinib-resistant CML K562/G01 cells and explored their potential mechanisms. Stable K562/G01 cells with knockdown of Nrf2 were established by infection of siRNA-expressing lentivirus. The mRNA and protein expression levels of Nrf2 and TrxR were determined by real-time quantitative polymerase chain reaction and western blot, respectively. ROS generation and apoptosis were assayed by flow cytometry, while drug sensitivity was measured by the Cell Counting Kit-8 assay. Imatinib-resistant K562/G01 cells had higher levels of Nrf2 expression than the parental K562 cells at both mRNA and protein levels. Expression levels of Nrf2 and TrxR were positively correlated in K562/G01 cells. Knockdown of Nrf2 in K562/G01 cells enhanced the intracellular ROS level, suppressed cell proliferation, and increased apoptosis in response to imatinib treatments. Nrf2 expression contributes to the imatinib resistance of K562/G01 cells and is positively correlated with TrxR expression. Targeted inhibition of the Nrf2-TrxR axis represents a potential therapeutic approach for imatinib-resistant CML.

Discovery of hydroxytyrosol as thioredoxin reductase 1 inhibitor to induce apoptosis and G1/S cell cycle arrest in human colorectal cancer cells via ROS generation

“…As both Trx and TrxR1 have been reported to be upregulated in numerous human cancer types, including leukemia, lung cancer, breast cancer and colorectal cancer among others, and be associated with increased tumor growth, drug resistance and poor patient prognosis, the thioredoxin system has been recognized as an attractive target for anticancer drug development (4,(6)(7)(8)(9)(10)40). This system plays a role in maintaining H 2 O 2 levels in cells via the conversion of H 2 O 2 to H 2 O. Trx contains two adjacent thiols in its reduced form that are converted to a disulfide bond in the oxidized form (39).…”

“…Mammalian thioredoxin (Trx) reductase 1 (TrxR1) is a selenoprotein that functions to maintain redox homeostasis in cells via transferring electrons from NADPH to its substrate Trx (4,5). Both Trx and TrxR1 are reported to be upregulated in CRC cells and have been associated with poor prognosis and resistance to chemotherapy (6)(7)(8)(9). Increasing evidence has suggested that TrxR1 is involved in multiple steps of tumorigenesis (10)(11)(12)(13)(14).…”

The Role of the Thioredoxin Detoxification System in Cancer Progression and Resistance

“…Nrf2 expression was significantly higher in cisplatin-resistant and non-responding patients than in good responders ( Roh et al, 2017b ). Chronic myeloid leukemia (CML) cancer cells, resistant to imatinib, express higher levels of Nrf2 and TrxR, involved in protecting cancer cells from the harmful effects of the drug ( Xu et al, 2019 ). Silencing of Nrf2 sensitizes the CML imatinib-resistant cells, ovarian cisplatin-resistant cancer cells, and lung doxorubicin-resistant cancer cells ( Cho et al, 2008 ; Xu et al, 2019 ).…”

“…Chronic myeloid leukemia (CML) cancer cells, resistant to imatinib, express higher levels of Nrf2 and TrxR, involved in protecting cancer cells from the harmful effects of the drug ( Xu et al, 2019 ). Silencing of Nrf2 sensitizes the CML imatinib-resistant cells, ovarian cisplatin-resistant cancer cells, and lung doxorubicin-resistant cancer cells ( Cho et al, 2008 ; Xu et al, 2019 ). Mutations in the KEAP1 gene, causing destabilized Nrf2/Keap1 relation and excessive Nrf2 activity, are associated with occurrence and chemoresistance in leukemia, lung, breast, colon, gastric, and liver cancer ( Padmanabhan et al, 2006 ; Hayes and McMahon, 2009 ; Rushworth and Macewan, 2011 ; Yoo et al, 2012 ; Ganan-Gomez et al, 2013 ).…”

Evaluation of Proanthocyanidins from Kiwi Leaves (Actinidia chinensis) against Caco-2 Cells Oxidative Stress through Nrf2-ARE Signaling Pathway

“…The importance of studying the nuclear factor erythroid 2-related factor 2 (Nrf2) as a cellular antioxidant marker comes from its high ability to bind with Kelch-like ECH-associated protein (Keap1, the cysteine-based mammalian intracellular sensor for electrophiles and oxidants) in the cytoplasm, under normal circumstances [ 17 ]. Upon oxidative stress, the Nrf2 migrates to the nucleus, and combines with the antioxidant response element (ARE), which can upregulate the transcription of cell defense-related genes, including drug metabolizers, detoxifying enzymes, and antioxidant proteins [ 18 ]. Several studies have reported that the Nrf2 signaling pathway plays a crucial role in the activation of cytoprotective genes in response to xenobiotics, and protecting cells against oxidative stress.…”