Inhibition Of Thioredoxin Reductase Research Articles

In-vitro and in-vivo investigations into the carbene-gold anticancer drug candidates NHC*-Au-SCSNMe2 and NHC*-Au-S-GLUC against advanced prostate cancer PC3.

The anticancer drug candidates 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene gold(I) dimethylamino dithiocarbamate and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl-1-thiolate derivative exhibited nanomolar in-vitro activity against prostate cancer cells advanced prostate cancer (PC3) and micromolar inhibition of mammalian thioredoxin reductase. Encouraging maximum tolerable dose experiments led to human prostate cancer subcutaneous xenograft experiments; 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene gold(I) dimethylamino dithiocarbamate and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl-1-thiolate derivative were applied twelve times at two doses in groups of n = 5 PC3 to tumor-bearing NMRI:nu/nu mice. 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene gold(I) dimethylamino dithiocarbamate and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl-1-thiolate derivative at the dose of 10 and 20 mg/kg showed good tolerability, while no significant body weight loss was seen in both groups. In particular, for the drug 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene gold(I) dimethylamino dithiocarbamate the tumor growth inhibition suggested to be dose dependent, reflected by the respective optimal T/C values of 0.45 at the dose of 10 mg/kg and of 0.31 at the dose of 20 mg/kg. By contrast, the 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl-1-thiolate derivative treated groups showed no indication for dose-dependent antitumoral activity, as reflected by the optimal T/C values of 0.44 for the 10 mg/kg and for the 20 mg/kg treated mice. Immunohistochemical experiments involving Ki67 staining of tumor tissue showed that both compounds reduced PC3 cell proliferation against the difficult to treat advanced human prostate tumors derived from PC3.

New cyclometalated gold (III) complex targeting thioredoxin reductase: exploring as cytotoxic agents and mechanistic insights.

A new cyclometalated Au(III) complex highlighting a naphthoquinone-C^N scaffold with formula (NQ-N^C)AuIII(SAd)Cl, 1, in which NQ-N^C: 2-(5-amino-benzo[h]quinolone)-3-(3-methyl-2-butenyl)-1,4-naphthoquinone, HSAd: 1-adamantanethiol, was synthesized and characterized. The interaction of complex 1 with cysteine (CysH) was experimentally and theoretically studied. Complex 1 was more active against MCF-7 and A549 cancer cell lines and less active in a healthy cell (non-tumorigenic cells, MRC-5) than cisplatin. The DNA binding and inhibition of thioredoxin reductase of complex 1 were studied and compared with the molecular docking results. The generation of reactive oxygen species (ROS) and apoptosis of this new complex were also investigated.

Structure-activity relationships in a series of auranofin analogues showing remarkable antiproliferative properties

The antiproliferative properties of a series of structurally-related gold(I) and silver(I) linear complexes inspired to the clinically established gold-based drug auranofin were investigated in A2780 ovarian cancer cells and in their auranofin (A2780/AF-R) and cisplatin (A2780/CDDP-R) resistant counterparts. In A2780 cells and in the cisplatin-resistant subline, gold-based analogues manifested a cytotoxicity profile comparable or superior to auranofin, while the silver-based analogues were less active; both gold and silver complexes overcame cisplatin resistance. Yet, a high degree of cross resistance toward gold analogues was noticed in A2780/AF-R cells. In the same cell line cross-resistance for silver analogues was also observed, though lower. All metal complexes were scrutinized for their ability to inhibit thioredoxin reductase (TrxR), the putative primary target for auranofin: overall, gold compounds were more potent TrxR inhibitors than the corresponding silver compounds, probably, as the consequence of the stronger binding of gold to the active site selenocysteine residue. These results highlight that the thiosugar ligand of auranofin is not essential for cytotoxicity while the nature of the metal center (gold/silver) plays a relevant role in its modulation. In addition, a rather clear correlation was found between cytotoxic potency of tested compounds and their ability to inhibit TrxR activity, being gold compounds more effective than silver analogues. However, the residual TrxR activity, measured in A2780 cells treated with the half-maximal inhibitory concentrations of various metal complexes, resulted far higher than expected. These results suggest that additional cytotoxic mechanisms must be operative. The implications of these results are discussed.

Retraction: Novel Insights into the Synergistic Interaction of a Thioredoxin Reductase Inhibitor and TRAIL: The Activation of the ASK1-ERK-Sp1 Pathway.

Retraction: Novel Insights into the Synergistic Interaction of a Thioredoxin Reductase Inhibitor and TRAIL: The Activation of the ASK1-ERK-Sp1 Pathway.

Antiproliferative Activity of Gold(I) N‐Heterocyclic Carbene and Triphenylphosphine Complexes with Ibuprofen Derivatives as Effective Enzyme Inhibitors

A series of gold(I) complexes of ligand ibuprofen‐alkynyl (but‐3‐yn‐1‐yl 2‐(4‐isobutylphenyl)propanoate, LE) with N‐heterocyclic carbene (LC: 1,3‐dimethylimidazol‐2‐ylidene) and triphenylphosphine (PPh3) ligands with formula (LE)Au (LC) (complex 1) and (LE)Au (PPh3) (complex 2) were synthesized and fully characterized by spectroscopic methods. In order to reveal the cytotoxicity mechanism, the interaction of complex 1 or 2 with cysteine (HCys) has been studied by experimental and density functional theory (DFT) methods. The compounds were investigated for their anticancer activity against MCF‐7, MDAMB 231 breast cancer cells, HT‐29 colon cancer cells and MCF‐10A non‐tumor breast cell line. The results were compared with cisplatin and auranofin as reference drugs. The complex 2 showed more cytotoxic activity than complex 1. The complex 2 was 4.2, 3.7, and 1.7 fold more active than cisplatin against HT‐29, MDA‐MB‐231, MCF‐7 cancer cell lines, respectively. The inhibition of thioredoxin reductase of complexes 1 and 2 including cytosolic (TrxR1) and mitochondrial (TrxR2) thioredoxin reductase and also the inhibition of glutathione reductase (GR) were studied in detail. Moreover, the cellular uptake and reactive oxygen species (ROS) generation of compounds were investigated. Based on the DFT calculations a relationship between the σ‐donor ability of the isolated ligands and cytotoxicity is suggested.

Inhibition of thioredoxin reductase 1 correlates with platinum-based chemotherapeutic induced tissue injury

Platinum-containing drugs (PtDs; e.g. cisplatin, carboplatin, and oxaliplatin) have been widely used as anticancer reagents against various cancers. However, treatment with these drugs results in undesirable adverse effects with unknown mechanisms. Herein, we found a strong correlation between the inhibitory effects of PtDs on cytosolic thioredoxin reductase (TXNRD1) and tissue injury. Of the PtDs tested, cisplatin was found to be the most effective inhibitory PtD against TXRND1, causing the severest kidney injury. The initial inhibition of TXNRD1 in the kidney resulted from cisplatin-induced transcriptional activation of Nrf2-regulated genes including Txnrd1. However, the antioxidant responses in the kidney did not reverse the cisplatin-induced oxidation process. Nephrotoxicity was accompanied with an increase of protein glutathionylation and a cellular thiol redox environment oxidation. These results suggest that the changes of the cellular thiol-dependent redox environment regulated by TXNRD1 is a major event in the adverse effects of cisplatin in kidney.

Potent Inhibition of Thioredoxin Reductase by the Rh Derivatives of Anticancer M(arene/Cp*)(NHC)Cl2Complexes

Metal complexes provide a versatile platform to develop novel anticancer pharmacophores, and they form stable compounds with N-heterocyclic carbene (NHC) ligands, some of which have been shown to inhibit the cancer-related selenoenzyme thioredoxin reductase (TrxR). To expand a library of isostructural NHC complexes, we report here the preparation of RhIII- and IrIII(Cp*)(NHC)Cl2 (Cp* = η5-pentamethylcyclopentadienyl) compounds and comparison of their properties to the RuII- and OsII(cym) analogues (cym = η6-p-cymene). Like the RuII- and OsII(cym) complexes, the RhIII- and IrIII(Cp*) derivatives exhibit cytotoxic activity with half maximal inhibitory concentration (IC50) values in the low micromolar range against a set of four human cancer cell lines. In studies on the uptake and localization of the compounds in cancer cells by X-ray fluorescence microscopy, the Ru and Os derivatives were shown to accumulate in the cytoplasmic region of treated cells. In an attempt to tie the localization of the compounds to the inhibition of the tentative target TrxR, it was surprisingly found that only the Rh complexes showed significant inhibitory activity at IC50 values of ∼1 μM, independent of the substituents on the NHC ligand. This indicates that, although TrxR may be a potential target for anticancer metal complexes, it is unlikely the main target or the sole target for the Ru, Os, and Ir compounds described here, and other targets should be considered. In contrast, Rh(Cp*)(NHC)Cl2 complexes may be a scaffold for the development of TrxR inhibitors.

Further exploration of DVD-445 as a lead thioredoxin reductase (TrxR) inhibitor for cancer therapy: Optimization of potency and evaluation of anticancer potential

A series of analogs of the earlier reported lead compound DVD-445 (thioredoxin reductase inhibitor with anticancer activity) has been synthesized via a modified Ugi reaction and investigated. Seven most potent compounds (with IC50 below 5.00 μM against recombinant rTrxR1 enzyme) were examined for their effect on cell growth and viability, oxidative stress induction and P-glycoprotein (P-gp) inhibition in human glioblastoma cells cell line U87 and its corresponding multidrug resistant (MDR) cell line U87-TxR. Several of these frontrunner compounds were shown to be superior over DVD-445. Besides providing promising candidates for anticancer therapy, our study further validates the small electrophilic Ugi Michael acceptor (UMA) chemotype as efficacious inhibitor of thioredoxin reductase.

Cytotoxic Ag(I) and Au(I) NHC-carbenes bind DNA and show TrxR inhibition

A silver(I) and a gold(I) complex of the fluorescent N-heterocyclic carbenic (NHC) ligand 1-(9-anthracenylmethyl)-3-(3-trimethylsilyl-2-propynil)-benzimidazol-2-ylidene have been synthesized and characterized. These compounds show cytotoxicity in the micromolar range and higher antiproliferative properties than cisplatin (CDDP) against several tumour cell lines such as SW480 (colon), A549 (lung) and HepG2 (liver). Both metal complexes are successfully internalized by SW480 cells being the silver compound the most accumulated. Subsequently, they were evaluated as inhibitors of the selenoenzyme Thioredoxin reductase (TrxR) and as DNA binders. Fluorescence microscopy confirmed that both protein and DNA binding could be involved in the biological activity of the compounds. The silver carbene was the most effective enzyme inhibitor with an IC50 in the nanomolar range. Also, interaction studies with natural double stranded DNA highlight a strong stabilisation of the double helix after binding to the Ag(I) carbene, indicating its potential suitability as dual-targeting anticancer active molecule.

Sanguinarine as a new chemical entity of thioredoxin reductase inhibitor to elicit oxidative stress and promote tumor cell apoptosis

The alteration of redox homeostasis is a hallmark of cancer cells. As a critical player in regulating cellular redox signaling, thioredoxin reductase (TrxR) enzymes are increasingly recognized as attractive targets for anticancer drug development. We reported herein the natural product sanguinarine (SAN) as a potent inhibitor of TrxR with a new chemical scaffold. Inhibition of TrxR leads to accumulation of the oxidized thioredoxin, elicits oxidative stress, and finally promotes apoptosis of cancer cells. Further synthesis of different model compounds of SAN demonstrated that the phenanthridinium unit is responsible for the TrxR inhibition. The core structure of SAN, e.g., the phenanthridinium moiety, is different from those of known TrxR inhibitors, and thus SAN is a new chemical entity of TrxR inhibitors and may serve a lead for further development. In addition, as the phenanthridinium scaffold is widely present in natural products, the disclosure of TrxR inhibition by such unit sheds light in understanding the pharmacological actions of these molecules.

Biological activity of esters of quinoxaline-7-carboxylate 1,4-di-N-oxide against E. histolytica and their analysis as potential thioredoxin reductase inhibitors.

Amoebiasis is caused by the protozoan Entamoeba histolytica that affects millions of people throughout the world. The standard treatment is metronidazole, however, this drug causes several side effects, and is also mutagenic and carcinogenic. Therefore, the search for therapeutic alternatives is necessary. Quinoxaline 1,4-di-N-oxides (QdNOs) derivatives have been shown to exhibit activity against different protozoan. In the present study, the effects of esters of quinoxaline-7-carboxylate 1,4-di-N-oxide (7-carboxylate QdNOs) derivatives on E. histolytica proliferation, morphology, ultrastructure, and oxidative stress were evaluated, also their potential as E. histolytica thioredoxin reductase (EhTrxR) inhibitors was analyzed. In vitro tests showed that 12 compounds from n-propyl and isopropyl series, were more active (IC50 = 0.331 to 3.56μM) than metronidazole (IC50 = 4.5μM). The compounds with better biological activity have a bulky, trifluoromethyl and isopropyl group at R1-, R2-, and R3-position, respectively. The main alterations found in trophozoites treated with some of these compounds included changes in chromatin, cell granularity, redistribution of vacuoles with cellular debris, and an increase in reactive oxygen species. Interestingly, docking studies suggested that 7-carboxylate QdNOs derivatives could interact with amino acid residues of the NADPH-binding domain and/or the redox-active site of EhTrxR. Enzymatic assays demonstrated that selected 7-carboxylate QdNOs inhibits EhTrxR disulfide reductase activity, and diaphorase activity shows that these compounds could act as electron acceptor substrates for the enzyme. Taken together, these data indicate that among the mechanisms involved in the antiamoebic effect of the 7-carboxylate QdNOs derivatives studied, is the induction of oxidative stress and the inhibition of EhTrxR activity.

A thioredoxin reductase inhibitor ethaselen induces growth inhibition and apoptosis in gastric cancer.

Gastric cancer (GC) is the third leading cause of cancer deaths worldwide. Conventional chemotherapy has been proven useful to only a portion of the patients. Previous developed targeted drugs are more effective and tolerable than conventional drugs. Thus the development of novel drugs targeting markers is an urgent task and the main direction for future research. Ethaselen, an inhibitor of thioredoxin reductase (TrxR), has been considered an important anticancer target drug. Previous studies show that it is effective on treating many kinds of cancers. In this paper, we examined that ethaselen effectively inhibited the growth of gastric cancer cells and promoted apoptosis. Organoids were cultured from patient-derived cells in a three-dimension form which are widely used in cancer research to help us understand cancer cells behavior at the sub-organ level and develop novel drugs. We established a drug testing and screening system using GC-derived organoids by recapitulating tumor microenvironment. We confirmed that the TrxR-targeting ethaselen could be a novel and effective drug for gastric cancer treatment.

Sulfocoumarins as dual inhibitors of human carbonic anhydrase isoforms IX/XII and of human thioredoxin reductase

The hypothesis that sulfocoumarin acting as inhibitors of human carbonic anhydrase (CA, EC 4.2.1.1) cancer-associated isoforms hCA IX and – hCA XII is being able to also inhibit thioredoxin reductase was verified and confirmed. The dual targeting of two cancer cell defence mechanisms, i.e. hypoxia and oxidative stress, may both contribute to the observed antiproliferative profile of these compounds against many cancer cell lines. This unprecedented dual anticancer mechanism may lead to a new approach for designing innovative therapeutic agents.

Allylated Curcumin Analog CA6 Inhibits TrxR1 and Leads to ROS-Dependent Apoptotic Cell Death in Gastric Cancer Through Akt-FoxO3a.

BackgroundGastric cancer is one of the leading causes of cancer-related deaths. Allylated monocarbonyl analogs of curcumin (MACs) have been reported to selectively inhibit a broad range of human cancers including gastric cancer. However, the precise molecular mechanisms underlying the inhibitory activities of MACs are not fully known.MethodsIn this study, we examined the anti-tumor activities of an allylated MAC, CA6, on gastric cancer cells and gastric cancer xenograft mouse model. The potential molecular anti-tumor mechanisms of CA6 were also elucidated.ResultsOur data show that CA6 exhibited significant cytotoxicity in gastric cancer cells, which was seen as an induction of G2/M cell cycle arrest and apoptosis. These activities were mediated through an elaboration of ROS levels in gastric cancer cells and induction of endoplasmic reticulum stress. CA6 increased ROS levels through directly binding to and inhibiting thioredoxin reductase R1 (TrxR1). Also, CA6-generated ROS inhibited Akt and activated forkhead O3A (FoxO3a), causing cytotoxicity in gastric cancer cells. Finally, CA6 treatment dose-dependently reduced the growth of gastric cancer xenografts in tumor-bearing mice, which was associated with reduced TrxR1 activity and increased ROS in the tumor.ConclusionIn summary, our studies demonstrate that CA6 inhibited gastric cancer growth by inhibiting TrxR1 and increasing ROS, which in turn activated FoxO3a through suppressing Akt. CA6 is a potential candidate for the treatment of gastric cancer.

Efficient identification of novel anti-glioma lead compounds by machine learning models

Glioblastoma multiforme (GBM) is the most devastating and widespread primary central nervous system tumor. Pharmacological treatment of this malignance is limited by the selective permeability of the blood-brain barrier (BBB) and relies on a single drug, temozolomide (TMZ), thus making the discovery of new compounds challenging and urgent. Therefore, aiming to discover new anti-glioma drugs, we developed robust machine learning models for predicting anti-glioma activity and BBB penetration ability of new compounds. Using these models, we prioritized 41 compounds from our in-house library of compounds, for further in vitro testing against three glioma cell lines and astrocytes. Subsequently, the most potent and selective compounds were resynthesized and tested in vivo using an orthotopic glioma model. This approach revealed two lead candidates, 4m and 4n, which efficiently decreased malignant glioma development in mice, probably by inhibiting thioredoxin reductase activity, as shown by our enzymological assays. Moreover, these two compounds did not promote body weight reduction, death of animals, or altered hematological and toxicological markers, making then good candidates for lead optimization as anti-glioma drug candidates.

FoxO3 reverses 5-fluorouracil resistance in human colorectal cancer cells by inhibiting the Nrf2/TR1 signaling pathway.

5-fluorouracil (5-FU) is widely used in chemotherapy for colorectal cancer (CRC), but a high rate of chemoresistance reduces its effectiveness in clinical treatment. We found remarkably decreased expression of forkhead box 3 (FoxO3) protein, a tumor inhibitor, in 5-FU-resistant SW620 and HCT-8 (SW620/5-FU and HCT-8/5-FU) cells. Moreover, FoxO3 overexpression sensitized SW620/5-FU and HCT-8/5-FU cells to 5-FU. Mechanistically, FoxO3 inhibited the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway by directly binding to Keap1 promoter. Thioredoxin reductase 1 (TR1), a pivotal target gene of Nrf2, was observed to promote 5-FU resistance by reducing intracellular ROS levels. Clinical data also revealed that significant upregulation of TR1 was associated with poor outcome in CRC patients. Auranofin (AUR), a FoxO3 agonist and TR1 inhibitor, enhanced the sensitivity of HCT-8/5-FU and SW620/5-FU cells to 5-FU in vitro and in vivo. Taken together, our results suggest that FoxO3 could reverse 5-FU resistance in CRC via inhibiting the Nrf2/TR1 signaling pathway, and increasing the level of intracellular reactive oxygen species. Chemotherapeutic agents targeting FoxO3 and/or TR1, including AUR, might be promising adjuvant sensitizers to reverse chemoresistance in 5-FU-resistant CRC.

Thioredoxin Reductase Inhibition Attenuates Acute Lung Injury and Enhances the Expression of Angiogenesis-related Genes in Newborn Mice

Thioredoxin Reductase Inhibition Attenuates Acute Lung Injury and Enhances the Expression of Angiogenesis-related Genes in Newborn Mice

Disulfiram Induces Radio-Chemo-Sensitization in Small Cell Lung Cancer and Enhances the Toxicity of Thioredoxin Reductase Inhibition and GSH Depletion

Metabolic reprogramming in cancer cells can increase their dependence on metabolic substrates such as glucose. As such, the vulnerability of cancer cells to glucose deprivation creates an attractive opportunity for therapeutic intervention. Because it is not possible to starve tumors of glucose in vivo, here we sought to identify the mechanisms in glucose deprivation–induced cancer cell death and then designed inhibitor combinations to mimic glucose deprivation–induced cell death. Using metabolomic profiling, we found that cells undergoing glucose deprivation–induced cell death exhibited dramatic accumulation of intracellular l-cysteine and its oxidized dimer, l-cystine, and depletion of the antioxidant GSH. Building on this observation, we show that glucose deprivation–induced cell death is driven not by the lack of glucose, but rather by l-cystine import. Following glucose deprivation, the import of l-cystine and its subsequent reduction to l-cysteine depleted both NADPH and GSH pools, thereby allowing toxic accumulation of reactive oxygen species. Consistent with this model, we found that the glutamate/cystine antiporter (xCT) is required for increased sensitivity to glucose deprivation. We searched for glycolytic enzymes whose expression is essential for the survival of cancer cells with high xCT expression and identified glucose transporter type 1 (GLUT1). Testing a drug combination that co-targeted GLUT1 and GSH synthesis, we found that this combination induces synthetic lethal cell death in high xCT-expressing cell lines susceptible to glucose deprivation. These results indicate that co-targeting GLUT1 and GSH synthesis may offer a potential therapeutic approach for targeting tumors dependent on glucose for survival.

Thioredoxin Reductase Inhibition Sensitizes Erlotinib-resistant Head and Neck Cancer Cells to Radio-Chemotherapy

Thioredoxin Reductase Inhibition Sensitizes Erlotinib-resistant Head and Neck Cancer Cells to Radio-Chemotherapy

Myeloma Cells Addicted to Glutamine for Biomass Production Are Sensitive to Lenalidomide

Introduction We have shown that in myeloma (MM) the immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide, in a CRBN dependent fashion, inhibit thioredoxin reductase and thus increase intracellular oxidative stress as a consequence of peroxide accumulation (Sebastian et al. 2017). Accordingly, we have also shown that CRBN expression alone does not fully correlate with lenalidomide sensitivity, as the cells ability to decompose H2O2 is important - MM cells with lower H2O2 decomposition capacity are more sensitive to IMiDs. We hypothezised that the specific metabolic pathways used by cells for biomass production would influence IMiD sensitivity since they also influence this cellular oxidative capacity. Cellular proteins are key elements of this biomass, and required for the proliferation of MM cells and production of immunoglobulin proteins. Methods We cultured MM cells under various nutrients conditions to understand its effect on cell proliferation and drug responses. Cell viability was assessed by MTT assay, the Luminescent Assay, and direct cell counting. MM cells glycolytic rate was measured using the Seahorse XF analyzer. Western blots were performed to quantify various protein expression levels in MM cells cultured under different nutrients conditions. CRBN CRISPR/Cas9 KO plasmid was used to generate CRBN knockout cells and a lentivirus system was used to over-express CRBN in MM cells. Results MM cells resistant to lenalidomide, but still expressing functional CRBN, show a higher glycolytic pathway use than sensitive cells. We found that the lenalidomide sensitive cell line MM1.S is highly dependent on extracellular glutamine for cell proliferation. In contrast, JJN3, a lenalidomide resistant cells line with wild type CRBN, preferentially consumes glucose. We found that glutamine depletion from culture media completely abolished lenalidomide sensitivity in MM1.S cell line. Western blot analysis revealed that antibody production by MM1.S was primarily dependent on glutamine availability, and that JJN3 antibody production was dependent upon glucose availability. While glutamine depletion from culture medium completely abolished lenalidomide sensitivity in MM1.S cell line, IKZF1, and IKZF3 degradation was unchanged. We further studied the role of CRBN in glutamine dependent cellular biomass protein production using isogenic cell lines (+/- wtCRBN). We found that wtCRBN expressing cells proliferate more and show higher antibody production in the presence of glutamine, over CRBN negative isogenic cell lines. Lenalidomide treatment further increased glutamine dependent antibody production in wtCRBN expressing cells. One possibile explanation is that activation of glutamine catabolism can facilitate protein demethylation via the supplementation α-ketoglutarate (α-KG). Therefore, we tested whether lenalidomide treatment could induce protein demethylation in sensitive cell lines. Western blot probed with mono-methyl lysine antibody showed lenalidomide induced protein demethylation. We further confirmed that protein demethylation, and lenalidomide sensitivity is a consequence of elevated α-KG by treating cells with cell-permeable 5-octyl- α-ketoglutarate which act as a substrate of the lysine demethylases. 5-Octyl-α-ketoglutarate treatment inhibited cell proliferation preferentially in wtCRBN expressing cells, and also enhanced lenalidomide induced sensitivity. Protein demethylation is associated with protein ubiquitination and proteasomal degradation. We thus hypothesize that lenalidomide induced protein demethylation also likely increases proteasome inhibitors sensitivity in MM. Conclusion MM cells with preferential glutamine consumption are likely to be more sensitive to lenalidomide, and extracellular glutamine depletion can induce lenalidomide resistance. MM cells expressing CRBN, but not dependent on glutamine for protein biomass production are more likely to be resistant to lenalidomide. Our study postulates that CRBN protein requirement in lenalidomide sensitivity cells is restricted to high glutamine dependency, and that it is quite likely CRBN has a role in glutamine metabolism. Moreover, MM cells that consume more glutamine are under higher oxidative stress and exhibit less H2O2 decomposition capacity and therefore increasing sensitivity to IMiDs. References Sebastian , S., et al., Blood 2017 129:991-1007 Disclosures Stewart: Ono: Consultancy; Roche: Consultancy; Seattle Genetics: Consultancy; Takeda: Consultancy; Amgen: Consultancy, Research Funding; Bristol Myers-Squibb: Consultancy; Celgene: Consultancy, Research Funding; Ionis: Consultancy; Janssen: Consultancy, Research Funding; Oncopeptides: Consultancy. Bergsagel:Janssen Pharmaceuticals: Consultancy; Ionis Pharmaceuticals: Consultancy; Celgene: Consultancy. Fonseca:AbbVie, Amgen, Bayer, Celgene, Kite, Janssen, Juno, Merck, Pharmacylics, Sanofi, Takeda: Other: Consultant/Advisor; Prognosticatin of MM based on Genetic Categorization by FISH: Patents & Royalties; Adaptive Biotechnologies: Other: Scientific Advisory Board.