Aldo-keto Reductase 1C3 Inhibitors Research Articles

Inhibition of aldo-keto reductase 1C3 overcomes gemcitabine/cisplatin resistance in bladder cancer

Systemic chemotherapy with gemcitabine and cisplatin (GC) has been used for the treatment of bladder cancer in which androgen receptor (AR) signaling is suggested to play a critical role. However, its efficacy is often limited, and the prognosis of patients who develop resistance is extremely poor. Aldo-keto reductase 1C3 (AKR1C3), which is responsible for the production of a potent androgen, 5α-dihydrotestosterone (DHT), by the reduction of 5α-androstane-3α,17β-dione (5α-Adione), has been attracting attention as a therapeutic target for prostate cancer that shows androgen-dependent growth. By contrast, the role of AKR1C3 in bladder cancer remains unclear. In this study, we examined the effect of an AKR1C3 inhibitor on androgen-dependent proliferation and GC sensitivity in bladder cancer cells. 5α-Adione treatment induced the expression of AR and its downstream factor ETS-domain transcription factor (ELK1) in both T24 cells and newly established GC-resistant T24GC cells, while it did not alter AKR1C3 expression. AKR1C3 inhibitor 2j significantly suppressed 5α-Adione-induced AR and ELK1 upregulation, as did an AR antagonist apalutamide. Moreover, the combination of GC and 2j in T24GC significantly induced apoptotic cell death, suggesting that 2j could enhance GC sensitivity. Immunohistochemical staining in surgical specimens further revealed that strong expression of AKR1C3 was associated with significantly higher risks of tumor progression and cancer-specific mortality in patients with muscle-invasive bladder cancer. These results suggest that AKR1C3 inhibitors as adjunctive agents enhance the efficacy of GC therapy for bladder cancer.

In silico study of novel alpha tocopheroids as effective inhibitors of aldo-keto reductase 1c3 (AKR1C3) enzyme

Aldo-keto reductase 1C3 (AKR1C3) is a monomeric enzyme expressed in steroidogenic tissues such as the testis, prostate, uterus, and breast. Overexpression of this AKR1C3 is associated with vast cancers such as breast, colon, colorectal, endometrial, prostate, and acute myeloid leukaemia. Regarding the treatment of castration-resistant prostate cancer, breast cancer, and acute myeloid leukaemia, AKR1C3 inhibitors may offer clear advantages over currently available therapies. Thus, discovering novel and specific AKR1C3 inhibitors is a promising way to obstruct drug resistance in cancer. Derivatives of alpha-tocopherol and alpha-tocopheroids were selected as possible therapeutics to act as AKR1C3 inhibitors. The precise targets of several ligands were determined using computational screening methods. The molecular structure of AKR1C3 and its ligands were used as the foundation for in silico predictions, modelling, and dynamic simulations. Compounds were selected based on their biological properties and filtered according to their ADMET and drug-likeness properties. Additionally, simulations of all-atom molecular dynamics on AKR1C3 with the cleared compounds revealed stability over the simulated trajectories of 100 ns. When seen collectively, alpha-tocospiro A may be considered prospective AKR1C3 inhibitors for creating anticancer therapies. Communicated by Ramaswamy H. Sarma

Aldo-Keto Reductase 1C3 Inhibitor Prodrug Improves Pharmacokinetic Profile and Demonstrates In Vivo Efficacy in a Prostate Cancer Xenograft Model.

Aldo-keto reductase 1C3 (AKR1C3) is overexpressed in castration-resistant prostate cancer where it acts to drive proliferation and aggressiveness by producing androgens. The reductive action of the enzyme leads to chemoresistance development against various clinical antineoplastics across a range of cancers. Herein, we report the continued optimization of selective AKR1C3 inhibitors and the identification of 5r, a potent AKR1C3 inhibitor (IC50 = 51 nM) with >1216-fold selectivity for AKR1C3 over closely related isoforms. Due to the cognizance of the poor pharmacokinetics associated with free carboxylic acids, a methyl ester prodrug strategy was pursued. The prodrug 4r was converted to free acid 5r in vitro in mouse plasma and in vivo. The in vivo pharmacokinetic evaluation revealed an increase in systemic exposure and increased the maximum 5r concentration compared to direct administration of the free acid. The prodrug 4r demonstrated a dose-dependent effect to reduce the tumor volume of 22Rv1 prostate cancer xenografts without observed toxicity.

Development of Biaryl-Containing Aldo-Keto Reductase 1C3 (AKR1C3) Inhibitors for Reversing AKR1C3-Mediated Drug Resistance in Cancer Treatment.

Aldo-keto reductase 1C3 (AKR1C3) is correlated with tumor development and chemotherapy resistance. The catalytic activity of the enzyme has been recognized as one of the important factors in inducing anthracycline (ANT) resistance in cancer cells. Inhibition of AKR1C3 activity may provide a promising approach to restore the chemosensitivity of ANT-resistant cancers. Herein, a series of biaryl-containing AKR1C3 inhibitors has been developed. The best analogue S07-1066 selectively blocked AKR1C3-mediated reduction of doxorubicin (DOX) in MCF-7 transfected cell models. Furthermore, co-treatment of S07-1066 significantly synergized DOX cytotoxicity and reversed the DOX resistance in MCF-7 cells overexpressing AKR1C3. The potential synergism of S07-1066 over DOX cytotoxicity was demonstrated in vitro and in vivo. Our findings indicate that inhibition of AKR1C3 potentially enhances the therapeutic efficacy of ANTs and even suggests that AKR1C3 inhibitors may serve as effective adjuvants to overcome AKR1C3-mediated chemotherapy resistance in cancer treatment.

MP20-16 NOVEL FUNCTION OF PTUPB IN AKR1C3/AR/AR-V7 AXIS INHIBITION AND ENZALUTAMIDE SENSITIZATION IN ADVANCED PROSTATE CANCER

You have accessJournal of UrologyCME1 Apr 2023MP20-16 NOVEL FUNCTION OF PTUPB IN AKR1C3/AR/AR-V7 AXIS INHIBITION AND ENZALUTAMIDE SENSITIZATION IN ADVANCED PROSTATE CANCER Joy Yang, Pengfei Xu, Bo Chen, Shu Ning, Hans Adomat, Sung-Hee Hwang, Allen Gao, Martin Gleave, Bruce Hammock, Christopher Evans, and Chengfei Liu Joy YangJoy Yang More articles by this author , Pengfei XuPengfei Xu More articles by this author , Bo ChenBo Chen More articles by this author , Shu NingShu Ning More articles by this author , Hans AdomatHans Adomat More articles by this author , Sung-Hee HwangSung-Hee Hwang More articles by this author , Allen GaoAllen Gao More articles by this author , Martin GleaveMartin Gleave More articles by this author , Bruce HammockBruce Hammock More articles by this author , Christopher EvansChristopher Evans More articles by this author , and Chengfei LiuChengfei Liu More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003245.16AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The steroidogenic enzyme Aldo-keto Reductase 1C3 (AKR1C3) is a major factor that contributes to the progression of castration-resistant prostate cancer (CRPC) and treatment failure. However, none of the available AKR1C3 inhibitors has shown promising results in clinical settings. Thus, there is an unmet need to develop superior AKR1C3 inhibitors for clinical testing. METHODS: PTUPB was synthesized by linking two pharmacophores, celecoxib and TPPU. In vitro and in vivo pharmacological activities of PTUPB in combination with enzalutamide were evaluated in several enzalutamide-resistant cell lines, conditional reprogrammed cell cultures, and patient-derived organoid models. The mechanism of action of PTUPB was examined via RNA sequence analysis, immunoblot analysis, co-immunoprecipitation, steroid measurement, and enzyme activity assays. Animal studies using PTUPB in combination with enzalutamide were performed in the castration-relapse VCaP tumor model. RESULTS: AKR1C3 levels are reciprocally regulated by the full-length androgen receptor (AR-FL) by binding to the distal enhancer region of AKR1C3. A novel function of PTUPB in AKR1C3 inhibition was discovered: at the same dose (0.5 µM) PTUPB suppressed the AKR1C3 activity more than indomethacin (60% vs. 40%) and celeboxib (60% vs. 0, p<0.05). And at the same dose (20 µM), PTUPB was more effective than indomethacin (98% vs. 22% of inhibition, p<0.05) and celecoxib (98% vs. 60% inhibition, p<0.05) in inhibiting CRPC cell growth. PTUPB synergizes with enzalutamide treatment for tumor suppression and gene signature regulation. Combination treatment with PTUPB and enzalutamide provides benefits by blocking AR and its variant (AR-V7) signaling, which inhibits the growth of VCaP castration-relapse tumors with 2.8-fold more inhibition (p<0.05) in tumor weights between the single (PTUPB) and combination treatments (Enza+PTUPB). There was also more inhibition in the growth of the patient-derived xenograft organoids by PTUPB alone or in combination with Enza. CONCLUSIONS: Targeting the ARK1C3/AR/AR-V7 axis with PTUPB and enzalutamide may overcome drug resistance to AR signaling inhibitors in advanced prostate cancer. Source of Funding: This work was supported in part by grants NIH/NCI R37CA249108 (C. Liu) and R01CA251253 (C. Liu) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e281 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Joy Yang More articles by this author Pengfei Xu More articles by this author Bo Chen More articles by this author Shu Ning More articles by this author Hans Adomat More articles by this author Sung-Hee Hwang More articles by this author Allen Gao More articles by this author Martin Gleave More articles by this author Bruce Hammock More articles by this author Christopher Evans More articles by this author Chengfei Liu More articles by this author Expand All Advertisement PDF downloadLoading ...

Development of highly potent and specific AKR1C3 inhibitors to restore the chemosensitivity of drug-resistant breast cancer

Aldo-keto reductase 1C3 (AKR1C3) is overexpressed in multiple hormone related cancers, such as breast and prostate cancer, and is correlated with tumor development and aggressiveness. As a phase I biotransformation enzyme, AKR1C3 catalyzes the metabolic processes that lead to resistance to anthracyclines, the “gold standard” for breast cancer treatment. Novel approaches to restore the chemotherapy sensitivity of breast cancer are urgently required. Herein, we developed a new class of AKR1C3 inhibitors that demonstrated potent inhibitory activity and exquisite selectivity for closely related isoforms. The best derivative 27 (S19–1035) exhibits an IC50 value of 3.04 nM for AKR1C3 and >3289-fold selectivity over other isoforms. We determined the co-crystal structures of AKR1C3 with three of the inhibitors, providing a solid foundation for further structure-based drug optimization. Co-administration of these AKR1C3 inhibitors significantly reversed the doxorubicin (DOX) resistance in a resistant breast cancer cell line. Therefore, the novel AKR1C3 specific inhibitors developed in this work may serve as effective adjuvants to overcome DOX resistance in breast cancer treatment.

Discovery of Novel Aldo-Keto Reductase 1C3 Inhibitors as Chemotherapeutic Potentiators for Cancer Drug Resistance.

As a crucial target which is overexpressed in a variety of cancers, aldo-keto reductase 1C3 (AKR1C3) confers chemotherapeutic resistance to many clinical agents. However, a limited number of AKR1C3-selective inhibitors are applied clinically, which indicates the importance of identifying active compounds. Herein, we report the discovery, synthesis, and evaluation of novel and potent AKR1C3 inhibitors with structural diversity. Molecular dynamics simulations of these active compounds provide reasonable clarification of the interpreted biological data. Moreover, we demonstrate that AKR1C3 inhibitors have the potential to be superior therapeutic agents for re-sensitizing drug-resistant cell lines to chemotherapy, especially the pan-AKR1C inhibitor S07-2010. Our study identifies new structural classes of AKR1C3 inhibitors and enriches the structural diversity, which facilitates the future rational design of inhibitors and structural optimization. Moreover, these compounds may serve as promising therapeutic adjuvants toward new therapeutics for countering drug resistance.

Abstract 5691: Preclinical evaluation of TFX05-01, a selective AKR1C3- targeted prodrug for solid tumor

Abstract Objective: Aldo-keto reductase 1C3 (AKR1C3), is a member of the aldo-keto reductase superfamily, catalyzing the NADP(H)-dependent stereospecific reduction of various aldehydes and ketones. AKR1C3 is overexpressed in a variety of cancer cells, including hepatocellular carcinoma (HCC), castration-resistant prostate cancer (CRPC), and leukemia cells. This study is to investigate the in vitro and in vivo antitumor activity of TFX05-01, a selective AKR1C3-activated anticancer prodrug, in preclinical models of AKR1C3 overexpressing cells. The studies provide solid foundation for nomination of TFX05-01 for clinical trials. Method: Enzymatic activation of TFX05-01 was investigated in vitro using recombinant human AKR1C3. Cellular anti-proliferative activity was evaluated with a range of AKR1C3 overexpressed or low expressed cell lines. The in vivo antitumor activity was evaluated in various CDX mouse models with high expression of AKR1C3, including HepG2 and castration-resistant prostate VCaP, as well as PDX leukemia models Result: TFX05-01 is a prodrug which selectively releases a DNA alkylating agent (TFX05-01A) upon exposure to AKR1C3. TFX05-01 inhibited cell proliferation in several AKR1C3 overexpressed HCC cell lines with an IC50 ≤ 100 nM. In contrast, TFX05-01 showed much lower anti-proliferative activity in low or no AKR1C3 expressed cells with an IC50 value greater than 1 μM. The cytotoxic potency of TFX05-01 in cancer cells correlates with the level of AKR1C3 expression, and the cytotoxic activity of TFX05-01 was inhibited when used in combination with a specific AKR1C3 inhibitor (IC50: 0.7 nM without inhibitor vs 188 nM with inhibitor in SNU-878 cells). TFX05-01 showed antitumor efficacy in AKR1C3 highly expressed HepG2 subcutaneously implanted xenograft model (TGI = 97% @2 mpk, QW, 3 doses IV). Concomitant PK studies showed that the concentration of active metabolites (TFX05-01A) in tumor was significantly higher (15~50 times) than that in plasma, which correlates with the selective release of the active DNA alkylating agent upon exposure to AKR1C3 in tumor tissues. Conclusion: TFX05-01 is a novel selective AKR1C3-activated prodrug, which is different from traditional non-selective alkylating agents for cancer therapy. Preclinical studies have shown profound in vivo efficacy of TFX05-01 in AKR1C3 overexpressed mouse tumor xenograft models without marked toxicity. TFX05-01 represents a novel treatment option for AKR1C3 expressing solid cancers. Preclinical GLP safety evaluations were promising and TFX05-01 was nominated for clinical trials. Citation Format: Charles Z Ding, Zhe Cai, Wei Sha. Preclinical evaluation of TFX05-01, a selective AKR1C3- targeted prodrug for solid tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5691.

New aldo-keto reductase 1C3 (AKR1C3) inhibitors based on the hydroxytriazole scaffold

The aldo-keto reductase 1C3 (AKR1C3) enzyme is considered an attractive target in Castration Resistant Prostate Cancer (CRPC) because of its role in the biosynthesis of androgens. Flufenamic acid, a non-selective AKR1C3 inhibitor, has previously been subjected to bioisosteric modulation to give rise to a series of compounds with the hydroxytriazole core. In this work, the hit compound of the previous series has been modulated further, and new, more potent, and selective derivatives have been obtained. The poor solubility of the most active compound (cpd 5) has been improved by substituting the triazole core with an isoxazole heteronucleous, with similar enzymatic activity being retained. Potent AKR1C3 inhibition is translated into antiproliferative effects against the 22RV1 CRPC cellular model, and the in-silico design, synthesis and biological activity of new compounds are described herein. Compounds have also been assayed in combination with two approved antitumor drugs, abiraterone and enzalutamide.

Knockdown of AKR1C3 Promoted Sorafenib Sensitivity Through Inhibiting the Phosphorylation of AKT in Hepatocellular Carcinoma.

BackgroundSorafenib, which can induce ferroptosis, is a multikinase inhibitor for enhancing survival in advanced hepatocellular carcinoma (HCC). However, a considerable challenge for the treatment of HCC is sorafenib resistance. Therefore, targeting the relationship between sorafenib resistance and ferroptosis genes may provide a novel approach for the treatment of HCC.Materials and MethodsWe analyzed the gene expression and clinicopathological factors from The Cancer Genome Atlas Liver Hepatocellular Carcinoma (TCGA-LIHC), International Cancer Genome Consortium (ICGC), and Gene Expression Omnibus (GEO) databases (GSE109211/GSE62813). The statistical analysis was conducted in R. Cell proliferation was assayed by MTT, cell colony-forming assay, and wound healing assay. Immunofluorescence assay and Western blot were used to evaluate the expression of AKT.ResultsMany ferroptosis-related genes were upregulated in the sorafenib-resistant group. Aldo-keto reductase 1C3 (AKR1C3) was highly expressed in sorafenib-resistant patients, and the high expression of AKR1C3 was associated with the poor prognosis of patients from the TCGA and ICGC databases. MTT and colony-forming assays showing AKR1C3 overexpression enhanced the proliferation of HCC cells and acute sorafenib resistance. Knockdown of AKR1C3 inhibited the proliferation of HCC cells and increased the drug sensitivity of sorafenib. Immunofluorescence assay and Western blot proved that AKR1C3 promoted the phosphorylation of AKT.ConclusionAKR1C3 can induce sorafenib resistance through promoting the phosphorylation of AKT in HCC. AKR1C3 inhibitors may be used in conjunction with sorafenib to become a better therapeutic target for HCC.

Study of Aldo-keto Reductase 1C3 Inhibitor with Novel Framework for Treating Leukaemia Based on Virtual Screening and In vitro Biological Activity Testing

Aldo-keto reductase 1C3(AKR1C3) is a potential target for the treatment of acute myeloid leukaemia and T-cell acute lymphoblastic leukaemia. In this study, pharmacophore models, molecular docking and virtual screening of target prediction were used to find a potential AKR1C3 inhibitor. Firstly, eight bacteriocin derivatives(Z1–Z8) were selected as training sets to construct 20 pharmacophore models. The best pharmacophore model MODEL_016 was obtained by Decoy test(the enrichment degree was 21.5117, and the fitting optimisation degree was 0.9668). Secondly, MODEL_016 was used for the virtual screening of ZINC database. Thirdly, the hit 83256 molecules were docked into the AKR1C3 protein. Compared to the total scores and interactions between compounds and protein, 16532 candidate compounds with higher docking scores and interactions with important residues PHE306 and TRP227 were screened. Lastly, eight compounds(A1–A8) that had good absorption, distribution, metabolism, excretion and toxicity(ADMET) properties were obtained by target prediction. Compounds A3 and A7 with high total score and good target prediction results were selected for in vitro biological activity test, whose IC50 values were 268.3 and 88.94 µmol/L, respectively. The results provide an important foundation for the discovery of novel AKR1C3 inhibitors. The research methods used in this study can also provide important references for the research and development of new drugs.

Design, Synthesis and Cytotoxicity Evaluation of Novel Indole Derivatives Containing Benzoic Acid Group as Potential AKR1C3 Inhibitors.

Castration-resistant prostate cancer (CRPC) is a fatal, metastatic form of prostate cancer, characterized by reactivation of the androgen axis. Aldo-keto reductase 1C3 (AKR1C3) converts androstenedione (AD) and 5α-androstanedione to testosterone (T) and 5α-dihydrotestosterone (DHT), respectively. In CRPC, AKR1C3 is upregulated and implicated in drug resistance and has been regarded as a potential therapeutic target. Here we examined a series of indole derivatives containing benzoic acid or phenylhydroxamic acid and found that 4-({3-[(3,4,5-trimethoxyphenyl)sulfanyl]-1H-indol-1-yl}methyl)benzoic acid (3e) and N-hydroxy-4-({3-[(3,4,5-trimethoxyphenyl)sulfanyl]-1H-indol-1-yl}methyl)benzamide (3q) inhibited 22Rv1 cell proliferation with IC50 values of 6.37 μM and 2.72 μM, respectively. In enzymatic assay, compounds 3e and 3q exhibited potent inhibitory effect against AKR1C3 (IC50 =0.26 and 2.39 μM, respectively). These results indicated that compounds 3e and 3q might be useful leads for further investigation of more potential AKR1C3 inhibitors used for CRPC.

Reversal of Apalutamide and Darolutamide Aldo-Keto Reductase 1C3-Mediated Resistance by a Small Molecule Inhibitor.

The antiandrogen therapeutics apalutamide and darolutamide entered the clinic in 2018 and 2019, respectively, for the treatment of castration-resistant prostate cancer (CRPC). Increased expression of the enzyme aldo-keto reductase 1C3 (AKR1C3) is phenotypic of CRPC. The enzyme acts to circumvent castration by producing potent androgens that drive proliferation. Furthermore, AKR1C3 mediates chemotherapeutic resistance to the standard of care, enzalutamide, a structural analogue of apalutamide. Resistance develops in almost all CRPC patients within three months of beginning treatment. Herein, we report that both apalutamide and the structurally distinct darolutamide induce AKR1C3 expression in in vitro models of prostate cancer and are susceptible to AKR1C3-mediated resistance. This effect is countered by pretreatment with a potent and highly selective AKR1C3 inhibitor, sensitizing high AKR1C3 expressing prostate cancer cell lines to the action of both chemotherapeutics with a concomitant reduction in expression of AKR1C3 and the biomarker prostate-specific antigen.

Potent and Highly Selective Aldo-Keto Reductase 1C3 (AKR1C3) Inhibitors Act as Chemotherapeutic Potentiators in Acute Myeloid Leukemia and T-Cell Acute Lymphoblastic Leukemia.

Aldo-keto reductase 1C3 (AKR1C3) catalyzes the synthesis of 9α,11β-prostaglandin (PG) F2α and PGF2α prostanoids that sustain the growth of myeloid precursors in the bone marrow. The enzyme is overexpressed in acute myeloid leukemia (AML) and T-cell acute lymphoblastic leukemia (T-ALL). Moreover, AKR1C3 confers chemotherapeutic resistance to the anthracyclines: first-line agents for the treatment of leukemias. The highly homologous isoforms AKR1C1 and AKR1C2 inactivate 5α-dihydrotestosterone, and their inhibition would be undesirable. We report herein the identification of AKR1C3 inhibitors that demonstrate exquisite isoform selectivity for AKR1C3 over the other closely related isoforms to the order of >2800-fold. Biological evaluation of our isoform-selective inhibitors revealed a high degree of synergistic drug action in combination with the clinical leukemia therapeutics daunorubicin and cytarabine in in vitro cellular models of AML and primary patient-derived T-ALL cells. Our developed compounds exhibited >100-fold dose reduction index that results in complete resensitization of a daunorubicin-resistant AML cell line to the chemotherapeutic and >100-fold dose reduction of cytarabine in both AML cell lines and primary T-ALL cells.

Bioisosteres of Indomethacin as Inhibitors of Aldo-Keto Reductase 1C3.

Aldo-keto reductase 1C3 (AKR1C3) is an attractive target in drug design for its role in resistance to anticancer therapy. Several nonsteroidal anti-inflammatory drugs such as indomethacin are known to inhibit AKR1C3 in a nonselective manner because of COX-off target effects. Here we designed two indomethacin analogues by proposing a bioisosteric connection between the indomethacin carboxylic acid function and either hydroxyfurazan or hydroxy triazole rings. Both compounds were found to target AKR1C3 in a selective manner. In particular, hydroxyfurazan derivative is highly selective for AKR1C3 over the 1C2 isoform (up to 90-times more) and inactive on COX enzymes. High-resolution crystal structure of its complex with AKR1C3 shed light onto the binding mode of the new inhibitors. In cell-based assays (on colorectal and prostate cancer cells), the two indomethacin analogues showed higher potency than indomethacin. Therefore, these two AKR1C3 inhibitors can be used to provide further insight into the role of AKR1C3 in cancer.

Potent and selective aldo-keto reductase 1C3 (AKR1C3) inhibitors based on the benzoisoxazole moiety: application of a bioisosteric scaffold hopping approach to flufenamic acid

The aldo-keto reductase 1C3 (AKR1C3) isoform plays a vital role in the biosynthesis of androgens and is considered an attractive target in prostate cancer (PCa). No AKR1C3-targeted agent has to date been approved for clinical use. Flufenamic acid and indomethacine are non-steroidal anti-inflammatory drugs known to inhibit AKR1C3 in a non-selective manner as COX off-target effects are also observed. Recently, we employed a scaffold hopping approach to design a new class of potent and selective AKR1C3 inhibitors based on a N-substituted hydroxylated triazole pharmacophore. Following a similar strategy, we designed a new series focused around an acidic hydroxybenzoisoxazole moiety, which was rationalised to mimic the benzoic acid role in the flufenamic scaffold. Through iterative rounds of drug design, synthesis and biological evaluation, several compounds were discovered to target AKR1C3 in a selective manner. The most promising compound of series (6) was found to be highly selective (up to 450-fold) for AKR1C3 over the 1C2 isoform with minimal COX1 and COX2 off-target effects. Other inhibitors were obtained modulating the best example of hydroxylated triazoles we previously presented. In cell-based assays, the most promising compounds of both series reduced the cell proliferation, prostate specific antigen (PSA) and testosterone production in AKR1C3-expressing 22RV1 prostate cancer cells and showed synergistic effect when assayed in combination with abiraterone and enzalutamide. Structure determination of AKR1C3 co-crystallized with one representative compound from each of the two series clearly identified both compounds in the androstenedione binding site, hence supporting the biochemical data.

Influence of Aldo-keto Reductase 1C3 in Prostate Cancer - A Mini Review.

Aldo-keto reductase 1C3 (AKR1C3) is an important oxidoreductase with multiple substrates, that are involved in producing extra-testicular androgens. Its activity is influenced by environmental exposures, as well as by genetic variants. These genetic variants could therefore produce variable testosterone levels and subsequent androgen receptor (AR) activation. This could lead to differential downstream production of the prostate-specific antigen (PSA). As PSA level is used for clinical evaluation of the prostate, these variations could impact prostate cancer (PC) diagnosis, as well as PC management outcomes. This review brings together information with regards to key functions of this enzyme, its relevance in PC, its transcriptional regulation, clinical aspects associated with genetics, differential regulation in cancer and cancer progression, and the types of AKR1C3 inhibitors with future therapeutic value. Based on these discussions, hypotheses are forwarded for future applicability of this enzyme and its genetic variants in transformational medical practices in PC. Options for the use of personalised AKR1C3 inhibitor drugs for late stage PC are also discussed.

AKR1C3 Inhibitory Potency of Naturally-occurring Amaryllidaceae Alkaloids of Different Structural Types

Aldo-keto reductase 103 (AKRIC3) is an important human enzyme that participates in the reduction of steroids and prostaglandins, which leads to proliferative signaling. AKRIC3 is frequently upregulated in various cancers, and this enzyme has been suggested as a therapeutic target for the treatment of these pathological conditions. The fact that the isoquinoline alkaloid stylopine has been identified as a potent AKRIC3 inhibitor has prompted us to screen a library of diverse types of Amaryllidaceae alkaloids, which biogenetically are isoquinoline alkaloids, on a recombinant form of AKRIC3. From the tested compounds, only tazettine showed moderate AKRIC3 inhibitory potency with an IC5o value of 15.8 ? 1.2 pM. Tazettine is a common Amaryllidaceac alkaloid, which could be used as a model substance for the further development of either analogues or related compounds with better inhibition potency.

Discovery of (R)-2-(6-Methoxynaphthalen-2-yl)butanoic Acid as a Potent and Selective Aldo-keto Reductase 1C3 Inhibitor.

Type 5 17β-hydroxysteroid dehydrogenase, aldo-keto reductase 1C3 (AKR1C3) converts Δ(4)-androstene-3,17-dione and 5α-androstane-3,17-dione to testosterone (T) and 5α-dihydrotestosterone, respectively, in castration resistant prostate cancer (CRPC). In CRPC, AKR1C3 is implicated in drug resistance, and enzalutamide drug resistance can be surmounted by indomethacin a potent inhibitor of AKR1C3. We examined a series of naproxen analogues and find that (R)-2-(6-methoxynaphthalen-2-yl)butanoic acid (in which the methyl group of R-naproxen was replaced by an ethyl group) acts as a potent AKR1C3 inhibitor that displays selectivity for AKR1C3 over other AKR1C enzymes. This compound was devoid of inhibitory activity on COX isozymes and blocked AKR1C3 mediated production of T and induction of PSA in LNCaP-AKR1C3 cells as a model of a CRPC cell line. R-Profens are substrate selective COX-2 inhibitors and block the oxygenation of endocannabinoids and in the context of advanced prostate cancer R-profens could inhibit intratumoral androgen synthesis and act as analgesics for metastatic disease.

Selective AKR1C3 Inhibitors Potentiate Chemotherapeutic Activity in Multiple Acute Myeloid Leukemia (AML) Cell Lines.

We report the design, synthesis, and evaluation of potent and selective inhibitors of aldo-keto reductase 1C3 (AKR1C3), an important enzyme in the regulatory pathway controlling proliferation, differentiation, and apoptosis in myeloid cells. Combination treatment with the nontoxic AKR1C3 inhibitors and etoposide or daunorubicin in acute myeloid leukemia cell lines, elicits a potent adjuvant effect, potentiating the cytotoxicity of etoposide by up to 6.25-fold and the cytotoxicity of daunorubicin by >10-fold. The results validate AKR1C3 inhibition as a common adjuvant target across multiple AML subtypes. These compounds in coadministration with chemotherapeutics in clinical use enhance therapeutic index and may avail chemotherapy as a treatment option to the pediatric and geriatric population currently unable to tolerate the side effects of cancer drug regimens.