Cytochrome P450 1B1 Inhibitor Research Articles

Inhibition of heme-thiolate monooxygenase CYP1B1 prevents hepatic stellate cell activation and liver fibrosis by accumulating trehalose.

Activation of extracellular matrix-producing hepatic stellate cells (HSCs) is a key event in liver fibrogenesis. We showed that the expression of the heme-thiolate monooxygenase cytochrome P450 1B1 (CYP1B1) was elevated in human and mouse fibrotic livers and activated HSCs. Systemic or HSC-specific ablation and pharmacological inhibition of CYP1B1 attenuated HSC activation and protected male but not female mice from thioacetamide (TAA)-, carbon tetrachloride (CCl4)-, or bile duct ligation (BDL)-induced liver fibrosis. Metabolomic analysis revealed an increase in the disaccharide trehalose in CYP1B1-deficient HSCs resulting from intestinal suppression of the trehalose-metabolizing enzyme trehalase, whose gene we found to be a target of RARα. Trehalose or its hydrolysis-resistant derivative lactotrehalose exhibited potent antifibrotic activity in vitro and in vivo by functioning as an HSC-specific autophagy inhibitor, which may account for the antifibrotic effect of CYP1B1 inhibition. Our study thus reveals an endobiotic function of CYP1B1 in liver fibrosis in males, mediated by liver-intestine cross-talk and trehalose. At the translational level, pharmacological inhibition of CYP1B1 or the use of trehalose/lactotrehalose may represent therapeutic strategies for liver fibrosis.

Development of novel N-aryl-2,4-bithiazole-2-amine-based CYP1B1 degraders for reversing drug resistance

Extrahepatic cytochrome P450 1B1 (CYP1B1), which is highly expressed in non-small cell lung cancer, is an attractive target for cancer prevention, therapy, and overcoming drug resistance. Historically, CYP1B1 inhibition has been the primary therapeutic approach for treating CYP1B1-related malignancies, but its success has been limited. This study introduced CYP1B1 degradation as an alternative strategy to counter drug resistance and metastasis in CYP1B1-overexpressing non-small cell lung cancer A549/Taxol cells via a PROTAC strategy. Our investigation revealed that the identification of the potent CYP1B1 degrader PV2, achieving DC50 values of 1.0 nM and inducing >90 % CYP1B1 degradation at concentrations as low as 10 nM in A549/Taxol cells. Importantly, PV2 enhanced the sensitivity of the A549/Taxol subline to Taxol, possibly due to its stronger inhibitory effects on P-gp through CYP1B1 degradation. Additionally, compared to the CYP1B1 inhibitor A1, PV2 effectively suppressed the migration and invasion of A549/Taxol cells by inhibiting the FAK/SRC and EMT pathways. These findings hold promise for a novel therapy targeting advanced CYP1B1+ non-small cell lung cancer.

Abstract LB296: Human CYP1B1 enhances cancer progression through induction of Sp1 via DNMT-mediated epigenetic regulation of miR-375

Abstract Human cytochrome P450 1B1 (CYP1B1) is a major catalytic enzyme for metabolism of 17β-estradiol (E2) to catechol estrogens, mainly carcinogenic metabolite 4-hydroxyestradiol (4-OHE2). To identify the unknown molecular mechanism for cancer progression induced by CYP1B1, we studied the role of CYP1B1 in human tumor cells, MCF-7, MDA-MB-231, and HeLa cells. Suppression of CYP1B1 by shRNA significantly reduced cancer cell viability and invasion. Clinical data from cancer patients showed that high level of CYP1B1 expression resulted in relatively lower survival rate. Interestingly, overexpression of CYP1B1 markedly activated Wnt/β-catenin signaling and EMT process, and suppression of specificity protein 1 (Sp1) by siRNA, an well-known transcription factor, demolished the promoting effects of CYP1B1 on cancer progression. To investigate the correlation between CYP1B1 and Sp1, we analyzed the clinical data from breast and cervical cancer patients and the results showed the positive correlation between two genes. Furthermore, TMS (tetramethoxystilbene), a specific CYP1B1 inhibitor, diminished the induction of Sp1 by CYP1B1, and 4-OHE2 exceedingly promoted the expression level of Sp1. Surprisingly, miR-375, known as an oncogenic microRNA, substantially decreased by 4-OHE2 and CYP1B1 overexpression in CYP1B1-transgenic (TG) mice. Methylation specific assay revealed that CYP1B1 suppressed miR-375 expression through induction of hyper-methylation on pre-miR-375. In addition, epigenetic regulation of miR-375 by CYP1B1 was executed via induction of DNA methyltransferases (DNMTs), DNMT1, 3a, and 3b. Enhanced expression level of Sp1 by 4-OHE2 was significantly deteriorated by 5-aza-dC, a DNMT inhibitor. Taken together, our data suggest that CYP1B1 enhances cancer progression through induction of cancer cell proliferation and invasion via DNMT-mediated epigenetic regulation of miR-375 and further promotion of Sp1 expression. Citation Format: Young-Jin Chun, Yeo-Jung Kwon, Tae-Uk Kwon. Human CYP1B1 enhances cancer progression through induction of Sp1 via DNMT-mediated epigenetic regulation of miR-375 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB296.

Design of Novel 2-Phenylquinazolin-4-amines as Selective CYP1B1 Inhibitors for Overcoming Paclitaxel Resistance in A549 Cells.

Cytochrome P450 1B1 (CYP1B1) contributes to the metabolic inactivation of chemotherapeutics when overexpressed in tumor cells. Selective inhibition of CYP1B1 holds promise for reversing drug resistance. In our pursuit of potent CYP1B1 inhibitors, we designed and synthesized a series of 2-phenylquinazolin-4-amines. A substantial proportion of these newly developed inhibitors demonstrated inhibitory activity against CYP1B1, accompanied by improved water solubility. Remarkably, compound 14b exhibited exceptional inhibitory efficacy and selectivity toward CYP1B1. Molecular docking studies suggested that the expansion of the π-system through aromatization, the introduction of an amine group, and iodine atom augmented the binding affinity. Furthermore, inhibitors 14a, 14b, and 14e demonstrated the ability to significantly reduce the resistance in A549 cells to paclitaxel, while also inhibiting the migration and invasion of these cells. Finally, radioiodine labeling experiments shed light on the metabolic pathway of compound 5l in mice, highlighting the potential of 125I-5l as a radioactive probe for future research endeavors.

A new class of CYP1B1 inhibitors derived from bentranil

Cytochrome P450 1B1 (CYP1B1) is highly expressed in a variety of tumors and implicated to drug resistance. More and more researches have suggested that CYP1B1 is a new target for cancer prevention and therapy. Various CYP1B1 inhibitors with a rigid polycyclic skeleton have been developed, such as flavonoids, trans-stilbenes, and quinazolines. To obtain a new class of CYP1B1 inhibitors, we designed and synthesized a series of bentranil analogues, moreover, IC50 determinations were performed for CYP1B1 inhibition of five of these compounds and found that 6o and 6q were the best inhibitors, with IC50 values in the nM range. The selectivity index (SI) of CYP1B1 over CYP1A1 and CYP1A2 was 30-fold higher than that of α-naphthoflavone (ANF). The molecular docking results showed that compound 6q fitted better into the CYP1B1 binding site than other compounds, which was consistent with our experimental results. On the basis of 6o and 6q, it is expected to develop CYP1B1 inhibitors with stronger affinity, higher selectivity and better solubility.

Design of Cytochrome P450 1B1 Inhibitors via a Scaffold-Hopping Approach.

Cytochrome P450 1B1 (CYP1B1) is a potential drug target in cancer research that is overexpressed in several solid tumors but is present only at low levels in healthy tissues. Its expression is associated with resistance to common chemotherapeutics, while inhibitors restore efficacy to these drugs in model systems. The majority of CYP1B1 inhibitors are derived from a limited number of scaffolds, and few have achieved outstanding selectivity against other human CYPs, which could impede clinical development. This study explores a new chemical space for CYP1B1 inhibitors using a scaffold-hopping approach and establishes 2,4-diarylthiazoles as a promising framework for further development. From a small library, compound 15 emerged as the lead, with picomolar CYP1B1 inhibition, and over 19,000-fold selectivity against its relative, CYP1A1. To investigate the activity of 15, molecular dynamics, optical spectroscopy, point mutations, and traditional structure-activity relationships were employed and revealed key interactions important for the development of CYP1B1 inhibitors.

In silico guided designing of optimized benzochalcones derivatives as potent CYP1B1 inhibitors: An integrated in vitro and ONIOM study

Cytochrome P4501B1 (CYP1B1) is reported to be overexpressed in various malignancies including ovarian, lung, lymph, and breast cancers. The overexpression of this enzyme is accountable for the biotransformation-based inactivation of some anti-cancer drugs i.e. Docetaxel, Paclitaxel, and Cisplatin. To circumvent solutions to this issue, the current study reports some optimized derivatives of benzochalcone as selective CYP1B1 inhibitors. The optimized derivatives were screened using some structure-based drug-designing approaches including molecular docking and molecular dynamics. The implemented approaches revealed that all the designed molecules demonstrated not only essential interactions with key amino acid residues but also maintained stability within the active site of CYP1B1. Furthermore, to validate the in-silico results and develop a SAR, the designed molecules were subsequently synthesized and tested for their ability to selectively inhibit CYP1B1 over CYP1A1 using well established EROD assay. This assay results suggested that compounds 1(c), 1(d), and 1(e) are eightfold more selective CYP1B1 inhibitors over CYP1A1 with IC50 values ranging from 0.06 to 0.09 μM respectively. Among these, compound 1(d) manifested potent inhibitory activity i.e. IC50 of 0.06 μM with 24 folds selectivity over 1A1. To have a better insight into the binding pattern of 1(d) within CYP1B1 and precisely compute binding affinity for 1(d)-CYP1B1 complex, one of the advanced QM/MM approaches i.e. ONIOM has been implemented. Where 1(d)-CYP1B1 complex conferred comparable binding affinity in terms of ΔG (kcal/mol) with that of ANF-CYP1B1 complex. This research could provide a suitable starting point for the development of more potent multi-functional compounds with CYP1B1 inhibitory activity.

Induction of synergistic apoptosis by tetramethoxystilbene and nutlin-3a in human cervical cancer cells.

2,4,3',5'-Tetramethoxystilbene (TMS) is a selective inhibitor of cytochrome P450 1B1 to block the conversion from estradiol to 4-OH-estradiol. Several studies suggested that TMS may act as a potent anti-cancer agent for hormone-related cancer including cervical cancer. Nutlin-3a is a cis-imidazoline analog that interferes with the interaction between mouse double minute 2 homolog (MDM2) and the tumor suppressor p53. The purpose of the study was to compare the cytotoxic effect of TMS and nutlin-3a treatment individually and in combination in HeLa cells. To assess the potential synergistic effects between TMS and nutlin-3a, low concentrations of TMS and nutlin-3a were simultaneously treated in HeLa cells. Based on cell viability, apoptosis assays, and the increase in cleaved caspase-3 and poly (ADP-ribose) polymerase cleavage, it was demonstrated that the combination with TMS and nutlin-3a exerts a synergistic effect on cancer cell death. Isobologram analysis of HeLa cells noted synergism between TMS and nutlin-3a. The combined treatment increased the expression of mitochondrial pro-apoptotic factors such as Bax and Bak, and decreased the expression of the XIAP. In addition, combination treatment significantly enhanced the translocation of AIF to the nucleus in HeLa cells. In conclusion, the results demonstrate that the combination of TMS and nutlin-3a induces synergistic apoptosis in HeLa cells, suggesting the possibility that this combination can be applied as a novel therapeutic strategy for cervical cancer.

CYP1B1 Augments the Mesenchymal, Claudin-Low, and Chemoresistant Phenotypes of Triple-Negative Breast Cancer Cells.

Cytochrome P4501B1 (CYP1B1) is elevated in breast cancer. Studies indicate a relationship between CYP1B1 and aggressive cancer phenotypes. Here, we report on in vitro studies in triple-negative breast cancer cell lines, where knockdown (KD) of CYP1B1 was used to determine the influence of its expression on invasive cell phenotypes. CYP1B1 KD in MDA-MB-231 cells resulted in the loss of mesenchymal morphology, altered expression of epithelial–mesenchymal genes, and increased claudin (CLDN) RNA and protein. CYP1B1 KD cells had increased cell-to-cell contact and paracellular barrier function, a reduced rate of cell proliferation, abrogation of migratory and invasive activity, and diminished spheroid formation. Analysis of clinical breast cancer tumor samples revealed an association between tumors exhibiting higher CYP1B1 RNA levels and diminished overall and disease-free survival. Tumor expression of CYP1B1 was inversely associated with CLDN7 expression, and CYP1B1HI/CLDN7LOW identified patients with lower median survival. Cells with CYP1B1 KD had an enhanced chemosensitivity to paclitaxel, 5-fluorouracil, and cisplatin. Our findings that CYP1B1 KD can increase chemosensitivity points to therapeutic targeting of this enzyme. CYP1B1 inhibitors in combination with chemotherapeutic drugs may provide a novel targeted and effective approach to adjuvant or neoadjuvant therapy against certain forms of highly metastatic breast cancer.

Ameliorative Role of Fluconazole Against Abdominal Aortic Constriction-Induced Cardiac Hypertrophy in Rats.

Cytochrome P450 1B1 (CYP1B1) is known to be involved in the pathogenesis of several cardiovascular diseases, including cardiac hypertrophy and heart failure, through the formation of cardiotoxic metabolites named as mid-chain hydroxyeicosatetraenoic acids (HETEs). Recently, we have demonstrated that fluconazole decreases the level of mid-chain HETEs in human liver microsomes, inhibits human recombinant CYP1B1 activity, and protects against angiotensin II-induced cellular hypertrophy in H9c2 cells. Therefore, the overall purpose of this study was to elucidate the potential cardioprotective effect of fluconazole against cardiac hypertrophy induced by abdominal aortic constriction (AAC) in rats. Male Sprague-Dawley rats were randomly assigned into 4 groups such as sham control rats, fluconazole-treated (20 mg/kg daily for 4 weeks, intraperitoneal) sham rats, AAC rats, and fluconazole-treated (20 mg/kg) AAC rats. Baseline and 5 weeks post-AAC echocardiography were performed. Gene and protein expressions were measured using real-time PCR and Western blot analysis, respectively. The level of mid-chain HETEs was determined using liquid chromatography-mass spectrometry. Echocardiography results showed that fluconazole significantly prevented AAC-induced left ventricular hypertrophy because it ameliorated the AAC-mediated increase in left ventricular mass and wall measurements. In addition, fluconazole significantly prevented the AAC-mediated increase of hypertrophic markers. The antihypertrophic effect of fluconazole was associated with a significant inhibition of CYP1B1, CYP2C23, and 12-LOX and a reduction in the formation rate of mid-chain HETEs. This study demonstrates that fluconazole protects against left ventricular hypertrophy, and it highlights the potential repurposing of fluconazole as a mid-chain HETEs forming enzymes' inhibitor for the protection against cardiac hypertrophy.

Unraveling the Structure-Dependent Inhibitory Effects of Ginsenoside Series Compounds on Human Cytochrome P450 1B1.

Cytochrome P450 1B1(CYP1B1) is an extrahepatic P450 isoenzyme that can participate in processes of undermining the effectiveness and safety of anti-cancer therapy. Ginsenosides are the main active ingredients in ginseng, which possesses rich pharmacological activities, including anti-cancer activity and organ protection. However, the effect of ginsenosides on the activity of CYP1B1 remains unclear. The present study aimed to investigate the inhibitory effect of ginsenosides on CYP1B1 and reveal the structure-inhibitory activity relationship. Firstly, recombinant CYP1B1 and EROD reactions were used to evaluate the inhibitory effect of ginsenosides. Secondly, molecular docking was used to simulate the interactions between ginsenosides and CYP1B1. Finally, the structure-inhibitory activity relationship was analyzed. The ginsenosides, Rb2, Rd, and Rg3, significantly inhibited CYP1B1; the ginsenoside Rd showed the strongest inhibition effect, with a Ki value of 47.37 μM in non-competitive mode. Notably, ginsenoside Rd formed hydrogen bonds with two key amino acid residues of CYP1B1, and one bond was between the glycosyl in position 20 and ALA330, which also made ginsenoside Rd close to the heme iron of CYP1B1. In contrast, ginsenosides, Rb2 and Rg3, which showed weaker inhibition, interacted with only one CYP1B1 residue by the hydrogen bond, which was far away from the heme iron. Finally, the structure-inhibitory activity relationship analysis demonstrated that the number of glycosyls in position 20 and the type of sapogenins in the ginsenoside structure are the key factors determining inhibitory activity. Meanwhile, ALA330 was a vital amino acid in the potent inhibition of CYP1B1 by ginsenosides. A structure-dependent inhibitory effect on CYP1B1 was revealed for ginsenosides, among which ginsenoside Rd showed the strongest inhibition due to its mono-glycosyl in position 20 of the ginsenoside parent structure. These findings would provide evidence for the synthesis of novel CYP1B1 inhibitors to augment the anti-cancer therapeutic effect.

Possible Role of Cytochrome P450 1B1 in the Mechanism of Gemcitabine Resistance in Pancreatic Cancer.

Patient-derived xenograft models reportedly represent original tumor morphology and gene mutation profiles. In addition, patient-derived xenografts are expected to recapitulate the parental tumor drug responses. In this study, we analyzed the pathways involved in gemcitabine resistance using patient-derived xenograft models of pancreatic cancer. The patient-derived xenograft models were established using samples from patients with pancreatic cancer. The models were treated with gemcitabine to better understand the mechanism of resistance to this anti-cancer drug. We performed comparative gene analysis through the next-generation sequencing of tumor tissues from gemcitabine-treated or non-treated patient-derived xenograft mice and gene set enrichment analysis to analyze mRNA profiling data. Pathway analysis of gemcitabine-treated patient-derived xenografts disclosed the upregulation of multiple gene sets and identified several specific gene pathways that could potentially be related to gemcitabine resistance in pancreatic cancer. Further, we conducted an in vitro analysis to validate these results. The mRNA expression of cytochrome P450 1B1 and cytochrome P450 2A6 was upregulated in a concentration-dependent manner following gemcitabine treatment. Moreover, the sensitivity to gemcitabine increased, and viable cells were decreased by the cytochrome P450 1B1 inhibitor, indicating that the cytochrome P450 1B1 pathway may be related to gemcitabine resistance in pancreatic cancer.

New Perspectives of CYP1B1 Inhibitors in the Light of Molecular Studies

Human cytochrome P450 1B1 (CYP1B1) is an extrahepatic heme-containing monooxygenase. CYP1B1 contributes to the oxidative metabolism of xenobiotics, drugs, and endogenous substrates like melatonin, fatty acids, steroid hormones, and retinoids, which are involved in diverse critical cellular functions. CYP1B1 plays an important role in the pathogenesis of cardiovascular diseases, hormone-related cancers and is responsible for anti-cancer drug resistance. Inhibition of CYP1B1 activity is considered as an approach in cancer chemoprevention and cancer chemotherapy. CYP1B1 can activate anti-cancer prodrugs in tumor cells which display overexpression of CYP1B1 in comparison to normal cells. CYP1B1 involvement in carcinogenesis and cancer progression encourages investigation of CYP1B1 interactions with its ligands: substrates and inhibitors. Computational methods, with a simulation of molecular dynamics (MD), allow the observation of molecular interactions at the binding site of CYP1B1, which are essential in relation to the enzyme’s functions.

Inhibition of Cytochrome P450 1B1 Prevents Hepatic Stellate Cell Activation and Liver Fibrosis

Background : Liver fibrosis often results from chronic liver injury and it is characterized by the accumulation of extracellular matrix. Activation of the hepatic stellate cell (HSC) is a key fibrogenic event. Cytochrome P450 1b1 (Cyp1b1) is a heme-thiolate monooxygenase involved in the metabolism of endogenous compounds and xenobiotics. The goal of this study is to determine whether and how Cyp1b1 plays a role in hepatic stellate cell (HSC) activation and liver fibrosis. Methods : The effects of Cyp1b1 on HSC activation and fibrogenesis were assessed by real-time PCR, immunofluorescence, and RNA-seq analysis. Wild-type (WT) and Cyp1b1 knockout (Cyp1b1-/-) mice were subjected to thioacetamide (TAA), carbon tetrachloride (CCl4), or bile duct ligation (BDL) models of liver fibrosis, and the fibrosis phenotypes were analyzed at the histology and gene expression levels. Hepatic retinoid levels were measured by liquid chromatography-mass spectrometry (LC-MS/MS). Results : Cyp1b1 is highly expressed in HSCs. The expression of Cyp1b1 was elevated in fibrotic mouse and human livers, as well as in activated mouse and human HSCs. In contrast, down-regulation or pharmacological inhibition of Cyp1b1 by 2,4,3′,5′-tetramethoxystilbene (TMS) attenuated HSC activation in vitro and in vivo. Cyp1b1-/- mice or WT mice treated with TMS were protected from liver fibrosis. Mechanistically, the fibrogenic induction of Cyp1b1 is likely mediated by the transcriptional factor wilms' tumor 1 (WT1). The pro-fibrogenic activity of Cyp1b1 may have been accounted for by its metabolism of retinoids in HSCs. Conclusion : Our study has uncovered an important endobiotic function of Cyp1b1 in promoting liver fibrosis. Cyp1b1 promotes HSC activation and liver fibrogenesis by facilitating retinoids depletion. Pharmacological inhibition of Cyp1b1 might be a potential strategy for the treatment of liver fibrosis.

Fluconazole Protects against Abdominal Aortic Constriction‐Induced Cardiac Hypertrophy

Purpose: Cytochrome P450 1B1 (CYP1B1) is known to be involved in the pathogenesis of several cardiovascular diseases such as cardiac hypertrophy and heart failure, through the formation of cardiotoxic metabolites named as midchain hydroxyeicosatetraenoic acids (HETEs). Recently, we have demonstrated that fluconazole, an antifungal agent, decreases the level of mid-chain HETEs in human liver microsomes, inhibits human recombinant CYP1B1 activity and protects against angiotensin II-induced cellular hypertrophy in H9c2 cells. Therefore, the overall objectives of the present study were to elucidate the potential cardioprotective effect of fluconazole against cardiac hypertrophy induced by abdominal aortic constriction (AAC) and unravel the mechanism(s) involved. Methods: Male Sprague-Dawley rats were randomly assigned into four groups; sham control rats, fluconazole-treated (20 mg/kg daily for 4 weeks, intraperitoneal) sham rats, AAC rats and fluconazole-treated (20 mg/kg) AAC rats. Baseline and 5 weeks post-AAC echocardiography were performed. Gene and protein expression were measured using real-time PCR and Western blot analysis, respectively. The level of mid-chain HETEs was determined using liquid chromatography–mass spectrometry (LC/MS). Results: Echocardiography results showed that fluconazole significantly reversed the AAC-induced left ventricular hypertrophy, as it was able to ameliorate the AAC-mediated increase in left ventricular mass and several wall measurements. In addition, fluconazole significantly prevented the AAC-mediated increase of hypertrophic markers, β-myosin heavy chain (MHC)/α-MHC and atrial natriuretic peptide (ANP). The antihypertrophic effect of fluconazole was associated with a significant inhibition of CYP1B1 at the gene and protein levels as well as a reduction in the formation rate of midchain HETEs. Conclusion: The current study demonstrates a strong evidence that fluconazole protects against left ventricular hypertrophy. The findings of the present work highlight the potential repurposing of fluconazole as a CYP1B1 inhibitor for the protection against cardiac hypertrophy and a possible treatment for heart failure.

Discovery of heterocycle-containing α-naphthoflavone derivatives as water-soluble, highly potent and selective CYP1B1 inhibitors

Cytochrome P450 1B1 (CYP1B1) has been well validated as an attractive target for cancer prevention and drug resistance reversal. In continuation of our interest in this area, herein, a set of forty-six 6,7,10-trimethoxy-α-naphthoflavone derivatives varying in B ring was synthesized and screened against CYP1 enzymes, leading to the identification of fluorine-containing compound 15i as the most potent and selective CYP1B1 inhibitor (IC50 value of 0.07nM), being 84-fold more potent than that of the template molecule ANF. Alternatively, the amino-substituted derivative 13h not only possessed a potent inhibitory effect on CYP1B1 (IC50 value of 0.98nM), but also had a substantially increased water solubility as compared with the lead ANF (311μg/mL for 13h and <5μg/mL for ANF). The current study expanded the structural diversity of CYP1B1 inhibitors, and compound 13h could be considered as a promising starting point with great potential for further studies.

Resveratrol attenuates angiotensin II-induced cellular hypertrophy through the inhibition of CYP1B1 and the cardiotoxic mid-chain HETE metabolites.

Several reports demonstrated the direct contribution of cytochrome P450 1B1 (CYP1B1) enzyme and its associated cardiotoxic mid-chain, hydroxyeicosatetraenoic acid (HETEs) metabolites in the development of cardiac hypertrophy. Resveratrol is commercially available polyphenol that exerts beneficial effects in wide array of cardiovascular diseases including cardiac hypertrophy, myocardial infarction and heart failure. Nevertheless, the underlying mechanisms responsible for these effects are not fully elucidated. Since resveratrol is a well-known CYP1B1 inhibitor, the purpose of this study is to test whether resveratrol attenuates angiotensin II (Ang II)-induced cellular hypertrophy through inhibition of CYP1B1/mid-chain HETEs mechanism. RL-14 and H9c2 cells were treated with vehicle or 10 μM Ang II in the absence and presence of 2, 10 or 50 μM resveratrol for 24 h. Thereafter, the level of mid-chain HETEs was determined using liquid chromatography–mass spectrometry (LC/MS). Hypertrophic markers and CYP1B1 gene expression and protein levels were measured using real-time PCR and Western blot analysis, respectively. Our results demonstrated that resveratrol, at concentrations of 10 and 50 μM, was able to attenuate Ang-II-induced cellular hypertrophy as evidenced by substantial inhibition of hypertrophic markers, β-myosin heavy chain (MHC)/α-MHC and atrial natriuretic peptide. Ang II significantly induced the protein expression of CYP1B1 and increased the metabolite formation rate of its associated mid-chain HETEs. Interestingly, the protective effect of resveratrol was associated with a significant decrease of CYP1B1 protein expression and mid-chain HETEs. Our results provided the first evidence that resveratrol protects against Ang II-induced cellular hypertrophy, at least in part, through CYP1B1/mid-chain HETEs-dependent mechanism.

19‐(S/R)Hydroxyeicosatetraenoic Acid is a Novel Endogenous Inhibitor of Cytochrome P450 1B1 in Enantioselective Manner

PurposeCYP1B1 is known to contribute to the pathogenesis of several diseases such as cancer and cardiac hypertrophy by forming the toxic metabolites. We recently reported that the arachidonic acid metabolite, 19(S/R)hydroxyeicosatetraenoic (HETE) acid, confers cardioprotection against cardiac hypertrophy by inhibiting the formation of cardiotoxic metabolites, midchain HETEs, known to be formed by CYP1B1. This raised the question whether 19(S/R)‐HETE can directly inhibit the CYP1B1.MethodsHuman ventricular cardiomyocytes, RL‐14 cells were treated with vehicle or 10 μM Ang II in the absence and presence of 20 μM 19(R)‐HETE or 19(S)‐HETE for 24 h. Gene and protein expression were measured using real‐time PCR and Western blot analysis, respectively. The level of mid‐chain HETEs was determined using liquid chromatography–mass spectrometry (LC/MS). The O‐dealkylation rate of 7‐ethoxyresorufin (EROD) by recombinant human CYP1B1 was measured in the absence and presence of 19(R)‐HETE or 19(S)‐HETE.ResultsThe results showed that both 19(R)‐HETE and 19(S)‐HETE significantly decreased the metabolite formation rate of midchain HETEs, namely 8‐, 9‐, 12‐ and 15‐HETE compared to control group. Nonlinear regression analysis and comparisons showed that the mode of inhibition for 19(R)‐HETE and 19(S)‐HETE is non‐competitive inhibition of CYP1B1 enzyme. Dixon plots showed that 19(R)‐HETE and 19(S)‐HETE have Ki values of 89.1 and 37.3 nM, respectively. The Ki values of both enantiomers showed that the S‐enantiomer is more potent than the R‐enantiomer by approximately 2.4 fold.ConclusionThe current study suggests that 19(R)‐HETE and 19(S)‐HETE could be considered a novel therapeutic modality in the treatment of cardiac hypertrophy, and cancer. Moreover, given that a non‐competitive inhibitor might bind to the enzyme regulatory region, 19(R)‐HETE and 19(S)‐HETE could be the focus for unraveling the obscure mechanisms of CYP1B1 enzymatic reaction.Support or Funding InformationThis work was supported by a grant from CIHR to A.O.S.E. S.M.S. is the recipient of Alberta Innovates Graduate Student Scholarship.

Carvedilol serves as a novel CYP1B1 inhibitor, a systematic drug repurposing approach through structure-based virtual screening and experimental verification

Cytochrome P450 1B1 (CYP1B1) is a promising target for prevention and therapy of cancer, particularly those with drug resistance, stimulating cancer cell survival, and promoting cancer resistance. In view of the extreme complexity and high risk in drug discovery and development, a drug repurposing strategy was applied in the present study to find potential CYP1B1 inhibitors through structure-based virtual screening in the FDA database. Intriguingly, after a thorough assessment of docking scores, binding affinities, as well as binding modes, six compounds were highlighted for further verification. In fact, both carvedilol and indacaterol showed inhibitory activity towards human CYP1B1 with the IC50 of 1.11 μM and 59.52 μM, respectively, according to EROD assay; however, neither docking score nor the detailed binding mode of carvedilol in the hit pose dictated to be a superior CYP1B1 inhibitor to indacaterol, which called for the necessity to re-access the binding mode of carvedilol. Thus, the top two representative docking poses of carvedilol were re-assessed. Indeed, compared to the one hit in the virtual screening (due to a false positive Glide gscore), the other docking pose exhibited ideal performance in both molecular dynamics (MD) simulation, binding free energy, and density functional theory (DFT) calculation evaluations. This identification of the exact binding pose of carvedilol is not only essential for a better understanding of the mechanism underlying its activity, but also contributes to uncovering the structure-activity relationship of CYP1B1 inhibitors. Of note, carvedilol exhibited direct cytotoxicity against both human lung adenocarcinoma epithelial cell line A459 and its Taxol-resistant subline (A549/Taxol). In particular, it showed superior toxicity towards A549/Taxol cells that overexpressed CYP1B1, which further supported its potential to be an effective CYP1B1 inhibitor.

Synthesis and structure-activity relationship studies of α-naphthoflavone derivatives as CYP1B1 inhibitors

Cytochrome P450 1B1(CYP1B1) has been recognized as an important target for cancer prevention and drug resistance reversal. In order to obtain potent and selective CYP1B1 inhibitors, a series of forty-one α-naphthoflavone (ANF) derivatives were synthesized, characterized, and evaluated for CYP1B1, CYP1A1 and CYP1A2 inhibitory activities. A closure look into the structure-activity relationship for the inhibitory effects on CYP1B1 indicated that modification of the C ring of ANF would decrease the CYP1B1 inhibitory potency, while incorporation of substituent(s) into the different positions of the B ring yielded analogues with varying CYP1B1 inhibitory capacity. Among these derivatives, compounds 9e and 9j were identified as the most potent two selective CYP1B1 inhibitors with IC50 values of 0.49 and 0.52 nM, respectively, which were 10-fold more potent than the lead compound ANF. In addition, molecular docking and a reasonable 3D-QSAR (three-dimensional quantitative structure-activity relationship) study were performed to provide a better understanding of the key structural features influencing the CYP1B1 inhibitory activity. The results achieved in this study would lay a foundation for future development of selective, potent, low-toxic and water-soluble CYP1B1 inhibitors.