Sorafenib has soluble epoxide hydrolase inhibitory activity, which contributes to its effect profile in vivo

Pathological and pharmacological functions of the metabolites of polyunsaturated fatty acids mediated by cyclooxygenases, lipoxygenases, and cytochrome P450s in cancers

Oxylipins have garnered increasing attention because they were consistently shown to play pathological and/or pharmacological roles in the development of multiple cancers. Oxylipins are the metabolites of polyunsaturated fatty acids via both enzymatic and nonenzymatic pathways. The enzymes mediating the metabolism of PUFAs include but not limited to lipoxygenases (LOXs), cyclooxygenases (COXs), and cytochrome P450s (CYPs) pathways, as well as the down-stream enzymes. Here, we systematically summarized the pleiotropic effects of oxylipins in different cancers through pathological and pharmacological aspects, with specific reference to the enzyme-mediated oxylipins. We discussed the specific roles of oxylipins on cancer onset, growth, invasion, and metastasis, as well as the expression changes in the associated metabolic enzymes and the associated underlying mechanisms. In addition, we also discussed the clinical application and potential of oxylipins and related metabolic enzymes as the targets for cancer prevention and treatment. We found the specific function of most oxylipins in cancers, especially the underlying mechanisms and clinic applications, deserves and needs further investigation. We believe that research on oxylipins will provide not only more therapeutic targets for various cancers but also dietary guidance for both cancer patients and healthy humans.

1,3-Dichloroadamantyl-Containing Ureas as Potential Triple Inhibitors of Soluble Epoxide Hydrolase, p38 MAPK and c-Raf

Soluble epoxide hydrolase (sEH) is an enzyme involved in the metabolism of bioactive lipid signaling molecules. sEH converts epoxyeicosatrienoic acids (EET) to virtually inactive dihydroxyeicosatrienoic acids (DHET). The first acids are "medicinal" molecules, the second increase the inflammatory infiltration of cells. Mitogen-activated protein kinases (p38 MAPKs) are key protein kinases involved in the production of inflammatory mediators, including tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). p38 MAPK signaling plays an important role in the regulation of cellular processes, especially inflammation. The proto-oncogenic serine/threonine protein kinase Raf (c-Raf) is a major component of the mitogen-activated protein kinase (MAPK) pathway: ERK1/2 signaling. Normal cellular Raf genes can also mutate and become oncogenes, overloading the activity of MEK1/2 and ERK1/2. The development of multitarget inhibitors is a promising strategy for the treatment of socially dangerous diseases. We synthesized 1,3-disubstituted ureas and diureas containing a dichloroadamantyl moiety. The results of computational methods show that soluble epoxide hydrolase inhibitors can act on two more targets in different signaling pathways of mitogen-activated protein kinases p38 MAPK and c-Raf. The two chlorine atoms in the adamantyl moiety may provide additional Cl-π interactions in the active site of human sEH. Molecular dynamics studies have shown that the stability of ligand-protein complexes largely depends on the "spacer effect." The compound containing a bridge between the chloroadamantyl fragment and the ureide group forms more stable ligand-protein complexes with sEH and p38 MAPK, which indicates a better conformational ability of the molecule in the active sites of these targets. In turn, a compound containing two chlorine atoms forms a more stable complex with c-Raf, probably due to the presence of additional halogen bonds of chlorine atoms with amino acid residues.

Chemoproteomics Reveals the Pan-HER Kinase Inhibitor Neratinib To Target an Arabidopsis Epoxide Hydrolase Related to Phytohormone Signaling

Plant phytohormone pathways are regulated by an intricate network of signaling components and modulators, many of which still remain unknown. Here, we report a forward chemical genetics approach for the identification of functional SA agonists in Arabidopsis thaliana that revealed Neratinib (Ner), a covalent pan-HER kinase inhibitor drug in humans, as a modulator of SA signaling. Instead of a protein kinase, chemoproteomics unveiled that Ner covalently modifies a surface-exposed cysteine residue of Arabidopsis epoxide hydrolase isoform 7 (AtEH7), thereby triggering its allosteric inhibition. Physiologically, the Ner application induces jasmonate metabolism in an AtEH7-dependent manner as an early response. In addition, it modulates PATHOGENESIS RELATED 1 (PR1) expression as a hallmark of SA signaling activation as a later effect. AtEH7, however, is not the exclusive target for this physiological readout induced by Ner. Although the underlying molecular mechanisms of AtEH7-dependent modulation of jasmonate signaling and Ner-induced PR1-dependent activation of SA signaling and thus defense response regulation remain unknown, our present work illustrates the powerful combination of forward chemical genetics and chemical proteomics for identifying novel phytohormone signaling modulatory factors. It also suggests that marginally explored metabolic enzymes such as epoxide hydrolases may have further physiological roles in modulating signaling.

Sorafenib increases cytochrome P450 lipid metabolites in patient with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer death, and medical treatment options are limited. The multikinase inhibitor sorafenib was the first approved drug widely used for systemic therapy in advanced HCC. Sorafenib might affect polyunsaturated fatty acids (PUFA)-derived epoxygenated metabolite levels, as it is also a potent inhibitor of the soluble epoxide hydrolase (sEH), which catalyzes the conversion of cytochrome-P450 (CYP)-derived epoxide metabolites derived from PUFA, such as omega-6 arachidonic acid (AA) and omega-3 docosahexaenoic acid (DHA), into their corresponding dihydroxy metabolites. Experimental studies with AA-derived epoxyeicosatrienoic acids (EETs) have shown that they can promote tumor growth and metastasis, while DHA-derived 19,20-epoxydocosapentaenoic acid (19,20-EDP) was shown to have anti-tumor activity in mice. In this study, we found a significant increase in EET levels in 43 HCC patients treated with sorafenib and a trend towards increased levels of DHA-derived 19,20-EDP. We demonstrate that the effect of sorafenib on CYP- metabolites led to an increase of 19,20-EDP and its dihydroxy metabolite, whereas DHA plasma levels decreased under sorafenib treatment. These data indicate that specific supplementation with DHA could be used to increase levels of the epoxy compound 19,20-EDP with potential anti-tumor activity in HCC patients receiving sorafenib therapy.

Stress Granules in the Anti-Cancer Medications Mechanism of Action: A Systematic Scoping Review

Stress granule (SG) formation is a well-known cellular mechanism for minimizing stress-related damage and increasing cell survival. In addition to playing a critical role in the stress response, SGs have emerged as critical mediators in human health. It seems logical that SGs play a key role in cancer cell formation, development, and metastasis. Recent studies have shown that many SG components contribute to the anti-cancer medications' responses through tumor-associated signaling pathways and other mechanisms. SG proteins are known for their involvement in the translation process, control of mRNA stability, and capacity to function in both the cytoplasm and nucleus. The current systematic review aimed to include all research on the impact of SGs on the mechanism of action of anti-cancer medications and was conducted using a six-stage methodological framework and the PRISMA guideline. Prior to October 2021, a systematic search of seven databases for eligible articles was performed. Following the review of the publications, the collected data were subjected to quantitative and qualitative analysis. Notably, Bortezomib, Sorafenib, Oxaliplatin, 5-fluorouracil, Cisplatin, and Doxorubicin accounted for the majority of the medications examined in the studies. Overall, this systematic scoping review attempts to demonstrate and give a complete overview of the function of SGs in the mechanism of action of anti-cancer medications by evaluating all research.

Cytochrome P450-derived fatty acid epoxides and diols in angiogenesis and stem cell biology

Cytochrome P450 (CYP) enzymes are frequently referred to as the third pathway for the metabolism of arachidonic acid. While it is true that these enzymes generate arachidonic acid epoxides i.e. the epoxyeicosatrienoic acids (EETs), they are able to accept a wealth of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) to generate a large range of regio- and stereo-isomers with distinct biochemical properties and physiological actions. Probably the best studied are the EETs which have well documented effects on vascular reactivity and angiogenesis. CYP enzymes can also participate in crosstalk with other PUFA pathways and metabolize prostaglandin G₂ and H₂, which are the precursors of effector prostaglandins, to affect macrophage function and lymphangiogenesis. The activity of the PUFA epoxides is thought to be kept in check by the activity of epoxide hydrolases. However, rather than being inactive, the diols generated have been shown to regulate neutrophil activation, stem and progenitor cell proliferation and Notch signaling in addition to acting as exercise-induced lipokines. Excessive production of PUFA diols has also been implicated in pathologies such as severe respiratory distress syndromes, including COVID-19, and diabetic retinopathy. This review highlights some of the recent findings related to this pathway that affect angiogenesis and stem cell biology.

The Consequences of Soluble Epoxide Hydrolase Deletion on Tumorigenesis and Metastasis in a Mouse Model of Breast Cancer

Epoxides and diols of polyunsaturated fatty acids (PUFAs) are bioactive and can influence processes such as tumor cell proliferation and angiogenesis. Studies with inhibitors of the soluble epoxide hydrolase (sEH) in animals overexpressing cytochrome P450 enzymes or following the systemic administration of specific epoxides revealed a markedly increased incidence of tumor metastases. To determine whether PUFA epoxides increased metastases in a model of spontaneous breast cancer, sEH^-/- mice were crossed onto the polyoma middle T oncogene (PyMT) background. We found that the deletion of the sEH accelerated the growth of primary tumors and increased both the tumor macrophage count and angiogenesis. There were small differences in the epoxide/diol content of tumors, particularly in epoxyoctadecamonoenic acid versus dihydroxyoctadecenoic acid, and marked changes in the expression of proteins linked with cell proliferation and metabolism. However, there was no consequence of sEH inhibition on the formation of metastases in the lymph node or lung. Taken together, our results confirm previous reports of increased tumor growth in animals lacking sEH but fail to substantiate reports of enhanced lymph node or pulmonary metastases.

Reprogramming of Metabolism in Kidney Cancer

Metabolic reprogramming is one of the major steps that tumor cells take during cancer progression. This process allows the cells to survive in a nutrient- and oxygen-deprived environment, to become stress tolerant, and to metastasize to different sites. Recent studies have shown that reprogramming happens in stromal cells and involves the cross-talk of the cancer cell/tumor microenvironment. There are similarities between the metabolic reprogramming that occurs in both noncancerous kidney diseases and renal cell carcinoma (RCC), suggesting that such reprogramming is a means by which renal epithelial cells survive injury and repair the tissue, and that RCC cells hijack this system. This article reviews reprogramming of major metabolism pathways in RCC, highlighting similarities and differences from kidney diseases and potential therapeutic strategies against it.

Adamantane-linked isothiourea derivatives suppress the growth of experimental hepatocellular carcinoma via inhibition of TLR4-MyD88-NF-κB signaling

In this study, in vitro cytotoxic effects of seven adamantyl isothiourea derivatives were evaluated against five human tumor cell lines using the MTT assay. Compounds 5 and 6 were found to be the most active derivatives particularly against hepatocellular carcinoma (HCC). To decipher the potential mechanisms involved, in vivo studies were conducted in rats by inducing HCC via chronic thioacetamide (TAA) administration (200 mg/kg, i.p., twice weekly) for 16 weeks. Compounds 5 and 6 were administered to HCC rats, at a dose of 10 mg/kg/day, for further 2 weeks. In vitro and in vivo antitumor activities of compounds 5 and 6 were compared to those of the anticancer drug doxorubicin (DOXO). In the HCC rat model, compounds 5 and 6 significantly reduced serum levels of ALT, AST with ALP and α-fetoprotein. H & E and Masson trichrome staining revealed that both compounds suppressed hepatocyte tumorigenesis and diminished fibrosis, inflammation and other histopathological alterations. Mechanistically, compounds 5 and 6 markedly decreased protein expression levels of α-SMA, sEH, p-NF-κB p65, TLR4, MyD88, TRAF-6, TNF-α, IL-1β and TGF-β1, whereas they increased caspase-3 expression in liver tissues of HCC rats. In most analyses, the effects of compound 6 were more comparable to DOXO than compound 5. These findings suggested that the compounds 5 and 6 displayed in vitro and in vivo cytotoxic potential against HCC, probably via inhibition of TLR4-MyD88-NF-κB signaling.

Discovery of Soluble Epoxide Hydrolase Inhibitors from Chemical Synthesis and Natural Products

Soluble epoxide hydrolase (sEH) is an α/β hydrolase fold protein and widely distributed in numerous organs including the liver, kidney, and brain. The inhibition of sEH can effectively maintain endogenous epoxyeicosatrienoic acids (EETs) levels and reduce dihydroxyeicosatrienoic acids (DHETs) levels, resulting in therapeutic potentials for cardiovascular, central nervous system, and metabolic diseases. Therefore, since the beginning of this century, the development of sEH inhibitors is a hot research topic. A variety of potent sEH inhibitors have been developed by chemical synthesis or isolated from natural sources. In this review, we mainly summarized the interconnected aspects of sEH with cardiovascular, central nervous system, and metabolic diseases and then focus on representative inhibitors, which would provide some useful guidance for the future development of potential sEH inhibitors.

Small Molecule Soluble Epoxide Hydrolase Inhibitors in Multitarget and Combination Therapies for Inflammation and Cancer

The enzyme soluble epoxide hydrolase (sEH) plays a central role in metabolism of bioactive lipid signaling molecules. The substrate-specific hydrolase activity of sEH converts epoxyeicosatrienoic acids (EETs) to less bioactive dihydroxyeicosatrienoic acids. EETs exhibit anti-inflammatory, analgesic, antihypertensive, cardio-protective and organ-protective properties. Accordingly, sEH inhibition is a promising therapeutic strategy for addressing a variety of diseases. In this review, we describe small molecule architectures that have been commonly deployed as sEH inhibitors with respect to angiogenesis, inflammation and cancer. We juxtapose commonly used synthetic scaffolds and natural products within the paradigm of a multitarget approach for addressing inflammation and inflammation induced carcinogenesis. Structural insights from the inhibitor complexes and novel strategies for development of sEH-based multitarget inhibitors are also presented. While sEH inhibition is likely to suppress inflammation-induced carcinogenesis, it can also lead to enhanced angiogenesis via increased EET concentrations. In this regard, sEH inhibitors in combination chemotherapy are described. Urea and amide-based architectures feature prominently across multitarget inhibition and combination chemotherapy applications of sEH inhibitors.

Ligand-based optimization to identify novel 2-aminobenzo[d]thiazole derivatives as potent sEH inhibitors with anti-inflammatory effects

Inhibition of the soluble epoxide hydrolase (sEH) is a promising new therapeutic approach in the treatment of inflammation. Driven by the in-house database product lead 1, a hybridization strategy was utilized for the design of a series of novel benzo [d]thiazol derivatives. To our delight, D016, a byproduct of compound 9, was obtained with an extraordinarily low IC₅₀ value of 0.1 nM but poor physical and chemical properties. After removal of a non-essential urea moiety or replacement of the urea group by an amide group, compounds 15a, 17p, and 18d were identified as promising sEH inhibitors, and their molecular binding modes to sEH were constructed. Furthermore, compounds 15a and 18d exhibited more effective in vivo anti-inflammatory effect than t-AUCB in carrageenan-induced mouse paw edema. Compound 15a also showed moderate metabolic stability with a half-time of 34.7 min. Although 18d was unstable in rat liver microsomes, it might be a "prodrug". In conclusion, this study could provide valuable insights into discovery of new sEH inhibitors, and compounds 15a and 18d were worthy of further development as potential drug candidates to treat inflammation.

ω-3 Polyunsaturated Fatty Acids on Colonic Inflammation and Colon Cancer: Roles of Lipid-Metabolizing Enzymes Involved

Substantial human and animal studies support the beneficial effects of ω-3 polyunsaturated fatty acids (PUFAs) on colonic inflammation and colorectal cancer (CRC). However, there are inconsistent results, which have shown that ω-3 PUFAs have no effect or even detrimental effects, making it difficult to effectively implement ω-3 PUFAs for disease prevention. A better understanding of the molecular mechanisms for the anti-inflammatory and anticancer effects of ω-3 PUFAs will help to clarify their potential health-promoting effects, provide a scientific base for cautions for their use, and establish dietary recommendations. In this review, we summarize recent studies of ω-3 PUFAs on colonic inflammation and CRC and discuss the potential roles of ω-3 PUFA-metabolizing enzymes, notably the cytochrome P450 monooxygenases, in mediating the actions of ω-3 PUFAs.

Resolution of eicosanoid/cytokine storm prevents carcinogen and inflammation-initiated hepatocellular cancer progression

Toxic environmental carcinogens promote cancer via genotoxic and nongenotoxic pathways, but nongenetic mechanisms remain poorly characterized. Carcinogen-induced apoptosis may trigger escape from dormancy of microtumors by interfering with inflammation resolution and triggering an endoplasmic reticulum (ER) stress response. While eicosanoid and cytokine storms are well-characterized in infection and inflammation, they are poorly characterized in cancer. Here, we demonstrate that carcinogens, such as aflatoxin B₁ (AFB₁), induce apoptotic cell death and the resulting cell debris stimulates hepatocellular carcinoma (HCC) tumor growth via an "eicosanoid and cytokine storm." AFB₁-generated debris up-regulates cyclooxygenase-2 (COX-2), soluble epoxide hydrolase (sEH), ER stress-response genes including BiP, CHOP, and PDI in macrophages. Thus, selective cytokine or eicosanoid blockade is unlikely to prevent carcinogen-induced cancer progression. Pharmacological abrogation of both the COX-2 and sEH pathways by PTUPB prevented the debris-stimulated eicosanoid and cytokine storm, down-regulated ER stress genes, and promoted macrophage phagocytosis of debris, resulting in suppression of HCC tumor growth. Thus, inflammation resolution via dual COX-2/sEH inhibition is an approach to prevent carcinogen-induced cancer.

Assessment of the Effect of Sorafenib on Omega-6 and Omega-3 Epoxyeicosanoid Formation in Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer death. The multikinase inhibitor sorafenib is widely used for systemic therapy in advanced HCC. Sorafenib might affect epoxyeicosanoids, as it is also a potent inhibitor of the soluble epoxide hydrolase (sEH), which catalyzes the conversion of epoxides derived from long-chain polyunsaturated fatty acids (PUFAs), such as arachidonic acid (AA) and omega-3 docosahexaenoic acid (DHA), into their corresponding diols. Experimental studies with AA-derived epoxyeicosatrienoic acids (EETs) showed that they can promote tumor growth and metastasis, while DHA-derived 19,20-epoxydocosapentaenoic acid (19,20-EDP) was shown to have anti-tumor activity in mice. In this pilot study, we assessed the effect of sorafenib treatment on the presence of lipid mediators, such as EETs, in blood of the patients with HCC using the lipidomics technology. We found a significant increase in 11,12-EET and 14,15-EET levels in HCC patients treated with sorafenib. Furthermore, while not significant in this small sample set, the data presented indicate that sorafenib can also increase the level of omega-3 DHA-derived 19,20-EDP. While the effect on EETs might hamper the anti-tumor effect of sorafenib, we hypothesize that supplementation of DHA in sorafenib-treated HCC patients could increase the level of 19,20-EDP and thereby enhance its anti-tumor effect.

The MAP3K7-mTOR Axis Promotes the Proliferation and Malignancy of Hepatocellular Carcinoma Cells

Targeted therapy is currently limited for patients with hepatocellular carcinoma (HCC) due to the lack of suitable targets. Kinases play pivotal roles in many cellular biological processes, whereas dysregulation of kinases may lead to various diseases, particularly cancer. However, the role of kinases in HCC malignancy remains unclear. In this study, we employed a kinome small interfering RNA (siRNA) library, comprising 710 kinase-related genes, to screen whether any kinases were essential for cell proliferation in various HCC cell lines. Through a kinome siRNA library screening, we found that MAP3K7 was a crucial gene for HCC cell proliferation. Pharmacological or genetic ablation of MAP3K7 diminished the growth, migration, and invasion of HCC cells, including primary HCC cells. Stable knockdown of MAP3K7 attenuated tumor formation in a spheroid cell culture model and tumor xenograft mouse model. In addition, silencing MAP3K7 reduced the phosphorylation and expression of mammalian target of rapamycin (mTOR) in HCC cells. MAP3K7 expression was positively correlated with mTOR expression in tumors of patients with HCC. Higher co-expression of MAP3K7 and mTOR was significantly associated with poor prognosis of HCC. Taken together, our results revealed that the MAP3K7-mTOR axis might promote tumorigenesis and malignancy, which provides a potential marker or therapeutic target for HCC patients.

Angiogenesis and vascular stability in eicosanoids and cancer

Angiogenesis and inflammation are hallmarks of cancer. Arachidonic acid and other polyunsaturated fatty acids (PUFAs) are primarily metabolized by three distinct enzymatic systems initiated by cyclooxygenases, lipoxygenases, and cytochrome P450 enzymes (CYP) to generate bioactive eicosanoids, including prostanoids, leukotrienes, hydroxyeicosatetraenoic acids, and epoxyeicosatrienoic acids. As some of the PUFA metabolites playing essential roles in inflammatory processes, these pathways have been widely studied as therapeutic targets of inflammation. Because of their anti-inflammatory effects, these pathways were also proposed as anti-cancer targets. However, although the eicosanoids were linked to endothelial cell proliferation and angiogenesis almost two decades ago, it is only recently PUFA metabolites, especially those generated by CYP enzymes and the soluble epoxide hydrolase (sEH), have been recognized as important signaling mediators in physiological and pathological angiogenesis. Despite the fact that tumor growth and invasion are heavily dependent on inner-tumor angiogenesis and influenced by vascular stability, the role played by PUFA metabolites in tumor angiogenesis and vessel integrity has been largely overlooked. This review highlights current knowledge on the function of PUFA metabolites generated by the CYP/sEH pathway in angiogenesis and vascular stability as well as their potential involvement in cancer development.

Development of multitarget agents possessing soluble epoxide hydrolase inhibitory activity

Over the last two decades polypharmacology has emerged as a new paradigm in drug discovery, even though developing drugs with high potency and selectivity toward a single biological target is still a major strategy. Often, targeting only a single enzyme or receptor shows lack of efficacy. High levels of inhibitor of a single target also can lead to adverse side effects. A second target may offer additive or synergistic effects to affecting the first target thereby reducing on- and off-target side effects. Therefore, drugs that inhibit multiple targets may offer a great potential for increased efficacy and reduced the adverse effects. In this review we summarize recent findings of rationally designed multitarget compounds that are aimed to improve efficacy and safety profiles compared to those that target a single enzyme or receptor. We focus on dual inhibitors/modulators that target the soluble epoxide hydrolase (sEH) as a common part of their design to take advantage of the beneficial effects of sEH inhibition.

Inhibition of Soluble Epoxide Hydrolase for Renal Health

A soluble epoxide hydrolase (sEH) mediates the metabolism of epoxy fatty acids to form the corresponding vicinal diols, which are usually inactive or less active than the epoxide substrates. The sEH enzyme presents in many organs, including but not limited to the liver, heart, spleen, lung, and kidney. Here we summarized the changes in the expression and activity of sEH in multiple renal diseases, such as acute kidney injury (AKI), diabetic nephrology (DN), chronic kidney diseases (CKD), hypertension-mediated renal damage, and other renal dysfunctions. We also discussed the pharmacologic effects and the underlying mechanisms of sEH inhibition by using an inhibitor of sEH and/or the generic deletion of sEH on multiple renal diseases. We believe that sEH is a potential therapeutic target for renal dysfunction although the target disease needs further investigation.

Sorafenib and docosahexaenoic acid act in synergy to suppress cancer cell viability: a role of heme oxygenase 1

Background

Docosahexaenoic acid (DHA) is a long chain n-3 polyunsaturated fatty acid that has anticancer activity. Heme oxygenase 1 (HO-1) is a potential therapeutic target due to its cytoprotective activity in cancer cells. We recently reported that DHA induces HO-1 gene transcription in human cancer cells by augmenting the degradation of Bach1 protein, which functions as a negative regulator of HO-1. Since the degradation of Bach1 protein relies on protein phosphorylation, we hypothesized that DHA-induced HO-1 gene transcription could be attenuated by kinase inhibitors, resulting in an enhanced cytotoxicity. Sorafenib, a tyrosine kinase inhibitor, was first applied to test our hypothesis.

Methods

Human cancer cell lines and a xenograft nude mouse model were applied to test our hypothesis. Gene expression was analyzed by western blot analysis and reporter gene assay. Cell viability was analyzed using a colorimetric assay. Isobologram was applied to analyze drug action.

Results

Pretreatment of cancer cells with Sorafenib significantly attenuated DHA-induced degradation of Bach1 protein. Consequently, DHA-induced HO-1 gene transcription was reversed by Sorafenib as evidenced by western blot and reporter gene analysis. Sorafenib acted synergistically with DHA to suppress cancer cell viability in various human cancer cell lines and suppressed tumor xenograft growth in mice fed a fish oil enriched diet (high n-3/DHA), as compared to mice fed a corn oil (high n-6) diet. Screening of the NCI-Oncology Drug Set IV identified a group of anticancer compounds, including Sorafenib, which enhanced DHA’s cytotoxicity, as well as a set of compounds that attenuated DHA’s cytotoxicity.

Conclusions

We demonstrate that sorafenib attenuates DHA-induced HO-1 expression and acts in synergy with DHA to suppress cancer cell viability and tumor growth. Considering the known health benefits of DHA and the clinical effectiveness of Sorafenib, their combination is an attractive therapeutic strategy against cancer.

Synthesis of substituted fluorobenzimidazoles as inhibitors of 5-lipoxygenase and soluble epoxide hydrolase for anti-inflammatory activity

A new series of 4-((5-fluoro-6-(substituted)-1H-benzo[d]imidazol-2-ylthio)methyl)-benzoic acids 4a-o and 2-(5-fluoro-6-(substituted)-1H-benzo[d]imidazol-2-ylthio)-2-methylpropanoic acids 8a-e were synthesized, and their inhibitory potencies against soluble epoxide hydrolase (sEH) and 5-lipoxygenase (5-LOX) were investigated. These molecules were designed based on the combination of 5-LOX and sEH pharmacophores, resulting in hybrid analogs with potent sEH and 5-LOX inhibitory activity. Compound 4g showed remarkable activity with IC₅₀ values of less than 1 μM (0.9 μM) against 5-LOX, while compound 4k displayed promising activity against sEH with IC₅₀  ≤ 1 μM (0.7 μM). These compounds were evaluated for their in vivo potential using the carrageenan-induced rat paw edema assay. Based on the obtained results, the structure-activity relationship was established and a correlation between the activities was observed. Compounds 4f, 4g, 4k, 4n, and 8e showed potent anti-inflammatory activity and significant inhibition of edema (64.13, 67.39, 66.30, 65.21, and 58.69%, respectively) at a dose of 100 mg/kg, comparable to the standard drug ibuprofen (70.65%) at 3 h.

Soluble epoxide hydrolase as a therapeutic target for pain, inflammatory and neurodegenerative diseases

Eicosanoids are biologically active lipid signaling molecules derived from polyunsaturated fatty acids. Many of the actions of eicosanoid metabolites formed by cyclooxygenase and lipoxygenase enzymes have been characterized, however, the epoxy-fatty acids (EpFAs) formed by cytochrome P450 enzymes are newly described by comparison. The EpFA metabolites modulate a diverse set of physiologic functions that include inflammation and nociception among others. Regulation of EpFAs occurs primarily via release, biosynthesis and enzymatic transformation by the soluble epoxide hydrolase (sEH). Targeting sEH with small molecule inhibitors has enabled observation of the biological activity of the EpFAs in vivo in animal models, greatly contributing to the overall understanding of their role in the inflammatory response. Their role in modulating inflammation has been demonstrated in disease models including cardiovascular pathology and inflammatory pain, but extends to neuroinflammation and neuroinflammatory disease. Moreover, while EpFAs demonstrate activity against inflammatory pain, interestingly, this action extends to blocking chronic neuropathic pain as well. This review outlines the role of modulating sEH and the biological action of EpFAs in models of pain and inflammatory diseases.

Sorafenib tosylate inhibits directly necrosome complex formation and protects in mouse models of inflammation and tissue injury

Necroptosis contributes to the pathophysiology of several inflammatory, infectious and degenerative disorders. TNF-induced necroptosis involves activation of the receptor-interacting protein kinases 1 and 3 (RIPK1/3) in a necrosome complex, eventually leading to the phosphorylation and relocation of mixed lineage kinase domain like protein (MLKL). Using a high-content screening of small compounds and FDA-approved drug libraries, we identified the anti-cancer drug Sorafenib tosylate as a potent inhibitor of TNF-dependent necroptosis. Interestingly, Sorafenib has a dual activity spectrum depending on its concentration. In murine and human cell lines it induces cell death, while at lower concentrations it inhibits necroptosis, without affecting NF-κB activation. Pull down experiments with biotinylated Sorafenib show that it binds independently RIPK1, RIPK3 and MLKL. Moreover, it inhibits RIPK1 and RIPK3 kinase activity. In vivo Sorafenib protects against TNF-induced systemic inflammatory response syndrome (SIRS) and renal ischemia–reperfusion injury (IRI). Altogether, we show that Sorafenib can, next to the reported Braf/Mek/Erk and VEGFR pathways, also target the necroptotic pathway and that it can protect in an acute inflammatory RIPK1/3-mediated pathology.

Oxetane Substrates of Human Microsomal Epoxide Hydrolase

Oxetanyl building blocks are increasingly used in drug discovery because of the improved drug-like properties they confer on drug candidates, yet little is currently known about their biotransformation. A series of oxetane-containing analogs was studied and we provide the first direct evidence of oxetane hydrolysis by human recombinant microsomal epoxide hydrolase (mEH). Incubations with human liver fractions and hepatocytes were performed with and without inhibitors of cytochrome P450 (P450), mEH and soluble epoxide hydrolase (sEH). Reaction dependence on NADPH was investigated in subcellular fractions. A full kinetic characterization of oxetane hydrolysis is presented, in both human liver microsomes and human recombinant mEH. In human liver fractions and hepatocytes, hydrolysis by mEH was the only oxetane ring-opening metabolic route, with no contribution from sEH or from cytochrome P450-catalyzed oxidation. Minimally altering the structural elements in the immediate vicinity of the oxetane can greatly modulate the efficiency of hydrolytic ring cleavage. In particular, higher pK_a in the vicinity of the oxetane and an increased distance between the oxetane ring and the benzylic nitrogen improve reaction rate, which is further enhanced by the presence of methyl groups near or on the oxetane. This work defines oxetanes as the first nonepoxide class of substrates for human mEH, which was previously known to catalyze the hydrolytic ring opening of electrophilic and potentially toxic epoxide-containing drugs, drug metabolites, and exogenous organochemicals. These findings will be of value for the development of biologically active oxetanes and may be exploited for the biocatalytic generation of enantiomerically pure oxetanes and diols.

Opportunities and Challenges for Fatty Acid Mimetics in Drug Discovery

Fatty acids beyond their role as an endogenous energy source and storage are increasingly considered as signaling molecules regulating various physiological effects in metabolism and inflammation. Accordingly, the molecular targets involved in formation and physiological activities of fatty acids hold significant therapeutic potential. A number of these fatty acid targets are addressed by some of the oldest and most widely used drugs such as cyclooxygenase inhibiting NSAIDs, whereas others remain unexploited. Compounds orthosterically binding to proteins that endogenously bind fatty acids are considered as fatty acid mimetics. On the basis of their structural resemblance, fatty acid mimetics constitute a family of bioactive compounds showing specific binding thermodynamics and following similar pharmacokinetic mechanisms. This perspective systematically evaluates targets for fatty acid mimetics, investigates their common structural characteristics, and highlights demands in their discovery and design. In summary, fatty acid mimetics share particularly favorable characteristics justifying the conclusion that their therapeutic potential vastly outweighs the challenges in their design.

Screening of soluble epoxide hydrolase inhibitory ingredients from traditional Chinese medicines for anti-inflammatory use

ETHNOPHARMACOLOGICAL RELEVANCE

Inhibition of soluble epoxide hydrolase (sEH) has been extensively reported to be anti-inflammatory in multiple animal models. Some anti-inflammatory traditional Chinese medicines (TCMs) and a few natural compounds were also found to be inhibitory to sEH in vitro.

AIM OF THE STUDY

To determine whether the active intergradient (AI) against sEH of anti-inflammatory TCMs in vitro is anti-inflammatory in vivo and the sEH inhibitory action of the AI contributes to its anti-inflammatory effect in vivo.

MATERIALS AND METHODS

In vitro inhibition assay of the sEH was conducted for the methanol and ethanol extracts of 27 anti-inflammatory TCMs. Two potent extracts were subject to further separation guided by bioassay to afford promising AI against sEH in vitro [Fr.5 of the crude ethanol extract of Rhizoma coptidis (FFCERC)]. Finally, the in vivo anti-inflammatory effect and sEH inhibitory potency of FFCERC was evaluated in a lipopolysacchride (LPS)-challenged murine model of acute systemic inflammation. The inflammatory status was characterized by the inflammatory cytokines TNF-α and interleukin-6 (IL-6) and sEH inhibitory function was evaluated by the plasma levels of epoxyeicosantrienoic acids (EETs) and dihydroxyeicosatrienoic acids (DHETs), which are the sEH mediated substrates and products, respectively.

RESULTS

At the concentration of 25µg/mL, the crude ethanol extracts of 6 TCMs including Herba Asari, Radix Polygalae, Fructus Amomi, Radix Astragali, Radix Scutellariae, and Rhizoma Coptidis were potent against sEH. The crude extracts of Herba Asari and Rhizoma Coptidis were selected for further separation to afford FFCERC as the most promising AI for in vivo evaluation. Oral administration of FFCERC attenuated the significant increase in TNF-α and IL-6 caused by LPS challenge in a dose-dependent manner. In parallel, oral administration of FFCERC shifted the changes in plasma levels of EETs and DHETs caused by LPS-challenge like a synthetic sEH inhibitor.

CONCLUSIONS

A sEH inhibitory AI from Rhizoma Coptidis is anti-inflammatory and the inhibition of sEH contributes to this biological effect, indicating that sEH may be at least one of multiple therapeutic targets for relevant TCMs.

Discovery of a Novel Microsomal Epoxide Hydrolase-Catalyzed Hydration of a Spiro Oxetane

Oxetane moieties are increasingly being used by the pharmaceutical industry as building blocks in drug candidates because of their pronounced ability to improve physicochemical parameters and metabolic stability of drug candidates. The enzymes that catalyze the biotransformation of the oxetane moiety are, however, not well studied. The in vitro metabolism of a spiro oxetane-containing compound AZD1979 [(3-(4-(2-oxa-6-azaspiro[3.3]heptan-6-ylmethyl)phenoxy)azetidin-1-yl)(5-(4-ethoxyphenyl)-1,3,4-oxadiazol-2-yl)methanone] was studied and one of its metabolites, M1, attracted our interest because its formation was NAD(P)H independent. The focus of this work was to elucidate the structure of M1 and to understand the mechanism(s) of its formation. We established that M1 was formed via hydration and ring opening of the oxetanyl moiety of AZD1979. Incubations of AZD1979 using various human liver subcellular fractions revealed that the hydration reaction leading to M1 occurred mainly in the microsomal fraction. The underlying mechanism as a hydration, rather than an oxidation reaction, was supported by the incorporation of (18)O from H2 (18)O into M1. Enzyme kinetics were performed probing the formation of M1 in human liver microsomes. The formation of M1 was substantially inhibited by progabide, a microsomal epoxide hydrolase inhibitor, but not by trans-4-[4-(1-adamantylcarbamoylamino)cyclohexyloxy]benzoic acid, a soluble epoxide hydrolase inhibitor. On the basis of these results, we propose that microsomal epoxide hydrolase catalyzes the formation of M1. The substrate specificity of microsomal epoxide hydrolase should therefore be expanded to include not only epoxides but also the oxetanyl ring system present in AZD1979.

EETs/sEH in diabetes and obesity-induced cardiovascular diseases

Despite the optimization of blood glucose control and the therapeutic management of risk factors, obesity- and diabetes-induced cardiovascular diseases are still major health problems in the United States. Arachidonic acid (AA), an endogenous 20-carbon polyunsaturated fatty acid, is metabolized by cytochrome P450 (CYP) epoxygenases into epoxyeicosatrienoic acids (EETs), which are important lipid mediators with many beneficial effects in type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and obesity- and diabetes-induced cardiovascular diseases. EETs can be further metabolized to less active dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). It has been demonstrated that the use of sEH blockers, which prevent EET degradation, is a promising pharmacological approach to promoting insulin secretion, preventing endothelial dysfunction, decreasing blood pressure, and protecting against target organ damage in obesity and metabolic diseases. This review will focus on biochemistry of CYP monooxygenase system as well as the pharmacology and physiological significance of EETs and sEH. We will also discuss the role of EETs/sEH in T1DM, T2DM, and obesity- and diabetes-induced cardiovascular diseases.

Addition of DHA Synergistically Enhances the Efficacy of Regorafenib for Kidney Cancer Therapy

Kidney cancer is the sixth most common cancer in the United States, and its incidence is increasing. The treatment of this malignancy took a major step forward with the recent introduction of targeted therapeutics, such as kinase inhibitors. Unfortunately, kinase inhibition is associated with the onset of resistance after 1 to 2 years of treatment. Regorafenib, like many multikinase inhibitors, was designed to block the activities of several key kinase pathways involved in oncogenesis (Ras/Raf/MEK/ERK) and tumor angiogenesis (VEGF-receptors), and we have recently shown that it also possesses soluble epoxide hydrolase (sEH) inhibitory activity, which may be contributing to its salutary effects in patients. Because sEH inhibition results in increases in the DHA-derived epoxydocosapentaenoic acids that we have previously described to possess anticancer properties, we asked whether the addition of DHA to a therapeutic regimen in the presence of regorafenib would enhance its beneficial effects in vivo We now show that the combination of regorafenib and DHA results in a synergistic effect upon tumor invasiveness as well as p-VEGFR attenuation. In addition, this combination showed a reduction in tumor weights, greater than each agent alone, in a mouse xenograft model of human renal cell carcinoma (RCC), yielding the expected oxylipin profiles; these data were supported in several RCC cell lines that showed similar results in vitro Because DHA is the predominant component of fish oil, our data suggest that this nontoxic dietary supplement could be administered with regorafenib during therapy for advanced RCC and could be the basis of a clinical trial. Mol Cancer Ther; 15(5); 890-8. ©2016 AACR.

Inhibition of mutant KrasG12D-initiated murine pancreatic carcinoma growth by a dual c-Raf and soluble epoxide hydrolase inhibitor t-CUPM

Mutant Kras and chronic pancreatitis are the most common pathological events involved in human pancreatic cancer. It has been demonstrated that c-Raf is responsible for transmitting signals from mutant Ras to its downstream signals including MEK-ERK and for initiating carcinogenesis. The soluble epoxide hydrolase (sEH), a pro-inflammatory enzyme, generally inactivates anti-inflammatory and anti-pain epoxyeicosatrienoic acids (EETs). Herein, we have synthesized a novel compound of trans-4-{4-[3-(4-chloro-3-trifluoromethyl-phenyl)-ureido]-cyclohexyloxy}-pyridine-2-carboxylic acid methylamide (t-CUPM) via modifying the central phenyl ring of sorafenib and confirmed its dual inhibition of sEH and c-Raf by recombinant kinase activity assay. Pharmacokinetic analysis revealed that oral dosing of t-CUPM resulted in higher blood levels than that of sorafenib throughout the complete time course (48 h). The effect of t-CUPM on the inhibition of mutant Kras(G12D)-initiated murine pancreatic cancer cell growth was determined using the mouse pancreatic carcinoma cell model obtained from LSL-Kras(G12D)/Pdx1-Cre mice and showed that t-CUPM significantly inhibited this murine pancreatic carcinoma cell growth both in vitro and in mice in vivo. Inhibition of mutant Kras-transmitted phosphorylations of cRAF/MEK/ERK was demonstrated in these pancreatic cancer cells using Western blot assay and immunohistochemical approach. Modulation of oxylipin profile, particularly increased EETs/DHET ratio by sEH inhibition, was observed in mice treated with t-CUPM. These results indicate that t-CUPM is a highly potential agent to treat pancreatic cancer via simultaneously targeting c-Raf and sEH.

Soluble Epoxide Hydrolase Inhibitory Activity of Selaginellin Derivatives from Selaginella tamariscina

Selaginellin derivatives 1–3 isolated from Selaginellatamariscina were evaluated for their inhibition of soluble epoxide hydrolase (sEH) to demonstrate their potential for the treatment of cardiovascular disease. All selaginellin derivatives (1–3) inhibited sEH enzymatic activity and PHOME hydrolysis, in a dose-dependent manner, with IC₅₀ values of 3.1 ± 0.1, 8.2 ± 2.2, and 4.2 ± 0.2 μM, respectively. We further determined that the derivatives function as non-competitive inhibitors. Moreover, the predicted that binding sites and interaction between 1–3 and sEH were solved by docking simulations. According to quantitative analysis, 1–3 were confirmed to have high content in the roots of S. tamariscina; among them, selaginellin 3 exhibited the highest content of 189.3 ± 0.0 μg/g.

A model of neuropathic pain induced by sorafenib in the rat: Effect of dimiracetam

BACKGROUND

Sorafenib is a kinase inhibitor anticancer drug whose repeated administration causes the onset of a peripheral painful neuropathy. Notably, the efficacy of common analgesic drugs is not adequate and this often leads pre-mature discontinuation of anticancer therapy. The aim of this study was to establish a rat model of sorafenib-induced neuropathic pain, and to assess the effect of the new anti-neuropathic compound dimiracetam in comparison with gabapentin, pregabalin and duloxetine.

METHODS

Male Sprague-Dawley rats were treated i.v. (10 mg kg(-1)), i.p. (10 and 30 mg kg(-1)) or p.o. (80 and 160 mg kg(-1)) with sorafenib once daily for 21 days. Pain behaviour measurements (cold plate, paw pressure, electronic von Frey) were performed on days 0, 7, 14 and 21.

RESULTS

Sorafenib lowered the paw-licking threshold to non-noxious cold stimuli on day 14 of all protocols evaluated. The i.p. administration resulted in greater efficacy than the other administration routes. Sorafenib treatments did not affect paw-withdrawal responses to non-noxious or to noxious mechanical stimuli. On day 14, dimiracetam (300 mg kg(-1)), gabapentin (100 mg kg(-1)), pregabalin (30 mg kg(-1)) and duloxetine (30 mg kg(-1)) were acutely administered p.o. in sorafenib i.p.-treated rats. A single oral dose of dimiracetam induced a statistically significant increase of the pain threshold 15 min after administration. Pregabalin induced a comparable effect, whereas gabapentin and duloxetine were ineffective. Repeated twice-daily administration of dimiracetam (150 mg kg(-1) p.o.), starting on the first day of i.p sorafenib administration, significantly protected rats from sorafenib-induced decrease in the paw-licking threshold.

CONCLUSIONS

A rat model of sorafenib-induced hypersensitivity to cold stimulation has been established. Dimiracetam and pregabalin are effective in prevention of sorafenib-induced neuropathy in this model.

Potent natural soluble epoxide hydrolase inhibitors from Pentadiplandra brazzeana baillon: synthesis, quantification, and measurement of biological activities in vitro and in vivo

We describe here three urea-based soluble epoxide hydrolase (sEH) inhibitors from the root of the plant Pentadiplandra brazzeana. The concentration of these ureas in the root was quantified by LC-MS/MS, showing that 1, 3-bis (4-methoxybenzyl) urea (MMU) is the most abundant (42.3 μg/g dry root weight). All of the ureas were chemically synthesized, and their inhibitory activity toward recombinant human and recombinant rat sEH was measured. The most potent compound, MMU, showed an IC₅₀ of 92 nM via fluorescent assay and a Ki of 54 nM via radioactivity-based assay on human sEH. MMU effectively reduced inflammatory pain in a rat nociceptive pain assay. These compounds are among the most potent sEH inhibitors derived from natural sources. Moreover, inhibition of sEH by these compounds may mechanistically explain some of the therapeutic effects of P. brazzeana.

Biological evaluation of a novel sorafenib analogue, t-CUPM

Sorafenib (Nexavar®) is currently the only FDA-approved small molecule targeted therapy for advanced hepatocellular carcinoma. The use of structural analogues and derivatives of sorafenib has enabled the elucidation of critical targets and mechanism(s) of cell death for human cancer lines. We previously performed a structure-activity relationship study on a series of sorafenib analogues designed to investigate the inhibition overlap between the major targets of sorafenib Raf-1 kinase and VEGFR-2, and an enzyme shown to be a potent off-target of sorafenib, soluble epoxide hydrolase. In the current work, we present the biological data on our lead sorafenib analogue, t-CUPM, demonstrating that this analogue retains cytotoxicity similar to sorafenib in various human cancer cell lines and strongly inhibits growth in the NCI-60 cell line panel. Co-treatment with the pan-caspase inhibitor, Z-VAD-FMK, failed to rescue the cell viability responses of both sorafenib and t-CUPM, and immunofluorescence microscopy shows similar mitochondrial depolarization and apoptosis-inducing factor release for both compounds. These data suggest that both compounds induce a similar mechanism of caspase-independent apoptosis in hepatoma cells. In addition, t-CUPM displays anti-proliferative effects comparable to sorafenib as seen by a halt in G0/G1 in cell cycle progression. The structural difference between sorafenib and t-CUPM significantly reduces inhibitory spectrum of kinases by this analogue, and pharmacokinetic characterization demonstrates a 20-fold better oral bioavailability of t-CUPM than sorafenib in mice. Thus, t-CUPM may have the potential to reduce the adverse events observed from the multikinase inhibitory properties and the large dosing regimens of sorafenib.

Novel sorafenib-based structural analogues: in-vitro anticancer evaluation of t-MTUCB and t-AUCMB

In the current work, we carried out a mechanistic study on the cytotoxicity of two compounds, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-N-methyl-benzamide (t-AUCMB) and trans-N-methyl-4-{4-[3-(4-trifluoromethoxy-phenyl)-ureido]-cyclohexyloxy}-benzamide (t-MTUCB), that are structurally similar to sorafenib. These compounds show strong cytotoxic responses in various cancer cell lines, despite significant differences in the induction of apoptotic events such as caspase activation and lactate dehydrogenase release in hepatoma cells. Both compounds induce autophagosome formation and LC3I cleavage, but there was little observable effect on mTORC1 or the downstream targets, S6K1 and 4E-binding protein. In addition, there was an increase in the activity of upstream signaling through the IRS1/PI3K/Akt-signaling pathway, suggesting that, unlike sorafenib, both compounds induce mammalian target of rapamycin (mTOR)-independent autophagy. The autophagy observed correlates with mitochondrial membrane depolarization, apoptosis-inducing factor release, and oxidative stress-induced glutathione depletion. However, there were no observable changes in the endoplasmic reticulum-stress markers such as binding immunoglobulin protein, inositol-requiring enzyme-α, phosphorylated eukaryotic initiation factor 2, and the lipid peroxidation marker, 4-hydroxynonenal, suggesting endoplasmic reticulum-independent oxidative stress. Finally, these compounds do not have the multikinase inhibitory activity of sorafenib, which may be reflected in their difference in the ability to halt cell cycle progression compared with sorafenib. Our findings indicate that both compounds have anticancer effects comparable with sorafenib in multiple cell lines, but they induce significant differences in apoptotic responses and appear to induce mTOR-independent autophagy. t-AUCMB and t-MTUCB represent novel chemical probes that are capable of inducing mTOR-independent autophagy and apoptosis to differing degrees, and may thus be potential tools for further understanding the link between these two cellular stress responses.

Stabilized epoxygenated fatty acids regulate inflammation, pain, angiogenesis and cancer

Epoxygenated fatty acids (EpFAs), which are lipid mediators produced by cytochrome P450 epoxygenases from polyunsaturated fatty acids, are important signaling molecules known to regulate various biological processes including inflammation, pain and angiogenesis. The EpFAs are further metabolized by soluble epoxide hydrolase (sEH) to form fatty acid diols which are usually less-active. Pharmacological inhibitors of sEH that stabilize endogenous EpFAs are being considered for human clinical uses. Here we review the biology of ω-3 and ω-6 EpFAs on inflammation, pain, angiogenesis and tumorigenesis.

Optimization of antitumor modulators of pre-mRNA splicing

The spliceosome regulates pre-mRNA splicing, which is a critical process in normal mammalian cells. Recently, recurrent mutations in numerous spliceosomal proteins have been associated with a number of cancers. Previously, natural product antitumor agents have been shown to interact with one of the proteins that is subject to recurrent mutations (SF3B1). We report the optimization of a class of tumor-selective spliceosome modulators that demonstrate significant in vivo antitumor activity. This optimization culminated in the discovery of sudemycin D6, which shows potent cytotoxic activity in the melanoma line SK-MEL-2 (IC50 = 39 nM) and other tumor cell lines, including JeKo-1 (IC50 = 22 nM), HeLa (IC50 = 50 nM), and SK-N-AS (IC50 = 81 nM). We also report improved processes for the synthesis of these compounds. Our work supports the idea that sudemycin D6 is worthy of further investigation as a novel preclinical anticancer agent with application in the treatment of numerous human cancers.

Angiogenic and signalling proteins correlate with sensitivity to sequential treatment in renal cell cancer

BACKGROUND

We aimed to study key signalling proteins involved in angiogenesis and proliferation on the response to inhibitors of tyrosine kinases and mammalian target of rapamycin in first- and in second-line treatment of renal cell carcinoma (RCC).

METHODS

In a panel of human RCC tumours, in vitro and in nude mice, we evaluated the effect of sunitinib, sorafenib and everolimus, alone and in sequence, on tumour growth and expression of signalling proteins involved in proliferation and resistance to treatment.

RESULTS

We demonstrated that, as single agents, sunitinib, sorafenib and everolimus share similar activity in inhibiting cell proliferation, signal transduction and vascular endothelial growth factor (VEGF) secretion in different RCC models, both in vitro and in tumour xenografts. Pre-treatment with sunitinib reduced the response to subsequent sunitinib and sorafenib but not to everolimus. Inability by sunitinib to persistently inhibit HIF-1, VEGF and pMAPK anticipated treatment resistance in xenografted tumours. After first-line sunitinib, second-line treatment with everolimus was more effective than either sorafenib or rechallenge with sunitinib in interfering with signalling proteins, VEGF and interleukin-8, translating into a significant advantage in tumour growth inhibition and mice survival.

CONCLUSION

We demonstrated that a panel of angiogenic and signalling proteins can correlate with the onset of resistance to sunitinib and the activity of everolimus in second line.

Synthesis and biological evaluation of sorafenib- and regorafenib-like sEH inhibitors

To reduce the pro-angiogenic effects of sEH inhibition, a structure-activity relationship (SAR) study was performed by incorporating structural features of the anti-angiogenic multi-kinase inhibitor sorafenib into soluble epoxide hydrolase (sEH) inhibitors. The structural modifications of this series of molecules enabled the altering of selectivity towards the pro-angiogenic kinases C-RAF and vascular endothelial growth factor receptor-2 (VEGFR-2), while retaining their sEH inhibition. As a result, sEH inhibitors with greater potency against C-RAF and VEGFR-2 were obtained. Compound 4 (t-CUPM) possesses inhibition potency higher than sorafenib towards sEH but similar against C-RAF and VEGFR-2. Compound 7 (t-CUCB) selectively inhibits sEH, while inhibiting HUVEC cell proliferation, a potential anti-angiogenic property, without liver cancer cell cytotoxicity. The data presented suggest a potential rational approach to control the angiogenic responses stemming from sEH inhibition.

Inhibition of soluble epoxide hydrolase by fulvestrant and sulfoxides

The soluble epoxide hydrolase (sEH) is a key enzyme in the metabolism of epoxy-fatty acids, signaling molecules involved in numerous biologies. Toward finding novel inhibitors of sEH, a library of known drugs was tested for inhibition of sEH. We found that fulvestrant, an anticancer agent, is a potent (KI=26 nM) competitive inhibitor of sEH. From this observation, we found that alkyl-sulfoxides represent a new kind of pharmacophore for the inhibition of sEH.

From a multipotent stilbene to soluble epoxide hydrolase inhibitors with antiproliferative properties

Inspired by nature: Natural product isopropylstilbene was identified as an inhibitor of soluble epoxide hydrolase exhibiting antiproliferative properties. Following the natural product inspired design approach, a library of (E)-styryl-1H-benzo[d]imidazoles was synthesized and evaluated with recombinant enzyme and on several cancer cell lines.