Discovery of a novel 2,5-dihydroxycinnamic acid-based 5-lipoxygenase inhibitor that induces apoptosis and may impair autophagic flux in RCC4 renal cancer cells

Single and multiple inhibitors of the biosynthesis of 5-, 12-, 15-lipoxygenase products derived from cinnamyl-3,4-dihydroxy-α-cyanocinnamate: Synthesis and structure-activity relationship

The involvement of lipoxygenases in various pathologies, combined with the unavailability of safe and effective inhibitors of the biosynthesis of their products, is a source of inspiration for the development of new inhibitors. Based on a structural analysis of known inhibitors of lipoxygenase products biosynthesis, a comprehensive structure-activity study was carried out, which led to the discovery of several novel compounds (16a-c, 17a) demonstrating promising potency to inhibit the biosynthesis of products of 5-, 12- and 15-LO. Compounds 16b and 16c outperformed zileuton (1), the only FDA-approved 5-LO inhibitor, as well as known inhibitors such as caffeic acid phenethyl ester (CAPE (2)) and cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC (4)). However, the introduction of a cyano group at the α-position of the carbonyl abolished the activity. Compounds 16a and 17a also inhibited the biosynthesis of 12- and 15-LO products. Compounds 16a, 17a far surpassed baicalein, a known 12-LO inhibitor, as inhibitors of 12-LO products biosynthesis. Compound 17a and CDC (4) showed equivalent inhibition of LO products, proposing that the double bond in the ester moiety is not necessary for the inhibitory activity. The introduction of the cyano group, as in compound 17a, at the α-position of the carbonyl in compound 16a significantly reduced the inhibitory activity against the biosynthesis of 15-LO products. In addition to the interactions with residues His372 and Phe421 also found with zileuton and CAPE, compounds 16a and 16c each interact with residue His367 as shown by molecular docking. This new interaction may explain their high affinity with the 5-LO active site.

Lipoxygenases at the Intersection of Infection and Carcinogenesis

The persisting presence of opportunistic pathogens like Pseudomonas aeruginosa poses a significant threat to many immunocompromised cancer patients with pulmonary infections. This review highlights the complexity of interactions in the host's defensive eicosanoid signaling network and its hijacking by pathogenic bacteria to their own advantage. Human lipoxygenases (ALOXs) and their mouse counterparts are integral elements of the innate immune system, mostly operating in the pro-inflammatory mode. Taking into account the indispensable role of inflammation in carcinogenesis, lipoxygenases have counteracting roles in this process. In addition to describing the structure-function of lipoxygenases in this review, we discuss their roles in such critical processes as cancer cell signaling, metastases, death of cancer and immune cells through ferroptosis, as well as the roles of ALOXs in carcinogenesis promoted by pathogenic infections. Finally, we discuss perspectives of novel oncotherapeutic approaches to harness lipoxygenase signaling in tumors.

Caffeic acid phenethyl ester analogues as selective inhibitors of 12-lipoxygenase product biosynthesis in human platelets

The inflammatory response is an essential process for the host defence against pathogens. Lipid mediators are important in coordinating the pro-inflammatory and pro-resolution phases of the inflammatory process. However, unregulated production of these mediators has been associated with chronic inflammatory diseases such as arthritis, asthma, cardiovascular diseases, and several types of cancer. Therefore, it is not surprising that enzymes implicated in the production of these lipid mediators have been targeted for potential therapeutic approaches. Amongst these inflammatory molecules, the 12-hydroxyeicosatetraenoic acid (12(S)-HETE) is abundantly produced in several diseases and is primarily biosynthesized via the platelet's 12-lipoxygenase (12-LO) pathway. To this day, very few compounds selectively inhibit the 12-LO pathway, and most importantly, none are currently used in the clinical settings. In this study, we investigated a series of polyphenol analogues of natural polyphenols that inhibit the 12-LO pathway in human platelets without affecting other normal functions of the cell. Using an ex vivo approach, we found one compound that selectively inhibited the 12-LO pathway, with IC50 values as low as 0.11 µM, with minimal inhibition of other lipoxygenase or cyclooxygenase pathways. More importantly, our data show that none of the compounds tested induced significant off-target effects on either the platelet's activation or its viability. In the continuous search for specific and better inhibitors targeting the regulation of inflammation, we characterized two novel inhibitors of the 12-LO pathway that could be promising for subsequent in vivo studies.

Ginsenoside Rh2: A shining and potential natural product in the treatment of human nonmalignant and malignant diseases in the near future

BACKGROUND

Ginseng is well-known as one of the most valuable and commonly used Chinese medicines not only in ancient China but also worldwide including East, Russia, Southeast Asia, North America and some Western European countries. Ginsenosides, as one of the main high active components of Ginseng, have various pharmacological activities, such as anti-inflammatory, antianaphylaxis, anti-depression, and anticancer activities. Ginsenoside Rh2 (Rh2), one of the major bioactive ginsenosides in Panax ginseng, also exhibits versatile pharmacological activities, such as increasing non-specific resistance and specific immune response, improving cardiac function and fibrosis, anti-inflammatory effects and antitumor effects, which may serve as an excellent medicinal potential.

PURPOSE

As one of hundreds of ginsenosides being identified from ginseng, Rh2 exerts a markedly pharmacological effect on various diseases without severe toxicity, it has attracted many researchers 'attention. Although Rh2 plays important roles in some animal models and cell lines to simulate human diseases, its underlying molecular mechanisms have yet to be determined. During the past ten years, nearly 450 studies on Rh2 in the treatment of complex disease have been reported, however, up to now, no comprehensive reviews about the roles of Rh2 in animal models and cellular lines of human nonmalignant and malignant diseases have been conducted.

METHOD

We searched articles on ginsenoside-related diseases from December 2010 to February 2023 in peer-reviewed and nonclinical databases, which include Web of Science, Scopus, PubMed, China national knowledge internet and Medline, and using the following keywords: Ginsenoside Rh2, Human diseases, Cancer, Mechanisms, Chinese herbal medicine, Natural products and Signaling pathway.

RESULTS

Therefore, in this review, we make a comprehensive summary on the roles of Rh2 and support the potential mechanisms of Rh2 according to the disease classification, including nonmalignant disease such as ulcerative colitis, neuropathic pain, Asthma, myocardial injury, depression and malignant disease such as breast cancer, colorectal cancer, hepatocellular carcinoma and gastric cancer. Finally, the combination therapy of Rh2 and other medications in human diseases are summarized, apart from that, there are other problems such as the bioavailability of oral administration Rh2 to be overcome in following research.

CONCLUSION

These findings provide strong evidence that Ginsenoside Rh2 plays important roles in the treatment of nonmalignant and malignant diseases.

Lipids as Targets for Renal Cell Carcinoma Therapy

Kidney cancer is among the top ten most common cancers to date. Within the kidney, renal cell carcinoma (RCC) is the most common solid lesion occurring. While various risk factors are suspected, including unhealthy lifestyle, age, and ethnicity, genetic mutations seem to be a key risk factor. In particular, mutations in the von Hippel-Lindau gene (Vhl) have attracted a lot of interest since this gene regulates the hypoxia inducible transcription factors HIF-1α and HIF-2α, which in turn drive the transcription of many genes that are important for renal cancer growth and progression, including genes involved in lipid metabolism and signaling. Recent data suggest that HIF-1/2 are themselves regulated by bioactive lipids which make the connection between lipids and renal cancer obvious. This review will summarize the effects and contributions of the different classes of bioactive lipids, including sphingolipids, glycosphingolipids, eicosanoids, free fatty acids, cannabinoids, and cholesterol to renal carcinoma progression. Novel pharmacological strategies interfering with lipid signaling to treat renal cancer will be highlighted.

No Time to Die: How Kidney Cancer Evades Cell Death

The understanding of the pathogenesis of renal cell carcinoma led to the development of targeted therapies, which dramatically changed the overall survival rate. Nonetheless, despite innovative lines of therapy accessible to patients, the prognosis remains severe in most cases. Kidney cancer rarely shows mutations in the genes coding for proteins involved in programmed cell death, including p53. In this paper, we show that the molecular machinery responsible for different forms of cell death, such as apoptosis, ferroptosis, pyroptosis, and necroptosis, which are somehow impaired in kidney cancer to allow cancer cell growth and development, was reactivated by targeted pharmacological intervention. The aim of the present review was to summarize the modality of programmed cell death in the pathogenesis of renal cell carcinoma, showing in vitro and in vivo evidence of their potential role in controlling kidney cancer growth, and highlighting their possible therapeutic value.

Deoxyschizandrin Inhibits the Proliferation, Migration, and Invasion of Bladder Cancer Cells through ALOX5 Regulating PI3K-AKT Signaling Pathway

Objective

Deoxyschizandrin has a significant inhibitory effect on a variety of tumor cells. However, the effect of Deoxyschizandrin on bladder cancer cells and its mechanism are still unclear.

Methods

Bladder cancer cells were treated with different concentrations of Deoxyschizandrin for 24 h, 48 h, and 72 h. The inhibition rate of cell proliferation was detected by CCK-8 assay. The changes of cell migration and invasion were detected by wound healing and Transwell assay. Based on the structure of Deoxyschizandrin, the protein targets of Deoxyschizandrin were predicted by bioinformatics database and verified by RNA and protein. Then, the expressions of ALOX5 and PI3K-AKT signaling pathway proteins were detected by Western blot in bladder cancer cells treated with Deoxyschizandrin.

Result

Deoxyschizandrin inhibited the proliferation, migration, and invasion of bladder cancer cells in a time- and concentration-dependent manner. Bioinformatics analysis showed that Deoxyschizandrin had 100 protein targets; among them, the score of ALOX5 was the highest, and the mRNA and protein levels of ALOX5 decreased after treatment with different concentrations of Deoxyschizandrin. Western blot results showed that compared with the control group, Deoxyschizandrin could significantly reduce the expression of p-PI3K and p-AKT, and overexpression of ALOX5 could significantly enhance the expression of p-PI3K and p-AKT. Compared with Deoxyschizandrin or overexpression of ALOX5, the expression of p-PI3K and p-AKT of Deoxyschizandrin combined with overexpression of ALOX5 recovered.

Conclusion

Deoxyschizandrin inhibits the proliferation, migration, and invasion of bladder cancer cells through ALOX5 regulating PI3K-AKT signaling pathway.

Ketone Analog of Caffeic Acid Phenethyl Ester Exhibits Antioxidant Activity via Activation of ERK-Dependent Nrf2 Pathway

Due to their robust antioxidant properties, phenolic acids and their analogs are extensively studied for their ability to activate cellular antioxidant pathways, including nuclear factor (erythroid-derived-2)-like 2 (Nrf2)-antioxidant response element (ARE) pathway. Caffeic, ferulic, and gallic acid are well-studied members of phenolic acids. Constant efforts are made to improve the pharmacological effects and bioavailability of phenolic acids by synthesizing their chemical derivatives. This study determines how modifications of the chemical structure of these phenolic acids affect their antioxidant and cytoprotective activities. We have selected six superior antioxidant compounds (12, 16, 26, 35, 42, and 44) of the 48 caffeic acid phenethyl ester (CAPE) analogs based on their ability to scavenge free radicals in vitro using standard antioxidant assays. These compounds exhibited minimal toxicity as indicated by cell cycle and cytochrome C release assays. Among these compounds, 44, the ketone analog of CAPE, exhibited the ability to increase p-Nrf2 (Ser40) levels in 293T cells (p < 0.05). Further, 44, exhibited its antioxidant effect in Drosophila Melanogaster as indicated by an increase in mRNA levels of Nrf2 and GPx (p < 0.05). Finally, the ability of 44 to activate the antioxidant pathway was abolished in the presence of extracellular signal-regulated kinase (ERK) inhibitor in 293T cells. Thus, we identify 44, the ketone analog of CAPE, as a unique antioxidant molecule with the function of ERK-mediated Nrf2 activation.

Renal cell carcinoma therapy: Current and new drug candidates

Renal cell carcinoma (RCC) is the most common and lethal tumor of the urological system. Curative treatment of localized RCC includes nephrectomy, radio-ablation, and active surveillance, whereas metastatic RCC (mRCC) requires a combination of surgery and systemic therapy. Response to conventional therapy is limited but, recently, many novel therapies for mRCC have emerged, including targeted therapies and new immunotherapeutic agents. Nevertheless, development of resistance and limited durable responses demand new anticancer candidates with improved selectivity and efficacy. In this review, we summarize recent preclinical studies of novel natural and synthetic compounds to treat RCC, detailing their mechanisms of action and anticancer activities.

Lipoxygenase Inhibitors as Cancer Chemopreventives: Discovery, Recent Developments and Future Perspectives

BACKGROUND

Leukotrienes (LTs) constitute a bioactive group of Polyunsaturated Fatty Acid (PUFA) metabolites molded by the enzymatic activity of lipoxygenase (LO) and have a pivotal role in inflammation and allergy. Evidence is accumulating both by in vitro cell culture experiments and animal tumor model studies in support of the direct involvement of aberrant metabolism of arachidonic acid (ACD) in the development of several types of human cancers such as lung, prostate, pancreatic and colorectal malignancies. Several independent experimental data suggest a correlation between tumoral cells viability and LO gene expression, especially, 5-lipoxygenase (5-LO). Overexpressed 5-LO cells live longer, proliferate faster, invade more effectively through extracellular matrix destruction and activate the anti-apoptotic signaling mechanisms more intensively compared to the normal counterparts. Thus, some groups of lipoxygenase inhibitors may be effective as promising chemopreventive agents.

METHODS

A structured search of bibliographic databases for peer-reviewed research literature regarding the role of LO in the pathogenesis of cancer was performed. The characteristics of screened papers were summarized and the latest advances focused on the discovery of new LO inhibitors as anticancer agents were discussed.

RESULTS

More than 180 papers were included and summarized in this review; the majority was about the newly designed and synthesized 5-LO inhibitors as anti-inflammatory and anticancer agents. The enzyme's structure, 5-LO pathway, 5-LO inhibitors structure-activity relationships as well as the correlation between these drugs and a number of most prevalent human cancers were described. In most cases, it has been emphasized that dual cyclooxygenase-2/5-lipoxygenase (COX-2/5-LO) or dual 5-lipoxygenase/microsomal prostaglandin E synthase-1 (5-LO/mPGES-1) inhibitors possess considerable inhibitory activities against their target enzymes as well as potent antiproliferative effects. Several papers disclosing 5-lipoxygenase activating protein (FLAP) antagonists as a new group of 5-LO activity regulators are also subject to this review. Also, the potential of 12-lipoxygenase (12- LO) and 15-lipoxygenase (15-LO) inhibitors as chemopreventive agents was outlined to expand the scope of new anticancer agents discovery. Some peptides and peptidomimetics with anti-LT activities were described as well. In addition, the cytotoxic effects of lipoxygenase inhibitors and their adverse effects were discussed and some novel series of natural-product-derived inhibitors of LO was also discussed in this review.

CONCLUSION

This review gives insights into the novel lipoxygenase inhibitors with anticancer activity as well as the different molecular pharmacological strategies to inhibit the enzyme effectively. The findings confirm that certain groups of LO inhibitors could act as promising chemopreventive agents.

Antimyeloma Potential of Caffeic Acid Phenethyl Ester and Its Analogues through Sp1 Mediated Downregulation of IKZF1-IRF4-MYC Axis

Caffeic acid phenethyl ester (CAPE, 2), a natural compound from propolis, is a well-documented antitumor agent with nuclear factor kappa B (NF-κB) inhibitory activity. Key transcription factors regulated by NF-κB, namely, interferon regulatory factor-4 (IRF4) and octameric binding protein-2 (OCT2), are implicated in the tumorigenesis of multiple myeloma (MM), an incurable bone marrow cancer. Adverse effects and resistance to current chemotherapeutics pose a great challenge for MM treatment. Hence, the structure-activity relationships of CAPE (2) and 21 of its analogues were evaluated for their antimyeloma potential. Preclinical evaluation revealed that CAPE (2) and the 3-phenylpropyl (4), 2,5-dihydroxycinnamic acid 3-phenylpropyl ester (17), and 3,4-dihydroxycinnamic ether (22) analogues inhibited human myeloma cell growth. Analogue 4 surpassed CAPE (2) and lenalidomide in showing strong apoptotic effects with a remarkable decrease in IRF4 levels. The analogue 17 exhibited the most potent anti-MM activity. The downregulation of specificity protein 1 (Sp1) and the IKZF1-IRF4-MYC axis by CAPE (2) analogues 4 and 17 revealed their novel mechanism of action. The analogues showed no adverse cytotoxic effects on normal human cells and exhibited appropriate in silico pharmacokinetic properties and drug-likeness. These findings suggest the promising application of CAPE (2) analogues to target Ikaros (IKZF1)/IRF4 addiction, the so-called Achilles heel of myeloma, for better treatment outcomes.

Anise Hyssop Agastache foeniculum Increases Lifespan, Stress Resistance, and Metabolism by Affecting Free Radical Processes in Drosophila

Anise hyssop, Agastache foeniculum, is a widely used medicinal herb with known antioxidant properties. We studied how dietary supplementation with dried A. foeniculum leaf powder affected physiological and metabolic traits as well as activities of antioxidant enzymes and markers of oxidative stress in Drosophila melanogaster. Dietary hyssop extended the lifespan in a sex and genotype independent manner over a broad range of concentrations up to 30 mg/ml. Dietary supplementation with the herb significantly increased fecundity, resistance to oxidative stress and starvation. Higher transcript levels of Drosophila insulin-like peptide (dilp2) and decreased dilp3 and dilp6 transcripts together with increased levels of glycogen and triacylglycerols support an alteration of insulin signaling by the plant extract. Increased enzymatic activities of superoxide dismutase and aconitase as well as elevated protein and low molecular mass thiols also supported an alteration of free radical process in flies treated with dietary A. foeniculum leaf powder. Thus, physiological and metabolic traits as well as free radical processed may be affected by active compounds detected in extracts of anise hyssop leaves and contribute to the increased lifespan and reproductive (egg-laying) activity observed.

New Zileuton-Hydroxycinnamic Acid Hybrids: Synthesis and Structure-Activity Relationship towards 5-Lipoxygenase Inhibition

A novel series of zileuton-hydroxycinnamic acid hybrids were synthesized and screened as 5-lipoxygenase (5-LO) inhibitors in stimulated HEK293 cells and polymorphonuclear leukocytes (PMNL). Zileuton’s (1) benzo[b]thiophene and hydroxyurea subunits combined with hydroxycinnamic acid esters’ ester linkage and phenolic acid moieties were investigated. Compound 28, bearing zileuton’s (1) benzo[b]thiophene and sinapic acid phenethyl ester’s (2) α,β-unsaturated phenolic acid moiety 28, was shown to be equipotent to zileuton (1), the only clinically approved 5-LO inhibitor, in stimulated HEK293 cells. Compound 28 was three times as active as zileuton (1) for the inhibition of 5-LO in PMNL. Compound 37, bearing the same sinapic acid (3,5-dimethoxy-4-hydroxy substitution) moiety as 28, combined with zileuton’s (1) hydroxyurea subunit was inactive. This result shows that the zileuton’s (1) benzo[b]thiophene moiety is essential for the inhibition of 5-LO product biosynthesis with our hydrids. Unlike zileuton (1), Compound 28 formed two π–π interactions with Phe177 and Phe421 as predicted when docked into 5-LO. Compound 28 was the only docked ligand that showed a π–π interaction with Phe177 which may play a part in product specificity as reported.

The tumour microenvironment and metabolism in renal cell carcinoma targeted or immune therapy

Renal cell carcinoma (RCC) is one of the most common tumours of the urinary system, and is insidious and not susceptible to chemoradiotherapy. As the most common subtype of RCC (70-80% of cases), clear cell renal cell carcinoma (ccRCC) is characterized by the loss of von Hippel-Lindau and the accumulation of robust lipid and glycogen. For advanced RCC, molecular-targeted drugs, tyrosine kinase inhibitors (TKIs) and the immune checkpoint inhibitors (ICIs) have been increasingly recommended and investigated. Due to the existence of a highly dynamic, adaptive and heterogeneous tumour microenvironment (TME), and due to the glucose and lipid metabolism in RCC, this cancer may be accompanied by various types of resistance to TKIs and ICIs. With the increased production of lactate, nitric oxide, and other new by-products of metabolism, novel findings of the TME and key metabolic enzymes drived by HIF and other factors have been increasingly clarified in RCC carcinogenesis and therapy. However, there are few summaries of the TME and tumour metabolism for RCC progression and therapy. Here, we summarize and discuss the relationship of the important implicated characteristics of the TME as well as metabolic molecules and RCC carcinogenesis to provide prospects for future treatment strategies to overcome TME-related resistance in RCC.

Phenolic acid phenethylesters and their corresponding ketones: Inhibition of 5-lipoxygenase and stability in human blood and HepaRG cells

5-lipoxygenase (5-LO) catalyzes the biosynthesis of leukotrienes, potent lipid mediators involved in inflammatory diseases, and both 5-LO and the leukotrienes are validated therapeutic targets. Caffeic acid phenethyl ester (CAPE) is an effective inhibitor of 5-LO and leukotriene biosynthesis but is susceptible to hydrolysis by esterases. In this study a number of CAPE analogues were synthesized with modifications to the caffeoyl moiety and the replacement of the ester linkage with a ketone. Several new molecules showed better inhibition of leukotriene biosynthesis than CAPE in isolated human neutrophils and in whole blood with IC50 values in the nanomolar (290-520 nmol/L) and low micromolar (1.0-2.3 µmol/L) ranges, respectively. Sinapic acid and 2,5-dihydroxy derivatives were more stable than CAPE in whole blood, and ketone analogues were degraded more slowly in HepaRG hepatocyte cultures than esters. All compounds underwent modification consistent with glucuronidation in HepaRG cultures as determined using LC-MS/MS analysis, though the modified sinapoyl ketone (10) retained 50% of its inhibitory activity after up to one hour of incubation. This study has identified at least one CAPE analogue, compound 10, that shows favorable properties that warrant further in vivo investigation as an antiinflammatory compound.