Screening for natural products that affect Wnt signaling activity

Search for natural products from actinomycetes of the genus Nocardia

The genus Nocardia are gram-positive bacteria, many of which possess pathogenicity and infect human lungs, skin, brain, and other organs. Since research on the genus Nocardia has not progressed as rapidly as that on the genus Streptomyces, the genus Nocardia is considered a useful undeveloped resource for exploring natural products. On the other hand, when the genus Nocardia infects the human body, the strains are attacked by immune cells such as macrophages. Therefore, we suggested a new method for screening natural products by culturing the genus Nocardia in the presence of animal cells. In this review, we describe our recent results in searching for natural products from the genus Nocardia.

Molecular docking analysis of marine phytochemicals with BACE-1

Alzheimer's disease (AD), a debilitating neurodegenerative condition, is characterized by progressive cognitive decline brought about by the deposition of amyloid beta (Aβ) plaques in the brain initiates downstream neuronal dysfunction and death in AD pathogenesis. The β-secretase (BACE-1) enzyme plays a crucial role in generating Aβ from amyloid precursor protein (APP). Hence, we report the virtual screening of marine phytochemicals as BACE-1 inhibitors. 2583 compounds, retrieved from Comprehensive Marine Natural Product Database (CMNPD), were primarily screened for drug-likeliness and blood-brain barrier permeability using admetSAR 2.0 and in-house BBBper tool and resulted in a total of 635 phytochemicals, selected for further docking studies using BACE-1 as target receptor and Atabecestat as standard BACE-1 inhibitor. Seven of 635 compounds docked against BACE-1, showed better binding affinities than Atabecestat, with the red algal metabolite lactodehydrothyrsiferol showing lowest binding energy of -10.83 kcal/mol. These compounds are worth investigating further to assess their neuroprotective efficacy and pharmacokinetic properties. The study also provides a rational framework to uncover novel pharmacophores from marine sources for AD therapy acting through BACE-1 inhibition.

[Learning from Natural Products: Study on Actinomycetes of the Genus Nocardia]

The genus Nocardia comprises gram-positive bacteria, most of which are pathogenic and cause opportunistic infections of the lungs, skin, and brain in humans. Based on a collaboration study with the Medical Mycology Research Center, Chiba University, we focused on Nocardia actinomycetes as a new natural-product resource. First, by culturing (monoculture) Nocardia in various media, we isolated a new aminocyclitol nabscessin A from Nocardia abscessus IFM10029T and a new γ-lactone inohanalactone from Nocardia inohanaensis IFM0092T. On the other hand, by imitating the state in which the genus Nocardia actinomycete infects animal cells and culturing the genus in the presence of animal cells (coculture), this genus was expected to produce new compounds through interactions with the animal cells. Using mouse macrophage-like cells (J774.1) as animal cells, a new pantothenic acid amide derivative and a cyclic peptide, nocarjamide, with Wnt signal activation activity were isolated from Nocardia tenerifensis IFM10554T strain.

Phytochemical Investigation of Egyptian Riverhemp: A Potential Source of Antileukemic Metabolites

As part of our research group’s continuous efforts to find alternative treatments for cancer, the aqueous ethanol extract of Sesbania sesban L. Merr. (SS, Egyptian riverhemp) demonstrated an antileukemic activity against K562 cell line. Bioguided fractionation of SS leaves hydroethanolic extract resulted in the isolation of one new compound (33) named as hederatriol 3-O-β-D-glucuronic acid methyl ester as well as 34 known compounds. Seven compounds ((34), (22), (20), (24), (21), (19), and (35)) showed high antiproliferative effects (IC50 = 22.3, 30.8, 31.3, 33.7, 36.6, 37.5, and 41.5 μM, respectively), while four compounds ((32), (5), (29), and (1)) showed milder activities (IC50 = 56.4, 67.6, 83.3, and 112.3 μM, respectively). A mechanistic study was further carried out on a molecular genetics level against several transcription factors signaling pathways that are incorporated in the incidence of cancer. The results showed that compounds (22) and (21) demonstrated a specific inhibition of Wnt pathway (IC50 = 3.8 and 4.6 μM, respectively), while compound (22) showed a specific inhibition of Smad pathway (IC50 = 3.8 μM). Compound (34) strongly altered the signaling of Smad and E2F pathways (IC50 = 5 μM). The bioactive metabolites were further investigated in silico by docking against several targets related to K562 cell line. The results showed that compounds (22) and (34) exhibited a strong binding affinity towards topoisomerase (docking score = −7.81 and −9.30 Kcal/Mole, respectively). Compounds (22) and (34) demonstrated a strong binding affinity towards EGFR-tyrosine kinase (docking score = −7.12 and −7.35 Kcal/Mole, respectively). Moreover, compound (34) showed a strong binding affinity towards Abl kinase (docking score = −7.05 Kcal/Mole).

Thannilignan glucoside and 2-(β-glucopyranosyl)-3-isoxazolin-5-one derivative, two new compounds isolated from Terminalia bellirica

Two new compounds, thannilignan 9-O-β-glucoside (1) and 2-(β-glucopyranosyl)-3-isoxazolin-5-one derivative (2), and seven known compounds were isolated from the methanol extract of Terminalia bellirica leaves, collected in Bangladesh. The structures of the compounds were elucidated using spectroscopic analysis. Among these isolated compounds, corilagin (3) was cytotoxic against human gastric adenocarcinoma cell line AGS at an IC₅₀ of 20.8 μM, and β-D-glucopyranose 1,3,6-trigallate (4) exhibited the ability to overcome tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance.

Screening study of cancer-related cellular signals from microbial natural products

To identify bioactive natural products from various natural resources, such as plants and microorganisms, we investigated programs to screen for compounds that affect several cancer-related cellular signaling pathways, such as BMI1, TRAIL, and Wnt. This review summarizes the results of our recent studies, particularly those involving natural products isolated from microbial resources, such as actinomycetes, obtained from soil samples collected primarily around Chiba, Japan.

Advances in targeting the WNT/β-catenin signaling pathway in cancer

WNT/β-catenin signaling orchestrates various physiological processes, including embryonic development, growth, tissue homeostasis, and regeneration. Abnormal WNT/β-catenin signaling is associated with various cancers and its inhibition has shown effective antitumor responses. In this review, we discuss the pathway, potential targets for the development of WNT/β-catenin inhibitors, available inhibitors, and their specific molecular interactions with the target proteins. We also discuss inhibitors that are in clinical trials and describe potential new avenues for therapeutically targeting the WNT/β-catenin pathway. Furthermore, we introduce emerging strategies, including artificial intelligence (AI)-assisted tools and technology-based actionable approaches, to translate WNT/β-catenin inhibitors to the clinic for cancer therapy.

Linderapyrone: A Wnt signal inhibitor isolated from Lindera umbellata

Linderapyrone, a Wnt signal inhibitor was isolated from the methanolic extract of the stems and twigs of Lindera umbellata together with epi-(-)-linderol A. Linderapyrone inhibited TCF/β-catenin transcriptional activity that was evaluated using cell-based TOPFlash luciferase assay system. To evaluate the structure-activity relationship and mechanism, we synthesized linderapyrone and its derivatives from piperitone. As the results of further bioassay for synthesized compounds, we found both of pyrone and monoterpene moieties were necessary for inhibitory effect. cDNA microarray analysis in a linderapyrone derivative treated human colorectal cancer cells showed that this compound downregulates Wnt signaling pathway. Moreover, we successes to synthesize the derivative of linderapyrone that has stronger inhibitory effect than linderapyrone and ICG-001 (positive control).

Hexane Extract of Chloranthus japonicus Increases Adipocyte Differentiation by Acting on Wnt/β-Catenin Signaling Pathway

Chloranthus japonicus has been heavily investigated for the treatment of various diseases. This paper attempts to show that Chloranthus japonicus can modulate adipocyte differentiation of preadipocytes. To establish this, we investigated the effects of Chloranthus japonicus extract in peroxisome proliferator-activated receptor γ (PPARγ) expression, adipogenesis, and the underlying molecular mechanisms in C3H10T1/2 and 3T3-L1 cells. Our data showed that Chloranthus japonicus methanol extract increased lipid accumulation and promoted adipocyte differentiation. Further studies on the fractionation with various solvents led to the identification of Chloranthus japonicus hexane extract (CJHE) as the most potent inducer of adipocyte differentiation. CJHE consistently increased lipid accumulation and adipocyte marker expression including Pparγ and it acted during the early stages of adipocyte differentiation. Mechanistic studies revealed that CJHE and a Wnt inhibitor similarly stimulated adipogenesis and were active in Wnt-selective reporter assays. The effects of CJHE were inhibited by Wnt3a protein treatment and were significantly blunted in β-catenin-silenced cells, further suggesting that CJHE acted on Wnt pathways to promote adipogenesis. We also showed that Chloranthus japonicus extracts generated from different plant parts similarly promoted adipocyte differentiation. These results identified Chloranthus japonicus as a pro-adipogenic natural product and suggest its potential use in metabolic syndrome.

Acacienone, a terpenoid-like natural product having an unprecedented C20 framework isolated from Acacia mangium leaves

A novel C20 natural product, acacienone (1), was isolated from the leaves of Acacia mangium collected in Bangladesh. The structure of compound 1 was elucidated by spectral studies and X-ray crystallographic analysis. Acacienone (1) possesses a terpenoid-related tetracyclic framework containing 20 carbons with biogenetically unusual structural features: (i) vicinal C1-branches at the C-3 and C-4 positions in the A ring, and (ii) a cyclopentenone D ring in an androsterone-like assembly, lacking a methyl group at the C-13 position.

Small Molecule Wnt Pathway Modulators from Natural Sources: History, State of the Art and Perspectives

The Wnt signaling is one of the major pathways known to regulate embryonic development, tissue renewal and regeneration in multicellular organisms. Dysregulations of the pathway are a common cause of several types of cancer and other diseases, such as osteoporosis and rheumatoid arthritis. This makes Wnt signaling an important therapeutic target. Small molecule activators and inhibitors of signaling pathways are important biomedical tools which allow one to harness signaling processes in the organism for therapeutic purposes in affordable and specific ways. Natural products are a well known source of biologically active small molecules with therapeutic potential. In this article, we provide an up-to-date overview of existing small molecule modulators of the Wnt pathway derived from natural products. In the first part of the review, we focus on Wnt pathway activators, which can be used for regenerative therapy in various tissues such as skin, bone, cartilage and the nervous system. The second part describes inhibitors of the pathway, which are desired agents for targeted therapies against different cancers. In each part, we pay specific attention to the mechanisms of action of the natural products, to the models on which they were investigated, and to the potential of different taxa to yield bioactive molecules capable of regulating the Wnt signaling.

New Insights about the Wnt/β-Catenin Signaling Pathway in Primary Bone Tumors and Their Microenvironment: A Promising Target to Develop Therapeutic Strategies?

Osteosarcoma and Ewing sarcoma are the most common malignant primary bone tumors mainly occurring in children, adolescents and young adults. Current standard therapy includes multidrug chemotherapy and/or radiation specifically for Ewing sarcoma, associated with tumor resection. However, patient survival has not evolved for the past decade and remains closely related to the response of tumor cells to chemotherapy, reaching around 75% at 5 years for patients with localized forms of osteosarcoma or Ewing sarcoma but less than 30% in metastatic diseases and patients resistant to initial chemotherapy. Despite Ewing sarcoma being characterized by specific EWSR1-ETS gene fusions resulting in oncogenic transcription factors, currently, no targeted therapy could be implemented. It seems even more difficult to develop a targeted therapeutic strategy in osteosarcoma which is characterized by high complexity and heterogeneity in genomic alterations. Nevertheless, the common point between these different bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Therefore, targeting different actors of the bone tumor microenvironment has been hypothesized to develop new therapeutic strategies. In this context, it is well known that the Wnt/β-catenin signaling pathway plays a key role in cancer development, including osteosarcoma and Ewing sarcoma as well as in bone remodeling. Moreover, recent studies highlight the implication of the Wnt/β-catenin pathway in angiogenesis and immuno-surveillance, two key mechanisms involved in metastatic dissemination. This review focuses on the role played by this signaling pathway in the development of primary bone tumors and the modulation of their specific microenvironment.