The Marine Natural Product Pseudopterosin Blocks Cytokine Release of Triple-Negative Breast Cancer and Monocytic Leukemia Cells by Inhibiting NF-κB Signaling

Approaches of marine compounds and relevant immune mediators in Autism Spectrum Disorder: Opportunities and challenges

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that affects social skills, language, communication, and behavioral skills, significantly impacting the individual's quality of life. Recently, numerous works have centered on the connections between the immune and central nervous systems and the influence of neuroinflammation on autism symptomatology. Marine natural products are considered as important alternative sources of different types of compounds, including polysaccharides, polyphenols, sterols, carotenoids, terpenoids and, alkaloids. These compounds present anti-inflammatory, neuroprotective and immunomodulatory activities, exhibiting a potential for the treatment of many diseases. Although many studies address the marine compounds in the modulation of inflammatory mediators, there is a gap regarding their use in the regulation of the immune system in ASD. Thus, this review aims to provide a better understanding regarding cytokines, chemokines, growth factors and immune responses in ASD, as well as the potential of bioactive marine compounds in the immune regulation in ASD. We expect that this review would contribute to the development of therapeutic alternatives for controlling immune mediators and inflammation in ASD.

Recent advances in anti-inflammatory active components and action mechanisms of natural medicines

Inflammation is a series of reactions caused by the body's resistance to external biological stimuli. Inflammation affects the occurrence and development of many diseases. Anti-inflammatory drugs have been used widely to treat inflammatory diseases, but long-term use can cause toxic side-effects and affect human functions. As immunomodulators with long-term conditioning effects and no drug residues, natural products are being investigated increasingly for the treatment of inflammatory diseases. In this review, we focus on the inflammatory process and cellular mechanisms in the development of diseases such as inflammatory bowel disease, atherosclerosis, and coronavirus disease-2019. Also, we focus on three signaling pathways (Nuclear factor-kappa B, p38 mitogen-activated protein kinase, Janus kinase/signal transducer and activator of transcription-3) to explain the anti-inflammatory effect of natural products. In addition, we also classified common natural products based on secondary metabolites and explained the association between current bidirectional prediction progress of natural product targets and inflammatory diseases.

Marine life as a source for breast cancer treatment: A comprehensive review

Breast cancer, one of the most significant tumors among all cancer cells, still has deficiencies for effective treatment. Moreover, substitute treatments employing natural products as bioactive metabolites has been seriously considered. The source of bioactive metabolites are not only the most numerous but also represent the richest source. A unique source is from the oceans or marine species which demonstrated intriguing chemical and biological diversity which represents an astonishing reserve for discovering novel anticancer drugs. Notably, marine sponges produce the largest amount of diverse bioactive peptides, alkaloids, terpenoids, polyketides along with many secondary metabolites whose potential is mostly therapeutic. In this review, our main focus is on the marine derived secondary metabolites which demonstrated cytotoxic effects towards numerous breast cancer cells and have been isolated from the marine sources such as marine sponges, cyanobacteria, fungi, algae, tunicates, actinomycetes, ascidians, and other sources of marine organisms.

Compounds from diverse natural origin against triple-negative breast cancer: A comprehensive review

Triple-negative breast cancer (TNBC) is caused due to the lack of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor 2 (HER2) expression. Triple-negative breast cancer is the most aggressive heterogeneous disease that is capable of producing different clones and mutations. Tumorigenesis in TNBC is caused due to the mutation or overexpression of tumor suppressor genes. It is also associated with mutations in the BRCA gene which is linked to hereditary breast cancer. In addition, PARP proteins and checkpoint proteins also play a crucial function in causing TNBC. Many cell signaling pathways are dysregulated in TNBC. Even though chemotherapy and immunotherapy are good options for TNBC treatment, the response rates are still low in general. Many phytochemicals that are derived from natural compounds have shown very good inhibitions for TNBC. Natural compounds have the great advantage of being less toxic, having lesser side effects, and being easily available. The secondary metabolites such as alkaloids, terpenoids, steroids, and flavonoids in natural products make them promising inhibitors of TNBC. Their compositions also offer vital insights into inhibitory action, which could lead to new cancer-fighting strategies. This review can help in understanding how naturally occurring substances and medicinal herbs decrease specific tumors and pave the way for the development of novel and extremely efficient antitumor therapies.

Phenanthroindolizidine Alkaloids Isolated from Tylophora ovata as Potent Inhibitors of Inflammation, Spheroid Growth, and Invasion of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), representing the most aggressive form of breast cancer with currently no targeted therapy available, is characterized by an inflammatory and hypoxic tumor microenvironment. To date, a broad spectrum of anti-tumor activities has been reported for phenanthroindolizidine alkaloids (PAs), however, their mode of action in TNBC remains elusive. Thus, we investigated six naturally occurring PAs extracted from the plant Tylophora ovata: O-methyltylophorinidine (1) and its five derivatives tylophorinidine (2), tylophoridicine E (3), 2-demethoxytylophorine (4), tylophoridicine D (5), and anhydrodehydrotylophorinidine (6). In comparison to natural (1) and for more-in depth studies, we also utilized a sample of synthetic O-methyltylophorinidine (1s). Our results indicate a remarkably effective blockade of nuclear factor kappa B (NFκB) within 2 h for compounds (1) and (1s) (IC50 = 17.1 ± 2.0 nM and 3.3 ± 0.2 nM) that is different from its effect on cell viability within 24 h (IC50 = 13.6 ± 0.4 nM and 4.2 ± 1 nM). Furthermore, NFκB inhibition data for the additional five analogues indicate a structure–activity relationship (SAR). Mechanistically, NFκB is significantly blocked through the stabilization of its inhibitor protein kappa B alpha (IκBα) under normoxic as well as hypoxic conditions. To better mimic the TNBC microenvironment in vitro, we established a 3D co-culture by combining the human TNBC cell line MDA-MB-231 with primary murine cancer-associated fibroblasts (CAF) and type I collagen. Compound (1) demonstrates superiority against the therapeutic gold standard paclitaxel by diminishing spheroid growth by 40% at 100 nM. The anti-proliferative effect of (1s) is distinct from paclitaxel in that it arrests the cell cycle at the G0/G1 state, thereby mediating a time-dependent delay in cell cycle progression. Furthermore, (1s) inhibited invasion of TNBC monoculture spheroids into a matrigel®-based environment at 10 nM. In conclusion, PAs serve as promising agents with presumably multiple target sites to combat inflammatory and hypoxia-driven cancer, such as TNBC, with a different mode of action than the currently applied chemotherapeutic drugs.

Modulation of TLR/NF-κB/NLRP Signaling by Bioactive Phytocompounds: A Promising Strategy to Augment Cancer Chemotherapy and Immunotherapy

Background

Tumors often progress to a more aggressive phenotype to resist drugs. Multiple dysregulated pathways are behind this tumor behavior which is known as cancer chemoresistance. Thus, there is an emerging need to discover pivotal signaling pathways involved in the resistance to chemotherapeutic agents and cancer immunotherapy. Reports indicate the critical role of the toll-like receptor (TLR)/nuclear factor-κB (NF-κB)/Nod-like receptor pyrin domain-containing (NLRP) pathway in cancer initiation, progression, and development. Therefore, targeting TLR/NF-κB/NLRP signaling is a promising strategy to augment cancer chemotherapy and immunotherapy and to combat chemoresistance. Considering the potential of phytochemicals in the regulation of multiple dysregulated pathways during cancer initiation, promotion, and progression, such compounds could be suitable candidates against cancer chemoresistance.

Objectives

This is the first comprehensive and systematic review regarding the role of phytochemicals in the mitigation of chemoresistance by regulating the TLR/NF-κB/NLRP signaling pathway in chemotherapy and immunotherapy.

Methods

A comprehensive and systematic review was designed based on Web of Science, PubMed, Scopus, and Cochrane electronic databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to include papers on TLR/NF-κB/NLRP and chemotherapy/immunotherapy/chemoresistance by phytochemicals.

Results

Phytochemicals are promising multi-targeting candidates against the TLR/NF-κB/NLRP signaling pathway and interconnected mediators. Employing phenolic compounds, alkaloids, terpenoids, and sulfur compounds could be a promising strategy for managing cancer chemoresistance through the modulation of the TLR/NF-κB/NLRP signaling pathway. Novel delivery systems of phytochemicals in cancer chemotherapy/immunotherapy are also highlighted.

Conclusion

Targeting TLR/NF-κB/NLRP signaling with bioactive phytocompounds reverses chemoresistance and improves the outcome for chemotherapy and immunotherapy in both preclinical and clinical stages.

Identification and Validation of CYBB, CD86, and C3AR1 as the Key Genes Related to Macrophage Infiltration of Gastric Cancer

Gastric cancer (GC) is rampant around the world. Most of the GC cases are detected in advanced stages with poor prognosis. The identification of marker genes for early diagnosis is of great significance. Studying the tumor environment is helpful to acknowledge the process of tumorigenesis, development, and metastasis. Twenty-two kinds of immune cells were calculated by CIBERSORT from Gene Expression Omnibus (GEO) database. Subsequently, higher infiltration of macrophages M0 was discovered in GC compared with normal tissues. WGCNA was utilized to construct the network and then identify key modules and genes related to macrophages in TCGA. Finally, 18 hub genes were verified. In the PPI bar chart, the top 3 genes were chosen as hub genes involved in most pathways. On the TIMER and THPA websites, it is verified that the expression levels of CYBB, CD86, and C3AR1 genes in tumor tissues were higher than those in normal tissues. These genes may work as biomarkers or targets for accurate diagnosis and treatment of GC in the future. Our findings may be a new strategy for the treatment of GC.

Creation of a synthesis-friendly inflammation-inducible promoter suitable for cell therapy

The development of 'smart' cell-based therapeutics requires cells that first recognize conditions consistent with disease (e.g. inflammation) and then subsequently release therapeutic proteins, thereby reducing potential toxicity from otherwise continuous expression. Promoters containing NF-κB response elements are often used as reporters of inflammation; however, endogenous promoters have crosstalk with other pathways, and current synthetic promoters have many exact sequence repeats of NF-κB response elements which make them both difficult to synthesize and inherently genetically unstable. Herein, a synthesis-friendly inflammation-inducible promoter (named SFNp) was created by the packing of 14 NF-κB response elements, which have no repeats >9 bp, followed by a minimal cytomegalovirus promoter. In stably expressing human embryonic kidney 293 cells, we assessed the ability of SFNp to inducibly transcribe genes for reporting expression, changing cell morphology, and performing cell fusion. These experiments represent simple milestones for potentially using SFNp in the development of cell-based therapeutics. As strongly repeated DNA can compromise the long-term stability of genetic circuits, new designs used in 'smart' cell therapy will become more reliant on synthesis-friendly components like SFNp.

Total Synthesis of (+)-Erogorgiaene and the Pseudopterosin A-F Aglycone via Enantioselective Cobalt-Catalyzed Hydrovinylation

Due to their pronounced bioactivity and limited availability from natural resources, metabolites of the soft coral Pseudopterogorgia elisabethae, such as erogorgiaene and the pseudopterosines, represent important target molecules for chemical synthesis. We have now developed a particularly short and efficient route towards these marine diterpenes exploiting an operationally convenient enantioselective cobalt-catalyzed hydrovinylation as the chirogenic step. Other noteworthy C-C bond forming transformations include diastereoselective Lewis acid-mediated cyclizations, a Suzuki coupling and a carbonyl ene reaction. Starting from 4-methyl-styrene the anti-tubercular agent (+)-erogorgiaene (>98 % ee) was prepared in only 7 steps with 46 % overall yield. In addition, the synthesis of the pseudopterosin A aglycone was achieved in 12 steps with 30 % overall yield and, surprisingly, was found to exhibit a similar anti-inflammatory activity (inhibition of LPS-induced NF-κB activation) as a natural mixture of pseudopterosins A-D or iso-pseudopterosin A, prepared by β-D-xylosylation of the synthetic aglycone.

Promising Activities of Marine Natural Products against Hematopoietic Malignancies

According to the WHO classification of tumors, more than 150 typologies of hematopoietic and lymphoid tumors exist, and most of them remain incurable diseases that require innovative approaches to improve therapeutic outcome and avoid side effects. Marine organisms represent a reservoir of novel bioactive metabolites, but they are still less studied compared to their terrestrial counterparts. This review is focused on marine natural products with anticancer activity against hematological tumors, highlighting recent advances and possible perspectives. Until now, there are five commercially available marine-derived compounds for the treatment of various hematopoietic cancers (e.g., leukemia and lymphoma), two molecules in clinical trials, and series of compounds and/or extracts from marine micro- and macroorganisms which have shown promising properties. In addition, the mechanisms of action of several active compounds and extracts are still unknown and require further study. The continuous upgrading of omics technologies has also allowed identifying enzymes with possible bioactivity (e.g., l-asparaginase is currently used for the treatment of leukemia) or the enzymes involved in the synthesis of bioactive secondary metabolites which can be the target of heterologous expression and genetic engineering.

The Natural Products and Extracts: Anti-Triple-Negative Breast Cancer in Vitro

Triple-negative breast cancer (TNBC) makes up 15 % to 20 % of all breast cancer (BC) cases, and represents one of the most challenging malignancies to treat. For many years, chemotherapy has been the main treatment option for TNBC. Natural products isolated from marine organisms and terrestrial organisms with great structural diversity and high biochemical specificity form a compound library for the assessment and discovery of new drugs. In this review, we mainly focused on natural compounds and extracts (from marine and terrestrial environments) with strong anti-TNBC activities (IC₅₀ <100 μM) and their possible mechanisms reported in the past six years (2015-2021).

Understanding the function of the tumor microenvironment, and compounds from marine organisms for breast cancer therapy

The pathology and physiology of breast cancer (BC), including metastasis, and drug resistance, is driven by multiple signaling pathways in the tumor microenvironment (TME), which hamper antitumor immunity. Recently, long non-coding RNAs have been reported to mediate pathophysiological develop-ments such as metastasis as well as immune suppression within the TME. Given the complex biology of BC, novel personalized therapeutic strategies that address its diverse pathophysiologies are needed to improve clinical outcomes. In this review, we describe the advances in the biology of breast neoplasia, including cellular and molecular biology, heterogeneity, and TME. We review the role of novel molecules such as long non-coding RNAs in the pathophysiology of BC. Finally, we provide an up-to-date overview of anticancer compounds extracted from marine microorganisms, crustaceans, and fishes and their synergistic effects in combination with other anticancer drugs. Marine compounds are a new discipline of research in BC and offer a wide range of anti-cancer effects that could be harnessed to target the various pathways involved in BC development, thus assisting current therapeutic regimens.

Monotropein alleviates H2O2‑induced inflammation, oxidative stress and apoptosis via NF‑κB/AP‑1 signaling

Aging is a major risk factor in cardiovascular disease (CVD). Oxidative stress and inflammation are involved in the pathogenesis of CVD, and are closely associated with senescent vascular endothelial cells. Monotropein (Mtp) exerts various bioactive roles, including anti‑inflammatory and antioxidative effects. The aim of the present study was to investigate the function of Mtp in senescent endothelial cells. An MTT assay was performed to evaluate the influence of Mtp on H2O2‑stimulated human umbilical vein endothelial cells (HUVECs). Senescent cells were assessed by determining the expression of senescence‑associated β‑galactosidase, high mobility group AT‑hook 1 and DNA damage marker γ‑H2A.X variant histone. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH‑Px) and proinflammatory cytokine concentrations were estimated using assay kits to evaluate the levels of oxidative stress and inflammation in HUVECs. The TUNEL assay was performed to identify apoptotic cells. Furthermore, the expression levels of endothelial cell adhesion factors, NF‑κB, activator protein‑1 (AP‑1) and apoptotic proteins were determined via western blotting. Mtp enhanced HUVEC viability following H2O2 stimulation. H2O2‑mediated increases in MDA, proinflammatory cytokine and endothelial cell adhesion factor levels were decreased by Mtp treatment, whereas Mtp reversed H2O2‑mediated downregulation of SOD and GSH‑Px activity. Furthermore, Mtp inhibited cell apoptosis, NF‑κB activation and AP‑1 expression in H2O2‑stimulated HUVECs; however, NF‑κB activator counteracted the anti‑inflammatory, antioxidative and antiapoptotic effects of Mtp. The present study indicated that Mtp ameliorated H2O2‑induced inflammation and oxidative stress potentially by regulating NF‑κB/AP‑1.

Pseudopterosin and O-Methyltylophorinidine Suppress Cell Growth in a 3D Spheroid Co-Culture Model of Pancreatic Ductal Adenocarcinoma

Current therapies for treating pancreatic ductal adenocarcinoma (PDAC) are largely ineffective, with the desmoplastic environment established within these tumors being considered a central issue. We established a 3D spheroid co-culture in vitro model using a PDAC cell line (either PANC-1 or Capan-2), combined with stellate cells freshly isolated from pancreatic tumors (PSC) or hepatic lesions (HSC), and human type I collagen to analyze the efficiency of the chemotherapeutic gemcitabine (GEM) as well as two novel drug candidates derived from natural products: pseudopterosin (PsA-D) and O-methyltylophorinidine (TYLO). Traditional 2D in vitro testing of these agents for cytotoxicity on PANC-1 demonstrated IC₅₀ values of 4.6 (±0.47) nM, 34.02 (±1.35) µM, and 1.99 (±0.13) µM for Tylo, PsA-D, and GEM, respectively; these values were comparable for Capan-2: 5.58 (±1.74) nM, 33.94 (±1.02) µM, and 0.41 (±0.06) µM for Tylo, PsA-D, and GEM, respectively. Importantly, by assessing the extent of viable cells within 3D co-culture spheroids of PANC-1 with PSC or HSC, we could demonstrate a significant lack of efficacy for GEM, while TYLO remained active and PsA-D showed slightly reduced efficacy: GEM in PANC-1/PSC (IC₅₀ = >100 µM) or PANC-1/HSC (IC₅₀ = >100 µM) spheroids, TYLO in PANC-1/PSC (IC₅₀ = 3.57 ± 1.30 nM) or PANC-1/HSC (IC₅₀ = 6.39 ± 2.28 nM) spheroids, and to PsA-D in PANC-1/PSC (IC₅₀ = 54.42 ± 12.79 µM) or PANC-1/HSC (IC₅₀ = 51.75 ± 0.60 µM). Microscopic 3D rendering supported these cytotoxicity outcomes, showing little or no morphological spheroid structure change during this period of rapid cell death. Our results support the use of this 3D spheroid co-culture in vitro model having a desmoplastic microenvironment for the identification of possible novel chemotherapeutic drug candidates for PDAC, such as TYLO and PsA-D.

Sphaerococcus coronopifolius bromoterpenes as potential cancer stem cell-targeting agents

Cancer is one of the major threats to human health and, due to distinct factors, it is expected that its incidence will increase in the next decades leading to an urgent need of new anticancer drugs development. Ongoing experimental and clinical observations propose that cancer cells with stem-like properties (CSCs) are involved on the development of lung cancer chemoresistance. As tumour growth and metastasis can be controlled by tumour-associated stromal cells, the main goal of this study was to access the antitumor potential of five bromoterpenes isolated from Sphaerococcus coronopifolius red alga to target CSCs originated in a co-culture system of fibroblast and lung malignant cells. Cytotoxicity of compounds (10-500 μM; 72 h) was evaluated on monocultures of several malignant and non-malignant cells lines (HBF, BEAS-2B, RenG2, SC-DRenG2) and the effects estimated by MTT assay. Co-cultures of non-malignant human bronchial fibroblasts (HBF) and malignant human bronchial epithelial cells (RenG2) were implemented and the compounds ability to selectively kill CSCs was evaluated by sphere forming assay. The interleucine-6 (IL-6) levels were also determined as cytokine is crucial for CSCs. Regarding the monocultures results bromosphaerol selectively eliminated the malignant cells. Both 12S-hydroxy-bromosphaerol and 12R-hydroxy-bromosphaerol steroisomers were cytotoxic towards non-malignant bronchial BEAS-2B cell line, IC₅₀ of 4.29 and 4.30 μM respectively. However, none of the steroisomers induced damage in the HBFs. As to the co-cultures, 12R-hydroxy-bromosphaerol revealed the highest cytotoxicity and ability to abrogate the malignant stem cells; however its effects were IL-6 independent. The results presented here are the first evidence of the potential of these bromoterpenes to abrogate CSCs opening new research opportunities. The 12R-hydroxy-bromosphaerol revealed to be the most promising compound to be test in more complex living models.

Concise Formal Synthesis of the Pseudopterosins via Anionic Oxy-Cope/Transannular Michael Addition Cascade

An anionic oxy-Cope/transannular Michael addition cascade converts a spirocyclic architecture-readily available by Diels-Alder cycloaddition-into the hydrophenalene carbon skeleton of the pseudopterosin aglycones. Oxidation of the resulting cyclohexenone ring to the phenol that is characteristic of the targets completes a short formal synthesis.

Didymellanosine, a new decahydrofluorene analogue, and ascolactone C from Didymella sp. IEA-3B.1, an endophyte of Terminalia catappa

Didymellanosine (1), the first analogue of the decahydrofluorene-class of natural products bearing a 13-membered macrocyclic alkaloid conjugated with adenosine, and a new benzolactone derivative, ascolactone C (4) along with eight known compounds (2, 3, 5–10), were isolated from a solid rice fermentation of the endophytic fungus Didymella sp. IEA-3B.1 derived from the host plant Terminalia catappa. In addition, ascochitamine (11) was obtained when (NH₄)₂SO₄ was added to rice medium and is reported here for the first time as a natural product. Didymellanosine (1) displayed strong activity against the murine lymphoma cell line L5178Y, Burkitt's lymphoma B cells (Ramos) and adult lymphoblastic leukemia T cells (Jurkat J16), with IC₅₀ values of 2.0, 3.3 and 4.4 µM, respectively. When subjected to a NFκB inhibition assay, didymellanosine (1) moderately blocked NFκB activation in the triple-negative breast cancer cell line MDA-MB 231. In an antimicrobial assay, ascomylactam C (3) was the most active compound when tested against a panel of Gram-positive bacteria including drug-resistant strains with MICs of 3.1–6.3 µM, while 1 revealed weaker activity. Interestingly, both compounds were also found active against Gram-negative Acinetobacter baumannii with MICs of 3.1 µM, in the presence of a sublethal concentration (0.1 µM) of colistin.

An unusual decahydrofluorene-class alkaloid from Didymella sp. exhibited NFκB inhibitory and antimicrobial activities.

Marine anticancer drugs and their relevant targets: a treasure from the ocean

Marine organisms comprising animals and plants are wealthiest sources of bioactive compounds possessing various pharmacological properties specifically: free radical scavenging, antitumor, antimicrobial, analgesic, neuroprotective and immunomodulatory. Marine drugs provide an alternative source to meet the demand of effective, safe and low-cost drugs that are rising with the continuously growing world population. Cancer is one of the leading reasons of mortality in western nations in contrast to communicable diseases of developing nations. In spite of outstanding developments in cancer therapy in past three decades, there is still an insistent necessity for innovative drugs in the area of cancer biology, especially in the unexplored area of marine anticancer compounds. However, recent technological innovations in structure revelation, synthetic creation of new compounds and biological assays have made possible the isolation and clinical assessment of innumerable unique anticancer compounds from marine environment. This review provides an insight into the anticancer research so far conducted in the area of the marine natural products/synthetic derivatives, their possible molecular targets and the current challenges in the drug development. Graphical abstract.

Marine natural products

Covering: January to December 2017This review covers the literature published in 2017 for marine natural products (MNPs), with 740 citations (723 for the period January to December 2017) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1490 in 477 papers for 2017), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. Geographic distributions of MNPs at a phylogenetic level are reported.

Azaphilone Derivatives from the Fungus Coniella fragariae Inhibit NF-κB Activation and Reduce Tumor Cell Migration

Seven new azaphilones, coniellins A-G (1-7), were obtained from the fungus Coniella fragariae that had been isolated from goose dung. Their structures were elucidated by analysis of 1D and 2D NMR as well as HRESIMS data. TDDFT-ECD calculation was used to determine the absolute configuration of 1, while Mosher's method was applied to determine the absolute configuration of 5. While displaying only moderate cytotoxicity, compound 1 exhibited significant inhibition of NF-κB activation in the triple negative breast cancer cell line MDA-MB-231 with an IC₅₀ value of 4.4 μM. Moreover, compounds 1, 4, and 5 clearly reduced tumor cell migration. Compound 1 was the most active derivative tested in this assay and displayed 60% inhibition of tumor cell migration at a dose of 5 μM and 98% inhibition at 10 μM after 24 h.

Pseudopterosin Inhibits Proliferation and 3D Invasion in Triple-Negative Breast Cancer by Agonizing Glucocorticoid Receptor Alpha

Pseudopterosin, produced by the sea whip of the genus Antillogorgia, possesses a variety of promising biological activities, including potent anti-inflammatory effects. However, few studies examined pseudopterosin in the treatment of cancer cells and, to our knowledge, the ability to inhibit triple-negative breast cancer (TNBC) proliferation or invasion has not been explored. Thus, we evaluated the as-yet unknown mechanism of action of pseudopterosin: Pseudopterosin was able to inhibit proliferation of TNBC. Interestingly, analyzing breast cancer cell proliferation after knocking down glucocorticoid receptor α (GRα) revealed that the antiproliferative effects of pseudopterosin were significantly inhibited when GRα expression was reduced. Furthermore, pseudopterosin inhibited the invasion of MDA-MB-231 3D tumor spheroids embedded in an extracellular-like matrix. Remarkably, the knockdown of GRα in 3D tumor spheroids revealed increased ability of cells to invade the surrounding matrix. In a coculture, encompassing peripheral blood mononuclear cells (PBMC) and MDA-MB-231 cells, and the production of interleukin 6 (IL-6) and interleukin 8 (IL-8) significantly increased compared to a monoculture. Notably, pseudopterosin indicated to block cytokine elevation, representing key players in tumor progression in the coculture. Thus, our results reveal pseudopterosin treatment as a potential novel approach in TNBC therapy.