Identification of Hirsutine as an anti-metastatic phytochemical by targeting NF-κB activation

Advanced researches of traditional uses, phytochemistry, pharmacology, and toxicology of medical Uncariae Ramulus Cum Uncis

ETHNOPHARMACOLOGICAL RELEVANCE

Medical Uncariae Ramulus Cum Uncis consists of Uncaria rhynchophylla (Miq.) Miq. ex Havil, Uncaria macrophylla Wall, Uncaria sinensis (Oliv.) Havil, Uncaria hirsuta Havil, and Uncaria sessilifructus Roxb, which belongs to the species widely used in the genus Uncaria. These species resource widely distributed in China and abroad, and the hook-bearing stem is the primary constituent enrichment site. There are many different forms and architectures of chemicals, depending on the extraction site. Traditional remedies employing URCU had been used widely in antiquity and were first compiled in renowned ancient masterpiece 'Mingyi Bielu ()' written by Hongjing Tao. In modern pharmacological studies, both the total extracts and the phytoconstituents isolated from URCU have been shown to have neuroprotective, antioxidant, anti-inflammatory, anticancer, antibacterial, and autophagy-enhancer properties.

AIM OF THE STUDY

This review concentrates on the traditional uses, phytochemistry, pharmacology, toxicology, and nanomaterials studies of URCU, with a perspective to assist with further research and advance.

MATERIAL AND METHODS

The Chinese and English literature studies of this review are based on these database searches including Science Direct, CNKI, Wiley online library, Spring Link, Web of Science, PubMed, Medalink, Google scholar, Elsevier, ACS Publications, iPlant, Missouri Botanical Garden, Plant of the World Online. The pertinent data on URCU was gathered.

RESULTS

Based on the examination of the genus Uncaria, 107 newly marked chemical compositions have been identified from URCU from 2015 to present, including alkaloids, terpenoids, flavonoids, steroids, and others. Pharmacological studies have demonstrated that URCU has a variety of benefits in diseases such as neurodegenerative diseases, cancer, cardiovascular diseases, diabetes, and migraine, due to its neuroprotective, anti-inflammatory, antioxidant, anti-tumor, anti-bacterial and anti-viral properties. According to metabolic and toxicological studies, the dosage, frequency, and interactions of the drugs that occur in vivo are of great significance for determining whether the organic bodies can perform efficacy or produce toxicity. The research on URCU-mediated nanomaterials is expanding and increasing in order to address the inadequacies of conventional Chinese medicine. The alkaloids in URCU have the capability to self-assemble with other classes of components in addition to being biologically active.

CONCLUSION

URCU plants are widely distributed, abundant in chemical constituents, and widely used in both traditional and modern medicine for a variety of pharmacological effects. The utilization of herbal medicines can be raised by assessing the pharmacological distinctions among several species within the same genus and may accelerate the modernization of traditional Chinese medicine. Controlling the concentration of drug administration, monitoring metabolic markers, and inventing novel nanotechnologies are effective strategies for synergistic influence and detoxification to alleviate the main obstacles that toxicity, low bioavailability, and poor permeability. This review can assist further research and advances.

Pharmacological potential of micheliolide: A focus on anti-inflammatory and anticancer activities

Micheliolide (MCL) is a chief constituent of plants such as Magnolia grandiflora L., Michelia compressa (Maxim.) Sarg. and Michelia champaca L. It is known to exhibit significant anticancer activity by various scientific investigations. This review aims to emphasize the anticancer and antiinflammatory activities of MCL. In this review, we summarized the published data in peer-reviewed manuscripts published in English. Our search was based on the following scientific search engines and databases: Scopus, Google Scholar, ScienceDirect, Springer, PubMed, and SciFinder, MCL possesses a broad spectrum of medicinal properties like other sesquiterpene lactones. The anticancer activity of this compound may be attributed to the modulation of several signaling cascades (PI3K/Akt and NF-κB pathways). It also induces apoptosis by arresting the cell cycle at the G1/G0 phase, S phase, and G2/M phase in many cancer cell lines. Very little data is available on its modulatory action on other signaling cascades like MAPK, STAT3, Wnt, TGFβ, Notch, EGFR, etc. This compound can be potentiated as a novel anticancer drug after thorough investigations in vitro, in vivo, and in silico-based studies.

Hirsutine, an Emerging Natural Product with Promising Therapeutic Benefits: A Systematic Review

Fruits and vegetables are used not only for nutritional purposes but also as therapeutics to treat various diseases and ailments. These food items are prominent sources of phytochemicals that exhibit chemopreventive and therapeutic effects against several diseases. Hirsutine (HSN) is a naturally occurring indole alkaloid found in various Uncaria species and has a multitude of therapeutic benefits. It is found in foodstuffs such as fish, seafood, meat, poultry, dairy, and some grain products among other things. In addition, it is present in fruits and vegetables including corn, cauliflower, mushrooms, potatoes, bamboo shoots, bananas, cantaloupe, and citrus fruits. The primary emphasis of this study is to summarize the pharmacological activities and the underlying mechanisms of HSN against different diseases, as well as the biopharmaceutical features. For this, data were collected (up to date as of 1 July 2023) from various reliable and authentic literature by searching different academic search engines, including PubMed, Springer Link, Scopus, Wiley Online, Web of Science, ScienceDirect, and Google Scholar. Findings indicated that HSN exerts several effects in various preclinical and pharmacological experimental systems. It exhibits anti-inflammatory, antiviral, anti-diabetic, and antioxidant activities with beneficial effects in neurological and cardiovascular diseases. Our findings also indicate that HSN exerts promising anticancer potentials via several molecular mechanisms, including apoptotic cell death, induction of oxidative stress, cytotoxic effect, anti-proliferative effect, genotoxic effect, and inhibition of cancer cell migration and invasion against various cancers such as lung, breast, and antitumor effects in human T-cell leukemia. Taken all together, findings from this study show that HSN can be a promising therapeutic agent to treat various diseases including cancer.

Targeting Cell Signaling Pathways in Lung Cancer by Bioactive Phytocompounds

Lung cancer is a heterogeneous group of malignancies with high incidence worldwide. It is the most frequently occurring cancer in men and the second most common in women. Due to its frequent diagnosis and variable response to treatment, lung cancer was reported as the top cause of cancer-related deaths worldwide in 2020. Many aberrant signaling cascades are implicated in the pathogenesis of lung cancer, including those involved in apoptosis (B cell lymphoma protein, Bcl-2-associated X protein, first apoptosis signal ligand), growth inhibition (tumor suppressor protein or gene and serine/threonine kinase 11), and growth promotion (epidermal growth factor receptor/proto-oncogenes/phosphatidylinositol-3 kinase). Accordingly, these pathways and their signaling molecules have become promising targets for chemopreventive and chemotherapeutic agents. Recent research provides compelling evidence for the use of plant-based compounds, known collectively as phytochemicals, as anticancer agents. This review discusses major contributing signaling pathways involved in the pathophysiology of lung cancer, as well as currently available treatments and prospective drug candidates. The anticancer potential of naturally occurring bioactive compounds in the context of lung cancer is also discussed, with critical analysis of their mechanistic actions presented by preclinical and clinical studies.

In Vitro Cytotoxicity and Spectral Analysis-Based Phytochemical Profiling of Methanol Extract of Barleria hochstetteri, and Molecular Mechanisms Underlying Its Apoptosis-Inducing Effect on Breast and Lung Cancer Cell Lines

The objectives of this research were to carry out GC–MS and LC–MS-based phytochemical profiling of Barleria hochstetteri, as well as flow cytometry-based mechanistic investigations of the cytotoxic effect of its extracts against breast and lung cancer cell lines. This preclinical in vitro study was carried out in Saudi Arabia and India, from 11 August to 15 January 2022. Barleria hochstetteri was sequentially extracted using the Soxhlet extraction technique. Utilizing LC–MS and GC–MS methods, the phytochemical profiling was performed. Additionally, the total phenolic compounds and flavonoids were quantified in the plant extract using spectrophotometric techniques. In this study, we first examined the cytotoxicity of the plant extract on non-malignant L929 cells and on the carcinogenic MCF-7 and A549 cell lines. Then, we studied the underlying molecular pathways by means of Anti-Bcl-2, caspase-3, and DNA fragmentation (TUNEL) assays, using flow cytometry. The results revealed phenolic compounds and flavonoids to be the two major components in the methanolic extract of B. hochstetteri, with concentrations of 3210 µg GAE/g dwt and 1863 µg QE/g dwt, respectively. Results from GC–MS and LC–MS analyses revealed the presence of bioactive phytochemicals with known cytotoxicity. From the MTT assay on cell viability, the IC50 of the methanol extract for the MCF-7 and A549 cell lines were 219.67 and 144.30 µg/mL, respectively. With IC50 values of 324.24 and 266.66 µg/mL, respectively, the aqueous and methanol extracts were less toxic when tested against the non-cancerous L929 cell line. The extract caused early and late apoptosis in the tested breast and lung cancer cells by activating caspase-3 and inhibiting Bcl-2 protein, and it also caused cell death via DNA damage, based on flow cytometric and molecular marker analyses. These findings indicate that the methanol extract of B. hochstetteri was cytotoxic on breast cancer and lung cancer cell lines. To uncover cancer-fighting chemicals, there is a need for further research on B. hochstetteri, as it is a promising source of anti-cancer chemotherapeutic drugs.

Breast Cancer: A Global Concern, Diagnostic and Therapeutic Perspectives, Mechanistic Targets in Drug Development

Cancer is a complex multifactorial process, unchecked and abrupt division, and cell growth—conventional chemotherapy, along with radiotherapy, is used to treat breast cancer. Due to reduce efficacy and less survival rate, there is a particular need for the discovery of new active anticancer agents. Natural resources such as terrestrial/marine plants or organisms are a promising source for the generation of new therapeutics with improving efficacy. The screening of natural plant extracts and fractions, isolations of phytochemicals, and mechanistic study of those potential compounds play a remarkable role in the development of new therapeutic drugs with increased efficacy. Cancer is a multistage disease with complex signaling cascades. The initial study of screening whole extracts or fractions and later the isolation of secondary compounds and their mechanism of action study gives a clue of potential therapeutic agents for future drug development. The phytochemicals present in extracts/fractions produce remarkable effects due to synergistically targeting multiple signals. In this review, the molecular targets of extracts/ fractions and isolated compounds highlighted. The therapeutic agent's mechanistic targets in drug development focused involves; i) Induction of Apoptosis, ii) modulating cell cycle arrest, iii) Inhibition or suppression of invasion and metastasis and iv) various other pro-survival signaling pathways. The phytochemicals and their modified analogs identified as future potential candidates for anticancer chemotherapy.

Role of Phytonutrients in Nutrigenetics and Nutrigenomics Perspective in Curing Breast Cancer

Breast cancer (BC) is one of the most common type of cancer and an important contributor to female mortality. Several genes and epigenetic modifications are involved in the development and progression of BC. Research in phytochemistry, nutrigenomics, and nutrigenetics has provided strong evidence that certain phytonutrients are able to modulate gene expression at transcriptional and post-transcriptional levels. Such phytonutrients may also be beneficial to prevent and treat BC. In this review, we will focus on the nutrigenomic effects of various phytochemicals including polyphenols, phytosterols, terpenoids, alkaloids, and other compounds from different sources. Overall, these phytonutrients are found to inhibit BC cell proliferation, differentiation, invasion, metastasis, angiogenesis, and induce apoptotic cell death by targeting various molecular pathways. They also alter epigenetic mechanisms and enhance the chemosensitivity and radiosensitivity of cancer cells. Such phytochemicals may be used for the effective management of BC patients in the clinical setting in the future. The present article aims to summarize the specific molecular pathways involved in the genetic effects of phytochemicals in BC.

Synthetic E-guggulsterone derivative GSD-1 inhibits NF-κB signaling and suppresses the metastatic potential of breast cancer cells

Guggulsterone (GS) [4,17(20)-pregnadiene-3,16-dione], is the main active phytosterol constituent in guggul, the gum resin of Commiphora wightii (Arnott.) Bhand./Commiphora mukul Engl. tree, and is known for its medicinal effects. In this study, we report that GSD-1, a structurally-related synthetic GS derivative, strongly inhibits NF-κB activation induced by TNF-α. GSD-1 prevented the nuclear translocation of p65 through the blockade of IκBα degradation and p65 phosphorylation, and further inhibited the activation of upstream kinases, including transforming growth factor-β activated kinase 1 (TAK1), IκB kinase (IKK) α, and IKKβ. Furthermore, GSD-1 inhibited the cell-intrinsic activation of NF-κB, and exerted its direct anti-cancer and anti-metastatic effects in both murine and human breast cancer cell lines. This study demonstrated GSD-1 to be an attractive compound to target NF-κB activation that has potential for treating breast cancer growth and metastasis.

Identification of Ophiocordyceps gracilioides by Its Anti-tumor Effects through Targeting the NFκB-STAT3-IL-6 Inflammatory Pathway

Although more than 400 species of Cordyceps s.l. have been identified, most have not been well explored regarding their potential for medicinal use. In this study, the profiles of constituents of ten different species of Ophiocordyceps, which is an unexplored species of Cordyceps, were analyzed and their anti-tumor effects were further examined. Although all Ophiocordyceps samples exhibited similar peak patterns, Ophiocordyceps gracilioides (O. grac) had a distinct constituent profile from the other samples. Furthermore, O. grac was the most active in suppressing the transcriptional activities of both nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription (STAT)3, and the production of interleukin (IL)-6 from breast cancer cells. This study demonstrated that O. grac is a relatively unexplored Cordyceps s.l. that may have medicinal potential to inhibit the NFκB-STAT3-IL-6 inflammatory pathway in cancer.

Anti-metastatic effects of ergosterol peroxide from the entomopathogenic fungus Ophiocordyceps gracilioides on 4T1 breast cancer cells

Ophiocordyceps gracilioides is an entomoparasitic ascomycetes whose bioactivity has not been examined in detail. In this study, we identified the bioactive compounds ergosterol peroxide (EPO) and ergosterol (ERG) from the MeOH extract of O. gracilioides mycelia related to its anti-cancer effects by targeting the Nuclear Factor kappa B (NF-ĸB)/Signal Transducer and Activator of Transcription 3 (STAT3) inflammatory pathways. Using gene-reporter assays, we demonstrated that EPO markedly inhibits both NF-ĸB and STAT3 activity in 4T1 cells, whereas ERG had limited effect. Consistent with their effects on NF-ĸB and STAT3 activity, EPO, but not ERG, exerted anti-proliferative effects on 4T1 cells. Furthermore, EPO significant inhibited both the migration and invasion of 4T1 cells in vitro, and pre-treatment of 4T1 cells with EPO significantly inhibited the formation of experimental lung metastases in vivo. Collectively, we demonstrated that ERG and EPO can be isolated from O. gracilioides mycelia, and further identified EPO as an active constituent of its anti-metastatic effects through the inhibition of NF-ĸB and STAT3 inflammatory pathways in 4T1 breast cancer cells.

Inhibitory effect and mechanism of action (MOA) of hirsutine on the proliferation of T-cell leukemia Jurkat clone E6-1 cells

Background

The bark of Uncaria rhynchophylla has been traditionally used to treat convulsion, bleeding, hypertension, auto-immune conditions, cancer, and other diseases. The main focus of this research is done for the purpose of exploring the antitumor activity and mechanism of action (MOA) for hirsutine isolated from U. rhynchophylla.

Methods

Jurkat clone E6-1 cells were treated using 10, 25 and 50 μM for 48 h. Inhibition of cell proliferation due to hirsutine treatment was evaluated by CCK8 assay. Flow cytometry was applied to ascertain Jurkat cell cycle progression and apoptosis after treatment with 10, 25 and 50 μM hirsutine for 48 h. The expression and level of the apoptosis-related genes and proteins was analyzed by Real-time Quantitative polymerase chain reaction (qPCR) and Western blotting method, respectively.

Results

CCK8 analyses revealed that hirsutine could significantly inhibit the proliferation of Jurkat clone E6-1 cells, in a concentration and time-dependent fashion. Flow cytometry assays revealed that hirsutine could drive apoptotic death and G0/G1 phase arrest in Jurkat cells. Apoptotic cells frequencies were 4.99 ± 0.51%, 13.69 ± 2.00% and 40.21 ± 15.19%, and respective cell cycle arrest in G0/G1 accounted for 34.85 ± 1.81%, 42.83 ± 0.70% and 49.12 ± 4.07%. Simultaneously, compared with the control group, Western blot assays indicated that the up-regulation of pro-apoptotic Bax, cleaved-caspase3, cleaved-caspase9 and Cyto c proteins, as well as the down-regulation of Bcl-2 protein which guards against cell death, might be correlated with cell death induction and inhibition of cell proliferation. QPCR analyses indicated that hirsutine could diminish BCL2 expression and, at the same time, improve Bax, caspase-3 and caspase-9 mRNA levels, thus reiterating a putative correlation of hirsutine treatment in vitro with apoptosis induction and inhibition of cell proliferation (p-value < 0.05). Excessive hirsutine damages the ultrastructure in mitochondria, leading to the release of Cyt c from the mitochondria to cytoplasm in Jurkat clone E6-1 cells, thereby inducing the activated caspase cascade apoptosis process through a mitochondria-mediated pathway.

Conclusion

An important bioactive constituent-hirsutine-appears to have antitumor effects in human T-cell leukemia, thus enlightening the use of phytomedicines as a novel source for tumor therapy. It is speculated that hirsutine may induce apoptosis of Jurkat Clone E6-1 cells through the mitochondrial apoptotic pathway.

Anti-Inflammatory Activity of Miodesin™: Modulation of Inflammatory Markers and Epigenetic Evidence

PURPOSE

To investigate the effects of a combined herbal medicine Miodesin™ on the inflammatory response of key cells involved in the acute and chronic inflammatory processes as well as the possible epigenetic involvement.

METHODS

After the establishment of the IC50 dose, the chondrocyte, keratinocyte, and macrophage cell lines were pretreated for 2 hours with Miodesin™ (200 μg/mL) and stimulated with LPS (1 μg/mL) for 24 hours. The supernatant was used to measure the levels of cytokines (IL-1β, IL-6, IL-8, and TNF-α) and chemokines (CCL2, CCL3, and CCL5), and the cells were used to extract the mRNA for the transcription factor (NF-κβ), inflammatory enzymes (COX-1, COX-2, PLA2, and iNOS), and chemokines (CCL2, CCL3, and CCL5).

RESULTS

Miodesin™ inhibited the release of LPS-induced cytokines (IL-1β, IL-6, IL-8, and TNF-α; p < 0.01) and chemokines (CCL2, CCL3, and CCL5; p < 0.01) and the expression of the transcription factor (NF-κβ; p < 0.01), inflammatory enzymes (COX-1, COX-2, PLA2, iNOS; p < 0.01), and chemokines (CCL2, CCL3, and CCL5; p < 0.01). In addition, the evaluation of epigenetic mechanism revealed that Miodesin™ did not induce changes in DNA methylation, assuring the genetic safeness of the compound in terms of the inflammatory response.

CONCLUSIONS

Miodesin™ presents anti-inflammatory properties, inhibiting hyperactivation of chondrocytes, keratinocytes, and macrophages, involving epigenetics in such effects.

Curcumol: From Plant Roots to Cancer Roots

Natural products, an infinite treasure of bioactive scaffolds, have provided an excellent reservoir for the discovery of drugs since millennium. These naturally occurring, biologically active and therapeutically effective chemical entities have emerged as novel paradigm for the prevention of various diseases. This review aims to give an update on the sources as well as pharmacological profile of curcumol, a pharmacologically active sesquiterpenoid, which is an imperative bioactive constituent of several plants mainly from genus Curcuma. Curcumol has potential to fight against cancer, oxidative stress, neurodegeneration, microbial infections, and inflammation. Curcumol has been documented as potent inducer of apoptosis in numerous cancer cells via targeting key signaling pathways as MAPK/ERK, PI3K/Akt and NF-κB which are generally deregulated in several cancers. The reported data reveals multitarget activity of curcumol in cancer treatment suggesting its importance as anticancer drug in future. It is speculated that curcumol may provide an excellent opportunity for the cure of cancer but further investigations on mechanism of its action and preclinical trials are still mandatory to further validate the potential of this natural cancer killer in anticancer therapies.

Hirsutine induces mPTP-dependent apoptosis through ROCK1/PTEN/PI3K/GSK3β pathway in human lung cancer cells

Hirsutine extracted from Uncaria rhynchophylla has been shown to exhibit anti-cancer activity. However, the molecular mechanism by which hirsutine exhibits anti-lung cancer activity remains unclear. In the present study, we showed that hirsutine induces apoptosis in human lung cancer cells via loss of mitochondrial membrane potential (∆ψm), adenosine triphosphate (ATP) depletion, ROS production, as well as cytochrome c release. Dephosphorylation of GSK3β is involved in hirsutine-mediated mitochondrial permeability transition pore (mPTP) opening through ANT1/CypD interaction. Mechanistic study revealed that interruption of ROCK1/PTEN/PI3K/Akt signaling pathway plays a critical role in hirsutine-mediated GSK3β dephosphorylation and mitochondrial apoptosis. Our in vivo study also showed that hirsutine effectively inhibits tumor growth in a A549 xenograft mouse model through ROCK1/PTEN/PI3K/Akt signaling-mediated GSK3β dephosphorylation and apoptosis. Collectively, these findings suggest a hierarchical model in which induction of apoptosis by hirsutine stems primarily from activation of ROCK1 and PTEN, inactivation of PI3K/Akt, leading in turn to GSK3β dephosphorylation and mPTP opening, and culminating in caspase-3 activation and apoptosis. These findings could provide a novel mechanistic basis for the application of hirsutine in the treatment of human lung cancer.

Tubeimoside-1, Triterpenoid Saponin, as a Potential Natural Cancer Killer

Nature, an expert craftsman of molecules, has generated extensive array of bioactive molecular entities. It persists as an inexhaustible resource for discovery of drugs and supplied enormous scaffold diversification for development into effectual drugs to treat multiple pathological conditions. This review provides an update on the sources, biological, and pharmacological effects of nature's gift, a triterpenoid saponin, tubeimoside-1 which is a major bioactive constituent of the bulb of Bolbostemma paniculatum. Tubeimoside-1 is known to possess various pharmacological properties such as anti-cancer, anti-HIV, and anti-inflammatory. Recently, anti-proliferative potential of tubeimoside-1 has been widely studied. The present review article seeks to cover the recent developments of tubeimoside-1′s pharmacological position in the arena of herbal drugs, providing an insight into its current status in therapeutic pursuits. This anti-cancer triterpenoid saponin fight cancer progression by induction of apoptosis, cell cycle arrest, and inhibiting metastasis by specifically targeting multiple signaling pathways those are usually deregulated in various cancers. The reported data recommend tubeimoside-1′s mutitarget activity in preference to single effect that may perform an imperative role towards developing tubeimoside-1 into potential pharmacological drug.

Paclitaxel-induced hypothermia and hypoperfusion increase breast cancer metastasis and angiogenesis in mice

Housing temperature has been shown to influence thermoregulation and behavior of preclinical cancer models; and anti-cancer drugs typically reduce peripheral blood flow and body temperature. In the present study, the effects of paclitaxel (PTX)-induced reduction of body temperature and peripheral blood flow on metastatic 4T1 breast cancer was investigated in a mouse model and the modification of these effects by thermoneutral temperature was also assessed. A single dose of PTX decreased the body temperature and peripheral blood flow in mice housed at a standard temperature (23°C). Furthermore, although lung metastasis and angiogenesis of inoculated 4T1 cells increased in mice pretreated with PTX, mice housed at a thermoneutral temperature (30°C) could compensate their body temperature and peripheral blood flow compared with control mice, and also suppressed 4T1 angiogenesis and metastasis to lung. The present results imply that maintenance of body temperature or efficient energy supply for thermogenesis may prevent tumor relapse or metastasis after chemotherapy.

Hirsutine, an Indole Alkaloid of Uncaria rhynchophylla, Inhibits Late Step in Dengue Virus Lifecycle

Dengue virus (DENV) is transmitted to humans by Aedes mosquitoes and is a public health issue worldwide. No antiviral drugs specific for treating dengue infection are currently available. To identify novel DENV inhibitors, we analyzed a library of 95 compounds and 120 extracts derived from crude drugs (herbal medicines). In the primary screening, A549 cells infected with DENV-1 were cultured in the presence of each compound and extract at a final concentration of 10 μM (compound) and 100 μg/mL (extract), and reduction of viral focus formation was assessed. Next, we eliminated compounds and extracts which were cytotoxic using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hirsutine, an indole alkaloid of Uncaria rhynchophylla, was identified as a potent anti-DENV compound exhibiting high efficacy and low cytotoxicity. Hirsutine showed antiviral activity against all DENV serotypes. Time-of-drug-addition and time-of-drug-elimination assays indicated that hirsutine inhibits the viral particle assembly, budding, or release step but not the viral translation and replication steps in the DENV lifecycle. A subgenomic replicon system was used to confirm that hirsutine does not restrict viral genome RNA replication. Hirsutine is a novel DENV inhibitor and potential candidate for treating dengue fever.

Chemosensitizing Effect of Saikosaponin B on B16F10 Melanoma Cells

Cancer cell resistance to chemotherapy is one of the obstacles for better cancer treatment, and inflammatory signaling pathways, such as NF-κB signaling pathway, have been recognized to be involved in such chemoresistance. In this study, we aim to identify a new approach for overcoming cancer chemoresistance by using natural compounds. As a result of screening by using Murine B16F10 melanoma cell line constitutively expressing NF-κB luciferase reporter gene, we identified Saikosaponin B2 as an effective inhibitor for etoposide-induced NF-κB activation in B16F10NFkB cells. Saikosaponin B2 sensitized etoposide-induced cell death in B16F10 melanoma cells through the induction of apoptosis. Along with apoptosis induction, we observed an induction of γ-H2AX expression, which is a molecular signature for DNA damage, upon the combination treatment of etoposide and Saikosaponin B2. Among Saikosaponin family compounds, we found that Saikosaponin B1, but not Saikosaponin A, sensitized etoposide-induced cytotoxicity implicating the structural requirement of Saikosaponin B for such chemosensitization. By testing the combination of Saikosaponin B1 and B2 with 9 clinical anticancer drugs, Saikosaponin B showed a certain preference in the combination with those tested anticancer drugs. Collectively, we conclude Saikosaponin B can be an attractive adjuvant for enhancing the clinical effect of cancer chemotherapy.

Emerging Cytotoxic Alkaloids in the Battle against Cancer: Overview of Molecular Mechanisms

Considered as the second deadliest disease globally, cancer has captured the attention of researchers who have been trying with perseverance to decode its hidden aspects, to find new prognosis methods, and to develop better and more effective treatments. Plants have continuously offered an excess of unique secondary metabolites with remarkable biological applications. Alkaloids, one of the most abundant metabolites, constitute a large conglomerate of basic heterocyclic nitrogen-containing natural compounds which are normally produced by plants as toxic substances. Out of the 27,000 different alkaloids, more than 17,000 have displayed diversified pharmacological properties including anticancer activities. These metabolites have been classified either according to their chemical structures or their taxonomic origin. None of the researched alkaloids have been classified according to their molecular mechanism of action against cancer. In fact, only a fraction of the tremendous number of anticancer alkaloids has been copiously mentioned in journals. Here, we aim to provide a summary of the literature on some of the promising anticancer alkaloids that have not been well discussed previously and to classify them according to their molecular mechanisms of action. This review will provide a better understanding of the anticancer mechanisms of these promising natural products that are a rich reservoir for drug discovery.

Arctigenin, a lignan from Arctium lappa L., inhibits metastasis of human breast cancer cells through the downregulation of MMP-2/-9 and heparanase in MDA-MB-231 cells

Arctigenin is a bioactive lignan isolated from the seeds of Arctium lappa L. which has been widely used as a diuretic and a diaphoretic in Traditional Chinese Medicine. In the present study, the authors investigated the effects of arctigenin on tumor migration and invasion in aggressive human breast cancer cells. The MTT assay results showed that arctigenin did not show a significant cytotoxic effect on the cell viability of MDA-MB-231 cells. However, wound healing migration and Boyden chamber invasion assays demonstrated that arctigenin significantly inhibited in vitro migration and invasion of the MDA-MB-231 cells. Furthermore, gelatin zymography results showed that arctigenin reduced the activity of MMP-2 and MMP-9. Western blot analysis results demonstrated that the expression of MMP-2, MMP-9 and heparanase proteins was significantly downregulated following the treatment of arctigenin. Finally, the antiangiogenic activity of arctigenin was also examined by the chick embryo chorioallantoic membrane (CAM) assay. Arctigenin treatment significantly inhibited angiogenesis in the CAM. In conclusion, the results revealed that arctigenin significantly inhibited the migration and invasion of MDA-MB-231 cells by downregulating MMP-2, MMP-9 and heparanase expression. However, further studies are still necessary to investigate the exact mechanisms involved and to explore signal transduction pathways to better understand the biological mechanisms.

Targeting the ataxia telangiectasia mutated pathway for effective therapy against hirsutine-resistant breast cancer cells

The present authors have recently demonstrated that hirsutine, one of the major alkaloids in Uncaria species, promotes cell apoptosis by inducing DNA damage and suppresses metastasis of breast cancer cells. Despite its potent anti-cancer activity, certain types of human breast cancer cells exhibit resistance to hirsutine. To maximize the clinical utility of hirsutine therapy against breast cancer, it is critical to explore the underlying mechanism that protects hirsutine-resistant breast cancer cell lines. To identify potential targets for overcoming hirsutine-resistance, the present study investigated a library of kinase inhibitors in combination with hirsutine treatment in the hirsutine-resistant human breast carcinoma MCF-7 cell line. Amongst the 96 compounds tested, inhibitors of the ataxia telangiectasia mutated (ATM) pathway sensitized MCF-7 cells to hirsutine-induced cell death along with a sustained DNA damage response. This sensitization of MCF-7 cells to the hirsutine-induced DNA damage response by interfering with the ATM pathway did not require p53. Instead, radical oxygen species generation was significantly increased in hirsute and ATM inhibitor-treated MCF-7 cells. In conclusion, the present findings suggest the importance of the ATM pathway for optimizing the anti-cancer effect of hirsutine in breast cancer cells.

Mammary tissue microenvironment determines T cell-dependent breast cancer-associated inflammation

Although the importance of the host tissue microenvironment in cancer progression and metastasis has been established, the spatiotemporal process establishing a cancer metastasis-prone tissue microenvironment remains unknown. In this study, we aim to understand the immunological character of a metastasis-prone microenvironment in a murine 4T1 breast tumor model, by using the activation of nuclear factor-κb (NF-κB) in cancer cells as a sensor of inflammatory status and by monitoring its activity by bioluminescence imaging. By using a 4T1 breast cancer cell line stably expressing an NF-κB/Luc2 reporter gene (4T1 NF-κB cells), we observed significantly increased bioluminescence approximately 7 days after metastasis-prone orthotopic mammary fat-pad inoculation but not ectopic s.c. inoculation of 4T1 NF-κB cells. Such in vivo NF-κB activation within the fat-pad 4T1 tumor was diminished in immune-deficient SCID or nude mice, or T cell-depleted mice, suggesting the requirement of host T cell-mediated immune responses. Given the fat-pad 4T1 tumor expressed higher inflammatory mediators in a T cell-dependent mechanism compared to the s.c. tumor, our results imply the importance of the surrounding tissue microenvironment for inflaming tumors by collaborating with T cells to instigate metastatic spread of 4T1 breast cancer cells.

Selective anticancer activity of hirsutine against HER2‑positive breast cancer cells by inducing DNA damage

Hirsutine is one of the major alkaloids isolated from plants of the Uncaria genus and is known for its cardioprotective, anti‑hypertensive and anti-arrhythmic activities. We recently reported that hirsutine is an anti-metastatic phytochemical by targeting NF-κB activation in a murine breast cancer model. In the present study, we further examined the clinical utility of hirsutine against human breast cancer. Among six distinct human breast cancer cell lines, hirsutine showed strong cytotoxicity against HER2-positive/p53-mutated MDA-MB‑453 and BT474 cell lines. Conversely, HER2-negative/p53 wild‑type MCF-7 and ZR-75-1 cell lines showed resistance against hirsutine-induced cytotoxicity. Hirsutine induced apoptotic cell death in the MDA-MB-453 cells, but not in the MCF-7 cells, through activation of caspases. Furthermore, hirsutine induced the DNA damage response in the MDA-MB-453 cells, but not in the MCF-7 cells, as highlighted by the upregulation of γH2AX expression. Along with the induction of the DNA damage response, the suppression of HER2, NF-κB and Akt pathways and the activation of the p38 MAPK pathway in the MDA-MB-453 cells were observed. Considering that there was no difference between MDA-MB-453 and MCF-7 cells in regards to irinotecan‑induced DNA damage response, our present results indicate the selective anticancer activity of hirsutine in HER2-positive breast cancer by inducing a DNA damage response.