Terrein induces apoptosis in HeLa human cervical carcinoma cells through p53 and ERK regulation

Virucidal activity of tiliacorinine, dioscorine, racemosol, and terrein against influenza A virus (H1N1), coronavirus 229E, SARS-CoV-2, and enterovirus 71

Emerging infectious diseases such as COVID-19 and Disease X, which was detected in the Democratic Republic of the Congo in early December 2024, underscore the importance of developing new virucidal, antiviral, and antimicrobial compounds. The virucidal activity of natural products, including tiliacorinine (1), dioscorine (2), racemosol (3), and terrein (4), against influenza A virus (H1N1), human coronavirus 229E (HCoV-229E), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and enterovirus 71 (EV71) were evaluated using the American Society for Testing and Materials E1053-20 method. Racemosol (3) from Bauhinia malabarica had the most potent virucidal activity against the H1N1, HCoV-229E, and SARS-CoV-2 viruses, followed by terrein (4), a metabolite of the fungus Aspergillus terreus. Racemosol (3) exhibited virucidal activity with a log reduction of 4 (99.99 % viral reduction) against H1N1, HCoV-229E, and SARS-CoV-2 at a concentration of 0.1250 mg/mL. The alkaloids tiliacorinine (1) from Tiliacora triandra and dioscorine (2) from Dioscorea hispida exhibited weaker virucidal activity than racemosol (3) and terrein (4). Compounds 1, 2, and 4 showed weak virucidal activity against the EV71 virus, while racemosol (3) displayed moderate activity with a log reduction of 3.813 at the concentration of 0.1250 mg/mL. This work underscores the importance of natural products as sources of virucidal agents, which may be useful for the future threats of emerging and re-emerging viral diseases.

Limonoid-rich fraction from Azadirachta indica A. Juss. (neem) stem bark triggers ROS-independent ER stress and induces apoptosis in 2D cultured cervical cancer cells and 3D cervical tumor spheroids

BACKGROUND

The existing anticancer drugs in clinical practice show poor efficacy in cervical cancer patients and are associated with multiple side effects. Our previous study demonstrated the strong antineoplastic activity of crude extract prepared from the stem bark of Azadirachta indica (Neem) against cervical cancer. However, the active phytoconstituents of neem stem bark extract and its underlying anticancer mechanism are yet to be investigated. Thus, the present study aimed to identify the active fraction from crude neem stem bark extract to further dissect its anticancer mechanism and determine the active components.

METHODS

Dichloromethane (DCM) extract from neem stem bark was prepared and fractionated using thin-layer chromatography. The fractions obtained were screened against HeLa and ME-180 cervical cancer cell lines to identify the most active fraction, which was then selected for further studies. Clonogenic assay, cell cycle analysis, apoptosis assay, and reactive oxygen species (ROS) assay were performed to determine the cytotoxicity of the active fraction. Gene expression was analyzed using real-time PCR and western blot to determine the mechanism. Additionally, the HeLa cells-derived 3D spheroid model was used to determine the antitumor efficacy of the active fraction. Electrospray ionization-mass spectrometry, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance were used to identify the phytoconstituents of the fraction.

RESULTS

Initial screening revealed fraction 2 (F2) as the most active fraction. Additionally, F2 showed the least cytotoxic effect on normal human fibroblast cells. Mechanistically, F2 induced cell cycle arrest and apoptosis in cervical cancer cells. F2 increased ROS levels, induced ER stress, and activated cell survival pathway. Treatment with N-acetyl cysteine revealed that F2 induced ROS-independent ER stress and apoptosis. 3D spheroid viability and growth delay experiments demonstrated the strong antitumor potential of F2. Finally, six compounds, including one flavonoid (nicotiflorin) and five limonoids, were identified in the F2 fraction.

CONCLUSION

This is the first study to identify the active fraction and its phytoconstituents from neem stem bark and demonstrate the anticancer mechanism against cervical cancer. Our study highlights the importance of investigating neem stem bark-derived limonoids and nicotiflorin as a potential source to develop new anticancer therapeutic agents.

Terrein: isolation, chemical synthesis, bioactivity and future prospects of a potential therapeutic fungal metabolite

The increasing risk of drug-resistant infections and unexpected pandemics like Covid-19 has prompted researchers to explore the area of drug repurposing. Natural products, being a result of the evolutionary optimisation processes can be potential starting points for such drug discovery programs. One such unexplored chemical is terrein, a secondary fungal metabolite. Although discovered in 1935 from Aspergillus terreus, the therapeutic potential of terrein has largely remained undeciphered. Research has primarily been focused on its biosynthetic pathways and its mycotoxic effects. However, in the last two decades, its biological properties including anticancer, anti-inflammatory anti-melanogenic, and bacteriocidal activities have been reported. These reports are preliminary in nature and do not adequately establish its overall therapeutic application. From its structural and therapeutic properties, it can be conjectured that terrein may act as a novel multimodal therapeutic. This comprehensive study reviews the synthesis, production and application aspects of terrein to understand its importance.

Bioprospecting of Aspergillus sp. as a promising repository for anti-cancer agents: a comprehensive bibliometric investigation

Cancer remains a significant global health challenge, claiming nearly 10 million lives in 2020 according to the World Health Organization. In the quest for novel treatments, fungi, especially Aspergillus species, have emerged as a valuable source of bioactive compounds with promising anticancer properties. This study conducts a comprehensive bibliometric analysis to map the research landscape of Aspergillus in oncology, examining publications from 1982 to the present. We observed a marked increase in research activity starting in 2000, with a notable peak from 2005 onwards. The analysis identifies key contributors, including Mohamed GG, who has authored 15 papers with 322 citations, and El-Sayed Asa, with 14 papers and 264 citations. Leading countries in this research field include India, Egypt, and China, with King Saud University and Cairo University as the leading institutions. Prominent research themes identified are "endophyte," "green synthesis," "antimicrobial," "anti-cancer," and "biological activities," indicating a shift towards environmentally sustainable drug development. Our findings highlight the considerable potential of Aspergillus for developing new anticancer therapies and underscore the necessity for further research to harness these natural compounds for clinical use.

A Focused Review of the Pharmacological Potentials of Terrein as an Anticancer Agent

Terrein is one of the most important biomolecules of fungal origin being studied from a medicinal perspective. Secondary metabolites are the intermediate products produced during the metabolism of organisms for a large number of functions, for example, defense and communication signals. From the outset, terrein has largely been studied as an anticancer secondary biomolecule. Aspergillus terreus is the only fungal source of some valuable drugs and mycotoxins. From the beginning, a few species of Aspergillus were known to be viable chemical factories. Terrein is a potent biological molecule present in the fungus that is responsible for its medicinal and agricultural values. Numerous evaluations conducted on terrein showed it to have marked biological activities (antimicrobial, antiproliferative, anti-oxidative, and others). To date, terrein has emerged as a very attractive therapeutic regimen against cancer due to its dual targeting nature; tumor angiogenesis and cell proliferation. This focused review provides details of the therapeutic value of terrein and its modes of action as an anticancer agent. Besides this, terrein has other marked bioactivities and manifold uses in the field of medicine, which have also been discussed here.

Chemomodulatory Effect of the Marine-Derived Metabolite "Terrein" on the Anticancer Properties of Gemcitabine in Colorectal Cancer Cells

BACKGROUND

Terrein (Terr) is a bioactive marine secondary metabolite that possesses antiproliferative/cytotoxic properties by interrupting various molecular pathways. Gemcitabine (GCB) is an anticancer drug used to treat several types of tumors such as colorectal cancer; however, it suffers from tumor cell resistance, and therefore, treatment failure.

METHODS

The potential anticancer properties of terrein, its antiproliferative effects, and its chemomodulatory effects on GCB were assessed against various colorectal cancer cell lines (HCT-116, HT-29, and SW620) under normoxic and hypoxic (pO₂ ≤ 1%) conditions. Further analysis via flow cytometry was carried out in addition to quantitative gene expression and ¹HNMR metabolomic analysis.

RESULTS

In normoxia, the effect of the combination treatment (GCB + Terr) was synergistic in HCT-116 and SW620 cell lines. In HT-29, the effect was antagonistic when the cells were treated with (GCB + Terr) under both normoxic and hypoxic conditions. The combination treatment was found to induce apoptosis in HCT-116 and SW620. Metabolomic analysis revealed that the change in oxygen levels significantly affected extracellular amino acid metabolite profiling.

CONCLUSIONS

Terrein influenced GCB's anti-colorectal cancer properties which are reflected in different aspects such as cytotoxicity, cell cycle progression, apoptosis, autophagy, and intra-tumoral metabolism under normoxic and hypoxic conditions.

Protection against Lipopolysaccharide-Induced Endotoxemia by Terrein Is Mediated by Blocking Interleukin-1β and Interleukin-6 Production

Terrein is a fungal metabolite and has been known to exert anti-melanogenesis, anti-cancer, and anti-bacterial activities. However, its role in endotoxemia has never been investigated until now. In the present study, we examined the effect of terrein on lipopolysaccharide (LPS)-induced endotoxemia in mice and characterized the potential mechanisms of action. Treatment with terrein increased the survival of mice and decreased the production of inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-6 (IL-6) in an LPS-induced endotoxemia model. In addition, terrein suppressed the LPS-induced production of IL-1β and IL-6 in RAW 264.7 cells, a murine macrophage-like cell line, and the mRNA expression of IL-1β and IL-6 was also inhibited by terrein in LPS-stimulated RAW 264.7 cells. Further study demonstrated that terrein blocked LPS-induced phosphorylation of p65 subunit of nuclear factor (NF)/κB and the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) was also suppressed by terrein treatment. Collectively, these results suggest that terrein exerts a protective effect again LPS-induced endotoxemia in mice by blocking the production of inflammatory cytokines. Our results also suggest that the anti-inflammatory effect of terrein might be mediated, at least in part, by blocking the activation of NF-κB, JNK, and p38 MAPK signaling pathways.

Methanolic neem (Azadirachta indica) stem bark extract induces cell cycle arrest, apoptosis and inhibits the migration of cervical cancer cells in vitro

Background

Cervical cancer remains one of the significant causes of mortality in women due to the limitations of current treatment strategies and their associated side effects. Investigation of alternative medicine, including phytomedicine, has shown effective anti-cancer potential with fewer side effects. Azadirachta indica (commonly known as neem) is known for its medicinal properties. The present study investigated the anti-cancer potential of methanolic neem stem bark extract (MNBE) against cervical cancer using HeLa, SiHa, and ME-180 cell lines.

Methods

Cytotoxic effect of MNBE on cultured cell lines was evaluated by MTT and clonogenic assay. The growth-inhibiting effect of MNBE was further confirmed by performing cell cycle analysis and apoptosis assay using flow cytometry. The anti-migratory effect of MNBE was evaluated by using wound healing and Boyden chamber assay. Real-time PCR was used to determine the mRNA expression, and western blot and flow cytometry was used to determine the protein levels of growth and migration-related genes.

Results

MNBE significantly suppressed the growth and survival of cervical cancer cells in a dose-dependent manner by inducing cell cycle arrest and apoptosis. In addition, the growth inhibitory effect of MNBE was specific to cervical cancer cells than normal cells. Cell cycle arrest was correlated to transcriptional downregulation of cyclin dependent kinase 1 (CDK1), cyclin A, and cyclin B. Additionally, MNBE treatment resulted in the upregulation of active caspase-3 protein and downregulation of prosurvival genes, Bcl2, and survivin at mRNA level and NFkB-p65 at the protein level. Furthermore, MNBE inhibited the migration of cervical cancer cells accompanied by modulation of migration-related genes, including zona occludens-1 (ZO-1), matrix metalloproteinase 2 (MMP2), focal adhesion kinase (FAK), N-cadherin, snail, and E-cadherin.

Conclusion

In summary, the present study provides the first evidence of MNBE in restricting cervical cancer cell growth and migration, which warrants further investigation for developing novel anti-cancer drugs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03718-7.

Enhanced production of terrein in marine-derived Aspergillus terreus by refactoring both global and pathway-specific transcription factors

Background

Terrein, a major secondary metabolite from Aspergillus terreus, shows great potentials in biomedical and agricultural applications. However, the low fermentation yield of terrein in wild A. terreus strains limits its industrial applications.

Results

Here, we constructed a cell factory based on the marine-derived A. terreus RA2905, allowing for overproducing terrein by using starch as the sole carbon source. Firstly, the pathway-specific transcription factor TerR was over-expressed under the control of a constitutive gpdA promoter of A. nidulans, resulting in 5 to 16 folds up-regulation in terR transcripts compared to WT. As expected, the titer of terrein was improved in the two tested terR OE mutants when compared to WT. Secondly, the global regulator gene stuA, which was demonstrated to suppress the terrein synthesis in our analysis, was deleted, leading to greatly enhanced production of terrein. In addition, LS-MS/MS analysis showed that deletion of StuA cause decreased synthesis of the major byproduct butyrolactones. To achieve an optimal strain, we further refactored the genetic circuit by combining deletion of stuA and overexpression of terR, a higher terrein yield was achieved with a lower background of byproducts in double mutants. In addition, it was also found that loss of StuA (both ΔstuA and ΔstuA::OEterR) resulted in aconidial morphologies, but a slightly faster growth rate than that of WT.

Conclusion

Our results demonstrated that refactoring both global and pathway-specific transcription factors (StuA and TerR) provides a high-efficient strategy to enhance terrein production, which could be adopted for large-scale production of terrein or other secondary metabolites in marine-derived filamentous fungi.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01859-5.

TerC Is a Multifunctional and Promiscuous Flavoprotein Monooxygenase That Catalyzes Bimodal Oxidative Transformations

The flavoprotein monooxygenase (FPMO) TerC is encoded by all known cyclopentene biosynthetic gene clusters. It can catalyze oxidative dearomatization toward a series of 6-HM analogues and further induces different skeletal distortions to form either benzoquinone or pyrone by bimodal reaction cascades, which is only governed by the C7 substitutions. Beyond our study demonstrated bimodal reaction cascades and advanced the biosynthetic knowledge of fungal cyclopentenes, this work also sets the stage for the bioengineering of 6-HM polyketides.

Recent Advances in Isolation, Synthesis and Biological Evaluation of Terrein

Terrein is a small-molecule polyketide compound with a simple structure mainly isolated from fungi. Since its discovery in 1935, many scholars have conducted a series of research on its structure identification, isolation source, production increase, synthesis and biological activity. Studies have shown that terrein has a variety of biological activities, not only can inhibit melanin production and epidermal hyperplasia, but also has anti-cancer, anti-inflammatory, anti-angiopoietic secretion, antibacterial, insecticidal activities, and so on. It has potential application prospects in beauty, medicine, agriculture and other fields. This article reviews the process of structural identification of terrein since 1935, and summarizes the latest advances in its isolation, source, production increase, synthesis, and biological activity evaluation, with a view to providing a reference and helping for the in-depth research of terrein.

Aspergillus terreus Species Complex

Infections due to Aspergillus species are an acute threat to human health; members of the Aspergillus section Fumigati are the most frequently occurring agents, but depending on the local epidemiology, representatives of section Terrei or section Flavi are the second or third most important. Aspergillus terreus species complex is of great interest, as it is usually amphotericin B resistant and displays notable differences in immune interactions in comparison to Aspergillus fumigatus. The latest epidemiological surveys show an increased incidence of A. terreus as well as an expanding clinical spectrum (chronic infections) and new groups of at-risk patients being affected. Hallmarks of these non-Aspergillus fumigatus invasive mold infections are high potential for tissue invasion, dissemination, and possible morbidity due to mycotoxin production. We seek to review the microbiology, epidemiology, and pathogenesis of A. terreus species complex, address clinical characteristics, and highlight the underlying mechanisms of amphotericin B resistance. Selected topics will contrast key elements of A. terreus with A. fumigatus. We provide a comprehensive resource for clinicians dealing with fungal infections and researchers working on A. terreus pathogenesis, aiming to bridge the emerging translational knowledge and future therapeutic challenges on this opportunistic pathogen.

Inhibitory effects of terrein on lung cancer cell metastasis and angiogenesis

Cancer metastasis is the leading cause of mortality in cancer patients. Over 70% of lung cancer patients are diagnosed at advanced or metastatic stages, and this results in an increased incidence of mortality. Terrein is a secondary bioactive fungal metabolite isolated from Aspergillus terreus. Numerous studies have demonstrated that terrein has anticancer properties, but in the present study, the cellular mechanisms underlying the inhibition of lung cancer cell metastasis by terrein was investigated for the first time. Using MTT assays, the cytotoxic effects of terrein were first examined in human lung cancer cells (A549 cells) and then compared with its cytotoxic effects in three noncancer control cell lines (Vero kidney, L6 skeletal muscle and H9C2 cardiomyoblast cells). The results indicated that terrein significantly reduced the viability of all these cells but exhibited a different level of toxicity in each cell type; these results revealed a specific concentration range in which the effect of terrein was specific to A549 cells. This significant cytotoxic effect of terrein in A549 cells was verified using LDH assays. It was then demonstrated that terrein attenuated the proliferation of A549 cells using IncuCyte image analysis. Regarding its antimetastatic effects, terrein significantly inhibited A549 cell adhesion, migration and invasion. In addition, terrein suppressed the angiogenic processes of A549 cells, including vascular endothelial growth factor (VEGF) secretion, capillary-like tube formation and VEGF/VEGFR2 interaction. These phenomena were accompanied by reduced protein levels of integrins, FAK, and their downstream mediators (e.g., PI3K, AKT, mTORC1 and P70S6K). All these data indicated that terrein was able to inhibit all the major metastatic processes in human lung cancer cells, which is crucial for cancer treatment.

Chemical Investigation of Marine-Derived Fungus Aspergillus flavipes for Potential Anti-Inflammatory Agents

The marine fungus, Aspergillus flavipes (MTCC 5220), was isolated from the pneumatophore of a mangrove plant Acanthus ilicifolius found in Goa, India. The crude extract of A. flavipes was found to show anti-inflammatory activity. It blocked interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) production in lipopolysaccharide (LPS)-activated THP-1 cells with IC₅₀ of 2.69±0.5 μM and 6.64±0.4 μM, respectively. The chemical investigation led to the isolation of optically inactive 4β-[(1E)-propen-1-yl]cyclopentane-1β,2β-diol (1) along with a new optically active diastereoisomeric compound, 4β-[(1E)-propen-1-yl]cyclopentane-1β,2α-diol (2). In addition, the fungus also produced known compounds (+)-terrein (3), butyrolactone I (4) and butyrolactone II (5) in high yields. Among these, (+)-terrein (3) exhibited IL-6 and TNF-α inhibition activity with IC₅₀ of 8.5±0.68 μM and 15.76±0.18 μM, respectively, while butyrolactone I (4) exhibited IC₅₀ of 12.03±0.85 μM (IL-6) and 43.29±0.76 μM (TNF-α) inhibition activity with low toxicity to host cells in LPS stimulated THP-1 cells. This is the first report of the isolation and characterization of 4β-[(1E)-propen-1-yl]cyclopentane-1β,2α-diol (2). The structures of all the isolated compounds were elucidated on the basis of extensive detailed NMR spectroscopic data. Anti-inflammatory activity of the fungi A. flavipes is presented here for the first time, which was due to (+)-terrein and butyrolactone I, as the major constituents and they can be further explored in the therapeutic area.

Anticancer activity and molecular mechanisms of α-conidendrin, a polyphenolic compound present in Taxus yunnanensis, on human breast cancer cell lines

α-Conidendrin is a polyphenolic compound found mainly in Taxus yunnanensis, as the source of chemotherapy drug paclitaxel, which has been used in traditional medicine for treatment of cancer. This study aimed to investigate the anticancer activity and molecular mechanisms of α-conidendrin on breast cancer cell lines. The results of the present study show that α-conidendrin possesses potent antiproliferative effects on breast cancer cell lines MCF-7 and MDA-MB-231. α-Conidendrin significantly induced apoptosis in breast cancer cells via reactive oxygen species generation, upregulation of p53 and Bax, downregulation of Bcl-2, depolarization of mitochondrial membrane potential (MMP), release of cytochrome c from mitochondria, and activation of caspases-3 and -9. α-Conidendrin remarkably inhibited the proliferation of breast cancer cells through induction of cell cycle arrest by upregulating p53 and p21 and downregulating cyclin D1 and CDK4. Unlike breast cancer cells, the antiproliferative effect of α-conidendrin on human foreskin fibroblast cells (normal cells) was very small. In normal cells, reactive oxygen species levels, loss of MMP, release of cytochrome c, mRNA expression of p53, p21, cyclin D1, CDK4, Bax, and Bcl-2 as well as mRNA expression and activity of caspases-3 and -9 were significantly less affected by α-conidendrin compared with cancer cells. These results suggest that α-conidendrin can be a promising agent for treatment of breast cancer with little or no toxicity against normal cells.

3-Bromopyruvate potentiates TRAIL-induced apoptosis in human colon cancer cells through a reactive oxygen species- and caspase-dependent mitochondrial pathway

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a promising anticancer cytokine with minimal toxicity towards normal cells. Nevertheless, most primary cancers are often intrinsically TRAIL-resistant or can acquire resistance after TRAIL therapy. This study aimed to investigate the inhibitory effect of co-treatment of 3-bromopyruvate (3-BP) as a potent anticancer agent with TRAIL on colon cancer cells (HT-29). The results of present study indicated that combined treatment with 3-BP and TRAIL inhibited the proliferation of HT-29 cells to a greater extent (88.4%) compared with 3-BP (54%) or TRAIL (11%) treatment alone. In contrast, the combination of 3-BP and TRAIL had no significant inhibitory effect on the proliferation of normal cells (HEK-293) (8.4%). At a cellular mechanistic level, the present study showed that 3-BP sensitized human colon cancer cells to TRAIL-induced apoptosis via reactive oxygen species generation, upregulation of Bax, downregulation of Bcl-2 and survivin, release of cytochrome c into the cytosol, and activation of caspase-3. In normal cells, 3-BP, TRAIL, or combination of both had no significant effect on the reactive oxygen species levels, release of cytochrome c, and caspase-3 activity. Therefore, the combination of 3-BP and TRAIL can be a promising therapeutic strategy for treatment of colon cancer.

Modulation of Diacylglycerol-Induced Melanogenesis in Human Melanoma and Primary Melanocytes: Role of Stress Chaperone Mortalin

Skin color/pigmentation is regulated through melanogenesis process in specialized melanin-producing cells, melanocytes, involving multiple signaling pathways. It is highly influenced by intrinsic and extrinsic factors such as oxidative, ultraviolet radiations and other environmental stress conditions. Besides determining the color, it governs response and tolerance of skin to a variety of environmental stresses and pathological conditions including photodamage, hyperpigmentation, and skin cancer. Depigmenting reagents have been deemed useful not only for cosmetics but also for pigmentation-related pathologies. In the present study, we attempted modulation of 1-oleoyl-2-acetyl-glycerol- (OAG-) induced melanogenesis in human melanoma and primary melanocytes. In both cell types, OAG-induced melanogenesis was associated with increase in enhanced expression of melanin, tyrosinase, as well as stress chaperones (mortalin and HSP60) and Reactive Oxygen Species (ROS). Treatment with TXC (trans-4-(Aminomethyl) cyclohexanecarboxylic acid hexadecyl ester hydrochloride) and 5/40 natural compounds resulted in their reduction. The data proposed an important role of mortalin and oxidative stress in skin pigmentation and the use of TXC and natural extracts for modulation of pigmentation pathways in normal and pathological conditions.

Terrein is an inhibitor of quorum sensing and c-di-GMP in Pseudomonas aeruginosa: a connection between quorum sensing and c-di-GMP

To address the drug-resistance of bacterial pathogens without imposing a selective survival pressure, virulence and biofilms are highly attractive targets. Here, we show that terrein, which was isolated from Aspergillus terreus, reduced virulence factors (elastase, pyocyanin, and rhamnolipid) and biofilm formation via antagonizing quorum sensing (QS) receptors without affecting Pseudomonas aeruginosa cell growth. Additionally, the effects of terrein on the production of QS signaling molecules and expression of QS-related genes were verified. Interestingly, terrein also reduced intracellular 3,5-cyclic diguanylic acid (c-di-GMP) levels by decreasing the activity of a diguanylate cyclase (DGC). Importantly, the inhibition of c-di-GMP levels by terrein was reversed by exogenous QS ligands, suggesting a regulation of c-di-GMP levels by QS; this regulation was confirmed using P. aeruginosa QS mutants. This is the first report to demonstrate a connection between QS signaling and c-di-GMP metabolism in P. aeruginosa, and terrein was identified as the first dual inhibitor of QS and c-di-GMP signaling.

Diepoxybutane-induced apoptosis is mediated through the ERK1/2 pathway

Diepoxybutane (DEB) is the most potent active metabolite of butadiene, a regulated air pollutant. We previously reported the occurrence of DEB-induced, p53-dependent, mitochondrial-mediated apoptosis in human lymphoblasts. The present study investigated the role of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) pathway in DEB-induced apoptotic signaling in exposed human lymphoblasts. Activated ERK1/2 and mitogen-activated protein (MAP) kinase/ERK1/2 kinase (MEK) levels were significantly upregulated in DEB-exposed human lymphoblasts. The MEK inhibitor PD98059 and ERK1/2 siRNA significantly inhibited apoptosis, ERK1/2 activation, as well as p53 and phospho-p53 (serine-15) levels in human lymphoblasts undergoing DEB-induced apoptosis. Collectively, these results demonstrate that DEB induces apoptotic signaling through the MEK-ERK1/2-p53 pathway in human lymphoblasts. This is the first report implicating the activation of the ERK1/2 pathway and its subsequent role in mediating DEB-induced apoptotic signaling in human lymphoblasts. These findings contribute towards the understanding of DEB toxicity, as well as the signaling pathways mediating DEB-induced apoptosis in human lymphoblasts.

Inhibited effects of CAPE-pNO2 on cervical carcinoma in vivo and in vitro and its detected metabolites

The development of advanced cervical cancer therapies is a particularly urgent need due to the strong side effects and toxicities of current treatments. Caffeic acid phenethyl ester (CAPE) exhibits broad-spectrum antitumor activities and little toxicity or side effects. In our previous study, caffeic acid para-nitro phenethyl ester (CAPE-pNO₂) significantly improved the effect of anti-platelet aggregation and attenuated myocardial ischemia. Based on this finding, we aimed to further explore the antitumor activity of CAPE-pNO₂ in cervical cancer cells and tumor xenografts. In addition, we assessed the biotransformation of CAPE-pNO₂ in cervical cancer cells. Our study demonstrated that both CAPE and CAPE-pNO₂ can inhibit cell proliferation via the induction of G2/M cell cycle arrest. More importantly, CAPE-pNO₂ dramatically induced cell apoptosis via significant down-regulation of pro-caspase-3, pro-caspase-9, Bcl-2, Cyclin B1 and Cdc2 and up-regulation of cleaved-caspase-3, Bax, CytoC and P21^Cip1. Moreover, CAPE and CAPE-pNO₂ significantly suppressed the growth and angiogenesis of nude mice xenografts. CAPE and CAPE-pNO₂ were found to degrade into four and six metabolites, respectively. The metabolites of CAPE and CAPE-pNO₂ were different, and the major metabolic pathway may be phase II reactions. These results suggest that CAPE-pNO₂ induced cell apoptosis and cell cycle arrest via a strong regulatory effect on relevant apoptotic proteins. Therefore, CAPE-pNO₂ should be further studied as a potent anti-cancer agent.

Isolation and Characterization of "Terrein" an Antimicrobial and Antitumor Compound from Endophytic Fungus Aspergillus terreus (JAS-2) Associated from Achyranthus aspera Varanasi, India

The present study aimed at characterizing biological potentials of endophyte Aspergillus terreus JAS-2 isolated from Achyranthus aspera. Crude extracted from endophytic fungus JAS-2 was purified and chemically characterized by chromatographic and spectroscopic studies respectively. Spectral assignment of NMR (nuclear magnetic resonance) data, ¹H proton and ¹³C carbon analysis along with FTIR data elucidated the structure of compound as 4,5-Dihydroxy-3-(1-propenyl)-2-cyclopenten-1-one. After purification and identification a set of experiment was conducted to explore efficacy of compound. Results revealed that on accessing the antifungal activity of compound, growth diameter of tested phytopathogenic fungi was reduced to 50% at higher concentration taken (10 μgμl⁻¹). Compound exhibited in-vitro bacterial cell inhibition at 20 μgml⁻¹ concentration along with moderate antioxidant behavior. Evaluation of anticancer activity against human lung cancer cell line (A-549) exhibited its IC₅₀ value to be 121.9 ± 4.821 μgml⁻¹. Further cell cycle phase distribution were analyzed on the basis of DNA content and evaluated by FACS (Fluorescence Activated Cell Sorting) and it was revealed that at 150 μgml⁻¹ of compound maximum cells were found in sub G1 phase which represents apoptotic dead cells. Terrein (4, 5-Dihydroxy-3-(1-propenyl)-2-cyclopenten-1-one) a multi-potential was isolated from endophytic fungus JAS-2, from well recognized medicinal herb A. aspera. To best of our knowledge, this is the first report of “Terrein” from endophytic derived fungus. This compound had also exhibited anticancer and antifungal activity against human lung cancer cell line A-549 and Bipolaris sorokiniana respectively which is causal organism of many plants disease. Hence endophytes are serving as alternative sources of drug molecules.

Terrein performs antitumor functions on esophageal cancer cells by inhibiting cell proliferation and synergistic interaction with cisplatin

Terrein is a bioactive fungal metabolite isolated from Aspergillus terreus. Besides being a melanogenesis inhibitor, previous studies have revealed that terrein has antiproliferative effects on a number of types of cancer tumors. In the present study, the inhibitory effect of terrein on esophageal cancer was evaluated and the possible underlying mechanisms were investigated. The results revealed that terrein inhibited the proliferation of Eca109 esophageal cancer cells in a dose- and time-dependent manner. Mechanistically, terrein treatment led to the G₂/M phase arrest of Eca109 cells by indirectly regulating cyclin B1 and phosphorylating the cell division cycle protein 2 genes. Notably, terrein exhibited a synergistic effect on Eca109 cells when combined with cisplatin, which is a commonly used chemotherapeutic drug. Taken together, these findings indicate that terrein suppresses the proliferation of esophageal cancer cells, and may prove to be a novel therapeutic approach for the treatment of esophageal cancer via inhibiting the proliferation of cancer cells.

Polyketides in Aspergillus terreus: biosynthesis pathway discovery and application

The knowledge of biosynthesis gene clusters, production improving methods, and bioactivity mechanisms is very important for the development of filamentous fungi metabolites. Metabolic engineering and heterologous expression methods can be applied to improve desired metabolite production, when their biosynthesis pathways have been revealed. And, stable supplement is a necessary basis of bioactivity mechanism discovery and following clinical trial. Aspergillus terreus is an outstanding producer of many bioactive agents, and a large part of them are polyketides. In this review, we took polyketides from A. terreus as examples, focusing on 13 polyketide synthase (PKS) genes in A. terreus NIH 2624 genome. The biosynthesis pathways of nine PKS genes have been reported, and their downstream metabolites are lovastatin, terreic acid, terrein, geodin, terretonin, citreoviridin, and asperfuranone, respectively. Among them, lovastatin is a well-known hypolipidemic agent. Terreic acid, terrein, citreoviridin, and asperfuranone show good bioactivities, especially anticancer activities. On the other hand, geodin and terretonin are mycotoxins. So, biosynthesis gene cluster information is important for the production or elimination of them. We also predicted three possible gene clusters that contain four PKS genes by homologous gene alignment with other Aspergillus strains. We think that this is an effective way to mine secondary metabolic gene clusters.

Stress chaperone mortalin regulates human melanogenesis

In order to identify the cellular factors involved in human melanogenesis, we carried out shRNA-mediated loss-of-function screening in conjunction with induction of melanogenesis by 1-oleoyl-2-acetyl-glycerol (OAG) in human melanoma cells using biochemical and visual assays. Gene targets of the shRNAs (that caused loss of OAG-induced melanogenesis) and their pathways, as determined by bioinformatics, revealed involvement of proteins that regulate cell stress response, mitochondrial functions, proliferation, and apoptosis. We demonstrate, for the first time, that the mitochondrial stress chaperone mortalin is crucial for melanogenesis. Upregulation of mortalin was closely associated with melanogenesis in in vitro cell-based assays and clinical samples of keloids with hyperpigmentation. Furthermore, its knockdown resulted in compromised melanogenesis. The data proposed mortalin as an important protein that may be targeted to manipulate pigmentation for cosmetic and related disease therapeutics.

Terrein reduces age-related inflammation induced by oxidative stress through Nrf2/ERK1/2/HO-1 signalling in aged HDF cells

This study investigated whether multiple bioactivity of terrein such as anti-inflammatory and anti-oxidant inhibits age-related inflammation by promoting an antioxidant response in aged human diploid fibroblast (HDF) cells. HDF cells were cultured serially for in vitro replicative senescence. To create the ageing cell phenotype, intermediate stage (PD31) HDF cells were brought to stress-induced premature senescence (SIPS) using hydrogen peroxide (H2 O2). Terrein increased cell viability even with H2O2 stress and reduced inflammatory molecules such as intracellular adhesion molecule-1 (ICAM-1), cyclooxygenase-2 (COX-2), interleukin-1beta (IL-1β) and tumour necrosis factor-alpha (TNF-α). Terrein reduced also phospho-extracellular kinase receptor1/2 (p-EKR1/2) signalling in aged HDF cells. SIPS cells were attenuated for age-related biological markers including reactive oxygen species (ROS), senescence associated beta-galactosidase (SA β-gal.) and the aforementioned inflammatory molecules. Terrein induced the induction of anti-oxidant molecules, copper/zinc-superoxide defence (Cu/ZnSOD), manganese superoxide dismutase (MnSOD) and heme oxygenase-1 (HO-1) in SIPS cells. Terrein also alleviated reactive oxygen species formation through the Nrf2/HO-1/p-ERK1/2 pathway in aged cells. The results indicate that terrein has an alleviative function of age-related inflammation characterized as an anti-oxidant. Terrein might be a useful nutraceutical compound for anti-ageing.

Modification of artificial sea water for the mass production of (+)-terrein by Aspergillus terreus strain PF26 derived from marine sponge Phakellia fusca

(+)-Terrein shows multiple bioactivities, however, its mass production is a big challenge. Aspergillus terreus strain PF26 derived from South China Sea sponge Phakellia fusca has been cultured to produce (+)-terrein successfully, but artificial sea water (ASW) of high salinity used in the fermentation medium may cause the corrosion risk of metal bioreactor, which limits the fermentation on a large scale. In this study, we modified the components of ASW by removing NaCl and CaCl2 from the original formula, which reduced about 80% salinity of ASW. As a result, 7·56 g l(-1) (+)-terrein production was achieved in shake flask, which was 78·72% higher than using the original ASW, and the cultivation time was decreased from 24 to 15 days. Then, the modified ASW was used for the fermentation of A. terreus strain PF26 in a 500 l stirred bioreactor, consequently 2·5 g l(-1) of (+)-terrein production was achieved.

SIGNIFICANCE AND IMPACT OF THE STUDY

The fermentation of marine micro-organisms always needs to use sea water or artificial sea water (ASW), which limits the fermentation on a large scale, as the high-salinity medium may cause the corrosion risk of bioreactor. In this study, the ASW formula is simplified to reduce the sea water salinity and improve the yield of (+)-terrein, finally, the modified ASW was successfully used for the mass production of (+)-terrein by A. terreus strain PF26 in a 500 l bioreactor.

Splicing function of mitotic regulators links R-loop-mediated DNA damage to tumor cell killing

Mitotic regulators BuGZ and Bub3 play a critical role in RNA splicing during interphase, and disruption of this function leads to R-loop formation, DNA damage, and p53 activation.

Although studies suggest that perturbing mitotic progression leads to DNA damage and p53 activation, which in turn lead to either cell apoptosis or senescence, it remains unclear how mitotic defects trigger p53 activation. We show that BuGZ and Bub3, which are two mitotic regulators localized in the interphase nucleus, interact with the splicing machinery and are required for pre-mRNA splicing. Similar to inhibition of RNA splicing by pladienolide B, depletion of either BuGZ or Bub3 led to increased formation of RNA–DNA hybrids (R-loops), which led to DNA damage and p53 activation in both human tumor cells and primary cells. Thus, R-loop–mediated DNA damage and p53 activation offer a mechanistic explanation for apoptosis of cancer cells and senescence of primary cells upon disruption of the dual-function mitotic regulators. This demonstrates the importance of understanding the full range of functions of mitotic regulators to develop antitumor drugs.

(+)‑Terrein inhibits human hepatoma Bel‑7402 proliferation through cell cycle arrest

Hepatoma is a common malignant tumor. Thus, the development of a high‑efficacy therapeutic drug for hepatoma is required. In this study, (+)‑terrein isolated from the marine sponge‑derived Aspergillus terreus PF‑26 against cell growth, apoptosis and cell cycle were assessed by MTT and flow cytometry. mRNA array containing 73 cell cycle‑related genes and three cell morphology‑related genes was generated and its performance evaluated. The cell cycle pathway map was created using the pathview package. The results showed that (+)‑terrein inhibited the growth of Bel‑7402 cells with alterations in cell morphology and a reduced transcript expression of cell morphology genes (fibronectin, N‑cadherin, and vimentin). In addition, flow cytometric analysis revealed that (+)‑terrein arrested the Bel‑7402 cell cycle without inducing apoptosis. Based on multiple mRNA analysis, the downregulated expression of the CCND2, CCNE2, CDKN1C, CDKN2B, ANAPC, PKMYT1, CHEK2 and PCNA genes was observed in 10 µM (+)‑terrein‑treated Bel‑7402 cells (>2‑fold and P≤0.05), compared with the controls. Thus, the antiprolife-rative mechanism of (+)‑terrein against Bel‑7402 cells may be due to the cell cycle arrest by blocking cell cycle gene expression and changing cell morphology.

Terrein biosynthesis in Aspergillus terreus and its impact on phytotoxicity

Terrein is a fungal metabolite with ecological, antimicrobial, antiproliferative, and antioxidative activities. Although it is produced by Aspergillus terreus as one of its major secondary metabolites, not much is known about its biosynthetic pathway. Here, we describe an unexpected discovery of the terrein biosynthesis gene locus made while we were looking for a PKS gene involved in production of conidia coloration pigments common for Aspergilli. The gene, ATEG_00145, here named terA, is essential for terrein biosynthesis and heterologous production of TerA in Aspergillus niger revealed an unusual plasticity in the products formed, yielding a mixture of 4-hydroxy-6-methylpyranone, orsellinic acid, and 6,7-dihydroxymellein. Biochemical and molecular genetic analyses indicate a low extension cycle specificity of TerA. Furthermore, 6-hydroxymellein was identified as a key intermediate in terrein biosynthesis. We find that terrein production is highly induced on plant-derived media, that terrein has phytotoxic activity on plant growth, and induces lesions on fruit surfaces.

High expression of octamer transcription factor 1 in cervical cancer

Cervical carcinoma is the second most prevalent malignancy in females worldwide. The crucial etiologic factors involved in the development of cervical carcinoma include infection with papillomavirus, and the structural or functional mutation of oncogenes and tumor suppressor genes. The abnormal change of octamer transcription factor 1 (OCT1) is associated with tumor progression and a poor patient survival rate. However, little is known regarding the effect of OCT1 in cervical cancer. In the present study, flow cytometry, western blot analysis and quantitative polymerase chain reaction (qPCR) were peformed to identify differentially expressed OCT1 in cervical cancer tissue and adjacent non-cancerous tissues. The normalized OCT1 gene expression in cervical cancer was 5.98 times higher compared with the adjacent non-cancerous tissues. Western blot analysis and flow cytometry assessed the levels of OCT1 protein. The results of these two differential techniques showed that the protein expression level of OCT1 was greater in cervical cancer tissues, which corresponded with the qPCR results. Finally, as OCT1 is a potential target gene for microRNA (miR)-1467, -1185, -4493 and -3919, their expression levels were analyzed in cervical cancer tissues and adjacent non-cancerous tissues; they were downregulated by ~45% in the cervical cancer samples. The results of the present study showed that OCT1 is highly expressed in cervical cancer tissues and indicated that OCT-1 may be significant in cervical cancer.