A marine anthraquinone SZ-685C overrides adriamycin-resistance in breast cancer cells through suppressing Akt signaling

Unleashing the potential of Genistein and its derivatives as effective therapeutic agents for breast cancer treatment

Breast cancer remains one of the leading causes of cancer-related deaths among women worldwide. Genistein (Gen), a phytoestrogen soy isoflavone, has emerged as a promising agent in the prevention and treatment of breast cancer due to its ability to function as a natural selective estrogen receptor modulator (SERM). This review explores the multifaceted mechanisms through which Gen and its derivatives exert their anticancer effects, including modulation of the PI3K/Akt signaling pathway, regulation of apoptosis, inhibition of angiogenesis, and impacts on DNA methylation and enzyme functions. We discuss the dual roles of Gen in both enhancing and inhibiting estrogen receptor (ER)-dependent pathways., highlighting its complex interactions with ERα and ERβ. Furthermore, the review examines the synergistic effect of combining Gen with conventional chemotherapeutic agents such as doxorubicin, cisplatin, and selenium, as well as other natural compounds like lycopene. Clinical studies suggest that while isoflavones may not significantly influence breast cancer progression in general, the high consumption of soy isoflavones is associated with reduced recurrence rates in breast cancer survivors. Importantly, Gen's ability to modulate key signaling pathways and enhance the efficacy of existing treatments improves its potential as a valuable adjunct in breast cancer therapy. In conclusion, Gen and its derivatives offer a novel and promising approach for treatment of breast cancer. Continued research into their mechanisms of action and clinical applications will be essential in optimizing their therapeutic potential and translating these findings into effective clinical interventions.

SZ-685C inhibits the growth of non-functioning pituitary adenoma by down-regulating miR-340-3p and inducing autophagy

Background

SZ-685C, an anthracycline compound derived from the mangrove endophytic fungus Halorosellinia sp. (No. 1403) collected from the South China Sea, has shown strong anticancer activities. Non-functioning pituitary adenomas (NFPAs) are a type of tumor that can be challenging to manage clinically and have a significant unmet medical need. Our research has found that SZ-685C showed an inhibitory effect on the viability, migration ability, and proliferation ability of a human non-functioning pituitary tumor-derived folliculostellate (PDFS) cell line.

Methods

SZ-685C was prepared and purified from the mangrove endophytic fungus No. 1403. PDFS cells were exposed to SZ-685C, and the effect of SZ-685C on PDFS cells was evaluated. RNA sequencing was used to analyze the miRNA expression profile in PDFS cells of the control group and SZ-685C-treated group. Quantitative polymerase chain reaction (qPCR) was performed to verify the expression of selected miR-340-3p. The effects of SZ-685C on PDFS cells after overexpression of miR-340-3p were evaluated. Dual-luciferase reporter assays showed PPP1CB is a direct target of miR-340-3p. Finally, the action pathway of the selected miR-340-3p was predicted and evaluated through bioinformatics analysis.

Results

SZ-685C reduced cell viability in PDFS cells, accompanied by inhibition of migration ability and proliferation ability. The IC50 value for 24 h is 9.144 ± 0.991 μM, and for 48 h is 4.635 ± 0.551 μM. SZ-685C increased the protein levels of Beclin 1, the ratio of LC3-II to LC3-I, and LAMP-1, and down-regulated p62. MiRNA sequencing and further validation showed that miR-340-3p significantly decreased in PDFS cells treated with SZ-685C. After overexpression of miR-340-3p, the inhibition of viability, migration ability, proliferation ability, and autophagy-promoting effect of SZ-685C on PDFS cells were weakened. SZ-685C caused a decrease in PPP1CB expression and activation of the ERK pathway in PDFS cells, and this trend was reversed after overexpression of miR-340-3p.

Conclusions

SZ-685C downregulates the expression of miR-340-3p in PDFS cells, thereby reducing the expression of PPP1CB and activating the ERK pathway to promote autophagic cell death, leading to inhibition of PDFS cell growth.

Using nanotechnology to progress the utilization of marine natural products in combating multidrug resistance in cancer: A prospective strategy

Achieving targeted, customized, and combination therapies with clarity of the involved molecular pathways is crucial in the treatment as well as overcoming multidrug resistance (MDR) in cancer. Nanotechnology has emerged as an innovative and promising approach to address the problem of drug resistance. Developing nano-formulation-based therapies using therapeutic agents poses a synergistic effect to overcome MDR in cancer. In this review, we aimed to highlight the important pathways involved in the progression of MDR in cancer mediated through nanotechnology-based approaches that have been employed to circumvent them in recent years. Here, we also discussed the potential use of marine metabolites to treat MDR in cancer, utilizing active drug-targeting nanomedicine-based techniques to enhance selective drug accumulation in cancer cells. The discussion also provides future insights for developing complex targeted, multistage responsive nanomedical drug delivery systems for effective cancer treatments. We propose more combinational studies and their validation for the possible marine-based nanoformulations for future development.

Chemical diversity, medicinal potentialities, biosynthesis, and pharmacokinetics of anthraquinones and their congeners derived from marine fungi: a comprehensive update

Marine fungi receive excessive attention as prolific producers of structurally unique secondary metabolites, offering promising potential as substitutes or conjugates for current therapeutics, whereas existing research has only scratched the surface in terms of secondary metabolite diversity and potential industrial applications as only a small share of bioactive natural products have been identified from marine-derived fungi thus far. Anthraquinones derived from filamentous fungi are a distinct large group of polyketides containing compounds which feature a common 9,10-dioxoanthracene core, while their derivatives are generated through enzymatic reactions such as methylation, oxidation, or dimerization to produce a large variety of anthraquinone derivatives. A considerable number of reported anthraquinones and their derivatives have shown significant biological activities as well as highly economical, commercial, and biomedical potentialities such as anticancer, antimicrobial, antioxidant, and anti-inflammatory activities. Accordingly, and in this context, this review comprehensively covers the state-of-art over 20 years of about 208 structurally diverse anthraquinones and their derivatives isolated from different species of marine-derived fungal genera along with their reported bioactivity wherever applicable. Also, in this manuscript, we will present in brief recent insights centred on their experimentally proved biosynthetic routes. Moreover, all reported compounds were extensively investigated for their in-silico drug-likeness and pharmacokinetics properties which intriguingly highlighted a list of 20 anthraquinone-containing compounds that could be considered as potential drug lead scaffolds.

Extremophilic Fungi from Marine Environments: Underexplored Sources of Antitumor, Anti-Infective and Other Biologically Active Agents

Marine environments are underexplored terrains containing fungi that produce a diversity of natural products given unique environmental pressures and nutrients. While bacteria are commonly the most studied microorganism for natural products in the marine world, marine fungi are also abundant but remain an untapped source of bioactive metabolites. Given that their terrestrial counterparts have been a source of many blockbuster antitumor agents and anti-infectives, including camptothecin, the penicillins, and cyclosporin A, marine fungi also have the potential to produce new chemical scaffolds as leads to potential drugs. Fungi are more phylogenetically diverse than bacteria and have larger genomes that contain many silent biosynthetic gene clusters involved in making bioactive compounds. However, less than 5% of all known fungi have been cultivated under standard laboratory conditions. While the number of reported natural products from marine fungi is steadily increasing, their number is still significantly lower compared to those reported from their bacterial counterparts. Herein, we discuss many varied cytotoxic and anti-infective fungal metabolites isolated from extreme marine environments, including symbiotic associations as well as extreme pressures, temperatures, salinity, and light. We also discuss cultivation strategies that can be used to produce new bioactive metabolites or increase their production. This review presents a large number of reported structures though, at times, only a few of a large number of related structures are shown.

Secondary metabolites from mangrove-associated fungi: source, chemistry and bioactivities

Covering 1989 to 2020The mangrove forests are a complex ecosystem occurring at tropical and subtropical intertidal estuarine zones and nourish a diverse group of microorganisms including fungi, actinomycetes, bacteria, cyanobacteria, algae, and protozoa. Among the mangrove microbial community, mangrove associated fungi, as the second-largest ecological group of the marine fungi, not only play an essential role in creating and maintaining this biosphere but also represent a rich source of structurally unique and diverse bioactive secondary metabolites, attracting significant attention of organic chemists and pharmacologists. This review summarizes the discovery relating to the source and characteristics of metabolic products isolated from mangrove-associated fungi over the past thirty years (1989-2020). Its emphasis included 1387 new metabolites from 451 papers, focusing on bioactivity and the unique chemical diversity of these natural products.

Marine Anthraquinones: Pharmacological and Toxicological Issues

The marine ecosystem, populated by a myriad of animals, plants, and microorganisms, is an inexhaustible reservoir of pharmacologically active molecules. Among the multiple secondary metabolites produced by marine sources, there are anthraquinones and their derivatives. Besides being mainly known to be produced by terrestrial species, even marine organisms and the uncountable kingdom of marine microorganisms biosynthesize anthraquinones. Anthraquinones possess many different biological activities, including a remarkable antitumor activity. However, due to their peculiar chemical structures, anthraquinones are often associated with toxicological issues, even relevant, such as genotoxicity and mutagenicity. The aim of this review is to critically describe the anticancer potential of anthraquinones derived from marine sources and their genotoxic and mutagenic potential. Marine-derived anthraquinones show a promising anticancer potential, although clinical studies are missing. Additionally, an in-depth investigation of their toxicological profile is needed before advocating anthraquinones as a therapeutic armamentarium in the oncological area.

Marine compounds targeting the PI3K/Akt signaling pathway in cancer therapy

Cancer is a disease characterized by overproliferation, including that due to transformation, apoptosis disorders, proliferation, invasion, angiogenesis and metastasis, and is one of the deadliest diseases. Currently, conservative chemotherapy is used for cancer treatment due to a lack of effective drugs. The PI3K/Akt signaling pathway plays a very essential role in the pathogenesis of many cancers, and abnormal activation of this pathway leads to abnormal expression of a series of downstream proteins, which ultimately results in the excessive proliferation of cancer cells. Therefore, the PI3K/Akt signaling pathway is a critical target in cancer treatment. Marine drugs have attracted much attention in recent years, and studies have found that many extracts from oceanic animals, plants and microorganisms or their metabolites exert antitumor effects, including antiproliferative effects or the induction of cell cycle arrest, apoptosis or autophagy. However, most anticancer targets and the mechanisms of marine compounds remain unclear. The great potential of the development of marine drugs provides a new direction for cancer treatment. This review focuses on marine compounds that target the PI3K/Akt signaling pathway for the prevention and treatment of cancer and provides comprehensive information for those interested in research on marine drugs.

Bioactivities and Structure-Activity Relationships of Natural Tetrahydroanthraquinone Compounds: A Review

Tetrahydroanthraquinones are a kind of important microbial secondary metabolites with promising biological activities. Most of them were found in microorganisms, a few were derived from Chinese herbal medicine. In this review, aiming to provide basis for the further research and development of tetrahydroanthraquinone compounds, we summarized the physiological activities of natural tetrahydroanthraquinone compounds, including anti-cancer, anti-microbial, and antidiabetic activities. The source, structure, and action mechanisms of active tetrahydroanthraquinones are described in detail. Furthermore, this review firstly analyzed the structure–activity relationship of tetrahydroanthraquinones. Our study will serve as a valuable guideline for further research on the structural optimization, mechanism study, and development of tetrahydroanthraquinone as novel drugs. Aiming to provide references for further studies and development of tetrahydroanthraquinone compounds.

Tumour-associated macrophages as a novel target of VEGI-251 in cancer therapy

Tumour‐associated macrophages (TAMs), which possess M2‐like characters and are derived from immature monocytes in the circulatory system, represent a predominant population of inflammatory cells in solid tumours. TAM infiltration in tumour microenvironment can be used as an important prognostic marker in many cancer types and is a potential target for cancer prevention or treatment. VEGI‐251 not only is involved in the inhibition of tumour angiogenesis, but also participates in the regulation of host immunity. This work aimed to investigate the involvement of VEGI‐251 in the regulation of specific antitumour immunity. We found that recombinant human VEGI‐251(rhVEGI‐251) efficiently mediated the elimination of TAMs in tumour tissue in mice, and induced apoptosis of purified TAMs in vitro. During this process, caspase‐8 and caspase‐3 were activated, leading to PARP cleavage and apoptosis. Most importantly, we further elucidated the mechanism underlying VEGI‐251‐triggered TAM apoptosis, which suggests that ASK1, an intermediate component of the VEGI‐251, activates the JNK pathway via TRAF2 in a potentially DR3‐dependent manner in the process of TAM apoptosis. Collectively, our findings provide new insights into the basic mechanisms underlying the actions of VEGI‐251 that might lead to future development of antitumour therapeutic strategies using VEGI‐251 to target TAMs.

Fungal Pigments: Potential Coloring Compounds for Wide Ranging Applications in Textile Dyeing

Synthetic pigments/non-renewable coloring sources used normally in the textile industry release toxic substances into the environment, causing perilous ecological challenges. To be safer from such challenges of synthetic colorants, academia and industries have explored the use of natural colorants such as microbial pigments. Such explorations have created a fervent interest among textile stakeholders to undertake the dyeing of textile fabrics, especially with fungal pigments. The biodegradable and sustainable production of natural colorants from fungal sources stand as being comparatively advantageous to synthetic dyes. The prospective scope of fungal pigments has emerged in the opening of many new avenues in textile colorants for wide ranging applications. Applying the biotechnological processes, fungal pigments like carotenoids, melanins, flavins, phenazines, quinones, monascins, violacein, indigo, etc. could be extracted on an industrial scale. This review appraises the studies and applications of various fungal pigments in dyeing textile fabrics and is furthermore shedding light on the importance of toxicity testing, genetic manipulations of fungal pigments, and their future perspectives under biotechnological approaches.

Differential Characterization of Temozolomide-Resistant Human Glioma Cells

Glioblastoma multiforme (GBM) is the most common type of primary and malignant tumor occurring in the adult central nervous system. Temozolomide (TMZ) has been considered to be one of the most effective chemotherapeutic agents to prolong the survival of patients with glioblastoma. Many glioma cells develop drug-resistance against TMZ that is mediated by increasing O-6-methylguanine-DNA methyltransferase (MGMT) levels. The expression of connexin 43 was increased in the resistant U251 subline compared with the parental U251 cells. The expression of epithelial-mesenchymal transition (EMT)-associated regulators, including vimentin, N-cadherin, and β-catenin, was reduced in the resistant U251 subline. In addition, the resistant U251 subline exhibited decreased cell migratory activity and monocyte adhesion ability compared to the parental U251 cells. Furthermore, the resistant U251 subline also expressed lower levels of vascular cell adhesion molecule (VCAM)-1 after treatment with recombinant tumor necrosis factor (TNF)-α. These findings suggest differential characteristics in the drug-resistant GBM from the parental glioma cells.

Harzianumnones A and B: two hydroxyanthraquinones from the coral-derived fungusTrichoderma harzianum

Two new hydroxyanthraquinones, harzianumnones A (1) and B (2), together with seven known analogs (3–9), were isolated from the soft coral-derived fungus Trichoderma harzianum (XS-20090075). Their chemical structures were elucidated by extensive spectroscopic investigation. The absolute configurations of 1 and 2 were determined by ECD calculation and single-crystal X-ray diffraction. Compounds 1 and 2 were identified as a pair of epimers, which are the first example of hydroanthraquinones from T. harzianum. Compounds 7 and 8 exhibited cytotoxicity against hepatoma cell line HepG2 with IC₅₀ values of 2.10 and 9.39 μM, respectively. Compound 7 was still found to show cytotoxicity against cervical cancer cell line HeLa with an IC₅₀ value of 8.59 μM.

Two new hydroxyanthraquinones were isolated from the soft coral-derived fungus Trichoderma harzianum, which are the first examples of hydroanthraquinones from T. harzianum.

Regulation of different polyketide biosynthesis by green light in an endophytic fungus of mangrove leaf

Light is an important environmental signal for many organisms. The light response reports of fungi usually focus on blue light and red light. Although the green light sensor has also been found in several fungi, the knowledge of the green light response in fungi is very limited. Halorosellinia sp. (No. 1403) is a light-sensitive endophytic fungus of mangrove leaf. In this study, we explored the specific effects of monochromatic blue light, red light, and green light on polyketides biosynthesis in Halorosellinia sp. (No. 1403), respectively. The major polyketides produced in Halorosellinia sp. (No. 1403) are octaketides (1403C and 1403R) and heptaketide (griseofulvin). All monochromatic light enhanced octaketide biosynthesis and inhibited heptaketide biosynthesis to some extent compared with the dark condition. Most prominently, the total production of octaketides was increased by 76%, and the production of heptaketide was decreased by 73% under green light in bioreactor. Therefore, green light can not only influence the secondary metabolism in fungi, but also it can influence different biosynthetic pathways in different ways. We speculate that the significant effect of green light on mangrove leaf endophytic fungus Halorosellinia sp. (No. 1403) may be a kind of environmental adaptation to plant photosynthesis.

A Fast and Efficient Replacement of CTAB with MUA on the Surface of Gold Nanorods Assisted by a Water-Immiscible Ionic Liquid

The synthesis and surface modification of gold nanorods (GNRs) is one of the most important and basic issues in nanoscience. Most of the widely investigated GNRs are coated with a cetyltrimethylammonium bromide(CTAB) bilayer. Here, a highly efficient method is proposed to replace CTAB from the surface of GNRs with a bifunctional 11-mercaptoundecanoic acid in order to decrease the possible toxicity caused by CTAB. This ligand exchange is achieved in a biphasic mixture of an aqueous solution and a water-immiscible ionic liquid (IL), [BMIM][Tf₂ N]. That is, by mixing IL, mercaptoundecanoic acid (MUA)/IL (200 × 10^-3 m) and a concentrated aqueous solution of GNRs together, followed by vortex stirring for 90 s, CTAB-capped GNRs with varying aspect ratios can be turned into corresponding MUA-capped GNRs with the same aspect ratio. Furthermore, the formed MUA-capped GNRs can be obtained in a large quantity and stored as powders for easy use. The MUA-capped GNRs with improved biocompatibility and colloidal stability are well suited for further biological functionalization and potential applications. This IL-assisted ligand exchange can reverse the surface charge, enhance the stability of GNRs, and suppress its cytotoxicity.

Endophytic fungi from mangrove inhibit lung cancer cell growth and angiogenesis in vitro

The secondary metabolites of mangrove-derived endophytic fungi contain multiple substances with novel structures and biological activities. In the present study, three types of mangrove plants, namely Kandelia candel, Rhizophora stylosa and Rhizophoraceae from Zhanjiang region including the leaves, roots and stems were collected, and endophytic fungi were isolated, purified and identified from these mangrove plants. MTT assay was used to observe the effects of the isolated endophytic fungi on the growth of A549 and NCI-H460 lung cancer cells. The effect of the endophytic fungi on lung cancer angiogenesis in vitro induced by the HPV-16 E7 oncoprotein was observed. Our results showed that 28 strains of endophytic fungi were isolated, purified and identified from the three types of mangrove plants. Ten strains of endophytic fungi significantly suppressed the growth of A549 and NCI-H460 cells. The average inhibitory rates in the A549 cells were 64.4, 59.5, 81.9, 43.9, 58.3, 56.2, 48.3, 42.4, 93.0 and 49.7%, respectively. The average inhibitory rates in the NCI-H460 cells were 41.2, 49.3, 82.7, 40.7, 53.9, 52.6, 56.8, 64.3, 91.0 and 45.6%, respectively. Particularly, three strains of endophytic fungi markedly inhibited HPV-16 E7 oncoprotein‑induced lung cancer angiogenesis in vitro. These findings contribute to the further screening of potential chemotherapeutic agents from mangrove-derived endophytic fungi.

Cytotoxic and Antibacterial Preussomerins from the Mangrove Endophytic Fungus Lasiodiplodia theobromae ZJ-HQ1

Two new chlorinated preussomerins, chloropreussomerins A and B (1 and 2), together with nine known preussomerin analogues, 3-11, were obtained from the endophytic fungus Lasiodiplodia theobromae ZJ-HQ1. Their structures were elucidated by a combination of spectroscopic analyses. The absolute configurations of 1 and 2 were both determined by single-crystal X-ray diffraction using Cu Kα radiation. Chloropreussomerins A and B (1 and 2) are the first chlorinated compounds in the preussomerin family, and preussomerin M (3) is reported for the first time as a natural product. Compounds 1 and 2 showed potent in vitro cytotoxicity against A549 and MCF-7 human cancer cell lines, with IC50 values ranging from 5.9 to 8.9 μM, and compounds 4-7 exhibited significant bioactivity against A549, HepG2, and MCF-7 human cancer cell lines, with IC50 values of 2.5-9.4 μM. In the antibacterial assay, compounds 1, 2, 5-7, and 11 exhibited significant activities against Staphylococcus aureus, with MIC values between 1.6 and 13 μg/mL.

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities

Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s) due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi's productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.

Tetrahydroanthraquinone Derivative (±)-4-Deoxyaustrocortilutein Induces Cell Cycle Arrest and Apoptosis in Melanoma Cells via Upregulation of p21 and p53 and Downregulation of NF-kappaB

BACKGROUND

Malignant melanoma is an aggressive type of skin cancer with high risk for metastasis and chemoresistance. Disruption of tightly regulated processes such as cell cycle, cell adhesion, cell differentiation and cell death are predominant in melanoma development. So far, conventional treatment options have been insufficient to treat metastatic melanoma and survival rates are poor. Anthraquinone compounds have been reported to have anti-tumorigenic potential by DNA-interaction, promotion of apoptosis and suppression of proliferation in various cancer cells.

METHODS

In the current study, the racemic tetrahydroanthraquinone derivative (±)-4-deoxyaustrocortilutein (4-DACL) was synthesized and the cytotoxic activity against melanoma cells and melanoma spheroids determined by CellTiter-Blue viability Assay and phase contrast microscopy. Generation of reactive oxygen species (ROS) was determined with CellROX Green and Deep Red Reagent kit and microplate-based fluorometry. Luciferase reporter gene assays for nuclear factor kappa B (NF-κB) and p53 activities and western blotting analysis were carried out to detect the expression of anti-proliferative or pro-apoptotic (p53, p21, p27, MDM2, and GADD45M) and anti-apoptotic (p65, IκB-α, IKK) proteins. Cell cycle distribution and apoptosis rate were detected by flow cytometry, the morphological changes visualized by fluorescence microscopy and the activation of different caspase cascades distinguished by Caspase Glo 3/7, 8 and 9 Assays.

RESULTS

We demonstrated that 4-DACL displayed high activity against different malignant melanoma cells and melanoma spheroids and only low toxicity to melanocytes and other primary cells. In particular, 4-DACL treatment induced mitochondrial ROS, reduced NF-κB signaling activity and increased up-regulation of the cell cycle inhibitors cyclin-dependent kinase inhibitor p21 (p21(WAF1/Cip1)) and the tumor suppressor protein p53 in a dose-dependent manner, which was accompanied by decreased cell proliferation and apoptosis via the intrinsic pathway.

CONCLUSION

According to these results, we suggest that 4-DACL may be a promising therapeutic agent for the treatment of malignant melanoma.

MicroRNA181a Is Overexpressed in T-Cell Leukemia/Lymphoma and Related to Chemoresistance

MicroRNAs (miRs) play an important role in tumorogenesis and chemoresistance in lymphoid malignancies. Comparing with reactive hyperplasia, miR181a was overexpressed in 130 patients with T-cell leukemia/lymphoma, including acute T-cell lymphoblastic leukemia (n = 32), T-cell lymphoblastic lymphoma (n = 16), peripheral T-cell lymphoma, not otherwise specified (n = 45), anaplastic large cell lymphoma (n = 15), and angioimmunoblastic T-cell lymphoma (n = 22). Irrespective to histological subtypes, miR181a overexpression was associated with increased AKT phosphorylation. In vitro, ectopic expression of miR181a in HEK-293T cells significantly enhanced cell proliferation, activated AKT, and conferred cell resistance to doxorubicin. Meanwhile, miR181a expression was upregulated in Jurkat cells, along with AKT activation, during exposure to chemotherapeutic agents regularly applied to T-cell leukemia/lymphoma treatment, such as doxorubicin, cyclophosphamide, cytarabine, and cisplatin. Isogenic doxorubicin-resistant Jurkat and H9 cells were subsequently developed, which also presented with miR181a overexpression and cross-resistance to cyclophosphamide and cisplatin. Meanwhile, specific inhibition of miR181a enhanced Jurkat and H9 cell sensitivity to chemotherapeutic agents, further indicating that miR181a was involved in acquired chemoresistance. Collectively, miR181a functioned as a biomarker of T-cell leukemia/lymphoma through modulation of AKT pathway. Related to tumor cell chemoresistance, miR181a could be a potential therapeutic target in treating T-cell malignancies.

Can Some Marine-Derived Fungal Metabolites Become Actual Anticancer Agents?

Marine fungi are known to produce structurally unique secondary metabolites, and more than 1000 marine fungal-derived metabolites have already been reported. Despite the absence of marine fungal-derived metabolites in the current clinical pipeline, dozens of them have been classified as potential chemotherapy candidates because of their anticancer activity. Over the last decade, several comprehensive reviews have covered the potential anticancer activity of marine fungal-derived metabolites. However, these reviews consider the term "cytotoxicity" to be synonymous with "anticancer agent", which is not actually true. Indeed, a cytotoxic compound is by definition a poisonous compound. To become a potential anticancer agent, a cytotoxic compound must at least display (i) selectivity between normal and cancer cells (ii) activity against multidrug-resistant (MDR) cancer cells; and (iii) a preferentially non-apoptotic cell death mechanism, as it is now well known that a high proportion of cancer cells that resist chemotherapy are in fact apoptosis-resistant cancer cells against which pro-apoptotic drugs have more than limited efficacy. The present review thus focuses on the cytotoxic marine fungal-derived metabolites whose ability to kill cancer cells has been reported in the literature. Particular attention is paid to the compounds that kill cancer cells through non-apoptotic cell death mechanisms.

Gambogenic acid alters chemosensitivity of breast cancer cells to Adriamycin

Background

Breast cancer remains a major health problem worldwide, and is becoming increasingly resistant to traditional drug treatments. For instance, Adriamycin (ADR) is beneficial for the treatment of breast cancer. However, its wide application often leads to drug resistance in clinic practice, which results in treatment failure. Gambogenic acid (GNA), a polyprenylated xanthone isolated from the traditional medicine gamboge, has been reported to effectively inhibit the survival and proliferation of cancer cells. Its effects on ADR resistance have not yet been reported in breast cancer. In this study, we examined the ability of GNA to modulate ADR resiatance and the molecular mechanisms underlying this process using a cell based in vitro system.

Methods

An MTT assay was used to evaluate the inhibitory effect of the drugs on the growth of MCF-7 and MCF-7/ADR cell lines. The effects of drugs on apoptosis were detected using Annexin-V APC/7-AAD double staining. The expression of apoptosis-related proteins and the proteins in the PTEN/PI3K/AKT pathway were evaluated by Western blot analysis.

Results

In the MCF-7/ADR cell lines, the IC50 (half maximal inhibitory concentration) of the group that received combined treatment with GNA and ADR was significantly lower than that in the ADR group, and this value decreased with an increasing concentration of GNA. In parallel, GNA treatment increased the chemosensitivity of breast cancer cells to ADR. The cell apoptosis and cell cycle anaysis indicated that the anti-proliferative effect of GNA is in virtue of increased G0/G1 arrest and potentiated apoptosis. When combined with GNA in MCF-7/ADR cell lines, the expression levels of the tumor suppressor gene PTEN (phosphatase and tensin homolog deleted on chromosome ten) and the apoptosis-related proteins caspase-3 and capsese-9 were significantly increased, while the expression of phosphorylated AKT was decreased.

Conclusions

Our study has indicated a potential role for GNA to increase the chemosensitivity of breast cancer cells to ADR. This modulatory role was mediated by suppression of the PTEN/PI3K/AKT pathway that led to apoptosis in MCF-7/ADR cells. This work suggests that GNA may be used as a regulatory agent for treating ADR resistance in breast cancer patients.

A Survey of Marine Natural Compounds and Their Derivatives with Anti-cancer Activity Reported in 2012

Although considerable effort and progress has been made in the search for new anticancer drugs and treatments in the last several decades, cancer remains a major public health problem and one of the major causes of death worldwide. Many sources, including plants, animals, and minerals, are of interest in cancer research because of the possibility of identifying novel molecular therapeutics. Moreover, structure-activity-relationship (SAR) investigations have become a common way to develop naturally derived or semi-synthetic molecular analogues with improved efficacy and decreased toxicity. In 2012, approximately 138 molecules from marine sources, including isolated compounds and their associated analogues, were shown to be promising anticancer drugs. Among these, 62% are novel compounds. In this report, we review the marine compounds identified in 2012 that may serve as novel anticancer drugs.

The marine metabolite SZ-685C induces apoptosis in primary human nonfunctioning pituitary adenoma cells by inhibition of the Akt pathway in vitro

Nonfunctioning pituitary adenoma (NFPA) is one of the most common types of pituitary adenoma. The marine anthraquinone derivative SZ-685C has been isolated from the secondary metabolites of the mangrove endophytic fungus Halorosellinia sp. (No. 1403) which is found in the South China Sea. Recent research has shown that SZ-685C possesses anticancer and tumor suppressive effects. The tetrazolium-based colorimetric assay (MTT assay) to investigate the different effect of the marine compound SZ-685C on the proliferation of primary human NFPA cells, rat normal pituitary cells (RPCs) and rat prolactinoma MMQ cell lines. Hoechst 33342 dye/propidium iodide (PI) double staining and fluorescein isothiocyanate-conjugated Annexin V/PI (Annexin V-FITC/PI) apoptosis assays detected an enhanced rate of apoptosis in cells treated with SZ-685C. Enhanced expression levels of caspase 3 and phosphate and tensin homolog (PTEN) were determined by Western blotting. Notably, the protein expression levels of Akt were decreased when the primary human NFPA cells were treated with SZ-685C. Here, we show that SZ-685C induces apoptosis of human NFPA cells through inhibition of the Akt pathway in vitro. The understanding of apoptosis has provided the basis for novel targeted therapies that can induce death in cancer cells or sensitize them to established cytotoxic agents and radiation therapy.

Anthraquinone G503 induces apoptosis in gastric cancer cells through the mitochondrial pathway

G503 is an anthraquinone compound isolated from the secondary metabolites of a mangrove endophytic fungus from the South China Sea. The present study elucidates the anti-tumor activity and the underlying mechanism of G503. Cell viability assay performed in nine cancer cell lines and two normal cell lines demonstrated that the gastric cancer cell line SGC7901 is the most G503-sensitive cancer cells. G503 induced SGC7901 cell death via apoptosis. G503 exposure activated caspases-3, -8 and -9. Pretreatment with the pan-caspase inhibitor Z-VAD-FMK and caspase-9 inhibitor Z-LEHD-FMK, but not caspase-8 inbibitor Z-IETD-FMK, attenuated the effect of G503. These results suggested that the intrinsic mitochondrial apoptosis pathway, rather than the extrinsic pathway, was involved in G503-induced apoptosis. Furthermore, G503 increased the ratio of Bax to Bcl-2 in the mitochondria and decreased the ratio in the cytosol. G503 treatment resulted in mitochondrial depolarization, cytochrome c release and the subsequent cleavage of caspase -9 and -3. Moreover, it is reported that the endoplasmic reticulum apoptosis pathway may also be activated by G503 by inducing capase-4 cleavage. In consideration of the lower 50% inhibitory concentration for gastric cancer cells, G503 may serve as a promising candidate for gastric cancer chemotherapy.

Advances in the study of the structures and bioactivities of metabolites isolated from mangrove-derived fungi in the South China Sea

Many metabolites with novel structures and biological activities have been isolated from the mangrove fungi in the South China Sea, such as anthracenediones, xyloketals, sesquiterpenoids, chromones, lactones, coumarins and isocoumarin derivatives, xanthones, and peroxides. Some compounds have anticancer, antibacterial, antifungal and antiviral properties, but the biosynthesis of these compounds is still limited. This review summarizes the advances in the study of secondary metabolites from the mangrove-derived fungi in the South China Sea, and their biological activities reported between 2008 and mid-2013.

SZ-685C exhibits potent anticancer activity in both radiosensitive and radioresistant NPC cells through the miR-205-PTEN-Akt pathway

Radioresistance is a major obstacle to the treatment of human nasopharyngeal carcinoma (NPC). Emerging evidence has demonstrated that miRNAs are involved in cancer therapy resistance. Our research group established the radioresistant NPC cell line CNE2R derived from the CNE2 cell line, and demonstrated that irradiation-induced miR-205 determined the resistance of NPC through directly targeting PTEN. However, specific inhibitors targeting miRNAs are largely undetermined. SZ-685C was expected to abrogate the radioresistance of CNE2 cells through the miR-205‑PTEN-Akt pathway. SZ-685C exhibited a similar cytotoxic effect on both cell lines, and we demonstrated that both intrinsic and extrinsic pathways were activated by SZ-685C in the cell lines. Importantly, the miR-205-PTEN-Akt pathway was the key cell signaling pathway activated in the CNE2R cells upon SZ-685C treatment; however, the Stat3-Jab1-p27 pathway might participate in the pro-apoptotic effect in CNE2 cells but not in CNE2R cells. SZ-685C is a promising anticancer agent for treatment of NPC, and it exhibited pro-apoptotic activity in both radiosensitive and radioresistant NPC cells. Although the mechanisms between the two cell lines were not identical, the pro-apoptotic effects were similar between the two cell lines.