Hispolon induces apoptosis through JNK1/2-mediated activation of a caspase-8, -9, and -3-dependent pathway in acute myeloid leukemia (AML) cells and inhibits AML xenograft tumor growth in vivo

Initial report on the multiple biological and pharmacological properties of hispolon: Exploring stochastic mechanisms

The development of natural substances derived from nature poses a significant challenge as technologies for the extraction and characterization of active principles advance. Hispolon has received a lot of attention in recent years, ascribable to its wide range of biological activities. It is a phenolic molecule that was extracted from several mushroom species such as Phellinus igniarius, Phellinus linteus, Phellinus lonicerinus, Phellinus merrillii, and Inonotus hispidus. To provide a comprehensive overview of the pharmacological activities of hispolon, this review highlights its anticancer, anti-inflammatory, antioxidant, antibacterial, and anti-diabetic activities. Several scientific research databases, including Google Scholar, Web of Science, PubMed, SciFinder, SpringerLink, Science Direct, Scopus, and, Wiley Online were used to gather the data on hispolon until May 2024. The in vitro and in vivo studies have revealed that hispolon exhibited significant anticancer properties through modifying several signaling pathways including cell apoptosis, cycle arrest, autophagy, and inhibition of angiogenesis and metastasis. Hispolon's antimicrobial activity was proven against many bacterial, fungal, and viral pathogens, highlighting its potential use as a novel antimicrobial agent. Additionally, hispolon displayed potent anti-inflammatory activity through the suppression of key inflammatory mediators, such as inducible NO synthase (iNOS), tumor necrosis factor-α (TNF-α), and cyclooxygenases-2 (COX-2), and the modulation of mitogen-activated protein kinases (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. The antioxidant potential of hispolon was attributed to its capacity to neutralize reactive oxygen species (ROS) and to increase the activity of antioxidant enzymes, indicating a possible involvement in the prevention of oxidative stress-related illnesses. Hispolon's antidiabetic activity was associated with the inhibition of aldose reductase and α-glucosidase. Studies on hispolon emphasized its potential use as a promising scaffold for the development of novel therapeutic agents targeting various diseases, including cancer, infectious diseases, inflammatory disorders, and diabetes.

Hispolon inhibits neuronal ferroptosis by promoting the expression of Nrf-2

Research has shown that neuronal ferroptosis is associated with various central nervous system diseases, including Parkinson's disease, acute brain injury, and spinal cord injury. Inhibiting neuronal ferroptosis can greatly alleviate the progression of these diseases. However, there is currently a lack of effective drugs to inhibit neuronal ferroptosis. In this study, we pretreated neuronal cells with Hispolon and subsequently induced a neuronal ferroptosis model using Erastin. We further assessed the changes in the protein expression levels of SLC7A11, GPX4, ACSL4, Nrf-2, and HO-1 using Western blot and immunofluorescence techniques. Additionally, we measured the intracellular levels of Fe2+, GSH, and MDA using relevant assay kits. The research findings revealed that after Hispolon treatment, the expression of the pro-ferroptosis protein ACSL4 decreased, while the expression of the ferroptosis-regulating proteins GPX4 and SLC7A11 increased. Moreover, the use of an Nrf-2-specific inhibitor was able to reverse the effects of Hispolon as mentioned above. In this study, we discovered that Hispolon can promote the expression of Nrf-2 and inhibit the occurrence of neuronal ferroptosis induced by Erastin.

Phytochemicals and bioactive compounds effective against acute myeloid leukemia: A systematic review

This systematic review identified various bioactive compounds which have the potential to serve as novel drugs or leads against acute myeloid leukemia. Acute myeloid leukemia (AML) is a heterogeneous hematopoietic malignancy that arises from the dysregulation of cell differentiation, proliferation, and cell death. The risk factors associated with the onset of AML include long-term exposure to radiation and chemicals such as benzene, smoking, genetic disorders, blood disorders, advancement in age, and others. Although novel strategies to manage AML, including a refinement of the conventional chemotherapy regimens, hypomethylating agents, and molecular targeted drugs, have been developed in recent years, resistance and relapse remain the main clinical problems. In this study, three databases, PubMed/MEDLINE, ScienceDirect, and Google Scholar, were systematically searched to identify various bioactive compounds with antileukemic properties. A total of 518 articles were identified, out of which 59 were viewed as eligible for the current report. From the data extracted, over 60 bioactive compounds were identified and divided into five major groups: flavonoids, alkaloids, organosulfur compounds, terpenes, and terpenoids, and other known and emerging bioactive compounds. The mechanism of actions of the analyzed individual bioactive molecules differs remarkably and includes disrupting chromatin structure, upregulating the synthesis of certain DNA repair proteins, inducing cell cycle arrest and apoptosis, and inhibiting/regulating Hsp90 activities, DNA methyltransferase 1, and histone deacetylase 1.

Augmentation of Docetaxel-Induced Cytotoxicity in Human PC-3 Androgen-Independent Prostate Cancer Cells by Combination With Four Natural Apoptosis-Inducing Anticancer Compounds

Docetaxel (DTX) is the treatment of choice for metastatic castration-resistant prostate cancer. However, developing drug resistance is a significant challenge for achieving effective therapy. This study evaluated the anticancer and synergistic effects on DTX of four natural compounds (calebin A, 3^'-hydroxypterostilbene, hispolon, and tetrahydrocurcumin) using PC-3 androgen-resistant human prostate cancer cells. We utilized the CellTiter-Glo^® luminescent cell viability assay and human PC-3 androgen-independent prostate cancer cells to determine the antiproliferative effects of the four compounds alone and combined with DTX. Cytotoxicity to normal human prostate epithelial cells was tested in parallel using normal immortalized human prostate epithelial cells (RWPE-1). We used cell imaging and quantitative caspase-3 activity to determine whether these compounds induce apoptosis. We also measured the capacity of each drug to inhibit TNF-α-induced NF-kB using a colorimetric assay. Our results showed that all four natural compounds significantly augmented the toxicity of DTX to androgen-resistant PC-3 prostate cancer cells at IC₅₀. Interestingly, when used alone, each of the four compounds had a higher cytotoxic activity to PC-3 than DTX. Mechanistically, these compounds induced apoptosis, which we confirmed by cell imaging and caspase-3 colorimetric assays. Further, when used either alone or combined with DTX, the four test compounds inhibited TNF-α-induced NF-kB production. More significantly, the cytotoxic effects on normal immortalized human prostate epithelial cells were minimal and non-significant, suggesting prostate cancer-specific effects. In conclusion, the combination of DTX with the four test compounds could effectively enhance the anti-prostate cancer activity of DTX. This combination has the added value of reducing the DTX effective concentration. We surmise that calebin A, 3^'-hydroxypterostilbene, hispolon, and tetrahydrocurcumin were all excellent drug candidates that produced significant antiproliferative activity when used alone and synergistically enhanced the anticancer effect of DTX. Further in vivo studies using animal models of prostate cancer are needed to confirm our in vitro findings.

Hispolon induces apoptosis in oral squamous cell carcinoma cells through JNK / HO ‐1 pathway activation

Oral squamous cell carcinoma (OSCC) has a high recurrence rate and poor prognosis. Hispolon, a polyphenolic compound with antiviral, antioxidant, and anticancer activities, is a potential chemotherapy agent. However, few studies have investigated the anti-cancer mechanism of hispolon in oral cancer. This present study used the cell viability assay, clonogenic assay, fluorescent nuclear staining, and flow cytometry assay to analyse the apoptosis-inducing effects of hispolon in OSCC cells. After hispolon treatment, the apoptotic initiators, cleaved caspase-3, -8, and - 9, were upregulated, whereas the cellular inhibitor of apoptosis protein-1 (cIAP1) was downregulated. Furthermore, a proteome profile analysis using a human apoptosis array revealed the overexpression of heme oxygenase-1 (HO-1) by hispolon, which was determined to be involved in caspase-dependent apoptosis. Moreover, cotreatment with hispolon and mitogen-activated protein kinase (MAPK) inhibitors revealed that hispolon induces apoptosis in OSCC cells through activation of the c-Jun N-terminal kinase (JNK) pathway and not the extracellular signal-regulated kinase (ERK) or p38 pathway. These findings indicate that hispolon may exert an anticancer effect on oral cancer cells by upregulating HO-1 and inducing caspase-dependent apoptosis by activating the JNK pathway.

Hispolon alleviates oxidative damage by stimulating the Nrf2 signaling pathway in PC12 cells

Natural products derived from the daily diet are garnering increasing attention for neurodegenerative disease (ND) treatment. Hispolon (His), a small molecule from Phellinus linteus, has been reported to have various pharmacological activities. Here, we evaluated its protective effect on a neuron-like rat pheochromocytoma cell line (PC12). Results showed that His could restore cell death induced by oxidative damage. Nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2) plays a significant role in maintaining cellular redox homeostasis. After treatment with His, some Nrf2-governed antioxidant genes were upregulated in a dose-dependent manner. However, the protective effect of His on PC12 cells was easily terminated by Nrf2 knockdown, demonstrating that Nrf2 is a critical component in this cytoprotective process. Taken together, our study showed that His was not only an effective activator of Nrf2 but also a promising candidate for ND treatment.

Hispolon Induces Apoptosis, Suppresses Migration and Invasion of Glioblastoma Cells and Inhibits GBM Xenograft Tumor Growth In Vivo

Hispolon, a polyphenol compound isolated from Phellinus linteus, has been reported to exhibit antioxidant, antiproliferative, and antitumor activities. This study aimed to explore the antitumor effects of hispolon on glioblastoma multiforme (GBM) cells in vitro and in vivo. The results revealed that hispolon significantly inhibited GBM cell proliferation and induced apoptosis through caspase-9 and caspase-3 activation and PARP cleavage. Hispolon also induced cell cycle G2/M phase arrest in GBM cells, as supported by flow cytometry analysis and confirmed by a decrease in cyclin B1, cdc2, and cdc25c protein expressions in a dose- and time-dependent manner. Furthermore, hispolon suppressed the migration and invasion of GBM cells by modulating epithelial–mesenchymal transition (EMT) markers via wound healing, transwell assays, and real-time PCR. Moreover, hispolon significantly reduced tumor growth in DBTRG xenograft mice and activated caspase-3 in hispolon-treated tumors. Thus, our findings revealed that hispolon is a potential candidate for the treatment of GBM.

Anticancer Perspectives on the Fungal-Derived Polyphenolic Hispolon

BACKGROUND

Cancer is a dreadful disease causing thousands of deaths per year worldwide, which requires precision diagnostics and therapy. Although the selection of therapeutic regimens depends on the cancer type, chemotherapy remains a sustainable treatment strategy despite some of its known side-effects. To date, a number of natural products and their derivatives or analogues have been investigated as potent anticancer drugs. These drug discoveries have aimed for targeted therapy and reduced side-effects, including natural therapeutic regimens.

OBJECTIVE

This review introduces a prospective fungal-derived polyphenol, Hispolon (HIS), as an anticancer agent. Accordingly, this review focuses on exploring the anticancer effect of hispolon based on information extracted from databases such as PubMed, ScienceDirect, MedLine, Web of Science, and Google Scholar.

METHODS

A literature search in PubMed, ScienceDirect, MedLine, Web of Science, and Google Scholar was accomplished, using the keyword 'Hispolon', pairing with 'cancer', 'cytotoxicity', 'cell cycle arrest', 'apoptosis', 'metastasis', 'migration', 'invasion', 'proliferation', 'genotoxicity', 'mutagenicity', 'drug-resistant cancer', 'autophagy', and 'estrogen receptor.

RESULTS

Database-dependent findings from reported research works suggest that HIS can exert anticancer effects by modulating multiple molecular and biochemical pathways, including cell cycle arrest, apoptosis, autophagy, inhibition of proliferation, metastasis, migration, and invasion. Moreover, HIS inhibits the estrogenic activity and exhibits chemoprevention prospects, possibly due to its protective effects such as anticancer and anti-inflammatory mechanisms. To date, a number of HIS derivatives and analogues have been introduced for their anticancer effects in numerous cancer cell lines.

CONCLUSION

Data obtained from this review suggest that hispolon and some of its derivatives can be promising anticancer agents, and may become plant-based cancer chemotherapeutic leads for the development of potent anticancer drugs, alone or in combination with other chemotherapeutic agents.

Hispolon: A natural polyphenol and emerging cancer killer by multiple cellular signaling pathways

Nature as an infinite treasure of chemotypes and pharmacophores will continue to play an imperative role in the drug discovery. Natural products (NPs) such as plant and fungal metabolites have emerged as leads in drug discovery during recent years due to their efficacy, safety and selectivity. The current review summarizes natural sources as well as pharmacological potential of hispolon which is a major constituent of traditional medicinal mushroom Phellinus linteus. The study aims to update the scientific community about recent developments of hispolon in the arena of natural drugs by providing insights into its present status in therapeutic pursuits. Hispolon, a polyphenol has been reported to possess anticancer, antidiabetic, antioxidant, antiviral and anti-inflammatory activities. It fights against cancer via induction of apoptosis, halting cell cycle and inhibition of metastasis by targeting various cellular signaling pathways including PI3K/Akt, MAPK and NF-κB. The current review proposes that hispolon provides a novel opportunity for pharmacological applications and its styrylpyrone carbon skeleton might serve as an attractive scaffold for drug development. However, future researches are recommended to assess bioavailability, toxicological limits, pharmacokinetic and pharmacodynamic profiles of hispolon, in order to establish its potential as a potent multi-targeted drug in the near future.

Attenuation of Lipopolysaccharide-Induced Acute Lung Injury by Hispolon in Mice, Through Regulating the TLR4/PI3K/Akt/mTOR and Keap1/Nrf2/HO-1 Pathways, and Suppressing Oxidative Stress-Mediated ER Stress-Induced Apoptosis and Autophagy

The anti-inflammatory effect of hispolon has identified it as one of the most important compounds from Sanghuangporus sanghuang. The research objectives were to study this compound using an animal model by lipopolysaccharide (LPS)-induced acute lung injury. Hispolon treatment reduced the production of the pro-inflammatory mediator NO, TNF-α, IL-1β, and IL-6 induced by LPS challenge in the lung tissues, as well as decreasing their histological alterations and protein content. Total cell number was also reduced in the bronchoalveolar lavage fluid (BALF). Moreover, hispolon inhibited iNOS, COX-2 and IκB-α and phosphorylated IKK and MAPK, while increasing catalase, SOD, GPx, TLR4, AKT, HO-1, Nrf-2, Keap1 and PPARγ expression, after LPS challenge. It also regulated apoptosis, ER stress and the autophagy signal transduction pathway. The results of this study show that hispolon regulates LPS-induced ER stress (increasing CHOP, PERK, IRE1, ATF6 and GRP78 protein expression), apoptosis (decreasing caspase-3 and Bax and increasing Bcl-2 expression) and autophagy (reducing LC3 I/II and Beclin-1 expression). This in vivo experimental study suggests that hispolon suppresses the LPS-induced activation of inflammatory pathways, oxidative injury, ER stress, apoptosis and autophagy and has the potential to be used therapeutically in major anterior segment lung diseases.

Elucidating the anti-melanoma effect and mechanisms of Hispolon

There is a rapid increase in the incidence of melanoma which has led to a global crisis. Thus, there is a great need for developing novel, safe and effective drugs for the treatment of melanoma. Hispolon is a small molecular weight polyphenol derived from Phellinus linteus, which has antioxidant, anti-inflammatory and anti-proliferative activities. Hispolon has been reported to induce apoptosis in gastric cancer, hepatocellular carcinoma, and myeloid leukemia. However, the anticancer effect in melanoma is not well elucidated. Thus, our present study was to investigate the anti-cancer effect of hispolon on melanoma cancer cells. B16BL6 cells were treated with different concentrations of hispolon for 24 h and the effect on oxidative stress, mitochondrial functions, apoptosis and cell proliferation were studied. Hispolon is a potent generator of reactive oxygen species, nitrite and lipid peroxide levels. Furthermore, it significantly inhibits the expression of Bcl-2 and promotes the expression of Bax, increases the activity of caspase 1 and 3, inhibits mitochondrial Complex I and IV activities. By the above mechanisms, hispolon dose-dependently exhibited the antimelanoma effect similar to the well established pharmacological agent, curcumin. Thus, hispolon can be a potent anti-melanoma drug in the future if the pharmacodynamic effects and the toxicological studies are appropriately carried out.

Involvement of Up-regulation of Death Receptors and Bim in Hispolon-mediated TNF-related Apoptosis-inducing Ligand Sensitization in Human Renal Carcinoma

Background

Hispolon has been shown to possess antitumor effects in various cancer cells. However, the underlying mechanisms are not fully understood. In this study, we evaluated the sensitizing effect of hispolon on TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in human renal carcinoma cells.

Methods

Apoptosis was analyzed by using cell-based cytometer. The mRNA levels were assessed by reverse transcription-PCR. Bax activation was determined by oligomerization and fluorescence-activated cell sorting with Bax-NT monoclonal antibody. The protein expression was measured by Western blotting.

Results

Hispolon induced up-regulation of Bim and death receptors expression at the post-translational level.

Conclusions

Hispolon enhanced TRAIL-mediated apoptosis in renal carcinoma cells, but not in normal cells.

Toxicity and Antigenotoxic Effect of Hispolon Derivatives: Role of Structure in Modulating Cellular Redox State and Thioredoxin Reductase

Hispolon (HS), a bioactive polyphenol, and its derivatives such as hispolon monomethyl ether (HME), hispolon pyrazole (HP), and hispolon monomethyl ether pyrazole (HMEP) were evaluated for comparative toxicity and antigenotoxic effects. The stability of HS derivatives in biological matrices followed the order HS < HP ≈ HME < HMEP. The cytotoxicity analysis of HS derivatives indicated that HP and HMEP were less toxic than HS and HME, respectively, in both normal and tumor cell types. The mechanisms of toxicity of HS and HME involved inhibition of thioredoxin reductase (TrxR) and/or induction of reductive stress. From the enzyme kinetic and docking studies, it was established that HS and HME interacted with the NADPH-binding domain of TrxR through electrostatic and hydrophobic bonds, resulting in inhibition of the catalytic activity. Subsequently, treatment with HS, HP, and HMEP at a nontoxic concentration of 10 μM in Chinese Hamster Ovary (CHO) cells showed significant protection against radiation (4 Gy)-induced DNA damage as assessed by micronuclei and γ-H2AX assays. In conclusion, the above results suggested the importance of phenolic and diketo groups in controlling the stability and toxicity of HS derivatives. The pyrazole derivatives, HP and HMEP, may gain significance in the development of functional foods.

Hispolon Suppresses LPS- or LTA-Induced iNOS/NO Production and Apoptosis in BV-2 Microglial Cells

Hispolon (HIS) is an active polyphenol compound derived from Phellinus linteus (Berkeley & Curtis), and our previous study showed that HIS effectively inhibited inflammatory responses in macrophages [Yang, L.Y., S.C. Shen, K.T. Cheng, G.V. Subbaraju, C.C. Chien and Y.C. Chen. Hispolon inhibition of inflammatory apoptosis through reduction of iNOS/NO production via HO-1 induction in macrophages. J. Ethnopharmacol. 156: 61-72, 2014]; however, its effect on neuronal inflammation is still undefined. In this study, HIS concentration- and time-dependently inhibited lipopolysaccharide (LPS)- and lipoteichoic acid (LTA)-induced inducible nitric oxide (NO) synthase (iNOS)/NO production with increased heme oxygenase (HO)-1 proteins in BV-2 microglial cells. Accordingly, HIS protected BV-2 cells from LPS- or LTA-induced apoptosis, characterized by decreased DNA ladder formation, and caspase-3 and poly(ADP ribose) polymerase (PARP) protein cleavage in BV-2 cells. Similarly, the NOS inhibitor, N-nitro-L-arginine methyl ester (NAME), inhibited LPS- or LTA-induced apoptosis of BV-2 cells, but neither NAME nor HIS showed any inhibition of NO production or cell death induced by the NO donor, sodium nitroprusside (SNP), indicating the involvement of NO in the inflammatory apoptosis of microglial cells. Activation of c-Jun N-terminal kinase (JNK) and nuclear factor (NF)-[Formula: see text]B contributed to LPS- or LTA-induced iNOS/NO production and apoptosis of BV-2 cells, and that was suppressed by HIS. Additionally, HIS possesses activity to induce HO-1 protein expression via activation of extracellular signal-regulated kinase (ERK) in BV-2 cells, and application of the HO inhibitor, tin protoporphyrin (SnPP), or knockdown of HO-1 protein by HO-1 small interfering (si)RNA significantly reversed HIS inhibition of NO production and cell death in BV-2 cells stimulated by LPS. Results of an analysis of the effects of HIS and two structurally related chemicals, i.e. dehydroxy-HIS (D-HIS) and HIS-methyl ester (HIS-ME), showed that HIS expressed the most potent inhibitory effects on iNOS/NO production, JNK activation, and apoptosis in BV-2 microglial cells activated by LPS with increased HO-1 protein expression. Overall these results suggested that HIS possesses inhibitory activity against LPS- or LTA-induced inflammatory responses including iNOS/NO production and apoptosis in BV-2 microglial cells and that the mechanisms involve upregulation of the HO-1 protein and downregulation of JNK/NF-[Formula: see text]B activation. A critical role of hydroxyl at position C3 in the anti-inflammatory actions of HIS against activated BV-2 microglial cells was suggested.

Effects of hispolon on glioblastoma cell growth

Hispolon is a polyphenolic compound isolated from Phellinus linteus which exhibits antitumor activity. Here, we explored the effects of hispolon on human glioblastoma cells U87MG. Cell viability was examined by MTT assay. Growth was investigated by incubating cells with various concentrations of hispolon (25 and 50 µM) for 24, 48 or 72 h and daily cell count. Cell cycle and apoptosis assay were assessed by flow cytometry. Hispolon decreased cell viability in a dose- and time-dependent manner. The cell cycle distribution showed that hispolon enhanced the accumulation of the cells in G2/M phase. Hispolon decreased the expression of G1-S transition-related protein cyclin D4 but increased the expression of CDK inhibitor p21. Additionally, hispolon enhanced the expression of p53. Moreover, hispolon treatment was effective on U87MG cells in inhibiting cell viability and inducing cell apoptosis. Our results indicate that hispolon inhibits the cell viability, induces G2/M cell cycle arrest and apoptosis in glioblastoma U87MG cells, and p53 should play a role in hispolon-mediated antitumor activity.

Tricetin Induces Apoptosis of Human Leukemic HL-60 Cells through a Reactive Oxygen Species-Mediated c-Jun N-Terminal Kinase Activation Pathway

Tricetin is a dietary flavonoid with cytostatic properties and antimetastatic activities in various solid tumors. The anticancer effect of tricetin in nonsolid tumors remains unclear. Herein, the molecular mechanisms by which tricetin exerts its anticancer effects on acute myeloid leukemia (AML) cells were investigated. Results showed that tricetin inhibited cell viability in various types of AML cell lines. Tricetin induced morphological features of apoptosis such as chromatin condensation and phosphatidylserine (PS) externalization, and significantly activated proapoptotic signaling including caspase-8, -9, and -3 activation and poly(ADP-ribose) polymerase (PARP) cleavage in HL-60 AML cells. Of note, tricetin-induced cell growth inhibition was dramatically reversed by a pan caspase and caspase-8- and -9-specific inhibitors, suggesting that this compound mainly acts through a caspase-dependent pathway. Moreover, treatment of HL-60 cells with tricetin induced sustained activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), and inhibition of ERK and JNK by their specific inhibitors respectively promoted and abolished tricetin-induced cell apoptosis. Dichlorofluorescein (DCF) staining showed that intracellular reactive oxygen species (ROS) levels were higher in tricetin-treated HL-60 cells compared to the control group. Moreover, an ROS scavenger, N-acetylcysteine (NAC), reversed tricetin-induced JNK activation and subsequent cell apoptosis. In conclusion, our results indicated that tricetin induced cell death of leukemic HL-60 cells through induction of intracellular oxidative stress following activation of a JNK-mediated apoptosis pathway. A combination of tricetin and an ERK inhibitor may be a better strategy to enhance the anticancer activities of tricetin in AML.

Hispolon suppresses migration and invasion of human nasopharyngeal carcinoma cells by inhibiting the urokinase-plasminogen activator through modulation of the Akt signaling pathway

Hispolon has been reported to possess antioxidant, antiinflammatory, and antitumor activities. However, the effect of hispolon on the metastasis of nasopharyngeal carcinoma (NPC) remains unclear. In this study, we investigated how the antimetastatic activity and relevant signaling pathways of hispolon affected three NPC cell lines. The results revealed that hispolon significantly reduced the migration and invasion of three NPC cells in a dose-dependent manner from 0 to 50 µM. Hispolon also significantly inhibited the activity and expression of urokinase-plasminogen activator (uPA) as well as the phosphorylation of Akt. Moreover, blocking the Akt pathway also enhanced the antimetastatic ability of hispolon in the NPC cells. In conclusion, hispolon inhibited uPA expression and NPC cell metastasis by downregulating Akt signal pathways; therefore, hispolon exerts beneficial effects in chemoprevention. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 645-655, 2017.

CD274 promotes cell cycle entry of leukemia-initiating cells through JNK/Cyclin D2 signaling

Background

CD274 (programmed death ligand 1, also known as B7H1) is expressed in both solid tumors and hematologic malignancies and is of critical importance for the escape of tumor cells from immune surveillance by inhibiting T cell function via its receptor, programmed death 1 (PD-1). Increasing evidence indicates that functional monoclonal antibodies of CD274 may potently enhance the antitumor effect in many cancers. However, the role of CD274 in leukemia-initiating cells (LICs) remains largely unknown.

Methods

We established an MLL-AF9-induced acute myeloid leukemia (AML) model with wild-type (WT) and CD274-null mice to elucidate the role of CD274 in the cell fates of LICs, including self-renewal, differentiation, cell cycle, and apoptosis. RNA sequencing was performed to reveal the potential downstream targets, the results of which were further validated both in vitro and in vivo.

Results

In silico analysis indicated that CD274 level was inversely correlated with the overall survival of AML patients. In Mac-1⁺/c-Kit⁺ mouse LICs, CD274 was expressed at a much higher level than in the normal hematopoietic stem cells (HSCs). The survival of the mice with CD274-null leukemia cells was dramatically extended during the serial transplantation compared with that of their WT counterparts. CD274 deletion led to a significant decrease in LIC frequency and arrest in the G1 phase of the cell cycle. Interestingly, CD274 is not required for the maintenance of HSC pool as shown in our previous study. Mechanistically, we demonstrated that the levels of both phospho-JNK and Cyclin D2 were strikingly downregulated in CD274-null LICs. The overexpression of Cyclin D2 fully rescued the loss of function of CD274. Moreover, CD274 was directly associated with JNK and enhanced the downstream signaling to increase the Cyclin D2 level, promoting leukemia development.

Conclusions

The surface immune molecule CD274 plays a critical role in the proliferation of LICs. The CD274/JNK/Cyclin D2 pathway promotes the cell cycle entry of LICs, which may serve as a novel therapeutic target for the treatment of leukemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0350-6) contains supplementary material, which is available to authorized users.

Combretastatin A-4 Analogue: A Dual-Targeting and Tubulin Inhibitor Containing Antitumor Pt(IV) Moiety with a Unique Mode of Action

Three new Pt(IV) complexes comprising a combretastatin A-4 analogue were designed and synthesized. The resulting antitumor Pt(IV) complexes could significantly improve the antiproliferative activity and overcome the drug resistance of cisplatin in vitro. Interestingly, these novel compounds not only can carry the DNA binding Pt(II) warhead into the cancer cells but also have a small molecule fragment that can inhibit tubulin polymerization. Among them, complex 13, which was attached to an inhibitor of tubulin at one axial position of Pt(IV) octahedral coordination sphere, could effectively enter cancer cells, arrest the cell cycle in HepG-2 cancer cells at G2/M phases, and induce activation of caspases triggering apoptotic signaling via the mitochondrial-dependent apoptosis pathways. Moreover, complex 13 has the ability to effectively inhibit the tumor growth in the HepG-2 xenograft model without causing significant loss of animal body weight in comparison with cisplatin.

Chemical Constituents and Their Bioactivities of Mushroom Phellinus rhabarbarinus

Phellinus rhabarbarinus soaked in wine has folk usages by local residents of Ailao mountain of Yunnan province, China, which were to daub the wound to prevent infection and to drink to enhance immunity and treat other diseases such as cough, gastritis, and cancer. Systemic investigation on the chemical constituents of fruiting bodies of P. rhabarbarinus resulted in the isolation of 11 lanostane triterpenoids (1-10) including three new ones, namely, phellibarins A-C (1-3), together with five ergosterols (11-15). This is the first time reporting secondary metabolites of P. rhabarbarinus. Compounds 2, 3, 7, and 8 showed inhibitory activities against nitric oxide (NO) production in LPS-activated RAW264.7 macrophages, whereas compounds 2-4, 6, 7, and 10 exhibited cytotoxicities against human cancer cell lines. The results of this assessment suggested that the lanostane triterpenoids in fruiting bodies of P. rhabarbarinus played key roles in its folk usages.

Chrysin-organogermanium (IV) complex induced Colo205 cell apoptosis-associated mitochondrial function and anti-angiogenesis

Colorectal cancer, a kind of malignant cancer, has more than 1 million new patients and results in 0.5 million deaths every year globally based on the estimation of Globocan in 2008. One of the most important issues against colon cancer is tumor metastasis. Anti-angiogenesis, a form of targeted therapy uses drugs or other substances to prevent the new blood vessel formation, which is critical for tumor metastasis. In our previous studies, we have demonstrated a simple method to synthesize Chry-Ge complex through the reaction between chrysin and triphenylgermanium bromide. In this work, we investigated the mechanism of Chry-Ge induced Colo205 cell apoptosis. We found that Chry-Ge could induce apoptosis in Colo205 cells in mitochondrial-dependent pathway, cause the reorganization of cytoskeleton and induce the damage of nucleus in Colo205 cells. Besides, Chry-Ge was also found to induce membrane ultrastructural changes in Colo205 cells by AFM. Further, we found that Chry-Ge can inhibit tube formation of human umbilical vascular endothelial cell in vitro. Chry-Ge was also tested in vivo in the chicken chorioallantoic membrane (CAM) assay and found to inhibit bFGF-treated CAMs development. These results suggested that Chry-Ge could induce Colo205 cell apoptosis by mitochondrial pathway and anti-angiogenesis, highlighting the use of organic germanium agents for the treatment of colorectal cancer.

Hispolon inhibits TPA-induced invasion by reducing MMP-9 expression through the NF-κB signaling pathway in MDA-MB-231 human breast cancer cells

Hispolon has been demonstrated to possess analgesic, anti-inflammatory and anticancer activities. However, whether hispolon prevents the invasion of breast carcinoma cells and the underlying mechanisms of its action remain unknown. In the present study, various assays, including a matrigel-based Transwell invasion assay and electrophoretic mobility shift assay, were used to investigate the anti-invasion effect of hispolon and explore its mechanism of action. The results revealed that hispolon inhibited the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced migration and invasion of MDA-MB-231 human breast cancer cells at non-toxic concentrations. Hispolon also prevented the TPA-induced secretion of matrix metalloproteinase-9 (MMP-9) and reduced its expression at the transcriptional and translational levels. Furthermore, the phosphorylation of IκBα was reduced by hispolon, which resulted in the suppression of nuclear factor-κB (NF-κB), and p65 phosphorylation and nuclear translocation. An electrophoretic mobility shift assay demonstrated that NF-κB DNA-binding activity was induced by TPA and inhibited by hispolon. In addition, Bay 11-7082, which is a specific inhibitor of NF-κB, functioned in a similar manner as hispolon and blocked the secretion and expression of MMP-9. In conclusion, the results of the present study indicated that hispolon inhibited TPA-induced migration and invasion of MDA-MB-231 cells by reducing the secretion and expression of MMP-9 through the NF-κB signaling pathway.

BCR/ABL mRNA targeting small interfering RNA effects on proliferation and apoptosis in chronic myeloid leukemia

BACKGROUND

To investigate the effects of small interference RNA (siRNA) targeting BCR/ABL mRNA on proliferation and apoptosis in the K562 human chronic myeloid leukemia (CML) cell line and to provide a theoretical rationale and experimental evidence for its potential clinical application for anti-CML treatment.

MATERIALS AND METHODS

The gene sequence for BCR/ABL mRNA was found from the GeneBank. The target gene site on the BCR/ABL mRNA were selected according to Max-Planck-Institute (MPI) and rational siRNA design rules, the secondary structure of the candidate targeted mRNA was predicted, the relevant thermodynamic parameters were analyzed, and the targeted gene sequences were compared with BLAST to eliminate any sequences with significant homology. Inhibition of proliferation was evaluated by MTT assay and colony-formation inhibiting test. Apoptosis was determined by flow cytometry (FCM) and the morphology of apoptotic cells was identified by Giemsa-Wright staining. Western blotting was used to analyze the expression of BCR/ABL fusion protein in K562 cells after siRNA treatment.

RESULTS

The mRNA local secondary structure calculated by RNA structure software, and the optimal design of specific siRNA were contributed by bioinformatics rules. Five sequences of BCR/ABL siRNAs were designed and synthesized in vitro. Three sequences, siRNA1384, siRNA1276 and siRNA1786, which showed the most effective inhibition of K562 cell growth, were identified among the five candidate siRNAs, with a cell proliferative inhibitory rate nearly 50% after exposure to 12.5 nmol/L~50 nmol/L siRNA1384 for 24,48 and 72 hours. The 50% inhibitory concentrations (IC50) of siRNA1384, siRNA1276 and siRNA1786 for 24 hours were 46.6 nmol/L, 59.3 nmol/L and 62.6 nmol/L, respectively, and 65.668 nmol/L, 76.6 nmol/L, 74.4 nmol/L for 72 hours. The colony-formation inhibiting test also indicated that, compared with control, cell growth of siRNA treated group was inhibited. FCM results showed that the rate of cell apoptosis increased 24 hours after transfecting siRNA. The results of annexinV/PI staining indicated that the rate of apoptosis imcreased (1.53%, 15.3%, 64.5%, 57.5% and 21.5%) following treamtne with siRNAs (siRNA34, siRNA372, siRNA1384, siRNA1276 and siRNA1786). Morphological analysis showed td typical morphologic changes of apoptosis such as shrunken, fragmentation nucleus as well as "apoptotic bodies" after K562 cell exposure to siRNA. Western blot analysis showed that BCR/ABL protein was reduced sharply after a single dose of 50 nmol/L siRNA transfection.

CONCLUSIONS

Proliferation of K562 cells was remarkbly inhibited by siRNAs (siRNA1384, siRNA1276 and siRNA1786) in a concentration-dependent manner in vitro, with effective induction of apoptosis at a concentration of 50 nmol/L. One anti-leukemia mechanism in K562 cells appeared that BCR/ABL targeted protein was highly down-regulated. The siRNAs (siRNA1384, siRNA1276 and siRNA1786) may prove valuable in the treatment of CML.

Timosaponin AIII mediates caspase activation and induces apoptosis through JNK1/2 pathway in human promyelocytic leukemia cells

Timosaponin AIII (TAIII) is a steroidal saponin isolated from Anemarrhena asphodeloides that has been shown to inhibit cell growth and induce apoptosis in cancer. However, the effect of TAIII on acute myeloid leukemia (AML) remains unclear. Here, the molecular mechanism by which TAIII-induced apoptosis affects human AML cells was investigated. The results showed that TAIII significantly inhibited cell proliferation of four AML cell lines (MV4-11, U937, THP-1, and HL-60). Furthermore, TAIII induced apoptosis of HL-60 cells through caspase-3, caspase-8, and caspase-9 activations and PARP cleavage in a dose- and time-dependent manner. Moreover, Western blot analysis also showed that TAIII increased phosphorylation of JNK1/2 and p38 MAPK in a dose-dependent manner. Inhibition of JNK1/2 by specific inhibitors significantly abolished the TAIII-induced activation of the caspase-8. Taken together, our results suggest that TAIII induces HL-60 cell apoptosis through JNK1/2 pathways and could serve as a potential additional chemotherapeutic agent for treating AML.

Hispolon inhibition of inflammatory apoptosis through reduction of iNOS/NO production via HO-1 induction in macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Phellinus linteus (Berkeley & Curtis), a well-known medical fungus, has long been used as a traditional medicine in Oriental countries to treat various diseases, and hispolon (HIS) is one of its bioactive components. HIS is known to possess potent antineoplastic and antiviral properties; however, its effect on inflammatory apoptosis is still undefined.

MATERIALS AND METHODS

RAW264.7 macrophages were incubated with HIS for 30 min followed by LPS, LTA, or PGN stimulation for 12h. The expression of indicated proteins AP-1 and NF-κB transcriptional activities was examined by Western blotting using specific antibodies. Levels of NO and ROS were examined by Griess reaction, and DCHF-DA staining via flow cytometric analysis, respectively. AP-1 and NF-κB transcriptional activities were detected by luciferase reporter assay. Knockdown of HO-1 protein expression was performed by transfection of macrophages with HO-1 siRNA. Pharmacological inhibitors including ROS scavenger NAC, JNK inhibitor SP600125, NF-κB inhibitor BAY117082 were applied for mechanism study.

RESULTS

HIS showed concentration-dependent inhibition of LPS, LTA, and PGN-induced iNOS protein expressions and NO production by RAW264.7 macrophages. Accordingly, HIS protected RAW264.7 cells from LPS-, LTA-, and PGN-induced apoptosis. Increased HO-1 by HIS was detected at both protein and mRNA levels along with an increase in intracellular peroxide, and this was inhibited by the translational inhibitor, cycloheximide (CHX), the transcriptional inhibitor, actinomycin D (Act D), and the reactive oxygen species scavenger, N-acetylcysteine (NAC). A mechanistic study indicated that inhibition of c-Jun N-terminal kinase (JNK) protein phosphorylation, and activator protein (AP)-1 and nuclear factor (NF)-κB activation were involved in the anti-inflammatory actions of HIS in macrophages. A structure-activity relationship analysis showed that HIS expressed the most potent effect of inhibiting iNOS and apoptosis elicited by LPS, LTA, and PGN with a significant increase in HO-1 protein in macrophages.

CONCLUSIONS

Evidence supporting HIS prevention of inflammatory apoptosis via blocking NO production and inducing HO-1 protein expression in macrophages is provided, and the hydroxyl at position C3 is a critical substitution for the anti-inflammatory actions of HIS.

The anticancer effects of hispolon on lung cancer cells

Hispolon is isolated from Phellinus igniarius and exhibits antitumor activity. Here, we explored the effects of hispolon on the lung cancer A549 and H661 cells. Cells were incubated with various concentrations of hispolon (0, 5, 10, 20, 40, 80 or 160μM) for 12, 24, 48 or 72h. Cell viability was examined by MTT assay. Cell cycle and apoptosis assay were assessed by flow cytometry. Hispolon decreased cell viability in a dose- and time-dependent manner. The cell cycle distribution showed that hispolon enhanced the accumulations of the cells in G0/G1 phase. Mechanically, hispolon decreased the expression of G1-S transition-related proteins: Cyclin D1, cyclin E, CDK2, CDK4 and CDK6, but increased the expression of CDK inhibitor p21(CIP1) and p27(KIP1). Moreover, hispolon induced cell apoptosis through activation of the mitochondrial pathway, evidenced by the loss of mitochondrial membrane potential, the release of cytochrome c into cytosol, and the cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP) in hispolon-treated cells. Additionally, hispolon enhanced the expression of p53, specific silencing of which almost completely reversed hispolon-mediated antitumor activity. Moreover, hispolon treatment was more effective on H661 cells than on A549 cells in inhibiting cell viability and inducing cell apoptosis. Our results indicate that hispolon inhibits the cell viability, induces G0/G1 cell cycle arrest and apoptosis in lung cancer cells and p53 plays a critical role in hispolon-mediated antitumor activity.

Mig-2 attenuates cisplatin-induced apoptosis of human glioma cells in vitro through AKT/JNK and AKT/p38 signaling pathways

AIM

Mig-2 (also known as Kindlin-2 and FERMT2) is an important regulator of integrin activation and cell-extracellular matrix adhesion, and involved in carcinogenesis and tumor progression. The aim of this study was to investigate the role of mig-2 in cisplatin-induced apoptosis of human glioma cells in vitro.

METHODS

The expression of mig-2 was modulated in human glioma H4, HS 683 and U-87 MG cells by transfection with a plasmid carrying mig-2 or mig-2 siRNA. Cisplatin-induced apoptosis was detected using Annexin V/PI staining and flow cytometry, as well as MTS analyses. The expression of apoptosis-related or signaling proteins was examined using Western blotting analysis. H4 cells were transfected with plasmids carrying mig-2 mutants to determine the functional domain of mig-2.

RESULTS

In the 3 glioma cell lines tested, overexpression of mig-2 significantly attenuated cisplatin-induced apoptosis, whereas knock-down of mig-2 potentiated the apoptosis. The mechanisms of action of mig-2 were further addressed in H4 cells: overexpression of mig-2 markedly reduced cleaved caspase-9, caspase-8, caspase-3 and PARP, as well as p-JNK and p-p38, and increased p-AKT in cisplatin-treated H4 cells, whereas mig-2 siRNA reversely changed these apoptosis-related and signaling proteins. Furthermore, pretreatment with JNK inhibitor SP600125 and p38 inhibitor SB203580, or with AKT inhibitor LY294002 abolished the effects of mig-2 on cisplaxtin-induced apoptosis. In H4 cells, GFP-mig-2 F3 plasmid that contained only the F3 subdomain showed the same efficiency in attenuating cisplatin-induced apoptosis, as the mig-2 wild-type vector did, whereas GFP-mig-2 (1-541) plasmid that lacked the F3 subdomain was inactive.

CONCLUSION

Mig-2 significantly attenuates the antitumor action of cisplatin against human glioma cells in vitro through AKT/JNK and AKT/p38 signaling pathways. The F3 subdomain of mig-2 is necessary and sufficient for this effect.

Nobiletin suppresses the proliferation and induces apoptosis involving MAPKs and caspase-8/-9/-3 signals in human acute myeloid leukemia cells

Nobiletin, a compound isolated from citrus fruits, is a polymethoxylated flavone derivative that was shown to have anti-inflammatory and anticancer activities in various solid tumors. The anticancer effect of nobiletin on nonsolid tumor remains unclear. Herein, the molecular mechanisms by which nobiletin exerts its anticancer effects on acute myeloid leukemia (AML) cells were investigated. The results showed that nobiletin suppressed cell proliferation in various types of AML cell lines. Moreover, nobiletin induced cell-cycle arrest of HL-60 AML cells at the G0/G1 phase by suppressing extracellular signal-regulated kinase (ERK) activity. Furthermore, nobiletin effectively induced apoptosis of HL-60 cells through caspase-8, caspase-9, and caspases-3 activation concomitantly with a marked induction of p38 mitogen-activated protein kinase (MAPK) activation, but without affecting expression levels of Bcl-2, Bax, or Bid. Taken together, our results suggest that nobiletin inhibited HL-60 cell proliferation through inducing cell-cycle arrest and apoptosis and could serve as a potential additional chemotherapeutic agent for treating AML.

Nobiletin suppresses the proliferation and induces apoptosis involving MAPKs and caspase-8/-9/-3 signals in human acute myeloid leukemia cells

Nobiletin, a compound isolated from citrus fruits, is a polymethoxylated flavone derivative that was shown to have anti-inflammatory and anticancer activities in various solid tumors. The anticancer effect of nobiletin on nonsolid tumor remains unclear. Herein, the molecular mechanisms by which nobiletin exerts its anticancer effects on acute myeloid leukemia (AML) cells were investigated. The results showed that nobiletin suppressed cell proliferation in various types of AML cell lines. Moreover, nobiletin induced cell-cycle arrest of HL-60 AML cells at the G0/G1 phase by suppressing extracellular signal-regulated kinase (ERK) activity. Furthermore, nobiletin effectively induced apoptosis of HL-60 cells through caspase-8, caspase-9, and caspases-3 activation concomitantly with a marked induction of p38 mitogen-activated protein kinase (MAPK) activation, but without affecting expression levels of Bcl-2, Bax, or Bid. Taken together, our results suggest that nobiletin inhibited HL-60 cell proliferation through inducing cell-cycle arrest and apoptosis and could serve as a potential additional chemotherapeutic agent for treating AML.

Hispolon decreases melanin production and induces apoptosis in melanoma cells through the downregulation of tyrosinase and microphthalmia-associated transcription factor (MITF) expressions and the activation of caspase-3, -8 and -9

Hispolon is one of the most important functional compounds that forms Phellinus linteus (Berkeley & Curtis) Teng. Hispolon has antioxidant, anti-inflammatory, antiproliferative and anticancer effects. In this study, we analyzed the functions of hispolon on melanogenesis and apoptosis in B16-F10 melanoma cells. The results demonstrated that hispolon is not an enzymatic inhibitor for tyrosinase; rather, it represses the expression of tyrosinase and the microphthalmia-associated transcription factor (MITF) to reduce the production of melanin in α-melanocyte-stimulating hormone (α-MSH)-stimulated B16-F10 cells at lower concentrations (less than 2 μM). In contrast, at higher concentration (greater than 10 μM), hispolon can induce activity of caspase-3, -8 and -9 to trigger apoptosis of B16-F10 cells but not of Detroit 551 normal fibroblast cells. Therefore, we suggest that hispolon has the potential to treat hyperpigmentation diseases and melanoma skin cancer in the future.