Key cell signaling pathways modulated by zerumbone: Role in the prevention and treatment of cancer

Autophagy-modulating phytochemicals in cancer therapeutics: Current evidences and future perspectives

Autophagy is an intracellular catabolic self-cannibalism that eliminates dysfunctional cytoplasmic cargos by the fusion of cargo-containing autophagosomes with lysosomes to maintain cyto-homeostasis. Autophagy sustains a dynamic interlink between cytoprotective and cytostatic function during malignant transformation in a context-dependent manner. The antioxidant and immunomodulatory phyto-products govern autophagy and autophagy-associated signaling pathways to combat cellular incompetence during malignant transformation. Moreover, in a close cellular signaling circuit, autophagy regulates aberrant epigenetic modulation and inflammation, which limits tumor metastasis. Thus, manipulating autophagy for induction of cell death and associated regulatory phenomena will embark on a new strategy for tumor suppression with wide therapeutic implications. Despite the prodigious availability of lead pharmacophores in nature, the central autophagy regulating entities, their explicit target, as well as pre-clinical and clinical assessment remains a major question to be answered. In addition to this, the stage-specific regulation of autophagy and mode of action with natural products in regulating the key autophagic molecules, control of tumor-specific pathways in relation to modulation of autophagic network specify therapeutic target in caner. Moreover, the molecular pathway specificity and enhanced efficacy of the pre-existing chemotherapeutic agents in co-treatment with these phytochemicals hold high prevalence for target specific cancer therapeutics. Hence, the multi-specific role of phytochemicals in a cellular and tumor context dependent manner raises immense curiosity for investigating of novel therapeutic avenues. In this perspective, this review discusses about diverse implicit mechanisms deployed by the bioactive compounds in diagnosis and therapeutics approach during cancer progression with special insight into autophagic regulation.

Vitexin abrogates invasion and survival of hepatocellular carcinoma cells through targeting STAT3 signaling pathway

Hepatocellular carcinoma (HCC) is a major malignancy that stands second in terms of global cancer-related mortality. STAT3 has been described as a latent transcription factor that promotes tumorigenesis. This study was designed to examine the effect of vitexin on STAT3 signaling and important hallmarks of cancer. HCC cells were employed to decipher the impact of vitexin on activation of STAT3 signaling using Western blotting, EMSA, immunocytochemistry, and reporter assay. The combinational apoptotic effects of vitexin with approved anti-cancer drugs was examined by live-dead assay, and its anti-invasive potential was studied using matrigel assay. The results obtained in cell-based assays were verified using in silico analysis. Vitexin effectively inhibited sustained activation of JAK1, JAK2, Src, and STAT3 in HCC cells. Vitexin downregulated DNA binding ability, reduced the nuclear pool of STAT3, and diminished epidermal growth factor (EGF)-driven STAT3 gene expression. Interestingly, treatment with tyrosine phosphatase inhibitor altered the vitexin-induced STAT3 phosphorylation, and the attenuation of STAT3 by vitexin was found to be driven through the upregulation of PTPεC. The combinational studies indicated that vitexin can exhibit substantial apoptotic effects with doxorubicin and sorafenib. It also suppressed the CXCL12-induced cell invasion. The results of cell-based assays are supported by in silico analysis as the vitexin displayed favorable interaction with kinase domain of JAK2 protein. Overall, this study demonstrated that vitexin can act as a potential blocker of the STAT3 signaling cascade and mitigate the survival as well as invasion of HCC cells.

Assessment of the Antitumor Potential of Umbelliprenin, a Naturally Occurring Sesquiterpene Coumarin

Cancer is one of the greatest causes of mortality worldwide. The prevalence rates of different types of cancer is increasing around the world as well. Limitations in chemotherapy and radiotherapy, owing to multiple side effects including cytotoxic effects of antitumor compounds on normal cells as well as the development of resistance to these treatment options in patients, create a serious threat to successful treatment of cancer. The use of natural compounds to prevent and treat cancers has been found to be quite effective, with fewer adverse effects found in patients. Umbelliprenin (UMB) is a naturally occurring sesquiterpene compound found in Ferula species and recently in Artemisia absinthium. Many studies have highlighted the antitumor potential of UMB in different cancer cell lines as well as in animal models. UMB exerts its anticancer actions by regulating extrinsic and intrinsic apoptotic pathways; causing inhibition of the cell cycle at the G0/G1 phase; and attenuating migration and invasion by modulating the Wnt signaling, NF-ĸB, TGFβ, and Fox3 signaling pathways. UMB also affects the key hallmarks of tumor cells by attenuating tumor growth, angiogenesis, and metastasis. This review provides an insight into the role of UMB as a potential antitumor drug for different malignancies and highlights the signaling cascades affected by UMB treatment in diverse tumor cell lines and preclinical models.

Therapeutic Emergence of Rhein as a Potential Anticancer Drug: A Review of Its Molecular Targets and Anticancer Properties

According to the World Health Organization (WHO), cancer is the second-highest cause of mortality in the world, and it kills nearly 9.6 million people annually. Besides the fatality of the disease, poor prognosis, cost of conventional therapies, and associated side-effects add more burden to patients, post-diagnosis. Therefore, the search for alternatives for the treatment of cancer that are safe, multi-targeted, effective, and cost-effective has compelled us to go back to ancient systems of medicine. Natural herbs and plant formulations are laden with a variety of phytochemicals. One such compound is rhein, which is an anthraquinone derived from the roots of Rheum spp. and Polygonum multiflorum. In ethnomedicine, these plants are used for the treatment of inflammation, osteoarthritis, diabetes, and bacterial and helminthic infections. Increasing evidence suggests that this compound can suppress breast cancer, cervical cancer, colon cancer, lung cancer, ovarian cancer, etc. in both in vitro and in vivo settings. Recent studies have reported that this compound modulates different signaling cascades in cancer cells and can prevent angiogenesis and progression of different types of cancers. The present review highlights the cancer-preventing and therapeutic properties of rhein based on the available literature, which will help to extend further research to establish the chemoprotective and therapeutic roles of rhein compared to other conventional drugs. Future pharmacokinetic and toxicological studies could support this compound as an effective anticancer agent.

Zerumbone Promotes Cytotoxicity in Human Malignant Glioblastoma Cells through Reactive Oxygen Species (ROS) Generation

Glioblastoma multiforme (GBM) is the most hostile tumor in the central nervous system. Unfortunately, the prognosis of GBM patients is poor following surgical interventions, chemotherapy, and radiotherapy. Consequently, more efficient and effective treatment options for the treatment of GBM need to be explored. Zerumbone, as a sesquiterpene derived from Zingiber zerumbet Smith, has substantial cytotoxic and antiproliferative activities in some types of cancer. Here, we show that exposure of GBM cells (U-87 MG) to Zerumbone demonstrated significant growth inhibition in a concentration-dependent manner. Zerumbone also induced apoptosis and caused cell cycle arrest of human GBM U-87 MG cells in the G2/M phase of the cell cycle. In detail, the apoptotic process triggered by Zerumbone involved the upregulation of proapoptotic Bax and the suppression of antiapoptotic Bcl-2 genes expression as determined by qRT-PCR. Moreover, Zerumbone enhanced the generation of reactive oxygen species (ROS), and N-acetyl cysteine (NAC), as an antioxidant, reversed the ROS-induced cytotoxicity of U-87 MG cells. The Western blot analysis suggested that Zerumbone activated the NF-κB p65, which was partly inhibited by NAC treatment. Collectively, our results confirmed that Zerumbone induces cytotoxicity by ROS generation. Thus, the study raises the possibility of Zerumbone as a potential natural agent for treating GBM due to its ability to induce cytotoxicity.

Targeting AKT/mTOR in Oral Cancer: Mechanisms and Advances in Clinical Trials

Oral cancer (OC) is a devastating disease that takes the lives of lots of people globally every year. The current spectrum of treatment modalities does not meet the needs of the patients. The disease heterogeneity demands personalized medicine or targeted therapies. Therefore, there is an urgent need to identify potential targets for the treatment of OC. Abundant evidence has suggested that the components of the protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway are intrinsic factors for carcinogenesis. The AKT protein is central to the proliferation and survival of normal and cancer cells, and its downstream protein, mTOR, also plays an indispensable role in the cellular processes. The wide involvement of the AKT/mTOR pathway has been noted in oral squamous cell carcinoma (OSCC). This axis significantly regulates the various hallmarks of cancer, like proliferation, survival, angiogenesis, invasion, metastasis, autophagy, and epithelial-to-mesenchymal transition (EMT). Activated AKT/mTOR signaling is also associated with circadian signaling, chemoresistance and radio-resistance in OC cells. Several miRNAs, circRNAs and lncRNAs also modulate this pathway. The association of this axis with the process of tumorigenesis has culminated in the identification of its specific inhibitors for the prevention and treatment of OC. In this review, we discussed the significance of AKT/mTOR signaling in OC and its potential as a therapeutic target for the management of OC. This article also provided an update on several AKT/mTOR inhibitors that emerged as promising candidates for therapeutic interventions against OC/head and neck cancer (HNC) in clinical studies.

Nobiletin in Cancer Therapy: How This Plant Derived-Natural Compound Targets Various Oncogene and Onco-Suppressor Pathways

Cancer therapy is a growing field, and annually, a high number of research is performed to develop novel antitumor drugs. Attempts to find new antitumor drugs continue, since cancer cells are able to acquire resistance to conventional drugs. Natural chemicals can be considered as promising candidates in the field of cancer therapy due to their multiple-targeting capability. The nobiletin (NOB) is a ubiquitous flavone isolated from Citrus fruits. The NOB has a variety of pharmacological activities, such as antidiabetes, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective. Among them, the antitumor activity of NOB has been under attention over recent years. In this review, we comprehensively describe the efficacy of NOB in cancer therapy. NOB induces apoptosis and cell cycle arrest in cancer cells. It can suppress migration and invasion of cancer cells via the inhibition of epithelial-to-mesenchymal transition (EMT) and EMT-related factors such as TGF-β, ZEB, Slug, and Snail. Besides, NOB inhibits oncogene factors such as STAT3, NF-κB, Akt, PI3K, Wnt, and so on. Noteworthy, onco-suppressor factors such as microRNA-7 and -200b undergo upregulation by NOB in cancer therapy. These onco-suppressor and oncogene pathways and mechanisms are discussed in this review.

Garcinol Exhibits Anti-Neoplastic Effects by Targeting Diverse Oncogenic Factors in Tumor Cells

Garcinol, a polyisoprenylated benzophenone, is the medicinal component obtained from fruits and leaves of Garcinia indica (G. indica) and has traditionally been extensively used for its antioxidant and anti-inflammatory properties. In addition, it has been also been experimentally illustrated to elicit anti-cancer properties. Several in vitro and in vivo studies have illustrated the potential therapeutic efficiency of garcinol in management of different malignancies. It mainly acts as an inhibitor of cellular processes via regulation of transcription factors NF-κB and JAK/STAT3 in tumor cells and have been demonstrated to effectively inhibit growth of malignant cell population. Numerous studies have highlighted the anti-neoplastic potential of garcinol in different oncological transformations including colon cancer, breast cancer, prostate cancer, head and neck cancer, hepatocellular carcinoma, etc. However, use of garcinol is still in its pre-clinical stage and this is mainly attributed to the limitations of conclusive evaluation of pharmacological parameters. This necessitates evaluation of garcinol pharmacokinetics to precisely identify an appropriate dose and route of administration, tolerability, and potency under physiological conditions along with characterization of a therapeutic index. Hence, the research is presently ongoing in the dimension of exploring the precise metabolic mechanism of garcinol. Despite various lacunae, garcinol has presented with promising anti-cancer effects. Hence, this review is motivated by the constantly emerging and promising positive anti-cancerous effects of garcinol. This review is the first effort to summarize the mechanism of action of garcinol in modulation of anti-cancer effect via regulation of different cellular processes.

Evodiamine Mitigates Cellular Growth and Promotes Apoptosis by Targeting the c-Met Pathway in Prostate Cancer Cells

Evodiamine (EVO) is an indoloquinazoline alkaloid that exerts its various anti-oncogenic actions by blocking phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt), mitogen-activated protein kinase (MAPK), c-Met, and nuclear factor kappa B (NF-κB) signaling pathways, thus leading to apoptosis of tumor cells. We investigated the ability of EVO to affect hepatocyte growth factor (HGF)-induced c-Met/Src/STAT3 activation cascades in castration-resistant prostate cancer (CRPC). First, we noted that EVO showed cytotoxicity and anti-proliferation activities in PC-3 and DU145 cells. Next, we found that EVO markedly inhibited HGF-induced c-Met/Src/STAT3 phosphorylation and impaired the nuclear translocation of STAT3 protein. Then, we noted that EVO arrested the cell cycle, caused apoptosis, and downregulated the expression of various carcinogenic markers such as B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), cyclin D1, cyclooxygenase 2 (COX-2), survivin, vascular endothelial growth factor (VEGF), and matrix metallopeptidases 9 (MMP-9). Moreover, it was observed that in cPC-3 and DU145 cells transfected with c-Met small interfering RNA (siRNA), Src/STAT3 activation was also mitigated and led to a decrease in EVO-induced apoptotic cell death. According to our results, EVO can abrogate the activation of the c-Met/Src/STAT3 signaling axis and thus plays a role as a robust suppressor of tumor cell survival, proliferation, and angiogenesis.

An Overview of the Potential Antineoplastic Effects of Casticin

Cancer persists as one of the leading causes of deaths worldwide, contributing to approximately 9.6 million deaths per annum in recent years. Despite the numerous advancements in cancer treatment, there is still abundant scope to mitigate recurrence, adverse side effects and toxicities caused by existing pharmaceutical drugs. To achieve this, many phytochemicals from plants and natural products have been tested against cancer cell lines in vivo and in vitro. Likewise, casticin, a flavonoid extracted from the Vitex species, has been isolated from the leaves and seeds of V. trifolia and V. agnus-castus. Casticin possesses a wide range of therapeutic properties, including analgesic, anti-inflammatory, antiangiogenic, antiasthmatic and antineoplastic activities. Several studies have been conducted on the anticancer effects of casticin against cancers, including breast, bladder, oral, lung, leukemia and hepatocellular carcinomas. The compound inhibits invasion, migration and proliferation and induces apoptosis (casticin-induced, ROS-mediated and mitochondrial-dependent) and cell cycle arrest (G0/G1, G2/M, etc.) through different signaling pathways, namely the PI3K/Akt, NF-κB, STAT3 and FOXO3a/FoxM1 pathways. This review summarizes the chemo-preventive ability of casticin as an antineoplastic agent against several malignancies.

Dietary zerumbone from shampoo ginger: new insights into its antioxidant and anticancer activity

The dietary sesquiterpene dienone zerumbone (ZER) selectively targets cancer cells, inducing mitochondrial dysfunction and apoptosis, and protects non-cancerous cells towards oxidative stress and insult. This study examines the in vitro effects of ZER on lipid peroxidation in biological systems (cholesterol and phospholipid membrane oxidation) and explores its antitumor action in terms of its ability to modulate cancer cell lipid profile. Evaluation of the antioxidant activity of ZER showed that this compound is unable to trap lipoperoxyl radicals per se. ZER significantly modulated the total lipid and fatty acid profiles in cancer cells, inducing marked changes in the phospholipid/cholesterol ratio, with significant decreases in the levels of oleic and palmitic acids and a marked increase of stearic acid. Cell-based fluorescent measurements of intracellular membranes and lipid droplets using the Nile Red staining technique showed that in cancer cells, ZER induced significant accumulation of cytosolic lipid droplets and altered cell membrane organization/protein dynamics, depolarizing the mitochondrial membranes and inducing apoptosis and alteration of nuclear morphology. The modulatory activity of ZER on the total lipid and fatty acid profiles and lipid droplets may therefore represent another possible mechanism of its anticancer properties.

Zerumbone Protects against Carbon Tetrachloride (CCl4)-Induced Acute Liver Injury in Mice via Inhibiting Oxidative Stress and the Inflammatory Response: Involving the TLR4/NF-κB/COX-2 Pathway

The natural compound Zerumbone (hereinafter referred to as ZER), a monocyclic sesquiterpenoid, has been reported to possess many pharmacological properties, including antioxidant and anti-inflammatory properties. This study aimed to investigate the underlying mechanism of ZER against acute liver injury (ALI) in CCl₄-induced mice models. ICR mice were pretreated intraperitoneally with ZER for five days, then received a CCl₄ injection two hours after the last ZER administration and were sacrificed 24 h later. Examination of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and the histopathological analysis confirmed the hepatoprotective effect of ZER. Biochemical assays revealed that ZER pretreatment recovered the activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), restored the glutathione (GSH) reservoir, and reduced the production of malondialdehyde (MDA), all in a dose-dependent manner. Furthermore, administration of ZER in vivo reduced the release amounts of pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) and inhibited the increased protein levels of Toll-like receptor 4 (TLR4), nuclear factor-kappaB (NF-κB) p-p65, and cyclooxygenase (COX-2). Further studies in lipopolysaccharide (LPS)-induced Raw264.7 inflammatory cellular models verified that ZER could inhibit inflammation via inactivating the TLR4/NF-κB/COX-2 pathway. Thus, our study indicated that ZER exhibited a hepatoprotective effect against ALI through its antioxidant and anti-inflammatory activities and the possible mechanism might be mediated by the TLR4/NF-κB/COX-2 pathway. Collectively, our studies indicate ZER could be a potential candidate for chemical liver injury treatment.

Dietary zerumbone, a sesquiterpene, ameliorates hepatotoxin-mediated acute and chronic liver injury in mice

Acute liver injury (ALI) is a life-threatening clinical syndrome. Long-lasting liver injury can lead to chronic hepatic inflammation and fibrogenic responses. Zerumbone (ZER), the main constituent of rhizomes of Zingiber zerumbet Smith, has a variety of functions including anticancer activity. We investigated the role of ZER on the progression of hepatotoxin-induced liver injury. Single or repeated injection of CCl₄ was used to induce acute or chronic liver injury, respectively. Mice were orally administered with ZER (10, 50 mg/kg) during the experimental period. Histopathologic analysis and serum biochemical levels revealed that ZER had hepatoprotective activities against ALI. Similar effects of ZER on injured livers were confirmed by analyses of inflammation and apoptosis-related genes. Western blot analysis showed that protein levels of apoptotic molecules were decreased, whereas antiapoptotic protein levels were conversely increased in injured livers treated with ZER. Furthermore, chronic liver injury and its associated fibrogenesis in mice were reduced by ZER treatment. These findings from our in vivo experiments further indicate that ZER could alleviate hepatocellular toxicity and inhibit activation of primary hepatic stellate cells. Our results suggest that ZER might have potential as a safe and prophylactic alternative to prevent acute and chronic liver injury.

Potential of Zerumbone as an Anti-Cancer Agent

Cancer is still a major risk factor to public health globally, causing approximately 9.8 million deaths worldwide in 2018. Despite advances in conventional treatment modalities for cancer treatment, there are still few effective therapies available due to the lack of selectivity, adverse side effects, non-specific toxicities, and tumour recurrence. Therefore, there is an immediate need for essential alternative therapeutics, which can prove to be beneficial and safe against cancer. Various phytochemicals from natural sources have been found to exhibit beneficial medicinal properties against various human diseases. Zerumbone is one such compound isolated from Zingiber zerumbet Smith that possesses diverse pharmacological properties including those of antioxidant, antibacterial, antipyretic, anti-inflammatory, immunomodulatory, as well as anti-neoplastic. Zerumbone has shown its anti-cancer effects by causing significant suppression of proliferation, survival, angiogenesis, invasion, and metastasis through the molecular modulation of different pathways such as NF-κB, Akt, and IL-6/JAK2/STAT3 (interleukin-6/janus kinase-2/signal transducer and activator of transcription 3) and their downstream target proteins. The current review briefly summarizes the modes of action and therapeutic potential of zerumbone against various cancers.

Zerumbone Suppresses Human Colorectal Cancer Invasion and Metastasis via Modulation of FAk/PI3k/NFκB-uPA Pathway

The current study explored the basic molecular mechanisms of zerumbone (ZER), an herbal compound, in inhibiting the migration and invasion of colorectal cancer (CRC) cells in vitro. Two types of CRC cells, namely HCT-116 and SW48, were treated with various concentrations of ZER (8, 16, and 24 µM) for 24, 48, and 72 h, respectively. In vitro assays were performed to determine alterations in proliferation ability, mRNA expression and protein levels, and migration and invasion potential of CRC cells. An SYBR Green-based quantitative polymerase chain reaction (PCR) was utilized to detect the gene expression of focal adhesion kinase (FAK), nuclear factor (NF)-κB, and urokinase-type plasminogen activator (uPA) followed by the evaluation of the level of proteins by western blotting. Migration and invasion potentials of HCT-116 and SW48 cells treated by ZER were examined using migration and invasion assay kits, respectively. We compared the results of all experiments with control groups, including FAK inhibitor, ZER + FAK inhibitor-treated cells, NF-β inhibitor, ZER + NF-β inhibitor, and untreated cells. The data in the present study suggest that ZER may exert its antimetastatic effects through inhibition of FAk/PI3k/NF-κB-uPA signaling pathway, thereby possibly representing a novel class of FAK inhibitors.

Zerumbone, a cyclic sesquiterpene, exerts antimitotic activity in HeLa cells through tubulin binding and exhibits synergistic activity with vinblastine and paclitaxel

Objectives

The aim of this study was to elucidate the antimitotic mechanism of zerumbone and to investigate its effect on the HeLa cells in combination with other mitotic blockers.

Materials and methods

HeLa cells and fluorescence microscopy were used to analyse the effect of zerumbone on cancer cell lines. Cellular internalization of zerumbone was investigated using FITC‐labelled zerumbone. The interaction of zerumbone with tubulin was characterized using fluorescence spectroscopy. The Chou and Talalay equation was used to calculate the combination index.

Results

Zerumbone selectively inhibited the proliferation of HeLa cells with an IC₅₀ of 14.2 ± 0.5 μmol/L through enhanced cellular uptake compared to the normal cell line L929. It induced a strong mitotic block with cells exhibiting bipolar spindles at the IC₅₀ and monopolar spindles at 30 μmol/L. Docking analysis indicated that tubulin is the principal target of zerumbone. In vitro studies indicated that it bound to goat brain tubulin with a Kd of 4 μmol/L and disrupted the assembly of tubulin into microtubules. Zerumbone and colchicine had partially overlapping binding site on tubulin. Zerumbone synergistically enhanced the anti‐proliferative activity of vinblastine and paclitaxel through augmented mitotic block.

Conclusion

Our data suggest that disruption of microtubule assembly dynamics is one of the mechanisms of the anti‐cancer activity of zerumbone and it can be used in combination therapy targeting cell division.

Zerumbone binding to estrogen receptors: an in-silico investigation

Breast cancer is the most frequent malignancy among females worldwide. Estrogen receptor (ER) mediate important pathophysiological signaling pathways induced by estrogens, and is regarded as a promising target for the treatment of breast cancer. Zerumbone (2,6,9,9-tetramethylcycloundeca-2,6,10-trien-1-one; ZER), a chemical constituent present in the Zingiber zerumbet is known to exhibit anti-breast cancer activity by modulating several proteins to induce apoptosis. Medicinal chemists usually exploit lead compounds of natural origin to develop molecules with improved pharmacological properties. Current study is intended to utilize molecular modeling techniques to investigate the interaction of ZER with estrogen receptors. AutoDock was used to predict the binding modes of ZER and target receptors. Stability of the ZER-ER complex was verified by molecular dynamics simulation using Desmond software. Docked ZER was further optimized by density functional theory (DFT) using Gaussian09 program. Analysis of docked conformations in terms of binding energy disclosed estrogen receptor-β (ERβ) as more promising than estrogen receptor-α (ERα). Evaluation of MD trajectories of ZER bound to both ERα and ERβ showed appreciable stability with minimum Cα-atom root mean square deviation shifts. DFT based global reactivity descriptors such as electron affinity, hardness, chemical potential, electronegativity and electrophilicity index, calculated from the energies of highest occupied and lowest unoccupied molecular orbitals underscored the electronic features governing viability of the ZER for interaction with the target receptors. In conclusion, these findings can be exploited to design and develop novel anticancer agents based on the lead compound, ZER.

Stimulation of the ATPase activity of Hsp90 by zerumbone modification of its cysteine residues destabilizes its clients and causes cytotoxicity

Hsp90 is an ATP-dependent molecular chaperone that assists folding and conformational maturation/maintenance of many proteins. It is a potential cancer drug target because it chaperones oncoproteins. A prokaryotic homolog of Hsp90 (HtpG) is essential for thermo-tolerance in some bacteria and virulence of zoonotic pathogens. To identify a new class of small molecules which target prokaryotic and eukaryotic Hsp90s, we studied the effects of a naturally occurring cyclic sesquiterpene, zerumbone, which inhibits proliferation of a wide variety of tumor cells, on the activity of Hsp90. Zerumbone enhanced the ATPase activity of cyanobacterial Hsp90 (Hsp90SE), yeast Hsp90, and human Hsp90α. It also enhanced the catalytic efficiency of Hsp90SE by greatly increasing kcat. Mass analysis showed that zerumbone binds to cysteine side chains of Hsp90SE covalently. Mutational studies identified 3 cysteine residues (one per each domain of Hsp90SE) that are involved in the enhancement, suggesting the presence of allosteric sites in the middle and C-terminal domains of Hsp90SE. Treatment of cyanobacterial cells with zerumbone caused them to become very temperature-sensitive, a phenotype reminiscent of cyanobacterial Hsp90 mutants, and also decreased the cellular level of linker polypeptides that are clients for Hsp90SE. Zerumbone showed cellular toxicity on cancer-derived mammalian cells by inducing apoptosis. In addition, zerumbone inhibited the binding of Hsp90/Cdc37 to client kinases. Altogether, we conclude that modification of cysteine residues of Hsp90 by zerumbone enhances its ATPase activity and inhibits physiological Hsp90 function. The activation of Hsp90 may provide new strategies to inhibit its chaperone function in cells.

Zerumbone inhibits epithelial-mesenchymal transition and cancer stem cells properties by inhibiting the β-catenin pathway through miR-200c

Colorectal cancer (CRC) is one of the most lethal and rampant human malignancies in the world. Zerumbone, a sesquiterpene isolated from subtropical ginger, has been found to exhibit an antitumor effect in various cancer types. However, the effect of Zerumbone on the biological properties of CRC, including epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) has not been fully elucidated. Here, we investigated the inhibitory action of Zerumbone on the EMT process, CSC markers, and the β-catenin signaling pathway in the presence or absence of miR-200c. The effect of Zerumbone on HCT-116 and SW-48 cells viability was examined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The effects of Zerumbone on EMT-related genes, CSCs markers, cell migration, invasion, sphere-forming, and β-catenin signaling pathway were explored. To evaluate the role of miR-200c in anticancer effects by Zerumbone, miR-200c was downregulated by LNA-anti-miR-200c. Zerumbone significantly inhibited cell viability, migration, invasion, and sphere-forming potential in HCT-116 and SW-48 cell lines. Zerumbone significantly suppressed the EMT and CSC properties as well as downregulated the β-catenin. Silencing of miR200c reduced the inhibitory effects of Zerumbone on EMT and CSCs in CRC cells. These data indicated that Zerumbone may be a promising candidate for reducing the risk of CRC progression by suppressing the β-catenin pathway via miR-200c.

Potential role of genipin in cancer therapy

Genipin, an aglycone derived from the iridoid glycoside, geniposide, is isolated and characterized from the extract of Gardenia jasminoides Ellis fruit (family Rubiaceae). It has long been used in traditional oriental medicine for the prevention and treatment of several inflammation driven diseases, including cancer. Genipin has been shown to have hepatoprotective activity acting as a potent antioxidant and inhibitor of mitochondrial uncoupling protein 2 (UCP2), and also reported to exert significant anticancer effects. It is an excellent crosslinking agent that helps to make novel sustained or delayed release nanoparticle formulations. In this review, we present the latest developments of genipin as an anticancer agent and briefly describe its diverse mechanism(s) of action. Several lines of evidence suggest that genipin is a potent inhibitor of UCP2, which functions as a tumor promoter in a variety of cancers, attenuates generation of reactive oxygen species and the expression of matrix metalloproteinase 2, as well as induces caspase-dependent apoptosis in vitro and in in vivo models. These finding suggests that genipin can serve as both a prominent anticancer agent as well as a potent crosslinking drug that may find useful application in several novel pharmaceutical formulations.

Zerumbone ameliorates high-fat diet-induced adiposity by restoring AMPK-regulated lipogenesis and microRNA-146b/SIRT1-mediated adipogenesis

Obesity is characterized by increased fat mass, as adipose tissue serves as a storage site for excess energy from food consumption. In obesity, altered lipid metabolism of adipose tissue, characterized by fatty acid uptake, de novo lipogenesis, and lipolysis, are induced. In this study, we examined the effect of zerumbone, a major sesquiterpene from wild ginger, on high-fat diet (HF)-induced obesity and dysregulated lipid metabolism in the white adipose tissues (WAT) of C57BL/6N mice. Dietary supplementation with zerumbone ameliorated HF-induced obesity and improved impaired lipid metabolism in WAT. Zerumbone additionally induced AMPK activation and phosphorylation of acetyl-CoA carboxylase, and effectively decreased adipogenic differentiation, in a concentration-dependent manner in the 3T3-L1 cells. Dysregulated microRNAs in obese WAT and adipocytes were examined, and zerumbone treatment was found to effectively reverse the robust upregulation of microRNA-146b. An increase in the levels of SIRT1, the direct target of microRNA-146b, was observed in zerumbone-treated differentiated adipocytes. This increase was additionally observed in WAT of zerumbone-supplemented mice. The antiadipogenic effect of zerumbone was found to be abolished in SIRT1-silenced 3T3-L1 cells. The increase in SIRT1 levels induced by zerumbone led to deacetylation of FOXO1 and PGC1α in WAT and differentiated 3T3-L1 cells. These findings indicate that zerumbone ameliorated diet-induced obesity and inhibited adipogenesis, and that the underlying mechanisms involved AMPK and the microRNA-146b/SIRT1 pathway. Zerumbone may represent a potential therapeutic candidate for the prevention and treatment of metabolic diseases, particularly obesity.

Zerumbone reduces proliferation of HCT116 colon cancer cells by inhibition of TNF-alpha

Zerumbone is a known anti-cancer herbal compound. However, the actual protein target is not fully understood or known. This investigation focus on the association of zerumbone in HCT116 colon cancer cell proliferation and its link with TNF-alpha. The study shows that with the increasing concentration of zerumbone, there was a reduction of HCT116 cells proliferation based on the cell line study and hence higher TNF-alpha inhibition based on the TNF-alpha assay. The study also emphasizes on the computational aspect by investigating the molecular docking analysis of zerumbone against TNF-alpha. The docked complex was further validated using molecular dynamics simulation studies. The docking analysis observed that alpha-beta unsaturated carbonyl scaffold is an important moiety for the anti-cancer activity of zerumbone. Furthermore, the DFT analysis also confirms the reactivity nature of zerumbone based on the frontier molecular orbital analysis.

Zerumbone, a Cyclic Sesquiterpene from Zingiber zerumbet Induces Apoptosis, Cell Cycle Arrest, and Antimigratory Effects in SW480 Colorectal Cancer Cells

Zerumbone isolated from the rhizomes of Zingiber zerumbet was investigated for the mechanisms by which it exhibits antiproliferative activity in colorectal cancer cells (SW480). The results indicated that the zerumbone suppressed cell growth and enhanced cell apoptosis. Exposure to zerumbone induced generation of reactive oxygen species, reduced the cellular antioxidant status, decreased mitochondrial membrane potential, and activated caspase 3, caspase 8, and caspase 9 (p < 0.001). It was also found that there was a decrease in the expression of Bcl 2 and elevation of Bax (p < 0.001) on exposure to zerumbone. Furthermore, treatment with 50, 75, and 100 μM zerumbone resulted in cell cycle arrest at the G2/M phase with a value of 17.2 ± 0.1, 19.63 ± 0.25, and 26.66 ± 0.25, respectively, and also distorted the microfilament network and effectively inhibited cellular migration.

Zerumbone targets the CXCR4-RhoA and PI3K-mTOR signaling axis to reduce motility and proliferation of oral cancer cells

BACKGROUND

The CXCR4-RhoA and PI3K-mTOR signaling pathways play crucial roles in the dissemination and tumorigenesis of oral squamous cell carcinoma (OSCC). Activation of these pathways have made them promising molecular targets in the treatment of OSCC. Zerumbone, a bioactive monocyclic sesquiterpene isolated from the rhizomes of tropical ginger, Zingiber zerumbet (L.) Roscoe ex Sm. has displayed promising anticancer properties with the ability to modulate multiple molecular targets involved in carcinogenesis. While the anticancer activities of zerumbone have been well explored across different types of cancer, the molecular mechanism of action of zerumbone in OSCC remains largely unknown.

PURPOSE

Here, we investigated whether OSCC cells were sensitive towards zerumbone treatment and further determined the molecular pathways involved in the mechanism of action.

METHODS

Cytotoxicity, anti-proliferative, anti-migratory and anti-invasive effects of zerumbone were tested on a panel of OSCC cell lines. The mechanism of action of zerumbone was investigated by analysing the effects on the CXCR4-RhoA and PI3K-mTOR pathways by western blotting.

RESULTS

Our panel of OSCC cells was broadly sensitive towards zerumbone with IC₅₀ values of less than 5 µM whereas normal keratinocyte cells were less responsive with IC₅₀ values of more than 25 µM. Representative OSCC cells revealed that zerumbone inhibited OSCC proliferation and induced cell cycle arrest and apoptosis. In addition, zerumbone treatment inhibited migration and invasion of OSCC cells, with concurrent suppression of endogenous CXCR4 protein expression in a time and dose-dependent manner. RhoA-pull down assay showed reduction in the expression of RhoA-GTP, suggesting the inactivation of RhoA by zerumbone. In association with this, zerumbone also inhibited the PI3K-mTOR pathway through the inactivation of Akt and S6 proteins.

CONCLUSION

We provide evidence that zerumbone could inhibit the activation of CXCR4-RhoA and PI3K-mTOR signaling pathways leading to the reduced cell viability of OSCC cells. Our results suggest that zerumbone is a promising phytoagent for development of new therapeutics for OSCC treatment.

The Role of Resveratrol in Cancer Therapy

Natural product compounds have recently attracted significant attention from the scientific community for their potent effects against inflammation-driven diseases, including cancer. A significant amount of research, including preclinical, clinical, and epidemiological studies, has indicated that dietary consumption of polyphenols, found at high levels in cereals, pulses, vegetables, and fruits, may prevent the evolution of an array of diseases, including cancer. Cancer development is a carefully orchestrated progression where normal cells acquires mutations in their genetic makeup, which cause the cells to continuously grow, colonize, and metastasize to other organs such as the liver, lungs, colon, and brain. Compounds that modulate these oncogenic processes can be considered as potential anti-cancer agents that may ultimately make it to clinical application. Resveratrol, a natural stilbene and a non-flavonoid polyphenol, is a phytoestrogen that possesses anti-oxidant, anti-inflammatory, cardioprotective, and anti-cancer properties. It has been reported that resveratrol can reverse multidrug resistance in cancer cells, and, when used in combination with clinically used drugs, it can sensitize cancer cells to standard chemotherapeutic agents. Several novel analogs of resveratrol have been developed with improved anti-cancer activity, bioavailability, and pharmacokinetic profile. The current focus of this review is resveratrol’s in vivo and in vitro effects in a variety of cancers, and intracellular molecular targets modulated by this polyphenol. This is also accompanied by a comprehensive update of the various clinical trials that have demonstrated it to be a promising therapeutic and chemopreventive agent.

Reprograming of Glucose Metabolism by Zerumbone Suppresses Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the most prevalent and highly aggressive liver malignancy with limited therapeutic options. Here, the therapeutic potential of zerumbone, a sesquiterpene derived from the ginger plant Zingiber zerumbet, against HCC was explored. Zerumbone inhibited proliferation and clonogenic survival of HCC cells in a dose-dependent manner by arresting cells at the G₂-M phase and inducing apoptosis. To elucidate the underlying molecular mechanisms, a phosphokinase array was performed that showed significant inhibition of the PI3K/AKT/mTOR and STAT3 signaling pathways in zerumbone-treated HCC cells. Gene expression profiling using microarray and analysis of microarray data by Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA) revealed that zerumbone treatment resulted in significant deregulation of genes regulating apoptosis, cell cycle, and metabolism. Indeed, tracing glucose metabolic pathways by growing HCC cells with ¹³C₆-glucose and measuring extracellular and intracellular metabolites by 2D nuclear magnetic resonance (NMR) spectroscopy showed a reduction in glucose consumption and reduced lactate production, suggesting glycolytic inhibition. In addition, zerumbone impeded shunting of glucose-6-phosphate through the pentose phosphate pathway, thereby forcing tumor cells to undergo cell-cycle arrest and apoptosis. Importantly, zerumbone treatment suppressed subcutaneous and orthotopic growth and lung metastasis of HCC xenografts in immunocompromised mice. In conclusion, these findings reveal a novel and potentially effective therapeutic strategy for HCC using a natural product that targets cancer cell metabolism.Implications: Dietary compounds, like zerumbone, that impact cell cycle, apoptosis, and metabolic processes may have therapeutic benefits for HCC patients. Mol Cancer Res; 16(2); 256-68. ©2017 AACR.

A Review of the Biomedical Applications of Zerumbone and the Techniques for Its Extraction from Ginger Rhizomes

Zerumbone (ZER) is a phytochemical isolated from the subtropical Zingiberaceae family and as a natural compound it has different biomedical properties such as antioxidant, anti-inflammatory anti-proliferative activity. ZER also has effects on angiogenesis and acts as an antitumor drug in the treatment of cancer, showing selective toxicity toward various cancer cell lines. Several techniques also have been established for extraction of ZER from the rhizomes of ginger. This review paper is an overview of recent research about different extraction methods and their efficiencies, in vivo and vitro investigations of ZER and also its prominent chemopreventive properties and treatment mechanisms. Most of the studies mentioned in this review paper may be useful use as a knowledge summary to explain ZER extraction and anticancer activities, which will show a way for the development of strategies in the treatment of malignancies using ZER.

Zerumbone Regulates DNA Repair Responding to Ionizing Radiation and Enhances Radiosensitivity of Human Prostatic Cancer Cells

Introduction. Radiation therapy using ionizing radiation is widely used for the treatment of prostate cancer. The intrinsic radiation sensitivity of cancer cells could be enhanced by modulating multiple factors including the capacity to repair DNA damage, especially double-strand breaks (DSBs). We aimed to examine the effect of zerumbone on radiation sensitivity and its protective effects against ionizing radiation–induced DSB in human prostate cancer cells. Materials and Methods. The human prostate cancer PC3 and DU145 cell lines were used. A colony formation assay was performed to analyze the radiation survival of cells. DNA histogram and generation of reactive oxygen species (ROS) were examined using flow cytometry. Western blotting was used to examine the expression of regulatory molecules related to DNA damage repair. Results. Pretreatment with zerumbone enhanced the radiation effect on prostate cancer cells. Zerumbone delayed the abrogation of radiation-induced expression of γ-H2AX, an indicator of DNA DSB. Zerumbone pretreatment markedly reduced ionizing radiation–induced upregulated expression of phosphorylated ATM (ataxia telangiectasia-mutated), which was partially reversed by the ATM agonist methyl methanesulfonate. Ionizing radiation augmented and zerumbone pretreatment reduced the expression of Jak2 and Stat3, which are involved in DNA damage repair signaling. No significant effect on the generation of ROS and expression of ATR was noted after zerumbone treatment. Conclusion: Zerumbone sensitized DU145 and PC3 prostatic cancer cells to ionizing radiation by modulating radiation-induced ATM activation during repair of DNA DSBs.

Assessing the anticancer effects associated with food products and/or nutraceuticals using in vitro and in vivo preclinical development-related pharmacological tests

This review is part of a special issue entitled "Role of dietary pattern, foods, nutrients and nutraceuticals in supporting cancer prevention and treatment" and describes a pharmacological strategy to determine the potential contribution of food-related components as anticancer agents against established cancer. Therefore, this review does not relate to chemoprevention, which is analysed in several other reviews in the current special issue, but rather focuses on the following: i) the biological events that currently represent barriers against the treatment of certain types of cancers, primarily metastatic cancers; ii) the in vitro and in vivo pharmacological pre-clinical tests that can be used to analyse the potential anticancer effects of food-related components; and iii) several examples of food-related components with anticancer effects. This review does not represent a catalogue-based listing of food-related components with more or less anticancer activity. By contrast, this review proposes an original pharmacological strategy that researchers can use to analyse the potential anticancer activity of any food-related component-e.g., by considering the crucial characteristics of cancer biological aggressiveness. This review also highlights that cancer patients undergoing chemotherapy should restrict the use of "food complements" without supervision by a medical nutritionist. By contrast, an equilibrated diet that includes the food-related components listed herein would be beneficial for cancer patients who are not undergoing chemotherapy.

Zerumbone reduced the inflammatory response of acute lung injury in endotoxin-treated mice via Akt-NFκB pathway

Zerumbone, a cyclic eleven-membered sesquiterpene, is the major component of the essential oil isolated from the wild ginger, Zingiber zerumbet. There are several beneficial pharmacological activities of zerumbone including anti-inflammatory, antioxidant, and anticancer activities. Acute lung injury (ALI) is an acute pulmonary inflammatory disorder with high morbidity and mortality rate. In present study, we aimed to investigate the protective effects and mechanisms of zerumbone on endotoxin, lipopolysaccharide (LPS)-induced ALI. Mice were pretreated with zerumbone at various concentrations for 30 min followed by intratracheal administration of LPS for 6 h. Pretreatment with zerumbone not only reduced leukocytes infiltration into the alveolar space but also inhibited lung edema in LPS-induced ALI. Decreased secretion of proinflammatory cytokines such as TNFα and IL-6 caused by LPS were reversed by zerumbone. LPS-induced expressions of proinflammatory mediators, iNOS and COX-2, were inhibited by zerumbone. In addition, NFκB activation and Akt phosphorylation were inhibited by zerumbone in LPS-induced ALI. All these results suggested that the protective mechanisms of zerumbone on endotoxin-induced ALI were via inhibition of Akt-NFκB activation.

Zerumbone inhibits melanoma cell proliferation and migration by altering mitochondrial functions

It has been reported that zerumbone (ZER) has marked effects on the regulation of cell proliferation and migration in multiple types of cancer, and has anti-cancer effects on various types of malignant cell. However, the effects and underlying molecular mechanisms of treatment with ZER on melanoma cells remain unclear. In the present study, the effect of treatment with ZER on the proliferation, migration and mitochondrial function of the human melanoma cell line CHL-1 was investigated. The results of the present study indicated that treatment with ZER significantly inhibited CHL-1 cell proliferation (P<0.001). Cell migration analysis further demonstrated that ZER inhibited the migration of CHL-1 cells (P<0.001). Treatment with ZER significantly increased cellular reactive oxygen species levels (P<0.001), reduced matrix membrane potential (P<0.001), decreased ATP (P<0.001) and mitochondrial DNA (P<0.001) levels, and decreased mitochondrial transcription factor A mRNA levels (P=0.002). The results of the present study suggested that the inhibition of proliferation and migration was mediated by altered mitochondrial function. In conclusion, the results of the present study suggested that ZER has chemotherapeutic effects on human melanoma cells by altering mitochondrial function.

Exploring the immunomodulatory and anticancer properties of zerumbone

Plant-derived immunomodulators and anti-cancer agents have attracted a lot of interest from natural product scientists for their efficacy and safety, and their significant contribution towards understanding targeted drug action and drug delivery mechanisms.

Chemotherapeutic effect of Zerumbone on melanoma cells through mitochondria-mediated pathways

BACKGROUND

Zerumbone (ZER) is a phytochemical that appears to regulate cell proliferation and apoptosis. It has been reported to have an anti-tumour effect in various malignant cells; however, the effect and the mechanism of ZER on melanoma cells needs to be clarified.

AIM

To explore whether ZER has an effect on human melanoma cells and to identify the mechanisms involved.

METHODS

We determined the chemotherapeutic action of ZER on the human malignant melanoma (MM) A375 cell line by CCK-8 immunohistochemistry, Hoechst 33342 staining and flow cytometry analysis. We also investigated the signalling pathways by which ZER induces apoptosis in A375 cells, using western blotting, reverse transcription PCR and caspase-3 activity analysis.

RESULTS

ZER induced significant cytotoxic action in A375 cells. Hoechst 33342 staining and flow cytometry apoptosis analysis further demonstrated that ZER induced apoptosis in A375 cells. Treatment with ZER downregulated Bcl-2 gene and protein levels, upregulated Bax and Cytochrome c gene and protein levels, and activated Caspase-3.

CONCLUSIONS

ZER might have a chemotherapeutic effect on human melanoma cells through mitochondria-mediated pathways.

Antiproliferative and anti-inflammatory polyhydroxylated spirostanol saponins from Tupistra chinensis

Tupistra chinensis is widely distributed in southwestern China and its rhizome is a famous folk medicine for the treatment of carbuncles and pharyngitis. Its chemical identity of potent antiproliferative and anti-inflammatory constituents has been carried out in this study. Twenty-three polyhydroxylated spirostanol saponins, including nine novels, were isolated and identified. The new spirostanol saponins were elucidated as spirost-25(27)-en-1β,2β,3β,4β,5β-pentol-2-O-β-D-xylopyranoside (1), spirost-25(27)- en-1β,2β,3β,4β,5β-pentol-2-O-α-L-arabinopyranoside (2), spirost-25(27)-en- 1β,3α,5β-triol (12), spirost-25(27)-en-1β,3α,4β,5β,6β-pentol (13), spirost-25(27)-en- 1β,2β,3β,5β-tetraol-5-O-β-D-glucopyranoside (16), 5β-spirost-25(27)-en-1β,3β-diol- 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranoside (17), (25R)-5β-spirostan- 1β,3β-diol-3-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranoside (18), (25R)-5β- spirostan-1β,3β-diol-3-O-β-D-fructofuranosyl-(2 → 6)-β-D-glucopyranoside (19), 5β-spirost-25(27)-en-3β-ol-3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranoside (20). The antiproliferative effects against seven human cancer cell lines and inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in a macrophage cell line RAW 264.7 were assayed for all the isolated compounds. Compounds 17, 19 and 21 exhibited potential antiproliferative activities against all of human cancer cell lines tested. Compounds 21 showed significant inhibition on NO production with IC₅₀ values of 11.5 μM. These results showed that the spirostanol saponins isolated from the dried rhizomes of T. chinensis have potent antiproliferative and anti-inflammatory activities and T. chinensis might be used as anticancer and.anti-inflammatory supplement.

Zerumbone, a Sesquiterpene, Controls Proliferation and Induces Cell Cycle Arrest in Human Laryngeal Carcinoma Cell Line Hep-2

Zerumbone (ZER), a sesquiterpene found in Zingiber zerumbet Smith, has been shown to possess antiproliferative, anticancer, antioxidant, and anti-inflammatory activity against various types of human carcinoma. The molecular mechanism by which ZER mediates its activity against many cancer types is revealed by many studies. Upregulation of proapoptotic molecules and suppression of antiapoptotic gene expression are few of the mechanisms by which ZER mediates its effect. The present study is focused on investigating the effect of ZER on proliferation of laryngeal carcinoma cells (Hep-2). MTT assay results showed that ZER (0.01-100 μM) induced death of Hep-2 cells in a concentration-dependent manner; significant suppression of proliferation of Hep-2 cells was seen with a IC50 value of 15 µM. ZER at a concentration of 15 and 30 μM for 48 h showed early signs of apoptosis as evidenced by confocal microscopy imaging. Flow cytometry studies showed that ZER induced cell cycle arrest. ZER arrested Hep-2 proliferation at S and G2/M phases of cell cycle. In conclusion, these results indicate that ZER has antiproliferative effect and arrests cell cycle in Hep-2 cells in vitro. This could be a potential anticancer drug against laryngeal carcinoma.

Antinociceptive and Anti-Inflammatory Effects of Zerumbone against Mono-Iodoacetate-Induced Arthritis

The fresh rhizome of Zingiber zerumbet Smith (Zingiberaceae) is used as a food flavoring and also serves as a folk medicine as an antipyretic and for analgesics in Taiwan. Zerumbone, a monocyclic sesquiterpene was isolated from the rhizome of Z. zerumbet and is the major active compound. In this study, the anti-inflammatory and antinociceptive effects of zerumbone on arthritis were explored using in vitro and in vivo models. Results showed that zerumbone inhibited inducible nitric oxide (NO) synthase (iNOS), cyclooxygenase (COX)-2 expressions, and NO and prostaglandin E₂ (PGE₂) production, but induced heme oxygenase (HO)-1 expression in a dose-dependent manner in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. When zerumbone was co-treated with an HO-1 inhibitor (tin protoporphyrin (SnPP)), the NO inhibitory effects of zerumbone were recovered. The above results suggest that zerumbone inhibited iNOS and COX-2 through induction of the HO-1 pathway. Moreover, matrix metalloproteinase (MMP)-13 and COX-2 expressions of interleukin (IL)-1β-stimulated primary rat chondrocytes were inhibited by zerumbone. In an in vivo assay, an acetic acid-induced writhing response in mice was significantly reduced by treatment with zerumbone. Furthermore, zerumbone reduced paw edema and the pain response in a mono-iodoacetate (MIA)-induced rat osteoarthritis model. Therefore, we suggest that zerumbone possesses anti-inflammatory and antinociceptive effects which indicate zerumbone could be a potential candidate for osteoarthritis treatment.

Zerumbone, a ginger sesquiterpene, induces apoptosis and autophagy in human hormone-refractory prostate cancers through tubulin binding and crosstalk between endoplasmic reticulum stress and mitochondrial insult

Zerumbone, a natural monocyclic sesquiterpene, is the main component of the tropical plant Zingiber zerumbet Smith. Zerumbone induced antiproliferative and apoptotic effects against PC-3 and DU-145, two human hormone-refractory prostate cancer (HRPC) cell lines. Zerumbone inhibited microtubule assembly and induced an increase of MPM-2 expression (specific recognition of mitotic proteins). It also caused an increase of phosphorylation of Bcl-2 and Bcl-xL, two key events in tubulin-binding effect, indicating tubulin-binding capability and mitotic arrest to zerumbone action. Furthermore, zerumbone induced several cellular effects distinct from tubulin-binding properties. First, zerumbone significantly increased, while paclitaxel (as a tubulin-binding control) decreased, Mcl-1 protein expression. Second, paclitaxel but not zerumbone induced Cdk1 activity. Third, zerumbone other than paclitaxel induced Cdc25C downregulation. The data suggest that, in addition to targeting tubulin/microtubule, zerumbone may act on other targets for signaling transduction. Zerumbone induced mitochondrial damage and endoplasmic reticulum (ER) stress as evidenced by the loss of mitochondrial membrane potential and upregulation of GRP-78 and CHOP/GADD153 expression. Zerumbone induced an increase of intracellular Ca(2+) levels, a crosstalk marker between ER stress and mitochondrial insult, associated with the formation of active calpain I fragment. It induced apoptosis through a caspase-dependent way and caused autophagy as evidenced by dramatic LC3-II formation. In summary, the data suggest that zerumbone is a multiple targeting compound that inhibits tubulin assembly and induces a crosstalk between ER stress and mitochondrial insult, leading to apoptosis and autophagy in HRPCs.

Pyrrocidine A, a metabolite of endophytic fungi, has a potent apoptosis-inducing activity against HL60 cells through caspase activation via the Michael addition

Pyrrocidine A is a known antimicrobial compound produced by endophytic fungi and has a unique 13-membered macrocyclic alkaloid structure with an α,β-unsaturated carbonyl group. We have previously reported that pyrrocidine A shows potent cytotoxicity against human acute promyelocytic leukemia HL60 cells, and the activity is 70-fold higher than that of pyrrocidine B which is the analog lacking the α,β-unsaturated carbonyl group. Pyrrocidine A induced nuclear condensation, DNA fragmentation and caspase activation in HL60 cells. Since the DNA fragmentation was suppressed by pretreatment with the pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethylketone (z-VAD-fmk), caspase-mediated apoptosis contributes to pyrrocidine A-induced cytotoxicity. JFCR39 human cancer cells panel indicated that the mechanism of action of pyrrocidine A is different from other clinical anticancer drugs, and this compound broadly inhibited the growth of various cancer cell lines. The apoptosis induction by pyrrocidine A was suppressed by both N-acetyl-l-cysteine (NAC) and glutathione, both of which are thiol-containing antioxidants. Furthermore, pyrrocidine A directly bound to N-acetyl-l-cysteine methyl ester (NACM) through the Michael-type addition at the α,β-unsaturated carbonyl group and was detected by HPLC and liquid chromatography-ESI-tandem MS (LC-ESI-MS/MS) analyses. This indicates that this moiety is crucial for the potent apoptosis-inducing activity of pyrrocidine A.

Zerumbone inhibits growth of hormone refractory prostate cancer cells by inhibiting JAK2/STAT3 pathway and increases paclitaxel sensitivity

Zerumbone, a phytochemical isolated from Zingiber zerumbet has been shown previously to exhibit antineoplastic activity. But, the effect of zerumbone in prostate cancer has not been evaluated. Prostate cancer is frequently associated with elevated levels of interleukin-6 (IL-6), which exerts its oncogenic effects through activation of Janus kinase 2 (JAK2) followed by activation of the transcription factor STAT3 (signal transducer and activator of transcription 3). Here, we investigated whether the anticancer effects of zerumbone are mediated through inhibition of the JAK2/STAT3 signaling pathway and whether zerumbone can increase the paclitaxel (PTX) sensitivity of prostate cancer cells. Zerumbone exerted significant cytotoxicity of DU145 versus PC3 prostate cancer cells through cell cycle arrest at G0/G1 phase followed by apoptosis. Zerumbone selectively inhibited JAK2 in both DU145 and PC3 cells. However, the biological axis of IL-6/JAK2/STAT3 was inhibited only in DU145 cells as no STAT3 phosphorylation was detected in PC3 cells even after IL-6 stimulation. Other signaling pathways in DU145 cells remained unaffected. The expression of prostate cancer-associated genes, including cyclin D1, IL-6, COX2, and ETV1, was blocked. Zerumbone also synergistically increased the sensitivity to PTX. Further preclinical study might reveal the potential use of zerumbone as a chemotherapeutic agent for hormone refractory prostate cancer where IL-6/JAK2/STAT3 signaling is aberrantly active and may be combined with PTX.