Zerumbone causes Bax- and Bak-mediated apoptosis in human breast cancer cells and inhibits orthotopic xenograft growth in vivo

Anti-cancer potential of zerumbone in cancer and glioma: current trends and future perspectives

Plant-derived immunomodulators and antitumor factors have appealed lots of attention from natural product scientists for their efficiency and safety and their important contribution to well-designed targeted drug action and delivery mechanisms. Zerumbone (ZER), the chief component of Zingiber zerumbet rhizomes, has been examined for its wide-spectrum in the treatment of multi-targeted diseases. The rhizomes have been used as food flavoring agents in numerous cuisines and in flora medication. Numerous in vivo and in vitro experiments have prepared confirmation of ZER as a potent immunomodulator as well as a potential anti-tumor agent. This review is an interesting compilation of all the important results of the research carried out to date to investigate the immunomodulatory and anticancer properties of ZER. The ultimate goal of this comprehensive review is to supply updated information and a crucial evaluation on ZER, including its chemistry and immunomodulating and antitumour properties, which may be of principal importance to supply a novel pathway for subsequent investigation to discover new agents to treat cancers and immune-related sickness. In addition, updated information on the toxicology of ZER has been summarized to support its safety profile.

Cellular and molecular antiproliferative effects in 2D monolayer and 3D-cultivated HT-29 cells treated with zerumbone

Zerumbone (ZER) is a phytochemical isolated from plants of the Zingiberaceae family. Numerous studies have demonstrated its diverse pharmacological properties, particularly its potent antitumorigenic activity. This study aimed to assess the antiproliferative effects of ZER on HT-29 cells cultivated in both two-dimensional (2D) monolayer and three-dimensional (3D) spheroid culture systems. The evaluation of growth (size), cell death, and cell cycle arrest in 3D spheroid HT-29 cells was correlated with mRNA expression data. Treatment of 2D cells revealed that ZER exhibited cytotoxicity at concentrations above 30 µM, and an IC50 of 83.54 µM (24-h post-ZER treatment) effectively suppressed cell migration. In the 3D model, ZER induced an increase in spheroid volume over a 72-h period attributed to disaggregation and reconfiguration of characteristic zones. Analysis of cell death demonstrated a significant rise in apoptotic cells after 24 h of ZER treatment, along with cell cycle arrest in the G1 phase. Furthermore, ZER treatment resulted in alterations in mRNA expression, affecting key signaling pathways involved in cell death (BCL2 and BBC3), endoplasmic reticulum stress (ERN1), DNA damage (GADD45A), cell cycle regulation (CDKN1A, NFKB1, MYC, and TP53), and autophagy (BECN1 and SQSTM1). These findings suggested that ZER holds promise as a potential candidate for the development of novel anticancer agents that can modulate crucial cell signaling pathways. Additionally, the use of the 3D culture system proved to be a valuable tool in our investigation.

Essential oils and their nanoformulations for breast cancer therapy

Breast Cancer (BC) is the most prevalent type of cancer in the world. Current treatments include surgery, radiation, and chemotherapy but often are associated with high toxicity to normal tissues, chemoresistance, and relapse. Thus, developing novel therapies which could combat these limitations is essential for effective treatment. In this context, phytochemicals are increasingly getting popular due to their safety profile, ability to efficiently target tumors, and circumvent limitations of existing treatments. Essential Oils (EOs) are mixtures of various phytochemicals which have shown potential anticancer activity in preclinical BC models. However, their clinical translation is limited by factors such as high volatility, low stability, and poor solubility. Nanotechnology has facilitated their encapsulation in a variety of nanostructures and proven to overcome these limitations. In this review, we have efficiently summarized the current knowledge on the anticancer effect of EOs and constituents in both in in vitro and in in vivo BC models. Further, we also provide a descriptive account on the potential of nanotechnology in enhancing the anti-BC activity of EOs and their constituents. The papers discussed in this review were selected using the keywords "antiproliferative Essential Oils in breast cancer," "anticancer activity of Essential Oil in breast cancer," and "cytotoxicity of Essential Oils in breast cancer" performed in PubMed and ScienceDirect databases.

Facts and prospects of peptide in targeted therapy and immune regulation against triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Due to the lack of specific therapeutic targets, treatment options are limited, and the recurrence and metastasis rate is high, the overall survival of patients is poor. However, with the discovery of some new targets and the corresponding immune regulation after targeting these targets, TNBC has a new hope in treatment. The peptide has a simple structure, strong binding affinity, and high stability, and has great potential in targeted therapy and immune regulation against TNBC. This review will discuss how single peptides and peptide combinations target triple-negative breast cancer to exert immunomodulatory effects. Among them, single peptides target specific receptors on TNBC cells, act as decoys to target key ligands in the regulatory pathway, and target TME-related cells. The combinations of peptides work in the form of cancer vaccines, engineered exosomes, microRNAs and other immune-related molecular pathways, immune checkpoint inhibitors, chimeric antigen receptor T cells, and drug-peptide conjugates. This article is mainly dedicated to exploring new treatment methods for TNBC to improve the curative effect and prolong the survival time of patients.

Research Trend and Detailed Insights into the Molecular Mechanisms of Food Bioactive Compounds against Cancer: A Comprehensive Review with Special Emphasis on Probiotics

In an attempt to find a potential cure for cancer, scientists have been probing the efficacy of the food we eat and its bioactive components. Over the decades, there has been an exponentially increasing trend of research correlating food and cancer. This review explains the molecular mechanisms by which bioactive food components exhibit anticancer effects in several cancer models. These bioactive compounds are mainly plant based or microbiome based. While plants remain the primary source of these phytochemicals, little is known about probiotics, i.e., microbiome sources, and their relationships with cancer. Thus, the molecular mechanisms underlying the anticancer effect of probiotics are discussed in this review. The principal mode of cell death for most food bioactives is found to be apoptosis. Principal oncogenic signaling axes such as Akt/PI3K, JAK/STAT, and NF-κB seem to be modulated due to these bioactives along with certain novel targets that provide a platform for further oncogenic research. It has been observed that probiotics have an immunomodulatory effect leading to their chemopreventive actions. Various foods exhibit better efficacy as complete extracts than their individual phytochemicals, indicating an orchestrated effect of the food components. Combining bioactive agents with available chemotherapies helps synergize the anticancer action of both to overcome drug resistance. Novel techniques to deliver bioactive agents enhance their therapeutic response. Such combinations and novel approaches are also discussed in this review. Notably, most of the food components that have been studied for cancer have shown their efficacy in vivo. This bolsters the claims of these studies and, thus, provides us with hope of discovering anticancer agents in the food that we eat.

Anticancer bioactivity of zerumbone on pediatric rhabdomyosarcoma cells

PURPOSE

Natural products are generally regarded as safe and have been shown to mediate anticancer activities against a variety of cell types. Zerumbone is a natural cyclic sesquiterpene derived from the rhizome of Zingiber zerumbet, which has attracted extensive attention in the recent decade for anticancer activities. The present study investigates the in vitro effect of zerumbone on rhabdomyosarcoma cells.

METHODS

Two rhabdomyosarcoma cell lines (RD and RH30) were used as the model system. The growth inhibition of zerumbone was measured by MTT-assay, apoptosis via flow cytometry, gene expression by real-time PCR, the migration by transwell assay, and intracellular signaling by Western blotting.

RESULTS

Zerumbone shows anticancer effects on RD and RH30 cells in a dose-dependent manner via cell growth inhibition and induction of apoptosis. Exposure of RD and RH30 cells on zerumbone also resulted in a decrease of migration and downregulation of the hedgehog pathway.

CONCLUSIONS

Taken together, our study provided the first evidence that zerumbone imparted strong inhibitory and apoptotic effects on pediatric rhabdomyosarcoma cell lines and merit further investigation as a promising candidate for the anticancer therapy.

Tumor-Inhibitory Effects of Zerumbone Against HT-29 Human Colorectal Cancer Cells

Colorectal cancer (CRC) is the second cause of cancer-associated death globally. Recently, herbal medicinal products and, in particular, zerumbone have been widely studied and used for cancer treatment as they induce significant anti-cancer effects. However, there is limited information about the anti-cancer effects of zerumbone in CRC. Therefore, we aimed to investigate the in vitro anti-cancer effects of the zerumbone in CRC, focusing on cell apoptosis and migration. Anti-proliferative and anti-migratory effects of zerumbone on HT-29 cells were evaluated using MTT and scratch wound healing assay, respectively. Quantitative real-time PCR (qRT-PCR) was performed to determine the mRNA expression levels of migration and apoptosis-related genes. Apoptosis and cell cycle distribution were evaluated by flow cytometry. The intracellular level of reactive oxygen species (ROS) was measured using a ROS assay kit. Additionally, matrix metalloproteinase-2/-9 (MMP-2/-9) activity was determined using gelatin zymography. Zerumbone suppressed the viability of the HT-29 cells dose-dependently while having less cytotoxicity on normal NIH/3T3 cells. Zerumbone induced apoptosis in HT-29 cells and arrested the cell cycle in the G2/M phase. These effects were associated with alteration in the expression of apoptosis-related genes (up-regulation of Bax and down-regulation of Bcl-2 genes). Zerumbone also enhanced the generation of ROS in HT-29 cells. Furthermore, zerumbone significantly inhibited the migration of HT-29 cells and decreased MMP-2/-9 mRNA expression and activity. Our findings provide a potential use for zerumbone to induce apoptosis and suppress metastasis in HT-29 cells; thus, it could be developed as a promising natural agent for future CRC therapy.

Bioactive Compounds from Zingiber montanum and Their Pharmacological Activities with Focus on Zerumbone

The genus Zingiber consists of about 85 species and many of these species are used as food, spices, and medicines. One of the species, Zingiber montanum (J. Koenig) Link ex A. Dietr. is native to Southeast Asia and has been extensively used as traditional medicines and food. The aim of this review was to collect and critically analyze the scientific information about the bioactive compounds and pharmacological activities of Z. montanum with focus on one of the main components, zerumbone (ZER). Various studies have reported the analysis of volatile constituents of the essential oils from Z. montanum. Similarly, many phenylbutanoids, flavonoids and terpenes were also isolated from rhizomes. These essential oils, extracts and compounds showed potent antimicrobial, anti-inflammatory and antioxidant activities among others. Zerumbone has been studied widely for its anticancer, anti-inflammatory, and other pharmacological activities. Future studies should focus on the exploration of various pharmacological activities of other compounds including phenylbutanoids and flavonoids. Bioassay guided isolation may result in the separation of other active components from the extracts. Z. montanum could be a promising source for the development of pharmaceutical products and functional foods.

Anti-Cancer and Anti-Angiogenesis Activities of Zerumbone Isolated from Zingiber Zerumbet - A Systematic Review

Significant number of literatures has demonstrated the antiproliferative effect of Zerumbone and its role as anti-angiogenesis. The aims of this systematic review were to assess the anti-cancer effects of Zerumbone and the role of its antiangiogenic properties in treating cancer. Relevant articles were selected based on specific inclusion criteria. Articles chosen for this systematic review were between January 2008 and December 2018. Relevant articles were identified through an extensive search in Science Direct, PubMed, Google Scholar and Scopus. The literature searches of the electronic databases combined the following key words: anti-angiogenic, anticancer, Zerumbone and Zingiber zerumbet. Studies chosen for this review includes the following designs in vitro, in vivo and ex vivo. The initial literature search obtained a total of 352 related records and the final number of studies that met the inclusion criteria in the current review was 43 studies. In vitro studies were the commonest study design. Evidently, Zerumbone demonstrate a potential antiproliferative and antiangiogenic. The antiproliferative activities of Zerumbone was shown to induce by different signalling pathway. Zerumbone through its antiangiogenic effect play a great role in reducing invasion and metastasis. Some selected studies on Zerumbone were found to plague with limitation such as lack of toxic threshold value which may be needed for the clinical trials on this compound.

Mechanisms of Chemopreventive and Therapeutic Proprieties of Ginger Extracts in Cancer

Ginger (Zingiber officinale Roscoe, family: Zingiberaceae), originating in South-East Asia, is one of the most used spices and condiments for foods and beverages. It is also used in traditional medicine for many human disorders including fever, gastrointestinal complications, arthritis, rheumatism, hypertension, and various infectious diseases due to its anti-inflammatory, antioxidant, antimicrobial, and antiemetic properties. Intriguingly, many recent studies evidenced the potent chemopreventive characteristics of ginger extracts against different types of cancer. The aim of this work is to review the literature related to the use of ginger extracts as a chemotherapeutic agent and to structure the cellular and molecular mechanisms through which ginger acts in different cancer types. Data summarized from experiments (in vitro or in vivo) and clinical studies, evidenced in this review, show that ginger derivatives perpetrate its anti-tumor action through important mediators, involved in crucial cell processes, such as cell cycle arrest, induction of cancer cell death, misbalance of redox homeostasis, inhibition of cell proliferation, angiogenesis, migration, and dissemination of cancer cells.

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.

Comparison of Chemical Composition and Bioactivities of Essential Oils from Fresh and Dry Rhizomes of Zingiber zerumbet (L.) Smith

The chemical constituents and the antioxidant, antimicrobial, and cytotoxic activities of fresh rhizome essential oil (FR-EO) and dry rhizome essential oil (DR-EO) of Zingiber zerumbet (L.) Smith obtained from Southwest China were compared. Zerumbone was the predominant component in both FR-EO and DR-EO (75.0% and 41.9%, respectively). FR-EO, DR-EO, and zerumbone were all demonstrated to have significant antimicrobial capacity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Proteus vulgaris, with minimum inhibitory concentration (MIC) ranging from 31.25 to 156.25 μg/mL and minimum bactericidal concentration (MBC) ranging from 62.50 to 625.00 μg/mL. Zerumbone showed the strongest antimicrobial potential against all tested microorganisms compared with the fresh and dry rhizome essential oils. FR-EO was found to be more active than DR-EO against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Proteus vulgaris. FR-EO, DR-EO, and zerumbone all showed significant cytotoxic activity against K562, PC-3, and A549 human tumor cell lines in a time- and concentration-dependent manner. Zerumbone exhibited the strongest antiproliferative activity against all tested human tumor cell lines with an IC₅₀ of 4.21–11.09 μg/mL for 72 h incubation, as compared with the fresh and dry rhizome oils. The cytotoxic activity of FR-EO (IC₅₀: 10.48–14.51 μg/mL for 72 h) was found to be significantly higher (p < 0.05) than that of DR-EO (IC₅₀: 13.83–33.24 μg/mL for 72 h). FR-EO, DR-EO, and zerumbone exhibited selective cytotoxic activity to tumor cells, with a significantly low cytotoxicity to normal cells (MRC-5, IC₅₀: 56.98–147.29 μg/mL). However, FR-EO, DR-EO, and zerumbone all exhibited weak free-radical-scavenging activity according to DPPH and ABTS analysis. The findings highlighted in this study show that FR-EO provides appreciably higher content of the bioactive compound, zerumbone, and has higher antimicrobial and cytotoxic properties than DR-EO. Thus, fresh Z. zerumbet rhizome should be preferred in cosmetic, food, and pharmaceutical applications.

Gingers and Their Purified Components as Cancer Chemopreventative Agents

Chemoprevention by ingested substituents is the process through which nutraceuticals and/or their bioactive components antagonize carcinogenesis. Carcinogenesis is the course of action whereby a normal cell is transformed into a neoplastic cell. This latter action involves several steps, starting with initiation and followed by promotion and progression. Driving these stages is continued oxidative stress and inflammation, which in turn, causes a myriad of aberrant gene expressions and mutations within the transforming cell population and abnormal gene expressions by the cells within the surrounding lesion. Chemoprevention of cancer with bioreactive foods or their extracted/purified components occurs primarily via normalizing these inappropriate gene activities. Various foods/agents have been shown to affect different gene expressions. In this review, we discuss how the chemoprevention activities of gingers antagonize cancer development.

Zerumbone Induces Apoptosis in Breast Cancer Cells by Targeting αvβ3 Integrin upon Co-Administration with TP5-iRGD Peptide

Cell-penetrating peptides (CPPs) are highly promising tools to deliver therapeutic molecules into tumours. αVβ3 integrins are cell-matrix adhesion receptors, and are considered as an attractive target for anticancer therapies owing to their roles in the process of metastasis and angiogenesis. Therefore, this study aims to assess the effect of co-administration of zerumbone (ZER) and ZERencapsulated in hydroxypropyl-β-cyclodextrin with TP5-iRGD peptide towards cell cytotoxicity, apoptosis induction, and proliferation of normal and cancerous breast cells utilizing in vitro assays, as well as to study the molecular docking of ZER in complex with TP5-iRGD peptide. Cell viability assay findings indicated that ZER and ZERencapsulated in hydroxypropyl-β-cyclodextrin (ZER-HPβCD) inhibited the growth of estrogen receptor positivebreast cancer cells (ER⁺ MCF-7) at 72 h treatment with an inhibitory concentration (IC)₅₀ of 7.51 ± 0.2 and 5.08 ± 0.2 µg/mL, respectively, and inhibited the growth of triple negative breast cancer cells (MDA-MB-231) with an IC₅₀ of 14.96 ± 1.52 µg/mL and 12.18 ± 0.7 µg/mL, respectively. On the other hand, TP5-iRGD peptide showed no significant cytotoxicity on both cancer and normal cells. Interestingly, co-administration of TP5-iRGD peptide in MCF-7 cells reduced the IC₅₀ of ZER from 7.51 ± 0.2 µg/mL to 3.13 ± 0.7 µg/mL and reduced the IC₅₀ of ZER-HPβCD from 5.08 ± 0.2 µg/mL to 0.49 ± 0.004 µg/mL, indicating that the co-administration enhances the potency and increases the efficacy of ZER and ZER-HPβCD compounds. Acridine orange (AO)/propidium iodide (PI) staining under fluorescence microscopy showed evidence of early apoptosis after 72 h from the co-administration of ZER or ZER-HPβCD with TP5-iRGD peptide in MCF-7 breast cancer cells. The findings of the computational modelling experiment provide novel insights into the ZER interaction with integrin αvβ3 in the presence of TP5-iRGD, and this could explain why ZER has better antitumor activities when co-administered with TP5-iRGD peptide.

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, 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.

Zerumbone-Loaded Nanostructured Lipid Carrier Induces Apoptosis of Canine Mammary Adenocarcinoma Cells

Canine mammary gland tumor (CMT) is the most common tumor in intact female dog. Zerumbone (ZER) has promising anticancer properties, but plagued with poor water solubility, poor absorption, bioavailability, and delivery to target tissues. To solubilize, ZER was loaded into nanostructured lipid carrier (NLC) to produce ZER-loaded NLC (ZER-NLC). The objectives of this study were to determine the antiproliferative effect and the mode of cell death induced by ZER-NLC and ZER on a canine mammary gland tumor (CMT) adenocarcinoma primary cell line. There was no significant difference (p>0.05) between ZER-NLC and ZER treatments in the inhibition of CMT cell proliferation; thus, the loading of ZER into NLC did not compromise the cytotoxic effect of ZER. Microscopically, ZER-NLC- and ZER-treated CMT cells showed apoptotic cell morphology. ZER-NLC and ZER treatments significantly downregulated the antiapoptotic Bcl-2 and upregulated the proapoptotic Bax gene expressions in CMT cells. Both ZER-NLC and ZER-treated CMT cells showed significant (p<0.0001) increases in caspase-8, -9, and -3/7 protein activities. In conclusion, ZER-NLC induced CMT cell death via regulation of Bcl-2 and Bax gene expressions and caspase activations, indicating the involvement of both the intrinsic and extrinsic pathways of apoptosis. This study provided evidences for the potential of ZER-NLC as an anticanine mammary gland adenocarcinoma chemotherapy.

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.

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 modulates CD1d expression and lipid antigen presentation pathway in breast cancer cells

Natural Killer T (NKT) cells based cancer immunotherapy is an evolving area of cancer therapy, but tumors escape from this treatment modality by altering CD1d expression and its antigen presentation pathway. Here, we have studied the relation of CD1d expression in various breast cancer cell lines to their viability and progression. We observed a novel phenomenon that CD1d expression level increases with the progressive stage of the cancer. A small molecule, zerumbone (ZER) caused down-regulation of CD1d that was accompanied by breast cancer cell growth in vitro. The growth inhibitory effect of ZER against breast cancer cells was augmented by treatment with anti-CD1d mAb. This effect was mediated by G1-phase cell cycle arrest and apoptosis induction coupled with an increase in mitochondrial membrane depolarization. CD1d expression and cell proliferation were inhibited by both CD1d siRNA and ZER. The α-galactosylceramide, a ligand for CD1d, showed increased CD1d expression as well as cell proliferation which was opposite to the effects of ZER. This study shows that, CD1d overexpression is associated with the progressive stages of breast cancer and ZER could be an adjuvant to potentiate cancer immunotherapy.

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.

Elevated IL-1β expression induces invasiveness of triple negative breast cancer cells and is suppressed by zerumbone

Aberrant interleukin-1 beta (IL-1β) expression is associated with cancer development, metastasis, and poor prognosis. Here, we have investigated the regulatory mechanism of IL-1β expression, and the inhibitory effect of zerumbone (ZER) on IL-1β expression and IL-1β-induced signatures, including cell invasion and signaling activation in triple negative breast cancer (TNBC) cells. The basal IL-1β and cell invasiveness levels were significantly higher in TNBC cells, compared with non-TNBC cells. The invasiveness of TNBC cells was also increased following IL-1β treatment. In contrast, the invasiveness of TNBC cells was decreased following IL-1 receptor antagonist (IL-1RA) treatment. Additionally, the basal IL-1β level and the invasiveness of TNBC cells were decreased by Bay11-7085. In contrast, overexpression of NF-κB (p65) caused an increase in IL-1β expression in TNBC cells. Our results showed that treatment with ZER decreased the basal IL-1β expression level, and the phosphorylation level of NF-κB, in TNBC cells. Furthermore, we found that ZER completely suppressed IL-1β-induced NF-κB phosphorylation, but did not suppress IL-1β-induced Akt phosphorylation, in TNBC cells. Our results also demonstrate that IL-1β-induced cell invasion is suppressed by ZER in TNBC cells. Taken together, we demonstrated that IL-1β expression is regulated by the NF-κB-dependent pathway, and that elevated IL-1β is directly influencing the invasiveness of TNBC cells. ZER down-regulates IL-1β expression through the inhibition of NF-κB activity, and then suppresses cell invasiveness of TNBC.

Zerumbone induces gastric cancer cells apoptosis: Involving cyclophilin A

Gastric cancer is one of the leading causes for cancer death. There is an urgent need to develop new therapeutic approaches targeting metastatic gastric cancer. It has been reported that zerumbone has the anti-cancer effects in various malignant cells. However, the effect and the mechanism of zerumbone on melanoma cells is still largely unknown. In the study, we determined the actions of zerumbone on the human gastric cancer cell line SGC-7901.We also observed the mechanism by which zerumbone induced gastric cancer cell apoptosis. Our data indicated that zerumbone significantly inhibited the growth of human gastric cancer cells in a dose-dependent manner and apoptosis was the main cause of decreased cell viability in zerumbone -treated cells. The treatment with zerumbone downregulated Cyp A and Bcl-2 levels, upregulated Bax levels, and caused Cytochrome c (Cyt-C) to release, activating Caspase-3. In summary, our study suggests that zerumbone mightinduced human gastric cancer cells apoptosis through down-regulating Cyp A and mitochondria-mediated pathways.

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.

Zerumbone Suppresses Osteopontin-Induced Cell Invasion Through Inhibiting the FAK/AKT/ROCK Pathway in Human Non-Small Cell Lung Cancer A549 Cells

Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer deaths in the United States and Korea. We have previously demonstrated that osteopontin (OPN) induces cell invasion through inactivating cofilin. Inactivation of cofilin is mediated by the FAK/AKT/Rho-associated kinase (ROCK) pathway in human nonsmall cell lung cancer (NSCLC) cells. Zerumbone (1) has been shown to exert anticancer activities. In this study, whether and how 1 affects OPN-induced cell invasion was determined in NSCLC A549 cells. Results from Boyden chamber assays suggested that OPN induced invasion of A549 cells and that 1 strongly suppressed this activity without affecting cell viability. Compound 1 effectively inhibited OPN-induced protein expression of ROCK1, the phosphorylation of LIM kinase 1 and 2 (LIMK1/2), and cofilin. In addition, immunofluorescence staining showed that OPN caused a significant increase in lamellipodia formation at the leading edge of cells. However, 1 dramatically decreased OPN-induced lamellipodia formation. Compound 1 impaired OPN-induced phosphorylation of FAK and AKT, as determined by Western blot analysis. Taken together, these results suggest that 1 causes considerable suppression of OPN-induced cell invasion through inhibiting the FAK/AKT/ROCK pathway in NSCLC A549 cells.

Possible Anticancer Mechanisms of Some Costus speciosus Active Ingredients Concerning Drug Discovery

Costus speciosus is native to South East Asia, especially found in India, Srilanka, Indonesia and Malaysia. C. speciosus have numerous therapeutic potentials against a wide variety of complains. The therapeutic properties of C. speciosus are attributed to the presence of various ingredients such as alkaloids, flavonoids, glycosides, phenols, saponins, sterols and sesquiterpenes. This review presented the past, present, and the future status of C. speciosus active ingredients to propose a future use as a potential anticancer agent. All possible up-regulation of cellular apoptotic molecules as p53, p21, p27, caspases, reactive oxygen species (ROS) generation and others attribute to the anticancer activity of C. speciosus along the down-regulation of anti-apoptotic agents such as Akt, Bcl2, NFKB, STAT3, JAK, MMPs, actin, surviving and vimentin. Eventually, we recommend further investigation of different C. speciosus extracts, using some active ingredients and evaluate the anticancer effect of these chemicals against different cancers.

Cancer prevention and therapy through the modulation of the tumor microenvironment

Cancer arises in the context of an in vivo tumor microenvironment. This microenvironment is both a cause and consequence of tumorigenesis. Tumor and host cells co-evolve dynamically through indirect and direct cellular interactions, eliciting multiscale effects on many biological programs, including cellular proliferation, growth, and metabolism, as well as angiogenesis and hypoxia and innate and adaptive immunity. Here we highlight specific biological processes that could be exploited as targets for the prevention and therapy of cancer. Specifically, we describe how inhibition of targets such as cholesterol synthesis and metabolites, reactive oxygen species and hypoxia, macrophage activation and conversion, indoleamine 2,3-dioxygenase regulation of dendritic cells, vascular endothelial growth factor regulation of angiogenesis, fibrosis inhibition, endoglin, and Janus kinase signaling emerge as examples of important potential nexuses in the regulation of tumorigenesis and the tumor microenvironment that can be targeted. We have also identified therapeutic agents as approaches, in particular natural products such as berberine, resveratrol, onionin A, epigallocatechin gallate, genistein, curcumin, naringenin, desoxyrhapontigenin, piperine, and zerumbone, that may warrant further investigation to target the tumor microenvironment for the treatment and/or prevention of cancer.

Sustained proliferation in cancer: Mechanisms and novel therapeutic targets

Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression.

A novel component from citrus, ginger, and mushroom family exhibits antitumor activity on human meningioma cells through suppressing the Wnt/β-catenin signaling pathway

Recurrent meningiomas constitute an uncommon but significant problem after standard (surgery and radiation) therapy failure. Current chemotherapies (hydroxyurea, RU-486, and interferon-α) are only of marginal benefit. There is an urgent need for more effective treatments for meningioma patients who have failed surgery and radiation therapy. Limonin, Tangeritin, Zerumbone, 6-Gingerol, Ganoderic Acid A, and Ganoderic Acid DM are some of the plant derivatives that have anti-tumorgenic properties and cause cell death in meningioma cells in vitro. Due to its ease of administration, long-term tolerability, and low incidence of long-term side effects, we explored its potential as a therapeutic agent against meningiomas by examining their efficacy in vitro against meningioma cells. Treatment effects were assessed using MTT assay, Western blot analysis, caspases assay, and DNA fragmentation assay. Results indicated that treatments of IOMM-Lee and CH157MN meningioma cells with Limonin, Tangeritin, Zerumbone, 6-Gingerol, Ganoderic Acid A, and Ganoderic Acid DM induced apoptosis with enhanced phosphorylation of glycogen synthase kinase 3 β (GSK3β) via inhibition of the Wnt5/β-catenin pathway. These drugs did not induce apoptosis in normal human neurons. Other events in apoptosis included downregulation of tetraspanin protein (TSPAN12), survival proteins (Bcl-XL and Mcl-1), and overexpression apoptotic factors (Bax and caspase-3). These results provide preliminary strong evidence that medicinal plants containing Limonin, Tangeritin, 6-Gingerol, Zerumbone, Ganoderic Acid A, and Ganoderic Acid DM can be applied to high-grade meningiomas as a therapeutic agent, and suggests that further in vivo studies are necessary to explore its potential as a therapeutic agent against malignant meningiomas.

Pin1-based diagnostic and therapeutic strategies for breast cancer

Pin1 is the only known cis-to-trans isomerase that recognizes the phosphorylated pThr/pSer-Pro motifs in many signaling molecules, playing unique roles in the pathogenesis of breast cancer. First, Pin1 is prevalently over-expressed in kinds of breast cancer cell lines and tissues, such as MDA-MB-231 cell, MCF-7 cell, Her2+, ERα+, and basal-like breast cancer subtypes. Second, Pin1 amplifies many oncogenic signaling pathways, inhibits multiple tumor suppressors, promotes the angiogenesis and metastasis of breast cancer cells, and enhances the resistance of breast cancer cells to anti-tumor medicines. Third, inhibiting Pin1 blocks most of these detrimental effects in a great number of breast cancer cell lines. These findings suggest Pin1 as a promising diagnostic biomarker as well as an efficient therapeutic target for breast cancer. It is strongly expected that a Pin1-positive subtype of breast cancers should be extremely concerned and that the therapeutic efficacy of Pin1 inhibitors on breast cancer patients should be evaluated as soon as possible. Nonetheless, Pin1-based therapeutic strategies for breast cancer still deserve some debates. Hence, we give the predictions of several important issues, such as application precondition, side effects, and personalized medication, when Pin1 inhibitors are used in the breast cancer therapy. These proposals are meaningful for the further development of Pin1-based diagnostic and therapeutic strategies in order to conquer breast cancer.

Notch2 activation is protective against anticancer effects of zerumbone in human breast cancer cells

We showed previously that zerumbone (ZER), a sesquiterpene isolated from subtropical ginger, inhibited in vitro (MCF-7 and MDA-MB-231cells) and in vivo (MDA-MB-231 cells) growth of human breast cancer cells in association with apoptosis induction. Here, we investigated the role of Notch receptors in anticancer effects of ZER (cell migration inhibition and apoptosis induction) using breast cancer cells. Western blotting was performed to determine protein expression changes. Effect of ZER on transcriptional activity of Notch was assessed by luciferase reporter assays. Transfection with small hairpin RNA or small interfering RNA was performed for knockdown of Notch2 or Presenilin-1 protein. Cell migration and apoptosis were quantitated by Boyden chamber assay and flow cytometry, respectively. Exposure of MDA-MB-231, MCF-7, and SUM159 cells to ZER resulted in increased cleavage of Notch2 in each cell line. On the other hand, levels of cleaved Notch1 and Notch4 proteins were decreased following ZER treatment. Increased cleavage of Notch2 in ZER-treated cells was accompanied by induction of Presenilin-1 protein and transcriptional activation of Notch. Inhibition of cell migration as well as apoptosis induction resulting from ZER exposure was significantly augmented by knockdown of Notch2 protein. ZER-mediated cleavage of Notch2 protein in MDA-MB-231 cells was markedly attenuated upon RNA interference of Presenilin-1. Knockdown of Presenilin-1 protein also resulted in escalation of ZER-induced apoptosis. The present study indicates that Notch2 activation by ZER inhibits its proapoptotic and anti-migratory response at least in breast cancer cells.

Assessment of cell cycle phase-specific effects of zerumbone on mitotically synchronous surface cultures of Physarum polycephalum

Zerumbone, a natural cyclic sesquiterpene, has been the focus of recent research as it has been found to exhibit selective toxicity towards cancer cells compared to normal cells. Studies on the cell cycle phase-specific effects of this interesting compound, however, remain sparse. Hence, concentration and time-dependent effects of zerumbone were evaluated employing a suitable model system, the naturally synchronous surface cultures of Physarum polycephalum. Zerumbone treatment in S, early, and late G2 phases resulted in G2 arrest. Early G2 phase exhibited the highest sensitivity (P < 0.001) to the compound. Protein profiles showed a complete inhibition of cyclin B1 expression following zerumbone treatment. Furthermore, FACS and comet analysis revealed that zerumbone inhibited DNA synthesis (P < 0.001) without being genotoxic at the concentrations tested. Differential display of mRNA showed distinct zerumbone-induced variations in transcript profiles, an analysis of which suggested a likely link between cellular networks involving stress-related gene expression and G2 arrest in P. polycephalum.

Biomedical properties of a natural dietary plant metabolite, zerumbone, in cancer therapy and chemoprevention trials

Zerumbone (ZER) is a naturally occurring dietary compound, present in many natural foods consumed today. The compound derived from several plant species of the Zingiberaceae family that has been found to possess multiple biomedical properties, such as antiproliferative, antioxidant, anti-inflammatory, and anticancer activities. However, evidence of efficacy is sparse, pointing to the need for a more systematic review for assessing scientific evidence to support therapeutic claims made for ZER and to identify future research needs. This review provides an updated overview of in vitro and in vivo investigations of ZER, its cancer chemopreventive properties, and mechanisms of action. Therapeutic effects of ZER were found to be scientifically plausible and could be explained partially by in vivo and in vitro pharmacological activities. Much of the research outlined in this paper will serve as a foundation to explain ZER anticancer bioactivity, which will open the door for the development of strategies in the treatment of malignancies using ZER.

Abrogation of STAT3 signaling cascade by zerumbone inhibits proliferation and induces apoptosis in renal cell carcinoma xenograft mouse model

Persistent activation of signal transducer and activator of transcription 3 (STAT3) is one of the characteristic features of renal cell carcinoma (RCC) and often linked to its deregulated proliferation, survival, and angiogenesis. In the present report, we investigated whether zerumbone, a sesquiterpene, exerts its anticancer effect through modulation of STAT3 activation pathway. The pharmacological effect of zerumbone on STAT3 activation, associated protein kinases and phosphatase, and apoptosis was investigated using both RCC cell lines and xenograft mouse model. We observed that zerumbone suppressed STAT3 activation in a dose- and time-dependent manner in RCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, Janus-activated kinase 1, and Janus-activated kinase 2. Pervanadate treatment reversed zerumbone-induced downregulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that zerumbone induced the expression of tyrosine phosphatase SHP-1 that correlated with its ability to inhibit STAT3 activation. Interestingly, deletion of SHP-1 gene by siRNA abolished the ability of zerumbone to inhibit STAT3 activation. The inhibition of STAT3 activation by zerumbone also caused the suppression of the gene products involved in proliferation, survival, and angiogenesis. Finally, when administered i.p., zerumbone inhibited STAT3 activation in tumor tissues and the growth of human RCC xenograft tumors in athymic nu/nu mice without any side effects. Overall, our results suggest for the first time that zerumbone is a novel blocker of STAT3 signaling cascade and thus has an enormous potential for the treatment of RCC and other solid tumors.