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

Healthy Zerumbone: From Natural Sources to Strategies to Improve Its Bioavailability and Oral Administration

Zerumbone is a multifunctional compound with antimicrobial, antitumor, hyperalgesic, antioxidant and anti-inflammatory applications, and constitutes a point molecule for the future synthesis of derivatives with improved efficiency. This monocyclic sesquiterpenoid is found in high content in wild ginger (Zingiber zerumbet Smith), a perennial herb with economic importance as an ornamental as well as a medicinal plant. The presence of zerumbone is a distinctive feature that allows identification and differentiation from other species, not only in Zingiber, but also in Curcuma, Alpinia, Boesenbergia, Ethlingera and Ammomum spp., as well as related families (Costaceaee). To successfully use zerumbone in areas such as medicine, food and agriculture, further research on improving its low solubility and bioavailability, as well as its preservation, is a major current priority. In addition, despite its promising pharmacological activities, preclinical and clinical studies are required to demonstrate and evaluate the in vivo efficacy of zerumbone.

Differential mRNA expression in the induction of DNA damage, G2/M arrest, and cell death by zerumbone in HepG2/C3A cells

Zerumbone (ZER) is a phytochemical with antioxidant and antiproliferative properties. This study evaluated the cytoxicity of ZER combined with chemotherapeutic agents and the expression of mRNA genes related to cell cycle, cell death, xenobiotic metabolism, DNA damage, and endoplasmic reticulum (ER) stress in HepG2/C3A cells. ZER was cytotoxic (IC₅₀, 44.31 μM). ZER-induced apoptosis was related to BBC3 and ERN1 upregulation (ER stress), and its antiproliferative effects were attributable to MYC, IGF1, and NF-kB mRNA inhibition. ZER-induced G₂/M arrest and DNA damage was associated with mRNA expression of cell cycle (CDKN1A) and DNA damage (GADD45A) genes. Increased CYP1A2 and CYP2C19 mRNA expression suggested ZER metabolization, and reduced CYP1A1 and CYP2D6 expression indicated a longer time of action of ZER in the cell, enhancing its pharmacological effect. ZER downregulated TP53, PARP1, BIRC5 (apoptosis), and MAP1LC3A (autophagy). In apoptosis assay, the data of the association treatments with ZER suggested antagonism. In cytotoxicity assay, the data of the association treatments with ZER suggested synergism action to cisplatin and antagonism action to doxorubicin and 5-fluorouracil. Thus, ZER has potential for application in chemotherapy as it modulates mRNA targets; however, it may not have the desired efficiency when combined with other chemotherapeutic agents.

Exploring the anticancer activities of novel bioactive compounds derived from endophytic fungi: mechanisms of action, current challenges and future perspectives

Cancer is the second leading cause of death all around the world. The natural compounds derived from the endophytic flora of fungi are possible solutions to cancer treatment because they are safe for health, cost-effective, biocompatible and have fewer toxicity issues. The active ingredients in endophytic fungi that are responsible for anti-cancer activities are alkaloids, terpenoids, glycosides, saponin, peptides, steroids, phenols, quinones, and flavonoids. This review highlights the anti-cancer activities of entophytic fungus against human papillary thyroid carcinoma (IHH4), human pancreatic (PANC-1), ovarian (OVCAR-3), hepatic (HepG2), lung (A-549), human lymphoma (U937), human skin carcinoma (A431), breast (MCF-7), and Kaposi's sarcoma. The emerging evidence suggested that bioactive compounds isolated from endophytic fungi showed their anti-cancer activities by revealing the disturbance of the microtubule network caused by increased levels of Bax and Bcl-2 proteins that triggers cell cycle arrest at the G2-M phase, by inhibiting the DNA replication via binding with topoisomerase II, by regulating the activity of extracellular signal-regulated kinase and NF-kB, by evaluating the levels of p21, p27, and cyclins B/D1/E that led to cell death by apoptosis and cell cycle arrest. This review will assist readers in better comprehending bioactive chemicals and the beneficial interaction between the fungal endophytes and medicinal plants.

Evaluation of anti-methicillin-resistant Staphylococcus aureus property of zerumbone

CONTEXT AND OBJECTIVE

Zerumbone has been reported to exert anti-microbial effects, but the mechanism by which the compound exerts its action is not known. Thus, this study aimed to investigate the mechanism of action of zerumbone against methicillin-resistance Staphylococcus aureus (MRSA), using the atomic force microscopy (AFM), scanning electron microscopy (SEM), and flow cytometry techniques.

METHODS

MRSA (NCTC 13277) cell viability was determined using the microplate AlamarBlue assay. AFM and SEM were used to determine the morphology of zerumbone-treated MRSA cells. Flow cytometric analysis was used to determine the effect of zerumbone on bacterial membrane permeability and membrane potential, using the propidium iodide (PI) staining method, membrane potential-sensitive fluorescence probe, and DiBAC4(3) dye. DCFDA dye was used to determine the generation of reactive oxygen species (ROS) by MRSA.

RESULTS

Zerumbone significantly inhibited MRSA growth with a minimum inhibitory concentration (MIC) of 125 µg/ml. The AFM analysis showed that zerumbone caused leakage of cytoplasmic content from the bacterial cells. Ultrastructure analysis showed small colonies of the bacteria with pores on the membrane surface. There were increases in zerumbone-treated MRSA PI and DiBAC4(3) fluorescence, indicating an increase in cell membrane permeability and a decrease in membrane potential that culminated in the loss of membrane structural integrity and bacterial death. Based on DCFDA dye analysis, zerumbone also reduced ROS production by MRSA.

CONCLUSIONS

Zerumbone exerts anti-MRSA effects by causing membrane depolarization, increasing membrane permeability, and finally disrupting cell membrane and bacterial killing.

Cytotoxic mechanism of tioconazole involves cell cycle arrest at mitosis through inhibition of microtubule assembly

Tioconazole is one of the drugs used to treat topical mycotic infections. It exhibited severe toxicity during systemic administration; however, the molecular mechanism behind the cytotoxic effect was not well established. We employed HeLa cells as a model to investigate the molecular mechanism of its toxicity and discovered that tioconazole inhibited HeLa cell growth through mitotic block (37%). At the half-maximal inhibitory concentration (≈ 15 μM) tioconazole apparently depolymerized microtubules and caused defects in chromosomal congression at the metaphase plate. Tioconazole induced apoptosis and significantly hindered the migration of HeLa cells. Tioconazole bound to goat brain tubulin (K _d, 28.3 ± 0.5 μM) and inhibited the assembly of microtubules in the in vitro assays. We report for the first time that tioconazole binds near to the colchicine site, based on the evidence from in vitro tubulin competition experiment and computational analysis. The conformation of tubulin dimer was found to be "curved" upon binding with tioconazole in the MD simulation. Tioconazole in combination with vinblastine synergistically inhibited the growth of HeLa cells and augmented the percentage of mitotic block by synergistically inhibiting the assembly of microtubules. Our study indicates that the systemic adverse effects of tioconazole are partly due to its effects on microtubules and cell cycle arrest. Since tioconazole is well tolerated at the topical level, it could be developed as a topical anticancer agent in combination with other systemic anticancer drugs.

GRAPHICAL ABSTRACT

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10616-021-00516-w.

Securinine induces mitotic block in cancer cells by binding to tubulin and inhibiting microtubule assembly: A possible mechanistic basis for its anticancer activity

AIM

Analysis of the anticancer and antimitotic activity of the plant derived alkaloid securinine along with its effect on the organization of cellular microtubules as well as its binding with purified goat brain tubulin in-vitro.

MATERIALS AND METHODS

The cytotoxicity of securinine on different cell lines was conducted using SRB assay. The effect of securinine on the cellular microtubules was analyzed using immunofluorescence microscopy. The binding of securinine on purified goat brain tubulin was evaluated using fluorescent spectroscopy.

KEY FINDINGS

Securinine effectively prevented the proliferation of cervical, breast and lung cancer cells with an IC₅₀ of 6, 10 and 11 μM respectively and induced minimal toxicity in HEK cell line. Securinine at concentrations higher than IC₅₀ induced significant depolymerization in interphase and mitotic microtubules and it suppressed the reassembly of cold depolymerized spindle microtubules in HeLa cells. In the wound healing assay, securinine effectively suppressed the migration of HeLa cells to close the wound. Securinine bound to tubulin with a Kd of 9.7 μM and inhibited the assembly of tubulin into microtubules. The treatment with securinine induced a mitochondrial dependent ROS response in HeLa cells which enhanced the cytotoxic effect of securinine. The result from gene expression studies indicates that securinine induced apoptosis in MCF-7 cells through p53 dependent pathway.

SIGNIFICANCE

Considering the strong anticancer and anti-metastatic property and low toxicity in non-malignant cell lines, we suggest that securinine can be used as a chemotherapeutic drug either alone or in combination with other known anticancer molecules.

The natural anthraquinone dye purpurin exerts antibacterial activity by perturbing the FtsZ assembly

There is an increasing demand to discover novel antibacterial drugs to counter the ever-evolving genetic machinery of bacteria. The cell division protein FtsZ plays a vital role in bacterial cytokinesis and has been recognized as an effective antibacterial drug target. In this study, we have shown that the madder dye purpurin inhibited bacterial cytokinesis through perturbation of FtsZ assembly. Purpurin inhibited the growth of bacterial cells in a concentration-dependent manner and induced bacterial cell filamentation. Microscopy studies showed that it inhibited the localization of the Z ring at the midcell, and FtsZ was dispersed throughout the cells. Further, purpurin bound firmly to FtsZ with a dissociation constant of 11 µM and inhibited its assembly in vitro. It reduced the GTP hydrolysis by binding closer to the nucleotide-binding site of FtsZ. Purpurin inhibited the proliferation of mammalian cancer cells at higher concentrations without disturbing the polymerization of tubulin. The results collectively suggest that the natural anthraquinone purpurin can potently inhibit the growth of bacteria and serve as a lead molecule for the development of antibacterial agents.

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.

Sertaconazole induced toxicity in HeLa cells through mitotic arrest and inhibition of microtubule assembly

Econazole, miconazole, and sertaconazole, the structurally related azoles with imidazole moiety, were evaluated for their cytotoxicity and their ability to bind to mammalian tubulin. Our results indicated that sertaconazole and econazole bound to goat brain tubulin with a dissociation constant of 9 and 19 μM respectively, while miconazole did not bind to goat brain tubulin. Econazole, miconazole, and sertaconazole inhibited the proliferation of HeLa cells with an IC₅₀ of 28, 98, and 38 μM respectively with sertaconazole alone inducing a mitotic block in the treated cells. Since sertaconazole bound to goat brain tubulin with higher affinity and blocked the cells at mitosis, we hypothesized that its cytotoxic mechanism might involve inhibition of tubulin and econazole which did not block the cells at mitosis may have additional targets than tubulin. Sertaconazole inhibited the polymerization of tubulin in HeLa cells and the in vitro assembled goat brain tubulin. Competitive tubulin-binding assay using colchicine and computational simulation studies showed that sertaconazole bound closer to the colchicine site and induced the tubulin dimer to adopt a "bent" conformation which is incompetent for the polymerization. Results from RT-PCR analysis of the A549 cells treated with sertaconazole indicated activation of apoptosis. Sertaconazole significantly inhibited the migration of HeLa cells and showed synergistic antiproliferative potential with vinblastine. Collectively, the results suggest that sertaconazole which is already in clinical practice could be useful as a topical chemotherapy agent for the treatment of skin cancers in combination with other systemic anticancer agents.

Sulforaphane-cysteine downregulates CDK4 /CDK6 and inhibits tubulin polymerization contributing to cell cycle arrest and apoptosis in human glioblastoma cells

Here we demonstrated that sulforaphane-cysteine (SFN-Cys) regulated cell cycle-related protein expressions in G0/G1 and G2/M phases of U87MG cells via High Performance Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (HPLC-MS/MS) and proteomics analysis. Further, mRNA products of CDK4, CDK6 and α-tubulin were significantly higher in glioblastoma than those in normal tissues, and these results were significantly correlated to pathological grades and clinical prognosis via analyzing TCGA and CGGA databases. Furthermore, Western blot showed that SFN-Cys downregulated CDK4, CDK6 and p-Rb in a dose-dependent manner and these results were reversed by p-ERK1/2 blocker PD98059 in U87MG and U373MG cells. The reductions of CDK4, CDK6 and p-Rb were reversed by proteasome inhibitor MG132; similarly, the upregulation of 26S proteasome by SFN-Cys was reversed by PD98059. Interestingly, SFN-Cys decreased CDK4 and CDK6 by phosphorylated ERK1/2-caused proteasomal degradation resulting in decreased Rb phosphorylation contributing to cell cycle arrest in G0/G1 phase. Besides, Western blot showed that SFN-Cys downregulated α-tubulin resulting in microtubule disruption and aggregation, and cell cycle arrest in G2/M phase and apoptosis. These results might help us understand the molecular etiology of glioblastoma progression to establish brand-new anti-cancer therapies.

Zerumbone ameliorates behavioral impairments and neuropathology in transgenic APP/PS1 mice by suppressing MAPK signaling

Background

Alzheimer’s disease (AD) is a major clinical problem, but there is a distinct lack of effective therapeutic drugs for this disease. We investigated the potential therapeutic effects of zerumbone, a subtropical ginger sesquiterpene, in transgenic APP/PS1 mice, rodent models of AD which exhibit cerebral amyloidosis and neuroinflammation.

Methods

The N9 microglial cell line and primary microglial cells were cultured to investigate the effects of zerumbone on microglia. APP/PS1 mice were treated with zerumbone, and non-cognitive and cognitive behavioral impairments were assessed and compared between the treatment and control groups. The animals were then sacrificed, and tissues were collected for further analysis. The potential therapeutic mechanism of zerumbone and the signaling pathways involved were also investigated by RT-PCR, western blot, nitric oxide detection, enzyme-linked immunosorbent assay, immunohistochemistry, immunofluorescence, and flow cytometry analysis.

Results

Zerumbone suppressed the expression of pro-inflammatory cytokines and induced a switch in microglial phenotype from the classic inflammatory phenotype to the alternative anti-inflammatory phenotype by inhibiting the mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B signaling pathway in vitro. After a treatment period of 20 days, zerumbone significantly ameliorated deficits in both non-cognitive and cognitive behaviors in transgenic APP/PS1 mice. Zerumbone significantly reduced β-amyloid deposition and attenuated pro-inflammatory microglial activation in the cortex and hippocampus. Interestingly, zerumbone significantly increased the proportion of anti-inflammatory microglia among all activated microglia, potentially contributing to reduced β-amyloid deposition by enhancing phagocytosis. Meanwhile, zerumbone also reduced the expression of key molecules of the MAPK pathway, such as p38 and extracellular signal-regulated kinase.

Conclusions

Overall, zerumbone effectively ameliorated behavioral impairments, attenuated neuroinflammation, and reduced β-amyloid deposition in transgenic APP/PS1 mice. Zerumbone exhibited substantial anti-inflammatory activity in microglial cells and induced a phenotypic switch in microglia from the pro-inflammatory phenotype to the anti-inflammatory phenotype by inhibiting the MAPK signaling pathway, which may play an important role in its neuroprotective effects. Our results suggest that zerumbone is a potential therapeutic agent for human neuroinflammatory and neurodegenerative diseases, in particular AD.

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.

The function of histone acetylation in cervical cancer development

Cervical cancer is the fourth most common female cancer in the world. It is well known that cervical cancer is closely related to high-risk human papillomavirus (HPV) infection. However, epigenetics has increasingly been recognized for its role in tumorigenesis. Epigenetics refers to changes in gene expression levels based on non-gene sequence changes, primarily through transcription or translation of genes regulation, thus affecting its function and characteristics. Typical post-translational modifications (PTMs) include acetylation, propionylation, butyrylation, malonylation and succinylation, among which the acetylation modification of lysine sites has been studied more clearly so far. The acetylation modification of lysine residues in proteins is involved in many aspects of cellular life activities, including carbon metabolism, transcriptional regulation, amino acid metabolism and so on. In this review, we summarize the latest discoveries on cervical cancer development arising from the aspect of acetylation, especially histone acetylation.

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.