Zoledronic acid produces antitumor effects on mesothelioma through apoptosis and S-phase arrest in p53-independent and Ras prenylation-independent manners

Blood cell DNA methylation biomarkers in preclinical malignant pleural mesothelioma: The EPIC prospective cohort

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer mainly caused by asbestos exposure. Specific and sensitive noninvasive biomarkers may facilitate and enhance screening programs for the early detection of cancer. We investigated DNA methylation (DNAm) profiles in MPM prediagnostic blood samples in a case-control study nested in the European Prospective Investigation into Cancer and nutrition (EPIC) cohort, aiming to characterise DNAm biomarkers associated with MPM. From the EPIC cohort, we included samples from 135 participants who developed MPM during 20 years of follow-up and from 135 matched, cancer-free, controls. For the discovery phase we selected EPIC participants who developed MPM within 5 years from enrolment (n = 36) with matched controls. We identified nine differentially methylated CpGs, selected by 10-fold cross-validation and correlation analyses: cg25755428 (MRI1), cg20389709 (KLF11), cg23870316, cg13862711 (LHX6), cg06417478 (HOOK2), cg00667948, cg01879420 (AMD1), cg25317025 (RPL17) and cg06205333 (RAP1A). Receiver operating characteristic (ROC) analysis showed that the model including baseline characteristics (age, sex and PC1wbc) along with the nine MPM-related CpGs has a better predictive value for MPM occurrence than the baseline model alone, maintaining some performance also at more than 5 years before diagnosis (area under the curve [AUC] < 5 years = 0.89; AUC 5-10 years = 0.80; AUC >10 years = 0.75; baseline AUC range = 0.63-0.67). DNAm changes as noninvasive biomarkers in prediagnostic blood samples of MPM cases were investigated for the first time. Their application can improve the identification of asbestos-exposed individuals at higher MPM risk to possibly adopt more intensive monitoring for early disease identification.

Malignant Pleural Mesothelioma Interactome with 364 Novel Protein-Protein Interactions

Malignant pleural mesothelioma (MPM) is an aggressive cancer affecting the outer lining of the lung, with a median survival of less than one year. We constructed an 'MPM interactome' with over 300 computationally predicted protein-protein interactions (PPIs) and over 2400 known PPIs of 62 literature-curated genes whose activity affects MPM. Known PPIs of the 62 MPM associated genes were derived from Biological General Repository for Interaction Datasets (BioGRID) and Human Protein Reference Database (HPRD). Novel PPIs were predicted by applying the HiPPIP algorithm, which computes features of protein pairs such as cellular localization, molecular function, biological process membership, genomic location of the gene, and gene expression in microarray experiments, and classifies the pairwise features as interacting or non-interacting based on a random forest model. We validated five novel predicted PPIs experimentally. The interactome is significantly enriched with genes differentially ex-pressed in MPM tumors compared with normal pleura and with other thoracic tumors, genes whose high expression has been correlated with unfavorable prognosis in lung cancer, genes differentially expressed on crocidolite exposure, and exosome-derived proteins identified from malignant mesothelioma cell lines. 28 of the interactors of MPM proteins are targets of 147 U.S. Food and Drug Administration (FDA)-approved drugs. By comparing disease-associated versus drug-induced differential expression profiles, we identified five potentially repurposable drugs, namely cabazitaxel, primaquine, pyrimethamine, trimethoprim and gliclazide. Preclinical studies may be con-ducted in vitro to validate these computational results. Interactome analysis of disease-associated genes is a powerful approach with high translational impact. It shows how MPM-associated genes identified by various high throughput studies are functionally linked, leading to clinically translatable results such as repurposed drugs. The PPIs are made available on a webserver with interactive user interface, visualization and advanced search capabilities.

What can independent research for mesothelioma achieve to treat this orphan disease?

Introduction: Malignant pleural mesothelioma (MPM) is a rare neoplasm with a poor prognosis, as current therapies are ineffective. Despite the increased understanding of the molecular biology of mesothelioma, there is still a lack of drugs that dramatically enhance patient survival. Area Covered: This review discusses recent and complete clinical trials supported by the NIH, other U.S. Federal agencies, universities and organizations found on clinicaltrials.gov. Firstly, chemotherapy-based trials are described, followed by immunotherapy and multitargeted therapy. Then we introduce drug repositioning and the use of drug docking as tools to find new interesting molecules. Finally, we highlight potential molecular pathways that may play a role in mesothelioma biology and therapy. Expert Opinion: Numerous biases are present in the clinical trials due to a restricted number of cases, inappropriate endpoints and inaccurate stratification of patients which delay the finding of a treatment for MPM. The most crucial issue of independent research for MPM is the lack of more substantive funding to translate these findings to the clinical setting. However, this approach is not necessarily scientific given the low mutational load of mesothelioma relative to other cancers, and therefore patients need a more solid rationale to have a good chance of successful treatment.

Decitabine Enhances Vγ9Vδ2 T Cell-Mediated Cytotoxic Effects on Osteosarcoma Cells via the NKG2DL-NKG2D Axis

γδ T cell-based immunotherapy for osteosarcoma (OS) has shown limited success thus far. DNA-demethylating agents not only induce tumor cell death but also have an immunomodulatory function. In this study, we have assessed the potential benefit of combining decitabine (DAC, a DNA demethylation drug) and γδ T cells for OS immunotherapy. DAC increased the expression of natural killer group 2D (NKG2D) ligands (NKG2DLs), including major histocompatibility complex class I-related chains B (MICB) and UL16-binding protein 1 (ULBP1), on the OS cell surface, making the cells more sensitive to recognition and destruction by cytotoxic γδ T cells. The upregulation of MICB and ULBP1 was due to promoter DNA demethylation. Importantly, the killing of OS cells by γδ T cells was partially reversed by blocking the NKG2D receptor, suggesting that the γδ T cell-mediated cytolysis of DAC-pretreated OS cells was mainly dependent on the NKG2D-NKG2DL axis. The in vivo results were consistent with the in vitro results. In summary, DAC could upregulate MICB and ULBP1 expression in OS cells, and combination treatment involving γδ T cell immunotherapy and DAC could be used to enhance the cytotoxic killing of OS cells by γδ T cells.

Drug repurposing in malignant pleural mesothelioma: a breath of fresh air?

Drug repurposing is the use of known drugs for new indications. Malignant pleural mesothelioma (MPM) is a rare cancer with a poor prognosis. So far, few treatments have been approved in this disease. However, its incidence is expected to increase significantly, particularly in developing countries. Consequently, drug repurposing appears as an attractive strategy for drug development in MPM, since the known pharmacology and safety profile based on previous approvals of repurposed drugs allows for faster time-to-market for patients and lower treatment cost. This is critical in low- and middle-income countries where access to expensive drugs is limited. This review assesses the published preclinical and clinical data about drug repurposing in MPM.In this review, we identified 11 therapeutic classes that could be repositioned in mesothelioma. Most of these treatments have been evaluated in vitro, half have been evaluated in vivo in animal models of MPM and only three (i.e. valproate, thalidomide and zoledronic acid) have been investigated in clinical trials, with limited benefits so far. Efforts could be coordinated to pursue further investigations and test promising drugs identified in preclinical experiments in appropriately designed clinical trials.

Inhibitory effects of CP on the growth of human gastric adenocarcinoma BGC-823 tumours in nude mice

Objective

To investigate the potential antitumour effects of [2-(6-amino-purine-9-yl)-1-hydroxy-phosphine acyl ethyl] phosphonic acid (CP) against gastric adenocarcinoma.

Methods

Human BGC-823 xenotransplants were established in nude mice. Animals were randomly divided into control and CP groups, which were administered NaHCO₃ vehicle alone or CP dissolved in NaHCO₃ (200 µg/kg body weight) daily, respectively. Tumour volume was measured weekly for 6 weeks. Resected tumours were assayed for proliferative activity with anti-Ki-67 or anti-proliferating cell nuclear antigen (PCNA) antibodies. Cell apoptosis was examined using terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assays and with caspase-3 immunostaining. Proteins were measured by Western blotting.

Results

There was a significant reduction in tumour volume and a reduced percentage of Ki-67-positive or PCNA-positive cells in the CP group compared with the control group. The percentage of TUNEL-positive or caspase 3-positive cells significantly increased following CP treatment compared with the control group. Tumours from the CP group had higher levels of phosphorylated-extracellular signal-regulated kinase (p-ERK) and phosphorylated-AKT (p-AKT) compared with control tumours.

Conclusion

CP treatment inhibited tumour growth and induced tumour cell apoptosis in a nude mouse model of BGC-823 gastric adenocarcinoma. Activation of the AKT and ERK signalling pathways may mediate this antitumour activity.

Valproic Acid Combined with Zoledronate Enhance γδ T Cell-Mediated Cytotoxicity against Osteosarcoma Cells via the Accumulation of Mevalonate Pathway Intermediates

The long-term survival of osteosarcoma has remained unchanged in the last several decades. Immunotherapy is proved to be a promising therapeutic strategy against osteosarcoma, especially for those with metastasis. Our previous study explored the sensibilization of zoledronate (ZOL) in γδ T cell-mediated cytotoxicity against osteosarcoma, but we have not yet elucidated the specific mechanism. Besides, high concentration is required to achieve these effects, whereas plasma ZOL concentration declines rapidly in the circulation. Valproic acid (VPA), a histone deacetylase inhibitor commonly used as the antiepileptic drug, has attracted much attention due to its synergistic antitumor efficacy with chemotherapy or immunotherapy. Here, we demonstrated that VPA combined with ZOL revealed the synergistic effect in enhancing antitumor efficacy of γδ T cells against osteosarcoma cells. This enhancement was mainly TCR-mediated and largely dependent on granule exocytose pathway. Of note, our findings indicated that ZOL sensitized osteosarcoma cells to γδ T cells by increasing the accumulation of the mevalonate pathway intermediates, which could be facilitated by VPA. We also found that this combination had similar effects on primary osteosarcoma cells. All the results suggested that VPA combined with ZOL could reduce the dose required to achieve a significant antitumor effect of γδ T cells, promoting it to be a novel therapy against osteosarcoma.

Anti-cancer effects of nitrogen-containing bisphosphonates on human cancer cells

Zoledronic acid, a potent nitrogen-containing bisphosphonate (NBP), has been extensively used to limit bone turnover in a various diseases including tumors. Recent clinical studies have demonstrated direct anti-cancer effects of zoledronic acid, in addition to its clinical benefits for skeletal-related events. Here we investigated the effects of 4 clinically available NBPs on human tumor cell proliferation. Our data demonstrate a potent anti-proliferative effect of zoledronic acid against glioblastoma (GBM) cell lines, breast cancer cells and GBM patient-derived lines. Zoledronic acid also effectively inhibited GBM tumor growth in xenograft mouse models. Zoledronic acid strongly stimulated autophagy but not apoptotic signals in all tested cells. Only one intermediate product of cholesterols synthesis pathway, geranylgeranyl diphosphate (GGPP) rescued cells from the cytotoxic effects of zoledronic acid. To further investigate the effect of GGPP, we knocked down RABGGTA, which encodes a subunit of the Rabgeranylgeranyltransferase protein. This knockdown induced an effect similar to zoledronic acid in cancer cell lines. These data are promising and suggested a potential for zoledronic acid as an anti-cancer agent, through its ablation of the function of Rab proteins.

Combination of a third generation bisphosphonate and replication-competent adenoviruses augments the cytotoxicity on mesothelioma

Background

Approximately 80 % of mesothelioma specimens have the wild-type p53 gene, whereas they contain homozygous deletions in the INK4A/ARF locus that encodes p14^ARF and the 16^INK4A genes. Consequently, the majority of mesothelioma is defective of the p53 pathways. We examined whether zoledronic acid (ZOL), a third generation bisphosphonate, and adenoviruses with a deletion of the E1B-55kD gene (Ad-delE1B55), which augments p53 levels in the infected tumors, could produce combinatory anti-tumor effects on human mesothelioma cells bearing the wild-type p53 gene.

Methods

Cytotoxicity of ZOL and Ad-delE1B55 was assessed with a WST assay. Cell cycle changes were tested with flow cytometry. Expression levels of relevant molecules were examined with western blot analysis to investigate a possible mechanism of cytotoxicity. Furthermore, the expressions of Ad receptors on target cells and infectivity were estimated with flow cytometry. Viral replication was assayed with the tissue culture infection dose method.

Results

A combinatory use of ZOL and Ad-delE1B55 suppressed cell growth and increased sub-G1 or S-phase populations compared with a single agent, depending on cells tested. The combinatory treatment up-regulated p53 levels and subsequently enhanced the cleavage of caspase-3, 8, 9 and poly (ADP-ribose) polymerase, but expression of molecules involved in autophagy pathways were inconsistent. ZOL-treated cells also increased Ad infectivity with a dose-dependent manner and augmented Ad replication although the expression levels of integrin molecules, one of the Ad receptors, were down-regulated.

Conclusions

These findings indicated that ZOL and Ad-delE1B55 achieved combinatory anti-tumor effects through augmented apoptotic pathways or increased viral replication.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2483-y) contains supplementary material, which is available to authorized users.

An intrapleural administration of zoledronic acid for inoperable malignant mesothelioma patients: a phase I clinical study protocol

Background

The third generation of bisphosphonates is clinically in use for patients of osteoporosis or malignancy-linked hypercalcemia. The agents can also produce anti-tumor effects on bone metastasis of several types of tumors. We recently found that one of the agents achieved cytotoxicity to mesothelioma in vitro and in an orthotopic animal model. Mesothelioma is resistant to a number of chemotherapeutic agents, and suppression of local tumor growth is beneficial to the patients since metastasis to extra-thoracic organs is relatively infrequent until a late stage.

Methods/design

We demonstrated in an orthotopic mouse model that an intrapleural but not intravenous injection of zoledronic acid, one of the third generation bisphosphonates, at a clinically equivalent dose suppressed the tumor growth. Nevertheless, a high concentration of zoledronic acid administrated in the pleural cavity produced pleural adhesion. We also showed that zoledronic acid produced synergistic cytotoxic effects with cisplatin, the first-line chemotherapeutic agent for mesothelioma. We then planned to conduct a phase I clinical study to investigate any adverse effects and a possible clinical benefits produced by an intrapleural administration of zoledronic acid to mesothelioma patients who became resistant to the first-line chemotherapeutic agents. The clinical trial is a dose escalation study starting with 0.4, 1, 4, 8 and 16 mg per person since safety of administration of zoledronic acid into the pleural cavity remains unknown. Each dose group consists of three persons and the protocol allows to repeat administration of the same dose into the pleural cavity at a 4-weeks interval.

Discussion

We will conduct a possible combinatory study of intrapleural administration of zoledronic acid and systemic administration of the first-line agent to a chemotherapy-naïve patient based on the maximum tolerance dose of zoledronic acid determined by the present clinical trial. We propose that administration of bisphosphonates in a closed cavity is a treatment strategy for tumors developed in the cavity probably through the direct cytotoxic activity.

Trial registration: UMIN clinical trials registry, Japan. Register ID: UMIN8093.

Zoledronic acid induces apoptosis via stimulating the expressions of ERN1, TLR2, and IRF5 genes in glioma cells

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor that affects older people. Although the current therapeutic approaches for GBM include surgical resection, radiotherapy, and chemotherapeutic agent temozolomide, the median survival of patients is 14.6 months because of its aggressiveness. Zoledronic acid (ZA) is a nitrogen-containing bisphosphonate that exhibited anticancer activity in different cancers. The purpose of this study was to assess the potential effect of ZA in distinct signal transduction pathways in U87-MG cells. In this study, experiments performed on U87-MG cell line (Human glioblastoma-astrocytoma, epithelial-like cell line) which is an in vitro model of human glioblastoma cells to examine the cytotoxic and apoptotic effects of ZA. IC50 dose of ZA, 25 μM, applied on U87-MG cells during 72 h. ApoDIRECT In Situ DNA Fragmentation Assay was used to investigate apoptosis of U87MG cells. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) (LightCycler480 System) was carried out for 48 gene expression like NF-κB, Toll-like receptors, cytokines, and inteferons. Our results indicated that ZA (IC50 dose) increased apoptosis 1.27-fold in U87MG cells according to control cells. According to qRT-PCR data, expression levels of the endoplasmic reticulum-nuclei-1 (ERN1), Toll-like receptor 2 (TLR2), and human IFN regulatory factor 5 (IRF5) tumor suppressor genes elevated 2.05-, 2.08-, and 2.3-fold by ZA, respectively, in U87MG cells. Our recent results indicated that ZA have a key role in GBM progression and might be considered as a potential agent in glioma treatment.

Zoledronic acid overcomes chemoresistance and immunosuppression of malignant mesothelioma

The human malignant mesothelioma (HMM) is characterized by a chemoresistant and immunosuppressive phenotype. An effective strategy to restore chemosensitivity and immune reactivity against HMM is lacking. We investigated whether the use of zoledronic acid is an effective chemo-immunosensitizing strategy.

We compared primary HMM samples with non-transformed mesothelial cells.

HMM cells had higher rate of cholesterol and isoprenoid synthesis, constitutive activation of Ras/extracellular signal-regulated kinase1/2 (ERK1/2)/hypoxia inducible factor-1α (HIF-1α) pathway and up-regulation of the drug efflux transporter P-glycoprotein (Pgp). By decreasing the isoprenoid supply, zoledronic acid down-regulated the Ras/ERK1/2/HIF-1α/Pgp axis and chemosensitized the HMM cells to Pgp substrates. The HMM cells also produced higher amounts of kynurenine, decreased the proliferation of T-lymphocytes and expanded the number of T-regulatory (Treg) cells. Kynurenine synthesis was due to the transcription of the indoleamine 1,2 dioxygenase (IDO) enzyme, consequent to the activation of the signal transducer and activator of transcription-3 (STAT3). By reducing the activity of the Ras/ERK1/2/STAT3/IDO axis, zoledronic acid lowered the kyurenine synthesis and the expansion of Treg cells, and increased the proliferation of T-lymphocytes.

Thanks to its ability to decrease Ras/ERK1/2 activity, which is responsible for both Pgp-mediated chemoresistance and IDO-mediated immunosuppression, zoledronic acid is an effective chemo-immunosensitizing agent in HMM cells.

A randomised controlled trial of intravenous zoledronic acid in malignant pleural disease: a proof of principle pilot study

Introduction

Animal studies have shown Zoledronic Acid (ZA) may diminish pleural fluid accumulation and tumour bulk in malignant pleural disease (MPD). We performed a pilot study to evaluate its effects in humans.

Methods

We undertook a single centre, double-blind, placebo-controlled trial in adults with MPD. Patients were randomised (1:1) to receive 2 doses of intravenous ZA or placebo, 3 weeks apart and were followed-up for 6 weeks. The co-primary outcomes were change in Visual Analogue Scale (VAS) score measured breathlessness during trial follow-up and change in the initial area under the curve (iAUC) on thoracic Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) from randomisation to week 5. Multiple secondary endpoints were also evaluated.

Results

Between January 2010 and May 2013, 30 patients were enrolled, 24 randomised and 4 withdrew after randomisation (1 withdrew consent; 3 had a clinical decline). At baseline, the ZA group were more breathless, had more advanced disease on radiology and worse quality of life than the placebo group. There was no significant difference between the groups with regards change in breathlessness (Adjusted mean difference (AMD) 4.16 (95%CI −4.7 to 13.0)) or change in DCE-MRI iAUC (AMD −15.4 (95%CI −58.1 to 27.3). Two of nine (22%) in the ZA arm had a >10% improvement by modified RECIST (vs 0/11 who received placebo). There was no significant difference in quality of life measured by the QLQ-C30 score (global QOL: AMD -4.1 (-13.0 to 4.9)), side effects or serious adverse event rates.

Conclusions

This is the first human study to evaluate ZA in MPD. The study is limited by small numbers and imbalanced baseline characteristics. Although no convincing treatment effect was identified, potential benefits for specific subgroups of patients cannot be excluded. This study provides important information regarding the feasibility of future trials to evaluate the effects of ZA further.

Trial Registration

UK Clinical Research Network ID 8877 ISRCTN17030426www.isrctn.com

Zoledronic acid induces apoptosis and S-phase arrest in mesothelioma through inhibiting Rab family proteins and topoisomerase II actions

Zoledronic acid (ZOL), a nitrogen-containing bisphosphonate, produced anti-tumor effects through apoptosis induction or S-phase arrest depending on human mesothelioma cells tested. An addition of isoprenoid, geranylgeraniol but not farnesol, negated these ZOL-induced effects, indicating that the ZOL-mediated effects were attributable to depletion of geranylgeranyl pyrophosphates which were substrates for prenylation processes of small guanine-nucleotide-binding regulatory proteins (small G proteins). ZOL-treated cells decreased a ratio of membrane to cytoplasmic fractions in RhoA, Cdc42 and Rab6 but less significantly Rac1 proteins, indicating that these proteins were possible targets for ZOL-induced actions. We further analyzed which small G proteins were responsible for the three ZOL-induced effects, caspase-mediated apoptosis, S-phase arrest and morphological changes, using inhibitors for respective small G proteins and siRNA for Cdc42. ZOL-induced apoptosis is due to insufficient prenylation of Rab proteins because an inhibitor of geranlygeranyl transferase II that was specific for Rab family proteins prenylation, but not others inhibitors, activated the same apoptotic pathways that ZOL did. ZOL suppressed an endogenous topoisomerase II activity, which was associated with apoptosis and S-phase arrest in respective cells because we detected the same cell cycle changes in etoposide-treated cells. Inhibitors for geranlygeranyl transferase I and for RhoA produced morphological changes and disrupted actin fiber structures, both of which were similar to those by ZOL treatments. These data demonstrated that anti-tumor effects by ZOL were attributable to inhibited functions of respective small G proteins and topoisomerase II activity, and suggested that cellular factors were involved in the differential cell cycle changes.

Bone markers for monitoring efficacy in patients with bone metastases receiving zoledronic acid: a review of published data

Bone metastases occur frequently in patients with advanced solid tumors and can create serious clinical problems that are commonly referred to as skeletal-related events. Although bisphosphonates, especially zoledronic acid, have emerged as an integral determinant of managing metastatic bone disease, their application remains a challenge because of the lack of standardized measures and their side effects. Since factors derived from bone metabolism are potentially useful to measure the efficacy of zoledronic acid, several clinical trials have investigated these bone markers with respect to their monitoring values. The results suggest that a greater decline in bone marker levels is associated with a more reduced incidence of skeletal-related events and a better improvement of symptoms. This review summarizes the available evidence on the clinical use of bone markers in monitoring zoledronic acid in various cancers with bone metastases including breast, prostate and lung cancer.

Zoledronic acid reverses the epithelial-mesenchymal transition and inhibits self-renewal of breast cancer cells through inactivation of NF-κB

Zoledronic acid, a third-generation bisphosphonate, has been shown to reduce cell migration, invasion, and metastasis. However, the effects of zoledronic acid on the epithelial-mesenchymal transition (EMT), a cellular process essential to the metastatic cascade, remain unclear. Therefore, the effects of zoledronic acid on EMT, using triple-negative breast cancer (TNBC) cells as a model system, were examined in more detail. Zoledronic acid treatment decreased the expression of mesenchymal markers, N-cadherin, Twist, and Snail, and subsequently upregulated expression of E-cadherin. Zoledronic acid also inhibited cell viability, induced cell-cycle arrest, and decreased the proliferative capacity of TNBC, suggesting that zoledronic acid inhibits viability through reduction of cell proliferation. As EMT has been linked to acquisition of a self-renewal phenotype, the effects of zoledronic acid on self-renewal in TNBC were also studied. Treatment with zoledronic acid decreased expression of self-renewal proteins, BMI-1 and Oct-4, and both prevented and eliminated mammosphere formation. To understand the mechanism of these results, the effect of zoledronic acid on established EMT regulator NF-κB was investigated. Zoledronic acid inhibited phosphorylation of RelA, the active subunit of NF-κB, at serine 536 and modulated RelA subcellular localization. Treatment with zoledronic acid reduced RelA binding to the Twist promoter, providing a direct link between inactivation of NF-κB signaling and loss of EMT transcription factor gene expression. Binding of Twist to the BMI-1 promoter was also decreased, correlating modulation of EMT to decreased self-renewal. On the basis of these results, it is proposed that through inactivation of NF-κB, zoledronic acid reverses EMT, which leads to a decrease in self-renewal.