Taurolidine and oxidative stress: a rationale for local treatment of mesothelioma

Common alterations in plasma free amino acid profiles and gut microbiota-derived tryptophan metabolites of five types of cancer patients

Amino acids not only play a vital role in the synthesis of biological molecules such as proteins in cancer malignant cells, they are also essential metabolites for immune cell activation and antitumor effects in the tumor microenvironment. The abnormal changes in amino acid metabolism are closely related to the occurrence and development of tumors and immunity. Intestinal microorganisms play an essential role in amino acid metabolism, and tryptophan and its intestinal microbial metabolites are typical representatives. However, it is known that the cyclic amino acid profile is affected by specific cancer types, so relevant studies mainly focus on one type of cancer and rarely study different cancer forms at the same time. The objective of this study was to examine the PFAA profile of five cancer patients and the characteristics of tryptophan intestinal microbial metabolites to determine whether there are general amino acid changes across tumors. Plasma samples were collected from esophageal (n = 53), lung (n = 73), colorectal (n = 94), gastric (n = 55), breast cancer (n = 25), and healthy control (HC) (n = 139) subjects. PFAA profile and tryptophan metabolites were measured, and their perioperative changes were examined using high-performance liquid chromatography. Univariate analysis revealed significant differences between cancer patients and HC. Furthermore, multivariate analysis discriminated cancer patients from HC. Regression diagnosis models were established for each cancer group using differential amino acids from univariate analysis. Receiver-operating characteristic analysis was applied to evaluate these diagnosis models. Finally, GABA, arginine, tryptophan, taurine, glutamic acid, and melatonin showed common alterations across all types of cancer patients. Metabolic pathway analysis shows that the most significant enrichment pathways were tryptophan, arginine, and proline metabolism. This study provides evidence that common alterations of the metabolites mentioned above suggest their role in the pathogenesis of each cancer patient. It was suggested that multivariate models based on PFAA profiles and tryptophan metabolites might be applicable in the screening of cancer patients.

Allyl Isothiocyanate in the Volatiles of Brassica juncea Inhibits the Growth of Root Rot Pathogens of Panax notoginseng by Inducing the Accumulation of ROS

The cultivation of Panax notoginseng is often seriously hindered by root rot disease caused by the accumulation of soil-borne pathogens. Here, the inhibitory activity of Brassica juncea volatiles on P. notoginseng root rot pathogens was assessed and compounds in volatiles were identified. Furthermore, the antimicrobial activity and mechanism of allyl isothiocyanate (AITC) were deciphered by integrated transcriptome and metabolome analyses. The volatiles of B. juncea showed dose-dependent antimicrobial activity against root rot pathogens. AITC, identified as the main volatile compound, not only significantly inhibited pathogen growth in vitro but also suppressed root rot disease in the field. Integrated transcriptomic and metabolomics analysis revealed that AITC inhibited Fusarium solani by interfering with energy production and induced the accumulation of ROS by decreasing the content of glutathione (GSH). In summary, B. juncea releases AITC to inhibit soil-borne pathogens and could be used as a rotation crop or soil fumigant to alleviate root rot disease.

Does taurolidine have any effect on liver regeneration and oxidation in the experimental hepatectomy model?

Objective: Taurolidine is a bicyclic molecule produced by the natural amino acid taurine. Antibacterial, antiendotoxic and cytoprotective effects of taurolidine have been shown experimentally. Data on the effects of taurolidine on oxidative stress and hepatic regeneration are limited. The aim of the study was to evaluate the effect of taurolidine on hepatic regeneration and oxidative stress in rats undergoing partial hepatectomy.

Material and Methods: Forty adult, male Wistar Albino rats were randomly divided into four equal groups: sham (S) group (n= 10), post-sham opera- tion taurolidine administered (ST) group (n= 10), partial hepatectomy (H) group (n= 10) and post-partial hepatectomy taurolidine administered (HT) group (n= 10). 100 mg/kg/day taurolidine was administered for seven days. Blood and liver tissue samples were collected on postoperative day seven. Liver tissue malondialdehyde, glutathione and Cu-Zn superoxide dismutase activity (SOD) were measured to assess oxidative stress. Binuclear hepato- cyte and Ki-67 antigen levels were measured to evaluate hepatic regeneration.

Results: There was no difference between the groups for malondialdehyde, Cu-Zn superoxide dismutase and glutathione levels (p> 0.05). Binuclear nuclei levels were comparable between the H and HT groups (p= 0.06), while taurolidine decreased binuclear hepatocyte levels in the sham operated groups (p= 0.02). Taurolidine application decreased Ki-67 levels after partial hepatectomy (p= 0.001).

Conclusion: Taurolidine may cause anti-regenerative effects after partial hepatectomy without causing oxidative damage.

Protein Phosphatase 2A as a Drug Target in the Treatment of Cancer and Alzheimer's Disease

Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase which participates in the regulation of multiple cellular processes. As a confirmed tumor suppressor, PP2A activity is downregulated in tumors and its re-activation can induce apoptosis of cancer cells. In the brains of Alzheimer's disease (AD) patients, decreased PP2A activity also plays a key role in promoting tau hyperphosphorylation and Aβ generation. In this review, we discussed compounds aiming at modulating PP2A activity in the treatment of cancer or AD. The upstream factors that inactivate PP2A in diseases have not been fully elucidated and further studies are needed. It will help for the refinement and development of novel and clinically tractable PP2A-targeted compounds or therapies for the treatment of tumor and AD.

Dual functionality of the antimicrobial agent taurolidine which demonstrates effective anti-tumor properties in pediatric neuroblastoma

High-risk, relapsed and refractory neuroblastoma are associated with poor 5-years survival rates, demonstrating the need for investigational therapeutic agents to treat this disease. Taurolidine is derived from the aminosulfoacid taurine and has known anti-microbial and anti-inflammatory properties. Taurolidine has also demonstrated anti-neoplastic effects in a range of cancers, providing the rationale to investigate the activity of taurolidine against neuroblastoma in preclinical studies. We investigated the in vitro activity of taurolidine against neuroblastoma using the alamar blue cytotoxicity assay, phase-contrast light microscopy, western blotting and analysis of global gene expression by RNA-Seq. In vivo activity of taurolidine was evaluated using mouse xenograft models. In vitro pre-clinical data show that taurolidine is cytotoxic to neuroblastoma cell lines, inducing cell death by apoptosis. Analysis of global gene expression and determination of signaling pathway activation scores using the in silico Pathway Activation Network Decomposition Analysis (iPANDA) platform indicates that taurolidine has an effect on the Notch, mitogen-activated protein kinase (MAPK) and interleukin-10 (IL-10) signaling pathways. In vivo experiments in xenograft mouse models show that taurolidine decreases tumor growth and improves survival. These results provide supportive pre-clinical data on the activity of taurolidine against neuroblastoma. The findings support the rationale for further evaluation of taurolidine for the treatment of relapsed/refractory neuroblastoma patients in an early phase clinical trial.

Short-term treatment with taurolidine is associated with liver injury

BACKGROUND

Taurolidine has been used for peritonitis, oncological and catheter-lock treatment because of its anti-inflammatory properties. It has been suggested that taurolidine has no severe side-effects, but after long-term use morphological and functional changes of the liver were reported. The aim of this study was to investigate the effect of short-term use of taurolidine on the liver.

METHODS

In HepaRG cell cultures and on a novel liver biochip dose-dependent effects of taurolidine treatment on hepatocyte adherence and cell viability was investigated. Furthermore, liver enzymes and interleukin- (IL-) 6 were measured in supernatants. Male rats were treated with low- or high-dose taurolidine, respectively, and compared to controls with physiological saline solution administration regarding blood serum parameters and histology.

RESULTS

In HepaRG cell cultures, hepatocyte adherence was significantly decreased, cell death and cleaved caspase-3 were significantly increased after administration of taurolidine in a dose-dependent manner. High-dose application of taurolidine led to elevated liver enzymes and IL-6 secretion in hepatic organoid. After 24 h a significant increase of serum GLDH and ASAT was observed in rats treated with high-dose taurolidine treatment.

CONCLUSIONS

Our results suggest that taurolidine caused liver injury after short-term use in in vitro and in vivo models probably due to direct toxic effects on hepatocytes. Therefore, the taurolidine dose should be titrated in further investigations regarding liver injury and inflammation.

Innovative substance 2250 as a highly promising anti-neoplastic agent in malignant pancreatic carcinoma - in vitro and in vivo

BACKGROUND

Former studies already revealed the anti-neoplastic properties of the anti-infective agent Taurolidine (TRD) against many tumor species in vitro and in vivo. Its anti-proliferative and cell death inducing capacity is largely due to its main derivative Taurultam (TRLT). In this study it could be demonstrated, that substance 2250 - a newly defined innovative structural analogue of TRLT - exhibits an anti-neoplastic effect on malignant pancreatic carcinoma in vitro and in vivo.

METHODS

The anti-neoplastic potential of substance 2250 as well as its mode of action was demonstrated in extensive in vitro analysis, followed by successful and effective in vivo testings, using xenograft models derived from established pancreatic cancer cell lines as well as patient derived tissue.

RESULTS

Our functional analysis regarding the role of oxidative stress (ROS) and caspase activated apoptosis showed, that ROS driven programmed cell death (PCD) is the major mechanisms induced by substance 2250 in pancreatic carcinoma. What is strongly relevant towards clinical practice is especially the observed inhibition of patient derived pancreatic cancer tumor growth in mice treated with this new substance in combination with its sharply higher metabolic stability.

CONCLUSION

These encouraging results provide new therapeutical opportunities in pancreatic cancer treatment and build the basis for further functional analysis as well as first clinical studies for this promising agent.

FTY720 inhibits mesothelioma growth in vitro and in a syngeneic mouse model

BACKGROUND

Malignant mesothelioma (MM) is a very aggressive type of cancer, with a dismal prognosis and inherent resistance to chemotherapeutics. Development and evaluation of new therapeutic approaches is highly needed. Immunosuppressant FTY720, approved for multiple sclerosis treatment, has recently raised attention for its anti-tumor activity in a variety of cancers. However, its therapeutic potential in MM has not been evaluated yet.

METHODS

Cell viability and anchorage-independent growth were evaluated in a panel of MM cell lines and human mesothelial cells (HM) upon FTY720 treatment to assess in vitro anti-tumor efficacy. The mechanism of action of FTY720 in MM was assessed by measuring the activity of phosphatase protein 2A (PP2A)-a major target of FTY720. The binding of the endogenous inhibitor SET to PP2A in presence of FTY720 was evaluated by immunoblotting and immunoprecipitation. Signaling and activation of programmed cell death were evaluated by immunoblotting and flow cytometry. A syngeneic mouse model was used to evaluate anti-tumor efficacy and toxicity profile of FTY720 in vivo.

RESULTS

We show that FTY720 significantly suppressed MM cell viability and anchorage-independent growth without affecting normal HM cells. FTY720 inhibited the phosphatase activity of PP2A by displacement of SET protein, which appeared overexpressed in MM, as compared to HM cells. FTY720 promoted AKT dephosphorylation and Bcl-2 degradation, leading to induction of programmed cell death, as demonstrated by caspase-3 and PARP activation, as well as by cytochrome c and AIF intracellular translocation. Moreover, FTY720 administration in vivo effectively reduced tumor burden in mice without apparent toxicity.

CONCLUSIONS

Our preclinical data indicate that FTY720 is a potentially promising therapeutic agent for MM treatment.

Cisplatin in combination with Phenethyl Isothiocyanate (PEITC), a potential new therapeutic strategy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a very aggressive form of cancer with a poor diagnosis and prognosis. The first line treatment for MPM is a combination of cisplatin and Pemetrexed, which displayed limited efficacy and severe side effects. The naturally occurring compound phenethyl isothiocyanate (PEITC) previously showed interesting anti-tumor properties on several cancer cell lines. We thus aim at evaluating PEITC used alone or in combination with cisplatin in order to improve MPM treatment.

Nine MPM cell lines and primary mesothelial cells (PMC), co-cultured or not with M2 macrophages present in MPM microenvironment, were used to assess PEITC and cisplatin anti-tumor properties. Compounds were used alone or in combination.

Both PEITC and cisplatin were cytotoxic on MPM cells in a dose dependent manner. We herein showed that PEITC-induced cytotoxicity was due to the generation of reactive oxygen species. Moreover, we showed that cisplatin-PEITC combination allowed the potentialization of both compounds' cytotoxic effects and prevented the emergence of resistant MPM cells. Interestingly, PMC were not sensitive to the combination. Finally, we showed that M2 macrophages did not alter the anti-tumor properties of the combination. Cisplatin-PEITC combination thus represents a promising strategy to induce a selective toxicity towards malignant cells.

Redox-directed cancer therapeutics: Taurolidine and Piperlongumine as broadly effective antineoplastic agents (review)

Targeting the oxygen stress response pathway is considered a promising strategy to exert antineoplastic activity in a broad spectrum of tumor types. Supporting this view, we summarize the mechanism of action of Taurolidine and Piperlongumine, two antineoplastic agents with strikingly broad tumor selectivity. Taurolidine enhances the oxidative stress (ROS) selectively in tumor cells. Its cytotoxicity for various tumor cells in vitro and in vivo, which includes tumor stem cells, is based on the induction of programmed cell death, largely via apoptosis but also necroptosis and autophagy. The redox-directed mechanism of action of Taurolidine is apparent from the finding that reducing agents e.g., N-acetylcysteine or glutathione impair its cytotoxicity, while its effectiveness is enhanced by agents which inhibit the cellular anti‑oxidant capacity. A similar redox-directed antineoplastic action is shown by Piperlongumine, a recently described experimental drug of plant origin. Taurolidine is particularly advantageous in surgical oncology as this taurine-derivative can be applied perioperatively or systemically with good tolerability as shown in initial clinical applications.

Structure, regulation, and pharmacological modulation of PP2A phosphatases

Protein phosphatases of the type 2A family (PP2A) represent a major fraction of cellular Ser/Thr phosphatase activity in any given human tissue. In this review, we describe how the holoenzymic nature of PP2A and the existence of several distinct PP2A composing subunits allow for the generation of multiple structurally and functionally different PP2A complexes, explaining why PP2A is involved in the regulation of so many diverse cell biological and physiological processes. Moreover, in human disease, most notably in several cancers and Alzheimer's Disease, PP2A expression and/or activity have been found significantly decreased, underscoring its important functions as a major tumor suppressor and tau phosphatase. Hence, several recent preclinical studies have demonstrated that pharmacological restoration of PP2A activity, as well as pharmacological PP2A inhibition, under certain conditions, may be of significant future therapeutic value.

In vitro screening of synergistic ascorbate-drug combinations for the treatment of malignant mesothelioma

Malignant mesothelioma (MMe) is a lethal tumor arising from the mesothelium of serous cavities as a result of exposure to asbestos. Current clinical standards consist of combined treatments, but an effective therapy has not been established yet and there is an urgent need for new curative approaches. Ascorbate is a nutrient that is also known as a remedy in the treatment of cancer. In the present study, we have tested the cytotoxicity of ascorbate to MMe cells in combination with drugs used in MMe therapy, such as cisplatin, etoposide, gemcitabine, imatinib, paclitaxel, and raltitrexed, as well as with promising antitumor compounds like taurolidine, α-tocopherol succinate, and epigallocatechin-3-gallate (EGCG). Dose-response curves obtained for each compound by applying the neutral red uptake (NRU) assay to MMe cells growing in vitro, allowed to obtain IC50 values for each compound used singularly. Thereafter, NRU data obtained from each ascorbate/drug combination were analyzed through Tallarida's isobolograms at the IC50 level (Tallarida, 2000), revealing synergistic interactions for ascorbate/gemcitabine and ascorbate/EGCG. These results were further confirmed through comparisons between theoretical additivity IC50 and observed IC50 from fixed-ratio dose-response curves, and over a broad range of IC levels, by using Chou and Talalay's combination index (Chou and Talalay, 1984). Synergistic interactions were also shown by examining apoptosis and necrosis rates, using the caspase 3 and lactic dehydrogenase assays, respectively. Hence, data indicate that ascorbate/gemcitabine and ascorbate/EGCG affect synergistically the viability of MMe cells and suggest their possible use in the clinical treatment of this problematic cancer.

Phosphoprotein phosphatase 2A: a novel druggable target for Alzheimer's disease

Tau hyperphosphorylation is thought to play an important role in the etiology of Alzheimer's disease by facilitating the formation of neurofibrillary tangles. Reducing phosphorylation through kinase inhibition has therefore emerged as a target for drug development, but despite considerable efforts to develop therapeutic kinase inhibitors, success has been limited. An alternative approach is to develop pharmaceuticals to enhance the activity of the principal phospho-tau phosphatase, phosphoprotein phosphatase 2A (PP2A). In this article we review evidence that this mechanism is pharmacologically achievable and has promise for delivering the next generation of Alzheimer's disease therapeutics. A number of different chemotypes have been reported to lead to enhanced PP2A activity through a range of proposed mechanisms. Some of these compounds appear to act directly as allosteric activators of PP2A, while others act indirectly by inhibiting the binding of PP2A inhibitors or by altering post-translational modifications that act in turn to regulate PP2A activity towards phospho-tau. These results indicate that PP2A may provide a useful target that can be safely, selectively and effectively modulated through pharmaceutical intervention to treat Alzheimer's disease.

Role of mutagenicity in asbestos fiber-induced carcinogenicity and other diseases

The cellular and molecular mechanisms of how asbestos fibers induce cancers and other diseases are not well understood. Both serpentine and amphibole asbestos fibers have been shown to induce oxidative stress, inflammatory responses, cellular toxicity and tissue injuries, genetic changes, and epigenetic alterations in target cells in vitro and tissues in vivo. Most of these mechanisms are believe to be shared by both fiber-induced cancers and noncancerous diseases. This article summarizes the findings from existing literature with a focus on genetic changes, specifically, mutagenicity of asbestos fibers. Thus far, experimental evidence suggesting the involvement of mutagenesis in asbestos carcinogenicity is more convincing than asbestos-induced fibrotic diseases. The potential contributions of mutagenicity to asbestos-induced diseases, with an emphasis on carcinogenicity, are reviewed from five aspects: (1) whether there is a mutagenic mode of action (MOA) in fiber-induced carcinogenesis; (2) mutagenicity/carcinogenicity at low dose; (3) biological activities that contribute to mutagenicity and impact of target tissue/cell type; (4) health endpoints with or without mutagenicity as a key event; and finally, (5) determinant factors of toxicity in mutagenicity. At the end of this review, a consensus statement of what is known, what is believed to be factual but requires confirmation, and existing data gaps, as well as future research needs and directions, is provided.

Gene expression analysis of cell death induction by taurolidine in different malignant cell lines

Background

The anti-infective agent Taurolidine (TRD) has been shown to have cell death inducing properties, but the mechanism of its action is largely unknown. The aim of this study was to identify potential common target genes modulated at the transcriptional level following TRD treatment in tumour cell lines originating from different cancer types.

Methods

Five different malignant cell lines (HT29, Chang Liver, HT1080, AsPC-1 and BxPC-3) were incubated with TRD (100 μM, 250 μM and 1000 μM). Proliferation after 8 h and cell viability after 24 h were analyzed by BrdU assay and FACS analysis, respectively. Gene expression analyses were carried out using the Agilent -microarray platform to indentify genes which displayed conjoint regulation following the addition of TRD in all cell lines. Candidate genes were subjected to Ingenuity Pathways Analysis and selected genes were validated by qRT-PCR and Western Blot.

Results

TRD 250 μM caused a significant inhibition of proliferation as well as apoptotic cell death in all cell lines. Among cell death associated genes with the strongest regulation in gene expression, we identified pro-apoptotic transcription factors (EGR1, ATF3) as well as genes involved in the ER stress response (PPP1R15A), in ubiquitination (TRAF6) and mitochondrial apoptotic pathways (PMAIP1).

Conclusions

This is the first conjoint analysis of potential target genes of TRD which was performed simultaneously in different malignant cell lines. The results indicate that TRD might be involved in different signal transduction pathways leading to apoptosis.

Comparative analysis of cell death induction by Taurolidine in different malignant human cancer cell lines

Background

Taurolidine (TRD) represents an anti-infective substance with anti-neoplastic activity in many malignant cell lines. So far, the knowledge about the cell death inducing mechanisms and pathways activated by TRD is limited. The aim of this study was therefore, to perform a comparative analysis of cell death induction by TRD simultaneously in different malignant cell lines.

Materials and methods

Five different malignant cell lines (HT29/Colon, Chang Liver/Liver, HT1080/fibrosarcoma, AsPC-1/pancreas and BxPC-3/pancreas) were incubated with increasing concentrations of TRD (100 μM, 250 μM and 1000 μM) for 6 h and 24 h. Cell viability, apoptosis and necrosis were analyzed by FACS analysis (Propidiumiodide/AnnexinV staining). Additionally, cells were co-incubated with the caspase Inhibitor z-VAD, the radical scavenger N-Acetylcystein (NAC) and the Gluthation depleting agent BSO to examine the contribution of caspase activation and reactive oxygen species in TRD induced cell death.

Results

All cell lines were susceptible to TRD induced cell death without resistance toward this anti-neoplastic agent. However, the dose response effects were varying largely between different cell lines. The effect of NAC and BSO co-treatment were highly different among cell lines - suggesting a cell line specific involvement of ROS in TRD induced cell death. Furthermore, impact of z-VAD mediated inhibition of caspases was differing strongly among the cell lines.

Conclusion

This is the first study providing a simultaneous evaluation of the anti-neoplastic action of TRD across several malignant cell lines. The involvement of ROS and caspase activation was highly variable among the five cell lines, although all were susceptible to TRD induced cell death. Our results indicate, that TRD is likely to provide multifaceted cell death mechanisms leading to a cell line specific diversity.