Digital smoking cessation with a comprehensive guideline-based app - results of a nationwide, multicentric, parallel, randomized controlled trial in Germany.

BACKGROUND: Smoking tobacco implies significant health hazards. Digital cessation support can get more smokers in contact with guideline-based cessation. The objective was to test the efficacy of a guideline-based smoking cessation app (NichtraucherHelden®). The hypothesis was a significant higher cessation rate in the intervention group. METHODS: The study was a nationwide, multicentric, prospective, parallel, randomized controlled trial in Germany from November 2021 to March 2023. Recruitment took place in medical practices and by telephone via study centres. Eligible participants were adult tobacco-dependent smokers according to ICD-10 (F17.2). Randomization (1:1) was operated by a computer-generated stratified 1:1 block procedure. Intervention (IG; n = 336) and control group (CG; n = 325) were briefly advised with regard to stop smoking, IG was additionally treated with the cessation app. Primary endpoint was the self-reported 7-day-point-abstinence after 6 months with an intention to treat analysis. Secondary endpoints comprised prolonged abstinence and biochemically verified abstinence. The study was registered at the German Registry of Clinical Trials (DRKS00025933, UTN U1111-1268-2181) and was approved by the competent ethic committees (leading ethic committee Berlin #Eth-52/20). RESULTS: 336 participants (IG) and 325 (CG) were analysed. Seven-day point prevalence was significantly higher in the app group (IG) (20% vs. 10%, OR 2.2 (1.4 - 3.4)). Additionally, the prolonged abstinence and the objective abstinence rate were significantly higher in the app group. CONCLUSIONS: The NichtraucherHelden App doubles the abstinence rate. Apps can bridge the gap between the small numbers of therapeutic offers and the need for modern evidence-based cessation support. IMPLICATIONS: The study is the first to provide evidence for the feasibility and efficacy of guideline-based digital smoking cessation provided by a smartphone app for the German statutory health insurance system (SHI). Smoking cessation support by smartphone apps could be broadly distributed and thus bring more smokers in contact with guideline-based cessation support than to date and increase the number of successful quitters substantially.

Preclinical Efficacy and Toxicity Analysis of the Pan-Histone Deacetylase Inhibitor Gossypol for the Therapy of Colorectal Cancer or Hepatocellular Carcinoma.

Gossypol, a sesquiterpenoid found in cotton seeds, exerts anticancer effects on several tumor entities due to inhibition of DNA synthesis and other mechanisms. In clinical oncology, histone deacetylase inhibitors (HDACi) are applied as anticancer compounds. In this study, we examined whether gossypol harbors HDAC inhibiting activity. In vitro analyses showed that gossypol inhibited class I, II, and IV HDAC, displaying the capability to laterally interact with the respective catalytic center and is, therefore, classified as a pan-HDAC inhibitor. Next, we studied the effects of gossypol on human-derived hepatoma (HepG2) and colon carcinoma (HCT-116) cell lines and found that gossypol induced hyperacetylation of histone protein H3 and/or tubulin within 6 h. Furthermore, incubation with different concentrations of gossypol (5-50 µM) over a time period of 96 h led to a prominent reduction in cellular viability and proliferation of hepatoma (HepG2, Hep3B) and colon carcinoma (HCT-116, HT-29) cells. In-depth analysis of underlying mechanisms showed that gossypol induced apoptosis via caspase activation. For pre-clinical evaluation, toxicity analyses showed toxic effects of gossypol in vitro toward non-malignant primary hepatocytes (PHH), the colon-derived fibroblast cell line CCD-18Co, and the intestinal epithelial cell line CCD 841 CoN at concentrations of ≥5 µM, and embryotoxicity in chicken embryos at ≥2.5 µM. In conclusion, the pronounced inhibitory capacity of gossypol on cancer cells was characterized, and pan-HDACi activity was detected in silico, in vitro, by inhibiting individual HDAC isoenzymes, and on protein level by determining histone acetylation. However, for clinical application, further chemical optimization is required to decrease cellular toxicity.

Efficacy of the OTSC System in the treatment of GI bleeding and wall defects: a PMCF meta-analysis.

Since its market launch in 2007, the endoscopic OTSC clipping system has been the object of intensive clinical research. These data were systematically collected for post-market clinical follow-up (PMCF). The aim of the study was the systematic review of the efficacy and safety of the OTSC System. The PMCF database was systematically searched for clinical data on OTSC therapy of GI hemorrhage (H), acute leaks/perforations (AL) and chronic leaks/fistulae (CL). Major outcomes were successful clip application and durable hemostasis/closure of defects. Comprehensive pooled success proportions were established by meta-analytical methods. Four-hundred-fifty-seven publications were reviewed. Fifty-eight articles comprising 1868 patients fulfilled criteria to be included in the analysis. These consisted of retrospective analyses, prospective observational trials, one randomized-controlled trial (STING) and one quasi-controlled study (FLETRock). The pooled proportion analysis revealed high overall proportions of technical success: H - mean 93.0% [95%CI 90.2-95.4], AL-mean 89.7% [95%CI 85.9-92.9] and CL-mean 83.8% [95%CI 76.9-89.7]. Pooled durable clinical success proportions were: H-mean 87.5% [95%CI 80.5-93.2], AL-mean 81.4% [95%CI 77.0-85.3] and CL-mean 63.0% [95%CI 53.0-72.3]. By pooling all clinical data gained, we conclude that OTSC application in GI hemorrhage and closure of GI lesions is safe and effective in real clinical use.

Ontology-based specification and generation of search queries for post-market surveillance.

BACKGROUND: The vigilant observation of medical devices during post-market surveillance (PMS) for identifying safety-relevant incidents is a non-trivial task. A wide range of sources has to be monitored in order to integrate all accessible data about the safety and performance of a medical device. PMS needs to be supported by an efficient search strategy and the possibility to create complex search queries by domain experts. RESULTS: We use ontologies to support the specification of search queries and the preparation of the document corpus, which contains all relevant documents. In this paper, we present (1) the Search Ontology (SON) v2.0, (2) an Excel template for specifying search queries, and (3) the Search Ontology Generator (SONG), which generates complex queries out of the Excel template. Based on our approach, a service-oriented architecture was designed, which supports and assists domain experts during PMS. Comprehensive testing confirmed the correct execution of all SONG functions. The applicability of our method and of the developed tools was evaluated by domain experts. The test persons concordantly rated our solution after a short period of training as highly user-friendly, intuitive and well applicable for supporting PMS. CONCLUSIONS: The Search Ontology is a promising domain-independent approach to specify complex search queries. Our solution allows advanced searches for relevant documents in different domains using suitable domain ontologies.

Preclinical evaluation of a novel thermally sensitive co-polymer (LiftUp) for endoscopic resection.

Introduction: Endoscopic resection techniques can successfully resect large lesions either in "en bloc" fashion or in "piece-meal" technique by using a submucosal injection solution. The aim of this study was to evaluate the safety of a novel injectable, containing thermally sensitive co-polymer from ethylenoxide and propylenoxide (LiftUp) used as submucosal injection solution.Material and methods: We conducted an in vivo animal trial in the porcine model to evaluate the LiftUp gel in a preclinical setting and to study the effectiveness of mucosal lifting and the safety of the new injectable. In seven animals a total of 63 injections and endoscopic resections were carried out in different anatomical locations (esophagus, stomach and rectum). The resection sites were controlled endoscopically one and four weeks after resection and a histopathological evaluation of the resection sites was performed after four weeks.Results: The application of LiftUp was safe and there were no negative effects on wound healing after injection and resection. A major procedural complication rate (defined as perforation and major haemorrhage) of 3.2% was registered, which undercuts the anticipated mean complication rate of 4-8%. Furthermore, there was no necessity of reinjection after the initial submucosal injection in 90.5% and no procedural complications in 98.8%. The histopathological examination of the tissue samples indicated normal wound healing with granulation tissue and epithelialisation.Conclusion: The use of LiftUp as submucosal injection solution was feasible for different endoscopic resection techniques, with high and long-lasting elevation and fewer procedural adverse events than expected at trial planning. The new injectable is a practical advancement over the current state-of-the-art of submucosal injection and could fasten up the resection procedure and make endoscopic 'en bloc' resection safer.

Enhanced killing of therapy-induced senescent tumor cells by oncolytic measles vaccine viruses.

Therapy-induced senescence (TIS) as a permanent growth arrest can be induced by various stimuli, including anticancer compounds. TIS emerged as a promising strategy to overcome resistance phenomena. However, senescent cancer cells might regain proliferation activity in vivo or even secrete tumor-promoting cytokines. Therefore, successful exploitation of TIS in cancer treatment simultaneously requires the development of effective strategies to eliminate senescent cancer cells. Virotherapy aims to selectively hit tumor cells, thus a combination with senescence-inducing drugs was explored. As a model, we chose measles vaccine virus (MeV), which does not interfere with cellular senescence by itself. In different tumor cell types, such as hepatoma, pancreatic and mammary gland carcinoma, we demonstrate efficient viral replication and lysis after TIS by gemcitabine, doxorubicin or taxol. Applying real time imaging, we even found an accelerated lysis of senescent cancer cells, supporting an enhanced viral replication with an increase in cell-associated and released infectious MeV particles. In summary, we show as a proof-of-concept that senescent tumor cells can be efficiently exploited as virus host cells by oncolytic MeV. These observations open up a new field for preclinical and clinical research to further investigate TIS and oncolytic viruses as an attractive combinatorial future treatment approach.

Resveratrol as a pan-HDAC inhibitor alters the acetylation status of histone [corrected] proteins in human-derived hepatoblastoma cells.

The polyphenolic alcohol resveratrol has demonstrated promising activities for the prevention and treatment of cancer. Different modes of action have been described for resveratrol including the activation of sirtuins, which represent the class III histone deacetylases (HDACs). However, little is known about the activity of resveratrol on the classical HDACs of class I, II and IV, although these classes are involved in cancer development or progression and inhibitors of HDACs (HDACi) are currently under investigation as promising novel anticancer drugs. We could show by in silico docking studies that resveratrol has the chemical structure to inhibit the activity of different human HDAC enzymes. In vitro analyses of overall HDAC inhibition and a detailed HDAC profiling showed that resveratrol inhibited all eleven human HDACs of class I, II and IV in a dose-dependent manner. Transferring this molecular mechanism into cancer therapy strategies, resveratrol treatment was analyzed on solid tumor cell lines. Despite the fact that hepatocellular carcinoma (HCC) is known to be particularly resistant against conventional chemotherapeutics, treatment of HCC with established HDACi already has shown promising results. Testing of resveratrol on hepatoma cell lines HepG2, Hep3B and HuH7 revealed a dose-dependent antiproliferative effect on all cell lines. Interestingly, only for HepG2 cells a specific inhibition of HDACs and in turn a histone hyperacetylation caused by resveratrol was detected. Additional testing of human blood samples demonstrated a HDACi activity by resveratrol ex vivo. Concluding toxicity studies showed that primary human hepatocytes tolerated resveratrol, whereas in vivo chicken embryotoxicity assays demonstrated severe toxicity at high concentrations. Taken together, this novel pan-HDACi activity opens up a new perspective of resveratrol for cancer therapy alone or in combination with other chemotherapeutics. Moreover, resveratrol may serve as a lead structure for chemical optimization of bioavailability, pharmacology or HDAC inhibition.

Preclinical evaluation of 4-methylthiobutyl isothiocyanate on liver cancer and cancer stem cells with different p53 status.

Isothiocyanates from plants of the order Brassicales are considered promising cancer chemotherapeutic phytochemicals. However, their selective cytotoxicity on liver cancer has been barely researched. Therefore, in the present study, we systematically studied the chemotherapeutic potency of 4-methylthiobutyl isothiocyanate (MTBITC). Selective toxicity was investigated by comparing its effect on liver cancer cells and their chemoresistant subpopulations to normal primary hepatocytes and liver tissue slices. Additionally, in a first assessment, the in vivo tolerability of MTBITC was investigated in mice. Growth arrest at G2/M and apoptosis induction was evident in all in vitro cancer models treated with MTBITC, including populations with cancer initiating characteristics. This was found independent from TP53; however cell death was delayed in p53 compromised cells as compared to wt-p53 cells which was probably due to differential BH3 only gene regulation i. e. Noxa and its antagonist A1. In normal hepatocytes, no apoptosis or necrosis could be detected after repeated administration of up to 50 µM MTBITC. In mice, orally applied MTBITC was well tolerated over 18 days of treatment for up to 50 mg/kg/day, the highest dose tested. In conclusion, we could show here that the killing effect of MTBITC has a definite selectivity for cancer cells over normal liver cells and its cytotoxicity even applies for chemoresistant cancer initiating cells. Our study could serve for a better understanding of the chemotherapeutic properties of isothiocyanates on human liver-derived cancer cells.

Differential induction of apoptosis and senescence by the DNA methyltransferase inhibitors 5-azacytidine and 5-aza-2'-deoxycytidine in solid tumor cells.

Epigenetic alterations are a hallmark of cancer that govern the silencing of genes. Up to now, 5-azacytidine (5-aza-CR, Vidaza) and 5-aza-2'-deoxycytidine (5-aza-dC, Dacogen) are the only clinically approved DNA methyltransferase inhibitors (DNMTi). Current effort tries to exploit DNMTi application beyond acute leukemia or myelodysplastic syndrome, especially to solid tumors. Although both drugs only differ by a minimal structural difference, they trigger distinct molecular mechanisms that are highly relevant for a rational choice of new combination therapies. Therefore, we investigated cell death pathways in vitro in human hepatoma, colon, renal, and lung cancer cells and in vivo in chorioallantoic membrane and xenograft models. Real-time cancer cell monitoring and cytokine profiling revealed a profoundly distinct response pattern to both drugs. 5-aza-dC induced p53-dependent tumor cell senescence and a high number of DNA double-strand breaks. In contrast, 5-aza-CR downregulated p53, induced caspase activation and apoptosis. These individual response patterns of tumor cells could be verified in vivo in chorioallantoic membrane assays and in a hepatoma xenograft model. Although 5-aza-CR and 5-aza-dC are viewed as drugs with similar therapeutic activity, they induce a diverse molecular response in tumor cells. These findings together with other reported differences enable and facilitate a rational design of new combination strategies to further exploit the epigenetic mode of action of these two drugs in different areas of clinical oncology.

Performance of the OTSC System in the endoscopic closure of iatrogenic gastrointestinal perforations: a systematic review.

BACKGROUND: Reliable closure is a prerequisite for conventional and innovative endoscopic procedures, such as NOTES. The purpose of this study is the systematic evaluation of the procedural and clinical success rates in closure of iatrogenic gastrointestinal perforations and acute anastomotic leaks by means of the over-the-scope-clip system (OTSC(®)). DESIGN: PubMed and other sources were searched systematically for clinical and preclinical research on the evaluation of the OTSC System for closure of gastrointestinal perforations and leaks. Appraisal of studies for inclusion and data extraction was performed independently by two reviewers using an a priori determined data extraction grid. Major endpoints to be extracted were data on procedural success (successful clip application) and clinical access (durable closure of defect without secondary adjunct therapy). RESULTS: A total of 17 clinical research articles/abstracts and 22 preclinical research articles/abstracts were identified. The examined clinical studies comprised case series and clinical single-arm studies. The reviewed studies revealed a consistently high mean rate of procedural success of 80-100 % and durable clinical success of 57-100 %. An identified major drawback preventing successful clip application was occurrence of fibrotic or inflamed lesion edges. Usage of the OTSC System was accompanied by neither major clip-related nor application-related complication. In experimental settings, closure of larger perforations and gastric access sites of NOTES or endoscopic full-thickness resection were achieved with high rates of success. CONCLUSIONS: Because randomized, clinical trials are not available in this field of indication, the evaluation is based on small case series. Nevertheless, by pooling all experience gained, we conclude that endoscopic closure of iatrogenic gastrointestinal perforations and acute anastomotic leaks by means of the OTSC System is a safe and effective method.

Innate immune defense defines susceptibility of sarcoma cells to measles vaccine virus-based oncolysis.

The oncolytic potential of measles vaccine virus (MeV) has been demonstrated in several tumor entities. Here, we investigated the susceptibility of eight sarcoma cell lines to MeV-mediated oncolysis and found five to be susceptible, whereas three proved to be resistant. In the MeV-resistant cell lines, we often observed an inhibition of viral replication along with a strong upregulation of the intracellular virus-sensing molecule RIG-I and of the interferon (IFN)-stimulated gene IFIT1. Not only expression of IFIT1 but also phosphorylation of IFN-stimulated Stat1 took place rapidly and were found to be persistent over time. In contrast, susceptible cell lines showed a much weaker, delayed, or completely missing expression of IFIT1 as well as a delayed or only transient phosphorylation of Stat1, whereas exogenic stimulation with beta interferon (IFN-ß) resulted in a comparable profound activation of Stat1 and expression of IFIT1 in all cell lines. Pretreatment with IFN-ß rendered three of the susceptible cell lines more resistant to MeV-mediated oncolysis. These data suggest that differences in the innate immune defense often account for different degrees of susceptibility of sarcoma cell lines to MeV-mediated oncolysis. From a therapeutic perspective, we were able to overcome resistance to MeV by increasing the multiplicity of infection (MOI) and by addition of the prodrug 5-fluorocytosine (FC), thereby exploiting the suicide gene function of virotherapeutic vector MeV-SCD armed with the SCD fusion protein, which consists of yeast cytosine deaminase and yeast uracil phosphoribosyltransferase.

Kaempferol, a new nutrition-derived pan-inhibitor of human histone deacetylases.

Kaempferol is a natural polyphenol belonging to the group of flavonoids. Different biological functions like inhibition of oxidative stress in plants or animal cells and apoptosis induction have been directly associated with kaempferol. The underlying mechanisms are only partially understood. Here we report for the first time that kaempferol has a distinct epigenetic activity by inhibition of histone deacetylases (HDACs). In silico docking analysis revealed that it fits into the binding pocket of HDAC2, 4, 7 or 8 and thereby binds to the zinc ion of the catalytic center. Further in vitro profiling of all conserved human HDACs of class I, II and IV showed that kaempferol inhibited all tested HDACs. In clinical oncology, HDAC inhibitors are currently under investigation as new anticancer compounds. Therefore, we studied the effect of kaempferol on human-derived hepatoma cell lines HepG2 and Hep3B as well as on HCT-116 colon cancer cells and found that it induces hyperacetylation of histone complex H3. Furthermore, kaempferol mediated a prominent reduction of cell viability and proliferation rate. Interestingly, toxicity assays revealed signs of relevant cellular toxicity in primary human hepatocytes only starting at 50 µM as well as in an in vivo chicken embryotoxicity assay at 200 µM. In conclusion, the identification of a novel broad inhibitory capacity of the natural compound kaempferol for human-derived HDAC enzymes opens up the perspective for clinical application in both tumor prevention and therapy. Moreover, kaempferol may serve as a novel lead structure for chemical optimization of pharmacokinetics, pharmacology or inhibitory activities.

Selective protection of human liver tissue in TNF-targeting of cancers of the liver by transient depletion of adenosine triphosphate.

BACKGROUND: Tumor necrosis factor alpha (TNF) is able to kill cancer cells via receptor-mediated cell death requiring adenosine triphosphate (ATP). Clinical usage of TNF so far is largely limited by its profound hepatotoxicity. Recently, it was found in the murine system that specific protection of hepatocytes against TNF's detrimental effects can be achieved by fructose-mediated ATP depletion therein. Before employing this quite attractive selection principle in a first clinical trial, we here comprehensively investigated the interdependence between ATP depletion and TNF hepatotoxicity in both in vitro and ex vivo experiments based on usage of primary patient tissue materials. METHODS: Primary human hepatocytes, and both non-tumorous and tumorous patient-derived primary liver tissue slices were used to elucidate fructose-induced ATP depletion and TNF-induced cytotoxicity. RESULTS: PHH as well as tissue slices prepared from non-malignant human liver specimen undergoing a fructose-mediated ATP depletion were both demonstrated to be protected against TNF-induced cell death. In contrast, due to tumor-specific overexpression of hexokinase II, which imposes a profound bypass on hepatocytic-specific fructose catabolism, this was not the case for human tumorous liver tissues. CONCLUSION: Normal human liver tissues can be protected transiently against TNF-induced cell death by systemic pretreatment with fructose used in non-toxic/physiologic concentrations. Selective TNF-targeting of primary and secondary tumors of the liver by transient and specific depletion of hepatocytic ATP opens up a new clinical avenue for the TNF-based treatment of liver cancers.

Performance of the OTSC System in the endoscopic closure of gastrointestinal fistulae--a meta-analysis.

BACKGROUND: Conventional endoscopic treatment options for closure of gastrointestinal fistulae are impaired by several limitations and therefore yield high rates of recurrence. Aim of the study is the evaluation of the primary-technical and secondary-clinical success rates in closure of gastrointestinal fistulae by means of the OTSC System. DESIGN/METHODS: The database Medline was systematically searched for primary research on the evaluation of the OTSC System in closure of gastrointestinal fistulae. Appraisal of studies for inclusion and data extraction were performed independently by two reviewers using an a priori determined data extraction grid. RESULTS: A total of 19 primary research articles were identified. The examined studies comprised case reports as well as case series and clinical single-arm studies (n = 7) with a limited number of participants. Reviewed studies revealed a high rate of procedural success (mean 84.6%; 95% confidence interval 66.6 to 93.8%) and durable clinical success (mean 69.0%; 95% confidence interval 51.8 to 82.2%). Failed attempts and incomplete closures were mainly ascribed to the challenging effort of treating highly fibrotic chronic fistulae. CONCLUSION: Endoscopic closure of gastrointestinal fistulae by means of the OTSC System is a safe and effective method.

Kinetic tracking of therapy-induced senescence using the real-time cell analyzer single plate system.

In recent years, terminal growth arrest, that is, senescence, especially therapy-induced senescence (TIS), has become a major subject in cancer research and several fields of life sciences. Senescence is characterized by a specific set of morphological and biochemical changes. However, methods that evidence senescence induction are still very limited and show large variation between individual examiners. Most notably, these assays are classical endpoint assays, and, therefore, screening for senescence is time consuming and expensive. Here, we describe an efficient, simple, and objective method to screen for TIS over time by modifying the Real-Time Cell Analyzer SP system, thus enabling to pin point the induction of senescence. This method continuously detects the cell's impedance in each well of a 96-microwell plate that allows to observe increment of cell size, a hallmark feature of cellular senescence. This technique is suitable for high-throughput TIS screening by measuring several compounds, small molecules, and/or cell lines simultaneously.

Fructose protects murine hepatocytes from tumor necrosis factor-induced apoptosis by modulating JNK signaling.

Fructose-induced hepatic ATP depletion prevents TNF-induced apoptosis, whereas it contrarily enhances CD95-induced hepatocyte apoptosis in vitro and in vivo. By contrast, transformed liver cells are not protected against TNF due to metabolic alterations, allowing selective tumor targeting. We analyzed the molecular mechanisms by which fructose modulates cytokine-induced apoptosis. A release of adenosine after fructose-induced ATP depletion, followed by a cAMP response, was demonstrated. Likewise, cAMP and adenosine mimicked per se the modulation by fructose of CD95- and TNF-induced apoptosis. The effects of fructose on cytokine-induced apoptosis were sensitive to inhibition of protein kinase A. Fructose prevented the pro-apoptotic, sustained phase of TNF-induced JNK signaling and thereby blocked bid-mediated activation of the intrinsic mitochondrial apoptosis pathway in a PKA-dependent manner. We explain the dichotomal effects of fructose on CD95- and TNF-induced cell death by the selective requirement of JNK signaling for the latter. These findings provide a mechanistic rationale for the protection of hepatocytes from TNF-induced cell death by pharmacological doses of fructose.

Preclinical testing of virotherapeutics for primary and secondary tumors of the liver.

Virotherapy offers a new treatment strategy using oncolytic viruses as self-replicating, tumor-specific agents, which destroy tumors during their natural lytic replication process. To study potential oncolytic viruses, cell culture experiments give basic information about the lytic potential of a virus, measured as cell lysis or decreased viability. For further analysis, animal models are usually employed. As these in vivo experiments are often performed in immunocompromised animals, results have to be interpreted with caution. Therefore, to obtain deeper information of the oncolytic action of specific viruses in a patient's individual context we established a test platform based on human primary tissue slices. In this three-dimensional model, we observed a preferential tumor infection and the penetration of oncolytic measles vaccine virus into deeper cell layers of tumor tissues, which is an essential feature of an effective oncolytic virus.

Dual antitumour effect of 5-azacytidine by inducing a breakdown of resistance-mediating factors and epigenetic modulation.

BACKGROUND: The cytokine tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) has shown promising anticancer activity in early clinical settings by selectively inducing apoptosis in different tumour types. However, some tumour entities such as hepatocellular carcinoma (HCC) display an inherent resistance to TRAIL. A huge effort has been made to unravel strategies for a clinically applicable sensitisation of resistant cancer cells to TRAIL. Reversible epigenetic alterations such as DNA methylation play a major role in development, maintenance and resistance phenomena of tumour cells. Currently, several clinical trials are exploiting the potential of epigenetic drugs, such as 5-azacytidine (5-aza-CR) or 5-aza-2'-deoxycytidine (5-aza-dC) to break primary or secondary resistance phenomena of cancer cells. Therefore, 5-aza-CR and 5-aza-dC were investigated in the context of TRAIL resistance. METHODS: Alterations in proliferation, apoptosis, regulatory proteins and toxicity were investigated in TRAIL-resistant hepatoma, and also in renal, colon and pancreatic cancer cells as well as non-transformed human-derived primary hepatocytes, tissue slices isolated from human liver and non-malignant colon cells, all of which had been exposed to demethylating drugs and/or TRAIL. RESULTS: Within hours, 5-aza-CR but not 5-aza-dC sensitised in vitro cultured tumour cells to TRAIL, first by activating caspases, followed by a subsequent induction of apoptosis. This surprisingly rapid sensitisation was confirmed in vivo employing a chorioallantoic membrane assay. As a major mechanism, a 5-aza-CR-induced inhibition of cellular protein synthesis was found which led to a breakdown of tumour-protecting factors such as the antiapoptotic factor FLICE inhibitory protein (FLIP). Importantly, TRAIL and 5-aza-CR did not induce relevant toxicity or apoptosis in primary hepatocytes, liver slices from different human donors and in normal colon cells. CONCLUSIONS: Molecular evidence is provided for a novel 5-aza-CR-based translational approach enabling a twofold treatment of apoptosis-resistant tumour entities, not only by an epigenetic reversion of the malignancy-associated phenotype but also by an efficient resensitization to apoptosis-inducing substances such as TRAIL.

Differential immunotoxicity of histone deacetylase inhibitors on malignant and naïve hepatocytes.

Histone deacetylases (HD) represent a novel target in cancer treatment, particularly for scattered small tumours such as the hepatocellular carcinoma (HCC). However, only few studies address the toxicological impact of HD Inhibitors (HDIs) on malignantly transformed cells versus primary hepatocytes. We examined whether and how different classes of HDIs sensitise the human HCC cell line HepG2, primary healthy murine and human liver cells towards the death receptor agonists TNFα and CD95L. Apicidin, M344 (N-hydroxy-7-(-4-dimethylaminobenzol)aminoheptanamide), CBHA (m-carboxycinnamic acid bis-hydroxamide) and VPA (valproic acid) sensitised liver cell cultures towards CD95-triggered apoptosis with the following potency: apicidin > M344 ≈ CBHA ≫ VPA. Apicidin sensitised towards CD95 also in the intact organ, i.e. in the isolated perfused mouse liver. No significant sensitisation towards TNFα was found in vitro. Western blot analysis showed that all HDIs studied downregulated the anti-apoptotic protein cFLIP, but only VPA additionally affected the expression level of XIAP. Furthermore, in models of the intrinsic apoptosis pathway, i.e. in HepG2 cells treated with Melphalan and in primary hepatocytes irradiated with UV light, only VPA exhibited significant sensitisation. These findings extend the biochemical, pharmacological and toxicological basis for HDI therapy and provide a caveat for clinical use in patients with an accompanying critical inflammatory state in which the CD95 system might be pre-activated.

Malignant but not naïve hepatocytes of human and rodent origin are killed by TNF after metabolic depletion of ATP by fructose.

BACKGROUND & AIMS: TNF was the first cytokine employed for cancer therapy, but its use was limited due to its insufficient selectivity towards malignant cells. Fructose induces transient hepatic ATP depletion in humans and rodents due to the liver-specific fructose metabolism via fructokinase, while other cells e.g. Muscle cells metabolize fructose via hexokinase. Under ATP depleted conditions hepatocytes are protected against TNF-induced apoptosis. Our aim was to identify metabolic differences between normal and malignant liver cells that can be exploited for selective immunotherapy. METHODS: We analyzed the expression and activities of enzymes involved in fructose metabolism in primary hepatocytes and hepatoma cell lines. Furthermore, we studied the influence of hexokinase II (HKII) on fructose-mediated ATP depletion and cytoprotection in murine hepatocytes. RESULTS: Primary mouse, rat and human hepatocytes depleted of ATP by fructose were fully protected against TNF-induced cytotoxicity. By contrast, hepatic tumor cell lines showed increased HKII expression, lack of fructose-mediated ATP depletion and, therefore, remained susceptible to TNF/ActD-induced apoptosis. Inhibition of hexokinases restored fructose-induced ATP depletion in hepg2 cells. Finally, hypoxia-inducible factor1 (HIF1)-mediated up-regulation of HKII prevented fructose-induced ATP depletion and overexpression of HKII inhibited fructose-mediated cytoprotection against TNF-induced apoptosis in primary murine hepatocytes. CONCLUSION: Increased expression of HKII in malignant cells of hepatic origin shifts the fructose metabolism from liver- to muscle-type, thereby preventing ATP depletion and subsequent cytoprotection of the target cells. Therefore, healthy liver cells are transiently protected from TNF-mediated cell death by fructose-induced ATP depletion, while malignant cells can be selectively eliminated through TNF-induced apoptosis.