Increased HRD score in cisplatin resistant penile cancer cells

BACKGROUND/INTRODUCTION

Penile cancer is a rare disease in demand for new therapeutic options. Frequently used combination chemotherapy with 5 fluorouracil (5-FU) and cisplatin (CDDP) in patients with metastatic penile cancer mostly results in the development of acquired drug resistance. Availability of cell culture models with acquired resistance against standard therapy could help to understand molecular mechanisms underlying chemotherapy resistance and to identify candidate treatments for an efficient second line therapy.

METHODS

We generated a cell line from a humanpapilloma virus (HPV) negative penile squamous cell carcinoma (UKF-PEC-1). This cell line was subject to chronic exposure to chemotherapy with CDDP and / or 5-FU to induce acquired resistance in the newly established chemo-resistant sublines (PEC-1^rCDDP²⁵⁰⁰, adapted to 2500 ng/ml CDDP; UKF-PEC-1^r5-FU⁵⁰⁰, adapted to 500 ng/ml 5- FU; UKF-PEC1^rCDDP²⁵⁰⁰/^r5-FU⁵⁰⁰, adapted to 2500 ng/ml CDDP and 500 ng/ml 5 -FU). Afterwards cell line pellets were formalin-fixed, paraffin embedded and subject to sequencing as well as testing for homologous recombination deficiency (HRD). Additionally, exemplary immunohistochemical stainings for p53 and gammaH2AX were applied for verification purposes. Finally, UKF-PEC-1^rCDDP²⁵⁰⁰, UKF-PEC-1^r5-FU⁵⁰⁰, UKF-PEC1^rCDDP²⁵⁰⁰/^r5-FU⁵⁰⁰, and UKF-PEC-3 (an alternative penis cancer cell line) were tested for sensitivity to paclitaxel, docetaxel, olaparib, and rucaparib.

RESULTS AND CONCLUSIONS

The chemo-resistant sublines differed in their mutational landscapes. UKF-PEC-1^rCDDP²⁵⁰⁰ was characterized by an increased HRD score, which is supposed to be associated with increased PARP inhibitor and immune checkpoint inhibitor sensitivity in cancer. However, UKF-PEC-1^rCDDP²⁵⁰⁰ did not display sensitivity to PARP inhibitors.

Value of c-MET and Associated Signaling Elements for Predicting Outcomes and Targeted Therapy in Penile Cancer

Simple Summary

No relevant improvement in patient outcomes could be achieved in the last decade in metastasized penile cancer due to insufficient identification of molecular hubs crucial for tumor evolution. We investigated the potential of the cellular receptor c-MET and selected other proteins linked to its activity to predict outcomes and for exploitation in targeted treatment. Assessing tumor tissue as well as primary cells both naïve and resistant to systemic drugs, we illustrate the most promising role of c-MET. Indeed, its elevated expression was strongly associated with inferior tumor-related survival. Moreover, its upregulation in treatment-resistant cell lines compared to naïve cells was observed. Treating cell lines with the c-MET inhibitors cabozantinib and tivantinib mediated an effective decrease in cell growth, while the first agent was more efficacious in the naïve cells and the second agent in the resistant cells. Therefore, c-MET blockade warrants further investigation in the setting of metastasized penile cancer.

Abstract

Whereas the lack of biomarkers in penile cancer (PeCa) impedes the development of efficacious treatment protocols, preliminary evidence suggests that c-MET and associated signaling elements may be dysregulated in this disorder. In the following study, we investigated whether c-MET and associated key molecular elements may have prognostic and therapeutic utility in PeCa. Formalin-fixed, paraffin-embedded tumor tissue from therapy-naïve patients with invasive PeCa was used for tissue microarray (TMA) analysis. Immunohistochemical staining was performed to determine the expression of the proteins c-MET, PPARg, β-catenin, snail, survivin, and n-MYC. In total, 94 PeCa patients with available tumor tissue were included. The median age was 64.9 years. High-grade tumors were present in 23.4%, and high-risk HPV was detected in 25.5%. The median follow-up was 32.5 months. High expression of snail was associated with HPV-positive tumors. Expression of β-catenin was inversely associated with grading. In both univariate COX regression analysis and the log-rank test, an increased expression of PPARg and c-MET was predictive of inferior disease-specific survival (DSS). Moreover, in multivariate analysis, a higher expression of c-MET was independently associated with worse DSS. Blocking c-MET with cabozantinib and tivantinib induced a significant decrease in viability in the primary PeCa cell line UKF-PeC3 isolated from the tumor tissue as well as in cisplatin- and osimertinib-resistant sublines. Strikingly, a higher sensitivity to tivantinib could be detected in the latter, pointing to the promising option of utilizing this agent in the second-line treatment setting.

Novel SARS-CoV-2 variants induce higher toxicity in cardiovascular cells

Objective

SARS-CoV-2 causes the coronavirus disease 2019 (COVID-19) and has spawned a global health crisis. Virus infection can lead to elevated markers of cardiac injury and inflammation associated with a higher risk of mortality. However, it is so far unclear whether cardiovascular damage is caused by direct virus infection or is mainly secondary due to inflammation. Recently, additional novel SARS-CoV-2 variants have emerged accounting for more than 70% of all cases in Germany. To what extend these variants differ from the original strain in their pathology remains to be elucidated.

Here, we investigated the effect of the novel SARS-CoV-2 variants on cardiovascular cells.

Results

To study whether cardiovascular cells are permissive for SARS-CoV-2, we inoculated human iPS-derived cardiomyocytes and endothelial cells from five different origins, including umbilical vein endothelial cells, coronary artery endothelial cells (HCAEC), cardiac and lung microvascular endothelial cells, or pulmonary arterial cells, in vitro with SARS-CoV-2 isolates (G614 (original strain), B.1.1.7 (British variant), B.1.351 (South African variant) and P.1 (Brazilian variant)).

While the original virus strain infected iPS-cardiomyocytes and induced cell toxicity 96h post infection (290±10 cells vs. 130±10 cells; p=0.00045), preliminary data suggest a more severe infection by the novel variants. To what extend the response to the novel variants differ from the original strain is currently investigated by phosphoproteom analysis.

Of the five endothelial cells studied, only human coronary artery EC took up the original virus strain, without showing viral replication and cell toxicity. Spike protein was only detected in the perinuclear region and was co-localized with calnexin-positive endosomes, which was accompanied by elevated ER-stress marker genes, such as EDEM1 (1.5±0.2-fold change; p=0.04). Infection with the novel SARS-CoV-2 variants resulted in significant higher levels of viral spike compared to the current strain. Surprisingly, viral up-take was also seen in other endothelial cell types (e.g. HUVEC). Although no viral replication was observed (850±158 viral RNA copies at day 0 vs. 197±43 viral RNA copies at day 3; p=0.01), the British SARS-CoV-2 variant B.1.1.7 reduced endothelial cell numbers (0.63±0.03-fold change; p=0.0001).

Conclusion

Endothelial cells and cardiomyocytes showed a distinct response to SARS-CoV-2. Whereas cardiomyocytes were permissively infected, endothelial cells took up the virus, but were resistant to viral replication. However, both cell types showed signs of increased toxicity induced by the British SARS-CoV-2 variant. These data suggest that cardiac complications observed in COVID-19 patients might at least in part be based on direct infection of cardiovascular cells. The more severe cytotoxic effects of the novel variants implicate that patients infected with the new variants should be even more closely monitored.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): DFG and Willy-Pitzer Foundation

Detection and infectivity of SARS-CoV-2 in exhumated corpses

Postmortem detection of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) after the exhumation of a corpse can become important, e.g. in the case of subsequent medical malpractice allegations. To date, data on possible detection periods [e.g. by reverse transcription polymerase chain reaction (RT-PCR)] or on the potential infectivity of the virus after an exhumation are rare. In the present study, these parameters were examined in two cases with a time span of approximately 4 months between day of death and exhumation. Using SARS-CoV-2 RT-PCR on swabs of both lungs and the oropharynx detection was possible with cycle threshold (C_t) values of about 30 despite signs of beginning decay. RT-PCR testing of perioral and perinasal swabs and swabs collected from the inside of the body bag, taken to estimate the risk of infection of those involved in the exhumation, was negative. Cell culture-based infectivity testing was negative for both, lung and oropharyngeal swabs. In one case, RT-PCR testing at the day of death of an oropharyngeal swab showed almost identical C_t values as postmortem testing of an oropharyngeal swab, impressively demonstrating the stability of viral RNA in the intact corpse. However, favorable climatic conditions in the grave have to be taken into account, as it was wintertime with constant low temperatures. Nevertheless, it was possible to demonstrate successful postmortem detection of SARS-CoV-2 infection following exhumation even after months in an earth grave.

Assessment of PI3K/mTOR/AKT Pathway Elements to Serve as Biomarkers and Therapeutic Targets in Penile Cancer

The PI3K/mTOR/AKT pathway might represent an intriguing option for treatment of penile cancer (PeCa). We aimed to assess whether members of this pathway might serve as biomarkers and targets for systemic therapy. Tissue of primary cancer from treatment-naïve PeCa patients was used for tissue microarray analysis. Immunohistochemical staining was performed with antibodies against AKT, pAKT, mTOR, pmTOR, pS6, pPRAS, p4EBP1, S6K1 and pp70S6K. Protein expression was correlated with clinicopathological characteristics as well as overall survival (OS), disease-specific survival (DSS), recurrence-free survival (RFS) and metastasis-free survival (MFS). AKT inhibition was tested in two primarily established, treatment-naïve PeCa cell lines by treatment with capivasertib and analysis of cell viability and chemotaxis. A total of 76 patients surgically treated for invasive PeCa were included. Higher expression of AKT was significantly more prevalent in high-grade tumors and predictive of DSS and OS in the Kaplan-Meier analysis, and an independent predictor of worse OS and DSS in the multivariate regression analysis. Treatment with pan-AKT inhibitor capivasertib in PeCa cell lines induced a significant downregulation of both total AKT and pAKT as well as decreased cell viability and chemotaxis. Selected protein candidates of the mTOR/AKT signaling pathway demonstrate association with histological and survival parameters of PeCa patients, whereas AKT appears to be the most promising one.

Infectivity of deceased COVID-19 patients

The duration of infectivity of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) in living patients has been demarcated. In contrast, a possible SARS-CoV-2 infectivity of corpses and subsequently its duration under post mortem circumstances remain to be elucidated. The aim of this study was to investigate the infectivity and its duration of deceased COVID-19 (coronavirus disease) patients. Four SARS-CoV-2 infected deceased patients were subjected to medicolegal autopsy. Post mortem intervals (PMI) of 1, 4, 9 and 17 days, respectively, were documented. During autopsy, swabs and organ samples were taken and examined by RT-qPCR (real-time reverse transcription-polymerase chain reaction) for the detection of SARS-CoV-2 ribonucleic acid (RNA). Determination of infectivity was performed by means of virus isolation in cell culture. In two cases, virus isolation was successful for swabs and tissue samples of the respiratory tract (PMI 4 and 17 days). The two infectious cases showed a shorter duration of COVID-19 until death than the two non-infectious cases (2 and 11 days, respectively, compared to > 19 days), which correlates with studies of living patients, in which infectivity could be narrowed to about 6 days before to 12 days after symptom onset. Most notably, infectivity was still present in one of the COVID-19 corpses after a post-mortem interval of 17 days and despite already visible signs of decomposition. To prevent SARS-CoV-2 infections in all professional groups involved in the handling and examination of COVID-19 corpses, adequate personal safety standards (reducing or avoiding aerosol formation and wearing FFP3 [filtering face piece class 3] masks) have to be enforced for routine procedures.

Testing of the Survivin Suppressant YM155 in a Large Panel of Drug-Resistant Neuroblastoma Cell Lines

The survivin suppressant YM155 is a drug candidate for neuroblastoma. Here, we tested YM155 in 101 neuroblastoma cell lines (19 parental cell lines, 82 drug-adapted sublines). Seventy seven (77) cell lines displayed YM155 IC₅₀s in the range of clinical YM155 concentrations. ABCB1 was an important determinant of YM155 resistance. The activity of the ABCB1 inhibitor zosuquidar ranged from being similar to that of the structurally different ABCB1 inhibitor verapamil to being 65-fold higher. ABCB1 sequence variations may be responsible for this, suggesting that the design of variant-specific ABCB1 inhibitors may be possible. Further, we showed that ABCC1 confers YM155 resistance. Previously, p53 depletion had resulted in decreased YM155 sensitivity. However, TP53-mutant cells were not generally less sensitive to YM155 than TP53 wild-type cells in this study. Finally, YM155 cross-resistance profiles differed between cells adapted to drugs as similar as cisplatin and carboplatin. In conclusion, the large cell line panel was necessary to reveal an unanticipated complexity of the YM155 response in neuroblastoma cell lines with acquired drug resistance. Novel findings include that ABCC1 mediates YM155 resistance and that YM155 cross-resistance profiles differ between cell lines adapted to drugs as similar as cisplatin and carboplatin.

Human Immunodeficiency Virus Resistance to AZT in MOLT4/8 Cells is Associated with a Lack of AZT Phosphorylation and is Bypassed by AZT-Monophosphate SATE Prodrugs

Human T lymphoid MOLT4/8 cells were grown continuously for more than 2 years in a medium containing 3′-azido-2′,3′-dideoxythymidine (zidovudine; AZT) at a concentration of 250 μM. These cells, designated MOLT-4/8rAZT250, were used to test the cytotoxic and antiviral activity of AZT. Intracellular accumulation of AZT, expression of the multidrug resistance 1 (MDR-1) gene, thymidine kinase (TK) gene and activity of the TK enzyme in cellular extracts were measured. The results showed that both the cytotoxic and antiviral activity of AZT were significantly lower in MOLT4/8rAZT250 than in MOLT4/8 cells; concentrations required to inhibit 50% production of the p24 human immunodeficiency virus type 1 (HIV-1) antigen of two laboratory strains were at least 100-fold higher in resistant cells. The MDR-1 gene was not expressed in the resistant cells. TK mRNA expression was significantly lower in the resistant than in the sensitive cells. TK enzymatic activity for deoxythymidine phosphorylation was impaired in MOLT4/8rAZT250 cells compared to the sensitive cells. AZT was phosphorylated only in the sensitive cells whereas no phosphorylation of AZT was found in the resistant cells. We tested whether several AZT-monophosphate triesters, which bypass cellular TK, could overcome resistance to the cytotoxic and antiviral activity of AZT. The bis( t-butylSATE) phosphotriester derivative of AZT showed comparable cytotoxic and antiviral activity in sensitive and resistant cells. The results demonstrated that MOLT4/8rAZT250 cells exert resistance to the anti-HIV activity of the drug mainly owing to the lack of AZT phosphorylation and that resistance may be bypassed by using AZT-monophosphate SATE prodrugs.

Correlation from undiluted vitreous cytokines of untreated central retinal vein occlusion with spectral domain optical coherence tomography

PURPOSE

To correlate inflammatory and proangiogenic key cytokines from undiluted vitreous of treatment-naïve central retinal vein occlusion (CRVO) patients with SD-OCT parameters.

METHODS

Thirty-five patients (age 71.1 years, 24 phakic, 30 nonischemic) underwent intravitreal combination therapy, including a single-site 23-gauge core vitrectomy. Twenty-eight samples from patients with idiopathic, non-uveitis floaterectomy served as controls. Interleukin 6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor (VEGF-A) levels were correlated with the visual acuity (logMar), category of CRVO (ischemic or nonischemic) and morphologic parameters, such as central macular thickness-CMT, thickness of neurosensory retina-TNeuro, extent of serous retinal detachment-SRT and disintegrity of the IS/OS and others.

RESULTS

The mean IL-6 was 64.7pg/ml (SD ± 115.8), MCP-1 1015.7 ( ± 970.1), and VEGF-A 278.4 ( ± 512.8), which was significantly higher than the control IL-6 6.2 ± 3.4pg/ml (P=0.06), MCP-1 253.2 ± 73.5 (P<0.0000001) and VEGF-A 7.0 ± 4.9 (P<0.0006). All cytokines correlated highly with one another (correlation coefficient r=0.82 for IL-6 and MCP-1; r=0.68 for Il-6 and VEGF-A; r=0.64 for MCP-1 and VEGF-A). IL-6 correlated significantly with CMT, TRT, SRT, dIS/OS, and dELM. MCP-1 correlated significantly with SRT, dIS/OS, and dELM. VEGF-A correlated not with changes in SD-OCT, while it had a trend to be higher in the ischemic versus the nonischemic CRVO group (P=0.09).

CONCLUSIONS

The inflammatory cytokines were more often correlated with morphologic changes assessed by SD-OCT, whereas VEGF-A did not correlate with CRVO-associated changes in SD-OCT. VEGF inhibition alone may not be sufficient in decreasing the inflammatory response in CRVO therapy.

Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents

Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3, also disrupts the p53/Mdm2 interaction. All of the 11 UKF-NB-3 sub-lines adapted to RITA that we established retained functional wild-type p53 although RITA induced a substantial p53 response. Moreover, all RITA-adapted cell lines remained sensitive to nutlin-3, whereas only five out of 10 nutlin-3-adapted cell lines retained their sensitivity to RITA. In addition, repeated adaptation of the RITA-adapted sub-line UKF-NB-3^rRITA^10 μM to nutlin-3 resulted in p53 mutations. The RITA-adapted UKF-NB-3 sub-lines displayed no or less pronounced resistance to vincristine, cisplatin, and irradiation than nutlin-3-adapted UKF-NB-3 sub-lines. Furthermore, adaptation to RITA was associated with fewer changes at the expression level of antiapoptotic factors than observed with adaptation to nutlin-3. Transcriptomic analyses indicated the RITA-adapted sub-lines to be more similar at the gene expression level to the parental UKF-NB-3 cells than nutlin-3-adapted UKF-NB-3 sub-lines, which correlates with the observed chemotherapy and irradiation sensitivity phenotypes. In conclusion, RITA-adapted cells retain functional p53, remain sensitive to nutlin-3, and display a less pronounced resistance phenotype than nutlin-3-adapted cells.

Recent publications in medical microbiology and immunology: a retrospective

A look back is done to some clinical and basic research activities recently published in medical microbiology and immunology. The review covers clinical experiences and in vitro experiments to understand the emergency, pathogenicity, epidemic spread, and vaccine-based prevention of avian and swine-origin flu. Some new developments and concepts in diagnosis, (molecular) epidemiology, and therapy of AIDS, viral hepatitis C, and herpesvirus-associated diseases are outlined. Regulation of immune system has been discussed in a special issue 2010 including some aspects of CNS affections (measles). Mycobacterial infection and its prevention by modern recombinant vaccines have reached new interest, as well as new concepts of vaccination and prophylaxis against several other bacteria. Adaptation to host niches enables immune escape (example brucella) and determines virulence (example N. meningitidis). Chlamydia pneumoniae, previously considered to trigger atherosclerosis, is hypothetically associated to Alzheimer disease, while CMV, another putative trigger of atherosclerosis, gains evidence of oncomodulation in CNS tumor diseases. In terms of globalization, exotic virus infections are increasingly imported from southern countries.

Doxorubicin-induced cell death requires cathepsin B in HeLa cells

The cysteine protease cathepsin B acts as a key player in apoptosis. Cathepsin B-mediated cell death is induced by various stimuli such as ischemia, bile acids or TNFα. Whether cathepsin B can be influenced by anticancer drugs, however, has not been studied in detail. Here, we describe the modulation of doxorubicin-induced cell death by silencing of cathepsin B expression. Previously, it was shown that doxorubicin, in contrast to other drugs, selectively regulates expression and activity of cathepsin B. Selective silencing of cathepsin B by siRNA or the cathepsin B specific inhibitor CA074Me modified doxorubicin-mediated cell death in Hela tumor cells. Both Caspase 3 activation and PARP cleavage were significantly reduced in cells lacking cathepsin B. Moreover, mitochondrial membrane permeabilization as well as the release of cytochrome C and AIF from mitochondria into cytosol induced by doxorubicin were significantly diminished in cathepsin B suppressed cells. In addition, doxorubicin associated down-regulation of XIAP was not observed in cathepsin B silenced cells. Lack of cathepsin B significantly modified cell cycle regulatory proteins such as cdk1, Wee1 and p21 without significant changes in G(1), S or G(2)M cell cycle phases maybe indicating further cell cycle independent actions of these proteins. Consequently, cell viability following doxorubicin was significantly elevated in cells with cathepsin B silencing. In summary, our data strongly suggest a role of cathepsin B in doxorubicin-induced cell death. Therefore, increased expression of cathepsin B in various types of cancer can modify susceptibility towards doxorubicin.

Human immunodeficiency virus type-1 group M quasispecies evolution: diversity and divergence in patients co-infected with active tuberculosis

The evolution of intra-host human immunodeficiency virus type 1 (HIV-1) quasispecies prior and after treating active tuberculosis (TB) with chemotherapy in HIV-1/TB patients was assessed. Two time points HIV-1 quasispecies were evaluated by comparing HIV-1-infected patients with active tuberculosis (HIV-1/TB) and HIV-1-infected patients without tuberculosis (HIV-1/non-TB). Plasma samples were obtained from the Frankfurt HIV cohort, and HIV-1 RNA was isolated. C2V5 env was amplified by PCR and molecular cloning was performed. Eight to twenty-five clones were sequenced from each patient. Various phylogenetic analyses were performed. We found a significant increase in diversity and divergence in HIV-1/TB compared to the HIV-1/non-TB. For HIV-1/TB, the average rate of evolution of C2V5 env was higher than previous reports (2.4 × 10(-4) substitution/site/day). Two groups of HIV-1/TB were observed based on the rate of HIV-1 evolution and coreceptor usage: A fast evolving R5-tropic dominating group and a relatively slowly evolving X4 group. The results demonstrated that active TB has an impact on HIV-1 viral diversity and divergence over time. The influence of active TB on longitudinal evolution of HIV-1 may be predominant for R5 viruses.

Determination of serum antibodies against swine-origin influenza A virus H1N1/09 by immunofluorescence, haemagglutination inhibition, and by neutralization tests: how is the prevalence rate of protecting antibodies in humans?

In April 2009, a new variant of influenza A virus, subtype H1N1v emerged in Mexico and spread all over the world producing the H1N1 pandemic in mankind after 1918-1920 and 1978/1979. Obviously there was no herd immunity against this new virus variant. Mainly young people, but less elderly were affected and presented severe and even lethal courses of disease. Since virus-specific antibodies are commonly regarded as markers of partial or complete immunoprotection, we performed antibody determinations in serum samples obtained from people before and after the pandemic has arrived in our region (Frankfurt/M., Germany). The assays were done by indirect immunofluorescence, by neutralization test, and by a haemagglutination inhibition test (HI), which was established in a practical modification for general and easy use. Among 145 individuals, of whom serum specimens had been drawn before the onset of pandemic, 19 revealed humoral immunity, i.e. titres of H1N1v neutralizing antibodies (at least 1:64). Eleven were older than 60 years, one belonged to the age group 40-59 years, three to the age group 20-39 years, and two to the age group 15-19 years. After the onset of pandemic in Frankfurt, serum specimens drawn from n = 225 randomly selected patients of our local university hospital were investigated for antibodies against H1N1v by HI, which is generally recommended for routine check of immunity. Twenty-eight individuals revealed the protecting antibody titre of at least 1:40. The age distribution had moved to mean age groups. The results fit to the incidence of influenza A/H1N1(09) disease, as confirmed by RT-PCR in patients admitted to our hospital, peaking in the younger age groups up to 30 years (second affected group: 30-40 years). While commonly used solid-phase antibody tests (like immunofluorescence) are not suitable to diagnose passed H1N1(09) infection and acquired immunity, this can be easily done by HI. Expecting the next waves of influenza A/H1N1v infections, HI testing may avoid vaccinations under special risk of severe or hidden adverse reactions.

Chemoresistance acquisition induces a global shift of expression of aniogenesis-associated genes and increased pro-angogenic activity in neuroblastoma cells

Background

Chemoresistance acquisition may influence cancer cell biology. Here, bioinformatics analysis of gene expression data was used to identify chemoresistance-associated changes in neuroblastoma biology.

Results

Bioinformatics analysis of gene expression data revealed that expression of angiogenesis-associated genes significantly differs between chemosensitive and chemoresistant neuroblastoma cells. A subsequent systematic analysis of a panel of 14 chemosensitive and chemoresistant neuroblastoma cell lines in vitro and in animal experiments indicated a consistent shift to a more pro-angiogenic phenotype in chemoresistant neuroblastoma cells. The molecular mechanims underlying increased pro-angiogenic activity of neuroblastoma cells are individual and differ between the investigated chemoresistant cell lines. Treatment of animals carrying doxorubicin-resistant neuroblastoma xenografts with doxorubicin, a cytotoxic drug known to exert anti-angiogenic activity, resulted in decreased tumour vessel formation and growth indicating chemoresistance-associated enhanced pro-angiogenic activity to be relevant for tumour progression and to represent a potential therapeutic target.

Conclusion

A bioinformatics approach allowed to identify a relevant chemoresistance-associated shift in neuroblastoma cell biology. The chemoresistance-associated enhanced pro-angiogenic activity observed in neuroblastoma cells is relevant for tumour progression and represents a potential therapeutic target.

The impact of treatment with tumour necrosis factor-alpha antagonists on the course of chronic viral infections: a review of the literature

Biologics that antagonize the biological activity of tumour necrosis factor (TNF)-alpha, namely infliximab, etanercept and adalimumab, are increasingly used for treatment of immune-mediated inflammatory diseases, including psoriasis, worldwide. TNF-alpha antagonists are known to increase the risk of reactivation and infection, particularly of infections with intracellular bacteria such as Mycobacterium tuberculosis. More frequently these agents are given to patients with viral infections. Viral hepatitis and human immunodeficiency virus infections are often present in these patients, with a considerable geographical variation. Other concomitant viral infections such as herpes, cytomegalovirus and varicella zoster virus may occur much more frequently than tuberculosis or leprosy. General recommendations about the management related to possible problems associated with anti-TNF-alpha treatment and these viral infections are lacking. This short review will give an overview of the most recent data available on the effects of anti-TNF-alpha therapy on viral infections with a particular focus on patient management and screening recommendations.

Inhibition of murine AIDS by pro-glutathione (GSH) molecules

Antioxidant molecules can be used both to replenish the depletion of reduced glutathione (GSH) occurring during HIV infection, and to inhibit HIV replication. The purpose of this work was to assess the efficacy of two pro-GSH molecules able to cross the cell membrane more easily than GSH. We used an experimental animal model consisting of C57BL/6 mice infected with the LP-BM5 viral complex; the treatments were based on the intramuscular administration of I-152, a pro-drug of N-acetylcysteine and S-acetyl-beta-mercaptoethylamine, and S-acetylglutathione, an acetylated GSH derivative. The results show that I-152, at a concentration of 10.7 times lower than GSH, caused a reduction in lymph node and spleen weights of about 55% when compared to infected animals and an inhibition of about 66% in spleen and lymph node virus content. S-acetylglutathione, at half the concentration of GSH, caused a reduction in lymph node weight of about 17% and in spleen and lymph node virus content of about 70% and 30%, respectively. These results show that the administration of pro-GSH molecules may favorably substitute for the use of GSH as such.

Valproic acid inhibits adhesion of vincristine- and cisplatin-resistant neuroblastoma tumour cells to endothelium

Drug resistance to chemotherapy is often associated with increased malignancy in neuroblastoma (NB). In pursuit of alternative treatments for chemoresistant tumour cells, we tested the response of multidrug-resistant SKNSH and of vincristine (VCR)-, doxorubicin (DOX)-, or cisplatin (CDDP)-resistant UKF-NB-2, UKF-NB-3 or UKF-NB-6 NB tumour cell lines to valproic acid (VPA), a differentiation inducer currently in clinical trials. Drug resistance caused elevated NB adhesion (UKF-NB-2(VCR), UKF-NB-2(DOX), UKF-NB-2(CDDP), UKF-NB-3(VCR), UKF-NB-3(CDDP), UKF-NB-6(VCR), UKF-NB-6(CDDP)) to an endothelial cell monolayer, accompanied by downregulation of the adhesion receptor neural cell adhesion molecule (NCAM). Based on the UKF-NB-3 model, N-myc proteins were enhanced in UKF-NB-3(VCR) and UKF-NB-3(CDDP), compared to the drug naïve controls. p73 was diminished, whereas the p73 isoform deltaNp73 was upregulated in UKF-NB-3(VCR) and UKF-NB-3(CDDP). Valproic acid blocked adhesion of UKF-NB-3(VCR) and UKF-NB-3(CDDP), but not of UKF-NB-3(DOX), and induced the upregulation of NCAM surface expression, NCAM protein content and NCAM coding mRNA. Valproic acid diminished N-myc and enhanced p73 protein level, coupled with downregulation of deltaNp73 in UKF-NB-3(VCR) and UKF-NB-3(CDDP). Valproic acid also reverted enhanced adhesion properties of drug-resistant UKF-NB-2, UKF-NB-6 and SKNSH cells, and therefore may provide an alternative approach to the treatment of drug-resistant NB by blocking invasive processes.

Onconase induces caspase-independent cell death in chemoresistant neuroblastoma cells

The efficacy of Onconase on the growth of a panel of chemosensitive and chemoresistant neuroblastoma cell lines was investigated. Onconase decreased cell viability of chemosensitive (IMR-32, UKF-NB-3) and chemoresistant neuroblastoma cell lines characterised by high expression of P-glycoprotein (P-gp) (UKF-NB-3(r)DOX(20)) or by high P-gp expression in combination with mutated p53 (UKF-NB-3(r)VCR(10), Be(2)-C), in a similar manner. Moreover, Onconase caused cell cycle block in G1 phase and induced caspase-independent cell death. Transmission electron microscope investigations suggested that Onconase-induced autophagy contributes to Onconase-induced cell death. Antitumour activity of Onconase against naïve and drug-resistant neuroblastoma xenografts was confirmed in animals.

Preparation, characterisation and maintenance of drug efficacy of doxorubicin-loaded human serum albumin (HSA) nanoparticles

Human serum albumin (HSA) nanoparticles represent promising drug carrier systems. Binding of cytostatics to HSA nanoparticles may diminish their toxicity, optimise their body distribution and/or may overcome multidrug resistance. In the present study, doxorubicin-loaded HSA nanoparticle preparations were prepared. Doxorubicin was loaded to the HSA nanoparticles either by adsorption to the nanoparticles' surfaces or by incorporation into the particle matrix. Both loading strategies resulted in HSA nanoparticles of a size range between 150nm and 500nm with a loading efficiency of 70-95%. The influence on cell viability of the resulting nanoparticles was investigated in two different neuroblastoma cell lines. The anti-cancer effects of the drug-loaded nanoparticles were increased in comparison to doxorubicin solution. Based on these result a standard protocol for the preparation of doxorubicin-loaded HSA nanoparticles for further antitumoural studies was established.

Pharmacology of intracellular cytosine-arabinoside-5'-triphosphate in malignant cells of pediatric patients with initial or relapsed leukemia and in normal lymphocytes

PURPOSE

The prodrug cytosinearabinoside (ara-C) is widely used in the treatment of acute leukemias. The active drug is the intracellular metabolite cytosine-arabinoside-5'-triphosphate (ara-CTP). The purpose of the present study was to investigate the relation between sensitivity and pharmacokinetic parameters Cmax, t1/2 and AUC of ara-CTP. The obtained results were compared to previous studies.

EXPERIMENTAL DESIGN

Cmax, t1/2 and AUC of ara-CTP were assessed in leukemic cells of 17 pediatric patients with acute lymphoblastic leukemia (ALL) and in 6 lymphoblastic cell lines and compared with normal lymphocytes of 9 healthy donors by high pressure liquid chromatography (HPLC). The sensitivity of the cells against ara-C was determined by the MTT assay.

RESULTS

The intracellular accumulation of ara-CTP was significantly lower in normal lymphocytes (Cmax 47.7-60.9 pmol/10(6) cells) compared to leukemic cell lines (Cmax 11-1128 pmol/10(6) cells) and leukemic cells of our patients (Cmax 85.9-631 pmol/10(6) cells). Similar results were found for the AUC. There was no significant difference between initial and relapsed leukemias in our small cohort. A correlation between sensitivity in terms of IC50 values and the intracellular ara-CTP accumulation was observed in cell lines, but not in leukemic cells and normal lymphocytes from healthy donors.

CONCLUSIONS

Pharmacokinetic parameters varied tremendously in leukemic cells in contrast to normal lymphocytes without a difference in sensitivity. It is worthwhile to compare literature data to assess an optimal dosage of ara-C in pediatric patients.

Will the next human influenza pandemic be caused by the virus of the avian flu A/H5N1? Arguments pro and counter

In 1997, the avian influenza A subtype H5N1 that caused big outbreaks of fowl pest in mass poultry farming had emerged in Hong Kong. Its spread throughout Eurasia had given rise to concerns in terms of the possible imminence of the next human influenza pandemic. In this article, epidemiological and virological arguments supporting or declining this fear are outlined and discussed with regard to viral infectivity and pathogenicity.

Antiviral and immunomodulatory properties of new pro-glutathione (GSH) molecules

Reduced glutathione (GSH) is present in millimolar concentrations in mammalian cells. It is involved in many cellular functions such as detoxification, amino acid transport, production of coenzymes, and the recycling of vitamins E and C. GSH acts as a redox buffer to preserve the reduced intracellular environment. Decreased glutathione levels have been found in numerous diseases such as cancer, viral infections, and immune dysfunctions. Many antioxidant molecules, such as GSH and N-acetylcysteine (NAC), have been demonstrated to inhibit in vitro and in vivo viral replication through different mechanisms of action. Accumulating evidence suggests that intracellular GSH levels in antigen-presenting cells such as macrophages, influence the Th1/Th2 cytokine response pattern, and more precisely, GSH depletion inhibits Th1-associated cytokine production and/or favours Th2 associated responses. It is known that GSH is not transported to most cells and tissues in a free form. Therefore, a number of different approaches have been developed in the last years to circumvent this problem. This review discusses the capacity of some new molecules with potent pro-GSH effects either to exert significant antiviral activity or to augment GSH intracellular content in macrophages to generate and maintain the appropriate Th1/Th2 balance. The observations reported herein show that pro-GSH molecules represent new therapeutic agents to treat antiviral infections and Th2-mediated diseases such as allergic disorders and AIDS.

Anti-cancer effects of bortezomib against chemoresistant neuroblastoma cell lines in vitro and in vivo

The proteasome inhibitor bortezomib (Velcade) was recently approved for the treatment of therapy-refractive multiple myeloma and is under investigation for numerous other types of cancer. A phase I clinical trial in paediatric patients resulted in tolerable toxicity. Since the emergence of chemoresistance represents one of the major drawbacks in cancer therapy, we investigated the influence of bortezomib on multi-drug resistant human neuroblastoma cell lines characterised by P-glycoprotein expression and p53 mutation. Nanomolar concentrations of bortezomib inhibited the cell cycle and induced apoptosis in chemosensitive as well as in chemoresistant cell lines. In vivo growth of chemosensitive and chemoresistant neuroblastoma cell lines was inhibited to a similar extent. In addition, bortezomib inhibited vessel formation in neuroblastoma xenografts. These findings and the favourable toxicity profile of bortezomib in children make it reasonable to further pursue additional development of the drug for the treatment of neuroblastoma and other paediatric solid tumours.

Efficacy of various disinfectants against SARS coronavirus

The recent severe acute respiratory syndrome (SARS) epidemic in Asia and Northern America led to broad use of various types of disinfectant in order to control the public spread of the highly contagious virus. However, only limited data were available to demonstrate their efficacy against SARS coronavirus (SARS-CoV). We therefore investigated eight disinfectants for their activity against SARS-CoV according to prEN 14476. Four hand rubs were tested at 30s (Sterillium, based on 45% iso-propanol, 30% n-propanol and 0.2% mecetronium etilsulphate; Sterillium Rub, based on 80% ethanol; Sterillium Gel, based on 85% ethanol; Sterillium Virugard, based on 95% ethanol). Three surface disinfectants were investigated at 0.5% for 30 min and 60 min (Mikrobac forte, based on benzalkonium chloride and laurylamine; Kohrsolin FF, based on benzalkonium chloride, glutaraldehyde and didecyldimonium chloride; Dismozon pur, based on magnesium monoperphthalate), and one instrument disinfectant was investigated at 4% for 15 min, 3% for 30 min and 2% for 60 min [Korsolex basic, based on glutaraldehyde and (ethylenedioxy)dimethanol]. Three types of organic load were used: 0.3% albumin, 10% fetal calf serum, and 0.3% albumin with 0.3% sheep erythrocytes. Virus titres were determined by a quantitative test (endpoint titration) in 96-well microtitre plates. With all tested preparations, SARS-CoV was inactivated to below the limit of detection (reduction factor mostly > or =4), regardless of the type of organic load. In summary, SARS-CoV can be inactivated quite easily with many commonly used disinfectants.

Increased malignant behavior in neuroblastoma cells with acquired multi-drug resistance does not depend on P-gp expression

Acquisition of P-gp-mediated multidrug-resistance does not always correlate with observed malignant behavior of NB. To characterize alterations accompanying development of multidrug-resistance in NB we established two neuroblastoma cell sublines resistant to vincristine (UKF-NB-3rVCR10) and doxorubicin (UKF-NB-3rDOX20). UKF-NB-3rVCR10 and UKF-NB-3rDOX20 overexpressed functional P-gp and developed an increased malignant phenotype: presented constitutive phosphorylation of AKT, resistance to gamma-irradiation, and had increased survival in serum-free medium. Inhibition of P-gp restored chemosensitivity but did not affect increased survival in serum-free medium and sensitivity to gamma-irradiation. Inhibition of AKT had no influence on chemoresistance but restored sensitivity to serum starvation. Both resistant cell lines acquired additional chromosomal changes. UKF-NB-3rVCR10 cells acquired a missense P53 mutation in exon 5, an increased MYCN amplification, an enhanced adhesion to endothelium, a decreased NCAM expression, a distinctly higher clonogenicity, and an increased in vivo tumorigenicity. We conclude that acquisition of increased malignant behavior in neuroblastoma occurs concomitantly with multidrug-resistance and is P-gp-independent.

Valproic acid induces extracellular signal-regulated kinase 1/2 activation and inhibits apoptosis in endothelial cells

The histone deacetylase (HDAC) inhibitor valproic acid (VPA) was recently shown to inhibit angiogenesis, but displays no toxicity in endothelial cells. Here, we demonstrate that VPA increases extracellular signal-regulated kinase 1/2 (ERK 1/2) phosphorylation in human umbilical vein endothelial cells (HUVEC). The investigation of structurally modified VPA derivatives revealed that the induction of ERK 1/2 phosphorylation is not correlated to HDAC inhibition. PD98059, a pharmacological inhibitor of the mitogen-activated protein kinase kinase 1/2, prevented the VPA-induced ERK 1/2 phosphorylation. In endothelial cells, ERK 1/2 phosphorylation is known to promote cell survival and angiogenesis. Our results showed that VPA-induced ERK 1/2 phosphorylation in turn causes phosphorylation of the antiapoptotic protein Bcl-2 and inhibits serum starvation-induced HUVEC apoptosis and cytochrome c release from the mitochondria. Moreover, the combination of VPA with PD98059 synergistically inhibited angiogenesis in vitro and in vivo.

Multimutated herpes simplex virus g207 is a potent inhibitor of angiogenesis

The mode of the antitumoral activity of multimutated oncolytic herpes simplex virus type 1 G207 has not been fully elucidated yet. Because the antitumoral activity of many drugs involves the inhibition of tumor blood vessel formation, we determined if G207 had an influence on angiogenesis. Monolayers of human umbilical vein endothelial cells and human dermal microvascular endothelial cells, but not human dermal fibroblasts, bronchial epithelial cells, and retinal glial cells, were highly sensitive to the replicative and cytotoxic effects of G207. Moreover, G207 infection caused the destruction of endothelial cell tubes in vitro. In the in vivo Matrigel plug assay in mice, G207 suppressed the formation of perfused vessels. Intratumoral treatment of established human rhabdomyosarcoma xenografts with G207 led to the destruction of tumor vessels and tumor regression. Ultrastructural investigations revealed the presence of viral particles in both tumor and endothelial cells of G207-treated xenografts, but not in adjacent normal tissues. These findings show that G207 may suppress tumor growth, in part, due to inhibition of angiogenesis.

SARS-coronavirus (SARS-CoV) and the safety of a solvent/detergent (S/D) treated immunoglobulin preparation

SARS-coronavirus (SARS-CoV) is a newly emerged, highly pathogenic agent that caused over 8000 human infections with nearly 800 deaths between November 2002 and September 2003. While direct person-to-person transmission via respiratory droplets accounted for most cases, other modes have not been ruled out. SARS-CoV viraemia does not seem to reach high titres, however, it has to be excluded that virus transmission may occur via blood transfusion or application of therapeutic plasma products, e.g. fresh-frozen plasma or single components derived thereof. Manufacturing processes of all plasma derivatives are required to comprise dedicated virus inactivation/removal steps. Treatment with a mixture of solvent and detergent (SD) has successfully been applied to inactivate the most members of the transfusion-relevant viruses without affecting therapeutic properties of the products. The SD treatment irreversibly disrupts the lipid envelope of viruses such as HIV, HBV, HCV, HGV and CMV. In this study we evaluated the manufacturing process of an immunoglobulin preparation (OCTAGAM, manufactured by Octapharma Pharmazeutika Produktionsges.m.b.H., Vienna, Austria) for its capacity to inactivate the SARS-CoV. Our results demonstrate that SARS-CoV was completely inactivated below the limit of detection. This was found to occur within 1 min of SD treatment.

Increased systemic efficacy of aphidicolin encapsulated in liposomes

Aphidicolin, a tetracyclic diterpene antibiotic produced by Cephalosporium aphidicola, is under investigation as anti-cancer drug. Because of its poor solubility in water, it cannot be administered directly in vivo. Systemic application of aphidicolin glycinate or aphidicolin gamma-cyclodextrin complexes resulted in tumour growth inhibition but not in cures. To improve the pharmacokinetics, a liposomal preparation of aphidicolin was developed and tested in neuroblastoma-bearing (UKF-NB-3) mice. The loading capacity of these liposomes was limited. Therefore, 4.5 mg aphidicolin/kg body weight was the maximum aphidicolin dose that could be applied as liposomal preparation in this approach. Comparison of effects on tumour growth exhibited by aphidicolin liposomes (4.5 mg aphidicolin/kg) given for 15 consecutive days to those of gamma-cyclodextrin inclusion complexes (15 mg aphidicolin/kg) revealed comparable tumour growth inhibition, although aphidicolin concentrations were approximately 3-fold lower. This shows that liposomal encapsulation is a promising strategy for the improvement of systemic anti-cancer activity of aphidicolin.

Characterization of drug-resistant neuroblastoma cell lines by comparative genomic hybridization

Three parental neuroblastoma cell lines and nine derived lines resistant to Vincristin, Doxorubicin and Cisplatin, respectively, using CGH were studied. CGH profiles of all three parental cell lines were obtained using DNA from a healthy volunteer as reference DNA. Labeled DNA from each of the drug resistant daughter cell lines and labeled DNA from their parental sensitive cell lines were hybridized to obtain a comparison of gains and losses that accompanied the development of resistance for that particular drug. All three parental cell lines were characterized by typical findings for high risk neuroblastoma: N-myc amplification, gain of 17q, and loss of 1p36.2-36.3. Acquired drug resistance in the neuroblastoma cell lines appeared to be accompanied by a large array of DNA sequence copy number changes. The regions frequently affected in chemo-resistant cell lines included gains of 13q14.1-32, and 7q11.2-31.3, 4 q. Amplifications were seen at 7q 21.1 consistent with MDR1 amplification in UKF-NB-2 VCR, UKF-NB-3 DOXO, UKF-NB-4 VCR, and UKF-NB-4 DOXO, but not in any Cisplatin resistant line. All Cisplatin and Doxorubicin and two Vincristin resistant line (UKF-NB-2 VCR and UKF-NB-4 VCR) had a deletion of part of 19q or the whole 19 chromosome. All lines resistant to Vincristin or Doxorubicin and two Cisplatin resistant lines (UKF-NB-2 CDDP and UKF-NB-4 CDDP) had a deletion of at least part of 17q, UKF-NB-4 DOXO had deletion of the whole chromosome 17. The loss of 17q may cause chemoresistance by deletion of topoisomerase IIalpha gene. Deletion of 19 q in all but one chemo-resistant lines may influence of cytochromes P450 genes which are located on 19q13.2. Also gains of 15q 22, which were detected in UKF-NB-4 VCR, UKF-NB-2 DOXO and UKF-NB-4 DO X O, may affect other cytochromes P450 genes.

Stability and inactivation of SARS coronavirus

The SARS-coronavirus (SARS-CoV) is a newly emerged, highly pathogenic agent that caused over 8,000 human infections with nearly 800 deaths between November 2002 and September 2003. While direct person-to-person transmission via respiratory droplets accounted for most cases, other modes have not been ruled out. Faecal shedding is common and prolonged and has caused an outbreak in Hong Kong. We studied the stability of SARS-CoV under different conditions, both in suspension and dried on surfaces, in comparison with other human-pathogenic viruses, including human coronavirus HCoV-229E. In suspension, HCoV-229E gradually lost its infectivity completely while SARS-CoV retained its infectivity for up to 9 days; in the dried state, survival times were 24 h versus 6 days. Thermal inactivation at 56 degrees C was highly effective in the absence of protein, reducing the virus titre to below detectability; however, the addition of 20% protein exerted a protective effect resulting in residual infectivity. If protein-containing solutions are to be inactivated, heat treatment at 60 degrees C for at least 30 min must be used. Different fixation procedures, e.g. for the preparation of immunofluorescence slides, as well as chemical means of virus inactivation commonly used in hospital and laboratory settings were generally found to be effective. Our investigations confirm that it is possible to care for SARS patients and to conduct laboratory scientific studies on SARS-CoV safely. Nevertheless, the agents tenacity is considerably higher than that of HCoV-229E, and should SARS re-emerge, increased efforts need to be devoted to questions of environmental hygiene.

Valproic acid and interferon-alpha synergistically inhibit neuroblastoma cell growth in vitro and in vivo

Valproic acid (VPA) as a differentiation inducing anti-neoplastic substance is currently tested in solid tumour and leukaemia patients. Previously, we were able to show that the anti-cancer activity of VPA was synergistically increased by interferon-alpha (IFN-alpha) in Be(2)-C neuroblastoma (NB) cells. Now, we studied the effects of VPA in combination with IFN-alpha on two other NB cell lines. UKF-NB-2 and UKF-NB-3 cell growth was synergistically inhibited by VPA and IFN-alpha. Cell cycle investigations revealed massive accumulation of cells in G0/G1-phase after a combined treatment with VPA and IFN-alpha. The VPA-induced accumulation of acetylated histones in NB cell nuclei that indicates inhibition of histone deacetylases was not further enhanced by the combination treatment with IFN-alpha. Most strikingly, VPA plus IFN-alpha synergistically inhibited growth of UKF-NB-3 xenograft tumours in nude mice and induced complete cures in two out of six animals, while single treatment merely inhibited tumour growth. The results of this study together with our previous report strongly encourage the clinical evaluation of VPA and IFN-alpha for NB patients.

Infection of cultured intestinal epithelial cells with severe acute respiratory syndrome coronavirus

To identify a model for the study of intestinal pathogenesis of severe acute respiratory syndrome (SARS) we tested the sensitivity of six human intestinal epithelial cell lines to infection with SARS coronavirus (SARS-CoV). In permissive cell lines, effects of SARS-CoV on cellular gene expression were analysed using high-density oligonucleotide arrays. Caco-2 and CL-14 cell lines were found to be highly permissive to SARS-CoV, due to the presence of angiotensin-converting enzyme 2 as a functional receptor. In both cell lines, SARS-CoV infection deregulated expression of cellular genes which may be important for the intestinal pathogenesis of SARS.

Cytomegalovirus infection blocks apoptosis in cancer cells

Recent pathological findings reveal a higher frequency of human cytomegalovirus (HCMV) in tumor cells from different tumors compared with surrounding tissues. Experimental investigations suggest possible supportive effects of HCMV for tumor development and progression. One HCMV effect on tumor cells is the inhibition of apoptosis, leading to the promotion of tumor cell survival. Decreased sensitivity to treatment-induced tumor cell death is a major reason for failure of anticancer chemotherapy. HCMV infection interferes with both the intrinsic and extrinsic cellular apoptosis pathways. HCMV promotes cell survival signaling influencing the tumor suppressor p53 and its relative p73, and stimulates the antiapoptotic Ras/Raf/MEK/Erk- and PI-3K-signaling pathways. Antiapoptotic effects mediated by HCMV are inhibited by antiviral treatment in cell culture. Therefore, a better understanding of the influence of HCMV infection on tumor cell apoptosis might translate into improved anti-cancer therapy.

Valproic acid inhibits angiogenesis in vitro and in vivo

Valproic acid (VPA) is a widely used antiepileptic agent that is undergoing clinical evaluation for anticancer therapy. We assessed the effects of VPA on angiogenesis in vitro and in vivo. In human umbilical vein endothelial cells, therapeutically relevant concentrations of VPA (0.25 to 1 mM) inhibited proliferation, migration, and tube formation. VPA 1 mM inhibited endothelial cell proliferation by 51 +/- 5%, migration by 86 +/- 11%, and tube formation by 82 +/- 3%. These changes were preceded by the hyperacetylation of histone H4, indicating the inhibition of histone deacetylase (HDAC), and a decreased expression of the endothelial nitric-oxide synthase (eNOS). The inhibition of endothelial cell tube formation by VPA was prevented by addition of the nitric oxide donor (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA NONOate). The anticonvulsive active VPA derivative 2-ethyl-4-methylpentanoic acid, which does not inhibit HDAC, did not affect endothelial cell proliferation, tube formation, or eNOS expression. VPA was also found to inhibit angiogenesis in vivo in the chicken chorioallantoic membrane assay and in a Matrigel plug assay in mice. Embryos from VPA-treated mice showed disturbed vessel formation. These results indicate that therapeutic plasma levels of VPA inhibit angiogenesis by a mechanism involving a decrease in eNOS expression preceded by HDAC inhibition.

Thrombin stimulates IL-6 and IL-8 expression in cytomegalovirus-infected human retinal pigment epithelial cells

Recently, we reported that thrombin specifically stimulates protease-activated receptor-1 (PAR-1) signaling in RPE entailing inhibition of Sp1 dependent HCMV replication. We now studied whether thrombin modulates the expression of the proinflammatory cytokine/chemokines IL-6 and IL-8 in mock- and cytomegalovirus-infected human retinal pigment epithelial cells (RPE). Our data show that thrombin/PAR-1 stimulates IL-6 and IL-8 gene transcription and protein secretion in both mock- and HCMV-infected RPE. Thrombin/PAR-1-mediated signaling stimulated PKC and NF-kappaB-dependent IL-6 and IL-8 gene expression via phosphoinositide 3-kinase and further downstream via p42/44 and p38 MAPKs. Thus, thrombin/PAR-1-mediated IL-6/IL-8 gene expression is uncoupled from Sp1 inhibition and may support proinflammatory pathomechanisms probably involved in hemorrhage/HCMV retinitis progression.

The immunosuppressive drug mycophenolate mofetil impairs the adhesion capacity of gastrointestinal tumour cells

Immunosuppression correlates with the development and recurrence of cancer. Mycophenolate mofetil (MMF) has been shown to reduce adhesion molecule expression and leucocyte recruitment into the donor organ. We have hypothesized that MMF might also prevent receptor-dependent tumour dissemination. Therefore, we have investigated the effects of MMF on tumour cell adhesion to human umbilical vein endothelial cells (HUVEC) and compared them with the effects on T cell-endothelial cell interactions. Influence of MMF on cellular adhesion to HUVEC was analysed using isolated CD4+ and CD8+ T cells, or WiDr colon adenocarcinoma cells as the model tumour. HUVEC receptors ICAM-1, VCAM-1, E-selectin and P-selectin were detected by flow cytometry, Western blot or Northern blot analysis. Binding activity of T cells or WiDr cells in the presence of MMF were measured using immobilized receptor globulin chimeras. MMF potently blocked both T cell and WiDr cell binding to endothelium by 80%. Surface expression of the endothelial cell receptors was reduced by MMF in a dose-dependent manner. E-selectin mRNA was concurrently reduced with a maximum effect at 1 microm. Interestingly, MMF acted differently on T cells and WiDr cells. Maximum efficacy of MMF was reached at 10 and 1 microm, respectively. Furthermore, MMF specifically suppressed T cell attachment to ICAM-1, VCAM-1 and P-selectin. In contrast, MMF prevented WiDr cell attachment to E-selectin. In conclusion, our data reveal distinct effects of MMF on both T cell adhesion and tumour cell adhesion to endothelial cells. This suggests that MMF not only interferes with the invasion of alloactivated T cells, but might also be of value in managing post-transplantation malignancy.