New aspects in deriving health-based guidance values for bromate in swimming pool water

Bromate, classified as a EU CLP 1B carcinogen, is a typical by-product of the disinfection of drinking and swimming pool water. The aim of this study was (a) to provide data on the occurrence of bromate in pool water, (b) to re-evaluate the carcinogenic MOA of bromate in the light of existing data, (c) to assess the possible exposure to bromate via swimming pool water and (d) to inform the derivation of cancer risk-related bromate concentrations in swimming pool water. Measurements from monitoring analysis of 229 samples showed bromate concentrations in seawater pools up to 34 mg/L. A comprehensive non-systematic literature search was done and the quality of the studies on genotoxicity and carcinogenicity was assessed by Klimisch criteria (Klimisch et al., Regul Toxicol Pharmacol 25:1–5, 1997) and SciRAP tool (Beronius et al., J Appl Toxicol, 38:1460–1470, 2018) respectively. Benchmark dose (BMD) modeling was performed using the modeling average mode in BMDS 3.1 and PROAST 66.40, 67 and 69 (human cancer BMDL₁₀; EFSA 2017). For exposure assessment, data from a wide range of sources were evaluated for their reliability. Different target groups (infants/toddlers, children and adults) and exposure scenarios (recreational, sport-active swimmers, top athletes) were considered for oral, inhalation and dermal exposure. Exposure was calculated according to the frequency of swimming events and duration in water. For illustration, cancer risk-related bromate concentrations in pool water were calculated for different target groups, taking into account their exposure using the hBMDL₁₀ and a cancer risk of 1 in 100,000. Convincing evidence was obtained from a multitude of studies that bromate induces oxidative DNA damage and acts as a clastogen in vitro and in vivo. Since statistical modeling of the available genotoxicity data is compatible with both linear as well as non-linear dose–response relationships, bromate should be conservatively considered to be a non-threshold carcinogen. BMD modeling with model averaging for renal cancer studies (Kurokawa et al., J Natl. Cancer Inst, 1983 and 1986a; DeAngelo et al., Toxicol Pathol 26:587–594, 1998) resulted in a median hBMDL₁₀ of 0.65 mg bromate/kg body weight (bw) per day. Evaluation of different age and activity groups revealed that top athletes had the highest exposure, followed by sport-active children, sport-active adults, infants and toddlers, children and adults. The predominant route of exposure was oral (73–98%) by swallowing water, followed by the dermal route (2–27%), while the inhalation route was insignificant (< 0.5%). Accepting the same risk level for all population groups resulted in different guidance values due to the large variation in exposure. For example, for an additional risk of 1 in 100,000, the bromate concentrations would range between 0.011 for top athletes, 0.015 for sport-active children and 2.1 mg/L for adults. In conclusion, the present study shows that health risks due to bromate exposure by swimming pool water cannot be excluded and that large differences in risk exist depending on the individual swimming habits and water concentrations.

Genome-wide expression changes induced by bisphenol A, F and S in human stem cell derived hepatocyte-like cells

The debate about possible adverse effects of bisphenol A (BPA) has been ongoing for decades. Bisphenol F (BPF) and S (BPS) have been suggested as “safer” alternatives. In the present study we used hepatocyte-like cells (HLCs) derived from the human embryonic stem cell lines Man12 and H9 to compare the three bisphenol derivatives. Stem cell-derived progenitors were produced using an established system and were exposed to BPA, BPF and BPS for 8 days during their transition to HLCs. Subsequently, we examined cell viability, inhibition of cytochrome P450 (CYP) activity, and genome-wide RNA profiles. Sub-cytotoxic, inhibitory concentrations (IC₅₀) of CYP3A were 20, 9.5 and 25 µM for BPA, BPF and BPS in Man12 derived HLCs, respectively. The corresponding concentrations for H9-derived HLCs were 19, 29 and 31 µM. These IC₅₀ concentrations were used to study global expression changes in this in vitro study and are higher than unconjugated BPA in serum of the general population. A large overlap of up- as well as downregulated genes induced by the three bisphenol derivatives was seen. This is at least 28-fold higher compared to randomly expected gene expression changes. Moreover, highly significant correlations of expression changes induced by the three bisphenol derivatives were obtained in pairwise comparisons. Dysregulated genes were associated with reduced metabolic function, cellular differentiation, embryonic development, cell survival and apoptosis. In conclusion, no major differences in cytochrome inhibitory activities of BPA, BPF and BPS were observed and gene expression changes showed a high degree of similarity.

Abstract P2-05-22: Prognostic significance of nuclear factor kappa B in node-negative breast cancer is most pronounced in luminal B breast cancer

Background: The importance of the cellular as well as the humoral immune system is increasingly recognized in breast cancer. The transcription factor nuclear factor kappa B (NFKB1) plays an important role in immune cell development. We examined the prognostic significance of NFKB1 in node-negative breast cancer.

Methods: Microarray based gene-expression data for NFKB1 (209239_at) were analysed in four previously published cohorts (Mainz, Rotterdam, Transbig, Yu) of node-negative breast cancer patients not treated with adjuvant therapy (n=824). A meta-analysis of previously published cohorts was performed using a random effects model. Intrinsic subtypes were determined using gene-expression data. Prognostic significance of NFKB1 for metastasis-free survival (MFS) was examined in the whole cohort, in estrogen receptor (ER) positive as well as ER negative patients, and in different intrinsic subtypes: luminal A, liminal B, basal-like, HER2-enriched (HER2-E), and normal-like. Independent prognostic relevance was analysed using multivariate Cox regression.

Results: Higher RNA expression of NFKB1 was related to better MFS in a meta-analysis of the whole cohort (HR 0.48, 95% CI 0.34-0.67, P&lt;0.0001). NFKB1 was significantly associated with MFS only in ER positive (HR 0.41, 95% CI 0.24−0.69, P=0.0008) but not in ER negative (HR 0.76, 95% CI 0.39−1.48, P=0.4245) patients. Regarding intrinsic subtypes, the prognostic significance of NFKB1 was most pronounced in luminal B breast cancer (HR 0.40, 95% CI 0.17−0.93, P=0.0338) as compared to luminal A (HR 0.67, 95% CI 0.16−2.73, P=0.5738), basal-like (HR 0.67, 95% CI 0.29−1.56), P=0.3484), HER2-E (HR 0.70, 95% CI 0.25−2.00, P=0.5083), and normal-like (HR 0.49, 95% CI 0.18−1.32, P=0.1579) breast cancer. However, NFKB1 failed to show independent prognostic significance (HR 0.72, 95% CI 0.42-1.24, P=0.235) in multivariate analysis. Only histological grade of differentiation (HR 2.06, 95% CI 1.27-3.35, P=0.003) and tumor size (HR 1.58, 95% CI 1.01-2.48, P=0.045), but neither age nor HER2 status nor hormone receptor status maintained an independent prognostic association with MFS.

Conclusions: The transcription factor NFKB1 shows prognostic significance in node-negative breast cancer. Higher expression of NFKB1 is associated with improved outcome. The prognostic impact of NFKB1 differs between intrinsic subtypes and is most pronounced in luminal B breast cancer.

Citation Format: Schmidt M, Madjar K, Heimes A-S, Battista M, Lebrecht A, Almsetdt K, Hasenburg A, Rahnenführer J, Hengstler JG. Prognostic significance of nuclear factor kappa B in node-negative breast cancer is most pronounced in luminal B breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-22.

Abstract P2-08-07: Prognostic significance of immune checkpoint receptors in node-negative breast cancer

Background: Immune checkpoint blockade is increasingly discussed in breast cancer. We examined the prognostic significance of the immune checkpoint receptors cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death protein 1 (PD-1) in node-negative breast cancer.

Methods: Microarray based gene-expression data for CTLA-4 (221331_x_at) and PD-1 (207634_at) were analysed in four previously published cohorts (Mainz, Rotterdam, Transbig, Yu) of node-negative breast cancer patients not treated with adjuvant therapy (n=824). A meta-analysis of previously published cohorts was performed using a random effects model. Prognostic significance of CTLA-4 as well as PD-1 for metastasis-free survival (MFS) was examined in the whole cohort and in different molecular subtypes: luminal (ER+/HER2-), basal-like (ER-/HER2-) and HER2+. Independent prognostic relevance was analysed using multivariate Cox regression.

Results: Higher RNA expression of CTLA-4 was related to better MFS in a meta-analysis of the whole cohort (HR 0.58, 95% CI 0.38-0.88, P=0.0102). Prognostic significance was most pronounced in the HER2+ positive molecular subtype (HR 0.23, 95% CI 0.08-0.65, P=0.0062) as compared to luminal (HR 0.68, 95% CI 0.39-1.18, P=0.1744) and basal-like (HR 0.53, 95% CI 0.25-1.15), P=0.1087) carcinomas of the breast. PD-1 RNA expression, however, was not associated with outcome in the whole cohort of patients (HR 0.88, 95% CI 0.32-2.43, P=0.1853). A trend for improved survival was noticed in basal-like breast cancer (HR 0.40, 95% CI 0.15-1.08, P=0.0701). Neither luminal (HR 0.81, 95% CI 0.28-2.36, P=0.2122) nor HER2+ (HR 0.85, 95% CI 0.27-2.68, P=0.7759) patients showed an association of PD-1 with MFS. CTLA-4 showed independent prognostic significance (HR 0.393, 95% CI 0.224-0.688, P=0.001) in multivariate analysis. In addition to CTLA-4, only histological grade of differentiation (HR 2.335, 95% CI 1.490-3.660, P&lt;0.0001) and tumor size (HR 1.924, 95% CI 1.260-2.937, P=0.002), but neither PD-1 nor age nor HER2 status nor hormone receptor status retained an independent prognostic association with MFS.

Conclusions: The immune checkpoint receptor CTLA-4 has independent prognostic significance in node-negative breast cancer. Higher expression of CTLA-4 is associated with improved outcome. The prognostic impact of CTLA-4 differs between molecular subtypes and is most pronounced in HER2+ breast cancer.

Citation Format: Schmidt M, van de Sandt L, Heimes A-S, Battista M, Lebrecht A, Almstedt K, Hoffmann G, Rahnenführer J, Hengstler JG. Prognostic significance of immune checkpoint receptors in node-negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-07.

Profiling of drugs and environmental chemicals for functional impairment of neural crest migration in a novel stem cell-based test battery

Developmental toxicity in vitro assays have hitherto been established as stand-alone systems, based on a limited number of toxicants. Within the embryonic stem cell-based novel alternative tests project, we developed a test battery framework that allows inclusion of any developmental toxicity assay and that explores the responses of such test systems to a wide range of drug-like compounds. We selected 28 compounds, including several biologics (e.g., erythropoietin), classical pharmaceuticals (e.g., roflumilast) and also six environmental toxicants. The chemical, toxicological and clinical data of this screen library were compiled. In order to determine a non-cytotoxic concentration range, cytotoxicity data were obtained for all compounds from HEK293 cells and from murine embryonic stem cells. Moreover, an estimate of relevant exposures was provided by literature data mining. To evaluate feasibility of the suggested test framework, we selected a well-characterized assay that evaluates ‘migration inhibition of neural crest cells.’ Screening at the highest non-cytotoxic concentration resulted in 11 hits (e.g., geldanamycin, abiraterone, gefitinib, chlorpromazine, cyproconazole, arsenite). These were confirmed in concentration–response studies. Subsequent pharmacokinetic modeling indicated that triadimefon exerted its effects at concentrations relevant to the in vivo situation, and also interferon-β and polybrominated diphenyl ether showed effects within the same order of magnitude of concentrations that may be reached in humans. In conclusion, the test battery framework can identify compounds that disturb processes relevant for human development and therefore may represent developmental toxicants. The open structure of the strategy allows rich information to be generated on both the underlying library, and on any contributing assay.

Abstract P2-10-13: CD4 positive tumor-infiltrating lymphocytes are associated with improved prognosis in node-negative breast cancer

Background: The prognostic significance of CD8 positive cytotoxic lymphocytes in breast cancer is well accepted. However, the role of CD4 positive lymphocytes is ambiguous. We examined the prognostic relevance of CD4 positive tumor-infiltrating lymphocytes in previously published node-negative breast cancer cohorts using RNA expression.

Methods: Microarray based gene-expression data for CD4 (203547_at) were analyzed in four previously published cohorts (Mainz, Rotterdam, Transbig, Yu) of node-negative breast cancer patients not treated with adjuvant therapy (n = 824). A meta-analysis of previously published cohorts was performed using a random effects model. Prognostic significance of CD4 on metastasis-free survival (MFS) was examined in the whole cohort and in different molecular subtypes (ER+/HER2−, ER−/HER2−, HER2+). Independent prognostic relevance was analyzed using multivariate Cox regression.

Results: Higher RNA expression of CD4 was related to better MFS in a meta-analysis of the whole cohort (HR 0.66, 95% CI 0.49–0.90, p = 0.0074). Prognostic significance was most pronounced in the HER2+ positive molecular subtype (HR 0.32, 95% CI 0.14–0.75, p = 0.0091) as compared to ER+/HER2− (HR 0.62, 95% CI 0.29–1.32, P&gt;0.05) and ER−/HER2− (HR 0.61, 95% CI 0.28–1.35, P&gt;0.05) carcinomas of the breast. CD4 showed independent prognostic significance (HR 0.60, 95% CI 0.37–0.96, p = 0.032) in multivariate analysis. In addition to CD4, only histological grade of differentiation (HR 2.43, 95% CI 1.50–3.94, P &lt; 0.001) and tumor size (HR 1.87, 95% CI 1.19–2.94, p = 0.007), but not age, HER2 status or hormone receptor status retained an independent prognostic association with MFS.

Conclusion: CD4 positive tumor-infiltrating lymphocytes have independent prognostic significance in node-negative breast cancer. A higher expression is associated with improved outcome.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-10-13.

P1-01-13: Prognostic Impact of CD8 in Node-Negative Breast Cancer

Background: Infiltration of cytotoxic T lymphocytes (CTL) is a common feature in breast cancer. We examined the prognostic impact of CD8 positive CTL in formalin-fixed-paraffin-embedded (FFPE) tissue using immunohistochemistry (IHC) in node-negative breast cancer and validated our findings in previously published cohorts using RNA expression.

Methods: CD8 was evaluated in FFPE tissue of 339 medically untreated node-negative breast cancer patients utilizing IHC. Results were validated utilizing microarray based gene-expression data of four cohorts of medically untreated node-negative breast cancer patients (n=824). Impact of CD8 on metastasis-free survival (MFS) was analyzed with univariate and multivariate Cox regression. Meta-analysis of previously published cohorts was performed using a random effects model. Prognostic significance was examined in the whole cohort and in different molecular subtypes (ER+/HER2−, ER−/HER2−, HER2). Correlation between RNA expression and IHC was analyzed according to Spearman.

Results: Immunohistochemical detection of CD8+ CTL was associated with MFS in univariate (hazard ratio [HR] 0.76, 95% confidence interval [95% CI] 0.59−0.98, P=0.037) as well as in multivatiate analysis (HR 0.61, 95% CI 0.46−0.81, P=0.001). Protein levels of CD8 had a good correlation with RNA expression (r=0.488). Higher RNA expression of CD8 was related to better MFS in a meta-analysis of the whole cohort (HR 0.74, 95% CI 0.60−0.90, P=0.0023). However, prognostic significance was confined to ER+/HER2− (HR 0.71, 95% CI 0.51−0.99, P=0.0201) and HER2+ (HR 0.60, 95% CI 0.38−0.97, P=0.037) but not to ER−/HER2− molecular subtypes (HR 0.77, 95% CI 0.52−1.14, P=0.1965).

Conclusion: CD8 positive CTL have independent prognostic significance in node-negative breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-01-13.

Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A

Despite the fact that more than 5000 safety-related studies have been published on bisphenol A (BPA), there seems to be no resolution of the apparently deadlocked controversy as to whether exposure of the general population to BPA causes adverse effects due to its estrogenicity. Therefore, the Advisory Committee of the German Society of Toxicology reviewed the background and cutting-edge topics of this BPA controversy. The current tolerable daily intake value (TDI) of 0.05 mg/kg body weight [bw]/day, derived by the European Food Safety Authority (EFSA), is mainly based on body weight changes in two- and three-generation studies in mice and rats. Recently, these studies and the derivation of the TDI have been criticized. After having carefully considered all arguments, the Committee had to conclude that the criticism was scientifically not justified; moreover, recently published additional data further support the reliability of the two- and three-generation studies demonstrating a lack of estrogen-dependent effects at and below doses on which the current TDI is based. A frequently discussed topic is whether doses below 5 mg/kg bw/day may cause adverse health effects in laboratory animals. Meanwhile, it has become clear that positive results from some explorative studies have not been confirmed in subsequent studies with higher numbers of animals or a priori defined hypotheses. Particularly relevant are some recent studies with negative outcomes that addressed effects of BPA on the brain, behavior, and the prostate in rodents for extrapolation to the human situation. The Committee came to the conclusion that rodent data can well be used as a basis for human risk evaluation. Currently published conjectures that rats are insensitive to estrogens compared to humans can be refuted. Data from toxicokinetics studies show that the half-life of BPA in adult human subjects is less than 2 hours and BPA is completely recovered in urine as BPA-conjugates. Tissue deconjugation of BPA-glucuronide and -sulfate may occur. Because of the extremely low quantities, it is only of minor relevance for BPA toxicity. Biomonitoring studies have been used to estimate human BPA exposure and show that the daily intake of BPA is far below the TDI for the general population. Further topics addressed in this article include reasons why some studies on BPA are not reproducible; the relevance of oral versus non-oral exposure routes; the degree to which newborns are at higher systemic BPA exposure; increased BPA exposure by infusions in intensive care units; mechanisms of action other than estrogen receptor activation; and the current regulatory status in Europe, as well as in the USA, Canada, Japan, New Zealand, and Australia. Overall, the Committee concluded that the current TDI for BPA is adequately justified and that the available evidence indicates that BPA exposure represents no noteworthy risk to the health of the human population, including newborns and babies.

Abstract P3-10-22: Prognostic Significance of Aurora Kinase A Expression in Three Cohorts of Node-Negative Breast Cancer Patients

Background: Aurora kinase A (AURKA) is important for cell cycle progression. Inhibitors that target AURKA are currently in clinical development. We examined the prognostic impact of AURKA in three cohorts of node-negative breast cancer patients without adjuvant systemic therapy (n=766).

Methods: AURKA (probe set ID 204092_s_at) was analysed utilizing microarray based gene-expression data of three independent and previously published cohorts of node-negative breast cancer patients (Mainz, Rotterdam, TRANSBIG). In addition to AURKA, we examined the prognostic impact of age, histological grade, tumor size, estrogen receptor (ER) and HER2. Metastasis-free survival (MFS) was analyzed with univariate and multivariate Cox regression.

Results: AURKA displayed a strong positive correlation with grade (P&lt;0.001), tumor size (P&lt;0.001), HER2 (P&lt;0.001), and a negative correlation with ER (P&lt;0.001), respectively. Patients with higher expression of IGKC showed shorter MFS in the Mainz cohort (HR 1.629, 95% CI 1.243-2.134, P&lt;0.001), Rotterdam cohort (HR 1.567, 95% CI 1.271-1.933, P&lt;0.001), and TRANSBIG cohort (HR 1.331, 95% CI 1.081-1.640, p=0.007), respectively. Accordingly, AURKA was significant in univariate analysis in the whole cohort of patients (HR 1.523, 95% CI 1.343-1.726, P&lt;0.001). Using multivariate Cox regression, only tumor size retained its independent prognostic significance (HR 1.818, 95% CI 1.196-2.765, p=0.005). AURKA (HR 1.221, 95% CI 0.987-1.511, p=0.065) and histological grade (HR 1.551, 95% CI 0.955-2.520, p=0.076) showed only borderline significance for MFS.

Conclusion: AURKA has prognostic relevance in three independent cohorts of node-negative breast cancer patients making it a suitable target for therapy with Aurora kinase inhibitors.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-22.

New prognostic and predictive factors in breast cancer

There are two major questions regarding systemic therapy of breast cancer: Firstly, which patients should be treated, and secondly, how should these patients be treated? Prognostic factors aim to foresee the outcome of patients irrespective of treatment while predictive factors intend to assess the outcome of patients receiving a certain systemic therapy and thus are intimately associated with sensitivity or resistance to therapy. Ideally, a predictive factor is also a therapeutic target as it is the case with estrogen receptor (ER) or HER-2. In order to avoid over- as well as under-treatment, it is advisable to select the appropriate treatment strategy on the basis of a careful risk assessment for each individual patient. Additionally to time-honoured clinicopathological factors additional prognostic factors like urokinase-type plasminogen activator (uPA)/plasminogen activator inhibitor 1 (PAI-1) or multiparameter gene-expression analyses have shown promising results especially in node-negative breast cancer. These multigene profiles offer new insights in breast cancer biology, like the important role of the tumor-associated immune system. ER, HER-2 and potentially newer prognostic factors like epithelial cell adhesion molecule (Ep-CAM) bridge the gap from prognosis to prediction and serve as therapeutic targets. This should allow us to quantify the risk of progression in each individual patient and tailor treatment accordingly, leading to a more personalized treatment recommendation.

P2 receptor-mediated stimulation of the PI3-K/Akt-pathway in vivo

ATP acts as a growth factor as well as a toxic agent by stimulating P2 receptors. The P2 receptor-activated signaling cascades mediating cellular growth and cell survival after injury are only incompletely understood. Therefore, the aim of the present study was to identify the role of the phosphoinositide 3 kinase (PI3-K/Akt) and the mitogen-activated protein kinase/extracellular signal regulated protein kinase (MAPK/ERK) pathways in P2Y receptor-mediated astrogliosis after traumatic injury and after microinfusion of ADP beta S (P2Y(1,12,13) receptor agonist) into the rat nucleus accumbens (NAc). Mechanical damage and even more the concomitant treatment with ADP beta S, enhanced P2Y(1) receptor-expression in the NAc, which could be reduced by pretreatment with the P2X/Y receptor antagonist PPADS. Quantitative Western blot analysis indicated a significant increase in phosphorylated (p)Akt and pERK1/2 2 h after ADP beta S-microinjection. Pretreatment with PPADS or wortmannin abolished the up-regulation of pAkt by injury alone or ADP beta S-treatment. The ADP beta S-enhanced expression of the early apoptosis marker active caspase 3 was reduced by PPADS and PD98059, but not by wortmannin. Multiple immunofluorescence labeling indicated a time-dependent expression of pAkt and pMAPK on astrocytes and neurons and additionally the colocalization of pAkt, pMAPK, and active caspase 3 with the P2Y(1) receptor especially at astrocytes. In conclusion, the data show for the first time the involvement of PI3-K/Akt-pathway in processes of injury-induced astroglial proliferation and anti-apoptosis via activation of P2Y(1) receptors in vivo, suggesting specific roles of P2 receptors in glial cell pathophysiology in neurodegenerative diseases.

Characterization of triple-negative breast cancer utilizing microarray-based gene-expression profiling

e22014

Background: Triple-negative breast cancer (TNBC) is characterized by lack of expression of estrogen receptor (ER), progesterone receptor (PR) and HER-2. This makes it one of the most challenging subgroups for clinical decision-making. Methods: We analyzed gene-expression profiles of 200 node-negative breast cancer patients utilizing the Affymetrix HG-U133A array. After performing an unsupervised hierarchical cluster analysis using 2579 genes selected for variable expression within our dataset, we constructed metagenes for five dominant cluster (basal-like, luminal, proliferation, T-cell, B-cell). The interrelation of the median expression of these metagenes between TNBC and those cancer specimens expressing at least one of those receptors was analysed with the Wilcoxon-Mann-Whitney test. An intrinsic gene list was used to define basal-like breast cancer (BLBC). Sensitivity and specificity of TNBC to correctly classify BLBC was calculated. Metastasis-free survival (MFS) at 5 years was calculated according to Kaplan Meier. Results: Of the 200 node-negative breast cancer patients, 33 (16.5%) were triple-negative and 20 (10%) basal-like. Sensitivity of TNBC to correctly predict BLBC was 100%, specificity was 93.1%. TNBC showed an overexpression of the basal-like metagene (P=7.905e-13), an inverse relation with the luminal metagene (p=1.151e-12) and had higher proliferation and higher expression of T-cell (P=6.316e-5) and B-cell (P=3.551e-6) metagene. A higher expression of the B-cell metagene was associated with longer MFS in both TNBC (P=0.048) and BLBC (P=0.041). Conclusions: Characterization of TNBC reveals marked differences in gene-expression. Overexpression of mRNA transcripts related to the humoral immune system might serve as a protective factor in this particular subgroup.

No significant financial relationships to disclose.

Comparing the growth kinetics of cell populations in two and three dimensions

We study the kinetics of growing cell populations by means of a kinetic Monte Carlo method. By applying the same growth mechanism to a two-dimensional (2D) and a three-dimensional (3D) model, and making direct comparison with experimental studies, we show that both models exhibit similar behavior. Based on this we propose a method for establishment of a mapping between the 2D and 3D results. Additionally, we present an analytic approach to obtain the time evolution, and show in case of the 3D model how synchronization effects can influence the growth kinetics. Finally, we compare the results of our models to experimental data of the growth kinetics of 2D monolayers and 3D NIH3T3 xenografts in mice.

Hepatocyte differentiation of mesenchymal stem cells from human adipose tissue in vitro promotes hepatic integration in vivo

OBJECTIVE

The hepatic integration of human adipose tissue derived mesenchymal stem cells (hAT-MSCs) in vivo with or without prior differentiation to hepatocyte-like cells in vitro was investigated.

METHODS AND RESULTS

Cells, isolated either from peritoneal or subcutaneous adipose tissue, expressed mesenchymal stem cell surface markers and featured multiple lineage differentiation. Under conditions favouring hepatocyte differentiation, hAT-MSCs gained hepatocytic functions in vitro including urea formation, glycogen synthesis, cytochrome P450 enzyme activity, and expression of hepatocyte-specific transcripts of carbamoylphosphate synthetase, albumin and cytochrome P450 type 3A4 (CYP3A4). Transgenic expression of green fluorescent protein emerged upon hepatocyte differentiation when driven by the hepatocyte-specific promoter of the cytosolic phosphoenolpyruvate carboxykinase gene but was constitutive from the ubiquitin gene promoter. Human AT-MSCs were transplanted into livers of immunodeficient Pfp/Rag2-/- mice with or without prior hepatocyte differentiation in vitro. Donor-derived human cells engrafted in the mouse host liver predominantly in the periportal region of the liver lobule. They expressed HepPar1 and albumin, typical features of differentiated human hepatocytes, in the otherwise negative mouse liver background. Engraftment was significantly more efficient using hAT-MSCs pre-differentiated to hepatocyte-like cells in vitro as compared with undifferentiated cells.

CONCLUSIONS

Pre-differentiation of human MSCs from adipose tissue into hepatocyte-like cells in vitro facilitates long term functional hepatic integration in vivo.

Primary rat hepatocytes as in vitro system for gene expression studies: comparison of sandwich, Matrigel and 2D cultures

Recent studies have presented evidence that in vivo obtained gene expression data can be used for carcinogen classification, for instance to differentiate between genotoxic and non-genotoxic carcinogens. However, although primary rat hepatocytes represent a well-established in vitro system for drug metabolism and enzyme induction, they have not yet been systematically optimized for toxicogenomic studies. The latter may be confounded by the fact that cultured hepatocytes show strong spontaneous alterations in gene expression patterns. Therefore, we addressed the following questions: (1) which culture system is optimal, comparing sandwich, Matrigel and 2D cultures, (2) how critical is the impact of culture period on substance-induced alterations in gene expression and (3) do these substance-induced alterations in cultured hepatocytes occur already at in vivo relevant concentrations? For this purpose we analyzed the expression of four genes, namely Abat, Gsk3beta, Myd116 and Sult1a1 that recently have been reported to be influenced by the antihistamine and non-genotoxic carcinogen methapyrilene (MPy). The most reproducible effects of MPy were observed in sandwich cultures. Induction factors of Gsk3beta and Myd116 at 100 microM MPy were 2 and 4 (medians), respectively, whereas expression of Abat and Sult1a1 were inhibited by factors of 7 and 5, respectively. Similar results were observed in hepatocytes maintained for 24 h or 3 weeks in sandwich culture with respect to the influence of MPy on the expression of Abat, Gsk3beta, Myd116 and Sult1a1. To determine whether MPy influences gene expression at in vivo relevant concentrations, 3.5 mg/kg MPy were administered to male Wistar rats intraperitoneally, resulting in plasma concentrations ranging between 1.72 and 0.32 microM 5 and 80 min after injection. Inhibition of Abat and Sult1a1 expression in vitro already occurred at in vivo relevant concentrations of 0.39 microM MPy. Induction of Myd116 was observed at 6.25 microM which is higher but in the same order of magnitude as in vivo relevant concentrations. In conclusion, the presented data strongly suggest that sandwich cultures are most adequate for detection of MPy-induced gene expression alterations and the effect of MPy was detected at in vivo relevant concentrations.

Experiences of a Poison Center Network with Renal Insufficiency in Acetaminophen Overdose: An Analysis of 17 Cases

OBJECTIVE

Renal insufficiency is less common than liver failure in acetaminophen overdose but renal tubular damage occurs even in the absence of hepatotoxicity. Data published on this topic are rare consisting mostly of case reports or reports in a small number of patients. Presently, a larger number of patients with renal insufficiency associated with acetaminophen overdose should be analyzed using a multicenter approach.

STUDY DESIGN

Retrospective analysis of patients with acetaminophen-related nephrotoxicity reported to a poison center network from 1995 to 2003. Renal insufficiency was defined as elevated serum creatinine of more than double of the normal range (>2.4 mg/dL [212 micromol/L]). Patients were classified into 4 groups (A: creatinine 2.4-5.0 mg/dL, B: creatinine>5.0 mg/dL requiring no dialysis, C: creatinine>5.0 mg/dL requiring dialysis, D: creatinine>5.0 mg/dL with fatal outcome).

RESULTS

Seventeen patients were included (8 female, 9 male, average age 31.7 +/- 21.1 yrs) with 6 patients in group A (B: 7, C: 2, D: 2). In 5 patients renal insufficiency occurred without elevation of liver enzymes. Regarding possible risk factors 5 patients concomitantly ingested nephrotoxic substances, 4 presented with dehydration due to vomiting, 4 with chronic excessive dosing (overdose) of acetaminophen, 3 showed pre-existing renal insufficiency, 2 pre-existing liver disease and 2 died with multiple organ failure.

CONCLUSIONS

Renal insufficiency in acetaminophen overdose mostly resolved without dialysis and occurred isolated without hepatotoxicity in less than one-third of the investigated patients. Conditions which might play a role as influencing factors for renal complications included concomitant ingestion of nephrotoxic drugs, dehydration, chronic excessive dosing (overdose) of acetaminophen, pre-existing renal or liver disease and multiple organ failure. Renal function should be monitored in acetaminophen overdose particularly in patients showing the latter comorbidity.

Permissive and suppressive effects of dexamethasone on enzyme induction in hepatocyte co-cultures

1. Steroids are known to act as permissive factors in hepatocytes. This study shows that dexamethasone (DEX) is a permissive factor for induction of CYP2B1/2, CYP3A1, CYP2A1 and probably also CYP2C11 in cultures with primary rat hepatocytes. 2. The induction factor of phenobarbital (PB)-induced formation of 16beta-hydroxytestosterone (OHT), a testosterone biotransformation product predominantly formed by CYP2B1, is increased 18-fold by the addition of 32 nM DEX to the culture medium. Interestingly, higher concentrations of DEX up to 1000 nM led to a concentration-dependent maximally 5-fold decrease (p = 0.002) of phenobarbital-induced 16beta-OHT formation compared with the effect observed with 32 nM DEX. Thus, DEX shows permissive and suppressive effects on enzyme induction depending on the concentration of the glucocorticoid. 3. Qualitatively similar but smaller permissive and suppressive effects of DEX were observed for PB-induced CYP3A1 activity as evidenced by formation of 2beta-, 6beta- and 15beta-OHT. 4. DEX is a permissive factor for induction of CYP2A1 activity by 3-methylcholanthrene (3MC), as evidenced by the formation of 7alpha-OHT. Without addition of DEX, 3MC did not induce formation of 7alpha-OHT, whereas an almost 3-fold induction occurred in the presence of DEX. In contrast to CYP2B and CYP3A, concentrations up to 1000 nM DEX were not suppressive for the induction of CYP2A1. 5. We described recently a technique that allows preparation of cultures from cryopreserved hepatocytes. An almost identical influence of dexamethasone on enzyme induction was observed here in cultures from cryopreserved compared with freshly isolated hepatocytes. 6. Cultures with primary hepatocyte cultures represent a well-established technique for the study of drug-drug interactions. However, a large interlaboratory variation is known. Our study provides evidence that differences in glucocorticoid concentration in the culture medium contribute to this variation.

[Procedures for determining occupational diseases in cases of urological disorders]

According to section sign 202 of the German Social Security Code VII, individuals diagnosed with bladder cancer or renal cell cancer who had been occupationally exposed to carcinogens known to induce cancer in these human tissues must be reported to the statutory accident insurance. In this paper, the course of the administrative procedure, particularly considering the reporting procedure and screening for occupational risk factors by a CD-based tool, developed by the authors, is described.

Role of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) for prognosis in endometrial cancer

BACKGROUND

Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) contribute to the invasiveness of many carcinomas. Here, we studied a possible association between cytosolic uPA and PA-1 concentrations in tumor tissue with prognosis in patients with endometrial cancer.

METHODS

Cytosolic concentrations of uPA and PAI-1 were determined in 69 primary endothelial adenocarcinomas using an enzyme-linked immunoassay (ELISA). A possible influence of uPA and PAI-1 was studied by multivariate Cox regression adjusting for the established clinical prognostic factors FIGO-stage, grading, depth of invasion, diabetes mellitus and age.

RESULTS

Both uPA (p=0.011) and PAI-1 (p=0.003) were associated with relapse free time using the multivariate proportional hazards model. Association with overall survival was less pronounced with p=0.021 for uPA and p=0.358 for PAI-1. Concentrations of PAI-1 increased with FIGO stage (p=0.003) and with histological grading (p=0.005). Both uPA and PAI-1 concentrations were negatively correlated with estrogen and progesterone receptor levels.

CONCLUSION

The combination of high cytosolic concentrations of uPA (>5 ng/mg total protein) and high PAI-1 (>20 ng/mg total protein) may reveal a group of patients with increased risk of progression.

Prognostic impact of MKI67 and MMP1 in node-negative invasive ductal and invasive lobular carcinoma of the breast

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Background: MKI67 and MMP1 mRNA, which might reflect the biological processes of tumor proliferation and matrix degradation, respectively, have been proposed as prognostic marker in invasive carcinoma of the breast. We compared the expression of both genes in invasive lobular versus invasive ductal carcinoma, which represent the most common histological breast cancer subtypes. Methods: MKI67 and MMP1 mRNA expression was determined by microarray analysis of fresh frozen tumor tissue of 118 patients with invasive ductal and 39 patients with invasive lobular carcinoma. We compared the distribution of these markers between both histological subtypes as well as within each subtype between tumors from patients with or without subsequent distant metastasis or local recurrence by two tailed Mann-Whitney test. Results: MKI67 as marker of proliferation and MMP1 as marker of matrix degradation were significantly elevated in invasive ducal versus lobular carcinomas (p = 0.023 and p < 0.0001, respectively). Furthermore, elevation of both markers were significantly associated with the occurrence of metastasis in ductal (p = 0.023 and p = 0.012) but not in lobular carcinomas (p = 0.986 and p = 0.366). In addition, no significant association was found between these markers and development of local recurrence in patients with ductal (p = 0.304 and p = 0.899) or lobular (p = 0.891 and p= 0.153) carcinomas . Conclusions: Our data suggest that differences exist between ductal and lobular carcinoma of the breast regarding both the expression and the prognostic impact of MKI67 and MMP1. Furthermore, the prognostic relevance of proliferation and matrix degradation was more important for the development of distant metastasis than for the development of local recurrence in ductal carcinoma emphasizing differences in the underlying biology of local recurrence and distant metastasis.

No significant financial relationships to disclose.

Edi-3, a new independent prognostic factor in ovarian cancer

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Background: Recently, we have identified for the first time a new putative phosphodiesterase named edi-3 that correlates with tumorigenesis in endometrial cancer. In the present study we analyzed the prognostic relevance of edi-3 in ovarian cancer. Methods: Edi-3 mRNA expression was measured by quantitative RT-PCR (TaqMan) in 62 patients with primary ovarian cancer. All patients signed informed consent, approved by the Clinical Review Board and Ethics Committee of the Medical University Berlin, Charité, Germany. The tumor specimens were collected according to the Tumor Bank Ovarian Cancer standard operating procedures. A validated systematic intraoperative documentation tool was used for the detailed documentation of all surgical procedures. Using the multivariate proportional hazard model we analyzed whether edi-3 predicts survival independent from FIGO-stage, grading, postoperative residual disease and histological type. Results: Edi-3 expression is associated with survival in the univariate Cox model (hazards ratio [HR]: 1.488, 95% confidence interval [CI]: 1.131 - 1.959, P=0.005). Interestingly, edi-3 was also predictive in the multivariate proportional hazard model adjusted for the conventional clinical factors (HR: 1.521, CI: 1.107 - 2.090, P=0.010). Conclusions: Edi-3 is a new independent prognostic factor in primary ovarian cancer with HR=1.5 (P=0.010). Its function, a possible role in inositol phosphate metabolism, will be further explored in a multi-instutional setting.

No significant financial relationships to disclose.

Selective Induction of Human Hepatic Cytochromes P450 2B6 and 3A4 by Metamizole

The pyrazolone drug metamizole is a widely used analgesic. Analysis of liver microsomes from patients treated with metamizole revealed selectively higher expression of cytochromes P450, CYP2B6 and CYP3A4 (3.8- and 2.8-fold, respectively), and 2.9-fold higher bupropion hydroxylase activity compared with untreated subjects. Further investigation of metamizole and various derivatives on different potential target genes in human primary hepatocytes demonstrated time- and concentration-dependent induction by metamizole of CYP2B6 (7.8- and 3.1-fold for mRNA and protein, respectively, at 100 muM) and CYP3A4 (2.4- and 2.9-fold, respectively), whereas other genes (CYP2C9, CYP2C19, CYP2D6, NADPH:cytochrome P450 reductase, ABCB1, constitutive androstane receptor (CAR), pregnane X receptor (PXR)) were not substantially altered. Using reporter gene assays, we show that metamizole is not acting as a direct ligand to either PXR or CAR, suggesting a phenobarbital-like mechanism of induction. These data warrant further studies to elucidate the drug-interaction potential of metamizole, especially in patients with long-term treatment.

Primary mouse hepatocytes for systems biology approaches: a standardized in vitro system for modelling of signal transduction pathways

Complex cellular networks regulate regeneration, detoxification and differentiation of hepatocytes. By combining experimental data with mathematical modelling, systems biology holds great promises to elucidate the key regulatory mechanisms involved and predict targets for efficient intervention. For the generation of high-quality quantitative data suitable for mathematical modelling a standardised in vitro system is essential. Therefore the authors developed standard operating procedures for the preparation and cultivation of primary mouse hepatocytes. To reliably monitor the dynamic induction of signalling pathways, the authors established starvation conditions and evaluated the extent of starvation-associated stress by quantifying several metabolic functions of cultured primary hepatocytes, namely activities of glutathione-S-transferase, glutamine synthetase, CYP3A as well as secretion of lactate and urea into the culture medium. Establishment of constant metabolic activities after an initial decrease compared with freshly isolated hepatocytes showed that the cultured hepatocytes achieve a new equilibrium state that was not affected by our starving conditions. To verify the highly reproducible dynamic activation of signalling pathways in the in vitro system, the authors examined the JAK-STAT, SMAD, PI3 kinase, MAP kinase, NF-kappaB and Wnt/beta-catenin signalling pathways. For the induction of gp130, JAK1 and STAT3 phosphorylation IL6 was used, whereas TGFbeta was applied to activate the phosphorylation of SMAD1, SMAD2 and SMAD3. Both Akt/PKB and ERK1/2 phosphorylation were stimulated by the addition of hepatocyte growth factor. The time-dependent induction of a pool of signalling competent beta-catenin was monitored in response to the inhibition of GSK3beta. To analyse whether phosphorylation is actually leading to transcriptional responses, luciferase reporter gene constructs driven by multiple copies of TGFbeta-responsive motives were applied, demonstrating a dose-dependent increase in luciferase activity. Moreover, the induction of apoptosis by the TNF-like cytokine Fas ligand was studied in the in vitro system. Thus, the mouse hepatocyte in vitro system provides an important basis for the generation of high-quality quantitative data under standardised cell culture conditions that is essential to elucidate critical hepatocellular functions by the systems biology approach.