Gerhard P. Schwall

Expression and prognostic relevance of annexin A3 in prostate cancer.

OBJECTIVES By differential quantitative protein expression, it has previously been shown that annexin A3 (ANXA3) expression is associated with prostate cancer. However little is known about the role and biology of ANXA3 in the human prostate. The aim of this study was to thoroughly analyze ANXA3 expression patterns and its potential as a prognostic marker in a large set of benign, preneoplastic, and neoplastic prostate tissue samples. METHODS Immunohistochemistry-based ANXA3 protein expression was analyzed for 1589 prostate cancers as well as smaller subsets of benign epithelium and high-grade prostatic intraepithelial neoplasia (PIN) in a tissue microarray format. RESULTS All samples of benign prostatic epithelium and PIN showed ANXA3 protein expression, with PIN lesions showing a decreased staining intensity compared with benign epithelium (p<0.0001). In cancer, ANXA3 protein expression was essentially reduced, resulting in a negative staining rate of 27.2%, which correlated with increasing pT stage and Gleason score (p<0.0001). ANXA3 status in cancer was shown to be an independent adverse prognostic factor and enabled substratification of the large group of intermediate-risk patients (n=969) into high- and low-risk subgroups. CONCLUSIONS ANXA3 represents a promising candidate tissue marker, and when combined with the standard prognostic parameters, is suggested to provide a more precise prediction of prognosis in the individual patient, therefore harboring the potential to contribute to future patient management.

Breast cancer proteomics reveals correlation between estrogen receptor status and differential phosphorylation of PGRMC1.

IntroductionBreast tumors lacking the estrogen receptor-α (ER-α) have increased incidence of resistance to therapy and poorer clinical prognosis.MethodsWhole tissue sections from 16 cryopreserved breast cancer tumors that were either positive or negative for the ER (eight ER positive and eight ER negative) were differentially analyzed by multiplex imaging of two-dimensional PAGE gels using 54 cm isoelectric focusing. Differentially detected spots of Progesterone Receptor Membrane Component 1 (PGRMC1) were shown to differ in phosphorylation status by differential two dimensional polyacrylamide gel electrophoresis of phosphatase-treated tumor proteins. Site directed mutagenesis was used to create putative phosphorylation site point mutants in PGRMC1. Stable transfectants of these mutants in MCF7 cells were assayed for their survival after oxidative stress, and for AKT kinase phosphorylation. Immune fluorescence using anti-PGRMC1 monoclonal antibody 5G7 was performed on breast cancer tissue microarrays.ResultsProteins significantly differentially abundant between estrogen receptor negative and estrogen receptor positive tumors at the 0.1% level were consistent with published profiles, suggesting an altered keratin pool, and increased inflammation and wound responses in estrogen receptor negative tumors. Two of three spots of PGRMC1 were more abundant in estrogen receptor negative tumors. Phosphatase treatment of breast tumor proteins indicated that the PGRMC1 isoforms differed in their phosphorylation status. Simultaneous mutation of PGRMC1 serine-56 and serine-181 fully abrogated the sensitivity of stably transfected MCF7 breast cancer cells to peroxide-induced cell death. Immune fluorescence revealed that PGRMC1 was primarily expressed in ER-negative basal epithelial cells of mammary ductules. Even in advanced tumors, high levels of ER or PGRMC1 were almost mutually exclusive in individual cells. In five out of five examined ductal in situ breast cancers of comedo type, PGRMC1 was expressed in glucose transporter 1 negative or positive poorly oxygenated cells surrounding the necrotic core, surrounded by a more distal halo of ER-positive cells.ConclusionsPGRMC1 phosphorylation may be involved in the clinical differences that underpin breast tumors of differing ER status.

Annexin A3 in Urine: A Highly Specific Noninvasive Marker for Prostate Cancer Early Detection

PURPOSE In prostate cancer cases the early diagnosis of tumors carrying a high risk of progression is of the utmost importance. There is an urgent clinical need to avoid unnecessary biopsies and subsequent overtreatment. We validated annexin A3 as a diagnostic marker for prostatic disease in typical clinical populations and relevant segments, such as patients with a negative digital rectal examination and low prostate specific antigen. MATERIALS AND METHODS We performed a blinded clinical study (ClinicalTrials.gov Identifier NCT00400894) from September 2005 to January 2007 in 591 patients who were continuously recruited from 4 European urological clinics. Urine was obtained directly after digital rectal examination and the annexin A3 concentration in urine was quantified by Western blot. Statistical analysis included combinations of annexin A3 with total, percent free, complexed and percent complexed prostate specific antigen. RESULTS Combined readouts of prostate specific antigen and urinary annexin A3 were superior to all others with an area under the ROC curve of 0.82 for a total prostate specific antigen range of 2 to 6 ng/ml, 0.83 for a total prostate specific antigen range of 4 to 10 ng/ml and 0.81 in all patients. The best performing prostate specific antigen derivative was percent free prostate specific antigen with an area under the ROC curve of 0.68 for a total prostate specific antigen range of 2 to 6 ng/ml, 0.72 for a total prostate specific antigen range of 4 to 10 ng/ml and 0.73 in all patients. Annexin A3 has an inverse relationship to cancer and, therefore, its specificity was much better than that of prostate specific antigen. CONCLUSIONS Annexin A3 quantification in urine provides a novel noninvasive biomarker with high specificity. Annexin A3 is complementary to prostate specific antigen or to any other cancer marker. It has a huge potential to avoid unnecessary biopsies with a particular strength in the clinically relevant large group of patients who have a negative digital rectal examination and prostate specific antigen in the lower range of values (2 to 10 ng/ml).

Comparative profiling of the mammalian mitochondrial proteome: multiple aconitase-2 isoforms including N-formylkynurenine modifications as part of a protein biomarker signature for reactive oxidative species.

The activity of mitochondria induces, as a byproduct, a variety of post-translational modifications in associated proteins, which have functional downstream consequences for processes such as apoptosis, autophagy, and plasticity; e.g., reactive oxygen species (ROS), which induce N-formyl-kynurenine from oxidized tryptophans in certain mitochondrial proteins which are localized in close spatial proximity to their source. This type of fast molecular changes has profound influence on cell death and survival with implications in a number of pathologies. The quantitative and differential analysis of bovine heart mitochondria by four 2D-PAGE methods, including 2D-PAGE with high-resolution IEF as first dimension, revealed that due to limited resolution, those methods employing blue native-, tricine-urea-, and 16-BAC-PAGE as the first dimension are less applicable for the differential quantitative analysis of redundant protein spots which might give insight into post-translational modifications that are relevant in age- and stress-related changes. Moreover, 2D-PAGE with high resolution IEF was able to resolve a surprisingly large number of membrane proteins from mitochondrial preparations. For aconitase-2, an enzyme playing an important role in mitochondrial aging, a more thorough molecular analysis of all separable isoforms was performed, leading to the identification of two particular N-formylkynurenine modifications. Next to protein redundancy, native protein-protein interactions, with the potential of relating certain post-translational modification patterns to distinct oligomeric states, e.g., oxidative phosphorylation super complexes, might provide novel and (patho-) physiologically relevant information. Among proteins identified, 14 new proteins (GenBank entries), previously not associated with mitochondria, were found.

Systemic administration of neuregulin-1β1 protects dopaminergic neurons in a mouse model of Parkinson’s disease

J. Neurochem. (2011) 117, 1066–1074.

Protein biomarkers for in vitro testing of embryotoxicity.

There are new challenges for hazard and risk assessment in the chemical industry with regard to REACH legislation in Europe and related activities in the U.S. and Japan, which require the development of novel in vitro models for the molecular characterization of drug- or chemical-related effects replacing conventional animal testing. In the frame of a European FP6 project on reproductive toxicology ( www.reprotect.eu ), we prepared protein samples from mouse embryonic stem cells differentiated into contracting cardiomyocytes according to the validated embryonic stem cell test (EST) protocol, which had been exposed to toxic substances selected by an expert committee from different in vivo categories of embryotoxicity. Lysates were used to carry out the following investigations: (i) identify optimal dose range conditions in the EST that are suitable for (ii) performing a differential quantitative proteomic study of underlying molecular pathways, (iii) define classes of substances with similar proteomic response patterns, (iv) relate these classes to the traditional in vivo categories of embryotoxicity with (v) the final goal to identify novel surrogate protein biomarker candidates for embryo toxicity. We found two distinct classes of toxic substances (Dinoseb, Ochratoxin-A, and Nitrofen vs β-aminoproprionitril, Metoclopramide, Doxylamine succinate, and d-penicillamine) with clear pathway-related differences in their proteomic patterns. Most notably, different responses to cluster 1 and cluster 2 substances were observed for Heat shock protein β-1, Ras-GTPase-activating protein SH3-domain binding protein, Ran binding protein 5, and Calreticulin, Dihydropyrimidinase-like 2 (Ulip2 protein). On the other hand, Heat shock protein 8 and Fscn1 protein were down-regulated by all compounds from both clusters.

BACE-1 is expressed in the blood-brain barrier endothelium and is upregulated in a murine model of Alzheimer's disease.

Endothelial cells of the blood–brain barrier form a structural and functional barrier maintaining brain homeostasis via paracellular tight junctions and specific transporters such as P-glycoprotein. The blood–brain barrier is responsible for negligible bioavailability of many neuroprotective drugs. In Alzheimer’s disease, current treatment approaches include inhibitors of BACE-1 (β-site of amyloid precursor protein cleaving enzyme), a proteinase generating neurotoxic β-amyloid. It is known that BACE-1 is highly expressed in endosomes and membranes of neurons and glia. We now provide evidence that BACE-1 is expressed in blood–brain barrier endothelial cells of human, mouse, and bovine origin. We further show its predominant membrane localization by 3D-dSTORM super-resolution microscopy, and by biochemical fractionation that further shows an abluminal distribution of BACE-1 in brain microvessels. We confirm its functionality in processing APP in primary mouse brain endothelial cells. In an Alzheimer’s disease mouse model we show that BACE-1 is upregulated at the blood–brain barrier compared to healthy controls. We therefore suggest a critical role for BACE-1 at the blood–brain barrier in β-amyloid generation and in vascular aspects of Alzheimer’s disease, particularly in the development of cerebral amyloid angiopathy.

A connection between the mitochondrial permeability transition pore, autophagy, and cerebral amyloidogenesis.

In a drug reprofiling attempt, we explored novel neuroprotective properties of 4-azasteroids by synthesizing chemical affinity tags capturing adenine nucleotide translocator-1, as a potential target. Dutasteride inhibits the mitochondrial transition pore and induces an increase of autophagosomal structures in human cell lines. In vivo, a surprising reduction of the beta-amyloid plaque load in a model for cerebral amyloidosis appears to connect release of neurotoxic peptides, mitochondrial apoptosis and autophagy.

Age-dependent posttranslational modifications of voltage-dependent anion channel 1

The accumulation of oxidative damage in mitochondrial proteins, membranes and DNA during ageing is supposed to lead to mitochondrial inactivation, downstream molecular impairments and subsequent decline of biological systems. In a quantitative study investigating the age-related changes of mitochondrial proteins on the level of oxidative posttranslational modifications, we previously found a set of conserved biomarkers across ageing models in five species with consistent oxidative break-up of tryptophan residues and formation of N-formyl kynurenine. In an additional proteomic profiling of a long-living Drosophila mutant overexpressing mitochondrial Hsp22 and controls, we found age-related redundant isoforms of voltage-dependent anion channel 1 (VDAC-1). A re-examination of data from human umbilical vein endothelial cells (with normal and chemically accelerated in vitro ageing), revealed similar age-dependent alterations of voltage-dependent anion channel isoforms. Building on these results, we examined the expression of VDAC-1 in an in vitro model of excitotoxicity. We show that glutamate-induced calcium toxicity in neurons induces changes of voltage-dependent anion channel 1 related to downstream events of mitochondrial apoptosis like poly-ADP-ribosylation.

Prostate cancer biomarker annexin A3 detected in urines obtained following digital rectal examination presents antigenic variability

OBJECTIVES Annexin A3 (ANXA3) is a potential marker for prostate cancer (PCa). We aimed to develop robust immunoassays suitable for quantifying ANXA3 in urine samples obtained following digital rectal examination (DRE) in order to facilitate the diagnostic performance evaluation of this marker. DESIGN AND METHODS Anti-ANXA3 monoclonal antibodies were generated and their epitopes mapped. Two different ANXA3 assay prototypes were established on the VIDAS® automated immunoanalyser and analytical validation was carried out using post-DRE urine samples obtained from patients with PCa (n=23) or benign prostate hyperplasia (n=31). RESULTS The assays had the same capture antibody (TGC44) but different detection antibodies (13A12 or 5C5), recognizing novel distinct epitopes. Both had a lower limit of quantification <1ng/mL and were highly specific for ANXA3, not cross-reacting with other annexins. Interassay imprecision was ≤11% and ≤15% for 13A12 and 5C5 assays, respectively. Surprisingly, a total lack of correlation was observed between ANXA3 levels measured by these two assays in post-DRE urines, indicating detection of distinct antigenic variants. Two freeze-thaw cycles did not affect analyte stability in either assay, whereas a lack of stability of antigenic variants was observed when samples were stored at -80°C for 1month. CONCLUSIONS Two different antigenic variants of ANXA3 are present in post-DRE urines and their clinical significance for diagnosis of prostate cancer should be further investigated. These variants are not stable over time in samples preserved at -80°C. Until this issue is resolved, ANXA3 should only be measured in freshly collected samples.