Karen Bräutigam

An Integrated Clinical-Genomics Approach Identifies a Candidate Multi-Analyte Blood Test for Serous Ovarian Carcinoma

Purpose: Cancer of the ovary confers the worst prognosis among women with gynecologic malignancies, underscoring the need to develop new biomarkers for detection of early disease, particularly those that can be readily monitored in the blood. Experimental Design: We developed an algorithm to identify secreted proteins encoded among ∼22,500 genes on commercial oligonucleotide arrays and applied it to gene expression profiles of 67 stage I to IV serous papillary carcinomas and 9 crudely enriched normal ovarian tissues, to identify putative diagnostic markers. ELISAs were used to validate increased levels of secreted proteins in patient sera encoded by genes with differentially high expression. Results: We identified 275 genes predicted to encode secreted proteins with increased/decreased expression in ovarian cancers (<0.5- or >2-fold, P < 0.001). The serum levels of four of these proteins (matrix metalloproteinase-7, osteopontin, secretory leukoprotease inhibitor, and kallikrein 10) were significantly elevated in a series of 67 independent patients with serous ovarian carcinomas compared with 67 healthy controls (P < 0.001, Wilcoxon rank sum test). Optimized support vector machine classifiers with as few as two of these markers (osteopontin or kallikrein 10/matrix metalloproteinase-7) in combination with CA-125 yielded sensitivity and specificity values ranging from 96% to 98.7% and 99.7% to 100%, respectively, with the ability to discern early-stage disease from normal, healthy controls. Conclusions: Our data suggest that this assay combination warrants further investigation as a multi-analyte diagnostic test for serous ovarian adenocarcinoma.

Progression-free survival in ovarian cancer is reflected in epigenetic DNA methylation profiles.

Objective: Many patients with ovarian cancer disease relapse within 6 months after adjuvant chemotherapy, with a limited prognosis. Epigenetic modifications have been shown to play an important role in tumor development and formation. Therefore, global analysis of DNA methylation patterns might reveal specific CpG sites that correlate with progression-free interval (PFI) after therapy. Methods: Twenty samples of advanced ovarian cancer with a predominantly serous papillary histological subtype were subjected to DNA methylation profiling. Illumina HumanMethylation27 BeadChip technology was used for simultaneous analysis of 27,578 CpG sites in >14,000 genes. Results: Differential DNA methylation of various cytosines correlated with PFI. However, this becomes only significant by classification according to PFI with a cutoff of >28 months. Longer survival was associated with hypomethylation at specific CpG sites (e.g. GREB1, TGIF and TOB1) and hypermethylation in other genes (e.g. TMCO5, PTPRN and GUCY2C). Gene ontology analysis revealed that differentially methylated genes were significantly overrepresented in the categories telomere organization, mesoderm development and immune regulation. Conclusion: Epigenetic modifications at specific CpG sites correlate with PFI in ovarian cancer. Therefore, such analysis might be of prognostic value.

Fatty acid synthase overexpression: target for therapy and reversal of chemoresistance in ovarian cancer

BackgroundFatty acid synthase (FASN) is crucial to de novo long-chain fatty acid synthesis, needed to meet cancer cells’ increased demands for membrane, energy, and protein production.MethodsWe investigated FASN overexpression as a therapeutic and chemosensitization target in ovarian cancer tissue, cell lines, and primary cell cultures. FASN expression at mRNA and protein levels was determined by quantitative real-time polymerase chain reaction and immunoblotting and immunohistochemistry, respectively. FASN inhibition’s impact on cell viability, apoptosis, and fatty acid metabolism was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide assay, cell death detection enzyme-linked immunosorbent assay, immunoblotting, and 18 F-fluoromethylcholine uptake measurement, respectively.ResultsRelative to that in healthy fallopian tube tissue, tumor tissues had 1.8-fold average FASN protein overexpression; cell lines and primary cultures had 11-fold–100-fold mRNA and protein overexpression. In most samples, the FASN inhibitor cerulenin markedly decreased FASN expression and cell viability and induced apoptosis. Unlike concomitant administration, sequential cerulenin/cisplatin treatment reduced cisplatin’s half maximal inhibitory concentration profoundly (up to 54%) in a cisplatin-resistant cell line, suggesting platinum (re)sensitization. Cisplatin-resistant cells displayed lower 18 F-fluoro-methylcholine uptake than did cisplatin-sensitive cells, suggesting that metabolic imaging might help guide therapy.ConclusionsFASN inhibition induced apoptosis in chemosensitive and platinum-resistant ovarian cancer cells and may reverse cisplatin resistance.

Combined treatment with TRAIL and PPARγ ligands overcomes chemoresistance of ovarian cancer cell lines

PurposeOvarian cancer accounts for the highest mortality among all gynecological cancers, mainly due to the fast developing chemoresistance. The death ligand TRAIL induces apoptosis and is able to sensitize tumor cells to cytostatic drugs without affecting physiological tissue. Combined treatment of TRAIL and the antidiabetic acting PPARγ ligands was shown to induce apoptosis synergistically in different ovarian cancer cell lines.MethodsTo investigate feasible TRAIL-dependent inhibition of proliferation and induction of apoptosis in chemoresistant ovarian cancer cell lines, the drug- and TRAIL-sensitive HEY cell line was utilized to develop subclones with selective resistance against cisplatin, etoposide, docetaxel, paclitaxel, gemcitabine and pemetrexed, as well as against TRAIL as control cell line. Expression of the key factors of the TRAIL signaling pathway, TRAIL receptors 1–4, caspase-8, FLIP and XIAP, was analyzed before and after TRAIL treatment by immunoblotting.ResultsCell proliferation experiments showed TRAIL-dependent inhibition that was further increased by combination treatment with the PPARγ ligands. Simultaneous exposure of TRAIL and the PPARγ ligands also resulted in enhanced induction of apoptosis even in partial TRAIL-resistant HEY cell lines. In the parental HEY cell line, additional treatment with the PPARγ ligands led to an increased protein expression of DR5 and a further decline of XIAP expression.ConclusionTherefore, the combinational treatment with TRAIL and PPARγ ligands might be a promising experimental therapy because the PPARγ ligands, especially d15-PGJ2, sensitize drug-resistant ovarian cancer cells to TRAIL-induced apoptosis.

Reduced hemopexin levels in peritoneal fluid of patients with endometriosis

OBJECTIVE To study altered hemopexin concentrations in peritoneal fluid (PF) samples from patients with endometriosis. Recent data implicate a role of altered iron metabolism in endometriosis patients. Hemopexin is the major transport protein for heme. Like iron, heme exposure to the epithelial surface can provoke oxidative stress on the peritoneal epithelium. Therefore, altered hemopexin concentrations and heme scavenging in PF might play a role in the pathophysiology of endometriosis. DESIGN Prospective explorative study. SETTING Academic tertiary care center. PATIENT(S) Eighty symptomatic patients scheduled for laparoscopy for the diagnosis and/or therapy of endometriosis. INTERVENTION(S) Aspiration of PF samples during laparoscopy. MAIN OUTCOME MEASURE(S) Hemopexin and heme concentration in PF. RESULT(S) At laparoscopy, 47 of 80 (58.8%) patients exhibited endometriosis, and 33 (41.2%) were proven disease-free (CO). By means of ELISA significantly lower concentrations of hemopexin in the samples from patients with endometriosis (endometriosis 0.377 ± 0.16 mg/mL) compared with controls (disease-free 0.479 ± 0.20 mg/mL) could be demonstrated. Heme levels in the samples were not significantly different between groups (endometriosis 9.130 ± 6.124 μM and disease-free 9.990 ± 4.485 μM). There was no significant correlation between heme and hemopexin levels (Pearsons correlation coefficient r = -0.146). Demographic data between the groups were comparable. CONCLUSION(S) These data provide further evidence that hemopexin is significantly down-regulated in PF samples from patients with endometriosis compared with controls. This study confirms recent findings in two-dimensional gel electrophoresis demonstrating a down-regulation of hemopexin in PF from patients with endometriosis in a larger series of samples.

Breakpoint characterization of the der(19)t(11;19)(q13;p13) in the ovarian cancer cell line SKOV‐3

About 20% of ovarian carcinomas show alterations of 19p13 and/or 19q13 in the form of added extra material whose origin often is from chromosome 11. Based on earlier spectral karyotype analysis of the ovarian cancer cell line SKOV‐3, which shows an unbalanced translocation der(19)t(11;19), the aim of this study was to determine the precise breakpoints of that derivative chromosome. After rough delimitation of the breakpoints of microdissected derivative chromosomes by array analysis, we designed a matrix of primers spanning 11q13.2 and 19p13.2 detecting multiple amplicons on genomic and cDNA. Sequencing the amplicons, accurate localization of both breakpoints on both chromosomes was possible and we found that exon 14 of HOOK2 from chromosome 19 and exon 2 of ACTN3 from chromosome 11 were fused in the derivative chromosome. The breakpoint in the HOOK2 gene was in an intrinsic triplet of nucleic acids leading to a shift in the ACTN3 reading frame in the derivative chromosome. This frameshift alteration should give rise to an early stop codon causing a loss of function of ACTN3. Signals in two‐dimensional Western blotting exactly match to calculated molecular mass and the isoelectric point of the fusion protein.

Detection and Specific Elimination of EGFR + Ovarian Cancer Cells Using a Near Infrared Photoimmunotheranostic Approach

PurposeTargeted theranostics is an alternative strategy in cancer management that aims to improve cancer detection and treatment simultaneously. This approach combines potent therapeutic and diagnostic agents with the specificity of different cell receptor ligands in one product. The success of antibody drug conjugates (ADCs) in clinical practice has encouraged the development of antibody theranostics conjugates (ATCs). However, the generation of homogeneous and pharmaceutically-acceptable ATCs remains a major challenge. The aim of this study is to detect and eliminate ovarian cancer cells on-demand using an ATC directed to EGFR.MethodsAn ATC with a defined drug-to-antibody ratio was generated by the site-directed conjugation of IRDye®700 to a self-labeling protein (SNAP-tag) fused to an EGFR-specific antibody fragment (scFv-425).ResultsIn vitro and ex vivo imaging showed that the ATC based on scFv-425 is suitable for the highly specific detection of EGFR+ ovarian cancer cell, human tissues and ascites samples. The construct was also able to eliminate EGFR+ cells and human ascites cells with IC50 values of 45–66 nM and 40–90 nM, respectively.ConclusionOur experiments provide a framework to create a versatile technology platform for the development of ATCs for precise detection and treatment of ovarian cancer cells.

Photoimmunotheranostic agents for triple-negative breast cancer diagnosis and therapy that can be activated on demand

Triple-negative breast cancer (TNBC) is a heterogeneous disease in which the tumors do not express estrogen receptor (ER), progesterone receptor (PgR) or human epidermal growth factor receptor 2 (HER2). Classical receptor-targeted therapies such as tamoxifen or trastuzumab are therefore unsuitable and combinations of surgery, chemotherapy and/or radiotherapy are required. Photoimmunotheranostics is a minimally invasive approach in which antibodies deliver nontoxic photosensitizers that emit light to facilitate diagnosis and produce cytotoxic reactive oxygen species to induce apoptosis and/or necrosis in cancer cells. We developed a panel of photoimmunotheranostic agents against three TNBC-associated cell surface antigens. Antibodies against epidermal growth factor receptor (EGFR), epithelial cell adhesion molecule (EpCAM) and chondroitin sulfate proteoglycan 4 (CSPG4) were conjugated to the highly potent near-infrared imaging agent/photosensitizer IRDye®700DX phthalocyanine using SNAP-tag technology achieving clear imaging in both breast cancer cell lines and human biopsies and highly potent phototherapeutic activity with IC50values of 62–165 nM against five different cell lines expressing different levels of EGFR, EpCAM and CSPG4. A combination of all three reagents increased the therapeutic activity against TNBC cells by up to 40%.

Diagnostik und Therapie des Ovarialkarzinoms

ZusammenfassungBedingt durch Chemotherapieresistenz und das Fehlen einer Methode zur Früherkennung hat das Ovarialkarzinom die ungünstigste Prognose unter den gynäkologischen Malignomen. Um die Mortalität zu senken gilt es, Methoden für die Früherkennung und zur Kontrolle des Therapieerfolges zu etablieren. Bildgebende Verfahren haben sich als ungeeignet erwiesen; neue Marker – etwa in Ergänzung zum etablierten Marker CA-125 – könnten sich als prädiktive und prognostische Marker eignen oder gar zur Früherkennung dienen. In den letzten Jahren wurden molekulare Screeningmethoden und anspruchsvolle biostatistische Algorithmen entwickelt, die viele neue Marker hervorgebracht haben. Dadurch besteht die Möglichkeit, Markerkombinationen auf ihre Relevanz zur Erkennung von Frühstadien oder Therapieresistenzen zu untersuchen. Eine Überwindung der Therapieresistenz des Ovarialkarzinoms durch die Entwicklung neuer, zielgerichteter („targeted“) Therapien, die auf der Identifizierung von für bestimmte Medikamente spezifischen Zielproteinen („targets“) beruhen, scheint erreichbar zu sein. Mit molekularen Methoden werden auch in Blutbahn und Knochenmark disseminierte Tumorzellen mit Potenzial zur Metastasierung nachgewiesen. Die Übersichtsarbeit gibt einen Überblick über molekulare Analysemethoden, die zur Identifizierung neuer molekularer Marker geführt haben bzw. schon in Diagnostik und Therapie des Ovarialkarzinoms eingesetzt werden.AbstractOvarian cancer carries the worst prognosis among all gynecological cancers, mainly due to resistance to chemotherapy and the lack of effective screening methods for early stage detection of the disease. Early detection is necessary to reduce the mortality of ovarian cancer. Imaging techniques including transvaginal ultrasound evaluation have not reached this aim and, therefore, novel biomarkers in addition to the well established CA-125 may serve as early detection markers. Over the past years molecular screening methods and challenging biostatistical algorithms have been developed which have identified many novel biomarkers. Thus it is becoming possible to analyze the relevance of combinations of markers for identification of early stages and therapy resistance. Furthermore overcoming chemoresistance of ovarian cancer seems to be achievable by the development of targeted therapies based on the identification of certain drugs for specific targets. With molecular methods disseminated tumor cells with the potential to metastasize can also be detected in blood and bone marrow. This review gives a summary of molecular screening methods which have led to identification of novel molecular markers or are already the basis of clinical diagnostics and therapy of ovarian cancer.

Simultaneous and independent dual site-specific self-labeling of recombinant antibodies

Antibody-based diagnostic and therapeutic reagents armed with effector molecules such as dyes and drugs offer hope in the battle against cancer. Several site-specific conjugation methods have been developed to equip antibodies with such effector molecules, but they tend to be expensive and involve multiple reaction steps. The conjugation of two different effector molecules to a single antibody also remains a major challenge. Here we describe a simple, controlled, and robust method for the dual site-specific conjugation of an antibody with two effector molecules in a single-pot reaction using the self-labeling SNAP and CLIP protein tags. We verified the principle of the method by labeling an epidermal growth factor receptor (EGFR)-specific single-chain antibody fragment (scFv-425) simultaneously with IRDye700 and Alexa-Fluor647. This dual-labeled antibody bound to EGFR+ ovarian cancer cell lines and tissue samples with high specificity, and its phototherapeutic efficacy was confirmed by the selective killing of EGFR+ cells in vitro.