Imaging precessional motion of the magnetization vector

We report on imaging of three-dimensional precessional orbits of the magnetization vector in a magnetic field by means of a time-resolved vectorial Kerr experiment that measures all three components of the magnetization vector with picosecond resolution. Images of the precessional mode taken with submicrometer spatial resolution reveal that the dynamical excitation in this time regime roughly mirrors the symmetry of the underlying equilibrium spin configuration and that its propagation has a non-wavelike character. These results should form the basis for realistic models of the magnetization dynamics in a largely unexplored but technologically increasingly relevant time scale.

Fourier transform imaging of spin vortex eigenmodes

Thin-circular lithographically defined magnetic elements with a spin vortex configuration are excited with a short perpendicular magnetic field pulse. We report the first images of excited magnetic eigenmodes up to third order, obtained by means of a phase sensitive Fourier transform imaging technique. Both axially symmetric and symmetry breaking azimuthal eigenmodes are observed. We observe strong oscillations of the magnetization in the central part of the magnetic elements. The experimental data are in good agreement with micromagnetic simulations.

Cutaneous plasmablastic lymphoma in an HIV-positive male: an unrecognized cutaneous manifestation

Plasmablastic lymphoma (PBL) is a rare and relatively new entity originally described in HIV-infected individuals. This subset of Epstein-Barr-virus (EBV)-related non-Hodgkin lymphomas is now regarded as a distinct clinicopathological category of AIDS-associated lymphomas occurring preferentially in the oral cavity and showing a poor prognosis. We describe for the first time an EBV-associated PBL with an isolated cutaneous distribution on the lower extremities in an HIV-infected heterosexual male and point to the unique clinical, morphological and immunophenotypic characteristics of this lymphoma. The patient presented with fast growing solid and livid nodules on both legs. The large, blastic tumor cells showed the following immunophenotype: CD138+, CD45+, CD20-, CD10-, CD3-, CD30-, bcl-2-, bcl-6-, LMP-1- and EMA-. The proliferation fraction (Mib-1) was >90%. EBV association was demonstrated by in situ hybridization (EBV-encoded RNAs 1/2). Polymerase-chain-reaction-based DNA analysis demonstrated a clonal IgH rearrangement in the absence of a bcl-2/IgH translocation. PBL in HIV patients may occur not only in the oral cavity, but can probably involve any other organs including the skin.

Aspergillus-PCR in bronchoalveolar lavage for detection of invasive pulmonary aspergillosis in immunocompromised patients

BACKGROUND

Invasive fungal disease (IFD) is a frequent and serious infectious complication in immunocompromised patients. Culture and cytology in bronchoalveolar lavage (BAL) have a high specificity but low sensitivity for the diagnosis of IFD as assessed by histology. Molecular methods are expected to allow a rapid diagnosis of IFD with a high sensitivity. We evaluated the diagnostic accuracy of conventional nested PCR in the bronchoalveolar fluid to diagnose IFD in severely immunocompromised patients.

METHODS

Consecutive immunosuppressed patients undergoing bronchoscopy for suspected pulmonary infection in a tertiary care hospital were included. Patients were classified as having "proven", "probable", "possible", and "no" IFD based on definitions of the European Organization for Research and Treatment of Cancer and National Institute of Allergy and Infectious Diseases (EORTC/NIAID) and on clinical grounds. Conventional nested PCR for aspergillus fumigatus, flavus, niger, glaucus, terreus and tomarrii were applied to 2.5 ml bronchoalveolar fluid.

RESULTS

A total of 191 patients were included. Mean age was 51 y, 61% were male. There were 129 patients with hematological conditions, 26 solid organ transplant recipients, 24 auto-immune disorders, and 12 HIV. According to the EORTC/NIAID classification, there were 53 patients with potential IFD: 3 (2%) had proven, 8 (4%) probable, 42 (22%) possible and 138 (72%) no IFD. A total of 111 (58%) of the patients - 10 (90.9%) proven or probable IFD, 32 (76.2%) possible IFD and 69 (50%) "no" IFD) were on anti-fungal therapy at the time of bronchoscopy. Conventional nested PCR for Aspergillus was positive in 55 cases (28.8%). According to these results, sensitivity, specificity, PPV and NPV for "proven" IFD was 0%, 71%, 0%, 98%, respectively and "probable" IFD was 36%, 72%, 7%, 95%, respectively. In 53 (28%) cases there was a strong clinical suspicion of IFD in the chest-x-ray and/or chest-CT irrespective of the EORTC/NIAID classification. However, from those, only 15 (28%) had a positive conventional nested PCR.

CONCLUSION

In our experience, conventional nested Aspergillus PCR in the BAL seems to be of limited usefulness for detection of invasive fungal disease in immunocompromised patients due to the limited sensitivity and specificity of the method.

Search for oncogenic regulators in an autocrine tumor model using differential display PCR: identification of novel candidate genes including the calcium channel mtrp6

A hemopoietic multistep tumor model, in which IL-3 dependent PB-3c mast cells, following expression of v-H-ras progress in vivo to IL-3 producing autocrine tumors has previously been established. Central for this oncogenic progression is a recessive step, which is reversible by cell fusion and leads to stabilization of IL-3 mRNA with concomitant activation of the autocrine loop. Comparing the IL-3 dependent PB-3c and the IL-3 autocrine V2D1 tumor cells with differential display PCR revealed 12 differentially expressed genes of which eight were upregulated and four downregulated in the tumor. They included four proteases (mouse mast cell protease 2, granzyme B, pepsinogen F and serine protease 1) and two metabolic enzymes (adenine phosphoribosyltransferase and fructose1,6-bisphosphatase). For validation, expression of the identified genes was tested in independent PB-3c precursor clones and their tumor derivatives. Expression of an endogenous retroviral IAP element and three unknown transcripts were consistently upregulated in all tumor lines. In somatic cell hybrids, two of these unknown cDNAs showed a dominant and one a recessive expression pattern. One transcript, expressed in the precursor but downregulated in the tumor cells, was cloned and identified as the murine calcium channel mtrp6.

COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany's Largest Public Health Department (Cologne)

BACKGROUND AND METHODS

Vaccination is currently considered the most successful strategy for combating the SARS-CoV-2 virus. According to short-term clinical trials, protection against infection is estimated to reach up to 95% after complete vaccination (≥14 days after receipt of all recommended COVID-19 vaccine doses). Nevertheless, infections despite vaccination, so-called breakthrough infections, are documented. Even though they are more likely to have a milder or even asymptomatic course, the assessment of further transmission is highly relevant for successful containment. Therefore, we calculated the real-world transmission risk from fully vaccinated patients (vaccination group, VG) to their close contacts (CP) compared with the risk from unvaccinated reference persons matched according to age, sex, and virus type (control group = CG) utilizing data from Cologne's health department.

RESULTS

A total of 357 breakthrough infections occurred among Cologne residents between 27 December 2020 (the date of the first vaccination in Cologne) and 6 August 2021. Of the 979 CPs in VG, 99 (10.1%) became infected. In CG, 303 of 802 CPs (37.8%) became infected. Factors promoting transmission included non-vaccinated status (β = 0.237; p < 0.001), male sex (β = 0.079; p = 0.049), the presence of symptoms (β = -0.125; p = 0.005), and lower cycle threshold value (β = -0.125; p = 0.032). This model explained 14.0% of the variance (corr. R2).

CONCLUSION

The number of transmissions from unvaccinated controls was three times higher than from fully vaccinated patients. These real-world data underscore the importance of vaccination in enabling the relaxation of stringent and restrictive general pandemic control measures.

Effective high-throughput RT-qPCR screening for SARS-CoV-2 infections in children

Systematic SARS-CoV-2 testing is a valuable tool for infection control and surveillance. However, broad application of high sensitive RT-qPCR testing in children is often hampered due to unpleasant sample collection, limited RT-qPCR capacities and high costs. Here, we developed a high-throughput approach ('Lolli-Method') for SARS-CoV-2 detection in children, combining non-invasive sample collection with an RT-qPCR-pool testing strategy. SARS-CoV-2 infections were diagnosed with sensitivities of 100% and 93.9% when viral loads were >106 copies/ml and >103 copies/ml in corresponding Naso-/Oropharyngeal-swabs, respectively. For effective application of the Lolli-Method in schools and daycare facilities, SEIR-modeling indicated a preferred frequency of two tests per week. The developed test strategy was implemented in 3,700 schools and 698 daycare facilities in Germany, screening over 800,000 individuals twice per week. In a period of 3 months, 6,364 pool-RT-qPCRs tested positive (0.64%), ranging from 0.05% to 2.61% per week. Notably, infections correlated with local SARS-CoV-2 incidences and with a school social deprivation index. Moreover, in comparison with the alpha variant, statistical modeling revealed a 36.8% increase for multiple (≥2 children) infections per class following infections with the delta variant. We conclude that the Lolli-Method is a powerful tool for SARS-CoV-2 surveillance and can support infection control in schools and daycare facilities.

Ultrafast generation of magnetic fields in a Schottky diode

For the development of future magnetic data storage technologies, the ultrafast generation of local magnetic fields is essential. Subnanosecond excitation of the magnetic state has so far been achieved by launching current pulses into micro-coils and micro-striplines and by using high-energy electron beams. Local injection of a spin-polarized current through an all-metal junction has been proposed as an efficient method of switching magnetic elements, and experiments seem to confirm this. Spin injection has also been observed in hybrid ferromagnetic-semiconductor structures. Here we introduce a different scheme for the ultrafast generation of local magnetic fields in such a hybrid structure. The basis of our approach is to optically pump a Schottky diode with a focused, approximately 150-fs laser pulse. The laser pulse generates a current across the semiconductor-metal junction, which in turn gives rise to an in-plane magnetic field. This scheme combines the localization of current injection techniques with the speed of current generation at a Schottky barrier. Specific advantages include the ability to rapidly create local fields along any in-plane direction anywhere on the sample, the ability to scan the field over many magnetic elements and the ability to tune the magnitude of the field with the diode bias voltage.

Direct identification of differentially expressed genes by cycle sequencing and cycle labelling using the differential display PCR primers

Differential display PCR (DD-PCR) is an mRNA fingerprinting technique to identify differentially expressed genes by comparative display of arbitrarily amplified cDNA subsets. This attractively simple screening method was, however, followed by a labour intensive multistep identification procedure for DD-PCR products. In this report we demonstrate for the mouse mast cell protease 2 (MMCP-2) and the cytotoxic T-lymphocyte associated gene transcript CTLA-1 a streamlined approach by (i) direct cycle sequencing with the upstream differential display (DD) primer, followed by (ii) the PCR based generation of an antisense northern probe with the downstream anchor primer.

Overcoming resistance in a BRAF V600E-mutant adenocarcinoma of the lung

We report on a patient with an adenocarcinoma of the lung harbouring a BRAF V600E mutation who benefited from combination therapy with dabrafenib-trametinib after developing resistance to vemurafenib. To our knowledge, our report shows, for the first time, that combination therapy with dabrafenib-trametinib can overcome vemurafenib resistance in a BRAF V600E-mutated adenocarcinoma of the lung.

Protocol of the Cologne Corona Surveillance (CoCoS) Study- a prospective population-based cohort study

BACKGROUND

Surveillance strategies are critical to cope with the current SARS-CoV-2 pandemic and to evaluate, as well as adjust government-imposed countermeasures. Incidence estimates are widely based on laboratory confirmed cases reported by health authorities. Prevalence and incidence data of SARS-CoV-2 is still scarce, along with demographic and behavioural factors associated with infection risk.

METHODS

The Cologne Corona Surveillance Study will be conducted in the City of Cologne, which is the fourth-largest city in Germany with a population of approximately 1.1 million. Researchers will apply self-sampling surveillance to a rolling cohort of Cologne residents. Random samples of 6000 Cologne residents 18 years of age and older will be drawn from the registration office. Upon receiving the information and saliva sample kit, participants will be asked to fill out a questionnaire online or via phone, sign written informed consent, and send back written consent, as well as saliva sample. The saliva samples will be tested for SARS-CoV-2 by reverse PCR. The questionnaire will be administered to gather information about personal characteristics such as health status and risks. A second round of testing will take place 6 weeks after the first.

DISCUSSION

Self-administered saliva sampling proved to be a legitimate and feasible alternative to nasopharyngeal swabs taken by health professionals. However, it is unclear whether the targeted response rate of 40% can be achieved and whether the results are representative of the population.

TRIAL REGISTRATION

DRKS.de, German Clinical Trials Register (DRKS), Identifier: DRKS00024046 , Registered on 25 February 2021.

Results of the Cologne Corona surveillance (CoCoS) study - a prospective population-based cohort study: incidence data and potential underestimation of new SARS-CoV-2 adult infections by health authorities

BACKGROUND

Current incidence estimates of SARS-CoV-2 in Germany rely to a large extent on case notifications. However, the large number of mild or asymptomatic infections is likely to result in underestimation. Population-based studies can provide valid estimates of the SARS-CoV-2 incidence and thus support health authorities to monitor the epidemiological situation and to initiate, maintain, strengthen or relax effective countermeasures.

METHODS

This study was conducted in Cologne, Germany. Six-thousand randomly drawn Cologne residents, 18 years of age or older, were contacted by mail in March 2021. Study envelopes contained a kit for self-administered saliva sample and access details to a questionnaire on sociodemographic characteristics, previous positive SARS-CoV-2 RT-qPCR and completed COVID-19 vaccinations. Participants were again invited for a second round in June 2021, while those who declined participation were replaced by additional randomly drawn Cologne residents in order to reach a total of 6000 potential participants again. The saliva samples were sent to the laboratory by mail and tested for SARS-CoV-2 using RT-qPCR. The incidence estimates were adjusted for sensitivity and specificity of the test procedure and compared with the official numbers of new SARS-CoV-2 cases in the adult Cologne population.

RESULTS

The first surveillance round in March 2021 (response rate: 34.08%, N = 2045) showed a SARS-CoV-2 seven-day incidence of 85 cases per 100,000 adult Cologne residents (95% CI: 9 to 319). In the same period, the officially registered cases were 125 per 100,000. The second surveillance round in June 2021 (response rate: 36.53%, N = 2192) showed a seven-day incidence of 27 per 100,000 adult Cologne residents (95% CI: 1 to 142), while the official figures for newly registered SARS-CoV-2 cases in the same period were 15 per 100,000.

CONCLUSIONS

The incidence estimates do not indicate relevant underestimation of new SARS-CoV-2 infections based on case notification. Regular use of the surveillance method developed here may nevertheless complement the efforts of the health authorities to assess the epidemiological situation.

TRIAL REGISTRATION

DRKS.de, German Clinical Trials Register (DRKS), Identifier: DRKS00024046 , Registered on 25 February 2021.

Results of the Cologne Corona Surveillance (CoCoS) study - a cross-sectional study: survey data on risk factors of SARS-CoV-2 infection in adults

BACKGROUND

The personal, environmental, and behavioral risk factors that play an important role in the spread of SARS-CoV-2 are still largely unclear. At the same time, there is limited evidence on the effectiveness of specific countermeasures for SARS-CoV-2. As a first approach to these questions, we use data from the Cologne Corona Surveillance (CoCoS) study, a large cross-sectional study conducted in Cologne, Germany, in June 2021.

METHODS

This study was conducted in Cologne, Germany. Six thousand randomly selected Cologne residents who were 18 years of age or older were invited to participate in this study. Participant information was obtained via an online survey. Previous SARS-CoV-2 infections were recorded using self-reports. Sociodemographic and environmental information such as age, sex, living situation were collected. Potential SARS-CoV-2 risk behaviors were captured (workplace situation, adherence to hygiene regulations, and regular use of public transportation). Adherence to hygiene regulations was surveyed by determining the compliance with the 'AHA'-rules (German acronym that stands for keeping a distance of 1.5 m from fellow citizens, hand disinfection, and wearing a face mask). Binary logistic regression analysis was used to identify risk factors for SARS-CoV-2 infection.

RESULTS

A sample of 2,433 study participants provided information. Comparison of the sample with the general population showed representativeness for most sociodemographic characteristics with a preference for higher level of education in the study sample. Younger age, as well as living with minor children (under 18 years) in the same household were associated with a higher number of self-reported SARS-CoV-2 infections. Adherence to hygiene regulations was associated with fewer self-reported SARS-CoV-2 infections in adults. Gender, size of living space per person, workplace situation (work from home versus working with contact to colleagues/customers), and regular use of public transportation showed no significant association with self-reported SARS-CoV-2 infections in multivariable analysis.

CONCLUSION

The presented results provide initial indications of which sociodemographic and behavioral factors may be associated with SARS-CoV-2 infection. However, the fact that these factors were recorded without exact dates and could have changed accordingly during the pandemic or after infection limits the strength of the results.

TRIAL REGISTRATION

DRKS.de, German Clinical Trials Register (DRKS), Identifier: DRKS00024046, Registered on 25 February 2021.

Dynamic vortex-antivortex interaction in a single cross-tie wall

A fascinating property of micromagnetism comes from the possibility to control the domain and vortex configuration through the sample shape and size. For instance, in a rectangular platelet a configuration containing a stable combination of vortices and an antivortex can be created. Such a single cross-tie wall can be understood as being a coupled micromagnetic system with three static solitons. Here we report on its magnetization dynamics including the vortex-antivortex interactions. The spectrum of eigenmodes is investigated as well as the effect of different vortex core orientations. We show that the vortex dynamics can be used to identify the core configuration, which is not directly accessible to x-ray microscopy because of its limited spatial resolution.

[Primary intraocular lymphoma with unusual clinical presentation and poor outcome]

BACKGROUND

Primary intraocular lymphoma is a distinct subset of primary non-Hodgkin's lymphoma of the CNS. In general, the primary non-Hodgkin's lymphoma of the CNS is rare, accounting for 1 % of all non-Hodgkin's lymphomas and less than 1 % of all intraocular tumors.

HISTORY AND SIGNS

A 70-year-old man was hospitalized in June 2002 because of acute loss of vision on his left eye. A severe vitreous hemorrhage was observed. Ultrasound showed solid subretinal lesions at the posterior fundus. Diagnostic vitreous surgery including a biopsy was performed. An intraocular malignant B-cell lymphoma was determined by immunohistochemistry. General screening revealed no further manifestations of the lymphoma.

THERAPY AND OUTCOME

The patient initially refused any therapy until a painful secondary neovascular glaucoma with complete loss of visual function developed, thus prompting us to perform an enucleation. The following immunohistochemical examination confirmed the initial diagnosis. A chemotherapy with high-dose methotrexate and leucovorin rescue was initiated.

CONCLUSIONS

Primary intraocular lymphoma can present as diffuse uveitis refractory to corticosteroids. Diagnosis can be difficult and is often delayed.

Micromagnetic dissipation, dispersion, and mode conversion in thin permalloy platelets

Micron-sized ferromagnetic Permalloy disks exhibiting an in-plane ferromagnetic vortex structure are excited by a fast rise time perpendicular magnetic field pulse and their modal structure is analyzed. We find azimuthal and axial modes. By a Fourier filtering technique we can separate and analyze the time dependence of individual modes. Analysis of the experimental data demonstrates that the azimuthal modes damp more quickly than the axial modes. We interpret these results as mode conversion from low-frequency azimuthal modes to the fundamental mode which is higher in frequency, i.e., mode-mode coupling in a system with a single Landau-Lifshitz-Gilbert phenomenological damping constant alpha.

Magnetization dynamics of Landau structures: tuning the response of mesoscopic magnetic objects using defects

Magnetic vortex cores are interacting with and can even be annihilated by artificial defects, such as holes. These defects have been fabricated by focused ion beam milling (FIB) into the magnetic domains, domain walls and the center of square-shaped vortices, known as Landau structures. We report the imaging of the magnetization dynamics of Landau structures containing holes by means of x-ray magnetic circular dichroism photo-emission electron microscopy (XMCD-PEEM). Due to the high lateral and temporal resolution of this method, the magnetic excitation spectrum, which is characteristic for the vortex-hole interaction, is investigated in detail. We find that the vortex core as well as domain walls can be trapped by small holes. With the help of micromagnetic simulations we show that the vortex gyrotropic motion frequency is enhanced, whereas the amplitude is significantly reduced in the case of non-centric holes in domain walls.

Public Health benefits by implementing digital symptom diaries for COVID patients from Cologne

Background

High rate of people infected with SARS-CoV-2 and their contacts in Cologne, Germany required innovative tools for notification, monitoring and reporting. The digital tool for COVID19 (DiKoMa) provides self-service symptom diaries allowing (a) the stratification for prioritized telephone contact by the health authority and (b) training a machine learning (ML) model that predicts infections with prevailing dominant variant (PDV) from early symptom profiles (SP).

Methods

Pseudononymized SP covering the first week of diary recordings were included for training (16646 index, 11582 contacts). A balanced random forest (BRF) model was trained to differentiate early predictive symptom patterns of different PDV and contact persons. Model evaluation was performed using sex and age stratified cross validation (CV), the model was validated on SP recorded from days 1 and 6.

Results

From 03/20 to 02/22, 90478 indeces and 75444 contact persons reported symptoms and health status, covering 46% and 42% of all reported cases, respectively. Diaries contained between 1-52 entries (566791, median 2). Daily analysis of entries, prioritized according to age, prevalent co-morbidities and detoriation of symptoms allowed risk adjusted follow up even during phases with high case notification rates. The top 5 predictive factors of the BRF were immunization, cough, dysgeusia and dysnosmia, fatigue, and sniffles to differentiate infection between wildtype, three PDV and contact persons (CV AUC 80.6%, Validation AUC 77.1%).

Conclusions

The use of digital symptom diary surveillance helps to provide appropriate medical support for patients on a large scale. Machine learning shows potential for symptom based risk assessment to differentiate PDV for future outbreaks and can thus become a valuable tool alongside specific laboratory diagnostics.

Key messages

• Digital symptom diaries are a powerful and widely accepted tool to attend COVID19 patients in isolation. They allow risk stratification for follow up and are a low-threshold service.

• Machine learning supports index case identification by symptom analysis and can thus become a valuable tool alongside specific laboratory diagnostics.

Symptom diaries as a digital tool to detect SARS-CoV-2 infections and differentiate between prevalent variants

The COVID-19 pandemic and the high numbers of infected individuals pose major challenges for public health departments. To overcome these challenges, the health department in Cologne has developed a software called DiKoMa. This software offers the possibility to track contact and index persons, but also provides a digital symptom diary. In this work, the question of whether these can also be used for diagnostic purposes will be investigated. Machine learning makes it possible to identify infections based on early symptom profiles and to distinguish between the predominant dominant variants. Focusing on the occurrence of the symptoms in the first week, a decision tree is trained for the differentiation between contact and index persons and the prevailing dominant variants (Wildtype, Alpha, Delta, and Omicron). The model is evaluated, using sex- and age-stratified cross-validation and validated by symptom profiles of the first 6 days. The variants achieve an AUC-ROC from 0.89 for Omicron and 0.6 for Alpha. No significant differences are observed for the results of the validation set (Alpha 0.63 and Omicron 0.87). The evaluation of symptom combinations using artificial intelligence can determine the individual risk for the presence of a COVID-19 infection, allows assignment to virus variants, and can contribute to the management of epidemics and pandemics on a national and international level. It can help to reduce the number of specific tests in times of low labor capacity and could help to early identify new virus variants.

Tumor endothelial interaction, CD44+/CD24- stem cell signature, and prognosis in early-stage breast cancer

503

Background: The effects of tumor-endothelial interaction on global gene expression in breast cancer are not yet well characterized. We hypothesized that gene expression signatures induced by tumor-endothelial interaction might be of clinical relevance. Methods: To this aim we set up an ex vivo co-culture model with human benign and a panel of 6 malignant breast epithelial cells in combination with human venous and microvascular endothelial cells and determined associated gene expression changes with cDNA microarrays. Pretreatment gene expression profiles of 295 early stage breast cancers from the Netherlands Cancer Institute with a median follow up of 12.6 years allowed evaluating in vitro effects in vivo. Results: The most prominent response to co-culture was the induction of a set of “M-phase cell cycle” genes in a subset of breast cancer co-cultures, which were absent in co-cultures with normal breast epithelial cells. While in monoculture tumor cells containing the stem cell like CD44+/CD24- signature showed a lower expression of the “M-phase cell cycle” genes than the CD44-/CD24+ cells, in the co-cultures with CD44+/CD24- cells these genes were induced. Interestingly, these tumor cells co- expressed a set of angiogenic factors such as VEGF, PTN, and FGF12 mRNA at significantly higher levels. In vivo, the expression of the gene set derived from the co-culture was remarkably coherent providing a basis for segregation of tumors into two groups. In a univariate analysis, early stage tumors with high expression levels (n= 137) of “M-phase cell cycle” genes had a significantly lower distant metastasis-free survival (p=1.8e-5) (50 % at 10 years) and overall survival rate (p= 5e-9) (52 % at 10 years) than tumors with low expression levels (n= 158) (metastasis-free survival: 73 %; overall survival: 84 % at 10 years). Conclusions: Our results suggest that the interaction of tumor cells expressing the CD44+/CD24- stem cell like signature, implicating a low proliferative potential, with endothelial cells might explain the unexpected and paradoxical association of the CD44+/CD24- signature with highly proliferative tumors with an unfavorable prognosis. Multiple co-expressed angiogenic factors represent potentially interesting additional therapeutic targets.

No significant financial relationships to disclose.

Effects of tumor stroma interaction on global gene expression in breast cancer

10006

Background: Perturbations in cell-cell interaction are a key feature of cancer. However, the systematic effects of cell-cell interaction on global gene expression in cancer are largely unexplored. We hypothesized that gene expression signatures induced by cell-cell interaction might be of clinical relevance. Methods: We simulated tumor-stroma interaction in vitro by systematically co-cultivating each of 7 different breast cancer cell lines with stromal fibroblasts from 3 different sites, and determined associated gene expression changes with cDNA microarrays. A dataset of pretreatment gene expression profiles from 295 early stage breast cancers (stage 1 and 2) with a median follow up of 12.6 years allowed us to evaluate the prognostic significance of the gene expression signatures of specific cell-cell interactions derived from our ex vivo models. Results: The most prominent response to epithelial-mesenchymal interaction was an induction of interferon-response genes (IRG), observed in 4 of the 7 breast cancer cell lines in co-culture with fibroblasts, but not in normal mammary epithelial cells. In response to close contact with these breast cancer cells, the fibroblasts secreted type I interferons, which, in turn, induced expression of the IRG in the tumor cells. Immunohistochemical analysis of human breast cancer tissues showed that Stat1, the key transcriptional activator of the IRG, and itself an IRG, was expressed in a subset of the cancers, with a striking pattern of elevated expression in the cancer cells in contact with, or close proximity to, the tumor stroma - paralleling the response seen in our ex vivo model. In vivo, expression of the IRGs was remarkably coherent, providing a basis for segregation of the 295 early-stage breast cancers into two groups by unsupervised hierarchical clustering with the IRG. Tumors with high expression levels (n=161) of IRG were associated with significantly shorter overall survival; 59% at 10 years versus 80% at 10 years for tumors with low expression levels (n=134) (log-rank p=0.001). Conclusions: Our results suggest that an interaction between some breast cancer cells and stromal fibroblasts can induce an interferon response, and that this response may be associated with a greater propensity for tumor progression.

No significant financial relationships to disclose.