Melanie Wergin

Estrogen-Related Receptor α Is Critical for the Growth of Estrogen Receptor–Negative Breast Cancer

Expression of estrogen-related receptor alpha (ERRalpha) has recently been shown to carry negative prognostic significance in breast and ovarian cancers. The specific role of this orphan nuclear receptor in tumor growth and progression, however, is yet to be fully understood. The significant homology between estrogen receptor alpha (ERalpha) and ERRalpha initially suggested that these receptors may have similar transcriptional targets. Using the well-characterized ERalpha-positive MCF-7 breast cancer cell line, we sought to gain a genome-wide picture of ERalpha-ERRalpha cross-talk using an unbiased microarray approach. In addition to generating a host of novel ERRalpha target genes, this study yielded the surprising result that most ERRalpha-regulated genes are unrelated to estrogen signaling. The relatively small number of genes regulated by both ERalpha and ERRalpha led us to expand our study to the more aggressive and less clinically treatable ERalpha-negative class of breast cancers. In this setting, we found that ERRalpha expression is required for the basal level of expression of many known and novel ERRalpha target genes. Introduction of a small interfering RNA directed to ERRalpha into the highly aggressive breast carcinoma MDA-MB-231 cell line dramatically reduced the migratory potential of these cells. Although stable knockdown of ERRalpha expression in MDA-MB-231 cells had no effect on in vitro cell proliferation, a significant reduction of tumor growth rate was observed when these cells were implanted as xenografts. Our results confirm a role for ERRalpha in breast cancer growth and highlight it as a potential therapeutic target for estrogen receptor-negative breast cancer.

Oxygenation of spontaneous canine tumors during fractionated radiation therapy.

Background and Purpose:Tumor oxygenation predicts treatment outcome, and reoxygenation is considered important in the efficacy of fractionated radiation therapy. Therefore, the purpose of this study was to document the changes of the oxygenation status in spontaneous canine tumors during fractionated radiation therapy using polarographic needle electrodes.Material and Methods:Tumor oxygen partial pressure (pO2) measurements were performed with the Eppendorf-pO2-Histograph. The measurements were done under general anesthesia, and probe tracks were guided with ultrasound. pO2 was measured before radiation therapy in all dogs. In patients treated with curative intent, measurements were done sequentially up to eight times (total dose: 45–59.5 Gy). Oxygenation status of the palliative patient group was examined before each fraction of radiation therapy up to five times (total dose: 24–30 Gy).Results:15/26 tumors had a pretreatment median pO2 ≤ 10 mmHg. The pO2 values appeared to be quite variable in individual tumors during fractionated radiation therapy. The pO2 of initially hypoxic tumors (pretreatment median pO2 ≤ 10 mmHg) remained unchanged during fractionated radiotherapy, whereas in initially normoxic tumors the pO2 decreased.Conclusion:Hypoxia is common in spontaneous canine tumors, as 57.7% of the recorded values were ≤ 10 mmHg. The data of this study showed that initially hypoxic tumors remained hypoxic, whereas normoxic tumors became more hypoxic.Hintergrund und Ziel:Die Sauerstoffversorgung von Tumoren ist ein wichtiger prognostischer Faktor. Die Reoxygenierung von Tumoren nach Bestrahlung wird als wichtiger Mechanismus bei der fraktionierten Radiotherapie angesehen. Ziel der Studie war es, die Veränderungen in der Oxygenierung von spontan gewachsenen Tumoren des Hundes unter fraktionierter Radiotherapie zu beschreiben.Material und Methodik:Der Sauerstoffpartialdruck (pO2) wurde polarographisch mit dem Eppendorf-pO2-Histographen gemessen. Die Messungen erfolgten unter Vollnarkose und Ultraschallkontrolle. Die pO2-Werte wurden vor der Strahlentherapie gemessen. Bei Hunden mit kurativem Behandlungsschema wurden bis zu acht sequentielle Messungen während der Strahlentherapie durchgeführt (Gesamtdosis: 45–59.5 Gy). Der Oxygenierungsstatus der Tumoren mit palliativem Protokoll wurde vor jeder Fraktion bis zu fünfmal bestimmt (Gesamtdosis: 24–30 Gy).Ergebnisse:15/26 Tumoren hatten vor Beginn der Strahlentherapie einen medianen pO2 ≤ 10 mmHg. Der Verlauf der pO2-Werte während fraktionierter Radiotherapie erschien in individuellen Tumoren ziemlich variabel. Wurden die Tumoren in initial hypoxisch (prätherapeutischer medianer pO2 ≤ 10 mmHg) und normoxisch unterteilt, so zeigte sich, dass die pO2-Werte der hypoxischen Tumoren unverändert blieben, während normoxische Tumoren eine Abnahme des pO2 zeigten.Schlussfolgerung:Hypoxie ist normalerweise in spontanen Tumoren des Hundes messbar, lagen doch fast 60% der gemessenen Werte ≤ 10 mmHg. Die Daten dieser Studie zeigten, dass initial hypoxische Tumoren unter fraktionierter Radiotherapie hypoxisch blieben, während initial normoxische Tumoren vermehrt hypoxisch wurden.

Influence of pretreatment polarographically measured oxygenation levels in spontaneous canine tumors treated with radiation therapy

Background and Purpose:The level of hypoxia in primary tumors has been described to influence response to treatment. The aim of the present study was to investigate the impact of pretreatment oxygen level measurements in spontaneous canine tumors on treatment outcome.Materials and Methods:Data of pretreatment tumor oxygenation status and local tumor response after primary radiation therapy in a group of spontaneously occurring tumors in dogs (n = 52) was collected. Radiation therapy was given with curative (14–17 × 3–3.5 Gy) or palliative intent (3 × 8 Gy or 4–5 × 6 Gy). Progression-free interval and overall survival were correlated to polarographically measured tumor oxygenation status.Results:In the curatively irradiated group, tumors with median pO2 values ≤ 10 mmHg tended to have shorter median progression- free interval compared to better oxygenated tumors (246 vs. 739 days). The same trend could be shown for overall survival (330 vs. 745 days), indicating a cutoff value in this region. In the group treated with lower doses of radiation, the level of oxygen was no longer found to be of prognostic value; however, in this group hemoglobin had a significant impact on outcome.Conclusion:In curatively irradiated spontaneous canine tumors, tumor hypoxia was found to be a prognostic indicator, independent of tumor histologies and volume.Hintergrund und Ziel:Das Ausmaß der Hypoxie in Primärtumoren beeinflusst das Ansprechen auf eine Therapie. Das Ziel der vorliegenden Studie war, den Zusammenhang zwischen dem prätherapeutischen Sauerstoffstatus und Ansprechen auf die Strahlentherapie bei Hunden zu untersuchen.Material und Methodik:Bei Hunden (n = 52) mit spontan auftretenden Tumoren, die entweder einer kurativen (14–17 × 3–3,5 Gy) oder einer palliativen Strahlentherapie (3 × 8 Gy oder 4–5 × 6 Gy) unterzogen wurden, wurde der prätherapeutische Sauerstoffpartialdruck gemessen. Die progressionsfreie Zeit sowie die Gesamtüberlebenszeit nach Therapie wurden mit den polarographisch gemessenen Sauerstoffdaten korreliert (Tabelle 1; Abbildung 1).Ergebnisse:In der kurativ bestrahlten Gruppe konnte gezeigt werden, dass Tumoren mit einem Median der pO2-Messwerte von ≤ 10 mmHg eine kürzere progressionsfreie Zeit (246 vs. 739 Tage) und Gesamtüberlebenszeit hatten als besser oxygenierte Tumoren (330 vs. 745 Tage; Abbildung 2). In der palliativ bestrahlten Tiergruppe konnte dieser Effekt nicht gezeigt werden, jedoch wurde ein Einfluss des Hämoglobins auf das Therapieergebnis offensichtlich (Tabellen 2 bis 4).Schlussfolgerung:Bei kurativ bestrahlten spontan auftretenden Tumoren des Hundes ist die Hypoxie ein von Histologie und Tumorvolumen unabhängiger prognostischer Faktor.

A comprehensive test system to identify suitable antibodies against p53 for immunohistochemical analysis of canine tissues

The tumour suppressor p53 is commonly detected in tissues of companion animals by means of antibodies raised against the human protein. The following three-step procedure was devised to test the suitability of such antibodies for immunohistochemistry on canine tissues. (1) Western blot and immunohistochemical analyses on bacterially expressed recombinant canine protein to assess human-to-canine cross-reactivity. (2) Immunohistochemistry of cultured, UVB-irradiated canine keratinocytes to evaluate suitability for detection of endogenous p53. (3) Immunohistochemistry on tissue arrays to further substantiate suitability of the antibodies on a panel of normal and neoplastic human and canine tissues. Five of six antibodies cross-reacted with recombinant canine p53. Three of these (PAb122, PAb240, CM-1) also immunolabelled stabilized wild type p53 in cell cultures and elicited a consistent, characteristic labelling pattern in a subset of tumours. However, two alternative batches of polyclonal antibody CM-1 failed to detect p53 in cell cultures, while showing a characteristic labelling pattern of a completely different subset of tumours and unspecific labelling of normal tissues. The test system described is well suited to the selection of antibodies for immunohistochemical p53 detection. The results emphasize the need to include appropriate controls, especially for polyclonal antibodies.

Correlation of quantified contrast-enhanced power Doppler ultrasonography with immunofluorescent analysis of microvessel density in spontaneous canine tumours.

Conventionally, tumour vascularity is assessed invasively by immunofluorescent analysis. Quantified contrast-enhanced power Doppler ultrasound has been used to measure tumour angiogenesis non-invasively in humans and experimental animals. The purpose of this study was to correlate quantified contrast-enhanced power Doppler ultrasound with immunofluorescent results in 45 spontaneous canine tumours. With power Doppler, mean vascularity was high in squamous cell carcinomas, moderate in malignant oral melanomas and low in sarcomas. There was high mean vascularity in squamous cell carcinomas and low mean vascularity in sarcomas and malignant oral melanomas. Although Doppler parameters correlated moderately with microvascular density for all tumours (P=0.004, r=0.4), they did not correlate within histology groups. These analyses show that vascularity differs among canine tumour histology groups. However, dependent on the method used, measurement of tumour vascularity can provide different biological information.

Measurements of hypoxia ([18F]‐FMISO, [18F]‐EF5) with positron emission tomography (PET) and perfusion using PET ([15O]‐H2O) and power Doppler ultrasonography in feline fibrosarcomas*

Abstract The aim of this study was to evaluate if hypoxia in feline fibrosarcomas can be detected. This was done using positron emission tomography (PET), two hypoxia tracers and polarographic pO(2) measurements. Of the seven cats included, five received [(18)F]-fluoromisonidazole and two 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl) acetamide. Perfusion was evaluated with [(15)O]-H(2)O (n = 4) and with contrast-enhanced power Doppler ultrasonography (n = 5). Hypoxia was detected in three cats. Polarographic pO(2) measurements did not confirm PET results. In the ultrasonographic evaluation, low vascularity and low perfusion were seen with a peripheral vascular pattern and no perfusion in the centre of the tumour. This was in contrast to the [(15)O]-H(2)O scans, where central perfusion of the tumour was also found. In conclusion, it appears that hypoxia exists in this tumour type. The presence of tumour necrosis and heterogeneous hypoxia patterns in these tumours may explain the found discrepancies between the applied techniques.

Positronen-Emissions-Tomographie: Ein bildgebendes Verfahren auf molekularer Ebene

Die Positronen-Emissions-Tomographie (PET) gehort zu den modernen bildgebenden Diagnostikmethoden der Humanmedizin. In dieser Arbeit werden die physikalischen Grundprinzipien der PET skizziert sowie ein Uberblick uber die drei klinischen Haupteinsatzbereiche Neurologie, Kardiologie und Onkologie gegeben.Weiter wird uber ein Projekt in Zusammenarbeit mit dem PaulScherrer-Institut und dem Universitatsspital Zurich berichtet, bei welchem ein neuer Hypoxietracer an Hunden und Katzen mit Spontantumoren evaluiert wird.Abschliessend wird auf neueste Entwicklungen auf dem Gebiet der PET eingegangen. Schlusselworter: Bildgebende Diagnostik, PositronenEmissions-Tomographie, Tracer, Onkologie, Hypoxie. Positron emission tomography: diagnostic imaging on a molecular level In human medicine positron emission tomography (PET) is a modern diagnostic imaging method. In the present paper we outline the physical principles of PET and give an overview over the main clinic fields where PET is being used, such as neurology, cardiology and oncology. Moreover, we present a current project in veterinary medicine (in collaboration with the Paul Scherrer Institute and the University Hospital Zurich), where a hypoxia tracer is applied to dogs and cats suffering from spontaneous tumors. Finally new developments in the field of PET were discussed.