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Ovarian cancers often develop resistance mechanisms against the standard platinum and taxane chemotherapy, which indicates the need for novel therapeutics to improve patient outcome. In vitro assays were performed to assess the effects and mechanism of action of a novel peptide, GAP-107B8, on ovarian cancer cell viability. Xenograft models were used to determine GAP-107B8’s effects on tumour burden in immune-incompetent mice. GAP-107B8 significantly reduced cell viability in ovarian cancer cell lines, although no synergistic effects with carboplatin were observed. This reduction in cell viability was due in part to apoptosis and may involve mechanisms leading to decreased pAKT, but without any change in pPKC levels. In vivo, GAP-107B8 had no effect on ovarian tumour burden, but significantly reduced ascites volume. The findings suggest that GAP-107B8 can reduce some malignant characteristics of cancer cells in vitro and in vivo and should be evaluated further as a potential therapeutic for ovarian cancer.

Ovarian cancers often develop resistance mechanisms against the standard platinum and taxane chemotherapy, which indicates the need for novel therapeutics to improve patient outcome. In vitro assays were performed to assess the effects and mechanism of action of a novel peptide, GAP-107B8, on ovarian cancer cell viability. Xenograft models were used to determine GAP-107B8’s effects on tumour burden in immune-incompetent mice. GAP-107B8 significantly reduced cell viability in ovarian cancer cell lines, although no synergistic effects with carboplatin were observed. This reduction in cell viability was due in part to apoptosis and may involve mechanisms leading to decreased pAKT, but without any change in pPKC levels. In vivo, GAP-107B8 had no effect on ovarian tumour burden, but significantly reduced ascites volume. The findings suggest that GAP-107B8 can reduce some malignant characteristics of cancer cells in vitro and in vivo and should be evaluated further as a potential therapeutic for ovarian cancer.

Ovarian cancers often develop resistance mechanisms against the standard platinum and taxane chemotherapy, which indicates the need for novel therapeutics to improve patient outcome. In vitro assays were performed to assess the effects and mechanism of action of a novel peptide, GAP-107B8, on ovarian cancer cell viability. Xenograft models were used to determine GAP-107B8’s effects on tumour burden in immune-incompetent mice. GAP-107B8 significantly reduced cell viability in ovarian cancer cell lines, although no synergistic effects with carboplatin were observed. This reduction in cell viability was due in part to apoptosis and may involve mechanisms leading to decreased pAKT, but without any change in pPKC levels. In vivo, GAP-107B8 had no effect on ovarian tumour burden, but significantly reduced ascites volume. The findings suggest that GAP-107B8 can reduce some malignant characteristics of cancer cells in vitro and in vivo and should be evaluated further as a potential therapeutic for ovarian cancer.

Das Medulloblastom ist der häufigste, maligne Hirntumor des Kindesalters. In den letzten Jahren ist es gelungen, molekularbiologisch definierte Subgruppen innerhalb dieser Tumorentität zu definieren, die sich durch ein unterschiedliches therapeutisches Ansprechen differenzieren lassen. Es werden vier Gruppen abgegrenzt: Tumore mit Aktivierung des WNT-Signalwegs, des SHH-Signalwegs, sowie der Gruppe 3, die sich vor allem durch eine Myc Amplifikation auszeichnen und Gruppe 4, in der MycN amplifiziert wird. Während Patienten mit SHH- und WNT-Tumoren eher eine günstige Prognose haben, ist der Bedarf an neuen Therapieansätzen für Patienten mit Gruppe 3- und Gruppe 4-Tumoren auf Grund der schlechten Prognose sehr hoch. Die aus einem malignen Pleuraerguss eines Gruppe 3-Medulloblastom Patienten gewonnenen Tumorzellen konnten erfolgreich als permanente Zelllinie etabliert sowie in vitro und in vivo charakterisiert werden. Dieses Tumormodell habe ich in meiner Dissertationsarbeit genutzt um die zytotoxische Wirkung neuer Zytostatika und Inhibitoren Kombinationen auf das Gruppe 3-Medulloblastom in vitro und im Tiermodell zu untersuchen. Bei der Auswahl neuer Therapieansätze galt die Maßgabe, Substanzen zu wählen, die für den klinischen Einsatz geeignet sind, neue gezielte zytostatische Mechanismen aufweisen und bei denen bereits publizierte Vorarbeiten nahelegen, dass diese das ZNS tatsächlich erreichen. In unserem in vitro Modell testeten wir 23 Substanzen und wählten dann die fünf vielversprechendsten für das subkutane Tumormausmodell aus. Als Vergleichsgruppen für das Therapieansprechen wählten wir die Kombination aus Cisplatin und Etoposid, die gerade bei den Patienten mit einem HochrisikoMedulloblastom die Therapie der Wahl ist. Im ersten Tierversuch konnte gezeigt werden, dass Gemcitabin als Monotherapie den gleichen zytotoxischen Therapieeffekt zeigt, wie Cisplatin und Etoposid in Kombination. Deshalb war nun das Ziel eine Substanz zu finden, welche dann in Kombination mit Gemcitabin einen besseres Therapieansprechen als die Standardtherapie zeigt. Bei der Tumorpräparation im initialen Tierversuch fiel auf, dass die Tumoren stark vaskularisiert sind. Nach dieser Beobachtung stellten wir uns die Fragen, ob die Inhibition des Vaskularisierungsvorgangs im Tumor einen additiven zytotoxischen Effekt auf das Tumorwachstum hat. Daraufhin erweiterten wir die Suche nach geeigneten Substanzen für das Gruppe 3-Medulloblastom um Multikinaseinhibitoren, die auch VEGF-Rezeptoren inhibieren. Überraschenderweise konnten wir zeigen das Gemcitabin in Kombination mit verschiedenen VEGF-Rezeptor-Inhibitoren in den Toxizitätsversuchen in vitro eine 10.000 fach niedrigere EC50 hat als die Kombination aus Cisplatin und Etoposid. Auch in den anschließenden Tierversuchen konnten wir zeigen, dass Gemcitabin in Kombination mit Axitinib einen besseren Therapieerfolg bezogen auf das Tumorwachstum zeigt, als die bisherige Standardtherapie. Darüber hinaus verloren die Tiere, die mit Gemcitabin und Axitinib behandelt wurden deutlich weniger an Gewicht, als die Tiere die die Standardtherapie erhielten. Zusammenfassend können wir zeigen, dass Axitinib, ein neuer pan-VEGF-Rezeptor-Inhibitor der bisher nur in anderen Tumorentitäten wie dem Nierenzellkarzinom zum Einsatz kommt, in Kombination mit Gemcitabin, einem Nukleosidanalogon, einen deutlichen zytotoxischen Effekt an Medulloblastom Zelllinien in vitro als auch im subkutanen und orthotopen Tiermodell hat. Diese Ergebnisse könnten die Basis sein für neue therapeutische Strategien gegen das Gruppe 3-Medulloblastom bei Kindern, die die bisherige Therapie nicht mehr tolerieren oder bereits irreversible Nebenwirkungen der Standardtherapie entwickelt haben / Medulloblastoma is the most common malignant brain tumor in childhood. In the last few years, it could be successfully defined new molecular subgroups within this tumor entity, which also were defined through a different response to therapy. Four groups are delineated: tumors with activation of the WNT signaling pathway, the SHH signaling pathway, group 3, which are mainly characterizied by myc-c amplification and group 4, in which myc-n is amplified. While patients with SHH and WNT tumors tend to have a favorable prognosis, the need for new therapeutic approaches for patients with group 3 and group 4 tumors is very high due to the poor prognosis. ...

Meniscus damage is very common and eventually leads to the deterioration of the entire knee joint. The goal of this study was to provide evidence that supports a proof of concept for a decellularized porcine meniscal xenograft to be used as a treatment method for meniscal injury as a partial or full meniscus transplant. This research adapted an antigen removal protocol for articular cartilage to produce decellularized xenografts in 48% of the time and with no significant difference in DNA content as other current methods. DNA and GAG content, and the compression moduli were significantly lower in the xenograft than the control, but collagen content remained the same. Tensile modulus and ultimate tensile stress were significantly higher for the xenograft than the control. Crosslinking analysis was performed and 0.2% genipin was found to have a significantly higher degree of crosslinking than the rest.

Brain metastases (BM) are the most frequently diagnosed neoplasm to affect the adult central nervous system (CNS), occurring in 20-40% of all cancer patients throughout the course of the disease. The significant advancements to the treatment and control of primary cancers have unfortunately resulted in an increased incidence of BM, however, this complication of cancer progression continues to be met with a dismal outcome and limited therapeutic options. There remains a poor understanding of the several cellular hallmarks of BM, encompassing various molecular, genetic and epigenetic changes that underlay the stages of metastasis, which requires the development of clinically relevant models of metastasis. Our group has previously established the existence of a cancer stem cell/tumor initiating population with patient samples of BM, which established the foundation of this thesis. Thus, I postulate that there exists a subpopulation of cancer stem-like cells, termed brain metastasis initiating cells (BMICs), that is responsible for the initiation of BM and is identifiable by an exclusive subset of genes that regulate self-renewal and metastasis. To support this hypothesis, I established novel experimental models of BM by inoculation of BMICs derived from patient samples of lung-to-brain metastases into intracranial (ICr), intracardiac (ICa), and intrathoracic (IT) routes into NOD/SCID mice. ICr injections validated the presence of a tumor initiating cell (TIC) capacity of BMICs in the secondary environment (brain). From ICa injections I was able to recapitulate macro-metastatic growth, whereas with IT injections I was able to capture the complete metastatic process, from primary lung tumor formation to micro-metastasis growth. Utilizing these models, I determined that the STAT3 pathway and genes SPOCK1 and TWIST2 all contribute to the regulation of BM development, where SPOCK1 may pose as a potential BMIC marker. Further interrogation of the metastatic process utilizing the IT model of BM led to the characterization of “pre-metastasis”, a stage where BMIC cells have crossed the blood-brain barrier and employ mechanisms to invade and seed the neural environment, while simultaneously repressing mechanisms of proliferation and cell growth that would indicate tissue colonization. In summation, I propose a shift in the cancer research paradigm to target the metastatic process itself, to prevent the dissemination of primary tumor cells to the brain. I present models of clinically relevant models of human BM that have proved to be reliable as platforms to interrogate the process of BM, providing insight into the stage of pre-metastasis as a novel therapeutic window into BM prevention and possible extension of patient survival. / Thesis / Doctor of Philosophy (PhD)

No description available.

A 9.4 T magnetic resonance imaging (MRI) system was used to evaluate the response of a human tumour xenograft model to radiation therapy. The apparent diffusion coefficient (ADC) and the transverse relaxation time (T2) of human glioblastoma multiforme (GBM) tumour xenografts in NIH-iii nude mice were measured before, and at multiple points after, treatment of the tumours with 200 kVp x-rays. The response was characterized as a function of a number of variables of interest in the clinical treatment of cancer with external beam radiation therapy. Mean tumour ADC and T2 responses after single fractions of radiation were investigated, with measurements being made until 14 days after treatment. Single fraction doses ranged from 50 cGy to 800 cGy. Fractionated treatments were used to deliver 800 cGy in two or three fractions with fraction spacings of 24 or 72 hours. The role of hypoxia on ADC and T2 response was investigated by using an externally-applied, suture-based ligature to induce a state of reduced oxygenation in tumours during treatment, after which ADC and T2 were measured using serial MRI. Finally, tumours were dissected in order to provide insight into possible pathophysiological mechanisms explaining the observed responses. Tissue sections were prepared and reviewed by a pathologist. This work adds to the body of literature describing tumour ADC and T2 response to anticancer therapy, and adds to the understanding of ADC and T2 response to radiation therapy in particular. This works supports that of others suggesting the use of ADC and T2 as potential biomarkers for tumour response to treatment. / Medical Physics

No description available.