No description available.

Colorectal carcinoma arises through sequential genetic changes whereby an adenoma develops from normal colonic epithelium and then becomes a carcinoma. Critical to this process is two forms of mutually exclusive genomic instability ?? chromosomal instability (CIN) and microsatellite instability (MSI). The colorectal tumours that develop from each of these pathways have distinct pathological and molecular differences. Most MSI+ colorectal carcinomas are associated with the CpG island methylator phenotype (CIMP) - an epigenetic phenomenon where a specific and consistent group of genes are silenced through promoter methylation. However, over half of fall CIMP+ colorectal tumours are microsatellite stable (MSS). It is well known that the WNT/β-catenin signalling pathway is instrumental in the initiation and development of CIN type tumours but it is less clear whether this pathway has any significant involvement in MSI+ or methylated tumours. The role of the PI3K1AKT signalling pathway in the development of solid human tumours has only recently been established and the affects of abnormal PI3K/AKT signalling in sporadic colorectal carcinomas is yet to be fully elucidated. The objective of this thesis was to investigate the involvement of the WNT/β-catenin and PI3K/AKT signalling pathways in the CIN, MSI+ and methylated subgroups of sporadic colorectal carcinoma. To achieve this, the expression patterns of β-catenin, p-AKT and PTEN were identified by immunohistochemistry on sections from tissue microarrays consisting of cores from a large group of sporadic colorectal carcinomas. Each of these proteins is an integral part of the constitutive activation of WNT/β-catenin or PI3K/AKT signalling and their expression patterns were correlated with the clinical, pathological and molecular characteristics of the different subgroups of colorectal carcinoma. Increased nuclear β-catenin expression, an indicator of activated WNT signalling, is associated with MSS and the pathological features of CIN type tumours and inversely associated with the pathological and molecular features of MSI+ and CIMP+ tumours. In all forms of sporadic colorectal carcinoma, nuclear β-catenin expression was not an indicator of overall survival. PTEN was not associated with any particular subgroup of sporadic colorectal carcinoma, but decreased cytoplasmic expression was indicative of overall worse outcome, especially in MSS or CIN type tumours. While the identification of nuclear β-catenin in sporadic colorectal carcinomas is not a satisfactory prognostic marker, the immunohistochemical detection of absent PTEN expression may prove useful in identifying poor outcome in individuals with sporadic MSS colorectal carcinoma.

In der vorliegenden Arbeit werden mit den Jahren 2005/2006 und 2007 qualitätsrelevante Parameter von Patienten mit einem kolorektalen Karzinom vor und unmittelbar nach Gründung des Darmzentrums an der Universitätsklinik Leipzig analysiert. Ziel dieser Arbeit war es zu untersuchen, welchen Einfluss die Gründung eines zertifizierten Darmzentrums kurzfristig auf die Behandlungsqualität von Patienten mit einem kolorektalen Karzinom hat. Die durch die Deutsche Krebsgesellschaft festgelegten Struktur- bzw. Ergebnisparameter wurden für die Jahre 2005 und 2006 retrospektiv - ab 2007 kontinuierlich erfasst. Die meisten, aber nicht alle Anforderungen der Deutschen Krebsgesellschaft wurden erreicht, bzw. umgesetzt. So zeigte sich eine bessere Dokumentation der Behandlung, insbesondere in der Pathologie. Ausserdem konnte eine Zunahme der Fallzahlen verzeichnet werden. Die Ergebnisse der Arbeit zeigen, dass durch eine Zertifizierung als Darmzentrum zunächst eine Verbesserung der Dokumentation und Standardisierung der Therapie bewirkt werden kann. Kurzfristig kann in einigen, aber nicht allen Behandlungsparametern, eine Qualitätsverbesserung, insbesondere in der Chirurgie, erreicht werden.

No description available.

Hyperactive Wnt signaling is the seminal event in colorectal cancer (CRC) pathogenesis, where β-catenin serves as a key Wnt mediator enhancing CRC cell proliferation and survival. c-Cbl is a unique E3 ligase, which degrades both mutant and active (tumorigenic) β-catenin. c-Cbl phosphorylation at tyrosine 731 (Y731) regulates its binding and down regulation of β-catenin specifically in the presence of Wnt ligand (Wnt-on state). Since aberrant Wnt signaling activation is found in almost all cases of human CRC, it would be critical to understand the influence of c-Cbl phosphorylation on CRC cell survival. We hypothesized that c-Cbl phosphorylation regulates CRC cell survival in a Wnt dependent manner, a state that is mediated through mutations in β-catenin or adenomatosis polyposis coli (APC). Cbl phosphorylation was examined in a panel of Wnt-off cells with wild-type β-catenin and APC CRC cell line (RKO cell line) and Wnt-on cell lines with mutant APC (Wnt-on- DLD1, HCT15 cell line) or mutant β-catenin (HCT116) using phospho-specific antibodies to c-Cbl tyrosine residues at 700 (Y700), 731 and 774 (Y774) positions. Biological significance of specific phosphorylation sites was evaluated with phospho-inactive mutants of c-Cbl (Y700F, Y731F and Y774F) using both the MTT cell proliferation assay and the non-adherent colony formation assay. Potential meditators of c-Cbl were examined using immunoblotting. Here we show that c-Cbl was phosphorylated at all three major phosphorylation sites (Y700, Y731 and Y774) in both Wnt-off and Wnt-on CRC cell lines. However, the amount of phosphorylation was reduced in Wnt-on CRC cell lines (DLD1, HCT116 and HCT15) compared to Wnt-off (RKO) cell line. Wild-type c-Cbl significantly enhanced survival in RKO cell lines and reduced survivability in DLD1 cell lines. In contrast to the effect of wild-type c-Cbl, Y731F increased CRC cell survival and non-adherent colony forming units. Our preliminary data suggests that c-Cbl Y731 mutation regulates CRC survival through β-catenin. c-Cbl is heavily phosphorylated in CRC cell lines, where wild-type c-Cbl significantly inhibits cell survival in Wnt-on and enhances cell survival in Wnt-off CRC cell lines. Furthermore, our data indicates that Y731 influences CRC survival and colony formation only in Wnt-on cell lines. Though further validation is required, this dichotomy in the effect of c-Cbl phosphorylation on CRC survival being mediated by Wnt status can be further explored as a potentially novel therapeutic target in mutant CRC tumors, which represent more than 90% of CRC cases in humans.

No description available.

No description available.

Introduction: Colorectal cancer (CRC) is the most common malignant tumor in both sexes in the Czech Republic. Prognostic factors in CRC can be classified as clinical (stage at the time of diagnosis, histological type of tumor), genetic (RAS, BRAF), immunological (Immunoscore)and biochemical (CEA, CA 19-9, miRNA). MicroRNAs (miRNAs) regulate the expression of oncogenes and tumor suppressors. The regulatory function of miRNAs is influenced by single nucleotide polymorphisms (SNPs) of target miRNA binding sites (miRSNPs). Aims: To evaluate the currently available prognostic factors for CRC patients treated using targeted therapies and assess the role of novel ones, including miRNA. Methods: The thesis includes clinical works focused on targeted treatment of colorectal cancer, original work focused on the role of miRNA in colorectal cancer pathogenesis and especially as a prognostic and predictive marker, work focused on functional polymorphisms of DNA repair genes and a review article summarizing biochemical factors influencing the effect of fluoropyrimidine cytostatics in the treatment of colorectal cancer. Results: We have identified miR-17/92 as a non-invasive biomarker for predicting post-treatment prognosis in patients with a higher risk of relapse, as well as miRSNPs rs8679 polymorphisms as a...

Das Kolorektale Karzinom (KRK) ist eines der häufigsten malignen Erkrankungen, an der in Deutschland jährlich 26000 Menschen versterben. Auf der Suche nach einem neuen Biomarker für dieses Malignom wurde in dieser Arbeit L1-CAM, ein neuronales Zell-Adhäsionsmolekül, untersucht. Es ist, exprimiert an der Zelloberfläche, assoziiert mit einem signifikant schlechteren Outcome bedingt durch eine raschere lokale Tumorausbreitung und Metastasierung. Es zeigte sich anhand der Untersuchung von 62 Tumorpräparate und 39 präoperativ gewonnenen Seren, dass L1-CAM sowohl immunhistologisch nachgewiesen auf der Tumoroberfläche als auch mittels ELISA bestimmt im Serum der Patienten nachweisbar ist. Patienten mit L1-CAM positiven Tumoren waren im Mittel deutlich jünger als Patienten ohne L1-CAM Expression (60 vs. 69 Jahre). Zudem zeigte sich, dass Patienten mit schwach L1-CAM positiven Tumoren im Mittel einen signifikant höheren BMI aufwiesen (Kruskal Wallis Test p=0,0354). Die L1-CAM Expression hatte in unserem Patientengut keinen signifikanten Einfluss auf die Tumorausbreitung, wenngleich wir eine häufigere Metastasierung in die Leber (44%) bei L1-CAM positiven Tumoren gegenüber Patienten ohne L1-CAM Expression im Tumor (29%) beobachteten. Gleiches gilt für die Infiltration der Perineuralscheiden durch Tumorzellen. Bei der Untersuchung der L1-CAM Serumkonzentrationen zeigte sich im Mittel kein signifikanter Unterschied zu einer gesunden Vergleichsgruppe, sodass L1-CAM als Serum-Tumormarker ungeeignet ist.

Colorectal carcinoma (CRC) is often lethal when invasion and/or metastasis occur. 15-lipoxygenase-1 (15-LO-1), an enzyme of the inflammatory eicosanoid pathway, oxidatively metabolizes linoleic acid and its expression is repressed in CRC. In the present study, the hypothesis that the lack of 15-LO-1 expression in CRC cells may contribute to the tumorigenesis was investigated. Therefore 15-LO-1 was introduced to colon cancer cell line HT-29 that does not have detectable levels of the 15-LO-1. The HT-29 cells were transiently transfected with the eukaryotic expression vector pcDNA3.1-15-LO-1 and the effects of 15-LO-1 expression on the proliferation, apoptosis as wells as metastatic potential of the cells were investigated. Cellular proliferation was analyzed by MTT assay and the apoptotic potential of 15-LO-1 was evaluated by acridine orange, floating cell ratio and caspase-3 assays as well as expression levels of the antiapoptotic protein XIAP. Cellular migration and invasion were investigated by Boyden chamber migration and Matrigel invasion assay.The data indicates that 15-LO-1 expression significantly decreased cell proliferation and increased apoptosis. In addition, a significant reduction was observed in migratory and invasive capacity 15-LO-1 expression also significantly reduced the expression of metastasis associated 1 protein (MTA-1). Taken together we propose that 15-LO-1 expression in CRC can inhibit colon cancer cell growth through induction of apoptotic cell death and may contribute to the inhibition of metastatic capacity in vitro which may be exploited for therapeutic purposes.