Verhandlungen der Deutschen Gesellschaft fur Pathologie最新文献

The ligand insulin-like growth factor (IGF)-II is highly overexpressed in human hepatocellular carcinoma (HCC) and promotes tumour cell growth. Thus, this signalling axis is a prime target for potential anti-cancer therapies. In this context, gene-specific siRNA against IGF-signalling components as well as IGF1R selective receptor tyrosine kinase (RTK)-inhibitors (tyrphostins) may therefore offer new therapeutic options since both small interfering RNAs (siRNA) and small inhibitory molecules significantly reduce IGFIR signalling in HCC cell lines. However, since highly specific inhibition by siRNA is currently not applicable in the treatment of cancer, selective RTK-inhibitors represent the most promising approach for future therapeutic strategies.

With the introduction of high throughput methods for the parallel detection of the activity of many thousands of genes, a new dimension was opened. Meanwhile almost all types of tumor entities have been investigated by this technique leading to molecular gene expression signatures which were able to subdivide even histological uniform tumor entities. The correlation of the molecular signatures with the retrospective clinical data demonstrated in many instances that these molecular subdivisions provided meaningful results. Therefore the question arises as to whether this molecular characterization should also become a part of the diagnostic routine work. Before this question can be finally answered the impact of the molecular signatures should be confirmed in prospective clinical trials. Furthermore, the results of the high throughput technologies has to be adapted to order to be applicable to RNA extracted from formalin-fixed tissue specimens. This development has already started and should be performed within the pathologies.

Non-muscle invasive bladder cancer is a heterogenous disease whose management is dependent upon the risk of progression to muscle invasion. Although the recurrence rate is high, the majority of tumors are indolent and can be managed by endoscopic means alone. The prognosis of muscle invasion is poor and radical treatment is required if cure is to be obtained. Progression risk in non-invasive tumors is hard to determine at tumor diagnosis using current clinicopathological means. To improve the accuracy of progression prediction various biomarkers have been evaluated. To discover novel biomarkers several authors have used gene expression microarrays. Various statistical methods have been described to interpret array data, but to date no biomarkers have entered clinical practice. Here, we describe a new method of microarray analysis using neurofuzzy modeling (NFM), a form of artificial intelligence, and integrate it with artificial neural networks (ANN) to investigate non-muscle invasive bladder cancer array data (n=66 tumors). We develop a predictive panel of 11 genes, from 2800 expressed genes, that can significantly identify tumor progression (average Logrank p = 0.0288) in the analyzed cancers. In comparison, this panel appears superior to those genes chosen using traditional analyses (average Logrank p = 0.3455) and tumor grade (Logrank, p = 0.2475) in this non-muscle invasive cohort. We then analyze panel members in a new non-muscle invasive bladder cancer cohort (n=199) using immunohistochemistry with six commercially available antibodies. The combination of 6 genes (LIG3, TNFRSF6, KRT18, ICAM1, DSG2 and BRCA2) significantly stratifies tumor progression (Logrank p = 0.0096) in the new cohort. We discuss the benefits of the transparent NFM approach with respect to other reported methods.

HSP90's are overexpressed in different cancer types and they probably are required to sustain aberrant signalling in malignant cells. Recently, pharmacological inhibition of HSP90 was found to suppress growth of myeloma cell lines and in primary myeloma cells. Therefore, we wanted to investigate the role of HSP90alpha and HSP90beta in the pathogenesis of malignant myeloma (MM) in more detail. Immunohistochemistry was employed to examine the expression of HSP90alpha and HSP90beta in MM. The importance of HSP90 for survival of MM -cells was investigated by SiRNA-mediated knockdown of HSP90 and blockade of the IL-6R/STAT3 and the MAPK signaling pathways in vitro. HSP90alpha and HSP90beta were overexpressed in majority of investigated MM cases, but not in MGUS or in normal plasma cells. SiRNA-mediated knockdown of HSP90 or treatment with the novel HSP90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. The knockdown of HSP90alpha was sufficient to induce apoptosis. This effect was strongly increased when both HSP90s were targeted, indicating a cooperation of both. HSP90 critically contributes to myeloma survival in the context of its microenvironment and therefore strengthen the potential value of HSP90 as a therapeutic target.

Unlabelled: The conversion of epithelial cells in a mesenchymal cell type is called "epithelial-mesenchymal-transition" (EMT). This process is defined by a loss of epithelial specific characteristics such as cell adhesion, polarity and a reorganization of cytoskeletal proteins. EMT has been shown to be involved in progression of cancer and in obstructive renal fibrosis. In this study we analyzed liver tissues in a bile-duct ligation model of rats and human liver biopsies with cholestatic fibrosis and chronic hepatitis c infection to determine if biliary epithelial cells undergo phenotypical and functional changes during chronic injury.

Methods: Liver tissue of rats and human patients was examined by immunohistochemistry using antibodies against epithelial and mesenchymal specific targets as well as molecules of potentially activated signaling pathways. To study contribution of biliary epithelial cells in extracellular matrix production we performed laser microdissection combined with real-time PCR.

Results: Bile duct ligation in rats induced a prominent biliary epithelial proliferation and a pronounced expression of vimentin was observed in biliary epithelial cells, whereas no vimentin expression was detectable in bile duct cells of sham operated rats. In human liver biopsies from patients with cholestatic fibrosis and chronic hepatitis c infection a prominent biliary expression of vimentin could be shown. Despite this, epithelial marker proteins were still detectable. Further, we observed collagen I mRNA expression in laser microdissected bile ducts.

Conclusion: Biliary epithelial cells show cytoskeletal rearrangements during chronic liver injury towards a mesenchymal phenotype. The detection of collagen I mRNA in bile duct cells suggests that they might participate in extracellular matrix production.

Histomorphological evaluation of bone marrow trephines and smears represents the major approach to diagnose the chronic myeloproliferative diseases (CMPD) and the myelodysplastic syndromes (MDS). However, rising insights into molecular pathogenesis of human diseases strengthen the attempt of pathologists to define and to detect underlying defects beyond the microscope. Since discovery of the Philadelphia chromosome in chronic myeloid leukemia as the first specific molecular abnormality ever detected in a human neoplasia the gain of knowledge of molecular pathomechanisms in Philadelphia chromosome negative (Ph-) CMPD was rather sparse. A decisive breakthrough in Ph CMPD was the finding of JAK2 (V617F) derived from a somatic point mutation in the majority of patients with polycythemia vera (P.vera) and half of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). It therefore can not be overestimated that detection of JAK2 (V617F) in a suspective myeloproliferation now enables a clearcut discrimination of a true Ph CMPD from a reactive state, e.g. P.vera from reactive erythrocytosis. Interestingly, a basic principle of molecular defects demonstrable in CMPD and related disorders seems to be the involvement of genes with kinase activities. Some of those genes will be discussed in more detail. In primary MDS, karyotyping via classical cytogenetics is the predominant molecular approach to estimate prognosis, e.g. -Y, del(5q) and del(20q) represent favourable anomalies. Indeed, in 5q- syndromes karyotyping enables definite subtyping and allows clinicians and patients to expect a good prognosis. Until now, dozens of molecular abnormalities such as mutations in AML1, FLT3 and Ras as well as epigenetic alterations of genes have been identified to various degrees in MDS subtypes. Some of them seem to be involved in disease initiation ("master event") and others might indicate disease progression. However, even though useful for further dissection of molecular pathomechanisms the majority of aberrations currently does not serve as potent markers in the daily routine. Nevertheless, in CMPD and MDS the importance of molecular analyses for diagnosis, estimation of prognosis, and disease monitoring will further increase in a foreseeable period of time.

The prognostic and predictive impact of protein expression profiles was analyzed in high-risk breast cancer patients who had previously been shown to benefit from high-dose chemotherapy (HDCT) in comparison to dose-dense chemotherapy (DDCT). Using tissue microarrays, the expression of 34 protein markers was evaluated in 236 patients who had received either HDCT or DDCT (in the WSG AM01 trial). 1) 24 protein markers of the initial panel of 34 markers were sufficient to identify five profile clusters by K-means clustering: luminal A (27%), luminal B (12%), HER-2 (21%), basal-like (13%) cluster and a so called 'multiple marker negative'=MMN cluster (27%) characterized by the absence of specifying markers. 2) After DDCT, HER-2 and basal-like groups had significantly worse event-free survival (EFS) (HR 3.6 (95% CI, 1.65-8.18; p = 0.001) and HR 3.7 (95% CI, 1.68-8.48); p < 0.0001), respectively) when compared to both luminal groups. 3) After HDCT, the hazard ratio was 1.5 (95% CI, 0.76-3.05) for EFS in the HER-2 subgroups and 1.1 (95% CI, 0.37-3.32) in the basal-like subgroups which indicates a better outcome for patients in the HER-2 and basal-like subgroups who received HDCT. Protein expression profiling in high-risk breast cancers identified 5 subtypes, which differed with respect to survival and response to chemotherapy: In contrast to luminal A and B subtypes, HER-2 and basal-like subgroups had a significant predictive benefit from HDCT when compared to DDCT.

Aims: Induction of apoptosis by the death ligand TRAIL might be a promising therapeutic approach in colorectal cancer therapy. However, some colon cancer cells are resistant to TRAIL because of the expression of anti-apoptotic proteins, such as FLIP. We studied the role of FLIP for apoptosis resistance in colon cancer and developed an approach to overcome the resistance to TRAIL.

Methods: The mechanisms of TRAIL-induced cell death in colon cancer cells were studied by Western blot analysis, apoptosis assays, transient and stable transfections, siRNA-mediated knockdown, and FACS analysis.

Results: The anti-apoptotic protein FLIP is expressed in the majority of colon carcinoma. Stable over-expression of FLIP renders colon carcinoma cells resistant to the death ligand, TRAIL. siRNA-mediated down-regulation of FLIP sensitizes the cells to TRAIL-induced apoptosis. FLIP-expressing colon cancer cells can be sensitized to TRAIL-induced apoptosis by the anti-diabetic drug troglitazone. Troglitazone induces a pronounced reduction in protein expression levels of FLIP. The troglitazone-dependent down-regulation of FLIP occurs on a post-translational level and involves the accelerated FLIP degradation by the proteasome. Moreover, troglitazone suppresses the expression of the anti-apoptotic protein, survivin, and induces the cell surface expression of the TRAIL receptor 2.

Conclusions: The anti-apoptotic FLIP protein plays an important role in apoptosis resistance of colon carcinoma cells. Troglitazone down-regulates FLIP and sensitizes the cells to TRAIL-induced apoptosis. A combined treatment with troglitazone and TRAIL might be a promising experimental therapy for some forms of colorectal cancer because troglitazone sensitizes tumor cells to TRAIL-induced apoptosis via various mechanisms, thereby minimizing the risk of acquired tumor cell resistance.

It has been suggested that mutation of FGFR3 is associated with non-invasive tumors of low malignant potential and low risk of recurrence and progression. The aim of this study was to analyze the distribution of FGFR3 mutations in bladder tumors of different grade and stage and to determine the relation of FGFR3 mutations to chromosomal alterations detected by CGH. Frozen sections of 100 bladder cancer samples served as templates for manual microdissection. DNA was isolated from dissected samples containing at least 80% tumor cells. Mutations in FGFR3 were analyzed by SNaPshot analysis. CGH was carried out according to standard protocols. FGFR3 mutations were detected in 45 out of 92 samples (48.9 %). Concerning T-category, the following mutation frequencies occurred: pTa - 69 %, pT1 - 38 %, pT2/3 - 0 %. The mutation frequency was significantly associated with tumor grade: G1 - 72%, G2 - 56%, G3 - 4%. In pTaG1 tumors, mutations were found in 74 %. A significant lower number of genetic alterations per tumor detected by CGH was associated with FGFR3 mutations (2 vs. 8). This association was also seen in pTaG1 tumors: 2.5 (with mutation) vs. 7.5 (without mutation). Our results confirm that FGFR3 mutations characterize non-invasive low-risk tumors of low malignancy. The low malignant potential of these tumors is underlined by a low number of chromosomal alterations per tumor. Therefore, FGFR3 could represent a prognostic marker of chromosomally stable tumors with low malignant potential.

Most new treatment principles are based on pathophysiological knowledge. They are, however, only effective in subgroups of patients where the pathophysiological concepts apply. The definition of the respective patient groups using clinical and laboratory findings is rather unsuccessful. Pharmakogenetic approaches have as well been disappointing. Since outcomes are often multifactorial single polymorphisms have not been sufficient. Predictive pathology will need to use gene signatures or functionally defined genetic markers in order to solve the problems.