Ruth Knuechel

Variable β-catenin expression in colorectal cancers indicates tumor progression driven by the tumor environment

Invasion and dissemination of well-differentiated carcinomas are often associated with loss of epithelial differentiation and gain of mesenchyme-like capabilities of the tumor cells at the invasive front. However, when comparing central areas of primary colorectal carcinomas and corresponding metastases, we again found the same differentiated epithelial growth patterns. These characteristic phenotypic changes were associated with distinct expression patterns of β-catenin, the main oncogenic protein in colorectal carcinomas, and E-cadherin. Nuclear β-catenin was found in dedifferentiated mesenchyme-like tumor cells at the invasive front, but strikingly, as in central areas of the primary tumors, was localized to the membrane and cytoplasm in polarized epithelial tumor cells in the metastases. This expression pattern was accompanied by changes in E-cadherin expression and proliferative activity. On the basis of these data, we postulate that an important driving force for progression of well-differentiated colorectal carcinomas is the specific environment, initiating two transient phenotypic transition processes by modulating intracellular β-catenin distribution in tumor cells.

Activated transcription factor nuclear factor-kappa B is present in the atherosclerotic lesion.

Nuclear factor-kappa B (NF-kappaB)/Rel transcription factors play an important role in the inducible regulation of a variety of genes involved in the inflammatory and proliferative responses of cells. The present study was designed to elucidate the implication of NF-kappaB/Rel in the pathogenesis of atherosclerosis. Activation of the dimeric NF-kappaB complex is regulated at a posttranslational level and requires the release of the inhibitor protein IkappaB. The newly developed mAb alpha-p65mAb recognizes the IkappaB binding region on the p65 (RelA) DNA binding subunit and therefore selectively reacts with p65 in activated NF-kappaB. Using immunofluorescence and immunohistochemical techniques, activated NF-kappaB was detected in the fibrotic-thickened intima/media and atheromatous areas of the atherosclerotic lesion. Activation of NF-kappaB was identified in smooth muscle cells, macrophages, and endothelial cells. Little or no activated NF-kappaB was detected in vessels lacking atherosclerosis. Electrophoretic mobility shift assays and colocalization of activated NF-kappaB with NF-kappaB target gene expression suggest functional implications for this transcription factor in the atherosclerotic lesion. This study demonstrates the presence of activated NF-kappaB in human atherosclerotic tissue for the first time. Atherosclerosis, characterized by features of chronic inflammation and proliferative processes, may be a paradigm for the involvement of NF-kappaB/Rel in chronic inflammatory disease.

Nuclear factor κB is activated in macrophages and epithelial cells of inflamed intestinal mucosa

BACKGROUND & AIMS Transcription factors of the nuclear factor kappaB (NF-kappaB) family play an important role in the regulation of genes involved in inflammation. In inflammatory bowel diseases, proinflammatory cytokines known to be regulated by NF-kappaB are involved. The aim of this study was to investigate the role of NF-kappaB activation during mucosal inflammation in situ. METHODS A monoclonal antibody, alpha-p65mAb, was applied for immunofluorescence and immunohistochemical analysis that recognizes activated NF-kappaB. Electrophoretic mobility shift assay was used to directly demonstrate the presence of active DNA-binding NF-kappaB. RESULTS Using the alpha-p65mAb antibody, activated NF-kappaB could be found in biopsy specimens from inflamed mucosa but was almost absent in uninflamed mucosa. The number of cells showing NF-kappaB activation correlated with the degree of mucosal inflammation but was not significantly different between inflamed mucosa from patients with Crohns disease, ulcerative colitis, and nonspecific colitis or diverticulitis. NF-kappaB activation was localized in macrophages and in epithelial cells as identified by double-labeling techniques. Electrophoretic mobility shift assay with isolated lamina propria mononuclear cells and epithelial cells confirmed these results. CONCLUSIONS This study shows for the first time the activation of NF-kappaB during human mucosal inflammation in situ. In addition to macrophages, epithelial cells contained activated NF-kappaB, indicating an involvement in the inflammatory process.

WIF1, a component of the Wnt pathway, is down‐regulated in prostate, breast, lung, and bladder cancer

To detect novel Wnt‐pathway genes involved in tumourigenesis, this study analysed the RNA expression levels of 40 genes of the Wnt pathway by chip hybridization of microdissected matched pairs of 54 primary prostate carcinomas. Eleven genes showed greater than two‐fold differential expression in at least 10% of prostate cancers. Three of these genes encode extracellular components of the Wnt pathway (WNT2, WIF1, SFRP4); two are receptors (FZD4, FZD6); two belong to the intracellular signal cascade (DVL1, PPP2CB); one regulates transcription (TCF4); and three represent genes regulated by this pathway (CCND2, CD44, MYC). While SFRP4, FZD4, FZD6, DVL1, TCF4, and MYC are up‐regulated, WIF1, WNT2, PPP2CB, CCND2, and CD44 are down‐regulated in certain prostate cancer patients. Wnt inhibitory factor 1 (WIF1) and secreted frizzled related protein (SFRP4) showed the most significant aberrant expression at the RNA level. WIF1 was down‐regulated in 64% of primary prostate cancers, while SFRP4 was up‐regulated in 81% of the patients. Immunohistochemical analysis using a polyclonal antibody revealed strong cytoplasmic perinuclear WIF1 expression in normal epithelial cells of the prostate, breast, lung, and urinary bladder. Strong reduction of WIF1 protein expression was found in 23% of prostate carcinomas, but also in 60% of breast, 75% of non‐small cell lung (NSCLC), and 26% of bladder cancers analysed. No significant association between WIF1 down‐regulation and tumour stage or grade was observed for prostate, breast or non‐small cell lung carcinomas, indicating that loss of WIF1 expression may be an early event in tumourigenesis in these tissues. However, down‐regulation of WIF1 correlated with higher tumour stage in urinary bladder tumours (pTa versus pT1–pT4; p = 0.038). Copyright

Multicellular spheroids: a three-dimensional in vitro culture system to study tumour biology

The growth of tumour cells as three‐dimensional multicellular spheroids in vitro has led to important insights in tumour biology, since properties of the in vivo‐tumour such as proliferation or nutrient gradients, can be studied under controlled conditions. While this review starts with an update of recent data on spheroid monocultures, especially concerning tumour microenvironment and therapeutic modalities, the main emphasis is put on the spectrum of heterologous cultures which have evolved in previous years. This type of culture includes tumour cell interaction with endothelial, fibroblast or immunocompetent cells. The relation of the spheroid culture model to other types of three‐dimensional culture and our critical evaluation and presentation of the technical aspects of growing and analysing spheroids are included in the text. These topics are chosed to help the experimental pathologist design experiments with tumour spheroids and to stimulate discussion.

The osteogenic differentiation of adult bone marrow and perinatal umbilical mesenchymal stem cells and matrix remodelling in three-dimensional collagen scaffolds.

Adult human mesenchymal stem cells from bone marrow (BM-MSC) represent a promising source for skeletal regeneration. Perinatal MSC from Whartons Jelly of the umbilical cord (UC-MSC) are expected to possess enhanced differentiation capacities due to partial expression of pluripotency markers. For bone tissue engineering, it is important to analyse in vitro behaviour of stem cell/biomaterial hybrids concerning in vivo integration into injured tissue via migration, matrix remodelling and differentiation. This study compares the cell-mediated remodelling of three-dimensional collagen I/III gels during osteogenic differentiation of both cell types. When activated through collagen contact and subjected to osteogenic differentiation, UC-MSC differ from BM-MSC in expression and synthesis of extracellular matrix (ECM) proteins as shown by histology, immunohistochemistry, Western Blot analysis and realtime-RT-PCR. The biosynthetic activity was accompanied in both cell types by the ultrastructural appearance of hydroxyapatite/calcium crystals and osteogenic gene induction. Following secretion of matrix metalloproteinases (MMP), both MSC types migrated into and colonised the collagenous matrix causing matrix strengthening and contraction. These results indicate that UC-MSC and BM-MSC display all features needed for effective bone fracture healing. The expression of ECM differs in both cell types considerably, suggesting different mechanisms for bone formation and significant impact for bone tissue engineering.

Clonality of multifocal urothelial carcinomas: 10 years of molecular genetic studies

Multifocal occurrence and frequent recurrence are characteristic features of urothelial carcinomas of both the urinary bladder and the upper urinary tract. To describe the clonal nature of these tumors, 2 theories have been proposed. The monoclonality hypothesis describes the multiple tumors as descendants of a single genetically transformed cell spreading throughout the urothelium. In contrast, field cancerization caused by carcinogen exposure of the urothelium may lead to independent development of synchronous or metachronous nonrelated tumors at different sites of the urothelial tract. In the last 10 years, a multitude of molecular genetic studies have investigated the clonality of multifocal urothelial carcinomas. The majority of studies revealed a monoclonal origin of the multiple tumors. However, most of these studies investigated advanced invasive carcinomas. A small but significant proportion of multifocal urothelial carcinomas appear to arise from different clones, supporting the field‐cancerization hypothesis. Oligoclonal tumors might be more common in precursor lesions and early tumor stages. The frequent monoclonality found in patients with advanced tumors could be due to outgrowth of 1 tumor cell clone with specific genetic alterations. Two important mechanisms appear to be important for the spread of malignant cells: intraluminal seeding and intraepithelial migration. Investigation of the entire urothelial lining in patients with urothelial tumors should provide further insight into the development of multifocal urothelial carcinomas.

Evidence for oligoclonality and tumor spread by intraluminal seeding in multifocal urothelial carcinomas of the upper and lower urinary tract

Multifocality and recurrence of urothelial carcinoma may result from either the field effect of carcinogens leading to oligoclonal tumors or monoclonal tumor spread. Previous molecular studies, favoring the monoclonality hypothesis, are mostly limited to the urinary bladder. We investigated genetic alterations in a total of 94 synchronous or metachronous multifocal tumors from 19 patients with at least one tumor both in the upper and lower urinary tract. Loss of heterozygosity (LOH) was determined using eight markers on chromosome 9 and one marker on 17p13 (p53). Microsatellite instability was investigated at six loci and protein expression of MSH2 and MLH1 was evaluated by immunohistochemistry. In addition, exons 5–9 of the p53 gene were sequenced. Deletions at chromosome 9 were found in 73% of tumors and at 17p13 in 18% of tumors. There was no significant difference in the frequency of LOH in the upper and lower urinary tract. Deletions at 9p21 were significantly correlated with invasive tumor growth. The pattern of deletion revealed monoclonality of all tumors in nine patients. In five patients there were at least two tumor clones with different genetic alterations. In four of these patients the different clones occured in the bladder and subsequently in the ureter and renal pelvis. All four patients with p53 mutations revealed identical mutations in all tumors. Thus, multifocal urothelial carcinomas are frequently monoclonal, whereas others show oligoclonality, providing molecular evidence for field cancerization. Intraluminal tumor cell seeding appears to be an important mechanism of multifocal occurence and recurrence of urothelial carcinomas.

Deletions of chromosome 8p and loss of sFRP1 expression are progression markers of papillary bladder cancer

Many molecular alterations are known to occur in urothelial carcinoma of the bladder, but their significance for tumor progression is poorly understood. Deletions of chromosome 8p are frequently found in several tumor types and are often associated with progressive disease. In all, 99 bladder tumors were screened for deletions at 8p using loss of heterozygosity (LOH) and multicolor fluorescence in situ hybridization FISH analyses. Allelic loss on chromosome 8p in at least one marker was found in 25/99 (25%) tumors. There was a significant correlation of 8p deletions with invasive tumor growth and a highly significant association with papillary growth pattern in patients with invasive disease. cDNA array analyses revealed that secreted Frizzled-related protein 1 (sFRP1), an antagonist of Frizzled receptors and Wnt pathway activation on chromosome 8p12–11.1, is frequently downregulated in bladder cancer. To investigate sFRP1 as a candidate for a putative progression-related gene on 8p, urothelial cell lines and primary urothelial carcinomas were screened for sFRP1 expression using quantitative real-time PCR, Northern blot, immunofluorescence and immunohistochemistry (IHC). Of the investigated bladder cancers, 38% showed loss of sFRP1 expression by quantitative RT-PCR. Evaluation of the protein expression by IHC using tissue microarrays containing 776 bladder cancers revealed loss or strong reduction of sFRP1 expression in 66% of cases. SFRP1 loss was associated with higher tumor stage and grade and shorter overall survival. In addition, loss of sFRP1 was an independent indicator of poor survival in patients with papillary but not with muscle invasive bladder cancer. There were neither mutations in the coding region of sFRP1 nor homozygous deletions at 8p12–11.21. However, promoter methylation was detected using methylation-specific PCR in 29% of cases. In conclusion, we could show a close correlation of chromosome 8p deletions and progression of papillary bladder tumors. The sFRP1 gene on chromosome 8p12–11.1 could be a candidate gene for the predicted, progression-related tumor suppressor gene in bladder cancer and could contribute to urothelial carcinogenesis.

Molecular Profiling of Laser-Microdissected Matched Tumor and Normal Breast Tissue Identifies Karyopherin α2 as a Potential Novel Prognostic Marker in Breast Cancer

Purpose: The aim of the present study was to identify human genes that might prove useful in the diagnosis and therapy of primary breast cancer. Experimental Design: Twenty-four matched pairs of invasive ductal breast cancer and corresponding benign breast tissue were investigated by a combination of laser microdissection and gene expression profiling. Differential expression of candidate genes was validated by dot blot analysis of cDNA in 50 pairs of matching benign and malignant breast tissue. Cellular expression of candidate genes was further validated by RNA in situ hybridization, quantitative reverse transcription-PCR, and immunohistochemistry using tissue microarray analysis of 272 nonselected breast cancers. Multivariate analysis of factors on overall survival and recurrence-free survival was done. Results: Fifty-four genes were found to be up-regulated and 78 genes were found to be down-regulated. Dot blot analysis reduced the number of up-regulated genes to 15 candidate genes that showed at least a 2-fold overexpression in >15 of 50 (30%) tumor/normal pairs. We selected phosphatidic acid phosphatase type 2 domain containing 1A (PPAPDC1A) and karyopherin α2 (KPNA2) for further validation. PPAPDC1A and KPNA2 RNA was up-regulated (fold change >2) in 84% and 32% of analyzed tumor/normal pairs, respectively. Nuclear protein expression of KPNA2 was significantly associated with shorter overall survival and recurrence-free survival. Testing various multivariate Cox regression models, KPNA2 expression remained a highly significant, independent and adverse risk factor for overall survival. Conclusions: Gene expression profiling of laser-microdissected breast cancer tissue revealed novel genes that may represent potential molecular targets for breast cancer therapy and prediction of outcome.