[Heterotopic tissue in the gastrointestinal tract]. / Ektopes Gewebe des Gastrointestinaltraktes.

Heterotopia of the gastrointestinal tract is a common finding. This is due to the complex embryogenesis and the relative ease to detect heterotopic tissue during endoscopy. The reason for biopsy is mostly to rule out neoplasms or to define specific causes of inflammation. Heterotopic tissue can occur in any location of the gastrointestinal tract. The most frequent are gastric heterotopia, pancreatic heterotopia, and heterotopia of Brunner's gland. On rare occasions, heterotopic tissue of salivary gland type as well as heterotopias of apocrine glands, thyroid, and prostatic tissue have been described. The most frequently involved organs are the small intestine, in particular the duodenum, the esophagus, and the stomach. Heterotopia of the large bowel occurs exclusively in the rectum. Most heterotopias do not cause symptoms and are easily diagnosed by biopsy and histology. However, depending on location, size, and the kind of underlying heterotopic tissue, they may cause significant complications, such as inflammation, ulceration and perforation, obstruction, intussusception, and severe life-threatening bleeding. Another rare but significant complication is neoplasia. Gastric heterotopias may give rise to pyloric gland adenomas within the bowel or rarely adenocarcinomas of the esophagus. Pancreatic heterotopia can be complicated by ductal type pancreatic adenocarcinomas, by acinus cell carcinomas, by intraductal papillary mucinous neoplasias, and also by endocrine tumors. The present paper summarizes our current knowledge about heterotopias in a topographic clinico-pathological manner.

[Incidental finding of a cardiac paraganglioma]. / Zufallsbefund eines kardialen Paraganglioms.

Cardiac paragangliomas are extremely rare neoplasms with an incidence of 1% of all cardiac tumors and can be completely asymptomatic, therefore, diagnosis is difficult. This article reports the case of an 18-year-old man with a heart murmur detected during a routine physical examination. Echocardiography revealed a heart tumor measuring 7 cm in size in the right atrium. Due to the tumor size and the threat of tricuspid valve insufficiency, tumor resection was performed. The histopathological examination revealed a cardiac paraganglioma with positive reactions of the tumor cells for chromogranin A, synaptophysin and CD56. Differentiating a primary cardiac paraganglioma from other more common cardiac tumors and particularly from metastases of neuroendocrine neoplasms from other locations is essential not only for the further clinical treatment but also for the prognosis of the patient.

Peritoneal papillary mesothelioma in situ: BAP1 mutation with indolent behavior for 15 years.

Papillary mesothelioma in situ (PMIS) is a rare and enigmatic disease. Most instances manifest as lesions of the peritoneal serosa. The pathogenesis and behavior of peritoneal PMIS are still poorly understood, and separation from benign well differentiated peritoneal mesothelial tumors (WDPMT) may be challenging. We describe the 15-year long course of a PMIS in an adult male in which inactivating mutations of BAP1, encoding BRCA1 associated protein 1 (BAP1), were identified. Tumor samples were obtained on 2 occasions more than 8y apart. In both samples, the tumor cells were bland, with occasional focal infiltration into the stalks of larger papillary lesions. However, no invasion into subserosal adipose tissue was identified. In both samples the tumor cells did not express nuclear BAP1. Comprehensive genomic analysis of the initial tumor sample revealed a somatic inactivating mutation in BAP1 (predicted effect, Y223*) and a somatic variant of IRS2 (A701_V702insAA). An additional inactivating mutation in BAP1 (predicted effect, T69fs*5) was detected in the later sample. The patient did not receive any treatment and is still alive 15 years after initial presentation. Our experience supports the view that peritoneal PMIS may follow an indolent course for many years and prompts the question whether these tumors should uniformly be treated aggressively.

Ascitic interleukin-12 is an independent prognostic factor in ovarian cancer.

PURPOSE: The clinical impact of endogenous cytokines supplied with deterministic properties in the generation of either T helper (Th)1 -type or Th2-type immune response was investigated in patients with ovarian cancer. Whereas interleukin (IL)- 12 initiates the differentiation of naive Th0 cells toward Th1 phenotype, IL-4 and IL-10 mediate the development of Th2-type immunity. PATIENTS AND METHODS: Cytokines were determined before treatment by means of enzyme-linked immunosorbent assay (ELISA) in ascites fluid and serum of 76 patients with ovarian cancer. Cytokine levels were compared with each other and with standard clinicopathologic parameters. A stepwise logistic regression was calculated to rule out interdependence in the associations of the various variables. Survival analyses were performed with the Kaplan-Meier method and differences in survival were examined according to Mantel and Breslow. Cox proportional hazards analysis was used to identify independent prognostic factors. RESULTS: Whereas IL-10 and IL-12 were detectable in all ascites-fluid samples, IL-4 was measurable in only 43% of the specimens. With the exception of neopterin, macrophage colony-stimulating factor (M-CSF), and IL-4, determined cytokine levels were significantly elevated in ascites fluid compared with serum (P < .01). In univariate analyses, high ascitic-fluid concentrations of either neopterin, tumor necrosis factor-alpha (TNF-alpha), or IL-12 were associated with poor disease-free (P < .005) and overall (P < .01) survival. Multivariate Cox regression analysis showed ascitic-fluid IL-12 levels to be the only immunologic variable that retained independent prognostic significance (P < .03 for disease-free and P < .01 for overall survival), together with residual disease, Fédération Internationale de Gynécologie et d'Obstétrique (FIGO)-stage, and patient age. CONCLUSION: In ovarian cancer, high ascitic-fluid IL-12 levels, which may indicate a local Th1-generated immune response, are associated with disease progression.

Cytokine-regulated expression of collagenase-2 (MMP-8) is involved in the progression of ovarian cancer.

Matrix metalloproteinases (MMPs) have been implicated in ovarian cancer progression. Among them, MMP-8 that degrades type I collagen may play a crucial role. The aim of our study was to determine MMP-8 expression and regulation in ovarian cancer and its association with other MMPs and tissue inhibitors of metalloproteinases (TIMPs). Tissue microarrays (TMAs) containing tissue cylinders from 302 patients were used for immunohistochemical studies. In addition, MMP-8 expression in vitro was analysed by a specific immunoassay and PCR-analysis. MMP-7 (81%), MMP-8 (95%), MT3-MMP (100%), TIMP-2 (100%), and TIMP-3 (96%) were expressed in all the OVCAs, but the staining intensities varied. MMP-3 (6%), MMP-9 (57%) and TIMP-1 (43%) expressions were more rarely detected. Only MMP-8 expression levels correlated with tumour grade (P<0.01), tumour stage (P<0.01), and a poor prognosis (P<0.05). MMP-8 protein and gene expression in vitro was found to be significantly upregulated by interleukin-1beta (IL-1beta, P<0.01). The data indicate that MMP-8 overexpression in OVCAs is regulated by IL-1beta and that pro-inflammatory cytokines may promote the invasive potential of ovarian cancer.

Influence of heat shock protein 70 and metallothionein induction by zinc-bis-(DL-hydrogenaspartate) on the release of inflammatory mediators in a porcine model of recurrent endotoxemia.

The manipulation of stress gene expression by heavy metals provides protection against the lethal effects of endotoxemia in murine models of septic shock. Recent in vitro studies with alveolar macrophages or monocytes show that induction of the stress response in these cells is followed by a decreased liberation of major cytokines [tumor necrosis factor-alpha (TNF alpha) and interleukin-1 (IL-1)] after endotoxin challenge. These findings suggest that the increased resistance to endotoxin in vivo after stress protein induction could be explained by an altered pattern of inflammatory mediator release. Therefore, we measured the time course of thromboxane-B2 (TxB2), 6-keto-PGF1 alpha, platelet activating factor (PAF), TNF alpha, interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) formation with and without induction of the stress response in an established porcine model of recurrent endotoxemia (Klosterhalfen et al., Biochem Pharmacol 43: 2103-2109, 1992). Induction of the stress response was done by a pretreatment with Zn2+ (25 mg/kg zinc-bis-(DL-hydrogenasparate = 5 mg/kg Zn2+). Pretreatment with Zn2+ prior to lipopolysaccharide (LPS) infusion induced an increased heat shock protein 70 and metallothionein expression in the lungs, liver, and kidneys and increased plasma levels of TNF alpha, IL-1 beta, IL-6, and TxB2 as opposed to untreated controls. After LPS infusion, however, pretreated animals showed significantly decreased peak plasma levels of all mediators as opposed to the untreated group. The time course of mediator release was identical with the decreasing and increasing three peak profiles described previously. Hemodynamic data presented significantly decreased peak pulmonary artery pressures and significantly altered hypodynamic/hyperdynamic cardiac output levels in the pretreated group. In conclusion, the data show that the induction of stress proteins by Zn2+ could be a practicable strategy to prevent sepsis.

Metaplastic columnar cells in Barrett's esophagus: a common and neglected cell type.

Goblet cells are considered by most to be a prerequisite for the diagnosis of Barrett's esophagus. Columnar cells that are alcian blue (AB) positive (as are goblet cells) are commonly observed in the surface epithelium of Barrett's esophagus, but their distribution in relation to goblet cells has not previously been defined. The authors analyzed the prevalence and distribution of these cell types in the surface but not pit epithelium (where they may sometimes be present in normal gastric mucosa). The distribution of the AB-positive columnar cells was mapped out in the entire mucosa of nine esophagectomy specimens, resected for Barrett's-associated high-grade dysplasia or carcinoma, and compared with other cell types, especially goblet cells. AB-positive goblet and columnar cells were present in 87.1% +/- 5.6% and 85.7% +/- 5.9%, respectively, of the evaluated sections of Barrett's mucosa, whereas gastric-type, AB-negative cells were observed in 46.3% +/- 8.7% of the sections. In 53% of the sections, the surface epithelium contained more than 25% AB-positive cells, and in more than three quarters of these sections, AB-positive columnar cells were the dominant AB-positive cell type. No difference in the distribution of the AB-positive epithelial cells was noticed between the proximal and distal halves of the Barrett's mucosae. In the cardia region, seven of nine cases showed a few scattered AB-positive columnar cells, and five of nine cases showed a few scattered goblet cells. No AB-positive cells were found in fundic gland mucosa. These findings indicate that the metaplastic AB-positive columnar cells are more prevalent than goblet cells. They may be analogous to incomplete metaplastic cells of the stomach, and, therefore, their role in the development of neoplasia needs further study.

Epstein-Barr virus-associated Hodgkin's lymphoma and legionella pneumophila infection complicating treatment of juvenile rheumatoid arthritis with methotrexate and cyclosporine A.

We describe the case of a 53-month-old girl with juvenile rheumatoid arthritis (JRA), complicated by the occurrence of Hodgkin's lymphoma and Legionella pneumophila infection during immunosuppressive treatment with methotrexate (MTX) and cyclosporine A (CSA). The girl had received variable anti-inflammatory combination therapy, including MTX for 28 months and CSA for 3 months. Thirty-six months after the onset of arthritis, the girl presented with an enlargement of the lymph nodes of the mediastinum, the hilum of the lungs, and the abdomen. Concomitantly, a diagnosis of Legionella pneumonia was rendered. Autopsy showed Epstein-Barr virus (EBV)-associated nodular sclerosing Hodgkin's lymphoma. The neoplastic cells were positive for CD15, CD 30, and latent membrane protein 1 (LMP 1). The present case is the second reported to occur in a child, and it lends support to the hypothesis that immunosuppressive treatment may contribute to an increased risk of the development of EBV-associated lymphoproliferative disorders (LPD) in pediatric patients suffering from JRA.

Collagenous colitis: a study of the distribution of morphological abnormalities and their histological detection.

In collagenous colitis, the literature is conflicting concerning where in the colon the lesions are most likely to be present and most severe. Conflicting data furthermore shed doubt on the sensitivity of the histological detection of the morphological abnormalities and the threshold criteria for diagnosis. We addressed these questions in 56 patients with collagenous colitis. Two hundred ninety-one coded biopsy specimens were analyzed according to six standardized sites from cecum to rectum. Subepithelial collagen deposits were subjectively graded in hematoxylin and eosin (H&E) sections and quantitatively measured in trichrome-stained sections, respectively. Semiquantitative grading was also done for inflammatory changes of the lamina propria and abnormalities of the surface and crypt epithelium. The transverse colon yielded the largest percentage of biopsy specimens (83%) interpreted as diagnostic of collagenous colitis and also had the largest percentage of biopsy specimens with inflammatory changes (98%). Biopsy specimens from both the rectosigmoid and the right colon (ascending and cecum) were significantly less likely to be diagnostic (P<.01). Only 66% of specimens obtained from the rectosigmoid were diagnostic, and 18% of these were interpreted as normal. Subepithelial collagen deposits proved to be significantly thicker in the transverse (median, 46.8 microm; range, 12 to 212.4) and descending (median, 49.2 microm; range, 6 to 230.4) than in the rectosigmoid (median, 33.6 microm; range, 9.6 to 178.8) and right colon (median, 35.4 microm; range, 6 to 140.4), respectively (P<.01). Almost all biopsy specimens (97%) had collagen deposits thicker than 10 microm. However, the subjective interpretation "diagnostic of collagenous colitis" proved to be most consistent with a threshold of 30 microm. Our results indicate that biopsy specimens from at least as proximal as the transverse colon should be obtained to definitely rule out collagenous colitis. Furthermore, it is evident that in a given biopsy specimen, markedly abnormal subepithelial collagen deposition had to be present for an unequivocal histological diagnosis of collagenous colitis.

Induction of heat shock protein 70 by zinc-bis-(DL-hydrogenaspartate) reduces cytokine liberation, apoptosis, and mortality rate in a rat model of LD100 endotoxemia.

A prospective, randomized model of LD100/24 h endotoxemia was performed in male Wistar rats (n = 26; 250-300 g). The animals were divided into four groups: Group I (n = 5; saline treatment only), Group II (n = 5; Zn2+ treatment only), Group III (n = 8; saline pretreatment, lipopolysaccharide (LPS) treatment), and Group IV (n = 8; Zn2+ pretreatment, LPS treatment). Zn2+ pretreatment was carried out by intraperitoneal injection of 50 mg/kg zinc-bis-(DL-hydrogenaspartate) (10 mg/kg Zn2+). LD100/24 h endotoxemia was induced by intraperitoneal administration of 20 mg/kg LPS of the Escherichia coli strain WO111:B4. Tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 were detected by enzyme-linked immunosorbent assay (ELISA). HSP70 expression in the lungs, the liver, and the kidneys was determined by immunohistochemistry, Western blotting, and an HSP70 ELISA. Apoptosis was also detected by an in situ apoptosis detection kit (TUNEL) and a cell death detection ELISA, respectively. This rat model of endotoxemia proves the close relationship between HSP70 expression, cytokine liberation, and development of apoptosis. The data demonstrate that: 1) Zn2+ is a potent inducer of HSP70 expression; 2) the application of Zn2+ leads to slightly increased cytokine plasma levels; and 3) the manipulation of the heat shock response by Zn2+ significantly increases the survival rate after LD100 endotoxemia. Enhanced survival rate in animals pretreated with Zn2+ may be explained by increased tissue levels of HSP70, a subsequent significantly decreased liberation of the proinflammatory cytokines after LPS challenge, and a significantly decreased rate of apoptosis.

Tumour-cell-endothelial interactions: free radicals are mediators of melanoma-induced endothelial cell damage.

Damage to vascular endothelium may play an important role during metastasis. We used a three-dimensional model of tumour cell extravasation to test the hypothesis that certain types of tumour cells are able to induce vascular endothelial cell injury. Multicellular tumour spheroids (MCTS) of 14 human cancer cell lines and spheroids from two benign cell lines were transferred onto confluent monolayers of human endothelial cells (EC). MCTS from 4 of 7 melanoma cell lines induced damage of the endothelium which was closely associated with tumour cell attachment. Endothelial cell injury became evident morphologically by loss of cell membrane integrity and sensitivity to shear stress. Similar results were obtained with EC derived from human umbilical veins, umbilical arteries and saphenous veins. Addition of the oxygen radical scavenger catalase showed a dose- and time-dependent inhibition (up to 48 h) of EC damage in the case of the melanoma cell lines ST-ML-11, ST-ML-14 and SK-MEL-28. The scavenging enzyme superoxide dismutase proved to be protective (up to 12 h) in ST-ML-12 MCTS. In contrast, allopurinol, deferoxamine mesylate, ibuprofen, nor-dihydroguaretic acid, soybean trypsin inhibitor or aprotinin had no protective effect. None of the non-melanoma cancer cell lines or benign cells induced endothelial cell damage. Endothelial injury has been shown to enhance the process of metastasis. Our results suggest that free-radical-mediated endothelial cell damage may be one of the mechanisms contributing to the devastating metastatic potential of melanoma.

Modulation of CA-125 release by inflammatory cytokines in human peritoneal mesothelial and ovarian cancer cells.

In the present study the modulatory effects of inflammatory cytokines, interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), on CA-125 release in established ovarian cancer cell lines and in human peritoneal mesothelial cells (HPMC) both grown as monolayers, were investigated. The purity of mesothelial cell cultures were confirmed by the positivity of the cells for vimentin and cytokeratins 8 and 18, and their negativity for markers CD34 and CD68, thus excluding contamination by endothelial cells and macrophages. The preliminary results of CA-125 measurements in the culture medium clearly indicated differences in the pattern of CA-125 expression and release between normal and malignant cells under the influence of inflammatory cytokines. Furthermore, it seems that normal mesothelial cells play a crucial role as a source of CA-125 found in ascitic fluid or in pleural effusions and possibly even in the serum since secretion of this tumor marker into the culture medium was found to be significantly higher in HPMC than in ovarian cancer cells.

Peritoneal mesothelial cells as a significant source of ascitic immunostimulatory protein 90K.

The tumor associated antigen 90K is known to possess cytokine-like modulatory properties on the cellular immune system, whereby accessory cells are the primary target of this molecule. In 67 ovarian cancer patients presenting with significant amounts of ascites, immunostimulatory protein 90K was detected in all ascitic fluid samples examined. Furthermore, 90K levels correlated to ascitic s-IL-2R content. To elucidate the source of protein 90K in ascitic fluid; its in vitro release was investigated in primary cultured normal human peritoneal mesothelial cells (HPMC). Peritoneal mesothelium was found to produce five-fold more 90K than ovarian cancer cells. Release of protein 90K was significantly increased by treatment with IFN-gamma in both mesothelial and ovarian cancer cells. In contrast neither IL-1 beta nor TNF-alpha treatment consistently influenced the secretion of 90K in either cell type.

Reflux-induced apoptosis of the esophageal mucosa is inhibited in Barrett's epithelium.

BACKGROUND: Apoptosis maintains cell homeostasis. Altered apoptosis is involved in carcinogenesis. It was our aim to investigate whether reflux esophagitis may alter apoptosis in the esophageal mucosa and whether antireflux surgery may restore normal apoptosis. METHODS: Apoptosis was studied preoperatively and postoperatively in esophageal biopsies of 39 patients with various grades of reflux esophagitis and in Barrett's mucosa using the TUNEL method. Biopsies were also taken from lesions of the squamous epithelium adjacent to the Barrett's mucosa. RESULTS: Apoptosis increased with the severity of esophagitis. Apoptosis was low in Barrett's epithelium. Squamous epithelium adjacent to Barrett's mucosa showed increased apoptosis. After surgery apoptosis decreased in squamous epithelium, and it remained low in Barrett's epithelium. CONCLUSIONS: Apoptosis in reflux esophagitis may be protective against increased proliferation. Low apoptosis following antireflux surgery indicates that surgery is effective to prevent reflux-induced cell proliferation. Inhibition of apoptosis in Barrett's may promote carcinogenesis. This may not change following surgery.

AL 721: a potent membrane modulating agent of human T-lymphocytes?

This report deals with AL 721, a reputedly potent membrane fluidizing agent. A correlation has been sought between the effects of AL 721 on membrane fluidity and mitogen responsiveness of human peripheral blood lymphocytes. The AL 721-induced increase in membrane "fluidity", as measured by fluorescence polarisation with 1,6-diphenyl-1,3,5-hexatriene, was found to be an artefact arising from lipid uptake by monocytes. Mitogen responses were enhanced by inclusion of AL 721 in the serum-free culture medium. However, this observation is more likely explained by provision of lymphocytes with nutritional lipids required for optimal growth in vitro, than altered responsiveness of "fluidized" lymphocytes.

Adjuvant extension of chemotherapy after neoadjuvant therapy may not improve outcome in early-stage breast cancer.

INTRODUCTION: Neoadjuvant chemotherapy (NAC) is equivalent to adjuvant therapy (AdC) in terms of survival and disease-free interval. Many institutions add AdC after NAC and surgery. However, such extended chemotherapy (ExC) is not evidence based. Study aim was to investigate if ExC improved disease-free (DFS) and overall survival (OS). PATIENTS AND METHODS: From 1998 to 2006 356 consecutive patients received NAC (45 pts), AdC (221 pts) or ExC (90 pts). We analysed these 3 groups to determine effects of ExC and to identify patients who might benefit. NAC consisted in 93% of 3-6 cycles of epirubicin+docetaxel, AdC comprised EC+/-taxanes in 72%. Median age in the NAC, AdC, and ExC-groups was 54, 56 and 52 years with follow-up of 30, 57, and 55 months. RESULTS: After NAC, 35% achieved downstaging and 10% pathologic complete remission. Surprisingly ExC seemed to result in reduction of 5-year DFS: compared to 85% and 82% after NAC and AdC, DFS was 61% after ExC (p=0.001). OS was not significantly affected (79, 91, and 78% after NAC, AdC and ExC, p=0.13). In multivariate analysis after correction for age, menopausal status, stage, grading, hormone receptors, her2-status, radiotherapy and surgery, ExC seemed to adversely affect DFS (HR 2.15, p=0.008), loco-regional and distant recurrence-rates (HR 3.0, p=0.03 and HR 2.0, p=0.02). DISCUSSION: In this single-center analysis ExC could not show advantages in terms of DFS and OS. Because multivariate analyses of retrospective data cannot account for all potential biases, these data require confirmation in randomized clinical trials. Until then, extended chemotherapy should be considered carefully. As in previous studies, no differences were found between NAC and AdC groups.

[Pathology of small intestine transplantation]. / Pathologie der Dünndarm-Transplantation.

Small bowel transplantation is being increasingly performed to treat patients with irreversible intestinal failure or short bowel syndrome. Worldwide approximately 100 transplantations are currently performed per year. Technical advances and new immunosuppressive strategies adopted during the last 10 years have significantly improved the quality of live and survival rate of the patients. The 5-year survival rate is currently around 60%. However, the procedure still bears significant live threatening risks. Mayor problems include surgical complications like anastomotic leakage or peritonitis, acute allograft rejection, systemic infection and in later stages loss of graft function due to chronic rejection. Acute rejection is common after intestinal transplantation. It may occur any time after transplantation and is seen in 50%-80% of the patients. The characteristic changes are enterocyte apoptosis in the crypts, cryptitis and mononuclear cell infiltration with activated lymphocytes. Severe cases may reveal ulcerations or even sloughing and widespread exfoliation of the epithelium and are almost invariably associated with graft loss. The histopathological abnormalities may be patchy and occur in grossly normal mucosa. Therefore, multiple biopsies should be generally sampled for histology. Acute rejection must be distinguished from infections in particular opportunistic viral infections caused by Cytomegalovirus (CMV) or Adenovirus as well as from Epstein-Barr virus-related B-lymphocyte proliferations. Differential diagnosis also includes preservation injury and ischemia resulting in damage of the mucosal surface epithelium. Long-term graft function and survival are now increasingly determined by chronic rejection. The hallmarks of chronic rejection are obliterative arteriopathy of mesenterial vessels and progressive fibrosis of the transplant including its mesentery.

Interaction of human malignant melanoma tumor spheroids with endothelium and reconstituted basement membrane: modulation by RGDS.

Tumor-cell extravasation involves sequential adhesive interactions with vascular endothelium and the subendothelial basement membrane. We have established a 3-dimensional model in vitro to simulate these events and to elucidate targets of the anti-cell-adhesive synthetic peptide RGDS. Tumor spheroids of the melanoma cell line ST-ML-12 served as models of tumor-cell emboli and were transferred onto human umbilical vein endothelial cells. To imitate the vascular anatomy, the latter were grown on reconstituted basement membranes produced by dextran-stimulated bovine corneal endothelial cells. RGDS did not affect the homotypic aggregation of the tumor cells and only minimally inhibited the attachment of the spheroids to the reconstituted vessel. A short-term (20 min) inhibition of adhesion to denuded basement membranes was observed. The attachment was closely associated with damage to the endothelial cells by oxygen-derived free radicals. RGDS retarded endothelial injury for up to 3 hr. The most prominent effect was observed after penetration of the endothelium. RGDS suppressed the emigration of tumor cells from the attached tumor-cell cluster in a dose- and time-dependent fashion. After 12 hr, the inhibitory effect progressively declined. This was not due to loss of activity of the peptide, indicating a resistance mechanism in the melanoma cells. On purified components of the basement membrane, RGDS effectively inhibited the initial spheroid attachment to fibronectin and collagen IV but had no effect on attachment to laminin. By contrast, subsequent migration was significantly suppressed on all substrata. Our model permits the study of dynamic cell-cell and cell-extracellular-matrix interactions and indicates that RGDS might predominantly act on early tumor-cell locomotion after penetration of the endothelium.

Characterization of the new bladder cancer cell line HOK-1: expression of transitional, squamous and glandular differentiation patterns.

The new continuous cell line HOK-1 derived from a grade-III transitional-cell bladder carcinoma with foci of squamous and glandular differentiation was shown to retain this phenotypical heterogeneity for more than 45 passages in vitro. Electron microscopy revealed transitional as well as a considerable proportion of squamous carcinoma and adenocarcinoma cells. PAS-positive mucus was detected in numerous cells. These features were principally maintained when grown as multicellular spheroids and in nude mice. More pronounced signs of differentiation (i.e., expression of cytokeratins 10 and 11, formation of glandular structures) were found in xenograft tumours. Independently, cytokeratins 13, 18 and 19 were detected in vitro and in vivo, reflecting the urothelial origin. The line forms distinct colonies in soft agar, expresses Lewis-x and Lewis-y antigens and reacts with monoclonal antibodies (MAbs) against CEA, beta-HCG and URO-5. Cytogenetic analysis revealed several related clones with a rearrangement at chromosome 1 and loss of one X chromosome as common karyotypic changes in all clones. DNA content, as quantified by image analysis, showed a DNA stemline close to 2c. The new cell line HOK-1 can be used as an in vitro model to study the mechanisms of heterogeneous differentiation patterns in bladder cancer.