Differential activation of the c-Ki-ras-2 proto-oncogene in human colorectal carcinoma.

In colorectal carcinoma, c-Ki-ras-2 mutations predominantly occur in codon 12 and, to a considerably lesser extent, in codon 13. To our knowledge, involvement of codon 61 in c-Ki-ras-2 has been reported only once among the large number of colon cancers investigated altogether. In this study, five human primary colorectal carcinomas were analyzed for the presence of activating c-Ki-ras-2 point mutations in codon 12, 13, and 61. Tumor DNAs were amplified by PCR and subsequently hybridized to a panel of synthetic oligonucleotides representing the complete spectrum of possible mutations. In two of the five tumors, mutations involving codons 13 and 61, respectively, were detected. These data extend previous findings that point mutation of codon 61 may be an improbable yet possible event leading to activation of c-Ki-ras-2 in colorectal carcinoma.

Increased expression of alpha6-integrin receptors and of mRNA encoding the putative 37 kDa laminin receptor precursor in pancreatic carcinoma.

The expression of alpha6-integrin receptors (VLA-alpha6) and of mRNA encoding the putative 37 kDa laminin receptor precursor (37 LRP) was determined in ductal pancreatic adenocarcinoma and normal pancreatic tissue from the same patient. VLA-alpha6 expression was enhanced and redistributed in pancreatic carcinoma, and 37 LRP mRNA levels were elevated in carcinomatous pancreatic tissue as well as in five pancreatic tumor cell lines. The molecular weight of the major RNA species detected was higher in carcinoma tissue (1.9 kb) as opposed to cell lines (1.2 kb), possibly reflecting alternative splicing of 37 LRP mRNA in the primary tumor.

The value of somatostatin-receptor scintigraphy in newly diagnosed endocrine gastroenteropancreatic tumors.

BACKGROUND: Conventional imaging techniques do not routinely detect endocrine gastroenteropancreatic tumors preoperatively. The purpose of this study was to determine whether the new technique of somatostatin-receptor scintigraphy would improve the detection rate of these tumors before initial treatment. STUDY DESIGN: In a prospective study, 55 patients with a recent diagnosis of endocrine gastroenteropancreatic tumors (22 intestinal carcinoids, 17 gastrinomas, 10 nonfunctioning pancreatic tumors, and 6 insulinomas), were examined with somatostatin-receptor scintigraphy, computed tomography, and ultrasonography. Results of the three imaging modalities were compared with findings at surgical exploration. RESULTS: None of the insulinomas were localized by somatostatin-receptor scintigraphy, but 4 of 6 insulinomas were detected by computed tomography and ultrasonography. Of 17 gastrinomas, 9 were detected by somatostatin-receptor scintigraphy; computed tomography and ultrasonography localized only 7. Metastases from the gastrinoma were localized by somatostatin-receptor scintigraphy in all cases; computed tomography and ultrasonography detected metastases in only 6 of 9 patients. Nonfunctioning tumors could be localized by somatostatin-receptor scintigraphy, computed tomography, and ultrasonography in 4, 7, and 8 of 10 cases, respectively. Detection rate for corresponding metastases was the same for all three imaging techniques. Primary carcinoids were identified by somatostatin-receptor scintigraphy, ultrasonography, and computed tomography in 7, 8, and 11 of 22 cases, respectively. Extra-abdominal metastases were detected by somatostatin-receptor scintigraphy in only 7 of 19 patients. CONCLUSIONS: In patients with insulinomas, somatostatin-receptor scintigraphy is not indicated because none of the six tumors was imaged. This holds true for nonfunctional pancreatic endocrine tumors and their metastases because no advantage for somatostatin-receptor scintigraphy was found over computed tomography and ultrasonography. In contrast, somatostatin-receptor scintigraphy is superior to computed tomography and ultrasonography for determining the extent of the disease in patients with gastrinomas or carcinoids. The problem of detecting primary tumors in these patients is not solved by somatostatin-receptor scintigraphy.

Expression and potential role of E-cadherin in pancreatic carcinoma.

CONCLUSION: Our results indicate that loss of E-cadherin might be associated with a more invasive phenotype in pancreatic cancer. BACKGROUND: A reduced expression of the calcium-dependent E-cadherin cell-cell adhesion molecule on tumor cells has been described as an important factor for tumor invasion and metastasis. METHODS: Pancreatic tissues (carcinoma, chronic pancreatitis, and normal) as well as 12 pancreatic tumor cell lines were investigated for E-cadherin expression by immunohistochemistry. To correlate the motility of pancreatic tumor cells in vitro with E-cadherin expression, we used a Boyden chamber assay. RESULTS: In pancreatic carcinoma tissues, diffuse growing tumor cells showed a decrease or loss of E-cadherin expression, whereas in areas of compact tumor growth, only a slight decrease of E-cadherin was observed compared to normal pancreas or chronic pancreatitis. No correlation between the E-cadherin expression and the grading of the tumor cells, the tumor stage, or the disease progression was detectable. Of four tumor cell lines that migrated in the Boyden chamber, three were predominantly E-cadherin negative. In contrast, seven of eight cell lines that did not migrate in vitro revealed E-cadherin expression.

Value of somatostatin receptor scintigraphy for preoperative localization of carcinoids.

Most carcinoid primary tumors are small and do not cause symptoms until complications (e.g. intestinal obstruction) or symptoms and signs of the carcinoid syndrome occur. Therefore in most cases an assessment of the primary tumor and its metastases must be performed. To determine the value of somatostatin receptor scintigraphy (SRS) for localizing carcinoid tumors, we compared the results of SRS with those obtained with computed tomography (CT) and ultrasonography (US) in 22 patients who had not undergone surgery for removal of the primary tumor. We could not find an advantage of SRS over CT and US for detecting the primary lesions. Tumors > 2 cm in diameter were regularly detected using all methods. SRS was not superior to CT or US for the detection of liver metastases. SRS showed the liver metastases in 16 of 18 patients, whereas CT and US detected liver metastases in all patients. For localization of extrahepatic abdominal and extraabdominal metastases (lymph nodes, bone), whole-body SRS showed an advantage over CT and US. We conclude that SRS is not superior to CT or US for localization of primary carcinoid tumors or liver metastases, although it did prove successful for visualizing extrahepatic and extraabdominal tumor spread. Additionally, SRS is useful for identifying receptor-positive metastases that may be treated by somatostatin analogs. Thus SRS should be performed in patients with a known carcinoid tumor, except those with an appendiceal carcinoid measuring < 1 cm in diameter.

Studies on tumor-cell-induced platelet aggregation in human lung cancer cell lines.

We investigated the ability of human lung cancer cells of different histological subtypes to cause platelet aggregation. Tumor-cell-induced platelet aggregation (TCIPA) was studied in vitro in 13 human lung cancer cell lines [small-cell lung cancer (SCLC), squamous-cell lung cancer, large-cell lung cancer, adenocarcinoma and alveolar-cell lung cancer]. Three tumor cell lines failed to aggregate platelets in platelet-rich plasma, whereas platelet aggregation was induced by 12 cell lines when added to washed platelets and minimal amounts of platelet-poor plasma (0.5% v/v). The thrombin antagonist hirudin inhibited TCIPA in non-small-cell lung cancer cell lines (NSCLC). In SCLC, TCIPA was fully abolished only when the ADP scavenger apyrase was added to hirudin. Thus ADP and thrombin generation by these tumor cell lines are responsible for platelet aggregation. The ability to activate platelets independently of coagulation factors VII and X was demonstrated for 8 cell lines. Electron-microscopically, direct tumor-cell/platelet contact was found to be the initiating mechanism of TCIPA in SCLC, whereas tumor-cell/platelet contacts in NSCLC could only be observed at the peak of the aggregation curve. Lung cancer cells activate platelets in vitro by generation of thrombin and/or ADP.

Tumor cell-induced platelet aggregation in vitro by human pancreatic cancer cell lines.

BACKGROUND: Tumor cell-induced platelet aggregation (TCIPA) is considered to be a critical step in hematogenous metastasis. METHODS: TCIPA was studied in vitro in six human pancreatic carcinoma cell lines (PC 3, PC 44, AsPC1, BxPC3, Capan2, Panc1). RESULTS: Whereas all cell lines induced aggregation of washed platelets in the presence of minimal amounts of platelet-poor plasma, five cell lines also induced aggregation of platelets in platelet-rich plasma. The thrombin-antagonist hirudin inhibited TCIPA in all cell lines indicating that TCIPA is thrombin-dependent. Since pretreatment of tumor cells with phospholipase A2 or C inhibited TCIPA, the thrombin-generating activity might be confined to the tumor cell surface. Further support for a prothrombinase activity was provided by the observation that all cell lines were able to induce the aggregation of washed platelets after addition of purified coagulation factors II and V. CONCLUSIONS: Pancreatic carcinoma cells are able to induce platelet aggregation via activation of thrombin. This might support metastasis in pancreatic cancer and possibly explain the incidence of thrombosis in this tumor.

The alpha 6-integrin receptor in pancreatic carcinoma.

BACKGROUND/AIMS: The alpha 6-containing integrin was suggested to be involved in the process of tumor invasion and metastasis. Therefore, the aim of the study was to investigate the expression and function of this adhesion receptor in pancreatic carcinoma. METHODS: Integrin expression was investigated in pancreatic tissue and tumor cell lines using immunohistochemistry. Radioimmunoprecipitation was used to determine the complex composition of alpha 6. To analyze the function of the alpha 6-containing integrin in pancreatic cancer, in vitro adhesion, migration, and invasion experiments were performed. RESULTS: The alpha 6-containing integrin was differentially expressed in normal pancreas and pancreatic carcinoma. Immunoprecipitation of different pancreatic carcinoma cell lines showed that alpha 6 was expressed together with the beta 4 subunit as alpha 6 beta 4 complex. However, adhesion of pancreatic cancer cells to laminin could be inhibited with anti-alpha 6 and anti-beta 1 integrin antibodies but not by anti-beta 4 integrin antibody. Migration of the cells through laminin was almost completely inhibited by anti-beta 1 antibody but not by other anti-integrin antibodies. Tumor cell invasion through a reconstituted basement membrane was only slightly inhibited by anti-alpha 6 antibody. In contrast, a marked inhibition was observed using anti-beta 1 antibodies, anti-alpha 2-anti-alpha 5 antibodies, and RGDS. CONCLUSIONS: The alpha 6-containing integrin is a laminin adhesion receptor in pancreatic carcinoma cells, possibly involved in tumor invasion through the basement membrane.

[Somatostatin receptor scintigraphy in preoperative diagnosis of the site of endocrine gastrointestinal tumors]. / Die Somatostatinreceptor-Szintigraphie in der präoperativen Lokalisationsdiagnostik endokriner gastrointestinaler Tumoren.

To determine the value of somatostatin-receptor scintigraphy in the localization of various endocrine gastrointestinal tumors, we compared the results obtained with this new technique with the results obtained with computed tomography and sonography. We could not find an overall advantage of somatostatin-receptor scintigraphy as compared to computed tomography or sonography in the localization of intestinal carcinoids (n = 13), gastrinomas (n = 12), functionally non-active endocrine pancreatic tumors (n = 8) and various other endocrine pancreatic tumors (n = 4). In 2 patients with endocrine pancreatic tumors however, the tumors were localized preoperatively only by somatostatin-receptor scintigraphy. Somatostatin-receptor scintigraphy may occasionally be helpful in the localization of gastrointestinal endocrine tumors if these tumors are not localized by conventional imaging studies. Somatostatin-receptor scintigraphy does not solve the problem to localize small endocrine tumors.

[54 consecutive duodenopancreatectomies without fatality]. / 54 konsekutive Duodenopankreatektomien ohne Letalität.

Over a five-year period (1.1.89-31.12.93), a duodenopancreatectomy (Whipple's operation) was performed without hospital or 30-day death in 54 consecutive patients (22 women, 32 men; mean age 62 [27-82] years). The postoperative morbidity was 39% (21 of 54 patients). The indications for the operation were malignant tumour (n = 41), mainly ductal adenocarcinoma of the pancreas (n = 30), benign tumour (n = 5) or inflammatory head of the pancreas tumour in chronic pancreatitis (n = 6). A classical Whipple's operation was performed in 36 patients, while the stomach-preserving variant was undertaken in 18. The main complications were postoperative disorders of gastric emptying (n = 13), bleeding (n = 7), abscess (n = 4), leakage at the pancreas anastomosis (n = 3) and pancreatic fistula (n = 2). All complications were successfully overcome by early use of interventional methods or relaparotomy. -The low mortality rate of Whipple's operation (0-5% in selected centres) justifies the use of this operation even in advanced malignancies.

Preoperative localization of gastrointestinal endocrine tumors using somatostatin-receptor scintigraphy.

OBJECTIVE: The purpose of this study was to determine the value of somatostatin-receptor scintigraphy (SRS) in the preoperative localization of gastrointestinal endocrine tumors. The authors report their preliminary experiences with this new technique as compared to conventional imaging studies like computed tomography (CT) and ultrasonography (US). SUMMARY BACKGROUND DATA: Most endocrine tumors possess high-affinity somatostatin-receptors. Using the stable, 111Indium labelled somatostatin analogue pentatreotid, which binds to these receptors, it is possible to detect somatostatin-receptor-positive tumors scintigraphically. METHODS: In nine patients with various gastrointestinal endocrine tumors, SRS, CT, and US were performed before surgical exploration. The preoperative imaging studies and intraoperative ultrasound (IOUS) were then compared to findings on surgical exploration. RESULTS: Twelve primary tumors were found in 8 patients at surgical exploration. These primary tumors were correctly identified with SRS in five patients, with US in four patients, and with CT in three patients. In one patient with the Zollinger-Ellison syndrome, scintigraphy suggested a tumor in the area of the hepatoduodenal ligament, while CT and US had negative results. The underlying gastrinoma could not be identified despite extensive surgical exploration. Scintigraphy, CT, and US showed comparable results in the detection of metastases in four patients. CONCLUSIONS: The data from this small series suggest that SRS is helpful in the preoperative localization of gastrointestinal endocrine tumors.

Expression and distribution of VLA receptors in the pancreas: an immunohistochemical study.

Very late activation (VLA) receptors mediate cell adhesion to extracellular matrix, mainly by acting as adhesion receptors to fibronectin, collagen, and laminin as well as to other cells. These interactions not only regulate normal cell-extracellular matrix contact, but also are thought to be involved in metastasis and invasive tumor growth. Using immunohistochemistry [the alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique] we compared the expression and distribution of VLA receptors in normal pancreatic tissue, chronic pancreatitis, and ductal pancreatic adenocarcinoma. Immunohistochemically, VLA alpha 2 and VLA alpha 6 were moderately to strongly expressed on the basal surface of ductal and acinar cells in normal pancreatic tissue, whereas centroacinar cells predominantly expressed VLA alpha 3 and VLA alpha 5. Similarly, pancreatic carcinoma showed an intensive staining for VLA alpha 2 and VLA alpha 6 with a diffuse distribution on the cell surface. Expression of VLA alpha 3 and VLA alpha 5 in pancreatic carcinoma was heterogeneous, ranging from moderate to weak and lost in about 50% of the cells. As our results suggest, cell-basement membrane interaction in ductal and acinar pancreatic cells is primarily mediated through VLA alpha 2 and VLA alpha 6, whereas VLA alpha 3 and VLA alpha 5 are the major VLA receptors on centroacinar cells. In pancreatic carcinoma a loss (VLA alpha 5) or redistribution (VLA alpha 2, VLA alpha 6) of VLAs was observed. This redistribution of VLA alpha 2 and VLA alpha 6 may reflect a loss of spatial arrangement of tumor cells and their ability to randomly interact with extracellular matrix structures during invasion and metastasis.

[Standardized surgical concept for the diagnosis and therapy of Zollinger-Ellison syndrome]. / Standardisiertes chirurgisches Konzept zur Diagnostik und Therapie des Zollinger-Ellison-Syndroms.

Between 1987 and 1991, 16 patients (13 females, three males; mean age 52.4 [33-73] years) with Zollinger-Ellison syndrome (ZES) were treated according to a standardized surgical concept. The diagnostic work-up consisted of measuring serum gastrin levels, pre-operative localization by ultrasound and abdominal computed tomography, as well as extensive staging by laparotomy. As complete a tumour resection as possible was the aim of treatment in 15 patients, while in one patient it was to reduce the tumour mass. In six patients who had resection of a solitary tumour there was no evidence of recurrence after 6-42 months of follow-up. Exploration of the duodenum made it possible to identify and then remove a small gastrinoma of the duodenal wall in three patients. No gastrinoma was found in one patient despite extensive exploration. In a further four patients the laparotomy was purely exploratory, because diffuse metastasization was found. In four patients the primary tumour and, where present, the regional lymph nodes were removed, but the signs of ZES persisted, i.e. the intervention was merely palliative. In one female patient, reduction of tumour mass was necessary because the symptoms could not be controlled by conservative measures: she died postoperatively from toxic hepatitis. This experience indicates that standardized surgical intervention achieves potentially curative results in nearly 40% of patients. Including the duodenum in the surgical exploration allows the identification of even small gastrinomas of the duodenal wall. It is concluded that all patients with ZES but no evidence of diffuse metastases should undergo surgical treatment.

Expression and function of VLA-alpha 2, -alpha 3, -alpha 5 and -alpha 6-integrin receptors in pancreatic carcinoma.

The expression of the VLA-integrins alpha 2, alpha 3, alpha 5 and alpha 6 was studied immunohistochemically in tissue samples from ductal pancreatic cancer, chronic pancreatitis, normal pancreas and in 8 cell lines of ductal human pancreatic cancer. Furthermore, adhesion assays on purified extracellular matrix (ECM)-compounds were used to define the function of alpha 2, alpha 3, alpha 5 and alpha 6 in pancreatic cancer cells. Immunohistochemically, VLA alpha 2 and VLA alpha 6 were moderately to strongly expressed on the basal surface of ductal and acinar cells in normal pancreatic tissue, while centro-acinar cells predominantly expressed VLA alpha 3 and VLA alpha 5. Pancreatic carcinoma showed intense staining for VLA alpha 2 and VLA alpha 6 with a diffuse distribution on the cell surface. The redistribution of VLA alpha 2 and VLA alpha 6 may reflect a loss of spatial arrangement of tumor cells and their ability to interact randomly with extracellular matrix structures during invasion and metastasis. Expression of VLA alpha 3 and VLA alpha 5 in pancreatic carcinoma was heterogeneous, ranging from moderate to weak, and was lost in about 50% of the cells. Two pancreatic carcinoma cell lines (PC 3, PC 44) were further investigated in adhesion assays. Monoclonal antibodies (MAbs) against alpha 2 (GI 9, 10-G-11) were able to inhibit tumor-cell adhesion to collagen IV (59%-72%) in both cell lines. A MAb against alpha 6 (GoH3) inhibited tumor-cell adhesion to laminin (52%-86%) in both cell lines. These results suggest that alpha 2 is a collagen-binding site and alpha 6 a laminin-binding site in pancreatic cancer cells. The anti-alpha 5-MAb SAM I inhibited adhesion of PC3 to fibronectin (76%), being without effect in PC44. Adhesion of both cell lines to fibronectin was almost completely inhibited by RGDS (85%-88%). Thus, alpha 5 is a functionally important fibronectin binding site in some pancreatic carcinoma cells, suggesting further RGD-dependent fibronectin binding sites in other pancreatic carcinoma cells.

Frequent loss of expression of the potential tumor suppressor gene DCC in ductal pancreatic adenocarcinoma.

The development of colon carcinomas is associated with allelic deletions on chromosomes 5q, 17p, and 18q. The DCC gene located on chromosome 18q21.3 codes for a potential tumor suppressor gene related to cellular adhesion receptors. We investigated the expression of this gene in several pancreatic carcinoma cell lines and in patients with ductal adenocarcinomas of the pancreas. In 8 of 11 cell lines and in 4 of 8 primary tumors a complete extinction of DCC gene expression was observed, whereas the c-Ki-ras gene was mutated at codon 12 in 7 of 8 tumors. A highly reduced or absent expression of DCC was found in all low or undifferentiated pancreatic tumor cell lines, whereas in the more differentiated ones DCC expression was conserved. These data suggest that loss of DCC gene expression is an important factor in the development or progress of pancreatic adenocarcinoma and may be linked to the differentiated phenotype of the pancreatic tumor cell.

[Somatostatin in preoperative therapy and postoperative diagnosis of a patient with Verner Morrison syndrome]. / Somatostatin in der präoperativen Therapie und postoperativen Diagnostik eines Patienten mit Verner-Morrison-Syndrom.

We report the case of a patient with Verner-Morrison syndrome due to a malignant MEN I-associated vipoma. Marked tumor-associated hypercalcemia could be treated successfully with somatostatin analogues prior to surgical therapy of the pancreatic tumor. Sixteen months after extirpation of the primary tumor recurrent tumor growth was diagnosed; at this time the patient was clinically asymptomatic and had no abnormal laboratory test results. Liver metastases and local metastases were identified using somatostatin receptor scintigraphy. We report and discuss the use of somatostatin in the treatment of tumor-associated symptoms in endocrine tumors and the possibility of identifying endocrine tumors by means of somatostatin receptor scintigraphy.