ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Mutations at codon 12 of the K-rasgene have been detected in pancreatic adenocarcinomas by a variety of techniques. A few of these techniques are very sensitive, identifying the mutations in 96–100% of cases. However, these sensitive techniques are labor intensive, utilizing multistep processing and radioactive material. Much simpler techniques, involving nonradioactive single-step polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) have been employed to detect K-rasmutations at codon 12 in pancreatic adenocarcinomas. However, the low sensitivity of these single-step PCR/RFLP techniques is unacceptable. A simple and nonradioactive PCR/RFLP-based method for detection of K-rascodon 12 mutations in formalin-fixed, paraffin-embedded tissue sections of pancreatic adenocarcinoma is described and compared to the traditional PCR technique. K-rasgene mutations at codon 12 were detected by a modified two-step enrich-nested PCR (EN-PCR)/RFLP method, and their existence was confirmed by direct DNA sequencing analysis of the product. When the two-step EN-PCR/RFLP technique was compared to the single-step PCR/RFLP method, K-rascodon 12 mutations were detected in 100% of pancreatic adenocarcinomas (15/15) with the EN-PCR/RFLP method, while half as many (9/15) were detected with the single-step PCR/RFLP method. This study demonstrates that the sensitivity of the simple two-step EN-PCR/RFLP technique is comparable to that of the more complex methods for detecting K-rasmutations at codon 12 in formalin-fixed, paraffin-embedded tissue sections of pancreatic adenocarcinoma and its sensitivity is superior to that of the single-step technique.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Pancreatic cancer is the fifth leading cause of cancer death in the United States. Most patients have obvious metastases or locally advanced disease at the time of presentation. Surgical resection does not significantly change the clinical outcome. Combination chemotherapy induces a partial response but overall survival remains low. The aim of this study was to evaluate the feasibility of adenovirus-mediated suicide gene transduction as a therapeutic approach for pancreatic cancer. A cell line was established from a murine pancreatic ductal adenocarcinoma and intrahepatic tumors were generated by inoculation of pancreatic cancer cells into the left lateral liver lobe. Transduction efficiency was characterized in vitro and in vivo. Intrahepatic tumors were treated by intratumoral adenovirus injection in combination with intraperitoneal administration of ganciclovir. Adenovirus-mediated herpes simplex virus (HSV)-thymidine kinase (tk) gene expression followed by ganciclovir treatment was highly efficient in inhibiting pancreatic cancer cell proliferation in vitro. The proliferation of nontransduced cells was significantly reduced in the presence of HSV-tk expressing cells. Intrahepatic inoculation of pancreatic cancer cells leads to successful formation of solid adenocarcinomas in syngeneic recipients. Ad.RSV-tk injection of the tumor followed by intraperitoneal ganciclovir application caused highly significant tumor volume reduction and necrosis. These results indicate that transduction of the HSV-tk gene followed by ganciclovir is highly efficient for growth inhibition of hepatic metastases of pancreatic carcinoma.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Hepatocyte growth factor (HGF) is a widely expressed growth factor secreted by cells of mesenchymal origin, which has been shown to be involved in growth processes of multiple cell types. The HGF receptor, the product of the c-metprotooncogene, is expressed mainly by epithelial cells. Increased expression of the HGF receptor has been observed in various tumors. To investigate the expression of the HGF receptor in the pancreas, we analyzed rat and human normal tissue and pancreatic carcinoma by Western blot analysis. We observed weak expression of c-metreactivity in normal pancreas but markedly enhanced expression in both rat and human pancreatic cancer. To test the possibility that HGF could act as a growth factor on pancreatic carcinoma, the effects of HGF on DNA synthesis in a rat and two human pancreatic carcinoma cell lines were analyzed. HGF induced dose-dependent [3H]thymidine incorporation, reaching 320, 210, and 180% above unstimulated controls in AR4–2J, PancTu-1, and 818/4 cells, respectively. The activation of signal transduction pathways by HGF was further analyzed in AR4–2J cells. After stimulation, a rapid and intense increase in receptor tyrosine phosphorylation was detected. Furthermore, HGF induced a time- and dose-dependent induction of c-fosexpression. The addition of tyrphostin, a specific tyrosine kinase inhibitor, prevented c-fosinduction and inhibited HGF-induced [3H]thymidine incorporation. In summary, our results demonstrate strongly increased HGF receptor expression in pancreatic carcinoma and support the assumption that HGF could act as a growth promoting factor on this cancer via stimulation of tyrosine kinases.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Pancreatic neoplasms harbor different prognoses according to their histological type: a benign course for serous cystadenoma, a low malignant potential for intraductal papillary mucinous neoplasms (IPMN), and high aggressiveness for ductal adenocarcinoma (ADC). Transforming growth factor β1(TGFβ1) may regulate tumor growth. The present study analyzes and compares the expression of its precursor β1-latency-associated peptide (β1LAP), its latent binding protein (LTBP), and its mRNA in ductal adenocarcinoma (n= 10), in IPMN (n= S), in serous cystadenoma (n= 2), and in normal tissues (n= 5). LTBP is thought to play a strategic role in the processing and active secretion of latent TGFβ1and its stockage in the extracellular matrix. Localization of β1-LAP and LTBP was assessed by immunohistochemistry using specific antibodies and expression of TGFβ1mRNA by reversetranscriptase polymerase chain reaction analysis. β1-LAP was only slightly expressed in normal specimens, while LTBP was not detected. β1-LAP was detected in the cytoplasm of neoplastic cells in 9 of 10 patients with ADC. An intense staining was present in stromal cells surrounding the neoplastic glands in all cases except in one carcinoma in situ. LTBP was detected only in stromal cells and in the surrounding extracellular matrix. In IPMN with mild-grade dysplasia and in cystadenoma, β1-LAP was strongly expressed in the epithelial cells, while it was poorly detected in invasive IPMN; stromal cells were poorly or not all stained by β1-LAP, except in invasive IPMN (n= 2). LTBP was detected in neoplastic cells of three cases with benign IPMN and two of two cases with cystadenoma, while stroma was not immunostained. TGFβ1mRNA was strongly expressed in most of the tumors and no difference in expression was observed between the different types of neoplasms. There is no quantitative difference in expression of TGFβ1in ADC and in IPMN or cystadenoma. However, the latter are able to secrete TGFβ1efficiently, in contrast to ductal ADC as shown by the ability of the neoplastic cells to express both β1-LAP and LTBP. Invasive stroma reaction was associated with enhanced β1-LAP and LTBP expression in stromal cells and could be mediated by TGFβ1via LTBP.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Tissue specimens of the normal pancreata from three adult patients were subjected to serial sectioning and computer-assisted three-dimensional reconstruction of the lobules, blood vessels, pancreatic ducts, and islets, to establish the anatomical relation among these structures. Most lobules, although more or less imperfectly demarcated by septa, were found to receive a single duct (lobular duct), justifying their definition as “glandular lobules.” However, there were also lobules receiving not only a lobular duct of their own but a small accessory duct from a neighboring lobule. On the other hand, these lobules were shown not to correspond to the territories of arterial supply, leaving no ground for defining them as “vascular lobules.”

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

We studied the effect of aging on B-cell function and replication in depancreatized rats. Male Wistar rats, at the ages of 1, 5, and 15 months, underwent 90% pancreatectomy (Px) or a sham operation, and islet function and regeneration were examined 3 weeks later. Plasma glucose levels in 1-month-old rats reached a peak 2 weeks after Px and then declined, while those in 5- and 15-month- old rats reached significant levels as early as the day after Px or 2 days after surgery and continued to increase over the following 3 weeks. Consequently, in contrast to young Px rats, weight loss due to severe diabetes was observed in 5- and 15-month-old Px rats. Plasma glucose responses to intravenous glucose loading (0.5 g/kg body weight) were much greater in older Px rats than in younger rats. There was a marginal insulin response to glucose in 1-month-old Px rats, whereas no insulin response to glucose was observed in older Px animals. The insulin content of the residual pancreas was increased threefold in 1-month-old Px rats, but there was no increase in 5- and 15-month-old Px rats. These data demonstrate that the effect of reducing islet mass is much greater in aged rats than in young rats and that the replicatory capacity of B cells tends to diminish after adulthood has been reached.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The diabetes or impaired glucose tolerance that occurs in most patients with pancreatic cancer is characterized by profound insulin resistance. Recent evidence suggests that the diabetes may result from the presence of the tumor rather than being a predisposing factor to development of the malignancy. Some islet hormones have been shown to exhibit diabetogenic effects. To investigate the potential role of these hormones in the diabetic state associated with pancreatic cancer, we measured islet hormones during fasting in pancreatic cancer patients (n= 30), patients with other malignancies (n= 43), and healthy controls (n= 25). Preoperative pancreatic cancer patients were classified as normal glucose tolerance (NGTT), impaired glucose tolerance (IGTT), non-insulin-requiring diabetes (NIRD), and insulin-requiring diabetes (IRD). Nine pancreatic cancer patients were studied after tumor removal by subtotal pancreatectomy. Some preoperative pancreatic cancer patients (n= 19), postoperative patients (n= 9), and controls (n= 8) were also studied during hyperglycemia and following glucagon injection. Fasting plasma C-peptide was elevated in NIRD pancreatic cancer patients compared to controls. Fasting levels of islet amyloid polypeptide (IAPP), glucagon. and somatostatin were elevated in NIRD and IRD patients. IAPP and glucagon, but not somatostatin, normalized following subtotal pancreatectomy. During hyperglycemia, increases in C-peptide and IAPP were seen only in controls and in NGTT and postoperative pancreatic cancer patients. After glucagon infusion, IAPP levels increased in controls and nondiabetic cancer patients; C-peptide levels increased in controls, nondiabetic patients, and NIRD. Responses of C-peptide and IAPP to glucagon normalized after pancreatectomy. During hyperglycemia, glucagon levels fell in all groups except IGTT patients and a decrease in somatostatin concentrations was seen in controls.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Retinol or retinoic acid is required for insulin release. Retinoids increase transglutaminase activity, and transglutaminase has been implicated in islet insulin release. To examine whether transglutaminase could mediate effects of retinoids on insulin secretion, we measured (i) transglutaminase activity in islets from rats deficient in vitamin A or repleted with retinol or retinoic acid, (ii) transglutaminase activity in RINm5F and INS-1 insulin-secreting cells cultured in retinol or retinoic acid, (iii) mRNA for transglutaminase in RINm5F and INS-1 cells, and (iv) insulin secretion from INS-1 cells in response to retinoic acid. Islets from rats repleted with retinol or retinoic acid showed more than twice the transglutaminase activity of islets from vitamin A-deficient rats. Retinoic acid increased RINm5F cells and INS-1 cell transglutaminase activity. Retinol did not increase transglutaminase activity. Transglutaminase mRNA was detected in INS-1 cells but not in RINm5F cells. Retinoic acid increased insulin secretion from INS-1 cells as observed previously in RINm5F cells. In conclusion, retinoic acid increases transglutaminase activity in both rat islets and two insulin-secreting cell lines. Retinoic acid stimulates insulin secretion from INS-1 cells. Transglutaminase is a candidate for mediating retinoid-induced changes in insulin secretion.

ISSN:0885-3177    

出版商:OVID    

年代:1997

数据来源: OVID