M. C. A. Puntis

Inhibition of hepatocyte growth factor-induced motility and in vitro invasion of human colon cancer cells by gamma-linolenic acid.

In this study we have determined the effects of the n-6 essential fatty acid gamma-linolenic acid (GLA) on the motility and invasive/metastatic nature of the human colon cancer cell lines HT115, HT29 and HRT18. Cell motility was induced by hepatocyte growth factor/scatter factor (HGF/SF) and measured by both colony scattering and dissociation from carrier beads. Invasiveness was measured in vitro by cellular invasion into extracellular matrix. At concentrations up to 100 microM (which had no effect on cell growth over the duration of the experiments) both cell motility and invasion induced by HGF/SF were markedly reduced by GLA and its lithium salt. The attachment of these cells to the extracellular matrix components (Matrigel and fibronectin) was also inhibited. There were also changes in the cell-surface E-cadherin, but not fibronectin receptor at similar concentrations. It is concluded that n-6 essential fatty acids have the ability to inhibit both motility and invasiveness of human colon cancer cells, perhaps by modifying cell-surface adhesion molecules.

Regulation of spreading and growth of colon cancer cells by hepatocyte growth factor

Hepatocyte growth factor (HGF), also known as scatter factor, regulates both cell motility and the growth of some cell types. We have determined the effects of HGF on the motility and growth of human colon cancer cell lines (HT115, HT29, HRT18 and HT55). Cell motility, as measured by dissociation from carrier beads or by scattering of cell colonies, was greatly increased in all cell lines. The effects were completely blocked by anti-HGF antibody. In contrast, cell growth of HT115, HT29 and HRT18 cells was inhibited by a wide range of concentrations of HGF. HT55 cell growth was also inhibited but needed a prolonged culture period (>5 days). The HGF receptor/Met protein is highly expressed in the membrane fraction of these cells as determined by Western blotting. It is concluded that HGF has an effect on both colon cancer cell motility and growth, which may be important in the control of the spread of colon cancer.

Expression of the HGF/SF receptor, c-met, and its ligand in human colorectal cancers

The c-met proto-oncogene product is a receptor tyrosine kinase that mediates the effects of the multifunctional cytokine hepatocyte growth factor/scatter factor (HGF/SF). We have studied the expression of both the c-met receptor and HGF/SF at both the protein and message level in colorectal cancer tissues of varying disease stage. All of the tumors displayed an overexpression of the c-met mRNA compared to their normal tissue counterparts while 16 of 21 tissues (75%) displayed up-regulation of c-met protein. No HGF/SF mRNA or protein could be detected in either tissue type. Viable tumor cells extracted from cancer tissue exhibited increased motility in response to HGF/SF stimulation demonstrating that c-met was functionally active. No correlation between expression of c-met and tumor stage or degree of differentiation was observed. HGF/SF is known to be a potent stimulator of tumor cell motility and invasion, two cellular properties essential for the metastatic development of cancers. The overexpression of the HGF/SF receptor in colorectal cancers may result in an increased sensitivity to HGF/SF, which may confer an enhanced metastatic potential to the cancer cells within the tumor body.

Plasma cytokine levels and monocyte activation in patients with obstructive jaundice.

Some monocytic cytokines are important immune regulators. We have investigated cytokine production by monocytes and the blood levels of IL‐1β, IL‐6, TNFα, and TGFβ, in patients with obstructive jaundice. The supernatant from LPS stimulated monocytes from jaundiced patients released significantly increased quantities of TNFα by both bioassay and radioimmunoassay (RIA) (12.4 ± 2.5 fmol/mL and 32.6 ± 8.3 fmol/mL, respectively, for jaundice, compared with 1.6 ± 0.3 fmol/mL and 2.4 ± 0.5 fmol/mL respectively for controls, and also of IL‐6 (54.8 ± 5.0 fmol/mL in jaundice compared with 35.6 ± 5.0 fmol/mL for controls). The production of IL‐1β and TGFβ by stimulated monocytes was unchanged. Jaundiced patients had significantly higher plasma TGFβ, but TNFα and IL‐1β were below the limits of detection. The highest monocyte TNFα and IL‐6 levels were seen in malignant disease patients, especially those with a poor immediate prognosis. We conclude that the production of some cytokines by monocytes is up‐regulated in patients with obstructive jaundice.

Neutrophil priming by cytokines in patients with obstructive jaundice

Patients with obstructive jaundice frequently suffer postoperative complications. We have investigated the relationship of obstructive jaundice to the neutrophil oxidase response and the “priming” of the response by the cytokines TNFα, interleukin-1 (IL-1), IL-6, and IL-8. On stimulation with f-met-leuphe (fmlp), the respiratory burst in neutrophils from jaundiced patients was greatly increased compared with controls (p < 0.01), jaundiced patients having the highest respiratory burst levels were those with the poorest prognosis. Neutrophils from controls were primed by all the cytokines tested, whereas “jaundiced” cells were primed only by IL-1, and not by TNFα, IL-6, or IL-8, which in fact produced slight inhibition. We conclude that neutrophils from obstructive jaundiced patients have raised oxidative responses which may be due to “pre-priming” in vivo by cytokines, such as IL-6, IL-8, or TNFα. This exaggeration of the oxidative response in circulating neutrophils may contribute to the peri-operate complications of patients with obstructive jaundice.

Selenium Deficiency and Chronic Pancreatitis:Disease Mechanism and Potential for Therapy

Background: It has been suggested that antioxidant deficiency may play a role in the pathogenesis of chronic pancreatitis. The aim of this review was to analyse the evidence for this relationship and to consider the role of antioxidant supplementation in the treatment of chronic pancreatitis. Methods: Medline review of all English language publications for the years 1966–1998. Results and Conclusions: There is evidence that patients with chronic pancreatitis have enhanced levels of free radical production, cytochrome P450 induction and antioxidant deficiencies, in particular selenium. The limited published literature in this field suggests that dietary antioxidant supplementation may ameliorate the pain associated with chronic pancreatitis, diminish the frequency of acute exacerbations and reduce the requirement for pancreatic surgery. These findings await confirmation by a large prospective placebo-controlled study.

Regulation of desmosomal cell adhesion in human tumour cells by polyunsaturated fatty acids

Desmosomes are key structures in cell-cell adhesion. In this study we examined the effect of n-6 essential fatty acids on the expression of desmoglein (Dsg), desmosomal cadherin and the formation of desmosomes in E-cadherin negative human breast, colon and lung cancer cells and melanoma cells. Electron microscopy revealed that cells cultured with gamma linolenic acid (GLA) showed increased cell-cell adhesion together with an increase in the formation of desmoglein-containing desmosomes. Western blotting studies of cellular proteins demonstrated that, following culture with fatty acids, Dsg expression was modified, with the greatest increase seen after GLA treatment. Other fatty acids increased Dsg expression, but to a lesser extent. It is concluded that GLA regulates desmosome-mediated cell-cell adhesion in human cancer cells, particularly in cells without E-cadherin.

Selective Use of Endoscopic Ultrasound in the Evaluation of Carcinomas of the Pancreatic Head

Background: The aims of this study were to assess the role of endoscopic ultrasound (EUS) in the evaluation of adenocarcinoma of the head of the pancreas in cases of diagnostic dilemma and to determine the strength of agreement between perceived pre-operative stage as determined by computerised tomography (CT) and EUS and histopathological stage. Methods: Patients undergoing pancreatic EUS were identified from a computerised radiology database. The strengths of agreement between the radiological and histopathological stages were determined by the weighted kappa (Kw) statistic. Results: Fifty-eight patients were identified. Of 37 patients with a pancreatic head mass on prior imaging, 32 had a diagnosis of adenocarcinoma confirmed by EUS, as did 11 of 21 patients with suspicious pancreatic head lesions. Twenty-five of 43 patients were deemed to have resectable carcinomas, and 2 patients had resectable mucinous lesions. In comparing CT and EUS in the 25 patients undergoing resection, the Kw for T and N stages was 0.250 (p = 0.05) and –0.080 (p = 0.288), respectively, for CT, compared with 0.738 (p = 0.0001) and 0.606 (p = 0.0001), respectively, for EUS. Conclusions: EUS was effective in assessing the resectability of pancreatic head adenocarcinomas. Furthermore, EUS held a significant 3-fold advantage over CT with regard to T stage and an even higher significant advantage with regard to N stage.

Monocyte and blood interleukin-12 levels in patients with obstructive jaundice.

Patients with obstructive jaundice have an increased incidence of peri-operative complications and immune dysfunction. This study was to investigate interleukin (IL)-12 (a cellular immunity stimulant), levels in jaundiced patients. 23 jaundiced patients and 17 controls were studied. There was significantly increased monocyte IL-12 production in jaundice, as measured by an ELISA, compared with that in controls (p<0.01 by Mann-Whitney U test). A similar increase is seen in both benign and malignant jaundice. There was no difference between plasma IL-12 levels in the two groups. It is concluded that in jaundice, monocytes have a significantly increased capacity to release IL-12. This suggests that IL-12 may play a role in the immune dysfunction in jaundiced patients.

Monocyte secretion of beta-hexosaminidase in patients with obstructive jaundice

Monocyte hydrolases are harmful when secreted inappropriately. In this study we have investigated the levels of one of the hydrolases, β-hexosaminidase in patients with obstructive jaundice. These patients showed markedly elevated plasma levels, and their monocytes show increased spontaneous secretion and total enzyme content. The plasma enzyme levels correlate with monocyte enzyme content as well as bile salt, and bilirubin levels, the high levels may also reflect Kupffer cell damage, as these cells clear the enzyme. Compared with controls monocytes from jaundiced patients show reduced enzyme secretion after PMA stimulation, in vitro, and unchanged secretion after zymozan stimulation. There is a difference between plasma enzyme levels in benign and malignant patients but this does not provide a clear distinction between the two groups. We conclude that patients with obstructive jaundice have increased blood level of β-hexosaminidase, and that activated monocytes partly contribute to this change.