Susan M. Farmery

Expression of the antiapoptosis gene, Survivin, predicts death from recurrent colorectal carcinoma

BACKGROUND/AIMS Inhibition of programmed cell death (apoptosis) is associated with increased tumour aggressiveness, and expression ofSurvivin, an antiapoptosis gene, in colorectal carcinomas may provide important prognostic information. PATIENTS/METHODS Expression of Survivin messenger RNA was evaluated by reverse transcription-polymerase chain reaction in 144 colorectal carcinomas and 86 adjacent histologically normal mucosa samples from patients for whom long term follow up data were available. RESULTS Survivintranscripts were detected in a significantly greater proportion of carcinomas (63.5%) than normal mucosa samples (29.1%; p<0.001). The prevalence of Survivin expression was independent of advancing pathological stage. Death due to recurrent cancer following curative resection was predicted independently by tumour expression of Survivin (hazard ratio (HR) 2.60; 95% confidence interval (95% CI) 1.17–5.75) and lymph node metastases (HR 2.38; 95% CI 1.21–4.70). On stage wise analysis, the predictive value of Survivin expression was limited to patients with stage II colorectal carcinomas; those with Survivin negative tumours had a five year survival rate of 94.4% compared with 44.8% for patients withSurvivin positive tumours (p=0.004, log rank test). CONCLUSION In patients with stage II colorectal carcinomas,Survivin expression provides prognostic information that may have important therapeutic implications.

Gut barrier function in malnourished patients.

Background—The integrity of the gastrointestinal mucosa is a key element in preventing systemic absorption of enteric toxins and bacteria. In the critically ill, breakdown of gut barrier function may fuel sepsis. Malnourished patients have an increased risk of postoperative sepsis; however, the effects of malnutrition on intestinal barrier function in man are unknown. Aims—To quantify intestinal barrier function, endotoxin exposure, and the acute phase cytokine response in malnourished patients. Patients—Malnourished and well nourished hospitalised patients. Methods—Gastrointestinal permeability was measured in malnourished patients and well nourished controls using the lactulose:mannitol test. Endoscopic biopsy specimens were stained and morphological and immunohistochemical features graded. The polymerase chain reaction was used to determine mucosal cytokine expression. The immunoglobulin G antibody response to endotoxin and serum interleukin 6 were measured by enzyme linked immunosorbent assay. Results—There was a significant increase in intestinal permeability in the malnourished patients in association with phenotypic and molecular evidence of activation of lamina propria mononuclear cells and enterocytes, and a heightened acute phase response. Conclusions—Intestinal barrier function is significantly compromised in malnourished patients, but the clinical significance is unclear.

Death from early colorectal cancer is predicted by the presence of transcripts of the REG gene family.

An intrinsic component of colorectal carcinogenesis may be the capacity to activate regenerative responses simultaneously with inhibition of apoptosis. Since apoptosis is known to be inhibited in colorectal cancer, this study sought evidence for the activation of the REG family of genes which are considered to be activated during regeneration of intestinal mucosa. Transcripts for the REG gene were found in 53% of colorectal cancers and for the PAP gene in 60% of colorectal cancers, by RT-PCR. Using in situ hybridization, the REG transcripts were found to be present in the tumour cells themselves rather than inflammatory or stromal cells. There were no significant correlations between the expression of these two genes and tumour stage, age or sex of the patient population or tumour site. However, in patients with non-metastatic disease who underwent ostensibly curative surgery, the expression of REG alone and co-expression of REG with PAP had a highly significantly adverse effect on survival. These data provide support for the concept that, in some tumours, carcinogenesis involves a regenerative process which co-exists with apoptotic inhibition and may provide a valuable selective indicator of the need for adjuvant therapy in those patients with early-stage colorectal cancer whose disease is destined to recur after curative surgery.

Activated mesothelial cells produce heparin-binding growth factors: implications for tumour metastases.

Curative surgery for gastrointestinal malignancy is commonly thwarted by local tumour recurrence. The heparin-binding growth factors, basic fibroblast growth factor (bFGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF) and vascular epidermal growth factor (VEGF) are all implicated in the metastatic process, but whether or not these essential growth factors are produced by the activated peritoneum is unknown. This study reveals that peritoneal mesothelial cells constitutively express mRNA for bFGF, HB-EGF and two VEGF spliced variants, VEGF121and VEGF165. Mesothelial activation with interleukin (IL)-1b or tumour necrosis factor (TNF)-a produced an up-regulation of mRNA for HB-EGF and VEGF, but not bFGF expression. IL-6 failed to stimulate growth factor expression, whereas IL-2 produced a marked suppression in HB-EGF and bFGF, but not VEGF expression. Mesothelial cells were shown to predominantly express mRNA for the intermediate affinity (bgc) IL-2 receptor. Cytokine-induced growth factor up-regulation was confirmed at the protein level using Western blotting of mesothelial cell lysates for HB-EGF and culture supernatant enzyme-linked immunosorbent assay for VEGF. The production of these growth factors by human mesothelial cells may play a significant role in post-operative peritoneal tumour recurrence. Their common heparin-binding property offers a potential therapeutic target for manipulating the growth factor environment of the human peritoneum.

Somatostatin binding in normal and malignant human gastrointestinal mucosa

Somatostatin is a regulatory peptide implicated in the control of cellular proliferation in epithelial tissues and this regulation may occur directly via membrane bound receptor activation. The aim of this study was to investigate somatostatin binding in human gastrointestinal cancer and normal mucosa. Plasma membranes were prepared from specimens of tumour and normal mucosa from 51 patients undergoing surgical resection for malignancy (28 gastric, 23 colorectal). Using a competitive displacement assay, specific 125I-tyrosine-11-somatostatin-14 binding to plasma membranes was assessed and and characterised in terms of receptor affinity (Kd) and maximum binding capacity (Bmax) as determined by Scatchard analysis. Specific low affinity (Kd = 166 nM), high capacity (Bmax = 1.2 pmol mg-1 protein) somatostatin binding was demonstrated in 22 of the gastric cancers and 17 of the colorectal cancers (Kd = 140 nM, Bmax = 1.8 pmol mg-1 protein). Similar affinity and binding capacity was demonstrable in normal mucosal samples. High affinity receptors for somatostatin were expressed by one gastric carcinoma (Kd = 0.9 nM; Bmax = 0.23 pmol mg-1 protein). Thus, low affinity, high capacity binding is a common feature of gastrointestinal tumours and normal mucosa, and high affinity receptors may occasionally be demonstrated. The functional significance of these low affinity binding sites requires elucidation to determine whether long-acting somatostatin analogues may have therapeutic benefit in gastrointestinal malignancy.

Reversible Impairment in Monocyte Major Histocompatibility Complex Class II Expression in Malnourished Surgical Patients

BACKGROUND Upregulation of major histocompatibility complex (MHC) class II antigen in response to the T-cell lymphokine interferon-gamma (IFN-gamma) is central to T cell-macrophage cooperation and immune homeostasis. We evaluated this property in malnourished surgical patients and assessed the impact of nutrition repletion with total parenteral nutrition (TPN). METHODS Sixty-two patients were studied: 37 malnourished and 25 controls. Whole blood was cultured with or without IFN-gamma (100 U mL-1), dual-labeled with anti-CD14 (monocyte) and anti-human leukocyte antigen-DR antibodies and analyzed by flow cytometry. Phagocytosis was measured by flow cytometry. In a second study, 10 severely malnourished patients received 5 days of TPN and MHC class II expression was measured at the end of this period. RESULTS The magnitude of the increase in monocyte MHC class II expression in response to IFN-gamma was significantly increased in the control group compared with the malnourished group (107% vs 53%; p < .05). This impairment directly correlated with severity of malnutrition, but did not correlate with age or disease type. The number of bacteria phagocytozed per cell was significantly decreased (p < .05) in the malnourished group. In study 2, there was a significant increase in MHC class II induction with IFN-gamma after short-term TPN (58% before vs 173% after, p < .001). CONCLUSIONS MHC class II induction in response to IFN-gamma is significantly impaired in malnourished patients, correlating with the severity of malnutrition. This defect is reversed by short-term TPN. These data identify the reversible loss of a key mechanism, fundamental to host defense, that may enhance the risk of infection in malnourished patients.

Somatostatin binding in human gastrointestinal tissues: effect of cations and somatostatin analogues.

This study characterises the somatostatin binding site in human gastrointestinal cancer and mucosa in terms of cationic specificity and relative affinity for three somatostatin analogues. Competitive displacement assays were performed on plasma membranes from human gastric and colonic tissues using radiolabelled somatostatin-14 as ligand. Comparison was made with the somatostatin binding site in rat cerebral cortex. In gastrointestinal tissue, magnesium decreased and sodium increased specific binding. By contrast, in rat cerebral cortex, the converse cationic effect was seen. These changes resulted from alterations in receptor density, with no change in receptor affinity. Displacement studies were then performed with somatostatin-14 and somatostatin analogues RC-160, somatuline, and octreotide. RC-160 and somatuline displaced radiolabel from binding sites in gastric and colonic cancer and mucosa with 10-fold lower affinity than the native peptide. Octreotide did not displace radioligand in gastric or colonic cancer at any concentration tested. By contrast, in rat cortex, although all three analogues displaced with a lower affinity than the native peptide, there was no difference between analogues. These data suggest a distinct somatostatin receptor subtype in gastrointestinal tissues.

Host Responses to H. pylori

The interactions between Helicobacter pylori and the human gastric epithelium have been modeled in an in vitro cell culture system. The model permits investigation of the interplay between the bacteria and epithelial cells in a controled environment. Following coculture, the cells, bacteria, and culture supernatants are available for analysis.

Somatostatin and Human Gastrointestinal Cancer

In the UK colorectal cancer accounts for 11% of malignant neoplasms in men, and 10% in women. It is the second most common cause of cancer death in men, after carcinoma of the lung, and the third in women, after carcinoma of the breast and lung. Colorectal cancer is the commonest of gastrointestinal cancers and has a median 5 year survival rate of approximately 36%. Although carcinoma of the stomach has a lower incidence (6% in men and 4% in women) it is the fourth most common cause of cancer death in both men and women. It is the second commonest site of gastrointestinal malignancy and has a much poorer prognosis than colorectal cancer with a median five year survival of 11.1% in men and only 9.9% in women (Cancer Research Campaign, 1988-89). The prognosis for both of these conditions is primarily determined by the stage of disease at diagnosis and unfortunately the majority of patients present when the cancer has already invaded the serosal surface of the gut. For this reason it is clear that surgical treatment alone is inadequate.