Patrizia Cohen

MicroRNAs targeting oncogenes are down-regulated in pancreatic malignant transformation from benign tumors.

Background MicroRNA (miRNA) expression profiles have been described in pancreatic ductal adenocarcinoma (PDAC), but these have not been compared with pre-malignant pancreatic tumors. We wished to compare the miRNA expression signatures in pancreatic benign cystic tumors (BCT) of low and high malignant potential with PDAC, in order to identify miRNAs deregulated during PDAC development. The mechanistic consequences of miRNA dysregulation were further evaluated. Methods Tissue samples were obtained at a tertiary pancreatic unit from individuals with BCT and PDAC. MiRNA profiling was performed using a custom microarray and results were validated using RT-qPCR prior to evaluation of miRNA targets. Results Widespread miRNA down-regulation was observed in PDAC compared to low malignant potential BCT. We show that amongst those miRNAs down-regulated, miR-16, miR-126 and let-7d regulate known PDAC oncogenes (targeting BCL2, CRK and KRAS respectively). Notably, miR-126 also directly targets the KRAS transcript at a “seedless” binding site within its 3′UTR. In clinical specimens, miR-126 was strongly down-regulated in PDAC tissues, with an associated elevation in KRAS and CRK proteins. Furthermore, miR-21, a known oncogenic miRNA in pancreatic and other cancers, was not elevated in PDAC compared to serous microcystic adenoma (SMCA), but in both groups it was up-regulated compared to normal pancreas, implicating early up-regulation during malignant change. Conclusions Expression profiling revealed 21 miRNAs down-regulated in PDAC compared to SMCA, the most benign lesion that rarely progresses to invasive carcinoma. It appears that miR-21 up-regulation is an early event in the transformation from normal pancreatic tissue. MiRNA expression has the potential to distinguish PDAC from normal pancreas and BCT. Mechanistically the down-regulation of miR-16, miR-126 and let-7d promotes PDAC transformation by post-transcriptional up-regulation of crucial PDAC oncogenes. We show that miR-126 is able to directly target KRAS; re-expression has the potential as a therapeutic strategy against PDAC and other KRAS-driven cancers.

Divergent Effects of Liraglutide, Exendin-4, and Sitagliptin on Beta-Cell Mass and Indicators of Pancreatitis in a Mouse Model of Hyperglycaemia

Aims Glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP4) inhibitors improve glucose tolerance by still incompletely understood mechanisms. Each class of antihyperglycemic drugs has also been proposed to increase pancreatitis risk. Here, we compare systematically the effects of two widely-used GLP-1 analogues, liraglutide and exendin-4, and the DPP4 inhibitor, sitagliptin, in the mouse. Methods C57BL6 mice were maintained for 131 days on a normal diet (ND) or a diet comprising 60% fat (HFD) before measurements of fasting blood glucose and insulin, and intraperitoneal glucose tolerance. Beta- and alpha- cell volume, and Reg3b immunoreactivity, were measured by immunohistochemical analysis of pancreatic slices. Results Whereas liraglutide (200 µg/kg) and exendin-4 (10 µg/kg) treatment reduced body weight and/or improved glucose tolerance, sitagliptin (10 mg/kg) was without effect on either parameter. Liraglutide caused a sharp reduction in beta-cell mass in both ND and HFD mice, whereas exendin-4 exerted no effect. By contrast, sitagliptin unmasked an action of high fat diet to increase beta-cell mass. Reg3B positive area was augmented by all three agents in normal chow-fed mice, whilst sitagliptin and exendin-4, but not liraglutide, affected this parameter in HFD animals. Correspondingly sitagliptin, but not the GLP-1 analogues, increased circulating amylase levels in ND and HFD mice. Conclusions Liraglutide improves glucose tolerance in the mouse whilst exerting relatively modest effects on pancreatitis risk. Conversely, exendin-4 and sitagliptin, at doses which exert, respectively, minor or no effects on metabolic parameters, lead to signs of pancreatitis.

Growth arrest-specific transcript 5 associated snoRNA levels are related to p53 expression and DNA damage in colorectal cancer

Background The growth arrest-specific transcript 5 gene (GAS5) encodes a long noncoding RNA (lncRNA) and hosts a number of small nucleolar RNAs (snoRNAs) that have recently been implicated in multiple cellular processes and cancer. Here, we investigate the relationship between DNA damage, p53, and the GAS5 snoRNAs to gain further insight into the potential role of this locus in cell survival and oncogenesis both in vivo and in vitro. Methods We used quantitative techniques to analyse the effect of DNA damage on GAS5 snoRNA expression and to assess the relationship between p53 and the GAS5 snoRNAs in cancer cell lines and in normal, pre-malignant, and malignant human colorectal tissue and used biological techniques to suggest potential roles for these snoRNAs in the DNA damage response. Results GAS5-derived snoRNA expression was induced by DNA damage in a p53-dependent manner in colorectal cancer cell lines and their levels were not affected by DICER. Furthermore, p53 levels strongly correlated with GAS5-derived snoRNA expression in colorectal tissue. Conclusions In aggregate, these data suggest that the GAS5-derived snoRNAs are under control of p53 and that they have an important role in mediating the p53 response to DNA damage, which may not relate to their function in the ribosome. We suggest that these snoRNAs are not processed by DICER to form smaller snoRNA-derived RNAs with microRNA (miRNA)-like functions, but their precise role requires further evaluation. Furthermore, since GAS5 host snoRNAs are often used as endogenous controls in qPCR quantifications we show that their use as housekeeping genes in DNA damage experiments can lead to inaccurate results.

The McKittrick-Wheelock syndrome: A case of acute renal failure due to neoplastic cholera

The McKittrick Wheelock syndrome is characterized by severe electrolyte and fluid depletion as a result of rectal tumor hypersecretion. Typically, a metabolic acidosis ensues. We report the case of a 58-year-old man who presented with a mixed metabolic acidosis and alkalosis. He was hyponatremic, hypokalemic, and hypochloremic, with acute renal failure on blood testing. Following fluid resuscitation, a predominant alkalemia was observed. The patient was found to be passing 1.5 L of mucous per rectum per day, containing high concentrations of sodium and potassium, similar to that observed in cholera stool. A large rectal villous adenoma was discovered on sigmoidoscopy, and definitive management was achieved by removal of the tumor. This case provides a demonstration of the ranging metabolic disturbance associated with secretory diarrhea. Other endogenous and infective causes are discussed, and mechanisms compared with the case described.

Poorly-Differentiated Signet-Ring Cell Carcinoma of the Ampulla of Vater: Report of a Rare Malignancy

CONTEXT Signet-ring cell carcinoma (SRCC) of the ampulla of Vater is a very rare clinical entity, which is infrequently reported in medical literature. CASE REPORT A 78-year-old woman was admitted with jaundice, pruritus and postprandial vomiting. Abdominal ultrasound and computed tomography scanning demonstrated gross dilatation of the common bile and pancreatic ducts with gallbladder calculi. Endoscopic retrograde cholangiopancreatography suggested a duodenal tumour at the ampulla. The patient underwent Whipples procedure with cholecystectomy. Immunohistopathological examination confirmed poorly-differentiated SRCC of the ampulla of Vater. The tumour had infiltrated the duodenal muscularis propria and pancreatic parenchyma, but local lymph nodes were clear (T3N0M0). The patient was disease-free at 6-month follow-up. CONCLUSIONS We here report a case of poorly-differentiated SRCC of the Ampulla of Vater. The majority of patients with such tumours undergo pancreaticoduodenectomy, which affords good outcomes in early disease. However, owing to the rarity of cases, the exact prognosis of ampullary SRCC remains as yet undetermined.

Glucagon receptor gene mutations with hyperglucagonemia but without the glucagonoma syndrome.

Pancreatic neoplasms producing exclusively glucagon associated with glucagon cell hyperplasia of the islets and not related to hereditary endocrine syndromes have been recently described. They represent a novel entity within the panel of non-syndromic disorders associated with hyperglucagonemia. This case report describes a 36-year-old female with a 10 years history of non-specific abdominal pain. No underlying cause was evident despite extensive diagnostic work-up. More recently she was diagnosed with gall bladder stones. Abdominal ultrasound, computerised tomography and magnetic resonance imaging revealed no pathologic findings apart from cholelithiasis. Endoscopic ultrasound revealed a 5.5 mm pancreatic lesion. Fine needle aspiration showed cells focally expressing chromogranin, suggestive but not diagnostic of a low grade neuroendocrine tumor. OctreoScan(®) was negative. Serum glucagon was elevated to 66 pmol/L (normal: 0-50 pmol/L). Other gut hormones, chromogranin A and chromogranin B were normal. Cholecystectomy and enucleation of the pancreatic lesion were undertaken. Postoperatively, abdominal symptoms resolved and serum glucagon dropped to 7 pmol/L. Although H and E staining confirmed normal pancreatic tissue, immunohistochemistry was initially thought to be suggestive of alpha cell hyperplasia. A count of glucagon positive cells from 5 islets, compared to 5 islets from 5 normal pancreata indicated that islet size and glucagon cell ratios were increased, however still within the wide range of normal physiological findings. Glucagon receptor gene (GCGR) sequencing revealed a heterozygous deletion, K349_G359del and 4 missense mutations. This case may potentially represent a progenitor stage of glucagon cell adenomatosis with hyperglucagonemia in the absence of glucagonoma syndrome. The identification of novel GCGR mutations suggests that these may represent the underlying cause of this condition.

Pneumocystis pneumonia complicating immunosuppressive therapy in Crohns disease: A preventable problem?

We report the case of a 76-year-old man who presented with moderate active Crohns colitis that was refractory to high-dose corticosteroids, mesalazine and 6-mercaptopurine. He subsequently received a trial of infliximab with poor response and was diagnosed with cytomegalovirus (CMV) colitis, improving on antiviral therapy. Three weeks into treatment he developed acute respiratory distress with hypoxaemia and diffuse pulmonary interstitial infiltrates. This was confirmed as Pneumocystis jirovecii on bronchoalveolar lavage. He responded well to treatment with trimethoprim-sulfamethoxazole (TMP-SMX) and was subsequently discharged home. Despite the favourable outcome, our case raises the question of whether chemoprophylaxis against opportunistic infections in immunosuppressed patients with inflammatory bowel disease (IBD) is appropriate. There are currently no recommendations on providing chemoprophylaxis against CMV colitis and so we focus on pneumocystis pneumonia (PCP) where wide debate surrounds the use of prophylactic TMP-SMX in HIV-negative patients. Contrasting approaches to chemoprophylaxis against PCP in IBD likely relates to a lack of clear parameters for defining risk of PCP among patient groups. This must be addressed in order to develop universal guidelines that take into account patient-dependent risk factors. Awareness of the severity of PCP among HIV-negative individuals and the current consensus on PCP prophylaxis in IBD must be raised in order to minimise the risk of PCP and drive research in this controversial area.

Reactive Lymphoid Hyperplasia of the Pancreas: A Clinical Conundrum

CONTEXT Localized reactive lymphoid hyperplasia is a rare condition characterized by the presence of lymphoid follicles. CASE REPORT We describe a case of a 60-year-old woman who presented with right upper quadrant pain and was found to have a reactive nodular hyperplasia of the pancreas involving the uncinate process, body and tail of the gland. Due to the multifocal distribution of these hypoechoic vascular lesions, a total pancreatectomy was performed since malignancy could not be safely excluded. CONCLUSION There have been a handful of cases reporting reactive lymphoid hyperplasia affecting the pancreas; however, it is uncommon to perform such a radical pancreatic resection for this benign condition.

Duplication cyst of the appendix: a proposal for modification of the Cave-Wallbridge classification.

gations of choice with DUS useful at determining lower limb and iliac vein patency. Positron emission tomography imaging is essential to ruling out metastasis and differentiating curative from palliative surgical candidates. Surgical resection follows traditional oncologic resection principles and the approach is guided by the relationship of the tumour to the renal and hepatic veins. En‐bloc resection with clear margins and consideration of venous reconstruction allows the best chance at cure while minimizing postoperative morbidity. When dealing with the suprarenal segment, the need for nephrectomy and chronic lower limb oedema can be minimized with reconstruction using either prosthetic graft, superficial femoral vein or homograft. Prognosis is considered poor and reflects that of retroperitoneal sarcoma. Following radical resection, a mean survival of 36 months is expected with a 5‐ and 10‐year survival of 49.4% and 29.5% respectively. It is postulated that improved survival of middle IVC segment tumours reflects the relative proximity of surrounding organs and subsequent earlier development of symptoms. The benefit of either chemotherapy or radiotherapy has not been conclusively demonstrated leaving complete surgical resection with clear margins the gold standard of treatment. References

PTH-003 Clinical assessment is superior to pathological assessment in determining completeness of excision of malignant polyps from the Bowel Cancer Screening Programme

Introduction The management of the early malignant colorectal polyp is controversial. Currently estimates of lymph node involvement rely on pathological staging. Despite the risk of surgical intervention, there is an increasing trend to treat these tumours aggressively. The introduction of the Bowel Cancer Screening Programme (BCSP) in 2006 has increased the incidence of early colorectal polyp cancers, making management of these lesions a common clinical problem. Methods All malignant polyps reported to be completely excised endoscopically within the BCSP between the period 1 October 2007 to 31 October 2009 were identified. All were discussed in the local MDT and the decision to proceed to surgical resection was based on many factors, including pathological complete resection, Haggitt/Kikuchi level, as well as other high-risk features such as lymphovascular invasion and tumour budding. Those for which surgery was suggested were included in the study. The pathological assessment of completeness of excision was recorded, as well as the degree of differentiation of the tumour. Following surgery the presence of residual tumour within the resection specimen was recorded, as well as the total number of retrieved lymph nodes and the presence of lymph node tumour infiltration. Results 14 malignant polyps were felt to have been completely endoscopically resected during 726 colonoscopies within the study dates. Nine were pedunculated (64%) and five sessile (36%). There were no endoscopic complications. Six polyps (43%) were assessed to be incompletely excised after pathological review, one was pedunculated (17%) and five sessile (83%). 11 cancers (79%) were moderately differentiated and three (21%) were poorly differentiated. No post-surgical specimens had residual tumour present and there were no involved lymph nodes (mean number harvested 18, range, 1–62). One patient had a post operative anastomotic leak but there were no post operative deaths. All the lesions removed were Dukes A stage and there has been no tumour recurrence to date, over a mean follow-up of 9.5 months. Conclusion Although the follow-up is short, these data suggest that endoscopic resection may be a curative treatment for malignant polyps, thus avoiding subsequent surgery and possible complications. Endoscopic, rather than pathological, assessment of complete resection may be a more reliable predictor of residual tumour, particularly in sessile lesions. The surgical rates for these large flat lesions could potentially be reduced by greater uptake of Endoscopic Submucosal Dissection, but careful technique and visualisation following standard polypectomy may avoid this lengthy and high-risk endoscopic intervention.