Premalignant conditions of the pancreas

The ubiquitin ligase RNF43 downregulation increases membrane expression of frizzled receptor in pancreatic ductal adenocarcinoma

RNF43 is a novel tumor suppressor protein and known to be expressed in a multitude of tissue and dysregulated in cancers of these organs including ovarian and colorectal tissues. RNF43 expression has been shown to be expressed in mutated forms in several pancreatic cell lines. RNF43, by virtue of being an ubiquitin ligase, has the potential to ubiquitinylate membrane receptors like frizzled that subserves sensing Wnt soluble signals at the cell membrane. Thus, normally, RNF43 downregulates Wnt signaling by removing frizzled receptor from the membrane. In the present study, the expression of the tumor suppressor RNF43 was examined in human patient samples of pancreatic ductal adenocarcinoma (PDAC). Reduced levels of expression of RNF43 in PDAC were demonstrated by Western blotting. We incorporated membrane biotinylation assay to examine the expression of frizzled6 receptor in the membrane and demonstrated that it is significantly increased in PDAC tissues. This may be responsible for enhanced Wnt/beta-catenin signaling and provides the first level of evidence of a possible role of this well-known pathway in pancreatic exocrine carcinogenesis. We have utilized appropriate controls to ensure the true positivity of the findings of the present study. The contribution of Wnt/beta-catenin/RNF43 pathway in pancreatic carcinogenesis may provide for utilization of pharmacologic resources for precision-based approaches to treat pancreatic ductal adenocarcinoma.

Endoscopic ultrasonography for surveillance of individuals at high risk for pancreatic cancer

Pancreatic cancer is a highly lethal disease with a genetic susceptibility and familial aggregation found in 3%-16% of patients. Early diagnosis remains the only hope for curative treatment and improvement of prognosis. This can be reached by the implementation of an intensive screening program, actually recommended for individuals at high-risk for pancreatic cancer development. The aim of this strategy is to identify pre-malignant precursors or asymptomatic pancreatic cancer lesions, curable by surgery. Endoscopic ultrasound (EUS) with or without fine needle aspiration (FNA) seems to be the most promising technique for early detection of pancreatic cancer. It has been described as a highly sensitive and accurate tool, especially for small and cystic lesions. Pancreatic intraepithelial neoplasia, a precursor lesion which is highly represented in high-risk individuals, seems to have characteristics chronic pancreatitis-like changes well detected by EUS. Many screening protocols have demonstrated high diagnostic yields for pancreatic pre-malignant lesions, allowing prophylactic pancreatectomies. However, it shows a high interobserver variety even among experienced endosonographers and a low sensitivity in case of chronic pancreatitis. Some new techniques such as contrast-enhanced harmonic EUS, computer-aided diagnostic techniques, confocal laser endomicroscopy miniprobe and the detection of DNA abnormalities or protein markers by FNA, promise improvement of the diagnostic yield of EUS. As the resolution of imaging improves and as our knowledge of precursor lesions grows, we believe that EUS could become the most suitable method to detect curable pancreatic neoplasms in correctly identified asymptomatic at-risk patients.

Evaluation of magnifying colonoscopy in the diagnosis of serrated polyps

AIM

To elucidate the colonoscopic features of serrated lesions of the colorectum using magnifying colonoscopy.

METHODS

Broad division of serrated lesions of the colorectum into hyperplastic polyps (HPs), traditional serrated adenomas (TSAs), and sessile serrated adenomas/polyps (SSA/Ps) has been proposed on the basis of recent molecular biological studies. However, few reports have examined the colonoscopic features of these divisions, including magnified colonoscopic findings. This study examined 118 lesions excised in our hospital as suspected serrated lesions after magnified observation between January 2008 and September 2011. Patient characteristics (sex, age), conventional colonoscopic findings (location, size, morphology, color, mucin) and magnified colonoscopic findings (pit pattern diagnosis) were interpreted by five colonoscopists with experience in over 1000 colonoscopies, and were compared with histopathological diagnoses. The pit patterns were categorized according to Kudo's classification, but a more detailed investigation was also performed using the subclassification [type II-Open (type II-O), type II-Long (type II-L), or type IV-Serrated (type IV-S)] proposed by Kimura T and Yamano H.

RESULTS

Lesions comprised 23 HPs (23/118: 19.5%), 39 TSAs (39/118: 33.1%: with cancer in one case), 50 SSA/Ps (50/118: 42.4%: complicated with cancer in three cases), and six others (6/118: 5.1%). We excluded six others, including three regular adenomas, one hamartoma, one inflammatory polyp, and one juvenile polyp for further analysis. Conventional colonoscopy showed that SSA/Ps were characterized as larger in diameter than TSAs and HPs (SSA/P vs HP, 13.62 ± 8.62 mm vs 7.74 ± 3.24 mm, P < 0.001; SSA/Ps vs TSA, 13.62 ± 8.62 mm vs 9.89 ± 5.73 mm, P < 0.01); common in the right side of the colon [HPs, 30.4% (7/23): TSAs, 20.5% (8/39): SSA/P, 84.0% (42/50), P < 0.001]; flat-elevated lesion [HPs, 30.4% (7/23): TSAs, 5.1% (2/39): SSA/Ps, 90.0% (45/50), P < 0.001]; normal-colored or pale imucosa [HPs, 34.8% (8/23): TSAs, 10.3% (4/39): SSA/Ps, 80% (40/50), P < 0.001]; and with large amounts of mucin [HPs, 21.7% (5/23): TSAs, 17.9% (7/39): SSA/Ps, 72.0% (36/50), P < 0.001]. In magnified colonoscopic findings, 17 lesions showed either type II pit pattern alone or partial type II pit pattern as the basic architecture, with 14 HPs (14/17, 70.0%) and 3 SSA/Ps. Magnified colonoscopy showed the type II-O pit pattern as characteristic of SSA/Ps [sensitivity 83.7% (41/49), specificity 85.7% (54/63)]. Cancer was also present in three lesions, in all of which a type VI pit pattern was also present within the same lesion. There were four HPs and four TSAs each. The type IV-S pit pattern was characteristic of TSAs [sensitivity 96.7% (30/31), specificity 89.9% (72/81)]. Cancer was present in one lesion, in which a type VI pit pattern was also present within the same lesion. In our study, serrated lesions of the colorectum also possessed the features described in previous reports of conventional colonoscopic findings. The pit pattern diagnosis using magnifying colonoscopy, particularly magnified colonoscopic findings using subclassifications of surface architecture, reflected the pathological characteristics of SSA/Ps and TSAs, and will be useful for colonoscopic diagnosis.

CONCLUSION

We suggest that this system could be a good diagnostic tool for SSA/Ps using magnifying colonoscopy.

Individuals at high-risk for pancreatic cancer development: management options and the role of surgery

Pancreatic cancer (PC) is a highly lethal disease. Despite advances regarding the safety and long-term results of pancreatectomies, early diagnosis remains the only hope for cure. This necessitates the implementation of an intensive screening program (based mainly on modern imaging), which - given the incidence of PC - is not cost effective for the general population. However, this screening program is recommended for individuals at high-risk for PC development. Indications for screening include the following three clinical settings: hereditary cancer predisposition syndromes associated with PC, hereditary pancreatitis and familial pancreatic cancer syndrome. The aim of this strategy is to identify pre-invasive (precursor) lesions, which are curable. Surgery is recommended in the presence of recognizable lesion on imaging lesions. Partial (anatomic) pancreatectomy - depending on the location of the suspicious lesion - is the most widely accepted type of surgical intervention in this setting; occasionally, however, total pancreatectomy may be required, in carefully selected patients. Despite that experience still remains limited, there is evidence that this aggressive strategy allows early detection of neoplastic lesions, thereby improving the effectiveness of surgery and prognosis.

The role of tobacco-derived carcinogens in pancreas cancer

The extremely poor outcome from pancreas cancer is well known. However, its aetiology less well appreciated, and the molecular mechanisms underlying this are poorly understood. Tobacco usage is one of the strongest risk factors for this disease, and this is a completely avoidable hazard. In addition, there are well described hereditary diseases which predispose, and familial pancreas cancer. We have sought here to summarise the role of tobacco-derived carcinogens and the mode of their tumorigenic action on the pancreas. There is compelling evidence from animal and human studies (laboratory including cell line studies and epidemiologic) that tobacco derived carcinogens cause pancreas cancer. However, the manner in which they do so is not entirely apparent. There is also compelling evidence that synergism with genetic and other life-style factors-like diet obesity-results in a multifactorial causation of the disease. Ascertaining the role of tobacco carcinogens in the development of this cancer and their interaction with other risk factors will enable novel therapeutic and preventative strategies to improve outcome from this appalling malignancy.

Preemptive surgery for premalignant foregut lesions

INTRODUCTION

Preemptive surgery is the prophylactic removal of an organ at high risk for malignant transformation or the resection of a precancerous or "early" malignant neoplasm in an individual with a hereditary predisposition to cancer. Recent advances in molecular diagnostic techniques have improved our understanding of the biologic behavior of these conditions. Predictive testing is an emerging field that attempts to assess the potential risk of cancer development in predisposed individuals. Despite substantial improvement in these forms of testing, all results are imperfect. This information often becomes an important tool that is used by healthcare providers to evaluate the risk-benefit ratio of various risk modifying strategies (i.e., intensive surveillance or preemptive surgery).

METHODS

A systematic literature review was performed using Medline and the bibliographies of all referenced publications to identify articles relating to preemptive surgery for premalignant foregut lesions.

RESULTS AND DISCUSSION

In this review, we outline the controversies surrounding predictive risk assessment, surveillance strategies, and preemptive surgery in the management of high-grade dysplasia (HGD) in Barrett's esophagus (BE), hereditary diffuse gastric cancer (HDGC), bile duct cysts, primary sclerosing cholangitis (PSC), and pancreatic cystic neoplasms. Resection of BE is supported by the progressive nature of the disease, the risk of occult carcinoma, and the lethality of esophageal cancer. Prophylactic total gastrectomy for HDGC appears reasonable in the absence of accurate screening tests but must be balanced by the impact of surgical complications and altered quality of life. Surgical resection of biliary cysts theoretically eliminates the exposed epithelium to decrease the lifetime risk of cholangiocarcinoma. Liver transplantation for PSC remains controversial given the scarcity of donor organs and inability to accurately identify high-risk individuals. Given the uncertain natural history of pancreatic cystic neoplasms, the merits of selective versus obligatory resection will continue to be debated.

CONCLUSIONS

Preemptive operations require optimal judgment and surgical precision to maximize function and enhance survival. Ultimately, balancing the risk of surgical intervention with less invasive interventions or observation must be individualized on a case-by-case basis.

Artificial neural networks in pancreatic disease

BACKGROUND

An artificial neural network (ANNs) is a non-linear pattern recognition technique that is rapidly gaining in popularity in medical decision-making. This study investigated the use of ANNs for diagnostic and prognostic purposes in pancreatic disease, especially acute pancreatitis and pancreatic cancer.

METHODS

PubMed was searched for articles on the use of ANNs in pancreatic diseases using the MeSH terms 'neural networks (computer)', 'pancreatic neoplasms', 'pancreatitis' and 'pancreatic diseases'. A systematic review of the articles was performed.

RESULTS

Eleven articles were identified, published between 1993 and 2007. The situations that lend themselves best to analysis by ANNs are complex multifactorial relationships, medical decisions when a second opinion is needed and when automated interpretation is required, for example in a situation of an inadequate number of experts.

CONCLUSION

Conventional linear models have limitations in terms of diagnosis and prediction of outcome in acute pancreatitis and pancreatic cancer. Management of these disorders can be improved by applying ANNs to existing clinical parameters and newly established gene expression profiles.

A family history of pancreatic cancer

BACKGROUND

A 65-year-old white male with a family history of pancreatic cancer and a personal history of two episodes of acute pancreatitis was referred to our department in January 2005 by his primary-care physician for an assessment of his pancreatic cancer risk.

INVESTIGATIONS

Physical exam, laboratory investigations, CT scan, endoscopic ultrasonography, endoscopic retrograde cholangiopancreatography.

DIAGNOSIS

Familial pancreatic cancer.

MANAGEMENT

Subtotal pancreatectomy, referral to genetic counselor, and continued surveillance.

Difficulty with diagnosis of malignant pancreatic neoplasms coexisting with chronic pancreatitis

Chronic pancreatitis is a relatively common disease. We encountered two different cases of belatedly demonstrated pancreatic carcinoma featuring underlying chronic pancreatitis. The first case was one that was highly suspected as that of a malignancy based upon imaging study, but unfortunately, it could not be confirmed by intra-operative cytology at that time. Following this, the surgeon elected to perform only conservative bypass surgery for obstructive biliary complication. Peritoneal carcinomatosis was later noted and the patient finally died. The second case, a malignant mucinous neoplasm, was falsely diagnosed as a pseudocyst, based upon the lesion’s sonographic appearance and associated elevated serum amylase levels. After suffering repeated hemoptysis, the patient was found to exhibit lung metastasis and peritoneal seeding. We reviewed some of the literature, including those studies discussing chronic pancreatitis predisposing to a malignant change. These two case analyses illustrate clearly that the diagnosis for such conditions, which is simply based upon imagery or pathological considerations may end up being one of a mistaken malignancy. Some of our suggestions for the treatment of such malignancies as revealed herein include, total pancreatomy for univocal mass lesion, and needle aspiration of lesion-contained tissue for amylase, CA199 and CEA levels for a suspicious cystic pancreatic mass.

Expression of inducible nitric oxide synthase and cyclooxygenase-2 in pancreatic adenocarcinoma: Correlation with microvessel density

AIM: Cyclooxygenases (COX) are key enzymes for conversion of arachidonic acid to prostaglandins. Nitric oxide synthase (NOS) is the enzyme responsible for formation of nitric oxide. Both have constitutive and inducible isoforms. The inducible isoforms (iNOS and COX-2) are of great interest as regulators of tumor angiogenesis, tumorigenesis and inflammatory processes. This study was to clarify their role in pancreatic adenocarcinomas.

METHODS: We investigated the immunohistochemical iNOS and COX-2 expression in 40 pancreatic ductal adenocarcinomas of different grade and stage. The results were compared with microvessel density and clinicopathological data.

RESULTS: Twenty-one (52.5%) of the cases showed iNOS expression, 15 (37.5%) of the cases were positive for COX-2. The immunoreaction was heterogeneously distributed within the tumors. Staining intensity was different between the tumors. No correlation between iNOS and COX-2 expression was seen. There was no relationship with microvessel density. However, iNOS positive tumors developed more often distant metastases and the more malignant tumors showed a higher COX-2 expression. There was no correlation with other clinicopathological data.

CONCLUSION: Approximately half of the cases expressed iNOS and COX-2. These two enzymes do not seem to be the key step in angiogenesis or carcinogenesis of pancreatic adenocarcinomas. Due to a low prevalence of COX-2 expression, chemoprevention of pancreatic carcinomas by COX-2 inhibitors can only achieve a limited success.

Expression of cancer testis antigens in pancreatic carcinoma cell lines, pancreatic adenocarcinoma and chronic pancreatitis

In order to define antigens that might be suitable as vaccines for pancreatic carcinoma, we investigated the composite expression of 10 cancer testis (CT) antigens (SCP-1, NY-ESO-1, SSX-1, SSX-2, SSX-4, GAGE, MAGE-3, MAGE-4, CT-7 and CT-8) by Reverse Transcriptase-PCR (RT-PCR) in fresh biopsies of human pancreatic adenocarcinoma, chronic pancreatitis and pancreatic carcinoma cell lines. While all CT genes were frequently expressed in cell lines derived from pancreatic cancer, no expression of MAGE-3, SSX-1, SSX-2, NY-ESO-1 and CT-7 was detected in fresh tumor biopsies, and MAGE-4 (1/52), SSX-4 (1/39) and CT-8 (2/41) were only rarely expressed. In contrast, HOM-TES-14/SCP-1 was expressed in 48% (29/61) and GAGE in 21% (13/61) of cases, respectively. One CT gene was expressed by 59% (75% in male, 46% in female patients; p = 0.05) and 2 or more CT genes by 15% of the samples. SCP-1 protein expression correlated well with mRNA expression. While SCP-1 and GAGE were absent in normal pancreas, they were found in 2/8 (SCP-1) and 1/8 (GAGE) samples of chronic pancreatitis, respectively, supporting the concept of chronic pancreatitis as a premalignant condition. SCP-1 and GAGE represent promising candidates for vaccine development in pancreatic carcinoma. Whether SCP-1 and GAGE expression identify cases of chronic pancreatitis with a high risk of malignant transformation remains to be shown.