Proteomic analysis of pancreatic intraepithelial neoplasia and pancreatic carcinoma in rat models

AIM:To detect the proteomic variabilities of pancreatic intraepithelial neoplasia(PanIN)and pancreatic carcinoma(PC)induced by 7,12-dimethylbenzanthracene(DMBA) in rat models and to identify potential biomarkers.METHODS:Sixty adult male Sprague Dawley rats were randomized into three groups.The rats had DMBA implanted into their pancreas for one(n=20)or two months(n=20)or assigned to the normal group(n =20).The rats were killed after one or two months,and were evaluated histopathologically.Three tissue samples from each group of rats with either normal pancreas,PanIN(PanIN-2)or PC were examined by 2D-DIGE.The different expression spot features were analyzed by matrix-assisted laser desorption/ionizationtime of flight/time of flight(MALDI-TOF/TOF)tandem mass spectrometry.The expression of enolase 1,a differentially expressed protein,was identified by immu-nohistochemistry.RESULTS:There was significant difference in the proportions of neoplastic changes between the 1-and 2-mogroups(P=0.0488).There was an increase in the frequency of adenocarcinomas in the 2-mo group compared with the 1-mo group(P=0.0309).No neoplastic changes were observed in any of the animals in the normal group.Enolase 1,pancreatic ELA3B,necdin,Hbp23,CHD3,hnRNP A2/B1,Rap80,and Gnb2l1 were up-regulated in the PanIN and PC tissues,and CEL,TPT1,NME2,PCK2,an unnamed protein product,and glycine C-acetyltransferase were down-regulated in the PanIN and PC tissues.The immunohistochemical results showed that enolase 1 expression was up-regulated in the pancreatic cancer tissues of rats and humans.CONCLUSION:The pancreatic protein expression changes induced by DMBA suggest potential molecular targets for the early diagnosis and treatment of PC.

Pancreatic intraepithelial neoplasia arising from an ectopic pancreas in the small bowel

BACKGROUND： Ectopic pancreatic tissue is relatively uncommon, and is characterized as pancreatic tissue with no contact with the normal pancreas, and with its own ductal system and blood supply. It is usually asymptomatic, and can be incidentally diagnosed by conventional imaging studies. METHOD： A 69-year-old woman with a prior history of bilateral breast carcinoma presented with ectopic pancreatic intraepithelial neoplasia （PanIN） that was identified incidentally in the small bowel during an oncological resection of a synchronous primary pancreatic adenocarcinoma, and renal cell carcinoma. RESULTS： The patient underwent subtotal pancreatectomy with splenectomy, regional lymphadenectomy, radical left nephrectomy, and small bowel resection with primary anastomosis of ectopic PanlN-2. She had an uneventful hospitalization and was discharged home on postoperative day 7. CONCLUSIONS： The occurrence of ectopic PanIN is extremely unusual with only few cases previously reported in the literature. The need for negative margins after surgical resection of ectopic PanIN lesions remains controversial.

Mutations in the p16 gene in DMBA-induced pancreatic intraepithelial neoplasia and pancreatic cancer in rats

BACKGROUND：7,12-dimethylbenzanthracene（DMBA）-induced pancreatic intraepithelial neoplasia（PanIN）and pancreatic cancer in rats provide a classic model for uncovering the molecular mechanisms underlying pancreatic cancer.However,this model has not been characterized genetically,and in particular,the major genetic alterations in the p16 gene are unknown.METHODS： Lesions of PanlN and pancreatic cancer were induced with DMBA implantation in 40 rats, and control pancreatic tissue was obtained from 10 age-matched rats without exposure to DMBA. Pancreatic tissue was harvested three months after DMBA implantation and DNA was extracted. Homozy- gous deletions and point mutations of the pl6 （exons 1 and 2） gene were detected by PCR amplification and direct sequencing. RESULTS： DMBA implantation in the 40 rats induced 26 Pan- INs and 9 carcinomas. The overall frequency of p 16 alterations in the pancreatic tissue of these rats was 42.86% （15/35）, and the changes were point mutations, not homozygous deletions. p16 mutations were present in 30.77% （8/26） of the rats with PanIN and 77.78% （7/9） of the rats with carcinoma （P〈0.05）. The increasing incidence of p16 alterations was detected in 20.00% （1/5） of PanIN-1, 28.57% （2/7） of PanIN-2 and 35.71% （5/14） of PanIN-3 lesions. CONCLUSION： Our findings indicated that p16 alteration is a common event in the carcinogenesis of this model and that the mutation pattern is analogous to that of human lesions.

E-cadherin and β-catenin expression in pancreatic intraepithelial neoplasia and pancreatic adenocarcinoma

Objective: To investigate the significance of abnormal E-cadherin and β-catenin expression in pancreatic intraepithelial neoplasia (PanIN) and pancreatic adenocarcinoma. Methods:Pancreatic samples of 156 cases were retrospectively studied from surgery and autopsy in Changhai hospital from January 2001 to December 2003, from which tissue microarray blocks containing 129 PanIN-1A lesions, 104 PanIN-1B lesions, 22 PanIN-2 lesions, 11 PanIN-3 lesions, and 121 pancreatic ductal adenocarcinomas and corresponding paracancerous tissues were constructed. EnVision method of immunohistochemistry was used to detect the E-cadherin and β-catenin expression. The correlation between the abnormal E-cadherin and β-catenin expression and clinicopathological parameters was analysed. Results: The rate of E-cadherin abnormal expression was significant in ductal adenocarcinomas compared with the PanIN lesions and normal ducts(64.5%,32.3%,0%), moreover, the rate of E-cadherin abnormal expression was in relation to differentiation, lymph node metastasis and perineural invasion of pancreatic adenocarcinoma(P<0.05). There was remarkable increase in the E-cadherin cytoplasmic expression in PanIN lesions and ductal adenocarcinomas compared with normal ducts. The rate of β-catenin abnormal expression was found to be related with lymph node metastasis and perineural invasion of pancreatic adenocarcinoma(P<0.05). The expression of β-catenin cytoplasm and/or nucleus was significant in high-grade PanIN lesions and ductal adenocarcinomas compared with low grade PanIN lesions or normal ducts(P<0.05). There was a positive relationship between the E-cadherin and β-catenin expression in PanIN lesions and ductal adenocarcinomas (P<0.01, P<0.05). Conclusion: There is aberration in the expression of the E-cadherin and β-catenin in PanIN lesions and ductal adenocarcinomas, suggesting the E-cadherin and β-catenin changes is not only related with the biological action and prognosis, but also involved in pancreatic carcinogenesis.

High-grade pancreatic intraepithelial lesions： prevalence and implications in pancreatic neoplasia

BACKGROUND： High-grade pancreatic intraepithelial neoplasia（Pan IN-3）, a precursor of pancreatic ductal adenocarcinoma（PDAC）, is not universally detected in resected pancreatic neoplasms. We sought to determine the prevalence and prognostic relevance of Pan IN-3 lesions in primary surgical resections of PDACs and intraductal papillary mucinous neoplasms（IPMNs）.METHODS： A retrospective review of a tertiary care center pathology database（1/2000-6/2014） was performed. Demographics, imaging, pathology, disease-recurrence, and survival data were reviewed.RESULTS： A total of 458 patients who underwent primary pancreatic resection were included. “Pan IN-3” lesions were found in 74（16.2%） patients who either had PDAC（n=67） or main duct（MD）-IPMN（n=7）. Among IPMN-MDs, Pan IN-3 lesions were exclusively found in those with pathological evidence of chronic pancreatitis. For PDACs, the median overall survival（OS） for pancreata with Pan IN-3 lesions was significantly better than those without（OS 1.12 years, interquartile range [IQR] 0.72, 2.05 years vs OS 0.86 years, IQR 0.64,1.60 years respectively; P=0.04）. Multivariate Cox regression analysis demonstrated that the presence of Pan IN-3 lesions was associated with a reduced risk of death（HR=0.43; 95% CI： 0.23-0.82; P=0.01）.CONCLUSIONS： Following primary resection of pancreatic adenocarcinoma, the lower survival observed in patients without Pan IN-3 lesions might suggest a state of complete or accelerated transformation. Further investigations are necessary to validate these findings that might impact disease prognosis and management.

Pancreatic ductal adenocarcinoma associated with pancreatic ductal intraepithelial neoplasia(The Author reply)

The Editor welcomes submissions for possible publication in the Letters to the Editor section that consist of commentary on an article published in the Journal or other relevant issues.

Pancreatic ductal adenocarcinoma associated with pancreatic ductal intraepithelial neoplasia

To the Editor:I read the report of Krishnasamy et al1 with great interest.The authors make a valid point about management issues associated with pancreatic ductal intraepithelial neoplasia (PanIN) in their illustrativereport.However,a few clarifications need to be made on surgical pathology aspect of these lesions. Without

Nuclear receptors and pathogenesis of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a median overall survival time of 5 mo and the five years survival less than 5%, a rate essentially unchanged over the course of the years. A well defined progression model of accumulation of genetic alterations ranging from single point mutations to gross chromosomal abnormalities has been introduced to describe the origin of this disease. However, due to the its subtle nature and concurring events PDAC cure remains elusive. Nuclear receptors (NR) are members of a large superfamily of evolutionarily conserved ligand-regulated DNA-binding transcription factors functionally involved in important cellular functions ranging from regulation of metabolism, to growth and development. Given the nature of their ligands, NR are very tempting drug targets and their pharmacological modulation has been widely exploited for the treatment of metabolic and inflammatory diseases. There are now clear evidences that both classical ligand-activated and orphan NR are involved in the pathogenesis of PDAC from its very early stages; nonetheless many aspects of their role are not fully understood. The purpose of this review is to highlight the striking connections that link peroxisome proliferator activated receptors, retinoic acid receptors, retinoid X receptor, androgen receptor, estrogen receptors and the orphan NR Nur, chicken ovalbumin upstream promoter transcription factor II and the liver receptor homologue-1 receptor to PDAC development, connections that could lead to the identification of novel therapies for this disease.

Overexpression of catechol-O-methyltransferase occurs early in the progression of pancreatic cancer

Aims:Catechol-O-methyltransferase(COMT)plays a role in many kinds of cancer,and its high expression in pancreatic cancer has been found to be related to better prognosis.However,the expression and biological significance of COMT in multistep pancreatic cancerogenesis is not clear.Main methods:Six LSL-Kras^(G12D)-positive and Pdx1-Cre-positive mice(Kras^(G12D)mice),6 wild-type mice and 1 human tissue microarray were used in this study.COMT protein expression was measured by immunohistochemistry,and DNA chips were made for use in COMT mRNA assays.Keyfindings:The expression of COMT in pancreatic intraepithelial neoplasias(PanINs)from Kras^(G12D)mice was significantly higher than that in normal pancreatic tissue from wild-type mice,both in terms of protein level and mRNA expression.The median COMT immunohistochemistry expression scores in human PanIN-1 and PanIN-2 were 70 and 160,respectively,which were significantly lower than the score of 170 observed in pancreatic ductal adenocarcinoma(PDAC)(P=.024 and.037,respectively)and significantly higher than the score of 25 observed in pancreatitis(P=.01 and.008,respectively).Significance:In the development of pancreatic cancer from chronic pancreatitis and in the transition of PanIN to PDAC,we observed significantly increased expression of COMT.These data predict that the overexpression of COMT is an early event in the multistep process of pancreatic cancerogenesis.