Expression of Wnt-signaling pathway proteins in intraductal papillary mucinous neoplasms of the pancreas: a tissue microarray analysis

PGC1α-Mediated Metabolic Reprogramming Drives the Stemness of Pancreatic Precursor Lesions

PURPOSE

Metabolic reprogramming and cancer stem cells drive the aggressiveness of pancreatic ductal adenocarcinoma (PDAC). However, the metabolic and stemness programs of pancreatic precursor lesions (PPL), considered early PDAC development events, have not been thoroughly explored.

EXPERIMENTAL DESIGN

Meta-analyses using gene expression profile data from NCBI Gene Expression Omnibus and IHC on tissue microarrays (TMA) were performed. The following animal and cellular models were used: cerulean-induced Kras^G12D; Pdx1 Cre (KC) acinar-to-ductal metaplasia (ADM) mice, Kras^G12D; Smad4^Loss; Pdx-1 Cre (KC^Smad4-) intraductal papillary mucinous neoplasm (IPMN) mice, LGKC1 cell line derived from the doxycycline-inducible Gnas IPMN model, and human IPMN organoids. Flow cytometry, Seahorse extracellular flux analyzer, qRT-PCR, and sphere assay were used to analyze metabolic and stemness features. SR18292 was used to inhibit PGC1α, and short hairpin RNA was used to knockdown (KD) PGC1α.

RESULTS

The meta-analysis revealed a significant upregulation of specific stemness genes in ADM-mediated pancreatic intraepithelial neoplasms (PanIN) and IPMN. Meta- and TMA analyses followed by in vitro and in vivo validation revealed that ADM/PanIN exhibit increased PGC1α and oxidative phosphorylation (OXPhos) but reduced CPT1A. IPMN showed elevated PGC1α, fatty acid β-oxidation (FAO) gene expression, and FAO-OXPhos. PGC1α was co-overexpressed with its coactivator NRF1 in ADM/PanINs and with PPARγ in IPMN. PGC1α KD or SR18292 inhibited the specific metabolic and stemness features of PPLs and repressed IPMN organoid growth.

CONCLUSIONS

ADM/PanINs and IPMNs show specific stemness signatures with unique metabolisms. Inhibition of PGC1α using SR18292 diminishes the specific stemness by targeting FAO-independent and FAO-dependent OXPhos of ADM/PanINs and IPMNs, respectively.

Benign Adrenocortical Tumors and the Detection of Nonadrenal Neoplasia

CONTEXT

Patients with adrenocortical tumors have been frequently observed to have nonadrenal neoplasia.

OBJECTIVE

To investigate whether patients with benign adrenocortical tumors have a higher likelihood of having nonadrenal neoplasia detected.

DESIGN AND PARTICIPANTS

Case-control study of patients with benign adrenocortical tumors (cases; n = 400) and normal adrenal glands (controls; n = 400), who underwent repeated abdominal cross-sectional imaging.

MAIN OUTCOMES

Primary analyses: association between case-control status and benign abdominal neoplasia detected via cross-sectional imaging. Secondary analyses: association between case-control status and tumors detected via other imaging modalities.

RESULTS

The mean interval of abdominal imaging was 4.7 (SD = 3.8) years for cases and 5.9 (4.8) years for controls. Cases were more likely to have detected intraductal papillary mucinous neoplasms (IPMNs) of the pancreas (8.5% vs. 4.5%, adjusted OR = 2.22, 95% CI (1.11, 4.63)) compared with controls. In secondary analyses, cases were more likely to have detected thyroid nodules (25.5% vs. 17.0%, adjusted OR = 1.77, 95% CI (1.15, 2.74)), hyperparathyroidism or parathyroid adenomas (3.5% vs. 1.3%, adjusted OR = 3.00, 95% CI (1.00, 11.64)), benign breast masses (6.0% vs. 3.3%, adjusted OR = 3.25, 95% CI (1.28, 8.78)), and benign prostatic hyperplasia (20.5% vs. 5.3%, adjusted OR = 3.20, 95% CI (1.14, 10.60)). Using a composite outcome, cases had higher odds of detection of the composite of IPMN, thyroid nodules, parathyroid tumors, benign breast masses, and prostate hyperplasia (adjusted OR = 2.36, 95% CI: 1.60, 3.50) when compared with controls.

CONCLUSIONS

Patients with benign adrenocortical tumors had higher odds of detected pancreatic IPMN, as well as thyroid nodules, parathyroid tumors, benign breast masses, and prostate hyperplasia compared with patients with normal adrenal glands. These associations may have important implications for patient care and healthcare economics, regardless of whether they reflect incidental discoveries due to imaging detection or frequency bias, or a common risk for developing multiple neoplasia.

New Developments in the Molecular Mechanisms of Pancreatic Tumorigenesis

Pancreatic cancer is an aggressive disease with a dismal prognosis in dire need of novel diagnostic and therapeutic approaches. The past decade has witnessed an explosion of data on the genetic alterations that occur in pancreatic cancer, as comprehensive next-generation sequencing analyses have been performed on samples from large cohorts of patients. These studies have defined the genomic landscape of this disease and identified novel candidates whose mutations contribute to pancreatic tumorigenesis. They have also clarified the genetic alterations that underlie multistep tumorigenesis in precursor lesions and provided insights into clonal evolution in pancreatic neoplasia. In addition to these important insights into pancreatic cancer biology, these large scale genomic studies have also provided a foundation for the development of novel early detection strategies and targeted therapies. In this review, we discuss the results of these comprehensive sequencing studies of pancreatic neoplasms, with a particular focus on how their results will impact the clinical care of patients with pancreatic cancer.

Notch Signaling in Pancreatic Development

The Notch signaling pathway plays a significant role in embryonic cell fate determination and adult tissue homeostasis. Various studies have demonstrated the deep involvement of Notch signaling in the development of the pancreas and the lateral inhibition of Notch signaling in pancreatic progenitor differentiation and maintenance. The targeted inactivation of the Notch pathway components promotes premature differentiation of the endocrine pancreas. However, there is still the contrary opinion that Notch signaling specifies the endocrine lineage. Here, we review the current knowledge of the Notch signaling pathway in pancreatic development and its crosstalk with the Wingless and INT-1 (Wnt) and fibroblast growth factor (FGF) pathways.

Cyst Features and Risk of Malignancy in Intraductal Papillary Mucinous Neoplasms of the Pancreas: Imaging and Pathology

Background

Intraductal papillary mucinous neoplasms (IPMNs) display diverse macroscopic, histological, and immunohistochemical characteristics with typical morphological appearance in magnetic resonance imaging. Depending on those, IPMNs may show progression into invasive carcinomas with variable frequency. Overall, IPMN-associated invasive carcinomas are found in about 30% of all IPMNs, revealing phenotpyes comparable with conventional ductal adenocarcinomas or mucinous (colloid) carcinomas of the pancreas. In Sendai-negative side-branch IPMNs, however, the annual risk of the development of invasive cancer is 2%; thus, risk stratification with regard to imaging and preoperative biomarkers and cytology is mandatory.

Methods and Results

The present study addresses the radiological and interventional preoperative measures including histological features to determine the risk of malignancy and the prognosis of IPMNs.

Conclusion

While preoperative imaging largely relies on the detection of macroscopic features of IPMNs, which are associated with a divergent risk of malignant behavior, in resected specimens the determination of the grade of dysplasia and the detection of an invasive component are the most important features to estimate the prognosis of IPMNs.

Hereditary Pancreatic Cancer Syndromes

Despite decades of scientific and clinical research, pancreatic ductal adenocarcinoma (PDAC) remains a lethal malignancy. The clinical and pathologic features of PDAC, specifically the known environmental and genetic risk factors, are reviewed here with special emphasis on the hereditary pancreatic cancer (HPC) syndromes. For these latter conditions, strategies are described for their identification, for primary and secondary prevention in unaffected carriers, and for disease management in affected carriers. Nascent steps have been made toward personalized medicine based on the rational use of screening, tumor subtyping, and targeted therapies; these have been guided by growing knowledge of HPC syndromes in PDAC.

Molecular biomarkers for progression of intraductal papillary mucinous neoplasm of the pancreas

OBJECTIVES

We aimed to identify molecular biomarkers for assessing the progression of intraductal papillary mucinous neoplasm of the pancreas (IPMN).

METHODS

We retrospectively investigated molecular aberrations and their associations with clinicopathological features in 172 IPMNs.

RESULTS

GNAS and KRAS mutations were detected in 48% and 56% of IPMNs, respectively. No mutations of EGFR, PIK3CA GNAO1, GNAQ, or GNAI2 were observed. Significant associations were observed between IPMN morphological types and GNAS mutations, KRAS mutations, the expression of phosphorylated MAPK (pMAPK), AKT, and phosphorylated AKT (pAKT), nuclear accumulation of β-catenin, SMAD4 loss, and TP53 overexpression; histological grades and the expression of EGFR, pMAPK, AKT, and pAKT, the nuclear β-catenin, SMAD4 loss, and TP53 overexpression; invasive phenotypes and KRAS mutations, the nuclear β-catenin, and SMAD4 loss; and prognosis and SMAD4 loss and TP53 overexpression. Multivariate analysis to compare prognostic impacts of multiple molecular features revealed that TP53 overexpression was an independent prognostic factor (P = 0.030; hazard ratio, 5.533).

CONCLUSIONS

These results indicate that mutations in GNAS and KRAS, the expression of EGFR and pMAPK, the nuclear β-catenin, SMAD4 loss, and TP53 overexpression may be relevant for assessing the clinical course of IPMN, including its progression into different morphological types, invasion, and prognosis.

Effect of Twist and Bmi1 on intraductal papillary mucinous neoplasm of the pancreas

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) is a well-established entity among pancreatic neoplasms that ranges from low-grade dysplasia to invasive carcinoma. Epithelial-mesenchymal transition (EMT) contributes to tumor progression in various cancers. Moreover, Notch signaling is one of the important upstream effectors of EMT promotion. Currently, it is unclear whether EMT causes pathological progression of IPMN.

AIM

We evaluated the expression of EMT-promoting transcription factors Twist and B cell-specific Moloney murine leukemia virus insertion site 1 (Bmi1) in IPMN.

METHODS

Patients who underwent resections at our institute and its affiliated hospital were enrolled in this study (n = 35). Protein expression of EMT markers Twist, Bmi1, Jagged1, and E-cadherin in resected specimens was investigated by immunohistochemistry. Expression of these proteins was compared with the clinicopathological factors and patient survival.

RESULTS

Positive expression of Twist and Bmi1 was observed in 40.0% and 42.9% of IPMNs, respectively. Twist and Bmi1 expression was significantly higher in IPMNs with high-grade dysplasia (P < 0.05) and invasive carcinoma (P < 0.05) than that in IPMNs with low-grade dysplasia. High expression of Twist was correlated with Jagged1 expression and inversely correlated with expression of E-cadherin (P = 0.06 and P < 0.05, respectively). In survival analyses, the recurrence rate was significantly higher in the group that showed simultaneous high expression of Twist and Bmi1 (P < 0.05).

CONCLUSIONS

Expression of Twist and Bmi1 is associated with aggressiveness and poor prognoses of IPMN through EMT promotion that might be induced by Notch signaling.

PP2A inhibitors suppress migration and growth of PANC-1 pancreatic cancer cells through inhibition on the Wnt/β-catenin pathway by phosphorylation and degradation of β-catenin

Cantharidin is an active constituent of mylabris, a traditional Chinese medicine, and presents strong anticancer activity in various cell lines. Cantharidin is a potent and selective inhibitor of serine/threonine protein phosphatase 2A (PP2A). Our previous studies revealed the prospect of application of cantharidin, as well as other PP2A inhibitors, in the treatment of pancreatic cancer. However, the mechanisms involved in the anticancer effect of PP2A inhibitors have not been fully explored. The Wnt/β-catenin pathway is involved in cell migration and proliferation and participates in the progression of pancreatic cancer. If β-catenin is phosphorylated and degraded, the Wnt/β-catenin pathway is blocked. PP2A dephosphorylates β-catenin and keeps the Wnt/β-catenin pathway active. In the present study, we found that PP2A inhibitor treatment induced phosphorylation and degradation of β-catenin. The suppression on the migration and growth of PANC-1 pancreatic cancer cells could be attenuated by pretreatment with FH535, a β-catenin pathway inhibitor. Microarray showed that PP2A inhibitor treatment induced expression changes in 13 of 138 genes downstream of the β-catenin pathway. Real-time PCR further confirmed that FH535 attenuated the expression changes induced by PP2A inhibitors in 6 of these 13 candidate genes. These 6 genes, VEGFB, Dkk3, KRT8, NRP1, Cacnalg and WISP2, have been confirmed to participate in the migration and/or growth regulation in previous studies. Thus, the phosphorylation- and degradation-mediated suppression on β-catenin participates in the cytotoxicity of PP2A inhibitors. Our findings may provide insight into the treatment of pancreatic cancer using a targeting PP2A strategy.

CD 99 immunocytochemistry in solid pseudopapillary tumor of pancreas: A study on fine-needle aspiration cytology smears

BACKGROUND

Solid pseudopapillary tumor of pancreas (SPTP) is a rare pancreatic tumor of uncertain histogenesis usually affecting young women. Though these tumors have characteristic cytomorphology, it is sometimes difficult to differentiate them from neuroendocrine tumors of the pancreas. We reviewed cases of SPTP to delineate the diagnostic cytological features and also observed utility of CD 99 (MIC 2) immunostaining to aid in the diagnosis of this tumor.

AIMS

This study was designed to demonstrate the utility of CD 99 immunostaining along with cytological features for making a pre-operative diagnosis and delineating it from the neuroendocrine tumor of pancreas which is a close mimic.

MATERIALS AND METHODS

Cytomorphological features of 11 cases of solid pseudopapillary neoplasm diagnosed by pre-operative fine-needle aspiration cytology (FNAC) at our institute were reviewed. Immunocytochemistry for CD 99 was also performed on the smears.

RESULTS

All the cases had cellular smears with monomorphic cells lying singly, as loosely cohesive clusters as well as forming delicate pseudopapillae. Presence of intra and extra-cellular basement membrane material, background foamy macrophages and nuclear grooves were the other salient features. Immunocytochemistry for CD 99 could be performed on eight cases and demonstrated typical paranuclear dot-like positivity.

CONCLUSIONS

Pre-operative early diagnosis of SPTP can be made by FNAC which can further be aided by CD 99 immunocytochemistry.

Synchronous pancreatic solid pseudopapillary neoplasm and intraductal papillary mucinous neoplasm

Solid pseudopapillary neoplasm (SPN) is a rare and low-grade malignant pancreatic neoplasm composed of poorly cohesive monomorphic neoplastic cells forming solid and pseudopapillary structures with frequent hemorrhagic-cystic degeneration. Intraductal papillary mucinous neoplasm (IPMN) is a pancreatic exocrine tumor composed of intraductal papillary growth of mucin containing neoplastic cells in the main pancreatic duct or its major branches. In the case presented here, a 53-year-old, Japanese man was found to have multiple cystic lesions and dilatation of the main pancreatic duct in the neck of the pancreas. Histological examination revealed a main-duct and branch-duct type IPMN, of the gastric-type, involving the neck of the pancreas, associated with a 0.5 cm SPN in the caudal side of the IPMN. We diagnosed this case as synchronous SPN and IPMN. As far as we know, only one other case of synchronous SPN and IPMN has been reported. Both the present case and the previously reported case showed abnormal nuclear expression of β-catenin in SPN, whereas IPMN showed no abnormal nuclear expression. These results suggest that β-catenin abnormality is not a common pathogenetic factor of synchronous SPN and IPMN.

Intraductal papillary mucinous neoplasm of the pancreas: an update

Intraductal papillary mucinous neoplasm (IPMN) is a cystic tumor of the pancreas. The etiology is unknown, but increasing evidence suggests the involvement of several tumorigenesis pathways, including an association with hereditary syndromes. IPMN occurs more commonly in men, with the mean age at diagnosis between 64 and 67 years old. At the time of diagnosis, it may be benign, with or without dysplasia, or frankly malignant with an invasive carcinoma. Tumors arising from the main pancreatic duct are termed main-duct IPMNs, those involving the branch ducts, branch-duct IPMNs. In general, small branch-duct IPMNs are benign, particularly in asymptomatic patients, and can be safely followed. In contrast, main-duct tumors should be surgically resected and examined carefully for an invasive component. In the absence of invasion, patient's survival is excellent, from 94 to 100%. For patients with an IPMN-associated invasive carcinoma, the prognosis overall is better than those with a de novo pancreatic ductal adenocarcinoma, with a 5-year survival of 40% to 60% in some series. However, no survival advantage can be demonstrated if the invasive component in an IPMN patient is that of the conventional tubular type (versus mucinous carcinoma). Several histomorphologic variants are recognized, although the clinical significance of this "subtyping" is not well defined.

Dysregulation of Wnt/β-catenin signaling in gastrointestinal cancers

Aberrant Wnt/β-catenin signaling is widely implicated in numerous malignancies, including cancers of the gastrointestinal tract. Dysregulation of signaling is traditionally attributed to mutations in Axin, adenomatous polyposis coli, and β-catenin that lead to constitutive hyperactivation of the pathway. However, Wnt/β-catenin signaling is also modulated through various other mechanisms in cancer, including cross talk with other altered signaling pathways. A more complex view of Wnt/β-catenin signaling and its role in gastrointestinal cancers is now emerging as divergent phenotypic outcomes are found to be dictated by temporospatial context and relative levels of pathway activation. This review summarizes the dysregulation of Wnt/β-catenin signaling in colorectal carcinoma, hepatocellular carcinoma, and pancreatic ductal adenocarcinoma, with particular emphasis on the latter two. We conclude by addressing some of the major challenges faced in attempting to target the pathway in the clinic.

Intraductal papillary mucinous neoplasm

Intraductal papillary mucinous neoplasm (IPMN) is a grossly visible (≥1 cm), mucin-producing neoplasm that arises in the main pancreatic duct and/or its branches. Patients with intraductal papillary mucinous neoplasm can present with symptoms caused by obstruction of the pancreatic duct system, or they can be asymptomatic. There are 3 clinical subtypes of intraductal papillary mucinous neoplasm: main duct, branch duct, and mixed. Five histologic types of intraductal papillary mucinous neoplasm are recognized: gastric foveolar type, intestinal type, pancreatobiliary type, intraductal oncocytic papillary neoplasm, and intraductal tubulopapillary neoplasm. Noninvasive intraductal papillary mucinous neoplasms are classified into 3 grades based on the degree of cytoarchitectural atypia: low-, intermediate-, and high-grade dysplasia. The most important prognosticator, however, is the presence or absence of an associated invasive carcinoma. Some main duct-intraductal papillary mucinous neoplasms progress into invasive carcinoma, mainly tubular adenocarcinoma (conventional pancreatic ductal adenocarcinoma) and colloid carcinoma. Branch duct-intraductal papillary mucinous neoplasms have a low risk for malignant transformation. Preoperative prediction of the malignant potential of an intraductal papillary mucinous neoplasm is of growing importance because pancreatic surgery has its complications, and many small intraductal papillary mucinous neoplasms, especially branch duct-intraductal papillary mucinous neoplasms, have an extremely low risk of progressing to an invasive cancer. Although most clinical decision making relies on imaging, a better understanding of the molecular genetics of intraductal papillary mucinous neoplasm could help identify molecular markers of high-risk lesions. When surgery is performed, intraoperative frozen section assessment of the pancreatic resection margin can guide the extent of resection. Intraductal papillary mucinous neoplasms are often multifocal, and surgically resected patients should be followed for metachronous disease.

Synchronous solid pseudopapillary neoplasm and intraductal papillary mucinous neoplasm of the pancreas: report of a case

Solid pseudopapillary neoplasm (SPN) of the pancreas, most commonly found in young female subjects, is a rare neoplasm with low potential for malignancy. We report an unusual case of a 66-year-old male patient who had a simultaneous malignant SPN and an intraductal papillary mucinous adenoma (IPMA) of the pancreas. The patient was admitted to our department for the evaluation of the main solid tumor with calcification and small multilocular cystic lesions apart from the main tumor in the pancreatic head. We performed pylorus-preserving pancreaticoduodenectomy to treat the calcified tumor and multilocular cystic lesions. The diagnosis of malignant SPN was confirmed on the basis of histological invasion to the adjacent structures. The separate cystic lesions were diagnosed as a branch-type IPMA. The synchronous occurrence of IPMA and SPN in the present case did not demonstrate that there were tumors maintained through the common abnormal Wnt signaling pathway by immunohistochemical study. To our knowledge, this is the first known case of synchronous SPN and IPMA of the pancreas.

Disabled-2 and Axin are concurrently colocalized and underexpressed in lung cancers

Disabled-2 expression is reduced in many cancers, suggesting that it is a potential tumor suppressor protein. To elucidate the role of Disabled-2 in lung cancer, we examined the expression of Disabled-2, the Disabled-2-binding protein Axin, and DNA methyltransferase-1 in lung cancer tissues and corresponding normal lung tissues using immunohistochemistry and Western blots. We also determined the subcellular localization of Axin and Disabled-2 in A549 cells using confocal immunofluorescence. Disabled-2 expression was significantly reduced in lung cancers and was colocalized and coexpressed with Axin (correlation coefficient = 0.321, P < .001 for cytoplasmic expression; correlation coefficient = 0.393, P < .001 for nuclear expression). Reduced nuclear Disabled-2 expression was correlated with the differentiation (P = .048) and TNM stage (P = .048) of the tumor. The cytoplasmic expression of Axin was also correlated with differentiation (P = .042), whereas the nuclear expression of Axin was correlated with both histologic type (P = .001) and TNM stage (P < .001) of lung cancers. Expression of DNA methyltransferase-1 was negatively correlated with the cytoplasmic expression of Axin (correlation coefficient = -0.244, P = .012) but positively correlated with the histologic type (P = .004), differentiation (P = .036), TNM stage (P = .044), and lymphatic metastasis (P = .011). Expressions of Disabled-2 and Axin were concurrently reduced and correlated with the malignant phenotype of lung cancers. Enhanced expression of DNA methyltransferase-1 correlated with the reduced expression of Axin and could be a marker for lung cancer development and progression.

Cystic precursors to invasive pancreatic cancer

Improvements in the sensitivity and quality of cross-sectional imaging have led to increasing numbers of patients being diagnosed with cystic lesions of the pancreas. In parallel, clinical, radiological, pathological and molecular studies have improved the systems for classifying these cysts. Patients with asymptomatic serous cystic neoplasms can be managed conservatively with regular monitoring; however, the clinical management of patients with intraductal papillary mucinous neoplasms and mucinous cystic neoplasms is far more challenging, as it is difficult to determine whether these lesions will progress to malignancy. Fortunately, prospective studies have helped to establish that proposed clinical and radiological criteria (the Sendai guidelines) can be used to guide the care of patients with cystic lesions of the pancreas. Despite this progress in imaging and clinical guidelines, sensitive and specific tests have not yet been developed that can reliably predict the histology and biological properties of a cystic lesion. Such biomarkers are urgently needed, as noninvasive precursors of pancreatic cancer are curable, while the vast majority of invasive pancreatic adenocarcinomas are not.

Intraductal papillary-mucinous neoplasia of the pancreas: Histopathology and molecular biology

Intraductal papillary-mucinous neoplasm (IPMN) of the pancreas is a clinically and morphologically distinctive precursor lesion of pancreatic cancer, characterized by gradual progression through a sequence of neoplastic changes. Based on the nature of the constituting neoplastic epithelium, degree of dysplasia and location within the pancreatic duct system, IPMNs are divided in several types which differ in their biological properties and clinical outcome. Molecular analysis and recent animal studies suggest that IPMNs develop in the context of a field-defect and reveal their possible relationship with other neoplastic precursor lesions of pancreatic cancer.

CABYR RNAi plasmid construction and NF-κB signal transduction pathway

AIM: To construct the CABYR RNAi plasmid and study its relation with the nuclear factor (NF)-κB signal transduction pathway.

METHODS: Human CABYR mRNA sequence was obtained from GenBank. The structure of cDNA sequence for the short hairpin RNA was BbsI + sense + loop + antisense + transcription terminator + KpnI + BamHI. A CABYR silencing plasmid was constructed and transfected into the human embryo cell line 293T. Quantitative real-time polymerase chain reaction was used to analyze CABYR and NF-κB gene expression.

RESULTS: The CABYR and NF-κB expressions were detected in 293T cells. The oligonucleotide (5’-GCTCAGATGTTAGGTAAAG-3’) efficiently silenced the expression of CABYR. The expression of NF-κB was not significantly affected by silencing CABYR (P = 0.743).

CONCLUSION: CABYR can be found in the human embryo cell line 293T. Cabyrmid 2 can efficiently silence its target, CABYR, indicating that CABYR is not related with the NF-κB signal transduction pathway.

Intraductal oncocytic papillary neoplasms of the pancreas and bile ducts: a description of five new cases and review based on a systematic survey of the literature

BACKGROUND

Intraductal oncocytic papillary neoplasms (IOPN) are rare tumors of the pancreatic and biliary ductal system. It is not absolutely clear if the molecular and clinicopathologic characteristics of IOPN differ significantly from other related lesions, namely intraductal papillary mucinous neoplasms (IPMN). Therefore it is not clear if it is reasonable to consider IOPN as a separate diagnostic and clinical entity.

METHODS

In order to describe the clinicopathologic characteristics of IOPN and to compare them with the IPMN profile, we performed a systematic review of the literature and additionally studied five previously unreported IOPN cases.

RESULTS

IOPN differ from IPMN by lack of K-ras gene mutations in all studied cases. Several differences in the clinical and biological profile between IOPN and IPMN exist, but they are of quantitative rather than of qualitative nature. Additionally, pancreaticobiliary or gastric-foveolar IPMN components may coexist with IOPN component within a single lesion, which suggests at least a partial relation of the pathogenetic pathways of IPMN and IOPN. Importantly, the pathogenesis of accumulation of mitochondria and oxyphilic appearance of IOPN remains unknown.

CONCLUSIONS

At present, there are no reliable criteria other than histopathological picture and K-ras gene status to differentiate IOPN from IPMN. In particular, no clear differences in optimal treatment options and prognosis between these tumors are known. Further studies are needed to clarify the biology of IOPN and to establish their position in clinicopathologic classifications of pancreatic tumors.

CD44v6 expression in intraductal papillary mucinous neoplasms of the pancreas

OBJECTIVES

The purpose of this study was to examine CD44v6 expression in intraductal papillary mucinous neoplasms (IPMNs) and clarify the role of CD44v6 in progression, invasion, metastasis, and morphogenesis of IPMNs.

METHODS

One hundred fifty-one samples of IPMNs and 30 normal controls were subjected to immunohistochemical analysis for CD44v6. The IPMNs were divided into 4 groups according to the grade of atypia (adenoma, borderline IPMN, noninvasive carcinoma, and invasive carcinoma) and 5 subtypes according to histological phenotype (gastric, intestinal, pancreatobiliary, oncocytic, and unclassified). Correlations were investigated between CD44v6 expression and clinicopathological characteristics including grade of atypia, subtype, lymph node metastasis, and invasion pattern.

RESULTS

Whereas normal ductal epithelium did not express CD44v6, CD44v6 expression was observed from the early stage of IPMNs and up-regulated in the progression of IPMNs to invasive carcinoma. CD44v6 expression in intestinal-type IPMNs was significantly lower compared with that in other subtypes. Whereas no correlation was observed between lymph node metastasis and CD44v6 expression in invasive IPM carcinomas, the invasion pattern was significantly correlated to CD44v6 expression.

CONCLUSIONS

The present data indicate that CD44v6 expression determines the morphology and aggressiveness of IPMNs and is involved in development and invasion of IPMNs.

Immunohistochemical analyses of E-cadherin, beta-catenin, CD44s, and CD44v6 expressions, and Ki-67 labeling index in intraductal papillary mucinous neoplasms of the pancreas and associated invasive carcinomas

We examined the expressions of adhesion molecules (E-cadherin, beta-catenin, CD44s, and CD44v6) and Ki-67 labeling index (Ki-67 LI) in low- and moderate-grade dysplasia and invasive carcinoma components in ten noninvasive intraductal papillary mucinous neoplasms (IPMNs) of the pancreas and eight invasive carcinomas associated with IPMNs of the pancreas using immunohistochemical methods. There was no significant difference in regard to the proportion of components expressing either E-cadherin or beta-catenin in more than 70% of the tumor cells between the low- and moderate-grade dysplasia components. In contrast, the proportion of those in invasive carcinoma components was significantly lower than in low- or moderate-grade dysplasia components. Also, there was no significant difference in the proportion of components expressing CD44s or CD44v6 in more than 5% of tumor cells among low-grade dysplasia, moderate-grade dysplasia, and invasive carcinoma components. In contrast, the Ki-67 LI values increased in the order of low-grade dysplasia, moderate-grade dysplasia, and invasive carcinoma components, with significant differences among them. The present results indicate that carcinoma components are associated with a decrease in tumor cells expressing E-cadherin and beta-catenin and have the highest proliferative activity.

Global genomic analysis of intraductal papillary mucinous neoplasms of the pancreas reveals significant molecular differences compared to ductal adenocarcinoma

OBJECTIVE

To determine whether intraductal papillary mucinous neoplasms of the pancreas (IPMNs) have a different genetic background compared with ductal adenocarcinoma (PDAC).

SUMMARY BACKGROUND DATA

The biologic and clinical behavior of IPMNs and IPMN-associated adenocarcinomas is different from PDAC in having a less aggressive tumor growth and significantly improved survival. Up to date, the molecular mechanisms underlying the clinical behavior of IPMNs are incompletely understood.

METHODS

128 cystic pancreatic lesions were prospectively identified during the course of 2 years. From the corresponding surgical specimens, 57 IPMNs were separated and subdivided by histologic criteria into those with low-grade dysplasia, moderate dysplasia, high-grade dysplasia, and invasive cancer. Twenty specimens were suitable for DNA isolation and subsequent performance of array CGH.

RESULTS

While none of the IPMNs with low-grade dysplasia displayed detectable chromosomal aberrations, IPMNs with moderate and high-grade dysplasia showed frequent copy number alterations. Commonly lost regions were located on chromosome 5q, 6q, 10q, 11q, 13q, 18q, and 22q. The incidence of loss of chromosome 5q, 6q, and 11q was significantly higher in IPMNs with high-grade dysplasia or invasion compared with PDAC. Ten of 13 IPMNs with moderate dysplasia or malignancy had loss of part or all of chromosome 6q, with a minimal deleted region between linear positions 78.0 and 130.0.

CONCLUSIONS

This study is the first to use array CGH to characterize IPMNs. Recurrent cytogenetic alterations were identified and were different than those described in PDAC. Array CGH may help distinguish between these 2 entities and give insight into the differences in their biology and prognosis.

Precursor lesions of pancreatic cancer

This review article describes morphological aspects, gene abnormalities, and mucin expression profiles in precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm (MCN) of the pancreas, as well as their relation to pancreatic ductal adenocarcinoma (PDAC). The gene abnormalities in precursors of PDAC are summarized as follows: (1) KRAS mutation and p16/CDKN2A inactivation are early events whose frequencies increase with the dysplasia grade in both PanIN and IPMN; (2) TP53 mutation and SMAD4/DPC4 inactivation are late events observed in PanIN3 or carcinomatous change of IPMN in both PanIN and IPMN, although the frequency of the TP53 mutation is lower in IPMN than in PDAC; and (3) also in MCN, KRAS mutation is an early event whose frequency increases with the dysplasia grade, whereas TP53 mutation and SMAD4/DPC4 inactivation are evident only in the carcinoma. The mucin expression profiles in precursors of PDAC are summarized as follows: (1) MUC1 expression increases with the PanIN grade, and is high in PDAC; (2) the expression pattern of MUC2 differs markedly between the major subtypes of IPMN with different malignancy potentials (i.e., IPMN-intestinal type with MUC2+ expression and IPMN-gastric type with MUC2- expression); (3) MUC2 is not expressed in any grade of PanINs, which is useful for differentiating PanIN from intestinal-type IPMN; (4) de novo expression of MUC4, which appears to increase with the dysplasia grade; and (5) high de novo expression of MUC5AC in all grades of PanINs, all types of IPMN, MCN, and PDAC.

Effect of transforming growth factor β1 on cell cycle-associated genes in BxPC-3

AIM: To further investigate the mechanism underlying the cell cycle-associated gene expression regulated by exogeneous TGFβ1 in BxPC-3 pancreatic cancer cells.

METHODS: Alterations of 24 cell cycle-associated genes were determined using a specially designed gene chip in BxPC-3 cells treated with 2 μg/L TGFβ1 for 72 h. Those which were not interfered were taken as controls.

RESULTS: After the intervention of 2.0 μg/L TGFβ1, of the 24 genes, three genes were found unchanged, 3 genes (namely, p27KIP1, DMTF1 and TIEG) were up-regulated, 17 genes were down-regulated and only one was deleted for characterization due to an experimental error. Many a gene was associated with the G₁/S cell cycle transition (e.g., GSPT1, ASK, CDK4, SKP2, cyclin C), some of them were transcription factors (e.g., E2F3 and E2F5), and TRAD was a serine/threonine kinase with Dbl- and pleckstrin homology domains.

CONCLUSION: Tissue microarray analysis revealed multiple alterations of the cell cycle-associated genes that were regulated by TGFβ1. This finding indicates the existence of cross-talking between the Smad-dependent and Smad-independent pathways of TGFβ1, which may mediate the growth-inhibitory effect of TGFβ1 in pancreatic carcinoma.

Frequent accumulation of nuclear E-cadherin and alterations in the Wnt signaling pathway in esophageal squamous cell carcinomas

Esophageal squamous cell carcinoma is frequently associated with poor prognosis, as a result of high levels of lymph node metastasis. So far, very few genetic abnormalities have been associated with this disease, and its molecular etiology remains largely unknown. To assess whether the Wnt pathway contributes to esophageal squamous cell carcinoma, we characterized the expression and subcellular localization of the key Wnt signaling components in all 30 cases of esophageal squamous cell carcinomas analyzed. We found abnormal expression and/or localization in glycogen synthase kinase-3 alpha/beta (34%), Axin2 (48%), alpha-catenin (31%), MYC (73%) and cyclin D1 in 46% of cases. Only 13% of tumors showed nuclear accumulation of beta-catenin. By contrast, 60% showed nuclear expression of E-cadherin using an antibody that recognizes the cytoplasmic domain of E-cadherin. When the same tumors were stained with antibody raised against the extracellular domain of E-cadherin, the expression was lost. A direct correlation was found between nuclear E-cadherin and the increased nuclear cyclin D1, one of the AP-1 target genes in these tumors. By transfection experiments, the cytoplasmic portion of E-cadherin was found to activate the AP-1 transcription factor pathway and induced cyclin D1 promoter activity, but beta-catenin/Tcf transcription activity was unaffected. Nuclear expression of E-cadherin was also detected in tumors other than squamous cell carcinoma, including pancreatic and colon cancers, albeit at lower frequency. Nuclear accumulation of a portion of E-cadherin in esophageal squamous cell carcinoma and the other types of tumors indicates that, in addition to the previously implicated tumor suppressor activity of E-cadherin, modified forms of this glycoprotein might also play a role in growth promotion.

Oncocytic papillary neoplasms of the biliary tract: a clinicopathological, mucin core and Wnt pathway protein analysis of four cases

AIMS

Oncocytic change in papillary neoplasms of the biliary tract is a very uncommon finding with little known about pathogenesis, immunophenotype and prognosis, especially in comparison to similar lesions in the pancreatic ductal system. We report four cases of oncocytic biliary intraductal papillary neoplasms (IPNs), highlighting the clinicopathological characteristics of these tumours, the immunohistochemical profile with regard to Wnt pathway proteins and mucin core protein (MUC) status, and compare these findings with the oncocytic variant of intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

Four cases of oncocytic IPN of the extrapancreatic, biliary tree (two with accompanying invasive carcinomas) were examined for mucin profiles and Wnt signalling proteins. The cases were stained for: beta-catenin, c-myc, glutathione synthase kinase (GSK), E-cadherin, cyclin D1, and adenomatous polyposis coli (APC), and MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B and MUC6, using standard immunohistochemistry.

RESULTS

The cases occurred in three males and one female, ranging in age from 59 to 81 years. The lesions caused obstructive symptoms related to the biliary tree as well as non-specific abdominal symptoms. Typically, cystic lesions were noted grossly. All four of the IPNs were composed of distinctive oncocytic cells. The invasive carcinomas accompanying two of the cases were also composed of oncocytes. None of the cases showed aberrant expression of the Wnt signalling proteins, although cyclin D1 was markedly over-expressed in all four cases. Three of four cases showed the following mucin profile: MUC3, MUC4, MUC5AC, MUC5B and MUC6 positive.

CONCLUSIONS

The Wnt pathway proteins (especially beta-catenin and E-cadherin) are expressed normally in oncocytic variants of intraductal papillary neoplasms of the biliary tree, and the mucin profile is similar to their counterparts in the pancreas.

Downregulated expression of metallothionein and its clinicopathological significance in hepatocellular carcinoma

AIM

Metallothionein (MT) protein is related to different stages of development and progression of various tumors in humans. The aim of the present study was to investigate expression and localization of MT and their association with clinicopathological characteristics in hepatocellular carcinoma (HCC).

METHODS

Histological specimens of 400 HCC with corresponding non-cancerous liver tissues were stained for MT (E9), P53 and Ki-67 by immunohistochemical staining using tissue microarrays. RNA expression of MT-1X and MT-2A isoforms was determined by real-time reverse transcription-polymerase chain reaction in a set of independent samples of 161 HCC.

RESULTS

Downregulated expression of MT at both mRNA and protein levels was detected in HCC, compared with non-cancerous liver tissues. The frequencies of MT positivity were significantly lower in cases with positive hepatitis B surface antigen than in those with negative hepatitis B surfaceantigen (P = 0.042). The positive rate of MT expression was more frequent in tumors </=2 cm than in tumors >2 cm in diameter (P = 0.007). There was a tendency for MT expression to decrease with the progression of histological grade. Mainly nuclear expression of MT correlated with poorly differentiated HCC. No statistical correlation was found between P53, Ki-67 and MT expression.

CONCLUSIONS

Downregulated expression of MT in HCC may play a role in hepatocarcinogenesis and be a marker of hepatocellular differentiation. Hepatitis B virus infection may be correlated to downregulated expression of MT. The mainly nuclear MT immunostaining may reflect an aggressive behavior in poorly differentiated HCC.

Cystic neoplasms of the exocrine pancreas

The increasing use of radiological imaging has led to greater detection of small and asymptomatic cystic lesions of the pancreas. Most are resectable, but not all are neoplastic. This review provides an update on the histopathology, immunohistochemistry, molecular biology, pathogenesis and management of cystic neoplasms of the exocrine pancreas. These include the serous, the mucinous cystic, the intraductal papillary mucinous and the solid pseudopapillary neoplasms. Recently reported variants are described and very rare cystic variants of other pancreatic epithelial and mesenchymal neoplasms are briefly mentioned.

Mucin expression profile in pancreatic cancer and the precursor lesions

In this review article, we demonstrate the mucin expression profile in normal tissue, invasive ductal carcinoma (IDC), two subtypes of intraductal papillary-mucinous neoplasm (IPMN dark cell type and IPMN clear cell type), pancreatic intraepithelial neoplasia (PanIN), and mucinous cystic neoplasm (MCN) of the pancreas. In MUC1, there are various glycoforms, such as poorly glycosylated MUC1, sialylated MUC1, and fully glycosylated MUC1. IDCs showed high expression of all the glycoforms of MUC1. IPMNs dark cell type showed no expression or low expression of all the glycoforms of MUC1. IPMNs clear cell type showed low expression of poorly glycosylated MUC1, but expression of sialylated MUC1 and fully glycosylated MUC1. Expression of MUC2 was negative in IDCs, high in IPMNs dark cell type and low in IPMNs clear cell type. MUC5AC was highly expressed in IDCs, IPMNs dark cell type, and IPMNs clear cell type. MUC6 expression was higher in IPMNs clear cell type than in IDCs and IPMNs dark cell type. Our recent study demonstrated that high expression of MUC4 in IDCs is correlated with a poor outcome for patients. In PanINs, expression of both MUC5AC and MUC6 are an early event, whereas up-regulation of MUC1 is a late event. MCNs do not look as if they will show a specific mucin expression profile according to the literature review.