Activated wnt signaling in stroma contributes to development of pancreatic mucinous cystic neoplasms

BACKGROUND & AIMS

Pancreatic mucinous cystic neoplasm (MCN), a cystic tumor of the pancreas that develops most frequently in women, is a potential precursor to pancreatic ductal adenocarcinoma. MCNs develop primarily in the body and tail of the pancreas and are characterized by the presence of a mucinous epithelium and ovarian-like subepithelial stroma. We investigated the involvement of Wnt signaling in KRAS-mediated pancreatic tumorigenesis and development of MCN in mice, and Wnt activation in human MCN samples.

METHODS

LSL-Kras(G12D), Ptf1a-cre mice were crossed with elastase-tva mice to allow for introduction of genes encoded by the replication-competent avian sarcoma-leukosis virus long-terminal repeat with splice acceptor viruses to pancreatic acinar cells and acinar cell progenitors, postnatally and sporadically. Repeat with splice acceptor viruses that expressed Wnt1 were delivered to the pancreatic epithelium of these mice; pancreatic lesions were analyzed by histopathology and immunohistochemical analyses. We analyzed levels of factors in Wnt signaling pathways in 19 MCN samples from patients.

RESULTS

Expression of Wnt1 in the pancreatic acinar cells and acinar cell progenitors of female mice led to development of unilocular or multilocular epithelial cysts in the pancreas body and tail, similar to MCN. The cystic lesions resembled the estrogen receptor- and progesterone receptor-positive ovarian-like stroma of MCN, but lacked the typical mucinous epithelium. Activated Wnt signaling, based on nuclear localization of β-catenin, was detected in the stroma but not cyst epithelium. Wnt signaling to β-catenin was found to be activated in MCN samples from patients, within the ovarian-like stroma, consistent with the findings in mice.

CONCLUSIONS

Based on studies of mice and pancreatic MCN samples from patients, the canonical Wnt signaling pathway becomes activated and promotes development of the ovarian-like stroma to contribute to formation of MCNs.

MicroRNAs cooperatively inhibit a network of tumor suppressor genes to promote pancreatic tumor growth and progression

BACKGROUND & AIMS

There has not been a broad analysis of the combined effects of altered activities of microRNAs (miRNAs) in pancreatic ductal adenocarcinoma (PDAC) cells, and it is unclear how these might affect tumor progression or patient outcomes.

METHODS

We combined data from miRNA and messenger RNA (mRNA) expression profiles and bioinformatic analyses to identify an miRNA-mRNA regulatory network in PDAC cell lines (PANC-1 and MIA PaCa-2) and in PDAC samples from patients. We used this information to identify miRNAs that contribute most to tumorigenesis.

RESULTS

We identified 3 miRNAs (MIR21, MIR23A, and MIR27A) that acted as cooperative repressors of a network of tumor suppressor genes that included PDCD4, BTG2, and NEDD4L. Inhibition of MIR21, MIR23A, and MIR27A had synergistic effects in reducing proliferation of PDAC cells in culture and growth of xenograft tumors in mice. The level of inhibition was greater than that of inhibition of MIR21 alone. In 91 PDAC samples from patients, high levels of a combination of MIR21, MIR23A, and MIR27A were associated with shorter survival times after surgical resection.

CONCLUSIONS

In an integrated data analysis, we identified functional miRNA-mRNA interactions that contribute to growth of PDACs. These findings indicate that miRNAs act together to promote tumor progression; therapeutic strategies might require inhibition of several miRNAs.

Pancreatic ductal adenocarcinoma radiology reporting template: consensus statement of the society of abdominal radiology and the american pancreatic association

Pancreatic ductal adenocarcinoma is an aggressive malignancy with a high mortality rate. Proper determination of the extent of disease on imaging studies at the time of staging is one of the most important steps in optimal patient management. Given the variability in expertise and definition of disease extent among different practitioners as well as frequent lack of complete reporting of pertinent imaging findings at radiologic examinations, adoption of a standardized template for radiology reporting, using universally accepted and agreed on terminology for solid pancreatic neoplasms, is needed. A consensus statement describing a standardized reporting template authored by a multi-institutional group of experts in pancreatic ductal adenocarcinoma that included radiologists, gastroenterologists, and hepatopancreatobiliary surgeons was developed under the joint sponsorship of the Society of Abdominal Radiologists and the American Pancreatic Association. Adoption of this standardized imaging reporting template should improve the decision-making process for the management of patients with pancreatic ductal adenocarcinoma by providing a complete, pertinent, and accurate reporting of disease staging to optimize treatment recommendations that can be offered to the patient. Standardization can also help to facilitate research and clinical trial design by using appropriate and consistent staging by means of resectability status, thus allowing for comparison of results among different institutions.

DCLK1 marks a morphologically distinct subpopulation of cells with stem cell properties in preinvasive pancreatic cancer

BACKGROUND & AIMS

As in other tumor types, progression of pancreatic cancer may require a functionally unique population of cancer stem cells. Although such cells have been identified in many invasive cancers, it is not clear whether they emerge during early or late stages of tumorigenesis. Using mouse models and human pancreatic cancer cell lines, we investigated whether preinvasive pancreatic neoplasia contains a subpopulation of cells with distinct morphologies and cancer stem cell-like properties.

METHODS

Pancreatic tissue samples were collected from the KC(Pdx1), KPC(Pdx1), and KC(iMist1) mouse models of pancreatic intraepithelial neoplasia (PanIN) and analyzed by confocal and electron microscopy, lineage tracing, and fluorescence-activated cell sorting. Subpopulations of human pancreatic ductal adenocarcinoma (PDAC) cells were similarly analyzed and also used in complementary DNA microarray analyses.

RESULTS

The microtubule regulator DCLK1 marked a morphologically distinct and functionally unique population of pancreatic cancer-initiating cells. These cells displayed morphological and molecular features of gastrointestinal tuft cells. Cells that expressed DCLK1 also expressed high levels of ATAT1, HES1, HEY1, IGF1R, and ABL1, and manipulation of these pathways in PDAC cell lines inhibited their clonogenic potential. Pharmacological inhibition of γ-secretase activity reduced the abundance of these cells in murine PanIN in a manner that correlated with inhibition of PanIN progression.

CONCLUSIONS

Human PDAC cells and pancreatic neoplasms in mice contain morphologically and functionally distinct subpopulations that have cancer stem cell-like properties. These populations can be identified at the earliest stages of pancreatic tumorigenesis and provide new cellular and molecular targets for pancreatic cancer treatment and/or chemoprevention.

Macrophages increase the resistance of pancreatic adenocarcinoma cells to gemcitabine by upregulating cytidine deaminase

Tumor-associated macrophages play a central role in tumor progression and metastasis. Macrophages can also promote the resistance of malignant cells to chemotherapy by stimulating the upregulation of cytidine deaminase, an intracellular enzyme that catabolizes the active form of gemcitabine. Targeting macrophage-dependent chemoresistance may reduce tumor-associated morbidity and mortality.

A high-fat diet activates oncogenic Kras and COX2 to induce development of pancreatic ductal adenocarcinoma in mice

BACKGROUND & AIMS

Obesity is a risk factor for pancreatic ductal adenocarcinoma (PDAC), but it is not clear how obesity contributes to pancreatic carcinogenesis. The oncogenic form of KRAS is expressed during early stages of PDAC development and is detected in almost all of these tumors. However, there is evidence that mutant KRAS requires an additional stimulus to activate its full oncogenic activity and that this stimulus involves the inflammatory response. We investigated whether the inflammation induced by a high-fat diet, and the accompanying up-regulation of cyclooxygenase-2 (COX2), increases Kras activity during pancreatic carcinogenesis in mice.

METHODS

We studied mice with acinar cell-specific expression of KrasG12D (LSL-Kras/Ela-CreERT mice) alone or crossed with COX2 conditional knockout mice (COXKO/LSL-Kras/Ela-CreERT). We also studied LSL-Kras/PDX1-Cre mice. All mice were fed isocaloric diets with different amounts of fat, and a COX2 inhibitor was administered to some LSL-Kras/Ela-CreERT mice. Pancreata were collected from mice and analyzed for Kras activity, levels of phosphorylated extracellular-regulated kinase, inflammation, fibrosis, pancreatic intraepithelial neoplasia (PanIN), and PDACs.

RESULTS

Pancreatic tissues from LSL-Kras/Ela-CreERT mice fed high-fat diets (HFDs) had increased Kras activity, fibrotic stroma, and numbers of PanINs and PDACs than LSL-Kras/Ela-CreERT mice fed control diets; the mice fed the HFDs also had shorter survival times than mice fed control diets. Administration of a COX2 inhibitor to LSL-Kras/Ela-CreERT mice prevented these effects of HFDs. We also observed a significant reduction in survival times of mice fed HFDs. COXKO/LSL-Kras/Ela-CreERT mice fed HFDs had no evidence for increased numbers of PanIN lesions, inflammation, or fibrosis, as opposed to the increases observed in LSL-Kras/Ela-CreERT mice fed HFDs.

CONCLUSIONS

In mice, an HFD can activate oncogenic Kras via COX2, leading to pancreatic inflammation and fibrosis and development of PanINs and PDAC. This mechanism might be involved in the association between risk for PDAC and HFDs.

cAMP inhibits migration, ruffling and paxillin accumulation in focal adhesions of pancreatic ductal adenocarcinoma cells: effects of PKA and EPAC

We demonstrated that increasing intracellular cAMP concentrations result in the inhibition of migration of PANC-1 and other pancreatic ductal adenocarcinoma (PDAC) cell types. The rise of cAMP was accompanied by rapid and reversible cessation of ruffling, by inhibition of focal adhesion turnover and by prominent loss of paxillin from focal adhesions. All these phenomena develop rapidly suggesting that cAMP effectors have a direct influence on the cellular migratory apparatus. The role of two primary cAMP effectors, exchange protein activated by cAMP (EPAC) and protein kinase A (PKA), in cAMP-mediated inhibition of PDAC cell migration and migration-associated processes was investigated. Experiments with selective activators of EPAC and PKA demonstrated that the inhibitory effect of cAMP on migration, ruffling, focal adhesion dynamics and paxillin localisation is mediated by PKA, whilst EPAC potentiates migration.

Effect of preoperative renal insufficiency on postoperative outcomes after pancreatic resection: a single institution experience of 1,061 consecutive patients

BACKGROUND

Chronic kidney disease (CKD) is known to adversely affect cardiac and vascular surgery outcomes. We examined the effect of preoperative renal insufficiency on postoperative outcomes after pancreatic resection.

STUDY DESIGN

All patients who underwent pancreatic resection between January 2005 and July 2012 were identified. Glomerular filtration rate (eGFR) was estimated by the Modification of Diet in Renal Disease formula. Severe CKD (stages 4-5) was defined as eGFR < 30 mL/min/1.73 m(2). Renal function also was analyzed using serum creatinine (sCr) dichotomized at 1.8 mg/dL. Primary outcomes were any complication, major complications, and respiratory failure. Multivariate models for each endpoint were constructed by including all variables with p value ≤ 0.10 on univariate analysis.

RESULTS

There were 1,061 patients identified; 709 underwent pancreaticoduodenectomy, 307 distal pancreatectomy, and 45 central or total pancreatectomy. Median sCr value was 0.86 mg/dL (range 0.30 to 14.1 mg/dL). Eighteen patients (1.7%) had severe CKD and 31 (2.9%) had sCr ≥ 1.8 mg/dL. Complications occurred in 622 patients (58.6%), major complications in 198 (18.7%), and respiratory failure in 48 (4.5%). Both severe CKD and sCr ≥ 1.8 mg/dL were associated with any complication, major complications, and respiratory failure on univariate analysis. On multivariate analysis, severe CKD was associated with increased complications (odds ratio [OR] 5.5; 95% CI 1.3 to 25.5; p = 0.02) and respiratory failure (OR 6.1; 95% CI 1.8 to 20.5; p = 0.03), but not major complications. Using sCr ≥ 1.8 mg/dL as a surrogate marker for renal insufficiency, patients with sCr ≥ 1.8 mg/dL had increased risk of any complication (OR 3.5; 95% CI 1.3 to 9.3; p = 0.01), major complications (OR 2.2; 95% CI 1.04 to 4.8; p = 0.04), and respiratory failure (OR 4.7; 95% CI 1.8 to 12.6; p = 0.002).

CONCLUSIONS

Few patients with significant renal insufficiency are candidates for pancreatic resection. Severe CKD (stages 4-5) is associated with increased risk of complication and respiratory failure. Serum creatinine ≥ 1.8 mg/dL may serve as a useful marker of renal insufficiency and identifies patients at significantly increased risk of any complication, major complication, and respiratory failure after pancreatic resection.

Genetic alterations associated with progression from pancreatic intraepithelial neoplasia to invasive pancreatic tumor

BACKGROUND & AIMS

Increasing grade of pancreatic intraepithelial neoplasia (PanIN) has been associated with progression to pancreatic ductal adenocarcinoma (PDAC). However, the mechanisms that control progression from PanINs to PDAC are not well understood. We investigated the genetic alterations involved in this process.

METHODS

Genomic DNA samples from laser-capture microdissected PDACs and adjacent PanIN2 and PanIN3 lesions from 10 patients with pancreatic cancer were analyzed by exome sequencing.

RESULTS

Similar numbers of somatic mutations were identified in PanINs and tumors, but the mutational load varied greatly among cases. Ten of the 15 isolated PanINs shared more than 50% of somatic mutations with associated tumors. Mutations common to tumors and clonally related PanIN2 and PanIN3 lesions were identified as genes that could promote carcinogenesis. KRAS and TP53 frequently were altered in PanINs and tumors, but few other recurrently modified genes were detected. Mutations in DNA damage response genes were prevalent in all samples. Genes that encode proteins involved in gap junctions, the actin cytoskeleton, the mitogen-activated protein kinase signaling pathway, axon guidance, and cell-cycle regulation were among the earliest targets of mutagenesis in PanINs that progressed to PDAC.

CONCLUSIONS

Early stage PanIN2 lesions appear to contain many of the somatic gene alterations required for PDAC development.

Numb regulates acinar cell dedifferentiation and survival during pancreatic damage and acinar-to-ductal metaplasia

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDA) is a leading cause of cancer-related death. Through the process of acinar-to-ductal metaplasia (ADM), pancreatic acinar cells give rise to pancreatic intraepithelial neoplasia (PanIN), the most common precursor of PDA. However, even when Kras is activated in a majority of acinar cells, ADM and subsequent development of PanINs is inefficient in the absence of additional stresses. Numb regulates cell junctions, integrins, and the activity of embryonic signaling pathways; therefore, we investigated its effects on acinar cell dedifferentiation, regeneration, and metaplasia.

METHODS

We used mouse models of pancreatic regeneration and PDA as well as mice with loss-of-function alleles of Numb (p48Cre/p48Cre(ER);Numb(f/f) and p48Cre/p48Cre(ER);Kras(G12D);Numb(f/f) mice) to study the roles of Numb in pancreatic regeneration and ADM.

RESULTS

Loss of Numb resulted in premature dedifferentiation of acinar cells in response to injury due to administration of the cholecystokinin analogue cerulein and interfered with acinar cell regeneration. Numb was found to regulate multiple signaling pathways in acinar cells during cerulein-induced pancreatitis. Disruption of Numb accelerated and destabilized ADM in the context of oncogenic Kras (in p48Cre;Kras(G12D);Numb(f/f) and p48Cre(ER);Kras(G12D);Numb(f/f) mice).

CONCLUSIONS

Numb is an important regulator of acinar cell differentiation and viability during metaplasia. In mice with pancreatitis or pancreatic injury, elimination of Numb causes dedifferentiated acinar cells to undergo apoptosis, and this is not mitigated by oncogenic Kras.

Activated pancreatic stellate cells sequester CD8+ T cells to reduce their infiltration of the juxtatumoral compartment of pancreatic ductal adenocarcinoma

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a prominent desmoplastic microenvironment that contains many different immune cells. Activated pancreatic stellate cells (PSCs) contribute to the desmoplasia. We investigated whether distinct stromal compartments are differentially infiltrated by different types of immune cells.

METHODS

We used tissue microarray analysis to compare immune cell infiltration of different pancreaticobiliary diseased tissues (PDAC, ampullary carcinoma, cholangiocarcinoma, mucinous cystic neoplasm, chronic inflammation, and chronic pancreatitis) and juxtatumoral stromal (<100 μm from tumor) and panstromal compartments. We investigated the association between immune infiltrate and patient survival times. We also analyzed T-cell migration and tumor infiltration in LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mice and the effects of all-trans retinoic acid (ATRA) on these processes.

RESULTS

Juxtatumoral compartments in PDAC samples from 2 independent groups of patients contained increased numbers of myeloperoxidase(+) and CD68(+) cells compared with panstromal compartments. However, juxtatumoral compartments of PDACs contained fewer CD8(+), FoxP3(+), CD56(+), or CD20(+) cells than panstromal compartments, a distinction absent in ampullary carcinomas and cholangiocarcinomas. Patients with PDACs that had high densities of CD8(+) T cells in the juxtatumoral compartment had longer survival times than patients with lower densities. In KPC mice, administration of ATRA, which renders PSCs quiescent, increased numbers of CD8(+) T cells in juxtatumoral compartments. We found that activated PSCs express cytokines, chemokines, and adhesion molecules that regulate T-cell migration. In vitro migration assays showed that CD8(+) T cells, from patients with PDAC, had increased chemotaxis toward activated PSCs, which secrete CXCL12, compared with quiescent PSCs or tumor cells. These effects could be reversed by knockdown of CXCL12 or treatment of PSCs with ATRA.

CONCLUSIONS

Based on studies of human PDAC samples and KPC mice, activated PSCs appear to reduce migration of CD8(+) T cells to juxtatumoral stromal compartments, preventing their access to cancer cells. Deregulated signaling by activated PSCs could prevent an effective antitumor immune response.

A gene expression signature of epithelial tubulogenesis and a role for ASPM in pancreatic tumor progression

BACKGROUND & AIMS

Many patients with pancreatic ductal adenocarcinoma (PDAC) develop recurrent or metastatic diseases after surgery, so it is important to identify those most likely to benefit from aggressive therapy. Disruption of tissue microarchitecture is an early step in pancreatic tumorigenesis and a parameter used in pathology grading of glandular tumors. We investigated whether changes in gene expression during pancreatic epithelial morphogenesis were associated with outcomes of patients with PDAC after surgery.

METHODS

We generated architectures of human pancreatic duct epithelial cells in a 3-dimensional basement membrane matrix. We identified gene expression profiles of the cells during different stages of tubular morphogenesis (tubulogenesis) and of PANC-1 cells during spheroid formation. Differential expression of genes was confirmed by immunoblot analysis. We compared the gene expression profile associated with pancreatic epithelial tubulogenesis with that of PDAC samples from 27 patients, as well as with their outcomes after surgery.

RESULTS

We identified a gene expression profile associated with tubulogenesis that resembled the profile of human pancreatic tissue with differentiated morphology and exocrine function. Patients with PDACs with this profile fared well after surgery. Based on this profile, we established a 6-28 gene tubulogenesis-specific signature that accurately determined the prognosis of independent cohorts of patients with PDAC (total n = 128; accuracy = 81.2%-95.0%). One gene, ASPM, was down-regulated during tubulogenesis but up-regulated in human PDAC cell lines and tumor samples; up-regulation correlated with patient outcomes (Cox regression P = .0028). Bioinformatic, genetic, biochemical, functional, and clinical correlative studies showed that ASPM promotes aggressiveness of PDAC by maintaining Wnt-β-catenin signaling and stem cell features of PDAC cells.

CONCLUSIONS

We identified a gene expression profile associated with pancreatic epithelial tubulogenesis and a tissue architecture-specific signature of PDAC cells that is associated with patient outcomes after surgery.

Phosphorylation of STAT3 correlates with HER2 status, but not with survival in pancreatic ductal adenocarcinoma

Activation of signal-transcriptional factor signal transducer and activator of transcription 3 (STAT3) is associated with more aggressive behaviour in a variety of human malignancies. As selective STAT3 inhibitors exist, this protein might represent a novel therapeutic target. Although STAT3 seems to play an important role in progression of pancreatic ductal carcinoma (PDAC), only few data on this subject exist. The aim of our study was the investigation of STAT3 activation and its correlation with its possible regulator HER2. Expression of tyrosine-705 phosphorylated STAT3 (pSTAT3) was determined immunohistochemically in 79 PDACs. HER2 status assessed by immunohistochemistry and double colour silver in situ hybridization was available from a previous study. PSTAT3 expression was seen in 33 (41.8%) patients. Six patients were scored as HER2 positive having strong correlation with pSTAT3 expression (p = 0.004, Fisher's exact test). No association of pSTAT3 expression with patients' age, tumour staging and grading, perineural invasion of tumour cells or survival time was seen. pSTAT3 is frequently expressed in PDAC. Nevertheless, its immediate clinical relevance seems to be low. However, further research needs to determine whether STAT3 status in PDAC is predictive for the response to novel targeting therapies.

Expression of microRNA-218 in human pancreatic ductal adenocarcinoma and its correlation with tumor progression and patient survival

BACKGROUND

Our aim was to analyze clinicopathologic and prognostic values of microRNA (miR)-218 in pancreatic ductal adenocarcinima (PDAC).

METHODS

TaqMan quantitative RT-PCR was used to determine the expression of miR-218 in human PDAC cells and tissue samples. The association of miR-218 expression with clinicopathologic variables was analyzed. Kaplan-Meier survival analysis was performed to analyze the association of miR-218 expression with recurrence-free survival or overall survival of patients. Univariate and multivariate Cox regression analyses were performed.

RESULTS

The relative level of miR-218 in PDAC cells was significantly lower than that in normal human pancreatic duct epithelial cell line. Also, the mean level of miR-218 in PDAC tissues was significantly lower than that in normal pancreatic tissues. Statistical analyses indicated that low miR-218 expression was closely associated with poor tumor differentiation, advanced tumor stage, higher incidence of lymph node metastasis, and tumor recurrence. Kaplan-Meier survival analyses showed that patients with low miR-218 expression had lower recurrence-free and overall survival than those with high miR-218 expression. Univariate and multivariate Cox regression analyses showed that miR-218 might be an independent prognostic factor.

CONCLUSION

Reduced miR-218 in PDAC tissues was correlated with tumor progression, and might be an independent poor prognostic factor for patients.

The stromal compartments in pancreatic cancer: are there any therapeutic targets?

Pancreatic ductal adenocarcinoma (PDAC) is characterised by an abundant stromal response also known as a desmoplastic reaction. Pancreatic Stellate Cells have been identified as playing a key role in pancreatic cancer desmoplasia. There is accumulating evidence that the stroma contributes to tumour progression and to the low therapeutic response of PDAC patients. In this review we described the main actors of the desmoplastic reaction within PDAC and novel therapeutic approaches that are being tested to block the detrimental function of the stroma.

Circulating IL-35 in pancreatic ductal adenocarcinoma patients

IL-35 is a novel inhibitory cytokine that is mainly produced by regulatory T-cells (Tregs) and is required for Treg-mediated immunosuppression. However, the plasma levels of IL-35 in patients with pancreatic ductal adenocarcinoma (PDAC) have never been investigated. In this study, we found that plasma IL-35 levels more significantly increased in PDAC patients than in normal controls (134.53 ± 92.45 pg/mL vs. 14.26 ± 6.56 pg/mL). IL-35 mRNA levels were positively correlated with plasma IL-35 levels (EBI3, R = 0.925, p<0.01; p35, R = 0.916, p<0.01). Furthermore, IL-35 expression levels were associated with lymph node metastasis (p = 0.001) and late tumor stage (p = 0.002). For the resected patients, high IL-35 expression levels were associated with large tumor size (p<0.01), higher TNM classification T staging (p<0.05), and late tumor stage (p<0.05). In conclusion, circulating IL-35 in PDAC patients significantly increased, suggesting that regulating the expression of IL-35 may provide a new possible target for the treatment of PDAC patients, especially for the resectable ones.

REG3β contributes to the immunosuppressive microenvironment of pancreatic cancer

The levels of regenerating islet-derived 3β (REG3β) in the serum and pancreatic juice of patients affected by pancreatic ductal adenocarcinomas are increased. However, whether such an elevation is relevant to oncogenesis and tumor progression has not yet been carefully examined. We have recently demonstrated that silencing REG3β in a pancreatic cancer model impairs tumor growth by skewing macrophage polarization.

Autophagy in tumour cell death

In every moment of a cell's existence one key question is always asked, "To be or not to be"? Cells constantly weigh up signals from their environment against their own integrity and metabolic status and decide whether to live or die. Such cell death decisions are central to the progression and treatment of cancer. The term autophagy describes three processes that deliver cytoplasmic macromolecules and organelles to lysosomes for degradation, the difference between each form being the method of delivery. The most extensively studied form is macroautophagy (hereafter referred to as autophagy) where cytosolic components are engulfed by double membraned autophagosomes. Autophagosomes fuse with lysosomes to form structures called autolysosomes, within which organelles, proteins and other macromolecules are degraded by catabolic enzymes in the acidic lysosome environment. Autophagy, which normally occurs at low levels in unstressed cells, is widely regarded as having a positive effect on cell health as potentially harmful protein aggregates and damaged organelles can be recycled. During periods of nutrient shortage autophagy is enhanced to provide, albeit temporarily, an internal energy source. Autophagy is also enhanced by other stresses encountered by tumour cells and this may protect the cell or aid its demise. In this review we examine the effect of autophagy on cell death decisions in tumour cells.

Detection of pancreatic ductal adenocarcinoma in mice by ultrasound imaging of thymocyte differentiation antigen 1

BACKGROUND & AIMS

Early detection of pancreatic ductal adenocarcinoma (PDAC) allows for surgical resection and increases patient survival times. Imaging agents that bind and amplify the signal of neovascular proteins in neoplasms can be detected by ultrasound, enabling accurate detection of small lesions. We searched for new markers of neovasculature in PDAC and assessed their potential for tumor detection by ultrasound molecular imaging.

METHODS

Thymocyte differentiation antigen 1 (Thy1) was identified as a specific biomarker of PDAC neovasculature by proteomic analysis. Up-regulation in PDAC was validated by immunohistochemical analysis of pancreatic tissue samples from 28 healthy individuals, 15 with primary chronic pancreatitis tissues, and 196 with PDAC. Binding of Thy1-targeted contrast microbubbles was assessed in cultured cells, in mice with orthotopic PDAC xenograft tumors expressing human Thy1 on the neovasculature, and on the neovasculature of a genetic mouse model of PDAC.

RESULTS

Based on immunohistochemical analyses, levels of Thy1 were significantly higher in the vascular of human PDAC than chronic pancreatitis (P = .007) or normal tissue samples (P < .0001). In mice, ultrasound imaging accurately detected human Thy1-positive PDAC xenografts, as well as PDACs that express endogenous Thy1 in genetic mouse models of PDAC.

CONCLUSIONS

We have identified and validated Thy1 as a marker of PDAC that can be detected by ultrasound molecular imaging in mice. The development of a specific imaging agent and identification of Thy1 as a new biomarker could aid in the diagnosis of this cancer and management of patients.

Emerging targets in pancreatic cancer: epithelial-mesenchymal transition and cancer stem cells

Pancreatic ductal adenocarcinoma is one of the most aggressive solid malignancies and is characterized by poor response to current therapy and a dismal survival rate. Recent insights regarding the role of cancer stem cells (CSCs) and epithelial–mesenchymal transition (EMT) in tumorigenesis have brought further understanding to the field and have highlighted new therapeutic targets. CSCs are a distinct subset of cancer cells, with the ability to differentiate into other cell types and self-renew in order to fuel the maintenance of tumor amplification. Transition of a cancer cell from an EMT leads to increased migratory and invasive properties, and thus facilitates initiation of metastasis. EMT is regulated by a complex network of factors that includes cytokines, growth factors, aberrant signaling pathways, transcription factors, and the tumor microenvironment. There is emerging evidence that the EMT process may give rise to CSCs, or at least cells with stem cell-like properties. We review the key pathways involved in both of these processes, the biomarkers used to identify CSCs, and new therapeutic approaches targeting CSCs and EMT in pancreatic ductal adenocarcinoma.

Trisomy of the Dscr1 gene suppresses early progression of pancreatic intraepithelial neoplasia driven by oncogenic Kras

Individuals with Down syndrome exhibit remarkably reduced incidence of most solid tumors including pancreatic cancer. Multiple mechanisms arising from the genetic complexity underlying Down syndrome has been suggested to contribute to such a broad cancer protection. In this study, utilizing a genetically engineered mouse model of pancreatic cancer, we demonstrate that trisomy of the Down syndrome critical region-1 (Dscr1), an endogenous calcineurin inhibitor localized on chromosome 21, suppresses the progression of pancreatic intraepithelial neoplasia-1A (PanIN-1A) to PanIN-1B lesions without affecting the initiation of PanIN lesions mediated by oncogenic Kras(G12D). In addition, we show that Dscr1 trisomy attenuates nuclear localization of nuclear factor of activated T-cells (NFAT) accompanied by upregulation of the p15(Ink4b) tumor suppressor and reduction of cell proliferation in early PanIN lesions. Our data suggest that attenuation of calcineurin-NFAT signaling in neoplastic pancreatic ductal epithelium by a single extra copy of Dscr1 is sufficient to inhibit the progression of early PanIN lesions driven by oncogenic Kras, and thus may be a potential mechanism underlying reduced incidence of pancreatic cancer in Down syndrome individuals.

Assessment of the stromal contribution to Sonic Hedgehog-dependent pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies. It is typically detected at an advanced stage, at which the therapeutic options are very limited. One remarkable feature of PDAC that contributes to its resilience to treatment is the extreme stromal activation seen in these tumors. Often, the vast majority of tumor bulk consists of non-tumor cells that together provide a tumor-promoting environment. One of the signals that maintains and activates the stroma is the developmental protein Sonic Hedgehog (SHH). As the disease progresses, tumor cells produce increasing amounts of SHH, which activates the surrounding stroma to aid in tumor progression. To better understand this response and identify targets for inhibition, we aimed to elucidate the proteins that mediate the SHH-driven stromal response in PDAC. For this a novel mixed-species coculture model was set up in which the cancer cells are human, and the stroma is modeled by mouse fibroblasts. In conjunction with next-generation sequencing we were able to use the sequence difference between these species to genetically distinguish between the epithelial and stromal responses to SHH. The stromal SHH-dependent genes from this analysis were validated and their relevance for human disease was subsequently determined in two independent patient cohorts. In non-microdissected tissue from PDAC patients, in which a large amount of stroma is present, the targets were confirmed to associate with tumor stroma versus normal pancreatic tissue. Patient survival analysis and immunohistochemistry identified CDA, EDIL3, ITGB4, PLAUR and SPOCK1 as SHH-dependent stromal factors that are associated with poor prognosis in PDAC patients. Summarizing, the presented data provide insight into the role of the activated stroma in PDAC, and how SHH acts to mediate this response. In addition, the study has yielded several candidates that are interesting therapeutic targets for a disease for which treatment options are still inadequate.

MicroRNAs as diagnostic markers for pancreatic ductal adenocarcinoma and its precursor, pancreatic intraepithelial neoplasm

Since the discovery of small non-coding RNAs, the analysis of microRNA (miRNA) expression patterns in human cancer have provided new insights into cancer biology. Evidence suggests that deregulated miRNA expression is associated with pancreatic cancer development. In this study, we analyzed the expression of several miRNAs in different types of pancreatic disease to determine if miRNA expression could aid in the diagnosis of pancreatic ductal adenocarcinoma (PDAC) and its precursor, pancreatic intraepithelial neoplasm (PanIN). Pancreatic resection specimens were selected, which included PDAC (n = 16), benign pancreatic parenchyma from corresponding carcinoma cases (n = 16), chronic pancreatitis (n = 4), normal pancreatic parenchyma (n = 5), and PanIN (n = 5). The expression levels of five miRNA (miR-148a, miR-217, miR-21, miR-196a, and miR-10b) were assessed by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) assays. Our data demonstrate that compared to the normal pancreatic parenchyma, miR-148a and miR-217 expression levels were down-regulated in PanIN, particularly in PanIN II-III and PDAC, whereas the level of miR-196 was significantly up-regulated in PDAC and its precursor, PanIN II-III. In addition, we observed that miR-21 was significantly overexpressed in PDAC, and miR-10b was highly expressed in PanIN II-III. Our study demonstrates that certain miRNAs, especially miR-148a, miR-217, and miR-196a, are significantly deregulated in PDAC, including in the early stage of PDAC. These markers can potentially be used as diagnostic markers to distinguish PDAC and its precursor from benign lesions.

Overcoming the stromal barrier for targeted delivery of HPMA copolymers to pancreatic tumors

Delivery of macromolecules to pancreatic cancer is inhibited by a dense extracellular matrix composed of hyaluronic acid, smooth muscle actin and collagen fibers. Hyaluronic acid causes a high intratumoral fluidic pressure which prevents diffusion and penetration into the pancreatic tumor. This study involves the breaking down of hyaluronic acid by treating CAPAN-1 xenograft tumors in athymic nu/nu mice with targeted N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers radiolabeled with (111)In for single photon emission computerized tomography (SPECT) imaging. Two targeting strategies were investigated including αvβ3 integrin and HER2 receptors. HPMA copolymers were targeted to these receptors by conjugating short peptide ligands cRGDfK and KCCYSL to the side chains of the copolymer. Results demonstrate that tumor targeting can be achieved in vivo after treatment with hyaluronidase. This approach shows promise for enhanced delivery of polymer-peptide conjugates to solid tumors.

Alternatively spliced tissue factor contributes to tumor spread and activation of coagulation in pancreatic ductal adenocarcinoma

Alternatively spliced tissue factor (asTF) promotes neovascularization and monocyte recruitment via integrin ligation. While asTF mRNA has been detected in some pancreatic ductal adenocarcinoma (PDAC) cell lines and increased asTF expression can promote PDAC growth in a subcutaneous model, the expression of asTF protein in bona fide PDAC lesions and/or its role in metastatic spread are yet to be ascertained. We here report that asTF protein is abundant in lesional and stromal compartments of the five studied types of carcinoma including PDAC. Analysis of 29 specimens of PDAC revealed detectable asTF in >90% of the lesions with a range of staining intensities. asTF levels in PDAC lesions positively correlated with the degree of monocyte infiltration. In an orthotopic model, asTF-overexpressing high-grade PDAC cell line Pt45P1/asTF+ produced metastases to distal lymph nodes, which stained positive for asTF. PDAC cells stimulated with and/or overexpressing asTF exhibited upregulation of genes implicated in PDAC progression and metastatic spread. Pt45P1/asTF+ cells displayed higher coagulant activity compared to Pt45P1 cells; the same effect was observed for cell-derived microparticles (MPs). Our findings demonstrate that asTF is expressed in PDAC and lymph node metastases and potentiates PDAC spread in vivo. asTF elicits global changes in gene expression likely involved in tumor progression and metastatic dissemination, and it also enhances the procoagulant potential of PDAC cells and cell-derived MPs. Thus, asTF may comprise a novel therapeutic target to treat PDAC and, possibly, its thrombotic complications.

The biological features of PanIN initiated from oncogenic Kras mutation in genetically engineered mouse models

Pancreatic intraepithelial neoplasia (PanIN) is the most common premalignant lesion of the pancreas. Further understanding of the biological behavior and molecular genetic alterations in the stepwise progression of PanINs is necessary toward the development of pancreatic ductal adenocarcinoma (PDAC) interventions. In this study, we analyzed the morphological characteristics, molecular alterations, and biological behavior of pancreatic wild-type and neoplasia tissues, including analysis of PanIN cell line SH-PAN (isolated from Pdx-1-Cre; LSL-KrasG12D/+ mouse) and PDAC cell line DT-PCa (isolated from Pdx1-Cre; LSL-KrasG12D/+; LSL-Tp53R172H/+ mouse. Results show that KrasG12D induces ductal lesion PanINs. Increased expression of EGFR, Her-2/Neu, p-MAPK and β-Catenin was observed in low-grade PanINs. Tp53 was not expressed in wild-type and low-grade PanINs, however, increased expression was observed in high-grade PanINs. Furthermore, SH-PAN cells did not exhibit any colony formation and showed significantly lower migration and invasion ability compared with DT-PCa cells. Notably, we first found PPP2R2A (protein phosphatase 2, regulatory subunit B, alpha) expression was significantly higher in SH-PAN cells than DT-PCa cells, and was high in 96 of 172 peritumoral normal human pancreatic tissues and 20 of 36 human low- or middle-grade PanIN tissues, whereas, was weak or negligible in 12 of 20 human high-grade PanIN tissues and 124 of 172 human PDAC tissues post-operation. The expression of PPP2R2A appears to be correlated with clinical survival. Taken together, Kras(G12D) - driven PanIN showed the tumorigenic ability, however, did not undergo a malignant transformation, and decreased expression of PPP2R2A in PDACs may provided a new target for pancreatic carcinoma intervention.

RABL6A Promotes Oxaliplatin Resistance in Tumor Cells and Is a New Marker of Survival for Resected Pancreatic Ductal Adenocarcinoma Patients

Pancreatic ductal adenocarcinoma (PDAC) is characterized by early recurrence following pancreatectomy, rapid progression, and chemoresistance. Novel prognostic and predictive biomarkers are urgently needed to both stratify patients for clinical trials and select patients for adjuvant therapy regimens. This study sought to determine the biological significance of RABL6A (RAB, member RAS oncogene family-like protein 6 isoform A), a novel pancreatic protein, in PDAC. Analyses of RABL6A protein expression in PDAC specimens from 73 patients who underwent pancreatic resection showed that RABL6A levels are altered in 74% of tumors relative to adjacent benign ductal epithelium. Undetectable RABL6A expression, found in 7% (5/73) of patients, correlated with improved overall survival (range 41 to 118 months with 3/5 patients still living), while patients with RABL6A expression had a worse outcome (range 3.3 to 100 months, median survival 20.3 months) (P = 0.0134). In agreement with those findings, RABL6A expression was increased in pancreatic cancer cell lines compared to normal pancreatic epithelial cells, and its knockdown inhibited pancreatic cancer cell proliferation and induced apoptosis. Moreover, RABL6A depletion selectively sensitized cells to oxaliplatin-induced arrest and death. This work reveals that RABL6A promotes the proliferation, survival, and oxaliplatin resistance of PDAC cells, whereas its loss is associated with extended survival in patients with resected PDAC. Such data suggest RABL6A is a novel biomarker of PDAC and potential target for anticancer therapy.

Metformin inhibits the growth of human pancreatic cancer xenografts

OBJECTIVE

Pancreatic ductal adenocarcinoma is a devastating disease, with an overall 5-year survival rate of only 3% to 5%. As the current therapies offer very limited survival benefits, novel therapeutic strategies are urgently required to treat this disease. Here, we determined whether metformin administration inhibits the growth of PANC-1 and MiaPaCa-2 tumor xenografts in vivo.

METHODS

Different xenograft models, including orthotopic implantation, were used to determine whether intraperitoneal or oral administration of metformin inhibits the growth of pancreatic cancer in vivo.

RESULTS

We demonstrate that metformin given once daily intraperitoneally at various doses (50-250 mg/kg) to nude mice inhibited the growth of PANC-1 xenografts in a dose-dependent manner. A significant effect of metformin was obtained at 50 mg/kg and maximal effect at 200 mg/kg. Metformin administration also caused a significant reduction in the phosphorylation of ribosomal S6 protein and ERK in these xenografts. Metformin also inhibited the growth of pancreatic cancer xenografts when administered orally (2.5 mg/mL) either before or after tumor implantation. Importantly, oral administration of metformin also inhibited the growth of MiaPaCa-2 tumors xenografted orthotopically.

CONCLUSIONS

The studies presented here provide further evidence indicating that metformin offers a potential novel approach for pancreatic ductal adenocarcinoma prevention and therapy.

Meta-analysis of microRNA-183 family expression in human cancer studies comparing cancer tissues with noncancerous tissues

MicroRNA-183 (miR-183) family is proposed as promising biomarkers for early cancer detection and accurate prognosis as well as targets for more efficient treatment. The results of their expression feature in cancer tissues are inconsistent and controversy still exists in identifying them as new biomarkers of cancers. Therefore, to systemically evaluate the most frequently reported cancers in which miR-183 family members were up- or down-regulated is critical for further investigation on physiological impact of its aberrant regulation in specific cancers. The published studies that compared the level of miR-183 family expression in cancer tissues with those in noncancerous tissues were reviewed by the meta-analysis with a vote-counting strategy. Among the 49 included studies, a total of 18 cancers were reported, with 11 cancers reported in at least two studies. In the panel of miR-183 family members' expression analysis, colorectal cancer and prostate cancer ranked at the top among consistently reported cancer types with up-regulated feature. Bladder cancer, lung cancer and hepatocellular carcinoma were the third most frequently reported cancer types with significant over-expression of miR-96, miR-182 and miR-183 respectively. Breast cancer and gastric cancer were presented with inconsistent regulations and the members of this family had their own distinct regulated features in other different cancers. MiR-183 family, either individually or as a cluster, may be useful prognostic markers and/or therapeutic targets in several cancers. Further studies and repeat efforts are still required to determine the role of miR-183 family in various cancer progressions.

Network insights into the genes regulated by hepatocyte nuclear factor 4 in response to drug induced perturbations: a review

Transcription factors (TFs) play central role in normal cellular physiology and their aberrant expression is linked to different diseases. Hepatocyte Nuclear Factors (HNFs) are TFs that have been recognized to play multiple roles in liver physiology. Emerging research has highlighted their function in the sustenance of solid tumors, indicating that HNFs could serve as possible therapeutic targets in cancer. Although, there have been many attempts to develop HNF targeted drugs, the myriad downstream targets associated with these transcription factors, some of which are critical for normal cell homeostasis, led to the realization that HNFs are not easily druggable. Therefore, identifying and optimizing drugs that can selectively inactivate HNFs is a challenge to the pharmaceutical industry. To achieve this, a more in-depth understanding is required of the HNFs binding partners, the protein interaction networks it regulates and the resulting phenotype. This calls for network analysis of the pathways regulated by HNFs and how chemical perturbations can selectively activate or suppress their functions. Network biology is an emerging field of research that is finding applications in cancer drug discovery. Specifically, network pharmacology is cementing its position in cancer research and has various applications such as biomarker identification, in determining synergistic drug pairs and in drug repurposing. Developing a network understanding of HNFs, the target it hits and responses thereof can enhance our ability to design drugs against these TFs. This article reviews how network pharmacology can help in the identification of druggable avenues in TFs and also allow the selection of drugs and their synergistic pairs against HNFs for cancer therapy.

Inflammation, autophagy, and obesity: common features in the pathogenesis of pancreatitis and pancreatic cancer

Inflammation and autophagy are cellular defense mechanisms. When these processes are deregulated (deficient or overactivated) they produce pathologic effects, such as oxidative stress, metabolic impairments, and cell death. Unresolved inflammation and disrupted regulation of autophagy are common features of pancreatitis and pancreatic cancer. Furthermore, obesity, a risk factor for pancreatitis and pancreatic cancer, promotes inflammation and inhibits or deregulates autophagy, creating an environment that facilitates the induction and progression of pancreatic diseases. However, little is known about how inflammation, autophagy, and obesity interact to promote exocrine pancreatic disorders. We review the roles of inflammation and autophagy, and their deregulation by obesity, in pancreatic diseases. We discuss the connections among disordered pathways and important areas for future research.

Role of immune cells and immune-based therapies in pancreatitis and pancreatic ductal adenocarcinoma

Immune cells are important in the pathogenesis of acute pancreatitis and determine disease severity. Results from cytokine-based clinical trials for acute pancreatitis have been disappointing, so strategies that target and alter the behavior of infiltrating immune cells require consideration. Recurrent acute pancreatitis can progress to chronic pancreatitis, which is a well-described risk factor for pancreatic ductal adenocarcinoma (PDA). However, most patients with chronic pancreatitis do not develop PDA, and most patients with PDA do not have a history of pancreatitis. Interestingly, chronic pancreatitis and PDA tissues have similarities in their desmoplasia and inflammatory infiltrates, indicating overlapping inflammatory responses. Further studies are needed to determine the differences and similarities of these responses, improve our understanding of PDA pathogenesis, and develop specific immune-based therapies. Immune cells in PDA produce immunosuppressive signals that allow tumors to evade the immune response. Unlike single therapeutic agent studies that block immunosuppressive mechanisms, studies of combination therapies that include therapeutic vaccines have provided promising results.

The S100A8/A9 complex reduces CTLA4 expression by immature myeloid cells: Implications for pancreatic cancer-driven immunosuppression

An expansion of different myeloid derived suppressive cell (MDSC) subsets can be detected in the blood and secondary lymphoid organs of early and advanced pancreatic ductal adenocarcinoma (PDAC) patients. Double negative (CD14⁻HLA-DR⁻) MDSCs are frequently induced by PDACs. In addition, by releasing S100A8 and S100A9, advanced PDAC lesions cause an expansion of highly immunosuppressive CD33⁺CD14⁺HLA-DR⁻ monocytic MDSCs expressing low levels of cytotoxic T lymphocyte antigen 4 (CTLA4) on the cell surface.

The effect of gadolinium chelate contrast agent on diffusion-weighted imaging of pancreatic ductal adenocarcinoma

BACKGROUND

There are only two studies that discuss the effect of a gadolinium chelate contrast agent on pancreatic diffusion-weighted imaging (DWI). However, both studies only included normal pancreas and/or pancreas with pancreatitis and did not include pancreatic ductal adenocarcinoma (PDA).

PURPOSE

To investigate the effect of gadolinium chelate contrast agent on DWI of PDA.

MATERIAL AND METHODS

Twenty-two patients (13 men, 9 women; mean age 62 years) with histopathologically proven PDA were included in this study. DWI was acquired before and after administration of gadopentetate dimeglumine (Magnevist) with two b-values: 0 and 1000 s/mm(2). The signal intensity (SI), signal-to-noise ratio (SNR), and the apparent diffusion coefficient (ADC) of the lesion were recorded for comparison.

RESULTS

The mean time interval between the initiation of contrast administration and the start of the postcontrast DWI series was 393 s (range, 350-510 s). The SIs and SNRs of lesions of b1000 and b0 images of enhanced images were significantly higher than non-enhanced images (P < 0.001, P < 0.001 for b1000 s/mm(2); P = 0.001, P = 0.001 for b0 s/mm(2)). The ADC of all PDAs revealed no statistically significant difference between non-enhanced and enhanced images (P = 0.709). There was also no significant difference between non-enhanced and enhanced images in subgroups based on grades of differentiation and locations of lesion.

CONCLUSION

With increasing SI and SNR of PDA, intravenous contrast administration does not result in a significant difference in quantitative ADC measurements when comparing precontrast to postcontrast DWI when acquired approximately 6-7 min after administration.

Effect of CCR7, CXCR4 and VEGF-C on the lymph node metastasis of human pancreatic ductal adenocarcinoma

The aim of the present study was to investigate the association between the expression of chemokine receptors CCR7 and CXCR4 and vascular endothelial growth factor (VEGF)-C and the lymph node metastasis of pancreatic ductal adenocarcinoma (PDAC). The mRNA transcription levels of CCR7, CXCR4 and VEGF-C were measured in 24 specimens by real-time reverse transcription (RT)-PCR, while the protein expression levels were measured in 65 specimens by immuohistochemistry. Professional software for pathological image manipulation (Image Pro Plus 6.0) was used to quantitate the results of the immunohistochemical staining. The mRNA and protein expression levels of CCR7, CXCR4 and VEGF-C were all significantly higher in the cancer samples compared with those in the adjacent normal tissue. The CCR7 and VEGF-C mRNA and protein expression levels were significantly higher in the patients with cancer types exhibiting lymph node metastasis and an advanced International Union Against Cancer (UICC) stage (P<0.05). The greater the number of metastatic lymph nodes, the higher the levels of CCR7 expression (P<0.05). There was a significant positive linear correlation between the mRNA and protein expression levels of CCR7 and VEGF-C (P<0.05). The mRNA and protein expression levels of CXCR4 were not correlated with the lymph node metastasis (P>0.05), however the strong positive expression of CCR7 and VEGF-C was significantly associated with the lymph node metastasis of PDAC.

Preoperative CEA and CA 19-9 are prognostic markers for survival after curative resection for ductal adenocarcinoma of the pancreas - a retrospective tumor marker prognostic study

BACKGROUND

The prognosis for patients with ductal adenocarcinoma of the pancreas (PDAC) remains poor even after curative resection. Carbohydrate antigen 19-9 (CA 19-9) and the carcinoembryonic antigen (CEA) are the most widely used serum-based tumor markers for the diagnosis and follow up of pancreatic cancer. In our analysis we aim to assess the prognostic value of a combination of both tumor markers in patients with pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

Between 01/1995 and 08/2012 we performed a total of 264 pancreatic resections due to PDAC. Patients were stratified into 3 groups in regard to their preoperative tumor marker levels. Survival was compared between the groups using Kaplan Meier analysis and log rank test. Univariate subgroup analysis and multivariate analysis were performed.

RESULTS

For 259 cases complete follow up could be obtained. In patients with low preoperative CEA and CA 19-9 levels (group 1 n = 91) the mean survival was 33.3 month (CI 95% 25.1-41.5). If one of the analyzed tumor markers (CEA/CA19-9) was preoperatively elevated above the cut-off level (group 2 n = 106) mean survival was 28.5 month (CI 95% 22.1-35.1). 62 patients showed preoperative elevation of both, CEA and CA 19-9 (group 3); mean survival in this group was 23.9 month (CI 95% 13.9-33.9), p > 0.01. Multivariate analysis confirmed preoperative CEA/CA 19-9 level as independent prognostic factor (HR 1.299).

CONCLUSION

Preoperative CEA and CA 19-9 levels correlate with patient prognosis after curative pancreatic resection due to PDAC. This is especially true for the most frequently pT 3/4 stages of PDAC. Even if CEA and CA 19-9 might not be appropriate for screening, its serum levels should therefore be determined prior to operation and taken into account when resectability or operability is doubtful.

Pancreatic cancer circulating tumour cells express a cell motility gene signature that predicts survival after surgery

BACKGROUND

Most cancer deaths are caused by metastases, resulting from circulating tumor cells (CTC) that detach from the primary cancer and survive in distant organs. The aim of the present study was to develop a CTC gene signature and to assess its prognostic relevance after surgery for pancreatic ductal adenocarcinoma (PDAC).

METHODS

Negative depletion fluorescence activated cell sorting (FACS) was developed and validated with spiking experiments using cancer cell lines in whole human blood samples. This FACS-based method was used to enrich for CTC from the blood of 10 patients who underwent surgery for PDAC. Total RNA was isolated from 4 subgroup samples, i.e. CTC, haematological cells (G), original tumour (T), and non-tumoural pancreatic control tissue (P). After RNA quality control, samples of 6 patients were eligible for further analysis. Whole genome microarray analysis was performed after double linear amplification of RNA. 'Ingenuity Pathway Analysis' software and AmiGO were used for functional data analyses. A CTC gene signature was developed and validated with the nCounter system on expression data of 78 primary PDAC using Cox regression analysis for disease-free (DFS) and overall survival (OS).

RESULTS

Using stringent statistical analysis, we retained 8,152 genes to compare expression profiles of CTC vs. other subgroups, and found 1,059 genes to be differentially expressed. The pathway with the highest expression ratio in CTC was p38 mitogen-activated protein kinase (p38 MAPK) signaling, known to be involved in cancer cell migration. In the p38 MAPK pathway, TGF-β1, cPLA2, and MAX were significantly upregulated. In addition, 9 other genes associated with both p38 MAPK signaling and cell motility were overexpressed in CTC. High co-expression of TGF-β1 and our cell motility panel (≥ 4 out of 9 genes for DFS and ≥ 6 out of 9 genes for OS) in primary PDAC was identified as an independent predictor of DFS (p=0.041, HR (95% CI) = 1.885 (1.025 - 3.559)) and OS (p=0.047, HR (95% CI) = 1.366 (1.004 - 1.861)).

CONCLUSIONS

Pancreatic CTC isolated from blood samples using FACS-based negative depletion, express a cell motility gene signature. Expression of this newly defined cell motility gene signature in the primary tumour can predict survival of patients undergoing surgical resection for pancreatic cancer.

TRIAL REGISTRATION

Clinical trials.gov NCT00495924.

MSX2 in pancreatic tumor development and its clinical application for the diagnosis of pancreatic ductal adenocarcinoma

MSX2, a member of the homeobox genes family, is demonstrated to be the downstream target for ras signaling pathway and is expressed in a variety of carcinoma cells, suggesting its relevance to the development of ductal pancreatic tumors since pancreatic ductal adenocarcinoma (PDAC) and intraductal papillary-mucinous neoplasia (IPMN) harbor frequent K-ras gene mutations. Recent studies revealed the roles of MSX2 in the development of carcinoma of various origins including pancreas. Among gastrointestinal tumors, PDAC is one of the most malignant. PDAC progresses rapidly to develop metastatic lesions, frequently by the time of diagnosis, and these tumors are usually resistant to conventional chemotherapy and radiation therapy. The molecular mechanisms regulating the aggressive behavior of PDAC still remain to be clarified. On the other hand, IPMN of the pancreas is distinct from PDAC because of its intraductal growth in the main pancreatic duct or secondary branches with rare invasion and metastasis to distant organs. However, recent evidence indicated that once IPMN showed stromal invasion, it progresses like PDAC. Therefore, it is important to determin how IPMN progresses to malignant phenotype. In this review, we focus on the involvement of MSX2 in the enhancement of malignant behavior in PDAC and IPMN, and further highlight the clinical approach to differentiate PDAC from chronic pancreatitis by evaluating MSX2 expression level.

Selective reoperation for locally recurrent or metastatic pancreatic ductal adenocarcinoma following primary pancreatic resection

BACKGROUND

Resection of certain recurrent malignancies can prolong survival, but resection of recurrent pancreatic ductal adenocarcinoma is typically contraindicated because of poor outcomes.

METHODS

All patients from 1992 to 2010 with recurrent pancreatic cancer after intended surgical cure were retrospectively evaluated. Clinicopathologic features were compared from patients who did and did not undergo subsequent reoperation with curative intent to identify factors associated with prolonged survival.

RESULTS

Twenty-one of 426 patients (5 %) with recurrent pancreatic cancer underwent potentially curative reoperation for solitary local-regional (n = 7) or distant (n = 14) recurrence. The median disease-free interval after initial resection among reoperative patients was longer for those with lung or local-regional recurrence (52.4 and 41.1 months, respectively) than for those with liver recurrence (7.6 months, p = 0.006). The median interval between reoperation and second recurrence was longer in patients with lung recurrence (median not reached) than with liver or local-regional recurrence (6 and 9 months, respectively, p = 0.023). Reoperative patients with an initial disease-free interval >20 months had a longer median survival than those who did not (92.3 versus 31.3 months, respectively; p = 0.033).

CONCLUSION

Patients with a solitary pulmonary recurrence of pancreatic cancer after a prolonged disease-free interval should be considered for reoperation, as they are more likely to benefit from resection versus other sites of solitary recurrence.

Obesity, autophagy and the pathogenesis of liver and pancreatic cancers

Liver and pancreatic cancers are both highly lethal diseases with limited to no therapeutic options for patients. Recent studies suggest that deregulated autophagy plays a role in the pathogenesis of these diseases by perturbing cellular homeostasis and laying the foundation for disease development. While accumulation of p62 upon impaired autophagy has been implicated in hepatocellular carcinoma, its role in pancreatic ductal adenocarcinoma remains less clear. This review will focus on recent studies illustrating the role of autophagy in liver and pancreatic cancers. The relationships between autophagy, nuclear factor-κB signaling and obesity in hepatocellular carcinoma will be discussed, as well as the dual role of autophagy in pancreatic ductal adenocarcinoma.

The novel triad of dorsal agenesis of the pancreas with concurrent pancreatic ductal adenocarcinoma and nonalcoholic chronic calcific pancreatitis: a case series and review of the literature

INTRODUCTION

Dorsal agenesis of the pancreas (DAP) is a rare congenital anomaly, with only 44 cases having been reported in the English literature since 1966.

MATERIALS AND METHODS

A retrospective review of our IRB-approved pancreatic surgery database was performed from November 2005 to November 2010 searching for cases of DAP.

DISCUSSION

Disorders in the retinoic acid (Raldh) and hedgehog (Hh) signaling pathways, which appear to play a role in the development of DAP, have been implicated in other diseases of the pancreas such as pancreatic ductal adenocarcinoma (PDA) and nonalcoholic chronic calcific pancreatitis (NCCP).

CONCLUSION

In this report, we describe three cases of DAP in the setting of PDA, two of which include the third component of NCCP. We provide a discussion of the clinical features of this novel triad and address the molecular pathways that relate to these respective diseases.

Aberrant expressions of AP-2α splice variants in pancreatic cancer

OBJECTIVES

The present study was conducted to evaluate the expression and function of AP-2α isoforms in pancreatic ductal adenocarcinoma.

METHODS

The expression of AP-2α was evaluated at the RNA level by reverse transcription-polymerase chain reaction and at the protein level by Western blotting and immunofluorescence. Its function as a transcription factor was evaluated in transient transfection experiments: DNA binding properties by electromobility shift assay and transactivation capabilities by luciferase assay.

RESULTS

Multiple alternative splicing events of AP-2α messenger occurred in all human pancreatic cancer cell lines, including a novel isoform, termed variant 6, which was not present in HeLa cells. At the protein level, except for 1 cell line, all pancreatic cancer cell lines expressed high nuclear levels of AP-2α. We also showed that AP-2α expressed by the pancreatic cancer cell lines could bind its cognate recognition site and activate transcription. However, variant 6, although not able to activate transcription, did not act in a dominant negative manner when cotransfected with the full-length protein.

CONCLUSIONS

Multiple isoforms of AP-2α are highly expressed in pancreatic cancer cell lines including a new isoform, AP-2α variant 6, which seems to be pancreatic cancer specific and is deprived of transcriptional activity.

Down-regulation of Bax-interacting factor 1 in human pancreatic ductal adenocarcinoma

OBJECTIVE

Bax-interacting factor 1 (Bif-1) protein plays a critical role in apoptosis, mitochondrial morphogenesis, and autophagy, and its loss promotes tumorigenesis. The role of Bif-1 in pancreatic cancer has not been studied.

METHODS

We determined Bif-1 expression in 82 human pancreatic ductal adenocarcinomas (PDCs) and in 82 nonmalignant pancreatic specimens (NMPs), using immunohistochemistry and tissue microarray. Bif-1 immunostain was semiquantitatively scored on a scale of 0 to 9.

RESULTS

Bif-1 scores in NMP were either 6 or 9, with lower scores in only 19 (23.2%) of 82 NMPs. Low Bif-1 expression (score <6) was found in 37 (45.1%) of 82 PDCs, a proportion significantly greater than that found in NMP (P = 0.005). The expression of Bif-1 was twice as likely to be low in PDC as in NMP (relative risk = 1.95, 95% confidence interval, 1.23-3.09). Kaplan-Meier survival estimates showed no difference in survival between patients with low and high Bif-1 expression (P = 0.21, log-rank test).

CONCLUSIONS

The expression of Bif-1 is downregulated in a subset of PDC. This novel finding is in agreement with the tumor suppressor function of Bif-1. The lack of association between Bif-1 expression and patient survival may be best explained by the complexity of carcinogenesis.

Ductal adenocarcinoma of the pancreas: Expression of growth factor receptors, oncogenes and suppressor genes, and their relationship to pathological features, staging and survival

Pancreatic ductal adenocarcinoma results in high short-term mortality despite recent advances in diagnostics, surgery and chemotherapy. Modern chemotherapeutic agents directed to specific tumor receptors have higher therapeutic efficacy and lower adverse effects. However, few studies exist that evaluate the clinical impact in pancreatic cancer. The expression of tumor growth factor receptors, oncogenes and tumor suppressor oncogenes in surgical pancreatic cancer specimens as related to pathological characteristics, staging and prognosis was evaluated. Data were recorded for 50 patients who underwent a pancreatic cancer resection and were suitable for immunohistochemical evaluation (32 male, mean age 61 years, range 44-78) with regard to pTN, tumor size and location, histological differentiation grade, vascular and perineural invasion, adjuvant chemotherapy and survival time. Tumor specimens and normal pancreatic tissue were deparaffinized and the expression of vascular epidermal growth factor (VEGF) receptors (R)-1 and -2, epidermal growth factor receptor (EGFR), Her-2/neu, COX-2, p16, p21 and p53 was immunohistochemically evaluated using tissue microarrays. Associations between molecular marker expression and clinicopathological tumor characteristics were evaluated using the Chi-square test (SPSS) and the survival time was defined. The Kaplan-Meier method was utilized to analyze survival curves, verified by the log-rank test. No molecular markers evaluated were expressed in normal tissue. Tumor expression data included VEGF-R1 (74%), EGFR (52%), Her-2/neu (7.84%), COX-2 (21.5%), p16 (29.4%), p21 (21.7%) and p53 (50%). Tumors expressing VEGF-R1, EGFR and/or p53 were larger (p<0.02), frequently poorly differentiated (p<0.05) and more frequently associated with perineural and lymph node invasion (p<0.05). Marker expression did not correlate with pathological tumor characteristics. The median post-surgery survival was 15 months; 60 and 27% patients survived to 12 and 24 months, respectively, with a longer survival time in patients receiving adjuvant chemotherapy (n=20) (median 36 vs. 15 months, p<0.02). Growth factor receptors, oncogenes and tumor suppressor genes were frequently expressed in pancreatic cancer tissue. VEGF-R1, EGFR and p53 expression were associated with poor tissue differentiation and perineural and lymph node infiltration. Only VEGF-R1 expression was associated with a longer survival time and a more favorable response to adjuvant chemotherapy.

Molecular targeted approaches for treatment of pancreatic cancer

Human pancreatic cancer remains a highly malignant disease with almost similar incidence and mortality despite extensive research. Many targeted therapies are under development. However, clinical investigation showed that single targeted therapies and most combined therapies were not able to improve the prognosis of this disease, even though some of these therapies had excellent anti-tumor effects in pre-clinical models. Cross-talk between cell proliferation signaling pathways may be an important phenomenon in pancreatic cancer, which may result in cancer cell survival even though some pathways are blocked by targeted therapy. Pancreatic cancer may possess different characteristics and targets in different stages of pathogenesis, maintenance and metastasis. Sensitivity to therapy may also vary for cancer cells at different stages. The unique pancreatic cancer structure with abundant stroma creates a tumor microenvironment with hypoxia and low blood perfusion rate, which prevents drug delivery to cancer cells. In this review, the most commonly investigated targeted therapies in pancreatic cancer treatment are discussed. However, how to combine these targeted therapies and/or combine them with chemotherapy to improve the survival rate of pancreatic cancer is still a challenge. Genomic and proteomic studies using pancreatic cancer samples obtained from either biopsy or surgery are recommended to individualize tumor characters and to perform drug sensitivity study in order to design a tailored therapy with minimal side effects. These studies may help to further investigate tumor pathogenesis, maintenance and metastasis to create cellular expression profiles at different stages. Integration of the information obtained needs to be performed from multiple levels and dimensions in order to develop a successful targeted therapy.

Does the mechanism of lymph node invasion affect survival in patients with pancreatic ductal adenocarcinoma?

BACKGROUND

Lymph node metastases are prognostically significant in pancreatic ductal adenocarcinoma. Little is known about the significance of direct lymph node invasion.

AIM

The aim of this study is to find out whether direct lymph node invasion has the same prognostic significance as regional nodal metastases.

METHODS

Retrospective review of patients resected between 1/1/1993 and 7/31/2008. "Direct" was defined as tumor extension into adjacent nodes, and "regional" was defined as metastases to peripancreatic nodes.

RESULTS

Overall, 517 patients underwent pancreatic resection for adenocarcinoma, of whom 89 had one positive node (direct 26, regional 63), and 79 had two positive nodes (direct 6, regional 68, both 5). Overall, survival of node-negative patients was improved compared to patients with positive nodes (N0 30.8 months vs. N1 16.4 months; p < 0.001). There was no survival difference for patients with direct vs. regional lymph node invasion (p = 0.67). Patients with one positive node had a better overall survival compared to patients with >/=2 positive nodes (22.3 and 15 months, respectively; p < 0.001). The lymph node ratio (+LN/total LN) was prognostically significant after Cox regression (p < 0.001).

CONCLUSIONS

Isolated direct invasion occurs in 20% of patients with one to two positive nodes. Node involvement by metastasis or by direct invasion are equally significant predictors of reduced survival. Both the number of positive nodes and the lymph node ratio are significant prognostic factors.

HMGA1 correlates with advanced tumor grade and decreased survival in pancreatic ductal adenocarcinoma

Although pancreatic ductal adenocarcinoma is a common and almost uniformly fatal cancer, little is known about the molecular events that lead to tumor progression. The high-mobility group A1 (HMGA1) protein is an architectural transcription factor that has been implicated in the pathogenesis and progression of diverse human cancers, including pancreatic ductal adenocarcinoma. In this study, we investigated HMGA1 expression in pancreatic ductal adenocarcinoma cell lines and surgically resected tumors to determine whether it could be a marker for more advanced disease. By real-time quantitative RT-PCR, we measured HMGA1a mRNA in cultured pancreatic ductal adenocarcinoma cell lines and found increased levels in all cancer cells compared with normal pancreatic tissue. To investigate HMGA1 in primary human tumors, we performed immunohistochemical analysis of 125 cases of pancreatic adenocarcinoma and 99 precursor lesions (PanIN 1-3). We found nuclear staining for HMGA1 in 98% of cases of pancreatic adenocarcinoma, but only 43% of cases of PanIN precursor lesions. Moreover, HMGA1 immunoreactivity correlates positively with decreased survival and advanced tumor and PanIN grade. These results suggest that HMGA1 promotes tumor progression in pancreatic ductal adenocarcinoma and could be a useful biomarker and rational therapeutic target in advanced disease.

A resource for analysis of microRNA expression and function in pancreatic ductal adenocarcinoma cells

MicroRNAs (miRNAs) are 21-24 nucleotide RNA molecules that regulate the translation and stability of target messenger RNAs. Abnormal miRNA expression is a common feature of diverse cancers. Several previous studies have classified miRNA expression in pancreatic ductal adenocarcinoma (PDAC), although no uniform pattern of miRNA dysregulation has emerged. To clarify these previous findings as well as to set the stage for detailed functional analyses, we performed global miRNA expression profiling of 21 human PDAC cell lines, the most extensive panel studied to date. Overall, 39 miRNAs were found to be dysregulated and have at least two-fold or greater differential expression in PDAC cell lines compared to control nontransformed pancreatic ductal cell lines. Several of these miRNAs show comparable dysregulation in first-passage patient derived xenografts. Initial functional analyses demonstrate that enforced expression of miRNAs derived from the miR-200 family and the miR-17-92 cluster, both of which are overexpressed in PDAC cell lines, enhances proliferation. In contrast, inhibition of the miR-200 family, the miR-17-92 cluster, or miR-191 diminishes anchorage independent growth. Consistent with a known role for the miR-200 family in negatively regulating an epithelial-to-mesenchymal transition (EMT), the abundance of these miRNAs correlated positively with E-cadherin expression and negatively with the EMT-associated transcription factor and established miR-200 target ZEB1. Finally, restituted expression of miR-34a, a miRNA whose expression is frequently lost in PDAC cell lines, abrogates growth, demonstrating that the anti-proliferative activity of this miRNA is operative in PDAC. These results, and the widespread availability of PDAC cell lines wherein the aforementioned data were generated, provide a valuable resource for the pancreatic cancer research community and will greatly facilitate functional studies essential for elucidating the consequences of miRNA dysregulation in pancreatic cancer.

Epithelial-mesenchymal transition markers in pancreatic ductal adenocarcinoma

OBJECTIVES

Expression of transcription factors that mediate epithelial-mesenchymal transition (EMT), such as Twist and Slug, is correlated with poor prognosis in many tumor types. Selected EMT markers were studied in a series of pancreatic ductal adenocarcinomas (PDAs) and benign pancreatic tissues to determine whether expression levels correlated with diagnosis, histologic grade, or patient outcome.

METHODS

Immunohistochemical stains for Twist, Slug, and N-cadherin were performed using a tissue microarray containing 68 PDAs and 38 samples of normal pancreas or chronic pancreatitis tissues.

RESULTS

Twist and Slug were identified in both the nucleus and cytoplasm of benign pancreatic ductal epithelium, chronic pancreatitis, and PDA. Compared with normal ductal epithelium, nuclear levels of Twist are decreased in PDA. None of the other EMT markers showed significant differences in staining indices among the diagnostic groups. There were no correlations between EMT marker expression and histologic grade. Epithelial-mesenchymal transition marker expression was not associated with N-cadherin expression, patient outcome, or duration of survival.

CONCLUSIONS

Decreased expression of nuclear Twist is observed in malignant pancreatic epithelium. However, use of Twist as a diagnostic marker is precluded because decreased expression is also seen in chronic pancreatitis. None of the markers studied were predictive of patient outcome.