The role of the DNA damage checkpoint pathway in intraductal papillary mucinous neoplasms of the pancreas

New avenues for the treatment of immunotherapy-resistant pancreatic cancer

Pancreatic cancer (PC) is characterized by its extremely aggressive nature and ranks 14th in the number of new cancer cases worldwide. However, due to its complexity, it ranks 7th in the list of the most lethal cancers worldwide. The pathogenesis of PC involves several complex processes, including familial genetic factors associated with risk factors such as obesity, diabetes mellitus, chronic pancreatitis, and smoking. Mutations in genes such as KRAS, TP53, and SMAD4 are linked to the appearance of malignant cells that generate pancreatic lesions and, consequently, cancer. In this context, some therapies are used for PC, one of which is immunotherapy, which is extremely promising in various other types of cancer but has shown little response in the treatment of PC due to various resistance mechanisms that contribute to a drop in immunotherapy efficiency. It is therefore clear that the tumor microenvironment (TME) has a huge impact on the resistance process, since cellular and non-cellular elements create an immunosuppressive environment, characterized by a dense desmoplastic stroma with cancer-associated fibroblasts, pancreatic stellate cells, extracellular matrix, and immunosuppressive cells. Linked to this are genetic mutations in TP53 and immunosuppressive factors that act on T cells, resulting in a shortage of CD8+ T cells and limited expression of activation markers such as interferon-gamma. In this way, finding new strategies that make it possible to manipulate resistance mechanisms is necessary. Thus, techniques such as the use of TME modulators that block receptors and stromal molecules that generate resistance, the use of genetic manipulation in specific regions, such as microRNAs, the modulation of extrinsic and intrinsic factors associated with T cells, and, above all, therapeutic models that combine these modulation techniques constitute the promising future of PC therapy. Thus, this study aims to elucidate the main mechanisms of resistance to immunotherapy in PC and new ways of manipulating this process, resulting in a more efficient therapy for cancer patients and, consequently, a reduction in the lethality of this aggressive cancer.

Diagnostic Role of F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Characterization of Intraductal Papillary Mucinous Neoplasms: An Updated Systematic Review and Meta-analysis

OBJECTIVES

The purpose of the current study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) or PET/computed tomography (CT) for characterization of intraductal papillary mucinous neoplasms (IPMN) through a systematic review and meta-analysis.

METHODS

The PubMed and Embase database were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT for characterization of IPMN.

RESULTS

Across 14 studies (752 patients), the pooled sensitivity for F-18 FDG PET or PET/CT was 0.84 (95% confidence interval [CI], 0.77-0.89) with heterogeneity (I2 = 55.5, P = 0.01) and a pooled specificity of 0.95 (95% CI, 0.88-0.98) with heterogeneity (I2 = 83.9, P < 0.001). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 17.4 (95% CI, 6.5-46.8) and negative likelihood ratio (LR-) of 0.17 (95% CI, 0.12-0.25). The pooled diagnostic odds ratio was 101 (95% CI, 31-327). Hierarchical summary receiver operating characteristic curve and indicates that the areas under the curve were 0.93 (95% CI, 0.90-0.95).

CONCLUSIONS

The current meta-analysis showed a high sensitivity, specificity, diagnostic odds ratio, and the LR scatter gram of F-18 FDG PET or PET/CT for determination of characteristics of IPMN.

Cytologic Analysis of Pancreatic Juice Increases Specificity of Detection of Malignant IPMN-A Systematic Review

BACKGROUND & AIMS

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas can progress to cancer. Biomarkers have been identified that were reported to increase the accuracy of identification of malignant lesions; we performed a systematic review of the accuracy of these markers.

METHODS

We performed a systematic review of published studies on biomarkers of malignant IPMNs by searching MEDLINE and Web of Science databases from January 2005 through December 2017. Our methods were developed based on the Meta-analysis Of Observational Studies in Epidemiology guidelines. Pooled sensitivity, specificity, receiver operating characteristic curves, and their respective areas under the curve (AUC) were calculated from groups of markers (cell-, protein-, or DNA-based) measured in samples collected before and after surgery. A hypothetical test model was developed to determine how to meaningfully amend the revised Fukuoka guidelines, focusing on increasing test specificity for patients with IPMNs that have worrisome features.

RESULTS

We collected data from 193 published studies, comprising 12,297 patients, that analyzed 7 preoperative and 21 postoperative markers of IPMNs. The 3 biomarkers that identified malignant IPMNs with the largest AUC values were pancreatic juice cytology (AUC, 0.84; sensitivity, 0.54; specificity, 0.91), serum protein carbohydrate antigen 19-9 (AUC, 0.81; sensitivity, 0.45; specificity, 0.90), and cyst fluid cytology (AUC, 0.82; sensitivity, 0.57; specificity, 0.84). A combination of cytologic and immunohistochemical analysis of MUC1 and MUC2 in pancreatic juice samples identified malignant IPMNs with the largest AUC and sensitivity values (AUC, 0.85; sensitivity, 0.85; specificity, 0.65). In a test model, inclusion of cytologic analysis of pancreatic juice in the guideline algorithm significantly increased the specificity of detection of malignant IPMNs.

CONCLUSIONS

In a systematic review, we found cytologic analysis of pancreatic juice to have the greatest effect in increasing the specificity of detection of malignant IPMNs. We propose addition of this test to the Fukuoka guidelines for assessment of patients with IPMNs with worrisome features.

Germline Variants and Risk for Pancreatic Cancer: A Systematic Review and Emerging Concepts

Pancreatic cancer requires many genetic mutations. Combinations of underlying germline variants and environmental factors may increase the risk of cancer and accelerate the oncogenic process. We systematically reviewed, annotated, and classified previously reported pancreatic cancer-associated germline variants in established risk genes. Variants were scored using multiple criteria and binned by evidence for pathogenicity, then annotated with published functional studies and associated biological systems/pathways. Twenty-two previously identified pancreatic cancer risk genes and 337 germline variants were identified from 97 informative studies that met our inclusion criteria. Fifteen of these genes contained 66 variants predicted to be pathogenic (APC, ATM, BRCA1, BRCA2, CDKN2A, CFTR, CHEK2, MLH1, MSH2, NBN, PALB2, PALLD, PRSS1, SPINK1, TP53). Pancreatic cancer risk genes were organized into key biological mechanisms that promote pancreatic oncogenesis within an oncogenic model. Development of precision medicine approaches requires updated variant information within the framework of an oncogenic progression model. Complex risk modeling may improve interpretation of early biomarkers and guide pathway-specific treatment for pancreatic cancer in the future. Precision medicine is within reach.

Comparison of the Survival Outcomes of Pancreatic Cancer and Intraductal Papillary Mucinous Neoplasms

OBJECTIVES

The aims of the study were to compare survival outcomes between patients with pancreatic ductal adenocarcinoma (PDAC) and invasive intraductal papillary mucinous neoplasms (IPMN) and to determine candidates for adjuvant chemotherapy.

METHODS

A total of 579 consecutive patients, including 375 PDAC and 204 IPMN patients, were reviewed. Stage-matched comparisons of survival data were conducted using the Cox proportional hazards model and propensity analysis. To evaluate prognostic factors, univariate and multivariate Cox regression analyses were performed.

RESULTS

The overall survival for invasive IPMN was significantly longer than that for PDAC (hazard ratio, 2.34; P = 0.0001). When the analysis was limited to stage I patients, the 5-year overall survival rate of invasive IPMN patients was significantly better than that of PDAC patients (100% vs 74.1%, P = 0.0092); however, no difference was observed between stage II patients with invasive IPMN and PDAC (hazard ratio, 1.49; P = 0.09). The Cox proportional hazards model and propensity analysis demonstrated no difference in stage-matched survival. Multivariate analysis revealed that only T (≥3) was an independent prognostic factor for invasive IPMN.

CONCLUSIONS

Stage-matched analysis did not show a significant survival difference between invasive IPMN and PDAC patients, and T3 or higher was an independent prognostic factor for invasive IPMN.

Wuho/WDR4 deficiency inhibits cell proliferation and induces apoptosis via DNA damage in mouse embryonic fibroblasts

Wuho known as WDR4 encodes a highly conserved WD40-repeat protein, which has known homologues of WDR4 in human and mouse. Wuho-FEN1 interaction may have a critical role in the growth and development, and in the maintenance of genome stability. However, how Wuho gene deletion contributes to cell growth inhibition and apoptosis is still unknown. We utilized CAGGCre-ER transgenic mice have a tamoxifen-inducible cre-mediated recombination cassette to prepare primary mouse embryonic fibroblasts (MEFs) with Wuho deficiency. We have demonstrated that Wuho deficiency would induces γH2AX protein level elevation, heterochromatin relaxation and DNA damage down-stream sequences, including p53 activation, caspase-mediated apoptotic pathway, and p21-mediated G2/M cell cycle arrest.

Genetics of pancreatic cyst-cancer progression: standing on the shoulders of giants

PURPOSE OF REVIEW

Pancreatic cancer, despite years of study and some progress, presents with a grim prognosis in almost all cases. In the current review, we have discussed recent studies that have attempted to decipher the genetic makeup of pancreatic ductal adenocarcinoma and preneoplastic pancreatic cystic neoplasms.

RECENT FINDINGS

With the advent of high throughput sequencing, the genetic code of pancreatic cancer is beginning to unravel and this new-found information heralds an era of precision cancer care where treatment will be guided by the genetic code of the neoplasm. Results from these studies have pointed towards the complexity and heterogeneity of the pancreatic cancer genome, provided avenues to "tailor therapy" based as well as shed light on progression of preneoplastic pancreatic neoplasms into full blown invasive pancreatic ductal adenocarcinoma.

SUMMARY

While this progress has made us closer to the model of precision medicine, significant obstacles need to be overcome to use this new-found information to change the way we manage patients with pancreatic cancer.

Insights into the Pathogenesis of Pancreatic Cystic Neoplasms

With the current epidemic of diagnosed pancreatic cystic neoplasms on the rise, a substantial amount of work has been done to unravel their biology, thus leading to implications on clinical decision making. Recent genetic profiling of resected human specimens has identified alterations in signaling pathways involving KRAS and GNAS signaling as early events in the pathogenesis of intraductal pancreatic mucinous neoplasms. Progressively, mutations in genes such as TP53, SMAD4, RNF43, and others are thought to characterize invasive and advanced lesions. The role of inflammation in fueling the growth and transformation of these cysts has also begun to be studied with greater interest. A number of promising clinical studies have attempted to integrate these genetic insights into classifying these cysts and treating patients. We have reviewed existing literature on similar lines besides commenting on some useful animal models that recapitulate molecular and phenotypic progression of these cysts.

Resectable invasive IPMN versus sporadic pancreatic adenocarcinoma of the head of the pancreas: Should these two different diseases receive the same treatment? A matched comparison study of the French Surgical Association (AFC)

PURPOSE

To compare survival and impact of adjuvant chemotherapy in patients who underwent pancreaticoduodenectomy (PD) for invasive intraductal papillary mucinous neoplasm (IIPMN) and sporadic pancreatic ductal adenocarcinoma (PDAC).

METHODS

From 2005 to 2012, 240 patients underwent pancreatectomy for IIPMN and 1327 for PDAC. Exclusion criteria included neoadjuvant treatment, pancreatic resection other than PD, vascular resection, carcinoma in situ, or <11 examined lymph nodes. Thus, 82 IIPMN and 506 PDAC were eligible for the present study. Finally, The IIPMN group was matched 1:2 to compose the PDAC group according to TNM disease stage, perineural invasion, lymph node ratio, and margin status.

RESULTS

There was no difference in patient's characteristics, intraoperative parameters, postoperative outcomes, and histologic parameters. Overall survival and disease-free survival times were comparable between the 2 groups. In each group, overall survival time was significantly poorer in patients who did not achieve adjuvant chemotherapy (p = 0.03 for the IIPMN group; p = 0.03 for the PDAC group). In lymph-node negative patients of the IIPMN group, adjuvant chemotherapy did not have any significant impact on overall survival time (OR = 0.57; 95% CI [0.24-1.33]). Considering the whole population (i.e. patients with IIPMN and PDAC; n = 246), patients who did not achieve adjuvant chemotherapy had poorer survival (p < 0.01).

CONCLUSIONS

The courses of IIPMN and PDAC were similar after an optimized stage-to-stage comparison. Adjuvant chemotherapy was efficient in both groups. However, in lymph node negative patients, adjuvant chemotherapy seemed not to have a significant impact.

Enhanced karyopherin-α2 expression is associated with carcinogenesis in patients with intraductal papillary mucinous neoplasms

BACKGROUND/OBJECTIVES

Intraductal papillary mucinous neoplasms (IPMN) can become malignant. Karyopherin-α2 (KPNA2) plays a central role in nucleocytoplasmic transport and is associated with various types of cancer. The current study examined pancreatic KPNA2 expression in cancer patients and evaluated its association with clinicopathological factors, cancer cell proliferation.

METHODS

KPNA2 expression was investigated by immunohistochemistry in 40 surgically resected IPMN samples and its association with clinicopathological factors and Ki-67 expression were examined.

RESULTS

Eighteen IPMN samples (45% of patients) showed positive KPNA2 expression. KPNA2 expression levels in IPMN tissue with invasive carcinoma were significantly higher than those in adjacent normal tissues and in IPMN tissue with low-to high-grade dysplasia. KPNA2 expression correlated with pathological malignancy and Ki-67 labeling index and KPNA2 and Ki-67 expression was co-localized in nuclei. E2F were co-localized with KPNA2 in the IPMN tissues with high expression of KPNA2. KPNA2 expression was enhanced in the invasion front and in proliferating Ki-67-positive cells. In addition, KPNA2 expression in IPMN tissues was associated with older age, dilation of main pancreatic duct diameter, the presence of nodules, and histological type.

CONCLUSION

KPNA2 expression is associated with carcinogenesis of IPMN through the adenoma-carcinoma sequence.

Perspectives on the combination of radiotherapy and targeted therapy with DNA repair inhibitors in the treatment of pancreatic cancer

Pancreatic cancer is highly lethal. Current research that combines radiation with targeted therapy may dramatically improve prognosis. Cancerous cells are characterized by unstable genomes and activation of DNA repair pathways, which are indicated by increased phosphorylation of numerous factors, including H2AX, ATM, ATR, Chk1, Chk2, DNA-PKcs, Rad51, and Ku70/Ku80 heterodimers. Radiotherapy causes DNA damage. Cancer cells can be made more sensitive to the effects of radiation (radiosensitization) through inhibition of DNA repair pathways. The synergistic effects, of two or more combined non-lethal treatments, led to co-administration of chemotherapy and radiosensitization in BRCA-defective cells and patients, with promising results. ATM/Chk2 and ATR/Chk1 pathways are principal regulators of cell cycle arrest, following DNA double-strand or single-strand breaks. DNA double-stranded breaks activate DNA-dependent protein kinase, catalytic subunit (DNA-PKcs). It forms a holoenzyme with Ku70/Ku80 heterodimers, called DNA-PK, which catalyzes the joining of nonhomologous ends. This is the primary repair pathway utilized in human cells after exposure to ionizing radiation. Radiosensitization, induced by inhibitors of ATM, ATR, Chk1, Chk2, Wee1, PP2A, or DNA-PK, has been demonstrated in preclinical pancreatic cancer studies. Clinical trials are underway. Development of agents that inhibit DNA repair pathways to be clinically used in combination with radiotherapy is warranted for the treatment of pancreatic cancer.

Distinction of Invasive Carcinoma Derived From Intraductal Papillary Mucinous Neoplasms From Concomitant Ductal Adenocarcinoma of the Pancreas Using Molecular Biomarkers

OBJECTIVES

To clarify the usefulness of molecular biomarkers for distinguishing invasive carcinoma derived from intraductal papillary mucinous neoplasms (IPMNs [Inv-IPMN]) from concomitant pancreatic ductal adenocarcinoma (PDAC).

METHODS

Data from 19 patients with resected concomitant PDAC were retrospectively reviewed. KRAS/GNAS mutations and immunohistochemical (IHC) expression of p53 and p16/CDKN2A were assessed in both IPMN and distinct PDAC. As controls, KRAS/GNAS mutations and IHC labeling were assessed between invasive and noninvasive components in 1 lesion of 22 independent patients.

RESULTS

KRAS/GNAS mutation status of invasive and noninvasive components in Inv-IPMN was consistent in 18 (86%) of 21 patients. Conversely, mutational patterns in IPMN and distinct PDAC in the same pancreas differed from each other in 17 (89%) of 19. There were 10 (53%) and 8 (42%) of 19 patients who showed the same p53 and p16/CDKN2A staining between concomitant PDAC and distinct IPMN. In the Inv-IPMN cohort, 19 (86%) of 22 patients showed the same IHC expression pattern between the noninvasive and invasive components.

CONCLUSIONS

It may be possible to distinguish Inv-IPMN from concomitant PDAC by assessing these molecular biomarkers. More precise distinction of Inv-IPMN and concomitant PDAC will lead to adequate recognition of the natural history of IPMNs and hence optimal management.

Exploring the Functional Disorder and Corresponding Key Transcription Factors in Intraductal Papillary Mucinous Neoplasms Progression

This study has analyzed the gene expression patterns of an IPMN microarray dataset including normal pancreatic ductal tissue (NT), intraductal papillary mucinous adenoma (IPMA), intraductal papillary mucinous carcinoma (IPMC), and invasive ductal carcinoma (IDC) samples. And eight clusters of differentially expressed genes (DEGs) with similar expression pattern were detected by k-means clustering. Then a survey map of functional disorder in IPMN progression was established by functional enrichment analysis of these clusters. In addition, transcription factors (TFs) enrichment analysis was used to detect the key TFs in each cluster of DEGs, and three TFs (FLI1, ERG, and ESR1) were found to significantly regulate DEGs in cluster 1, and expression of these three TFs was validated by qRT-PCR. All these results indicated that these three TFs might play key roles in the early stages of IPMN progression.

Molecular pathology of intraductal papillary mucinous neoplasms of the pancreas

Since the first description of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas in the eighties, their identification has dramatically increased in the last decades, hand to hand with the improvements in diagnostic imaging and sampling techniques for the study of pancreatic diseases. However, the heterogeneity of IPMNs and their malignant potential make difficult the management of these lesions. The objective of this review is to identify the molecular characteristics of IPMNs in order to recognize potential markers for the discrimination of more aggressive IPMNs requiring surgical resection from benign IPMNs that could be observed. We briefly summarize recent research findings on the genetics and epigenetics of intraductal papillary mucinous neoplasms, identifying some genes, molecular mechanisms and cellular signaling pathways correlated to the pathogenesis of IPMNs and their progression to malignancy. The knowledge of molecular biology of IPMNs has impressively developed over the last few years. A great amount of genes functioning as oncogenes or tumor suppressor genes have been identified, in pancreatic juice or in blood or in the samples from the pancreatic resections, but further researches are required to use these informations for clinical intent, in order to better define the natural history of these diseases and to improve their management.

EZH2 is associated with malignant behavior in pancreatic IPMN via p27Kip1 downregulation

BACKGROUND

The epigenetic mechanism of tumorigenesis in pancreatic intraductal papillary mucinous neoplasm (IPMN) remains largely unknown. The aim of this study is to examine the role of enhancer of zeste homologue 2 (EZH2) alteration in pancreatic IPMN progression.

METHODS

Fifty-four surgically resected pancreatic IPMN specimens, including a total of 181 lesions (normal duct in 48, adenoma in 50, borderline atypia in 53, carcinoma in situ (CIS) in 19, and invasive carcinoma in 11) were analyzed by immunohistochemical staining (EZH2, Ki-67, p27Kip1). Using paraffin embedded sections, total RNA was successfully extracted from 20 IPMN lesions (borderline IPMN in 9, CIS in 6, invasive carcinoma in 5) and 7 pancreatic normal ducts, and then levels of EZH2 and p27Kip1 mRNA were analyzed by real time PCR.

RESULTS

In immunohistochemical analysis, cell proliferative activity revealed by Ki-67 positive nuclei was increased during IPMN progression (normal duct<adenoma<borderline atypia<CIS ≈ invasive carcinoma). EZH2 expression displayed a similar pattern (normal duct<adenoma<borderline atypia<CIS ≈ invasive carcinoma) with cell proliferative activity. EZH2 expression in malignant (CIS and invasive carcinoma) IPMNs was significantly higher than that in adenoma and borderline-atypia IPMNs. EZH2 expression level in IPMN lesions was positively correlated with the Ki-67 positive nuclear ratio (p<0.0001). EZH2-positive cells in malignant IPMN did not express p27Kip1. EZH2 mRNA expressions in malignant lesions were significantly higher than those in benign lesions (p<0.0001). In contrast, p27Kip1 mRNA in malignant lesions was significantly decreased compared to those in benign lesion (p<0.05), and there was an inverse correlation between EZH2 and p27Kip1 mRNA levels (p = 0.0109).

CONCLUSION

EZH2 is associated with the accelerated cell proliferation and malignant step in pancreatic IPMN via the downregulation of p27Kip1.

Pancreatic Cancer: Clinical Significance of Biomarkers

BACKGROUND

Improvement in the prognosis of patients with pancreatic cancer, novel effective screening and diagnostic strategies and treatments are needed. Recent advances in the understanding of pancreatic carcinogenesis and tumor microenvironment have allowed identification of biomarkers for screening, diagnosis and prediction of cancer treatments, including novel therapies targeting specific cancer or stromal cell subpopulations. Personalized therapy in pancreatic cancer is also promising as several drugs such as S1, capecitabine and gemcitabine reportedly have significant therapeutic effects. Predictive markers are thus needed to select patients most likely to benefit from therapies based on gemcitabine or other drugs.

SUMMARY

We review the clinical significance of promising screening, diagnostic, predictive and prognostic biomarkers based on genetic and epigenetic alterations and microRNA abnormalities in pancreatic cancer. We also review new types of biomarkers based on stromal cells, such as pancreatic stellate cells, in the microenvironment of pancreatic cancer.

Inhibition of checkpoint kinase 2 (CHK2) enhances sensitivity of pancreatic adenocarcinoma cells to gemcitabine

Checkpoint kinase 2 (CHK2) plays pivotal function as an effector of cell cycle checkpoint arrest following DNA damage. Recently, we found that co-treatment of NSC109555 (a potent and selective CHK2 inhibitor) potentiated the cytotoxic effect of gemcitabine (GEM) in pancreatic cancer MIA PaCa-2 cells. Here, we further examined whether NSC109555 could enhance the antitumour effect of GEM in pancreatic adenocarcinoma cell lines. In this study, the combination treatment of NSC109555 plus GEM demonstrated strong synergistic antitumour effect in four pancreatic cancer cells (MIA PaCa-2, CFPAC-1, Panc-1 and BxPC-3). In addition, the GEM/NSC109555 combination significantly increased the level of intracellular reactive oxygen species (ROS), accompanied by induction of apoptotic cell death. Inhibition of ROS generation by N-acetyl cysteine (NAC) significantly reversed the effect of GEM/NSC109555 in apoptosis and cytotoxicity. Furthermore, genetic knockdown of CHK2 by siRNA enhanced GEM-induced apoptotic cell death. These findings suggest that inhibition of CHK2 would be a beneficial therapeutic approach for pancreatic cancer therapy in clinical treatment.

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.

Hsp90 stabilizes Cdc25A and counteracts heat shock-mediated Cdc25A degradation and cell-cycle attenuation in pancreatic carcinoma cells

Pancreas cancer cells escape most treatment options. Heat shock protein (Hsp)90 is frequently over-expressed in pancreas carcinomas and protects a number of cell-cycle regulators such as the proto-oncogene Cdc25A. We show that inhibition of Hsp90 with geldanamycin (GD) destabilizes Cdc25A independent of Chk1/2, whereas the standard drug for pancreas carcinoma treatment, gemcitabine (GEM), causes Cdc25A degradation through the activation of Chk2. Both agents applied together additively inhibit the expression of Cdc25A and the proliferation of pancreas carcinoma cells thereby demonstrating that both Cdc25A-destabilizing/degrading pathways are separated. The role of Hsp90 as stabilizer of Cdc25A in pancreas carcinoma cells is further supported by two novel synthetic inhibitors 4-tosylcyclonovobiocic acid and 7-tosylcyclonovobiocic acid and specific Hsp90AB1 (Hsp90β) shRNA. Our data show that targeting Hsp90 reduced the resistance of pancreas carcinoma cells to treatment with GEM.

Genetic markers of malignant transformation in intraductal papillary mucinous neoplasm of the pancreas: a meta-analysis

OBJECTIVES

The objective of this study was to determine the relationship between specific genetic alterations and malignant transformation in intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

Quantitative meta-analysis was conducted of studies through October 2010 that adhered to the 1996 World Health Organization guidelines for distinguishing adenoma and borderline IPMN versus carcinoma in surgically resected specimens using a random-effects model. We developed a 6-point scoring system to assess study quality.

RESULTS

Thirty-nine studies (1235 IPMN samples) satisfied the inclusion criteria, and we conducted pooled analysis of 8 genetic markers: MUC1, MUC2, MUC5AC, kRas, p53, hTERT (human telomerase reverse transcriptase), cyclooxygenase 2, and Shh (Sonic hedgehog). Markers having the strongest association with malignant IPMN were hTERT (odds ratio [OR], 11.4; 95% confidence interval [CI], 3.5-36.7) and Shh (OR, 6.9; 95% CI, 2.4-20.2), whereas MUC5AC (OR, 1.0; 95% CI, 0.1-13.9) and kRas (OR, 2.0; 95% CI, 1.0-4.3) showed weak association with IPMN histologic progression.

CONCLUSIONS

Expression of hTERT is strongly associated with malignant transformation in IPMN, consistent with up-regulation of hTERT as a key step in progression of IPMN to cancer. Expression of kRas and MUC5AC is common but not strongly associated with IPMN histologic progression. The quality criteria used here may guide future reporting of genetic markers related to malignant transformation of IPMN.

Protein-protein interaction and SNP analysis in intraductal papillary mucinous neoplasm

Intraductal papillary mucinous neoplasm (IPMN) is a type of tumor that grows within the pancreatic ducts. It is a progress from hyperplasia to intraductal adenoma (IPMA), to noninvasive carcinoma, and ultimately to invasive carcinoma (IPMC). The objective of this study was to explore the molecular mechanism of the progression from IPMA to IPMC. By using the GSE19650 affymetrix microarray data accessible from Gene Expression Omnibus (GEO) database, we first identified the differentially expressed genes (DEGs) between IPMA and IPMC, followed by the protein-protein interaction and single-nucleotide polymorphism (SNP) analysis of the DEGs. Our study identified thousands of DEGs which involved regulation of cell cycle and apoptosis in this progression from IPMA to IPMC. Protein-protein interaction network construction found that MYC, IL6ST, NR3C1, CREBBP, GATA1 and LRP1 might play an important role in the progression. Furthermore, the SNP analysis confirmed the association between BRAC1 and pancreas cancer. In conclusion, our data provide a comprehensive bioinformatics analysis of genes and pathways which may be involved in the progression of IPMN from IPMA to IPMC.

Invasive carcinoma derived from intestinal-type intraductal papillary mucinous neoplasm is associated with minimal invasion, colloid carcinoma, and less invasive behavior, leading to a better prognosis

OBJECTIVES

Although intestinal-type intraductal papillary mucinous carcinoma (IPMC) is reported to have a better prognosis, few studies have addressed its invasive pattern. The meaning of "minimal invasion" (MI) in IPMC also remains unclear. We investigated the prognosis of intraductal papillary mucinous neoplasm (IPMN) focusing on MI and subtypes.

METHODS

We evaluated 71 patients with IPMC among a total of 179 patients with resected IPMN.

RESULTS

Although 2 of 10 MI-IPMC patients had lymph node metastasis, there were no disease-specific deaths among the MI-IPMC patients. Minimally invasive IPMCs were more frequently observed in intestinal-type IPMC (23/33 cases) than in non-intestinal-type IPMCs (16/38 cases; P = 0.019). Among 32 patients with massively invasive IPMC, the prognosis was significantly better for patients with intestinal-type IPMC than for patients with non-intestinal-type IPMC (P = 0.013). When confined to massively invasive IPMC, tubular invasion (P < 0.001) and lymphatic (P = 0.001) or serosal (P = 0.021) invasion were less frequently observed in intestinal-type IPMC than in non-intestinal-type IPMC.

CONCLUSIONS

Invasive carcinoma derived from intestinal-type IPMN is associated with MI, colloid carcinoma, and less invasive behavior.

CHEK2 gene alterations in the forkhead-associated domain, 1100delC and del5395 do not modify the risk of sporadic pancreatic cancer

Checkpoint kinase 2 gene (CHEK2) alterations increase risk of several cancer types. We analyzed selected CHEK2 alterations in 270 Czech pancreatic cancer patients and in 683 healthy controls. The pancreatic cancer risk was higher in individuals who inherited rare alterations in CHEK2 region involving forkhead-associated domain other than I157T (OR=5.14; 95% CI=0.94-28.23) but the observed association was non-significant (p=0.057). The most frequent I157T mutation did not alter the pancreatic cancer risk and neither the followed deletion of 5395bp nor c.1100delC were found in any of pancreatic cases. We conclude that the I157T, other alterations in its proximity, del5395 and c.1100delC in CHEK2 do not predispose to pancreatic cancer risk in the Czech population.

Molecular pathogenesis of intraductal papillary mucinous neoplasms of the pancreas

Over the last 3 decades, there have been substantial improvements in diagnostic imaging and sampling techniques to evaluate pancreatic diseases. The modern technology has helped us to recognize premalignant conditions of pancreas including mucinous cystic neoplasms and intraductal papillary mucinous neoplasms (IPMNs). Differentiation between benign and malignant lesions and early detection of any malignant transformation in premalignant lesion are extremely important for further management decisions. Diagnostic cytology has limited sensitivity to further differentiate between benign, premalignant, and malignant lesions of the pancreas. There is limited information about the epidemiological risk factors and molecular mechanisms leading to development and further progression to malignancy of IPMNs. Several studies have shown that pancreatic juice and pancreatic tissue from the lesion can be tested for molecular markers including K-ras, p53, and p16 to differentiate between cancer and chronic inflammatory process. We review cellular signaling pathways that contribute to pathogenesis of IPMNs of the pancreas to further identify potential biomarkers and molecular targets.

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.

Frequency of extrapancreatic neoplasms in intraductal papillary mucinous neoplasm of the pancreas: implications for management

OBJECTIVE

To estimate the frequency of extrapancreatic neoplasms in patients with IPMN compared with those with ductal pancreatic cancer and a general referral population.

SUMMARY BACKGROUND DATA

Several studies have reported an increased risk of extrapancreatic neoplasms in patients with IPMN, but these studies focused only on those patients who underwent resection and excluded those patients treated nonoperatively.

METHODS

All patients diagnosed with IPMN at Mayo Clinic from 1994 to 2006 were identified. Two control groups consisting of Group 1-patients with a diagnosis of ductal pancreatic adenocarcinoma (1:1) and Group 2-a general referral population (3:1) were matched for gender and age at diagnosis, year of registration, and residence. Logistic regression was used to assess the risk of a diagnosis of extrapancreatic neoplasms among cases versus controls.

RESULTS

There were 471 cases, 471 patients in Group 1, and 1413 patients in Group 2. The proportion of IPMN patients having any extrapancreatic neoplasm diagnosed before or coincident to the index date was 52% (95% CI, 47%-56%), compared with 36% (95% CI, 32%-41%) in Group 1 (P < 0.001), and 43% (95% CI, 41%-46%) in Group 2 (P = 0.002). Benign neoplasms most frequent in the IPMN group were colonic polyps (n = 114) and Barrett's neoplasia (n = 18). The most common malignant neoplasms were nonmelanoma skin (n = 35), breast (n = 24), prostate (n = 24), colorectal cancers (n = 19), and carcinoid neoplasms (n = 6).

CONCLUSIONS

Patients with IPMN have increased risk of harboring extrapancreatic neoplasms. Based on the frequency of colonic polyps, screening colonoscopy should be considered in all patients with IPMN.

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.

Differential protein immunoexpression profiles in appendiceal mucinous neoplasms: a special reference to classification and predictive factors

Appendiceal mucinous neoplasms have been the focus of considerable debate in recent years. We histologically classified 70 appendiceal mucinous neoplasms into three categories: 32 mucinous adenoma, 23 mucinous neoplasm of uncertain malignant potential, and 15 mucinous adenocarcinomas. Immunohistochemistry was performed for 24 proteins in different functional categories, specifically, oncogenic proteins (bcl-2, beta-catenin, CEA, C-erbB2, c-kit, Cox-2, Cyclin D1, EGFR, Ki-67, NF-kappaB, VEGF), tumor suppressors (E-cadherin, FHIT, hMLH1, p53, p63, smad4), cell-cycle regulators (p21, p27, p16), and mucin proteins (MUC1, MUC2, MUC5AC, MUC6). Our data showed that 9 out of the 24 proteins were more frequently altered in the mucinous adenocarcinoma group than in the mucinous adenoma group (P<0.05), including beta-catenin (13% in mucinous adenoma vs 60% in mucinous adenocarcinoma), CyclinD1 (44 vs 87%), Ki-67 (high labeling index: 31 vs 67%), NF-kappaB (19 vs 60%), VEGF (16 vs 87%), E-cadherin (0 vs 47%), p53 (6 vs 40%), MUC2 (9 vs 67%), and MUC5AC (3 vs 40%). The distinct immunoexpression profile of mucinous neoplasm of uncertain malignant potential was placed between those of mucinous adenoma and mucinous adenocarcinoma (P<0.05). Moreover, the mucinous adenoma, mucinous neoplasm of uncertain malignant potential, and mucinous adenocarcinoma categories displayed differences in terms of the number of altered markers among the nine proteins (P<0.05; mean 1.4 vs 2.6 vs 5.5, respectively). In mucinous adenocarcinoma, the p53 status was related to disease-free survival and overall survival of patients (P<0.05, both). NF-kappaB status and the number of altered protein markers made statistically marginal impacts on disease-free survival; also beta-catenin loss, on overall survival of patients. In conclusion, protein immunoexpression profiles may facilitate the classification of appendiceal mucinous neoplasms. In our study, the three tumor categories of mucinous adenoma, mucinous neoplasm of uncertain malignant potential, and mucinous adenocarcinoma exhibited distinct immunoexpression profiles. Five and more altered protein markers, p53 overexpression, NF-kappaB positivity, and beta-catenin loss were predictive factors of adverse clinical outcomes in appendiceal mucinous adenocarcinomas.

Update on the molecular pathogenesis of pancreatic tumors other than common ductal adenocarcinoma

PURPOSE

Although ductal adenocarcinoma is the most common and well known pancreatic tumor type, other distinct epithelial neoplasms affecting the pancreas that show different symptoms, biological behaviors and outcomes are becoming more frequently recognized and documented. Pancreatic epithelial tumors may be separated into ductal and nonductal neoplasms. The former group includes pancreatic ductal adenocarcinoma, intraductal papillary-mucinous tumor, mucinous cystic tumor and serous cystic tumor. The latter group includes pancreatic endocrine tumor, pancreatic acinar cell carcinoma, pancreatoblastoma and solid-pseudopapillary tumor. The aim of this review is to summarize recently acquired knowledge regarding the molecular characterization of these uncommon pancreatic epithelial neoplasms.

RECENT FINDINGS

Molecular studies of uncommon pancreatic epithelial tumors suggest that the different morphological entities are associated with distinct molecular profiles, highlighting the involvement of different molecular pathways leading to the development of each subtype of pancreatic neoplasm.

CONCLUSION

The correct classification of rare pancreatic epithelial tumors and the identification of their characteristic molecular aspects is the fundamental starting point in identifying novel diagnostic molecular tools and new targets for innovative therapeutic strategies.

Molecular biology of pancreatic cancer

Pancreatic cancer is a leading cause of cancer death. This devastating disease has the horrible honour of close to equal incidence and mortality rates. Late diagnosis and a constitutive resistance to every chemotherapy approach are responsible for this scenario. However, molecular biology tools in cooperation with translational efforts have dissected several secrets that underlie pancreatic cancer. Progressive acquisition of malignant, invasive phenotypes from pre-malignant lesions, recent revelations on core signalling pathways and new targeted designed trials offer a better future for pancreatic cancer patients. This review will summarise recent advances in the molecular biology of pancreatic cancer.

Intraductal papillary mucinous neoplasms

Intraductal papillary mucinous neoplasm (IPMN) is characterized by enhanced mucus secretion. It is a benign or low-grade neoplasm associated with a dilated main pancreatic duct, patulous ampullary orifice, and abundant mucus secretion. Foci of aggressive cancer may arise and become invasive. Surgery is the only treatment that can cure IPMN, but the extent of pancreatic resection and the intraoperative margins remain areas of controversy. The risks of total pancreatectomy must be weighed against the risk for developing cancer in the residual pancreas. Risks must be factored against the natural course of the disease and the likelihood of malignancy developing over the life expectancy.

Management of intraductal papillary mucinous neoplasms

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are being diagnosed with increasing frequency, probably due to the widespread use of cross-sectional imaging. The natural history of these tumors is still largely unknown. Several studies have shown topographical as well as biological differences between main duct and branch duct IPMNs. In the past few years, diagnostic work-up and, in particular, management of these tumors have evolved significantly. Data support the need for resection of main duct IPMNs and the possibility of nonoperative management in selected cases of branch duct tumors. In this systematic review, we analyze the most recent publications related to IPMNs, with particular emphasis on problems related to managing this challenging disease.