Tumor-suppressor genes in pancreatic cancer

Phytochemicals for the prevention and treatment of pancreatic cancer: Current progress and future prospects

Pancreatic cancer is the third leading cause of cancer-related deaths in the United States, owing to its aggressive nature and suboptimal treatment options, emphasizing the need for novel therapeutic approaches. Emerging studies have exhibited promising results regarding the therapeutic utility of plant-derived compounds (phytochemicals) in pancreatic cancer. The purpose of this review is to evaluate the potential of phytochemicals in the treatment and prevention of pancreatic cancer. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses was applied to collect articles for this review. Scholarly databases, including PubMed, Scopus and ScienceDirect, were queried for relevant studies using the following keywords: phytochemicals, phenolics, terpenoids, alkaloids, sulfur-containing compounds, in vitro, in vivo, clinical studies, pancreatic cancer, tumour, treatment and prevention. Aggregate results pooled from qualified studies indicate phytochemicals can inhibit pancreatic cancer cell growth or decrease tumour size and volume in animal models. These effects have been attributed to various mechanisms, such as increasing proapoptotic factors, decreasing antiapoptotic factors, or inducing cell death and cell cycle arrest. Notable signalling pathways modulated by phytochemicals include the rat sarcoma/mitogen activated protein kinase, wingless-related integration site/β-catenin and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signal transduction pathways. Clinically, phytochemicals have been found to increase survival while being well-tolerated and safe, though research is scarce. While these promising results have produced great interest in this field, further in-depth studies are required to characterize the anticancer activities of phytochemicals before they can be utilized to prevent or treat pancreatic cancer in clinical practice.

Effects of Smad4 on the expression of caspase‑3 and Bcl‑2 in human gingival fibroblasts cultured on 3D PLGA scaffolds induced by compressive force

Human gingival fibroblasts (HGFs) are the main cells that comprise gingival tissue, where they transfer mechanical signals under physiological and pathological conditions. The exact mechanism underlying gingival tissue reconstruction under compressive forces remains unclear. The present study aimed to explore the effects of Smad4, caspase-3 and Bcl-2 on the proliferation of HGFs induced by compressive force. HGFs were cultured on poly(lactide-co-glycolide) (PLGA) scaffolds under an optimal compressive force of 25 g/cm². Cell viability was determined via Cell Counting Kit-8 assays at 0, 12, 24, 48 and 72 h. The expression levels of Smad4, caspase-3 and Bcl-2 were measured via reverse transcription-quantitative PCR and western blotting. The application of compressive force on HGFs for 24 h resulted in a significant increase in cell proliferation and Bcl-2 expression, but a significant decrease in the expression of Smad4 and caspase-3; however, inverse trends were observed by 72 h. Subsequently, a lentivirus was used to overexpress Smad4 in HGFs, which attenuated the effects of compressive force on HGF proliferation and Bcl-2 expression, but enhanced caspase-3 expression, suggesting that Smad4 may regulate compressive force-induced apoptosis in HGFs. In conclusion, these findings increased understanding regarding the mechanisms of compressive force-induced HGF proliferation and apoptosis, which may provide further insight for improving the efficacy and stability of orthodontic treatment.

MiRNAs directly targeting the key intermediates of biological pathways in pancreatic cancer

Pancreatic Cancer (PC) is a severe form of malignancy all over the world. Delayed diagnosis and chemoresistance are the major factors contributing to its poor prognosis and high mortality rate. The genetic and epigenetic regulations of biological pathways further complicate the progression and chemotherapy response to this cancer. MicroRNAs (MiRNAs) involvement has been observed in all types of cancers including PC. The understanding and categorization of miRNAs according to their specific targets are very important to develop early diagnostic and therapeutic interventions. The current review, emphasizing recent research findings, has categorized miRNAs that directly target the potential onco-factors that act as central converging signal-nodes in five major cancer-related pathways i.e., MAPK/ERK, JAK/STAT, Wnt/β-catenin, AKT/mTOR, and TGFβ in PC. The therapeutic perspectives of miRNAs in PC have also been discussed. This will help to understand the interplay of various miRNAs within foremost signaling pathways and develop a multifactorial approach to treat difficult-to-treat PC.

MicroRNA in Pancreatic Cancer: From Biology to Therapeutic Potential

Pancreatic cancer is one of the most aggressive malignancies, accounting for more than 45,750 deaths annually in the U.S. alone. The aggressive nature and late diagnosis of pancreatic cancer, coupled with the limitations of existing chemotherapy, present the pressing need for the development of novel therapeutic strategies. Recent reports have demonstrated a critical role of microRNAs (miRNAs) in the initiation, progression, and metastasis of cancer. Furthermore, aberrant expressions of miRNAs have often been associated with the cause and consequence of pancreatic cancer, emphasizing the possible use of miRNAs in the effective management of pancreatic cancer patients. In this review, we provide a brief overview of miRNA biogenesis and its role in fundamental cellular process and miRNA studies in pancreatic cancer patients and animal models. Subsequent sections narrate the role of miRNA in, (i) cell cycle and proliferation; (ii) apoptosis; (iii) invasions and metastasis; and (iv) various cellular signaling pathways. We also describe the role of miRNA's in pancreatic cancer; (i) diagnosis; (ii) prognosis and (iii) therapeutic intervention. Conclusion section describes the gist of review with future directions.

Prognostic value of loss of heterozygosity and sub-cellular localization of SMAD4 varies with tumor stage in colorectal cancer

Background

Although loss of heterozygosity (LOH) at chromosome location 18q21 and decreased expression of SMAD4 in invasive colorectal cancers (CRCs) correlate with poor patient survival, the prognostic value of LOH at 18q21 and sub-cellular localization of SMAD4 have not been evaluated in relation to tumor stage.

Methods

Genomic DNA samples from 209 formalin-fixed, paraffin-embedded sporadic CRC tissues and their matching controls were analyzed for 18q21 LOH, and corresponding tissue sections were evaluated by immunohistochemistry for expression of SMAD4 and assessed for its sub-cellular localization (nuclear vs. cytoplasmic). In addition, 53 frozen CRCs and their matching control tissues were analyzed for their mutational status and mRNA expression of SMAD4. The phenotypic expression pattern and LOH status were evaluated for correlation with patient survival by the use of Kaplan-Meier and Cox regression models.

Results

LOH of 18q21 was detected in 61% of the informative cases. In 8% of the cases, missense point mutations were detected in Smad4. In CRCs, relative to controls, there was increased SMAD4 staining in the cytoplasm (74%) and decreased staining in the nuclei (37%). LOH of 18q21 and high cytoplasmic localization of SMAD4 were associated with shortened overall survival of Stage II patients, whereas low nuclear expression of SMAD4 was associated with worse survival, but only for patients with Stage III CRCs.

Conclusions

LOH of 18q21 and high cytoplasmic localization of SMAD4 in Stage II CRCs and low nuclear SMAD4 in Stage III CRCs are predictors of shortened patient survival.

Clinical implications of miRNAs in the pathogenesis, diagnosis and therapy of pancreatic cancer

Despite considerable progress being made in understanding pancreatic cancer (PC) pathogenesis, it still remains the 10th most often diagnosed malignancy in the world and 4th leading cause of cancer related deaths in the United States with a five year survival rate of only 6%. The aggressive nature, lack of early diagnostic and prognostic markers, late clinical presentation, and limited efficacy of existing treatment regimens make PC a lethal cancer with high mortality and poor prognosis. Therefore, novel reliable biomarkers and molecular targets are urgently needed to combat this deadly disease. MicroRNAs (miRNAs) are short (19-24 nucleotides) non-coding RNA molecules implicated in the regulation of gene expression at post-transcriptional level and play significant roles in various physiological and pathological conditions. Aberrant expression of miRNAs has been reported in several cancers including PC and is implicated in PC pathogenesis and progression, suggesting their utility in diagnosis, prognosis and therapy. In this review, we summarize the role of several miRNAs that regulate various oncogenes (KRAS) and tumor suppressor genes (p53, p16, SMAD4, etc.) involved in PC development, their prospective roles as diagnostic and prognostic markers and as a therapeutic targets.

Quantification of murine pancreatic tumors by high-resolution ultrasound

Ultrasonography is a powerful imaging modality that enables noninvasive, real-time visualization of abdominal organs and tissues. This technology may be adapted for use in mice through the utilization of higher frequency transducers, allowing for extremely high-resolution imaging of the mouse pancreas. This technique is particularly well suited to pancreas imaging due to the ultrasonographic properties of the normal mouse pancreas, easily accessible imaging planes for the head and tail of the mouse pancreas, and the comparative difficulty in imaging the mouse pancreas with other technologies. A suite of measurement tools is available to characterize the normal and diseased states of tissues. Of particular utility for cancer applications is the ability to use tomography to construct a 3D tumor volume, enabling longitudinal imaging studies to track tumor development, or response to therapies. Here, we describe a detailed method for performing high-resolution ultrasound to detect and measure pancreatic lesions in a genetically engineered mouse model of pancreatic ductal using the VisualSonics Vevo2100 High Resolution Ultrasound System. The method includes preparation of the animal for imaging, 2D and 3D image acquisition, and post-acquisition analysis of tumor volumes. The combined procedure has been utilized extensively by our group and others for the preclinical evaluation of novel therapeutic agents in the treatment of pancreatic ductal adenocarcinoma (Olive et al., Science 324:1457-1461, 2009; Cook et al., Methods Enzymol 439:73-85, 2008; Singh et al., Nat Biotechnol 28:585-593, 2010; Beatty et al., Science 331:1612-1616, 2011).

A study of Smad4, Smad6 and Smad7 in Surgically Resected Samples of Pancreatic Ductal Adenocarcinoma and Their Correlation with Clinicopathological Parameters and Patient Survival

Background

Smad4 is the common mediator of the tumor suppressive functions of TGF-beta. Smad6 and Smad7 are the antagonists of the TGF-beta pathway. This study investigates the differential protein expressions of Smad4, Smad6 and Smad7 in tumor as compared to normal tissue of pancreatic ductal adenocarcinoma (PDAC) and compares them with clinicopathological parameters and patient survival.

Results

There was a significant difference in protein expressions of Smad4 (p = 0.0001), Smad6 (p = 0.0015) and Smad7 (p = 0.0005) protein in tumor as compared to paired normal samples. Loss of Smad7 expression correlated significantly with tumor size (r = 0.421, p < 0.036) and margin status (r = 0.431; p < .032). Patients with moderate to high Smad4 protein expression had a better survival (median survival = 14.600 ± 2.112 months) than patients with absent or weak Smad4 protein expression (median survival = 7.150 ± 0.662). In addition, advanced disease stage correlated significantly with poor prognosis.

Conclusion

Loss of Smad4 significantly correlated with poor survival of PDAC patients. In the cases where Smad4 is expressed, Smad6 inhibition is possibly a novel mechanism for Smad4 inactivation. Smad7 has a role in pathobiology of PDAC. Further investigation in the roles of Smad6 and Smad7 would help in the identification of novel therapeutic targets for PDAC.

Experimental animal models of pancreatic carcinogenesis for prevention studies and their relevance to human disease

Pancreatic cancer is difficult to cure, so its prevention is very important. For this purpose, animal model studies are necessary to develop effective methods. Injection of N-nitrosobis(2-oxopropyl)amine (BOP) into Syrian golden hamsters is known to induce pancreatic ductal adenocarcinomas, the histology of which is similar to human tumors. Moreover, K-ras activation by point mutations and p16 inactivation by aberrant methylation of 5' CpG islands or by homozygous deletions have been frequently observed in common in both the hamster and humans. Thus, this chemical carcinogenesis model has an advantage of histopathological and genetic similarity to human pancreatic cancer, and it is useful to study promotive and suppressive factors. Syrian golden hamsters are in a hyperlipidemic state even under normal dietary conditions, and a ligand of peroxizome proliferator-activated receptor gamma was found to improve the hyperlipidemia and suppress pancreatic carcinogenesis. Chronic inflammation is a known important risk factor, and selective inhibitors of inducible nitric oxide synthase and cyclooxygenase-2 also have protective effects against pancreatic cancer development. Anti-inflammatory and anti-hyperlipidemic agents can thus be considered candidate chemopreventive agents deserving more attention.

Advances in pancreatitic intraductal papillary mucinous neoplasms

Intraductal papillary mucinous neoplasms (IPMNs) are a well-characterized group of intraductal mucin-producing cystic neoplasms of pancreas with clear malignant potential. It has a favorable prognosis and distinct molecular or clicinopathologic features compared with other types of pancreatic tumors. In addition, IPMNs can be divided into several subtypes in accordance with the papillary structure and mucin expression profile. Importantly, as IPMNs are acknowledged as key stages during pancreatic carcinogenesis, it can better reveal the mechanism and biological characteristics of IPMNs through further investigation of the pathologic features and the molecular aberrations harbored in different subtypes of IPMNs. This paper reviewed relevant literatures and elucidated its progression in terms of the molecular and clicinopathologic characteristics, diagnosis, treatment and prognosis of IPMNs.

Gene expression profiling of liver metastases and tumour invasion in pancreatic cancer using an orthotopic SCID mouse model

The prognosis of pancreatic adenocarcinoma is affected by early metastases and local tumour invasion beyond surgical margins. Gene expression profiling in pancreatic cancer tissue is complicated due to the high amount of RNAses being present in human tissue and that of suitable models. In order to demonstrate early metastases, the models should take into account the anatomical environment of the tumour. Using the orthotopic transplantation of pancreatic tumour cells in SCID (severe combined immunodeficiency) mice, these interactions are taken into consideration. In order to identify genes associated with local tumour invasion and metastases in ductal pancreatic cancer, we investigated a human pancreatic tumour cell line derived from an orthopic pancreatic tumour model in SCID mice. Differential gene expression was performed on the basis of microarray technique. The human MiaPaca-2 cell line was implanted orthotopically in SCID mice. Transcriptional profiling was performed on fresh frozen tissue derived from the primary tumour, the tumour invasion front and the liver metastases. Differentially expressed genes were identified using statistical analyses, and were validated with external databases and with immunohistochemistry. A total of 1066 of 14 500 genes were significantly differentially expressed. Comparing the primary tumour with the tumour invasion front, there were 614 statistically significant up- and 348 downregulated genes. Twenty-five statistically significant up- and 181 downregulated genes were identified comparing the liver metastases with the primary tumour. Eight genes (PAI-1, BNIP3l, VEGF, NSE, RGS4, HSP27, GADD45A, PTPN14) were chosen and validated in a semi-quantitative immunohistochemical analysis, which revealed a positive correlation to the array data. Overrepresentation analyses revealed a total of 66 significantly regulated pathways associated with cell proliferation, cell stress, cell communication metabolic and cytokine function. In conclusion, model marker genes for local invasion and liver metastases can be identified using transcriptional profiling in the SCID mouse. Overrepresentation analysis secures a good and fast overview about the significantly regulated genes and can assign genes to certain pathways. These marker genes can be related to the apoptotic cascade, angiogenesis and cell interaction.

The angiogenic switch molecule, secreted FGF-binding protein, an indicator of early stages of pancreatic and colorectal adenocarcinoma

Tumor angiogenesis has been related to the initiation as well as progression toward more aggressive behavior of human tumors. We will discuss genetic events underlying the initiation and progression of colorectal and pancreatic adenocarcinoma with a particular focus on the modulation of angiogenesis. A secreted fibroblast growth factor (FGF) binding protein (FGF-BP), which is an extracellular chaperone molecule for FGFs, has been shown to enhance FGF-mediated biochemical and biologic events and to be a crucial rate-limiting factor for tumor-dependent angiogenesis. Histochemical and in situ hybridization studies with archival samples show that FGF-BP is induced early during the initiation of colorectal and pancreatic adenocarcinoma. We will discuss the potential of this secreted protein as a serum marker to identify at-risk subjects.

Solid type clear cell carcinoma of the pancreas: differential diagnosis of an unusual case and review of the literature

Pancreatic neoplasms have been reliably classified on the basis of their histopathology and immunophenotype. In this study, we report on a pancreatic tumor whose phenotype and genotype could not be assigned to any known tumor entity. The tumor was observed in the pancreatic head of a 54-year-old woman. It was found to be a solid infiltrating carcinoma with abundant clear cells. Apart from cytokeratin, the tumor cells expressed vimentin, S100, and MUC-1. DNA microarray analysis revealed a transcription profile clearly differing from that of normal pancreatic tissue and pancreatic ductal adenocarcinoma. Despite metastatic behavior, the tumor displayed a more favorable course than conventional pancreatic ductal adenocarcinoma. We suggest that this tumor be called solid type clear cell carcinoma of the pancreas.

Gain of chromosome 8q: a potential prognostic marker in resectable adenocarcinoma of the pancreas?

BACKGROUND

The objective of this study was to identify genomic alterations in resectable pancreatic cancer (PCA). Chromosomal imbalances were correlated with histopathological and clinical data to verify their prognostic significance.

METHODS

Specimens of 33 PCA were investigated by comparative genomic hybridization. Microdissection was used for separation of PCA from the normal cells before isolation of DNA; nick-end labeling and hybridization were performed according to standard protocols. Aberrations were correlated with staging and grading using log-rank test and Cox regression. Survival rates were plotted using the Kaplan-Meier method.

RESULTS

Twenty-eight (85%) PCA showed aberrations. Gains of chromosomal material were most frequently identified on 8q (42%), 13q (30%), 18p (21%), and 3q (18%). Genetic losses were frequently detected on 1p (45%), 22 (42%), 19 (36%), 17p (27%), 18q and 8p (15% each), and 3p (12%). Losses of 8p (n = 5) and 3p (n = 4) were only detected in stages III and IV (P < 0.05). Median survival time of all patients was 13 months. Median survival time of patients with aberration of 8q (n = 14) was 8.5 months compared to 16 months in patients without gain of 8q (n = 19; P = 0.029).

CONCLUSIONS

The chromosomal regions containing genetic alterations represent potential loci for new target genes in PCA. The significant correlation of gain of chromosome 8q with short survival time suggests that 8q may be a new marker to assess prognosis and malignant potential of resected PCA in the individual patient, thereby helping to identify patients at risk for recurrence that might profit from adjuvant therapy.

Proteomics studies of pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer death in the United States, with 4% survival 5 years after diagnosis. Biomarkers are desperately needed to improve earlier, more curable cancer diagnosis and to develop new effective therapeutic targets. The development of quantitative proteomics technologies in recent years offers great promise for understanding the complex molecular events of tumorigenesis at the protein level, and has stimulated great interest in applying the technology for pancreatic cancer studies. Proteomic studies of pancreatic tissues, juice, serum/plasma, and cell lines have recently attempted to identify differentially expressed proteins in pancreatic cancer to dissect the abnormal signaling pathways underlying oncogenesis, and to detect new biomarkers. It can be expected that the continuing evolution of proteomics technology with better resolution and sensitivity will greatly enhance our capability in combating pancreatic cancer.

Tumor angiogenesis: initiation and targeting - therapeutic targeting of an FGF-binding protein, an angiogenic switch molecule, and indicator of early stages of gastrointestinal adenocarcinomas -

Tumor angiogenesis has been related to the initiation as well as progression toward more aggressive behavior of human tumors. In particular, the activity of angiogenic factors is crucial for tumor progression. We previously characterized a secreted fibroblast growth factor-binding protein (FGF-BP) as a chaperone molecule, which binds to various FGFs, enhances FGF-mediated biochemical and biologic events and importantly is a crucial rate-limiting factor for tumor-dependent angiogenesis. We generated monoclonal antibodies that target FGF-BP protein and used them as a tool to evaluate frequency and pattern of FGF-BP expression during the malignant progression of pancreas and colorectal carcinoma in archival tissue samples. We found that FGF-BP is dramatically upregulated during the initiation of colorectal and pancreatic adenocarcinoma. Crucial genetic events underlying the initiation and progression of colorectal and pancreatic adenocarcinoma with a particular focus on the modulation of angiogenesis and antiangiogenic therapies are discussed. We propose that the upregulation of the secreted FGF-BP protein during early phases of pancreas and colon cancer could make this protein a possible serum marker indicating the presence of high-risk premalignant lesions. Furthermore, the biological activity of FGF-BP is neutralized by monoclonal antibodies suggesting the potential for antibody-based therapeutic targeting.

Expression of transforming growth factor-beta-1 and p27Kip1 in pancreatic adenocarcinomas: relation with cell-cycle-associated proteins and clinicopathologic characteristics

Background

The purpose of our study was to investigate the immunohistochemical expression of TGF-β1 and p27 in pancreatic adenocarcinomas and to compare the findings with the clinicopathological features and survival. We also aimed to evaluate the expression of TGF-β1 and p27 in the context of other cell cycle and proliferation markers such as cyclin D1 and Ki-67.

Methods

We examined TGF-β1 and p27 expression immunohistochemically in 63 cases of invasive ductal adenocarcinoma of the pancreas. Standard streptavidin-biotin immunperoxidase method was used for immunostaining and the stained slides were examined microscopically using semiquantitative criteria.

Results

TGF-β1 stained the cytoplasms of the tumor cells in 43 cases [68.3%]. There was a statistically significant difference among TGF-β1 staining scores in terms of clinicopathologic factors such as blood vessel invasion, stage and distant metastasis [p < 0.05]. Of the 63 tumors evaluated 23 [36.5%] were positive for p27 within the nucleus. An inverse correlation was found between p27 immunoreactivity and grade [p < 0.05]. But no significant correlation was found between p27 and other parameters. Among the patients with survival data 27 patients had RO resections and these cases were considered in survival analysis. In the univariate analysis, neither TGF-β1 nor p27 expression was related with patient survival.

Conclusion

Our findings suggest that in pancreatic carcinoma, TGF-β1 expression is related to tumor growth and metastasis. But it is not associated with cell cycle proteins. p27 expression is reduced in pancreatic adenocarcinomas and decreased protein levels of p27 may play a role in the differentiation of pancreatic cancer.

Gene expression profiling of microdissected pancreatic ductal carcinomas using high-density DNA microarrays

Pancreatic ductal adenocarcinoma (PDAC) remains an important cause of malignancy-related death and is the eighth most common cancer with the lowest overall 5-year relative survival rate. To identify new molecular markers and candidates for new therapeutic regimens, we investigated the gene expression profile of microdissected cells from 11 normal pancreatic ducts, 14 samples of PDAC, and 4 well-characterized pancreatic cancer cell lines using the Affymetrix U133 GeneChip set. RNA was extracted from microdissected samples and cell lines, amplified, and labeled using a repetitive in vitro transcription protocol. Differentially expressed genes were identified using the significance analysis of microarrays program. We found 616 differentially expressed genes. Within these, 140 were also identified in PDAC by others, such as Galectin-1, Galectin-3, and MT-SP2. We validated the differential expression of several genes (e.g., CENPF, MCM2, MCM7, RAMP, IRAK1, and PTTG1) in PDAC by immunohistochemistry and reverse transcription polymerase chain reaction. We present a whole genome expression study of microdissected tissues from PDAC, from microdissected normal ductal pancreatic cells and pancreatic cancer cell lines using high-density microarrays. Within the panel of genes, we identified novel differentially expressed genes, which have not been associated with the pathogenesis of PDAC before.

Microarray-based gene expression profiling in pancreatic ductal carcinoma: status quo and perspectives

BACKGROUND

Pancreatic ductal adenocarcinoma has an extremely poor prognosis. To improve the prognosis, novel molecular markers and targets for earlier diagnosis and adjuvant and/or neoadjuvant treatment need to be identified. One of the key techniques that has been developed to achieve this goal is DNA microarray profiling, which is used to identify the mechanisms of deregulated molecular functions in pancreatic carcinoma cells.

OBJECTIVE

As several studies using microarrays have already been published, this review attempts to compare published data and crossvalidate the results. In addition, the applied techniques are discussed.

Biologically Different Subgroups of Invasive Ductal Carcinoma of the Pancreas

PURPOSE

Among invasive ductal carcinomas of the pancreas (IDCP), there is a morphologically characteristic subgroup accompanied by abundant intraductal carcinoma components (ICCs). With the aim of determining whether ICC-rich IDCP are biologically different from ICC-poor IDCP, the expression status of Dpc4 protein was analyzed.

EXPERIMENTAL DESIGN

A total of 43 IDCP was subdivided into two groups: (a). ICC-rich IDCP (ICCs area occupies >or=10% of the entire tumorous area); and (b). ICC-poor IDCP (with <10% of ICCs area). A total of 10 invasive carcinomas derived from intraductal papillary-mucinous neoplasms (ICs from IPMNs) were also analyzed. Each invasive and intraductal carcinoma area was then evaluated for Dpc4 protein status by immunohistochemistry.

RESULTS

In a total of 43 IDCP, there were 23 ICC-rich IDCP and 20 ICC-poor IDCP. Dpc4-positive immunostaining was observed in the invasive carcinoma component of ICC-rich IDCP, ICC-poor IDCP, and ICs from IPMN in 18 of 23 (78%), 4 of 20 (20%), and 7 of 10 (70%) cases, respectively. In the intraductal component, positive staining for Dpc4 was found in 20 of 23 (87%), 3 of 7 (41%), and 8 of 10 (80%) cases, respectively. Dpc4 expression was found in both the invasive and ICC components of ICC-rich IDCP, similar to that found in IC derived from IPMN, whereas the expression of Dpc4 was largely diminished in ICC-poor IDCP.

CONCLUSIONS

Morphologically distinct subgroups of invasive ductal carcinomas of the pancreas, namely ICC-rich IDCP and ICC-poor IDCP, are also biologically distinguishable as revealed by the differential expression of Dpc4.

ADAM9 expression in pancreatic cancer is associated with tumour type and is a prognostic factor in ductal adenocarcinoma

Gene expression profiling revealed ADAM9 to be distinctly overexpressed in pancreatic ductal adenocarcinoma (PDAC). We examined the relevance of ADAM9 expression in PDAC diagnosis and prognosis. A total of 59 infiltrating PDACs, 32 specimens from patients with chronic pancreatitis, 11 endocrine tumours and 24 acinar cell carcinomas were immunohistochemically analysed for ADAM9 expression. Staining for ADAM9 was detected in 58 out of 59 (98.3%) PDACs and in two out of 24 (8.3%) acinar cell carcinomas, but not in endocrine tumours. In the non-neoplastic pancreas, whether normal or chronically inflamed, ADAM9 was expressed in centroacinar and intralobular duct cells, but not in interlobular duct cells and their hyperplastic lesions. Pancreatic ductal adenocarcinomas showing cytoplasmic ADAM9 expression correlated with poor tumour differentiation and also with shorter overall survival than in cases showing only an apical membranous staining pattern (P=0.001). Multivariate analysis identified cytoplasmic ADAM9 expression as an independent marker of shortened survival in a set of 42 curatively (R0) resected PDAC (P<0.05, hazard ratio 2.85, 95% confidence interval: 1.21–6.71). The results show that ADAM9 expression distinguishes PDACs from other solid pancreatic tumours. In addition, cytoplasmic ADAM9 overexpression is associated with poor differentiation and shortened survival. Therefore, ADAM9 overexpression might contribute to the aggressiveness of PDACs.

Immunohistochemical analysis of adenocarcinoma of the small intestine: a tissue microarray study

BACKGROUND

Primary adenocarcinomas of the small intestine are rare, and the genetic mechanisms involved in their carcinogenesis remain unclear.

AIM

To examine the expression of candidate proteins in small intestinal adenocarcinomas by immunohistochemistry performed on tissue microarrays (TMAs).

METHODS

Twenty seven primary sporadic small intestinal adenocarcinomas were analysed. The TMA technique was validated by comparing immunohistochemical labelling of hMLH1 and hMSH2 on TMAs and the tissue sections they derived from. The expression of Smad4, hMSH6, beta catenin, and p53 was investigated and results compared with those obtained in 14 malignant ampullary tumours.

RESULTS

TMA technology with threefold redundancy adequately represented the immunohistochemical pattern of small intestinal adenocarcinomas. Loss of hMLH1 expression, but not hMSH2 or hMSH6, was seen in two of 27 small intestinal adenocarcinomas. All ampullary tumours showed nuclear staining for hMSH2 and hMSH6. One case showed lack of immunostaining for hMLH1. Smad4 expression was absent in five small intestinal adenocarcinomas and two ampullary tumours. Overexpression of p53 was detected in the nuclei of 14 of the 27 small intestinal adenocarcinomas, and five of the 14 ampullary tumours. Nuclear or cytoplasmic expression of beta catenin was present in all specimens.

CONCLUSION

Inactivation of the SMAD4/DPC4 gene seems to be involved in small intestinal adenocarcinoma tumorigenesis. Overexpression of p53 and abnormal expression of beta catenin are two common events, unlike the loss of expression of the DNA mismatch repair proteins (hMLH1, hMSH2, and hMSH6). The carcinogenetic process appears to be similar in small intestinal adenocarcinomas and malignant ampullary tumours.

Molecular pathogenesis of precursor lesions of pancreatic ductal adenocarcinoma

Precursor lesions are assuming greater importance in the study of pancreatic ductal adenocarcinoma. As pancreatic cancer is almost universally fatal due to late clinical presentation and biological aggressiveness, characterisation of its precursor lesions may create scope for early diagnosis and improved outcome with conventional therapies as well as the development of novel therapeutic and preventative strategies. Pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous tumours (IPMTs) are thought to be precursor lesions of ductal adenocarcinoma of the pancreas. Recent work has focused on the molecular aberrations associated with these lesions leading to the formulation of a progression model for pancreatic cancer. Progressive histopathological changes along the progression model are associated with aberrations of cell cycle regulatory and growth factor signalling molecules that occur in pancreatic cancer at high frequency and are common to many cancers. Characterisation of these molecular aberrations provides scope for the development of novel diagnostic and treatment strategies that will ultimately impact on the outcome for people who develop pancreatic cancer.

Gene expression profiles of microdissected pancreatic ductal adenocarcinoma

In a search for new molecular markers of pancreatic ductal adenocarcinoma (PDAC), we compared the gene expression profiles of seven pancreatic carcinomas and one carcinoma of the papilla Vateri with those of duct cells from three non-neoplastic pancreatic tissues. In addition, the human pancreatic duct cell line and five PDAC cell lines (AsPC-1, BxPC-3, Capan-1, Capan-2, HPAF) were examined. RNA was extracted from microdissected tissue or cultured cell lines and analysed using a custom-made Affymetrix Chip containing 3023 genes, of which 1000 were known to be tumour associated. Hierarchical clustering revealed 81 differentially expressed genes. Of all the genes, 26 were downregulated in PDAC and 14 were upregulated in PDAC. In PDAC cell lines versus normal pancreatic duct cells, 21 genes were downregulated and 20 were upregulated. Of these 81 differentially expressed genes, 15 represented human genes previously implicated in the tumourigenesis of PDAC. From the genes that were so far not known to be associated with PDAC tumorigenesis, we selected ADAM9 for further validation because of its distinct overexpression in tumour tissue. Using immunohistochemistry, the over-expressed gene, ADAM9, was present in 70% of the PDACs analysed. In conclusion, using microarray technology we were able to identify a set of genes whose aberrant expression was associated with PDAC and may be used to target the disease.

Frequent RASSF1A promoter hypermethylation and K-ras mutations in pancreatic carcinoma

Recently, we have characterized the Ras association domain family 1A gene (RASSF1A) at the segment 3p21.3, which is frequently lost in variety of human cancers and epigenetically inactivated in many types of primary tumors, such as lung, breast, kidney, prostate and thyroid carcinomas. Here, we investigated the methylation status of the RASSF1A CpG island promoter in the pathogenesis of pancreatic cancer. RASSF1A hypermethylation was detected in 29 out of 45 (64%) primary adenocarcinomas, in 10 out of 12 (83%) endocrine tumors and in eight out of 18 (44%) pancreatitis samples. In seven out of eight pancreas cancer cell lines, RASSF1A was silenced and was retranscribed after treatment with 5-aza-2'-deoxycytidine. Additionally, we analysed the aberrant methylation frequency of cell cycle inhibitor p16(INK4a) and K-ras gene mutations in the pancreatic samples. p16 inactivation was detected in 43% of adenocarcinomas, in 17% of neuroendocrine tumors, in 18% of pancreatitis and in 63% of pancreas cancer cell lines. K-ras mutations were detected in 16 out of 45 (36%) primary adenocarcinomas. Pancreatic adenocarcinomas with K-ras mutation have significantly less RASSF1A methylation and vice versa (P=0.001, chi(2) test). In conclusion, our data indicate that inactivation of the RASSF1A gene is a frequent event in pancreatic cancer and suggest an inverse correlation between RASSF1A silencing and K-ras activation.

Increased expression of alpha-1-antitrypsin, glutathione S-transferase pi and vascular endothelial growth factor in human pancreatic adenocarcinoma

BACKGROUND

This study was designed to investigate abnormalities in gene expression in ductal adenocarcinoma of the pancreas using cDNA arrays.

METHODS

Gene expression in pancreatic ductal adenocarcinoma was compared with normal pancreatic tissue controls. Specimens from 5 patients with pancreatic adenocarcinoma were taken fresh at operation and analyzed using commercially prepared cDNA arrays evaluating approximately 2,000 genes. Immunohistochemical staining was used to confirm protein expression of selected genes.

RESULTS

Alpha-1-antitrypsin (A1AT) and glutathione S-transferase pi (GSTP) were significantly up-regulated in all 5 tumors. Vascular endothelial growth factor (VEGF) was up-regulated in 4 of the 5 patients. Immunohistochemical staining verified the overexpression of each of these genes.

CONCLUSIONS

A1AT, GSTP, and VEGF are overexpressed in human pancreatic adenocarcinoma specimens taken fresh at operation. To our knowledge, this is the first study of human pancreatic ductal adenocarcinoma demonstrating the up-regulation of these genes using gene expression arrays.

Immunohistochemical labeling for the Dpc4 gene product is a specific marker for adenocarcinoma in biopsy specimens of the pancreas and bile duct

We immunohistochemically labeled 72 biopsy specimens from the extrahepatic biliary tree and pancreas for Dpc4 protein and correlated expression with histologic diagnosis and patient follow-up. Specimens were classified histologically as follows: nonneoplastic, 35; neoplastic, 22; atypical, 15. Loss of expression of Dpc4 protein was identified in 12 specimens; 11 were histologically diagnostic of carcinoma. The 12th specimen was from a patient whose biopsy specimen initially was diagnosed as "atypical," but clinical follow-up revealed adenocarcinoma. Of the 12 atypical biopsy specimens with intact expression for Dpc4, follow-up later revealed that 10 were adenocarcinoma. Loss of expression of Dpc4 protein was never identified in a benign specimen. Immunohistochemical labeling for the Dpc4 gene product is a specific marker of carcinoma in biopsy specimens of the pancreas and extrahepatic bile ducts and is marginally helpful in classifying atypical specimens. The sensitivity for carcinoma is low. This latter finding is not unexpected, because the DPC4 tumor suppressor gene is inactivated in only about half of pancreatic and biliary malignant neoplasms. Importantly, loss of Dpc4 expression has been reported in in situ carcinomas, suggesting that loss of expression should not be equated with invasive carcinoma.

Loss of Dpc4 expression in colonic adenocarcinomas correlates with the presence of metastatic disease

DPC4 is a candidate tumor suppressor gene on chromosome 18q21, a region that shows high frequencies of allelic losses in pancreatic and colorectal adenocarcinomas. Biallelic inactivation of DPC4 has been reported in half of pancreatic cancers, but are relatively infrequent in other tumor types. The role of DPC4 inactivation in colorectal neoplasms has not been fully characterized. An immunohistochemical assay for Dpc4 protein expression has been recently developed and shown to be a sensitive and specific surrogate for alterations in the DPC4 gene. In this study we examined the expression of Dpc4 protein in formalin-fixed archival tissue from 83 colorectal lesions, including 19 adenomas and 64 sporadic adenocarcinomas (11 stage I, 13 stage II, 17 stage III, and 23 stage IV cancers). None of the adenomas or stage I adenocarcinomas showed loss of Dpc4 expression, whereas one of 13 (8%) stage II, one of 17 (6%) stage III, and five of 23 (22%) of stage IV cancers showed loss of Dpc4 expression. There was a borderline significant difference in loss of Dpc4 reactivity in colorectal tumors with distant metastasis at presentation (22%) versus primary tumors without distant metastasis (5%) (Fisher's exact test, P = 0.05; chi(2) = 0.04). Poorly differentiated histology or status of pericolonic lymph nodes did not affect Dpc4 expression. Alterations in DPC4 are involved in the progression of a subset of colorectal carcinomas, especially those that present with advanced disease. In the sequential pathogenesis of colorectal tumors, inactivation of DPC4 is likely to be a late event.

Immunohistochemical labeling for dpc4 mirrors genetic status in pancreatic adenocarcinomas : a new marker of DPC4 inactivation

DPC4 (MADH4, SMAD4) is a tumor suppressor gene inactivated by allelic loss in approximately 55% of pancreatic adenocarcinomas. Unfortunately, it can be technically very difficult to detect the inactivation of DPC4 at the genetic level because genetic analyses require the microdissection of relatively pure samples of neoplastic and normal tissues. This is especially true for pancreatic adenocarcinomas, which elicit vigorous, non-neoplastic, stromal responses. Immunohistochemical labeling can overcome this hurdle because it preserves morphological information. We therefore studied the expression of the DPC4 gene product in 46 cancers, including 5 cancer cell lines by Western blot analysis and 41 primary periampullary adenocarcinomas by immunohistochemistry. The status of exons 1-11 of the DPC4 gene in all 46 of the cancers had been previously characterized at the molecular level, allowing us to correlate Dpc4 expression directly with gene status. Three cell lines had wild-type DPC4 genes, and Dpc4 expression was detected in all three by Western blot. The two cell lines with homozygously deleted DPC4 genes did not show Dpc4 protein by Western blot analysis. Immunohistochemical labeling revealed that 17 (94%) of the 18 primary adenocarcinomas with wild-type DPC4 genes expressed the DPC4 gene product, whereas 21 (91%) of 23 primary adenocarcinomas with inactivated DPC4 genes did not. Cases in which there was discordance between the immunohistochemical labeling and the genetic analyses were reanalyzed genetically, and we identified a deletion in exon 0 of DPC4 in one of these cases. This is the first report of a mutation in exon 0 of DPC4 in a pancreatic cancer. The contrast between the strong expression of Dpc4 by normal tissues and the loss of expression in the carcinomas was highlighted in several cases in which an infiltrating cancer was identified growing into a benign duct. These observations suggest that immunohistochemical labeling for the DPC4 gene product is an extremely sensitive and specific marker for DPC4 gene alterations in pancreatic carcinomas. The sensitivity and specificity of immunohistochemical labeling for Dpc4 in other periampullary carcinomas has yet to be determined.