Epithelial-mesenchymal transition (EMT) and activated extracellular signal-regulated kinase (p-Erk) in surgically resected pancreatic cancer

Nerve growth factor regulates CD133 function to promote tumor cell migration and invasion via activating ERK1/2 signaling in pancreatic cancer

BACKGROUND

Perineural invasion (PNI) is extremely high frequency among the various metastatic routes in pancreatic cancer. Nerve growth factor, secreted by astroglial cells, exerts effects on tumor invasion in some cancer cells, but its function on migration and invasion in pancreatic cancer is still unclear. In the present study, we determined the effects of NGF on modulating tumor cell metastatic potential and invasion activity and explored its mechanisms in pancreatic cancer.

METHODS

NGF and CD133 expression were detected in tumor tissues using immunohistochemical analysis and Western blotting analysis. The effects of NGF on the regulation of CD133 expression and the promotion of cancer migration and invasion were investigated using wound healing and matrigel transwell assay. A related mechanism that NGF regulates CD133's function via activating ERK1/2 signaling also was observed.

RESULTS

NGF/CD133 is overexpressed in human pancreatic cancer and promotes the migration and invasion of human pancreatic cancer cells through the activation of the ERK/CD133 signaling cascade. NGF/ERK signaling modulates the cancer cell EMT process, migration and invasion through the regulation of CD133 expression and its subcellular localization.

CONCLUSIONS

NGF/CD133 signaling initiated the migration and invasion of pancreatic cancer cells. NGF/CD133 might be an effective and potent therapeutic target for pancreatic cancer metastasis, particularly in PNI.

Epithelial-mesenchymal transition of ovarian cancer cells is sustained by Rac1 through simultaneous activation of MEK1/2 and Src signaling pathways

Epithelial-mesenchymal transition (EMT) is regarded as a crucial contributing factor to cancer progression. Diverse factors have been identified as potent EMT inducers in ovarian cancer. However, molecular mechanism sustaining EMT of ovarian cancer cells remains elusive. Here, we show that the presence of SOS1/EPS8/ABI1 complex is critical for sustained EMT traits of ovarian cancer cells. Consistent with the role of SOS1/EPS8/ABI1 complex as a Rac1-specific guanine nucleotide exchange factor, depleting Rac1 results in the loss of most of mesenchymal traits in mesenchymal-like ovarian cancer cells while expressing constitutively active Rac1 leads to EMT in epithelial-like ovarian cancer cells. With the aid of clinically tested inhibitors targeting various EMT-associated signaling pathways, we show that only combined treatment of MEK1/2 and Src inhibitors can abolish constitutively active Rac1-led EMT and mesenchymal traits displayed by mesenchymal-like ovarian cancer cells. Further experiments also reveal that EMT can be induced in epithelial-like ovarian cancer cells by co-expressing constitutively active MEK1 and Src rather than either alone. As the activities of Erk and Src are higher in ovarian cancer cells with constitutively active Rac1, we conclude that Rac1 sustains ovarian cancer cell EMT through simultaneous activation of MEK1/2 and Src signaling pathways. Importantly, we demonstrate that combined use of MEK1/2 and Src inhibitors effectively suppresses development of intraperitoneal xenografts and prolongs the survival of ovarian cancer-bearing mice. This study suggests that cocktail of MEK1/2 and Src inhibitors represents an effective therapeutic strategy against ovarian cancer progression.

Can Molecular Biomarkers Change the Paradigm of Pancreatic Cancer Prognosis?

Pancreatic ductal adenocarcinoma is one of the most lethal types of tumour, and its incidence is rising worldwide. Although survival can be improved when these tumours are detected at an early stage, this cancer is usually asymptomatic, and the disease only becomes apparent after metastasis. The only prognostic biomarker approved by the FDA to date is carbohydrate antigen 19-9 (CA19-9); however, the specificity of this biomarker has been called into question, and diagnosis is usually based on clinical parameters. Tumour size, degree of differentiation, lymph node status, presence of distant metastasis at diagnosis, protein levels of KI-67 or C-reactive protein, and mutational status of P53, KRAS, or BRCA2 are the most useful biomarkers in clinical practice. In addition to these, recent translational research has provided evidence of new biomarkers based on different molecules involved in endoplasmic reticulum stress, epithelial-to-mesenchymal transition, and noncoding RNA panels, especially microRNAs and long noncoding RNAs. These new prospects open new paths to tumour detection using minimally or noninvasive techniques such as liquid biopsies. To find sensitive and specific biomarkers to manage these patients constitutes a challenge for the research community and for public health policies.

Overexpression of p42.3 promotes cell proliferation, migration, and invasion in human gastric cancer cells

As a newly discovered tumor-specific gene, p42.3 is overexpressed in most of human gastric cancers (GC). However, the role of p42.3 in GC progression remains unclear. To assess the role of p42.3 in gastric cancers, immunohistochemistry and western blot were performed to detect the p42.3 expression in human GC tissues and cells. We also investigated the role of p42.3 in GC cell proliferation, migration, and invasion. Our results showed that the p42.3 expression was increased dramatically in human GC tissue and cells. In addition, we found that overexpression of p42.3 promotes GC cell proliferation, migration, and invasion abilities. Furthermore, p42.3 expression suppressed the E-cadherin protein level and promoted the β-catenin and p-ERK protein level. Taken together, overexpressed p42.3 is correlated with gastric cancer cell proliferation, migration, and invasion, suggesting its use as a biological marker in gastric cancer.

Key players in pancreatic cancer-stroma interaction: Cancer-associated fibroblasts, endothelial and inflammatory cells

Pancreatic cancer (PC) is the most aggressive type of common cancers, and in 2014, nearly 40000 patients died from the disease in the United States. Pancreatic ductal adenocarcinoma, which accounts for the majority of PC cases, is characterized by an intense stromal desmoplastic reaction surrounding the cancer cells. Cancer-associated fibroblasts (CAFs) are the main effector cells in the desmoplastic reaction, and pancreatic stellate cells are the most important source of CAFs. However, other important components of the PC stroma are inflammatory cells and endothelial cells. The aim of this review is to describe the complex interplay between PC cells and the cellular and non-cellular components of the tumour stroma. Published data have indicated that the desmoplastic stroma protects PC cells against chemotherapy and radiation therapy and that it might promote the proliferation and migration of PC cells. However, in animal studies, experimental depletion of the desmoplastic stroma and CAFs has led to more aggressive cancers. Hence, the precise role of the tumour stroma in PC remains to be elucidated. However, it is likely that a context-dependent therapeutic modification, rather than pure depletion, of the PC stroma holds potential for the development of new treatment strategies for PC patients.

IL-8, a novel messenger to cross-link inflammation and tumor EMT via autocrine and paracrine pathways (Review)

The epithelial-mesenchymal transition (EMT) is a process through which epithelial cells trans-differentiate and acquire an aggressive mesenchymal phenotype. In tumor cells, EMT is a vital step of tumor progression and metastasis. Amid the increasing interest in tumor EMT, only a few studies focused on the soluble mediators secreted by tumor cells passing through this phenotypic switch. In this review, we focus on the essential role of interleukin-8 (IL-8) signaling for the acquisition and maintenance of tumor EMT via direct and indirect mechanisms. Besides the autocrine loop between IL-8 and tumor cells that have gone through EMT, IL-8 could potentiate adjacent epithelial tumor cells into a mesenchymal phenotype via a paracrine mode. Moreover, understanding the role of IL-8 in EMT will provide insight into the pathogenesis of tumor progression and may facilitate the development of an effective strategy for the prevention and treatment of metastatic cancer.

Long-term survival after curative resection for pancreatic ductal adenocarcinoma--Surgical treatment

INTRODUCTION

Recent reports have demonstrated improvement in the 5-years serviva with resecate ductal adenocarcinoma. The aim of study is to determinate the factor influencing long-term survival after DCP.

MATERIALS AND METHODS

We have critically reviewed a group of 85 patients how were admitted to our department with diagnosis of ductal adenocarcinoma of the head of pancreas between January 1974 and January 1998.

RESULTS

Patients were stratified according to stage using TNM classification; in stage I 31 patients with 5 T1aN0M0 disease, 11 patients with T1bN0M0 and 15 patients T2N0M0 disease. By contrast, in stage III 54 patients with 48 patients T2N1M0 and 6 patients with T3N1M0. Tumour size was recorded for 72 patients with a median of 3.8 cm. The R1 dissection was performed in 67 patients. The R2 resection was performed in 18 patients. In our series we verified and analysed the histopathologic features of 5 patients with 15-years survival (5.8%). The features regard age, male or female, tumours size, stage and positive lymph node resection.

DISCUSSION

We found a specifically subset of patients where the combination of prognostic factors, in particular, negative surgical margins R0, tumour size ≤ 30 mm and the absence of lymph node metastasis independently reduced the mortality indicating that earlier tumour detection and histologically curative resection are important factors contributing to long term survival and healing of ductal adenocarcinoma of the head of the pancreas.

Embigin is overexpressed in pancreatic ductal adenocarcinoma and regulates cell motility through epithelial to mesenchymal transition via the TGF-β pathway

Embigin is a member of the immunoglobulin superfamily and encodes a transmembrane glycoprotein. There have been reports of Embigin involvement in neuromuscular junction formation and plasticity; however, the molecular functions of Embigin in other organs are unknown. Our aim was to investigate the possible role of Embigin in pancreatic cancer. In pancreatic ductal adenocarcinoma tissues, Embigin expression was higher than that in normal pancreatic tissues. Immunohistochemical analysis revealed expression of Embigin in pancreatic cancer cells, as well as expression of monocarboxylate transporter 2 (MCT2) in cancer tissues. To gain further insight, we transfected BxPC-3 and HPAC pancreatic cancer cells with siRNA or shRNA targeting Embigin and observed reductions in cell proliferation, migration, invasion, wound healing, and reduced levels of matrix metalloproteinases-2 and -9. Silencing of Embigin increased intracellular L-lactate concentration by 1.5-fold and decreased MCT2 levels at the plasma membrane. Furthermore, Embigin silencing led to a reduced expression of PI3K, GSK3-β, and Snail/Slug. Upon treating BxPC-3 cells with transforming growth factor-β (TGF-β), we observed elevated expression of Snail/Slug, Embigin, and Vimentin; meanwhile, when treating cells with SB-216763, a GSK3-β inhibitor, we noted decreases in GSK3-β, Snail/Slug, and Embigin expression, suggesting that the TGF-β signaling cascade, comprising PI3K, GSK3-β, Snail/Slug, and Embigin signals, mediates epithelial to mesenchymal transition (EMT) in pancreatic cancer cells. These findings indicate the involvement of Embigin in EMT in pancreatic cancer progression and suggest Embigin as a putative target for the detection and/or treatment of pancreatic cancer.

The epithelial to mesenchymal transition in pancreatic cancer: A systematic review

BACKGROUND/OBJECTIVES

The present article summarizes and analyzes the current knowledge about the role of the epithelial to mesenchymal transition (EMT) in the systemic invasiveness of pancreatic cancer.

METHOD

An electronic search of PubMed/MEDLINE, EMBASE, and the Web of Science was used to identify relevant original articles and reviews.

RESULTS

The EMT represents a key step during normal embryogenesis. However, increasing evidence reveals its essential role in the local progression and metastasis of pancreatic cancer. Areas of interest are the cross-linking between cells undergoing the EMT and pancreatic cancer stem cells, and the correlation between the EMT and chemoresistance to standard therapies. During carcinogenesis, malignant pancreatic cells at the primary site acquire the ability to undergo the EMT, a transformation associated with increased mobility. The reverse process at secondary sites, the mesenchymal to epithelial transition (MET), has devastating consequences, allowing neoplastic epithelial cells to invade surrounding tissues and spread to distant sites. Consequences of the EMT are the loss of E-cadherin expression and the acquisition of mesenchymal markers including fibronectin or vimentin. Detailed knowledge of the molecular processes underlying the EMT has opened possibilities for new therapeutic agents. These include an EMT approach for patients with early cancers, to prevent invasion and dissemination, and anti-MET therapy for patients with established metastasis.

CONCLUSIONS

The current literature shows a strong correlation between the EMT and the systemic aggressiveness of pancreatic tumors. Individualized therapy, targeting the process of EMT and its cross-linking with cancer stem cells, may increase survival of patients with pancreatic cancer.

The combination of the expression of hexokinase 2 and pyruvate kinase M2 is a prognostic marker in patients with pancreatic cancer

Metabolism may determine the biologically malignant behavior of pancreatic cancer. To investigate the significance and prognostic value of cancer metabolism in cancer patients, we investigated the expression of two key enzymes in anaerobic glycolysis, hexokinase 2 (HK2) and pyruvate kinase isoenzyme type M2 (PKM2), in surgical specimens obtained from 36 patients who underwent curative resection of pancreatic ductal carcinoma. The hk2-glycolysis axis is a key system in the clinical imaging of tumors via positron emission tomography. Immunohistochemical staining for hk2 and pkm2 was performed and the data were statistically analyzed to evaluate their prognostic power. The expression of hk2 and pkm2 was associated with clinicopathological variables and patient prognosis, including overall survival, local recurrence-free survival and distant metastasis-free survival. Staining for hk2 was negative and positive in 42 and 58% of the patients, respectively, whereas staining for pkm2 was negative and positive in 56 and 44%, respectively; hk2-positive staining was correlated with progressive pathological tumor stage (pT3 vs. pT1 and pT2; P=0.017). In the univariate analysis, the positive expression of hk2 and pkm2, pathological stage (pT3 vs. pT1 and pT2) and nodal metastasis were significantly correlated with poor prognosis (P<0.03). In the multivariate analysis, pathological nodal metastasis was an independent prognostic factor for overall survival, whereas the positive expression of hk2 and pkm2 exhibited borderline significance (P=0.08 and 0.12, hazard ratio = 2.57 and 2.16, respectively). In addition, the combination of high expression of hk2 as well as pkm2 was found to be significant (P<0.05). These results suggested that the expression of hk2 and pkm2, particularly their combination, in surgical specimens obtained during curative resection, may predict an unfavorable clinical outcome in patients with pancreatic cancer.

Combining clinicopathological predictors and molecular biomarkers in the oncogenic K-RAS/Ki67/HIF-1α pathway to predict survival in resectable pancreatic cancer

BACKGROUND

The dismal prognosis of patients diagnosed with pancreatic cancer points to our limited arsenal of effective anticancer therapies. Oncogenic K-RAS hyperactivation is virtually universal in pancreatic cancer, that confers drug resistance, drives aggressive tumorigenesis and rapid metastasis. Pancreatic tumours are often marked by hypovascularity, increased hypoxia and ineffective drug delivery. Thus, biomarker discovery and developing innovative means of countervailing oncogenic K-RAS activation are urgently needed.

METHODS

Tumour specimens from 147 pancreatic cancer patients were analysed by immunohistochemical (IHC) staining and tissue microarray (TMA). Statistical correlations between selected biomarkers and clinicopathological predictors were examined to predict survival.

RESULTS

We find that heightened hypoxia response predicts poor clinical outcome in resectable pancreatic cancer. SIAH is a tumour-specific biomarker. The combination of five biomarkers (EGFR, phospho-ERK, SIAH, Ki67 and HIF-1α) and four clinicopathological predictors (tumour size, pathological grade, margin and lymph node status) predict patient survival post surgery in pancreatic cancer.

CONCLUSIONS

Combining five biomarkers in the K-RAS/Ki67/HIF-1α pathways with four clinicopathological predictors may assist to better predict survival in resectable pancreatic cancer.

Mesenchymal-like pancreatic cancer cells harbor specific genomic alterations more frequently than their epithelial-like counterparts

The aggressiveness of pancreatic cancer is associated with the acquisition of mesenchymal characteristics by a subset of pancreatic cancer cells. The factors driving the development of this subset are not well understood. In this study, we tested the hypothesis that acquisition of a mesenchymal phenotype occurs selectively in tumor cells that harbor specific enabling genetic alterations. We obtained whole-genome comparative genomic hybridization (CGH) measurements on pancreatic cancer cell lines that have either an epithelial-like (17 cell lines) or a mesenchymal-like (9 cell lines) phenotype in vitro. The total amounts of amplifications and deletions were equivalent between the epithelial and mesenchymal groups, but 20 genes showed a major difference between the groups in prevalence of alterations. All 20 alterations (18 deletions and 2 amplifications) were more prevalent in the mesenchymal group, confirming the advanced nature of this cellular subtype. CDKN2A was altered in more than 50% of both groups, but co-deletions in neighboring genes, and concomitant loss of gene expression, were more prevalent in the mesenchymal group, suggesting that the size of the loss around CDKN2A affects cell phenotype. Whole-genome CGH on 11 primary cancer tissues revealed that the 20 genes were altered at a higher prevalence (up to 55% of the cases for certain genes) than randomly selected sets of 20 genes, with the same direction of alteration as in the cell lines. These findings support the concept that specific genetic alterations enable phenotype plasticity and provide promising candidate genes for further research.

pERK, pAKT and p53 as tissue biomarkers in erlotinib-treated patients with advanced pancreatic cancer: a translational subgroup analysis from AIO-PK0104

Background

The role of pERK, pAKT and p53 as biomarkers in patients with advanced pancreatic cancer has not yet been defined.

Methods

Within the phase III study AIO-PK0104 281 patients with advanced pancreatic cancer received an erlotinib-based 1^st-line regimen. Archival tissue from 153 patients was available for central immunohistochemistry staining for pERK, pAKT and p53. Within a subgroup analysis, biomarker data were correlated with efficacy endpoints and skin rash using a Cox regression model.

Results

Fifty-five out of 153 patients were classified as pERK^low and 98 patients as pERK^high; median overall survival (OS) was 6.2 months and 5.7 months, respectively (HR 1.29, p = 0.16). When analysing pERK as continuous variable, the pERK score was significantly associated with OS (HR 1.06, 95% CI 1.0-1.12, p = 0.05). Twenty-one of 35 patients were pAKT^low and 14/35 pAKT^high with a corresponding median OS of 6.4 months and 6.8 months, respectively (HR 1.03, p = 0.93). Four out of 50 patients had a complete loss of p53 expression, 20 patients a regular expression and 26 patients had tumors with p53 overexpression. The p53 status had no impact on OS (p = 0.91); however, a significant improvement in progression-free survival (PFS) (6.0 vs 1.8 months, HR 0.24, p = 0.02) and a higher rate of skin rash (84% vs 25%, p = 0.02) was observed for patients with a regular p53 expression compared to patients with a complete loss of p53.

Conclusion

pERK expression may have an impact on OS in erlotinib-treated patients with advanced pancreatic cancer; p53 should be further investigated for its potential role as a predictive marker for PFS and skin rash.

Trial registration

NCT00440167 (registration date: February 22, 2007).

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-624) contains supplementary material, which is available to authorized users.

Chronic pancreatitis and pancreatic cancer demonstrate active epithelial-mesenchymal transition profile, regulated by miR-217-SIRT1 pathway

Epithelial-mesenchymal transition (EMT) is supposed to be an inflammation induced response which may take a central role in tumorigenesis. Since recent evidence indicates that microRNAs may be involved in EMT, the present study set out to reveal the miRNA which might regulate the EMT in CP (chronic pancreatitis) and PC (pancreatic cancer) and its potential mechanism. Firstly, we provided evidence that both CP and PC tissues demonstrated active EMT profile. Consistently, miR-217 was obviously down-regulated in CP, PC and TGF-β1 treated PC cells, while negatively correlated to its direct target SIRT1. Moreover, either ectopic expression of miR-217 or inhibition of SIRT1 remarkably induced mesenchymal to epithelial transition (MET) in TGF-β1 treated PC cells. On the contrary, miR-217 inhibitor promoted EMT in PC cells but not in SIRT-knockdown PC cells. Clinical information from a cohort of 54 PC patients demonstrated that down-regulated miR-217 was positively correlated with late tumor stage, lymphatic invasion, vascular infiltration and distant metastasis. These results suggest that the overexpressed TGF-β1 in inflammation triggers the deregulation of the miR-217-SIRT1 pathway and then promotes the EMT process, which might be involved in the tumorigenesis of PC. Additionally, miR-217 may function as a novel target and predictor for PC prevention and therapy.

Targeting tight junctions during epithelial to mesenchymal transition in human pancreatic cancer

Pancreatic cancer continues to be a leading cause of cancer-related death worldwide and there is an urgent need to develop novel diagnostic and therapeutic strategies to reduce the mortality of patients with this disease. In pancreatic cancer, some tight junction proteins, including claudins, are abnormally regulated and therefore are promising molecular targets for diagnosis, prognosis and therapy. Claudin-4 and -18 are overexpressed in human pancreatic cancer and its precursor lesions. Claudin-4 is a high affinity receptor of Clostridium perfringens enterotoxin (CPE). The cytotoxic effects of CPE and monoclonal antibodies against claudin-4 are useful as novel therapeutic tools for pancreatic cancer. Claudin-18 could be a putative marker and therapeutic target with prognostic implications for patients with pancreatic cancer. Claudin-1, -7, tricellulin and marvelD3 are involved in epithelial to mesenchymal transition (EMT) of pancreatic cancer cells and thus might be useful as biomarkers during disease. Protein kinase C is closely related to EMT of pancreatic cancer and regulates tight junctions of normal human pancreatic duct epithelial cells and the cancer cells. This review focuses on the regulation of tight junctions via protein kinase C during EMT in human pancreatic cancer for the purpose of developing new diagnostic and therapeutic modalities for pancreatic cancer.

Translational research in pancreatic ductal adenocarcinoma: current evidence and future concepts

Pancreatic ductal adenocarcinoma (PDA) is one of the major causes for cancer death worldwide. Treatment of metastatic disease remains challenging as only certain patients benefit from advances made with the intensified chemotherapy regimen folinic acid, irinotecan and oxaliplatin, the epidermal growth factor receptor inhibitor erlotinib or the recently FDA-approved nab-paclitaxel. Up to date, no established approach for prediction of treatment response or specific treatment allocation exists. Translational research was able to identify a number of potential biomarkers that might help to improve the dismal prognosis of PDA by facilitating upfront treatment allocation. This topic highlight is focused on current evidence on potential biomarkers for tumor biology, prognosis and prediction of treatment efficacy.

Epithelial-to-mesenchymal transition (EMT) in intraductal papillary mucinous neoplasm (IPMN) is associated with high tumor grade and adverse outcomes

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is generally associated with increased tumor aggressiveness and poor prognosis. We evaluated EMT characteristics in intraductal papillary mucinous neoplasm (IPMN) tumor specimens and their potential role as biomarkers for malignancy, metastasis, and adverse patient outcomes.

METHODS

IPMN surgical specimens were identified and reviewed by two gastrointestinal pathologists. Immunohistochemical analysis of E-cadherin, vimentin, and ZEB-1 was performed. Samples were linked to clinicopathologic and outcome data for these patients. Western blot test was used to evaluate ZEB-1 expression in IPMN samples; 846 human miRNAs were profiled, and EMT-related differentially expressed miRNAs were validated using quantitative real-time polymerase chain reaction.

RESULTS

Fifty-eight IPMN specimens and five normal pancreatic tissue samples were immunohistochemically stained and scored. E-cadherin expression was significantly lower in malignant versus low-grade IPMN (p < 0.05). Vimentin expression was increased in malignant IPMN tumor samples (p < 0.05). EMT was associated with increased lymph node metastasis and decreased survival of malignant IPMN patients (p < 0.05). ZEB-1, an imperative EMT regulator, was exclusively expressed by malignant IPMN tumors. miRNA hierarchical clustering demonstrated grouping of two main IPMN subgroups: low-grade IPMN versus high-grade IPMN and carcinoma. Twenty-four miRNAs were differentially expressed (14 up-regulated, 10 down-regulated). The EMT-regulatory miRNAs, miR-200c and miR-141, were down-regulated (twofold and 1.8-fold decrease, respectively) in malignant versus low-grade IPMN (p < 0.05).

CONCLUSIONS

EMT may play a role in IPMN tumorigenesis and metastasis. EMT molecular deregulations could be utilized as potential novel biomarkers for the identification of high-risk IPMN patients.

KAP-1 is overexpressed and correlates with increased metastatic ability and tumorigenicity in pancreatic cancer

This study aimed to investigate the role in metastasis and prognostic value of KAP-1 in pancreatic cancer (PC). The expression of KAP-1 was analyzed by quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemical staining in 91 human PC tissue samples. Capan-2 cells were transfected with a lentiviral vector expressing KAP-1 (Capan-2/KAP-1) or the empty vector (Capan-2/vector); cell migration and invasion were assayed in vitro using Transwell migration and wound-healing assays, and in vivo using a xenograft model in nude mice. KAP-1 was found to be overexpressed in human PC, and the expression of KAP-1 correlated with clinical stage. Overexpression of KAP-1 increased the invasion and migration of Capan-2 cells in vitro. Furthermore, overexpression of KAP-1 promoted the growth and metastatic ability of PC cells in a xenograft model in nude mice. Moreover, overexpression of KAP-1 induced the epithelial-mesenchymal transition (EMT) in PC cells both in vitro and in vivo, as indicated by increased expression of mesenchymal markers such as vimentin and decreased expression of E-cadherin. This study indicates that KAP-1 may promote metastasis in PC by regulating the EMT and suggests that KAP-1 may have potential as a predictor of metastasis in patients with pancreatic cancer.

Upregulated SMAD3 promotes epithelial-mesenchymal transition and predicts poor prognosis in pancreatic ductal adenocarcinoma

In pancreatic ductal adenocarcinoma (PDAC), features of epithelial-mesenchymal transition (EMT) are often seen in tumor tissue, and such features correlate with poor prognosis. Solitary infiltration of tumor cells represents a morphological phenotype of EMT, and we previously reported that a high degree of solitary cell infiltration correlates with EMT-like features, including reduced E-cadherin and elevated vimentin levels. Using solitary cell infiltration to evaluate the degree of EMT, gene-expression profiling of 12 PDAC xenografts was performed, and SMAD3 was identified as an EMT-related gene. Immunohistochemistry using clinical specimens (n=113) showed that SMAD3 accumulated in the nuclei of tumor cells, but was not detected in most epithelial cells in the pancreatic duct. Moreover, SMAD3 upregulation correlated with malignant characteristics, such as higher tumor grade and lymph node metastasis, as well as with EMT-like features. SMAD4, which plays a key role in transforming growth factor-β (TGF-β) signaling, is inactivated in approximately half of PDAC cases. In this study, the nuclear accumulation of SMAD3 was immunohistochemically detected even in SMAD4-negative cases. SMAD3 knockdown resulted in upregulated E-cadherin, downregulated vimentin, and reduced cell motility in pancreatic cancer cells regardless of SMAD4 status. In addition, TGF-β-treatment resulted in EMT induction in cells carrying wild-type SMAD4, and EMT was suppressed by SMAD3 knockdown. Patients with upregulated SMAD3 and a high degree of solitary cell infiltration had shorter times to recurrence and shorter survival times after surgery, and multivariate analysis showed that both factors were independent prognostic factors linked to unfavorable outcomes. These findings suggest that SMAD3 in PDAC is involved in the promotion of malignant potential through EMT induction in tumor cells regardless of SMAD4 status and serves as a potential biomarker of poor prognosis.

Oncofetal H19 RNA promotes tumor metastasis

The oncofetal H19 gene transcribes a long non-coding RNA(lncRNA) that is essential for tumor growth. Here we found that numerous established inducers of epithelial to mesenchymal transition(EMT) also induced H19/miR-675 expression. Both TGF-β and hypoxia concomitantly induced H19 and miR-675 with the induction of EMT markers. We identified the PI3K/AKT pathway mediating the inductions of Slug, H19 RNA and miR-675 in response to TGF-β treatment, while Slug induction depended on H19 RNA. In the EMT induced multidrug resistance model, H19 level was also induced. In a mouse breast cancer model, H19 expression was tightly correlated with metastatic potential. In patients, we detected high H19 expression in all common metastatic sites tested, regardless of tumor primary origin. H19 RNA suppressed the expression of E-cadherin protein. H19 up-regulated Slug expression concomitant with the suppression of E-cadherin protein through a mechanism that involved miR-675. Slug also up-regulated H19 expression and activated its promoter. Altogether, these results may support the existence of a positive feedback loop between Slug and H19/miR-675, that regulates E-cadherin expression. H19 RNA enhanced the invasive potential of cancer cells in vitro and enhanced tumor metastasis in vivo. Additionally, H19 knockdown attenuated the scattering and tumorigenic effects of HGF/SF. Our results present novel mechanistic insights into a critical role for H19 RNA in tumor progression and indicate a previously unknown link between H19/miR-675, Slug and E-cadherin in the regulation of cancer cell EMT programs.

CD24 and S100A4 expression in resectable pancreatic cancers with earlier disease recurrence and poor survival

OBJECTIVES

The objectives of this study were to study the expression status of markers associated with epithelial-to-mesenchymal transition (EMT) and metastasis in pancreatic ductal adenocarcinomas (PDACs) and to explore the prognostic value of these markers.

METHODS

Immunohistochemical stains for CD24, CD44, E-cadherin, N-cadherin, Snail, S100A4, Vimentin, urokinase-type plasminogen activator receptor, Ezrin, and matrix metalloproteinase 2 were performed on 67 resected PDACs.

RESULTS

Proteins associated with EMT and metastasis were more frequently expressed in PDACs with poor differentiation, higher tumor stage, and lymphatic and perineural invasion. CD24 expression was associated with frequent expression of EMT markers (CD44 [P = 0.004], S100A4 [P < 0.001], Vimentin [P = 0.022], urokinase-type plasminogen activator receptor [P = 0.002], and Ezrin [P = 0.010]). CD24 and S100A4 expressions in PDAC were significant prognostic factors for early tumor recurrence (hazard risk [HR], 5.185 and 2.490, P = 0.048 and 0.009, respectively) and poor survival (HR, 11.977 and 3.202, P = 0.006 and 0.004, respectively). In addition, the interaction between CD24 and S100A4 expression status was a significant prognostic factor for poor survival (HR, 18.518, P = 0.003).

CONCLUSIONS

The expression of markers of EMT and metastasis in PDACs was significantly associated with pathologic features of aggressiveness. CD24 and S100A4 expressions were significant predictors of poor survival; thus, immunohistochemistry for these markers in resected specimens may help to identify PDAC patients with a poor prognosis.

Excess PLAC8 promotes an unconventional ERK2-dependent EMT in colon cancer

The epithelial-to-mesenchymal transition (EMT) transcriptional program is characterized by repression of E-cadherin (CDH1) and induction of N-cadherin (CDH2), and mesenchymal genes like vimentin (VIM). Placenta-specific 8 (PLAC8) has been implicated in colon cancer; however, how PLAC8 contributes to disease is unknown, and endogenous PLAC8 protein has not been studied. We analyzed zebrafish and human tissues and found that endogenous PLAC8 localizes to the apical domain of differentiated intestinal epithelium. Colon cancer cells with elevated PLAC8 levels exhibited EMT features, including increased expression of VIM and zinc finger E-box binding homeobox 1 (ZEB1), aberrant cell motility, and increased invasiveness. In contrast to classical EMT, PLAC8 overexpression reduced cell surface CDH1 and upregulated P-cadherin (CDH3) without affecting CDH2 expression. PLAC8-induced EMT was linked to increased phosphorylated ERK2 (p-ERK2), and ERK2 knockdown restored cell surface CDH1 and suppressed CDH3, VIM, and ZEB1 upregulation. In vitro, PLAC8 directly bound and inactivated the ERK2 phosphatase DUSP6, thereby increasing p-ERK2. In a murine xenograft model, knockdown of endogenous PLAC8 in colon cancer cells resulted in smaller tumors, reduced local invasion, and decreased p-ERK2. Using MultiOmyx, a multiplex immunofluorescence-based methodology, we observed coexpression of cytosolic PLAC8, CDH3, and VIM at the leading edge of a human colorectal tumor, supporting a role for PLAC8 in cancer invasion in vivo.

CD133 facilitates epithelial-mesenchymal transition through interaction with the ERK pathway in pancreatic cancer metastasis

BACKGROUND

Pancreatic cancer is a lethal disease due to the high incidence of metastasis at the time of detection. CD133 expression in clinical pancreatic cancer correlates with poor prognosis and metastasis. However, the molecular mechanism of CD133-regulated metastasis remains unclear. In recent years, epithelial-mesenchymal transition (EMT) has been linked to cancer invasion and metastasis. In the present study we investigated the role of CD133 in pancreatic cancer metastasis and its potential regulatory network.

METHODS

A highly migratory pancreatic cancer cell line, Capan1M9, was established previously. After shRNA was stable transducted to knock down CD133 in Capan1M9 cells, gene expression was profiled by DNA microarray. Orthotopic, splenic and intravenous transplantation mouse models were set up to examine the tumorigenesis and metastatic capabilities of these cells. In further experiments, real-time RT-PCR, Western blot and co-immunoprecipitate were conducted to evaluate the interactions of CD133, Slug, N-cadherin, ERK1/2 and SRC.

RESULTS

We found that CD133+ human pancreatic cancer cells were prone to generating metastatic nodules in in vivo models using immunodeficient mice. In contrast, CD133 knockdown suppressed cancer invasion and metastasis in vivo. Gene profiling analysis suggested that CD133 modulated mesenchymal characteristics including the expression of EMT-related genes, such as Slug and N-cadherin. These genes were down-regulated following CD133 knockdown. Moreover, CD133 expression could be modulated by the extracellular signal-regulated kinase (ERK)1/2 and SRC signaling pathways. The binding of CD133 to ERK1/2 and SRC acts as an indispensable mediator of N-cadherin expression.

CONCLUSIONS

These results demonstrate that CD133 plays a critical role in facilitating the EMT regulatory loop, specifically by upregulating N-cadherin expression, leading to the invasion and metastasis of pancreatic cancer cells. Our study provides a novel insight into the function of CD133 in the EMT program and a better understanding of the mechanism underlying the involvement of CD133 in pancreatic cancer metastasis.

Epithelial-to-mesenchymal transition predicts prognosis of pancreatic cancer

BACKGROUND

Pancreatic cancer has a dismal prognosis that is attributed to common local invasiveness and metastasis. Epithelial-to-mesenchymal transition (EMT) plays an important role in cancer invasion and metastasis and is associated with early dissemination. The aim of this study was to evaluate the association between EMT and the prognoses for patients with pancreatic cancer.

METHODS

Immunohistochemistry of E-cadherin and vimentin was performed on surgical specimens from 174 patients who underwent resection of their pancreatic cancers. Tumoral stainings of E-cadherin and vimentin were graded, and EMT statuses were determined by calculating the ratio of vimentin to E-cadherin, whereby patients were categorized into 3 groups: epithelial, intermediate, and mesenchymal. The correlations between EMT statuses and clinicopathologic factors and prognoses were analyzed.

RESULTS

There was a significant correlation between EMT status and CA19-9 levels (P = .020); peritoneal washing cytology (P = .025); portal vein invasion (P = .038); and lymph node metastasis (P = .030). The median survival for patients with epithelial tumors was 40.2 months as compared to 13.7 months for patients with mesenchymal tumors. Multivariate analysis demonstrated that perineural invasion (P = .024); lymph node metastasis (P = .033); and EMT status (P < .0001) were significant prognostic factors. It is interesting that adjuvant chemotherapy (gemcitabine and/or S-1) improved the median survival time from 10.8 to 16.1 months in patients with mesenchymal tumors (P = .002); however, no significant difference was seen in patients with epithelial tumors.

CONCLUSION

EMT status is an important prognostic factor for pancreatic cancer and is associated with portal vein invasion and lymph node metastasis.

Targeting cancer-related inflammation: Chinese herbal medicine inhibits epithelial-to-mesenchymal transition in pancreatic cancer

Pancreatic cancer is an almost universally fatal disease resulting from early invasion of adjacent structures and metastasis and the lack of an effective treatment modality. Our previous studies have shown that Qingyihuaji Formula (QYHJ), a seven-herb Chinese medicine formula, had significant anti-cancer effects in pancreatic cancer. Here, we examined the effects of QYHJ on pancreatic cancer cell invasion and metastasis and the potential associated mechanism(s). We found that QYHJ inhibited both tumor growth and metastasis in nude mice with human pancreatic cancer cell xenografts. Further study indicated that QYHJ inhibited epithelial-to-mesenchymal transition (EMT), which is characterized by increased E-cadherin expression and decreased vimentin, N-cadherin and Slug expression. Interleukin 6 (IL-6), a pro-inflammatory cytokine produced mainly by macrophages, could promote cancer cell EMT and invasion. In contrast, treatment with QYHJ inhibited cancer-related inflammation in tumors by decreasing infiltration of tumor-associated macrophages and IL-6 production, thus preventing cell invasion and metastasis. These results suggested that the Chinese herbal medicine QYHJ could inhibit pancreatic cancer cell invasion and metastasis in part by reversing tumor-supporting inflammation.

M2-polarized tumor-associated macrophages promoted epithelial-mesenchymal transition in pancreatic cancer cells, partially through TLR4/IL-10 signaling pathway

M2-polarized tumor-associated macrophages (TAMs) are key regulators of the link between inflammation and cancer. A negative correlation between infiltration intensity of M2-polarized TAMs and prognosis of pancreatic cancer has been reported. Epithelial-mesenchymal transition (EMT) is an important biological process in the progression of primary tumors toward metastasis. Inflammation-induced EMT has been previously shown, therefore, we hypothesized M2-polarized TAMs could induce EMT in pancreatic cancer. Toll-like receptor 4 (TLR4) signaling has an active role in tumor progression during chronic inflammation and the receptor is primarily expressed on macrophages. Activation of TLR4 on M2-polarized TAMs stimulates an increase in the cytokine interleukin-10 (IL-10); consequently, another aim was to investigate the potential role of TLR4/IL-10 signaling in the EMT of pancreatic cancer. Treatment with IL-4 (20 ng/ml) for 24 h successfully induced the polarization of macrophage cell line RAW 264.7 to M2 phenotype, IL-10(high), IL-12(low), and IL-23(low), and high expression of CD204 and CD206. A coculture system allowed investigation of the roles of M2-polarized TAMs and TLR4/IL-10 signaling in the EMT of Panc-1 and BxPC-3 pancreatic cancer cell lines. Our results showed that coculture with M2-polarized TAMs increased fibroblastic morphology, upregulated mesenchymal markers vimentin and snail at the mRNA and protein levels, and increased proliferation, migration, and metalloproteinase (MMP)2 and MMP9 proteolytic activity in pancreatic cancer cells. Simultaneously, coculture with M2-polarized TAMs decreased the expression of the epithelial marker E-cadherin. Coculture with pancreatic cancer cells increased TLR4 mRNA and protein expression in M2-polarized TAMs. Application of TLR4 siRNA and neutralizing antibodies against TLR4 and IL-10 markedly inhibited E-cadherin reduction and the upregulation of snail and vimentin. Furthermore, activation of TLR4 signaling by lipopolysaccharide profoundly increased the EMT of pancreatic cancer cells. In conclusion, M2-polarized TAMs promoted EMT in pancreatic cancer cells partially through TLR4/IL-10 signaling, suggesting novel therapeutic strategies and enhancing our understanding of M2-polarized TAMs.

Persistent activation of pancreatic stellate cells creates a microenvironment favorable for the malignant behavior of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumors with poor prognosis due to extremely high malignancy, low rate of eligibility for surgical resection and chemoradiation resistance. Increasing evidence indicate that the interaction between activated pancreatic stellate cells (PSCs) and PDAC cells plays an important role in the development of PDAC. By producing high levels of cytokines, chemotactic factors, growth factors and excessive extracellular matrix (ECM), PSCs create desmoplasia and a hypoxic microenvironment that promote the initiation, development, evasion of immune surveillance, invasion, metastasis and resistance to chemoradiation of PDAC. Therefore, targeting the interaction between PSCs and PDAC cells may represent a novel therapeutic approach to advanced PDAC, especially therapies that target PSCs of the pancreatic tumor microenvironment.

Molecular biology of adenocarcinoma of the pancreatic duct, current state and future therapeutic avenues

Pancreatic adenocarcinoma is a lethal disease; currently surgery offers five years survival of less than 5%. Any improvement in the outcome is likely to be through novel therapeutic agents that will target the genetic machinery of the cell. Knowledge of genetic alterations in the process of carcinogenesis is expanding rapidly, the targeted therapy, however, is progressing slowly. Pancreatic adenocarcinoma displays a variety of molecular changes that evolve exponentially with time and lend the cancer cells their ability not only to survive, but also to invade the surrounding tissues and metastasise to distant sites. These changes involve genetic alteration in oncogenes, cancer suppressor genes, changes in cell cycle, pathways of apoptosis and also changes in epithelial to mesenchymal transition. Monotherapeutic targeted agents seem(s) to have limited effect on cancer cells. The near future is likely to show an improvement in the treatment outcome, which is likely to be a result of the combination of targeted agents with surgery and chemotherapy.

Epithelial-mesenchymal transition and its role in the pathogenesis of colorectal cancer

Epithelial-to-mesenchymal transition (EMT) is a collection of events that allows the conversion of adherent epithelial cells, tightly bound to each other within an organized tissue, into independent fibroblastic cells possessing migratory properties and the ability to invade the extracellular matrix. EMT contributes to the complex architecture of the embryo by permitting the progression of embryogenesis from a simple single-cell layer epithelium to a complex three-dimensional organism composed of both epithelial and mesenchymal cells. However, in most tissues EMT is a developmentally restricted process and fully differentiated epithelia typically maintain their epithelial phenotype. Recently, elements of EMT, specially the loss of epithelial markers and the gain of mesenchymal markers, have been observed in pathological states, including epithelial cancers. Increasing evidence has confirmed its presence in human colon during colorectal carcinogenesis. In general, chronic inflammation is considered to be one of the causes of many human cancers including colorectal cancer(CRC). Accordingly, epidemiologic and clinical studies indicate that patients affected by ulcerative colitis and Crohn's disease, the two major forms of inflammatory bowel disease, have an increased risk of developing CRC. A large body of evidence supports roles for the SMAD/STAT3 signaling pathway, the NF-kB pathway, the Ras-mitogen- activated protein kinase/Snail/Slug and microRNAs in the development of colorectal cancers via epithelial-to- mesenchymal transition. Thus, EMT appears to be closely involved in the pathogenesis of colorectal cancer, and analysis refered to it can yield novel targets for therapy.

Epithelial-to-mesenchymal transition in pancreatic ductal adenocarcinoma and pancreatic tumor cell lines: the role of neutrophils and neutrophil-derived elastase

Pancreatic ductal adenocarcinoma (PDAC) is frequently associated with fibrosis and a prominent inflammatory infiltrate in the desmoplastic stroma. Moreover, in PDAC, an epithelial-to-mesenchymal transition (EMT) is observed. To explore a possible connection between the infiltrating cells, particularly the polymorphonuclear neutrophils (PMN) and the tumor cell transition, biopsies of patients with PDAC (n = 115) were analysed with regard to PMN infiltration and nuclear expression of β-catenin and of ZEB1, well-established indicators of EMT. In biopsies with a dense PMN infiltrate, a nuclear accumulation of β-catenin and of ZEB1 was observed. To address the question whether PMN could induce EMT, they were isolated from healthy donors and were cocultivated with pancreatic tumor cells grown as monolayers. Rapid dyshesion of the tumor cells was seen, most likely due to an elastase-mediated degradation of E-cadherin. In parallel, the transcription factor TWIST was upregulated, β-catenin translocated into the nucleus, ZEB1 appeared in the nucleus, and keratins were downregulated. EMT was also induced when the tumor cells were grown under conditions preventing attachment to the culture plates. Here, also in the absence of elastase, E-cadherin was downmodulated. PMN as well as prevention of adhesion induced EMT also in liver cancer cell line. In conclusion, PMN via elastase induce EMT in vitro, most likely due to the loss of cell-to-cell contact. Because in pancreatic cancers the transition to a mesenchymal phenotype coincides with the PMN infiltrate, a contribution of the inflammatory response to the induction of EMT and—by implication—to tumor progression is possible.

Molecular pathology of pancreatic cancer: from bench-to-bedside translation

Pancreatic ductal adenocarcinoma (referred here as pancreatic cancer) is a lethal disease with the worst prognosis among all solid tumors. Surgical resection represents the only hope for cure but it is possible only in patients that present with local disease (about 20% of cases). Whether dismal prognosis of pancreatic cancer is a result of late diagnosis or early dissemination to distant organ is still a debate. Moreover, this disease shows an intrinsic chemotherapeutic resistance that has been mainly ascribed to the presence of a dense stromal reaction that significantly impairs drugs delivery. Clinical management of pancreatic cancer patients relies on few molecular markers (e.g., the diagnostic marker CA19-9) that, however, present several limitations to their use. The clinical usefulness of somatic alterations in well-characterized genes (such as KRAS and TP53), whose detection is technically feasible in different biological samples, has been extensively investigated leading to inconsistent results. Furthermore, none of the candidate molecular markers identified in recent years has shown an appropriate clinical performance and therefore none is routinely used. This depicts a scenario where the identification of novel and effective clinical biomarkers is mandatory. Very recent genome-wide comprehensive studies have shed light on the high degree of genetic complexity and heterogeneity of the pancreatic cancers. Although far from being introduced into the clinical settings, results from those studies are expected to change definitively the perspective through which we look at the clinical management of pancreatic cancer patients towards a personalized cancer medicine.

Cdk4/6 inhibition induces epithelial-mesenchymal transition and enhances invasiveness in pancreatic cancer cells

Aberrant activation of Cyclin D-Cdk4/6 signaling pathway is commonly found in pancreatic ductal adenocarcinoma (PDAC). Here, we show that PD-0332991, a highly specific inhibitor for Cdk4 and Cdk6, exerted growth inhibitory effects on three human PDAC cell lines. Microarray analysis revealed that PD-0332991 downregulated cell-cycle-related genes, but upregulated genes implicated in extracellular matrix (ECM) remodeling and pancreatic cancer cell invasion and metastasis. Moreover, PD-0332991 enhanced invasion in TGF-β-responsive PDAC cell lines that harbor a wild-type SMAD4 gene (COLO-357, PANC-1), but not in TGF-β-resistant AsPC-1 cells that harbor a mutated SMAD4. PD-0332991 also induced epithelial-mesenchymal transition (EMT) in COLO-357 and PANC-1, but not in AsPC-1 cells. Inhibition of CDK4/6 using shRNA mimicked the effects of PD-0332991 on EMT induction. Furthermore, PD-0332991 increased Smad transcriptional activity in luciferase readout assays and activated TGF-β signaling. SB-505124, an inhibitor of the type-I TGF-β receptor (TβRI) kinase, completely blocked EMT induction by PD-0332991. When combined with PD-0332991, SB-505124 inhibited the growth of COLO-357 and PANC-1 cells. Taken together, these data suggest that anti-Cdk4/6 therapy could induce EMT and enhance pancreatic cancer cell invasion by activating Smad-dependent TGF-β signaling, and that combining PD-0332991 and SB-505124 may represent a novel therapeutic strategy in PDAC.

Deguelin suppresses pancreatic tumor growth and metastasis by inhibiting epithelial-to-mesenchymal transition in an orthotopic model

Deguelin is known to suppress the growth of cancer cells; however, its anti-metastatic effects have not been studied so far in any cancer model. In the present study, we aimed to evaluate the anti-metastatic potential of deguelin in vivo and in tumor growth factor-β1 (TGFβ1)-stimulated cells. Our results demonstrate that tumor growth, peritoneal dissemination and liver/lung metastasis of orthotopically implanted PanC-1-luc cells were significantly reduced in deguelin-treated mice along with the induction of apoptosis. Furthermore, deguelin-treated tumors showed increased epithelial signature such as increased expression of E-Cadherin and cytokeratin-18 and decreased expression of Snail. Similar observations were made when PanC-1, COLO-357 and L3.6pl cells were treated in vitro with deguelin. Moreover, E-cadherin was transcriptionally upregulated and accumulated in the membrane fraction of deguelin-treated cells, as indicated by increased interaction of E-Cadherin with β-catenin. TGFβ1-induced downregulation of E-Cadherin and upregulation of Snail were abrogated by deguelin treatment. In addition, deguelin inhibited TGFβ1-induced Smad3 phosphorylation and Smad4 nuclear translocation in PanC-1 cells. Furthermore, when TGFβ1-induced nuclear factor kappa B (NFκB) activation was inhibited, TGFβ1-induced Snail upregulation or E-Cadherin downregulation was blocked. Deguelin also significantly downregulated the constitutive phosphorylation and DNA binding of NFκB in a dose-dependent manner. Interestingly, overexpression of either NFκB or Snail completely abrogated deguelin-mediated epithelial-to-mesenchymal transition (EMT) inhibition, whereas overexpression of NFκB but not Snail rescued cells from deguelin-induced apoptosis. Hence, deguelin targets NFκB to induce reversal of EMT and apoptosis but downstream effectors might be different for both processes. Taken together, our results suggest that deguelin suppresses both pancreatic tumor growth and metastasis by inducing apoptosis and inhibiting EMT.

The role of epithelial-mesenchymal transition in pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer related death in the US. Despite the advances in medical and surgical treatment, the 5-year survival rate for such cancer is only approximately 5% when considering all stages of disease. The lethal nature of pancreatic cancer stems from its high metastatic potential to the lymphatic system and distant organs. Lack of effective chemotherapies, which is believed to be due to drug-resistance, also contributes to the high mortality of pancreatic cancer. Recent evidence suggests that epithelial-mesenchymal transition of pancreatic cancer cells contributes to the development of drug resistance and an increase in invasiveness. Future strategies that specifically target against epithelial-mesenchymal transition phenotype could potentially reduce tumoral drug resistance and invasiveness and hence prolong the survival of patients with pancreatic cancer.

Aerosol delivery of kinase-deficient Akt1 attenuates Clara cell injury induced by naphthalene in the lungs of dual luciferase mice

Conventional lung cancer therapies are associated with poor survival rates; therefore, new approaches such as gene therapy are required for treating cancer. Gene therapies for treating lung cancer patients can involve several approaches. Among these, aerosol gene delivery is a potentially more effective approach. In this study, Akt1 kinase-deficient (KD) and wild-type (WT) Akt1 were delivered to the lungs of CMV-LucR-cMyc-IRES-LucF dual reporter mice through a nose only inhalation system using glucosylated polyethylenimine and naphthalene was administrated to the mice via intraperitoneal injection. Aerosol delivery of Akt1 WT and naphthalene treatment increased protein levels of downstream substrates of Akt signaling pathway while aerosol delivery of Akt1 KD did not. Our results showed that naphthalene affected extracellular signal-regulated kinase (ERK) protein levels, ERK-related signaling, and induced Clara cell injury. However, Clara cell injury induced by naphthalene was considerably attenuated in mice exposed to Akt1 KD. Furthermore, a dual luciferase activity assay showed that aerosol delivery of Akt1 WT and naphthalene treatment enhanced cap-dependent protein translation, while reduced cap-dependent protein translation was observed after delivering Akt1 KD. These studies demonstrated that our aerosol delivery is compatible for in vivo gene delivery.

Pancreatic ductal adenocarcinoma: long-term survival does not equal cure

BACKGROUND

Pancreatic ductal adenocarcinoma represents 90% of pancreatic cancers and is an important cause of cancer death in the United States. Operative resection remains as the only treatment providing prolonged survival, but even after a curative resection, 5-year survival rates are low. Our aim was to identify the prognostic factors for long-term survival after resection of pancreatic ductal adenocarcinoma related to patients, treatments, and tumor biology.

METHODS

Retrospective review identified 959 patients who underwent resection of their pancreatic adenocarcinoma between February 1985 and December 2010, of whom 499 were resected before November 2006 and represent the cohort we describe in this study. Patient, tumor, and treatment-related variables were assessed for their associations with 5- and 10-year overall survival.

RESULTS

Of the 499 patients, 49% were female and median age was 65 years. The majority of patients had stage IIb disease (60%). Actual 5-year survival after resection of pancreatic adenocarcinoma was 19% (95/499), and actual 10-year survival was 10% (33/329). Significant clinicopathologic factors predicting 5- and 10-year survival were negative margins and negative nodal status. Interestingly, 41% (39/95) of long-term survivors had positive nodes and 24% (23/95) had positive margins.

CONCLUSION

Pancreatic ductal adenocarcinoma demonstrates a very heterogeneous biology, but patients with negative resection margins and node negative cancers are more likely to survive 5 years after resection. However, our series demonstrates that the biology of the cancer rather than simple pathologic factors determine a patient's prognosis.

Stroma and pancreatic ductal adenocarcinoma: an interaction loop

Pancreatic ductal adenocarcinoma (PDA) has two exceptional features. First, it is a highly lethal disease, with a median survival of less than 6 months and a 5-year survival rate less than 5%. Second, PDA tumor cells are surrounded by an extensive stroma, which accounts for up to 90% of the tumor volume. It is well recognized that stromal microenvironment can accelerate malignant transformation, tumor growth and progression. More importantly, the interaction loop between PDA and its stroma greatly contributes to tumor growth and progression. We propose that the extensive stroma of PDA is closely linked to its poor prognosis. An improved understanding of the mechanisms that contribute to pancreatic tumor growth and progression is therefore urgently needed. Targeting the stroma may thus provide novel prevention, earlier detection and therapeutic options to this deadly malignancy. Accordingly, in this review, we will summarize the mechanism of PDA stroma formation, the role of the stroma in tumor progression and therapy resistance and the potential of stroma-targeted therapeutics strategies.

Biological and prognostic relevance of mitogen-activated protein kinases in pancreatic adenocarcinoma

OBJECTIVES

The aims of this study were to study the biological and clinical significance of 3 main proteins of the mitogen-activated protein kinase (MAPK) signaling pathway, ERK1/2, P38, and MKK4, in a series of patients having pancreatic adenocarcinomas treated by surgery.

METHODS

We examined the immunohistochemical expression of 3 MAPK proteins, ERK1/2, P38, and MKK4 in 99 surgically resected pancreatic ductal adenocarcinomas. Tumor protein expression was studied with regard to pathological characteristics and to postsurgical recurrence-free and overall survivals.

RESULTS

MKK4 expression was related to tumor cell proliferation, evaluated by the Ki67 index (P < 0.01). ERK1/2 expression was related to a shorter recurrence-free survival on both univariate and multivariate analysis (P < 0.01; odds ratio, 8.39; 95% confidence interval, 2.68-26.26) independently of lymph node metastases and tumor size, and to a shorter overall survival (P = 0.01) on univariate analysis. In patients without postsurgical treatment, both ERK1/2 and P38 tumor expression correlated with a shorter recurrence-free survival (P < 0.01 and P = 0.02, respectively).

CONCLUSIONS

The results of our study suggest that in pancreatic ductal adenocarcinomas, the MKK4 protein was directly related to high cell proliferation, and that tumor ERK1/2 and P38 expression correlated to shorter postsurgical recurrence-free and overall survivals.

Pancreatic cancer stem cells: emerging target for designing novel therapy

In the past few years, there have been significant advances in the research on cancer stem cells (CSCs). The emerging evidences have demonstrated that CSCs and epithelial-mesenchymal transition (EMT)-type cells, which share molecular characteristics with CSCs, play critical roles in drug resistance, invasion, and metastasis. Pancreatic cancer (PC) has a high mortality due to both intrinsic (de novo) and extrinsic (acquired) drug resistance, leading to increased invasive and metastatic potential of PC cells. Therefore, targeting pancreatic CSCs and EMT-type cells could be a novel therapeutic strategy for the treatment of PC. In this article, we will review the current state of our knowledge on the role of pancreatic CSCs and EMT-type cells, and summarize the novel therapeutic strategies that could target pancreatic CSCs and EMT-type cells, leading to the reversal of EMT phenotype, the induction of drug sensitivity, and the inhibition of invasion and metastasis of PC, which is expected to yield better treatment outcome.

ERK/GSK3β/Snail signaling mediates radiation-induced alveolar epithelial-to-mesenchymal transition

Radiotherapy is one of the major treatment regimes for thoracic malignancies, but can lead to severe lung complications including pneumonitis and fibrosis. Recent studies suggest that epithelial-to-mesenchymal transition (EMT) plays an important role in tissue injury leading to organ fibrosis. To investigate whether radiation can induce EMT in lung epithelial cells and also to understand the potential mechanism(s) associated with this change, rat alveolar type II lung epithelial RLE-6TN cells were irradiated with 8 Gy of (137)Cs γ-rays. Western blot and immunofluorescence analyses revealed a time-dependent decrease in E-cadherin with a concomitant increase in α-smooth muscle actin (α-SMA) and vimentin after radiation, suggesting that the epithelial cells acquired a mesenchymal-like morphology. Protein levels and nuclear translocation of Snail, the key inducer of EMT, were significantly elevated in the irradiated cells. Radiation also induced a time-dependent inactivation of glycogen synthase kinase-3β (GSK3β), an endogenous inhibitor of Snail. A marked increase in phosphorylation of ERK1/2, but not JNK or p38, was observed in irradiated RLE-6TN cells. Silencing ERK1/2 using siRNAs and the MEK/ERK inhibitor U0126 attenuated the radiation-induced phosphorylation of GSK3β and altered the protein levels of Snail, α-SMA, and E-cadherin in RLE-6TN cells. Preincubating RLE-6TN cells with N-acetylcysteine, an antioxidant, abolished the radiation-induced phosphorylation of ERK and altered protein levels of Snail, E-cadherin, and α-SMA. These findings reveal, for the first time, that radiation-induced EMT in alveolar type II epithelial cells is mediated by the ERK/GSK3β/Snail pathway.

Genomics and pharmacogenomics of pancreatic adenocarcinoma

The last decade has brought significant advances in the development of molecularly targeted therapies for treatment of a variety of human malignancies. In contrast to other solid tumors, however, the impact of novel therapeutic strategies on clinical outcomes in patients with pancreas adenocarcinoma (PAC) has been limited to date. Gemcitabine was established as a standard of care for treatment of advanced PAC in 1997 based on an observed improvement in clinical benefit as adjudicated principally by pain scores and analgesic consumption, and demonstration of an overall survival (OS) benefit in a randomized comparison with 5-fluorouracil (5-FU). Since then, multiple agents targeting oncogenic signaling pathways and mediators of angiogenesis have failed to improve outcomes in phase III clinical trials when compared with gemcitabine monotherapy. An exception to this is the anti-epidermal growth factor receptor therapy erlotinib, which yielded a survival benefit in patients with advanced disease in combination with gemcitabine compared with gemcitabine alone, although this was a marginal incremental improvement for which the clinical significant has been heavily debated. More recently, the most significant therapeutic advance in PAC has come from the combination of several cytotoxic agents; infusional 5-FU, irinotecan and oxaliplatin. This combination chemotherapy regimen, known as FOLFIRINOX, improved survival in patients with an excellent functional status and stage IV disease by 4.3 months compared with gemcitabine alone. This improvement in survival did come at the cost expectedly of a significant increase in toxicities, including gastrointestinal and hematologic particularly. Other gemcitabine-based combination chemotherapy regimens including gemcitabine and platinum analogs and gemcitabine and capecitabine have consistently shown an increased response rate but no OS benefit in individual trials; albeit pooled and meta-analyses have indicated a survival benefit in good performance status patient for both these cytotoxic combinations. Accordingly, the 5-year survival for patients with PAC remains <5%, with an annual disease-specific mortality which approaches the incidence. The challenge remains therefore, to develop more effective systemic therapies against this challenging malignancy. Recent progress toward understanding the genetic events in the development of PAC, in combination with advances in the field of pharmacogenomics offer hope that we may build on achievements to-date to develop more effective therapeutic strategies for PAC in years to come.

Constitutive K-RasG12D activation of ERK2 specifically regulates 3D invasion of human pancreatic cancer cells via MMP-1

Pancreatic ductal adenocarcinomas (PDAC) are highly invasive and metastatic neoplasms commonly unresponsive to current drug therapy. Overwhelmingly, PDAC harbors early constitutive, oncogenic mutations in K-Ras(G12D) that exist prior to invasion. Histologic and genetic analyses of human PDAC biopsies also exhibit increased expression of extracellular signal-regulated kinase (ERK) 1/2 and proinvasive matrix metalloproteinases (MMP), indicators of poor prognosis. However, the distinct molecular mechanisms necessary for K-Ras/ERK1/2 signaling and its influence on MMP-directed stromal invasion in primary human pancreatic ductal epithelial cells (PDEC) have yet to be elucidated in three-dimensions. Expression of oncogenic K-Ras(G12D) alone in genetically defined PDECs reveals increased invadopodia and epithelial-to-mesenchymal transition markers, but only when cultured in a three-dimensional model incorporating a basement membrane analog. Activation of ERK2, but not ERK1, also occurs only in K-Ras(G12D)-mutated PDECs cultured in three-dimensions and is a necessary intracellular signaling event for invasion based upon pharmacologic and short hairpin RNA (shRNA) inhibition. Increased active invasion of K-Ras(G12D) PDECs through the basement membrane model is associated with a specific microarray gene expression signature and induction of MMP endopeptidases. Specifically, MMP-1 RNA, its secreted protein, and its proteolytic cleavage activity are amplified in K-Ras(G12D) PDECs when assayed by real-time quantitative PCR, ELISA, and fluorescence resonance energy transfer (FRET). Importantly, shRNA silencing of MMP-1 mimics ERK2 inhibition and disrupts active, vertical PDEC invasion. ERK2 isoform and MMP-1 targeting are shown to be viable strategies to attenuate invasion of K-Ras(G12D)-mutated human pancreatic cancer cells in a three-dimensional tumor microenvironment.

Contribution of epithelial-to-mesenchymal transition and cancer stem cells to pancreatic cancer progression

Pancreatic adenocarcinoma remains among the most lethal of human malignancies. Overall 5-y survival is less than 5%, and only 20% of patients presenting with localized disease amenable to surgical resection. Even in patients who undergo resection, long-term survival remains extremely poor. A major contributor to the aggressiveness of multiple cancers, and pancreatic cancer in particular, is the process of epithelial-to-mesenchymal transition (EMT). This review highlights the growing evidence of EMT in pancreatic cancer progression, focusing on the contribution of EMT to the development of cancer stem cells and on interaction of EMT with other pathways central to cancer progression, such as Hedgehog signaling, the K-ras oncogene, and transforming growth factor-beta (TGF-β). We will also discuss EMT-targeting agents currently in development and in clinical trials that may help to reduce the morbidity and mortality associated with pancreatic cancer.