Involvement of matrix metalloproteinase-2 activity in invasion and metastasis of pancreatic carcinoma

Molecular and metabolic regulation of immunosuppression in metastatic pancreatic ductal adenocarcinoma

Immunosuppression is a hallmark of pancreatic ductal adenocarcinoma (PDAC), contributing to early metastasis and poor patient survival. Compared to the localized tumors, current standard-of-care therapies have failed to improve the survival of patients with metastatic PDAC, that necessecitates exploration of novel therapeutic approaches. While immunotherapies such as immune checkpoint blockade (ICB) and therapeutic vaccines have emerged as promising treatment modalities in certain cancers, limited responses have been achieved in PDAC. Therefore, specific mechanisms regulating the poor response to immunotherapy must be explored. The immunosuppressive microenvironment driven by oncogenic mutations, tumor secretome, non-coding RNAs, and tumor microbiome persists throughout PDAC progression, allowing neoplastic cells to grow locally and metastasize distantly. The metastatic cells escaping the host immune surveillance are unique in molecular, immunological, and metabolic characteristics. Following chemokine and exosomal guidance, these cells metastasize to the organ-specific pre-metastatic niches (PMNs) constituted by local resident cells, stromal fibroblasts, and suppressive immune cells, such as the metastasis-associated macrophages, neutrophils, and myeloid-derived suppressor cells. The metastatic immune microenvironment differs from primary tumors in stromal and immune cell composition, functionality, and metabolism. Thus far, multiple molecular and metabolic pathways, distinct from primary tumors, have been identified that dampen immune effector functions, confounding the immunotherapy response in metastatic PDAC. This review describes major immunoregulatory pathways that contribute to the metastatic progression and limit immunotherapy outcomes in PDAC. Overall, we highlight the therapeutic vulnerabilities attributable to immunosuppressive factors and discuss whether targeting these molecular and immunological "hot spots" could improve the outcomes of PDAC immunotherapies.

5-FU-miR-15a Inhibits Activation of Pancreatic Stellate Cells by Reducing YAP1 and BCL-2 Levels In Vitro

Chronic pancreatitis is characterized by chronic inflammation and fibrosis, processes heightened by activated pancreatic stellate cells (PSCs). Recent publications have demonstrated that miR-15a, which targets YAP1 and BCL-2, is significantly downregulated in patients with chronic pancreatitis compared to healthy controls. We have utilized a miRNA modification strategy to enhance the therapeutic efficacy of miR-15a by replacing uracil with 5-fluorouracil (5-FU). We demonstrated increased levels of YAP1 and BCL-2 (both targets of miR-15a) in pancreatic tissues obtained from Ptf1aCreERTM and Ptf1aCreERTM;LSL-KrasG12D mice after chronic pancreatitis induction as compared to controls. In vitro studies showed that delivery of 5-FU-miR-15a significantly decreased viability, proliferation, and migration of PSCs over six days compared to 5-FU, TGFβ1, control miR, and miR-15a. In addition, treatment of PSCs with 5-FU-miR-15a in the context of TGFβ1 treatment exerted a more substantial effect than TGFβ1 alone or when combined with other miRs. Conditioned medium obtained from PSC cells treated with 5-FU-miR-15a significantly inhibits the invasion of pancreatic cancer cells compared to controls. Importantly, we demonstrated that treatment with 5-FU-miR-15a reduced the levels of YAP1 and BCL-2 observed in PSCs. Our results strongly suggest that ectopic delivery of miR mimetics is a promising therapeutic approach for pancreatic fibrosis and that 5-FU-miR-15a shows specific promise.

Calibrating models of cancer invasion: parameter estimation using approximate Bayesian computation and gradient matching

We present two different methods to estimate parameters within a partial differential equation model of cancer invasion. The model describes the spatio-temporal evolution of three variables-tumour cell density, extracellular matrix density and matrix degrading enzyme concentration-in a one-dimensional tissue domain. The first method is a likelihood-free approach associated with approximate Bayesian computation; the second is a two-stage gradient matching method based on smoothing the data with a generalized additive model (GAM) and matching gradients from the GAM to those from the model. Both methods performed well on simulated data. To increase realism, additionally we tested the gradient matching scheme with simulated measurement error and found that the ability to estimate some model parameters deteriorated rapidly as measurement error increased.

Matrix Metalloproteases in Pancreatic Ductal Adenocarcinoma: Key Drivers of Disease Progression?

Pancreatic cancer is a dismal disorder that is histologically characterized by a dense fibrotic stroma around the tumor cells. As the extracellular matrix comprises the bulk of the stroma, matrix degrading proteases may play an important role in pancreatic cancer. It has been suggested that matrix metalloproteases are key drivers of both tumor growth and metastasis during pancreatic cancer progression. Based upon this notion, changes in matrix metalloprotease expression levels are often considered surrogate markers for pancreatic cancer progression and/or treatment response. Indeed, reduced matrix metalloprotease levels upon treatment (either pharmacological or due to genetic ablation) are considered as proof of the anti-tumorigenic potential of the mediator under study. In the current review, we aim to establish whether matrix metalloproteases indeed drive pancreatic cancer progression and whether decreased matrix metalloprotease levels in experimental settings are therefore indicative of treatment response. After a systematic review of the studies focusing on matrix metalloproteases in pancreatic cancer, we conclude that the available literature is not as convincing as expected and that, although individual matrix metalloproteases may contribute to pancreatic cancer growth and metastasis, this does not support the generalized notion that matrix metalloproteases drive pancreatic ductal adenocarcinoma progression.

The Vacuolar H+ ATPase α3 Subunit Negatively Regulates Migration and Invasion of Human Pancreatic Ductal Adenocarcinoma Cells

Increased metabolic acid production and upregulation of net acid extrusion render pH homeostasis profoundly dysregulated in many cancers. Plasma membrane activity of vacuolar H+ ATPases (V-ATPases) has been implicated in acid extrusion and invasiveness of some cancers, yet often on the basis of unspecific inhibitors. Serving as a membrane anchor directing V-ATPase localization, the a subunit of the V0 domain of the V-ATPase (ATP6V0a1-4) is particularly interesting in this regard. Here, we map the regulation and roles of ATP6V0a3 in migration, invasion, and growth in pancreatic ductal adenocarcinoma (PDAC) cells. a3 mRNA and protein levels were upregulated in PDAC cell lines compared to non-cancer pancreatic epithelial cells. Under control conditions, a3 localization was mainly endo-/lysosomal, and its knockdown had no detectable effect on pHi regulation after acid loading. V-ATPase inhibition, but not a3 knockdown, increased HIF-1 expression and decreased proliferation and autophagic flux under both starved and non-starved conditions, and spheroid growth of PDAC cells was also unaffected by a3 knockdown. Strikingly, a3 knockdown increased migration and transwell invasion of Panc-1 and BxPC-3 PDAC cells, and increased gelatin degradation in BxPC-3 cells yet decreased it in Panc-1 cells. We conclude that in these PDAC cells, a3 is upregulated and negatively regulates migration and invasion, likely in part via effects on extracellular matrix degradation.

Development of a Tumor-Responsive Nanopolyplex Targeting Pancreatic Cancer Cells and Stroma

Desmoplasia plays a pivotal role in promoting pancreatic cancer progression and is associated with poor clinical outcome. Targeting the desmoplastic tumor microenvironment in combination with chemotherapy is therefore a promising strategy for pancreatic cancer therapy. Here, we report a novel biodegradable copolymer to codeliver LY2109761 (a TGF-β receptor I/II inhibitor) and CPI-613 (a novel chemotherapy agent) to desmoplastic stroma and tumor cells, respectively, in the tumor microenvironment. Hydrophobic CPI-613 is conjugated to the hydrophilic copolymer via a newly designed MMP-2-responsive linker to form a trigger-responsive nanopolyplex. LY2109761 is hydrophobic and encapsulated into the hydrophobic core of the nanopolyplex. The resulting nanopolyplex is modified with a plectin-1-targeting peptide to enhance the accumulation of the nanopolyplex in pancreatic tumors. The nanopolyplex aims to normalize the stroma by blocking the interaction between tumor cells and pancreatic stellate cells to inhibit the activation of pancreatic stellate cells and subsequently reduce the dense extracellular matrix. Normalized stroma increases the penetration of the nanopolyplex into the tumor. The nanopolyplex shows enhanced accumulation in xenograft pancreatic tumors in a biodistribution study. Moreover, the targeted nanopolyplex markedly inhibits tumor growth in an orthotopic pancreatic cancer mouse model by dual-targeting tumor cells and stroma. Overall, the multifunctional nanopolyplex is a promising platform for pancreatic cancer therapy.

Aberrant expression of PDZ-binding kinase/T-LAK cell-originated protein kinase modulates the invasive ability of human pancreatic cancer cells via the stabilization of oncoprotein c-MYC

High frequency of mortality in patients with pancreatic ductal adenocarcinoma (PDAC) is vastly associated with the invasive and metastatic nature of these cancer cells. Little is known about the factors involved in this invasive/metastatic process. The current challenge in the treatment of these patients is the lack of viable options besides gemcitabine. The aim of this study was to evaluate the role of PDZ-binding kinase (PBK)/T-LAK cell-originated protein kinase (TOPK) in invasive PDAC cells and to determine whether PBK/TOPK expression drives invasiveness in PDAC. Using gain-of-function and loss-of-function studies in established and patient-derived xenograft-PDAC cell lines, and examining patient-derived archival tissue samples, we demonstrate for the first time that PBK/TOPK is upregulated in pancreatic cancer and expression levels are closely associated with the invasive property of pancreatic cancer cells. Modulation of PBK/TOPK causally regulates the invasive ability of PDAC cells. We also demonstrate that two key players in metastatic invasion, matrix metalloproteinases-2 (MMP-2) and MMP-9 gelatinase activity and gene promoter activities, are regulated by PBK/TOPK. Moreover, we demonstrate for the first time that PBK/TOPK provides stability of an oncoprotein, c-MYC, which transcriptionally regulates MMP-2 and MMP-9 in these invasive PDAC cells. Our in vitro and in situ data corroborate that PBK/TOPK is closely associated with the invasive nature of PDAC and reveal a novel mechanism by which the metastatic behavior of human pancreatic cancer cells is regulated. These findings provide a rationale for targeting PBK/TOPK for the therapeutic intervention of invasive/metastatic pancreatic cancer in human.

Silencing of Astrocyte elevated gene-1 (AEG-1) inhibits proliferation, migration, and invasiveness, and promotes apoptosis in pancreatic cancer cells

To investigate the role of Astrocyte elevated gene-1 (AEG-1) in the development and progress of pancreatic cancer, short hairpin RNA (shRNA) was inserted into the RNA interference vector to knock-down the endogenous AEG-1 in two pancreatic cancer cell lines: AsPC-1 and PANC-1. Our results showed that silencing of AEG-1 suppressed the proliferation, colony formation ability, and cell stemness of AsPC-1 and PANC-1 cells, and inhibited their G1-to-S phase transition. Results from apoptosis assay showed that knock-down of AEG-1 led to cell apoptosis. The expression of anti-apoptotic Bcl-2 was downregulated and that of the pro-apoptotic Bax and cleaved caspase-3 was upregulated in AEG-1-silenced pancreatic cancer cells. Further, the capability of AEG-1-silenced cells to migrate and to invade through the Matrigel-coated membrane was weaker, and the expression of matrix metallopeptidase 2 (MMP-2) and MMP-9 were decreased. Moreover, the AKT-β-catenin signaling pathway was inhibited in the cells with knock-down of AEG-1. In addition, the growth of xenograft tumors formed by AsPC-1 and PANC-1 cells was suppressed by AEG-1 shRNA. In conclusion, our study demonstrates that pancreatic cancer cells require AEG-1 to maintain their survival and metastasis, suggesting AEG-1 as a potential target for the treatment of pancreatic cancers.

Prognostic significance of plasma matrix metalloprotease-2 in pancreatic cancer patients

Background & objectives:

Pancreatic cancer has a propensity for wide stromal invasion. Matrix metalloprotease-2 (MMP-2) is a protease that degrades the peri-tumoural tissue and helps in tumour dissemination. Thus, this study was aimed to assess any association of plasma MMP-2 levels with clinicopathological parameters and survival of patients with pancreatic cancer.

Methods:

Plasma samples from 127 pancreatic cancer patients were analyzed for MMP-2 levels by ELISA. Survival and other clinicopathological parameters of patients were analyzed for any correlation with plasma MMP-2 levels.

Results:

The mean MMP-2 levels in pancreatic cancer patients were 560.3±222.0 ng/ml which were significantly elevated compared to chronic pancreatitis patients (P<0.001) and healthy individuals (P<0.05). The plasma levels of MMP-2 significantly correlated with tissue expression of this protease (P=0.004). However, MMP-2 levels did not exhibit any association either with clinicopathological parameters or with survival.

Interpretation & conclusions:

Elevated MMP-2 levels were observed in blood of pancreatic cancer patients which correlated with its tissue expression. However, these levels did not associate with survival or any clinicopathological parameters of patients. Further studies need to be done to confirm the prognostic/clinical significance of MMP-2 in cancer patients before and after surgery.

High Mobility Group Box Protein 1 Serves as a Potential Prognostic Marker of Lung Cancer and Promotes Its Invasion and Metastasis by Matrix Metalloproteinase-2 in a Nuclear Factor-κB-Dependent Manner

Several studies have reported a significant role of high mobility group box protein 1 (HMGB1) in lung cancer. Nevertheless, there is a lack of knowledge regarding the expression of HMGB1 and its correlation with the clinicopathological features of lung cancer. In addition, the potential molecular mechanisms underlying the role of HMGB1 in lung cancer are still unknown. We therefore investigated the clinicopathological and prognostic significance as well as the potential role of HMGB1 in the development and progression of lung cancer. HMGB1 expression in the tumor tissues of the cohort correlated with clinicopathological features. Moreover, lung cell migration and invasion were significantly increased after treatment with HMGB1. The matrix metalloproteinase-2 (MMP-2) expression and activity were upregulated after treatment with HMGB1, while the upregulated expression of MMP-2 stimulated by HMGB1 in lung cancer cells was significantly reduced with the blockage of si-p65. These results indicated that HMGB1 expression was significantly associated with lung cancer progression. We also showed that HMGB1 promoted lung cancer invasion and metastasis by upregulating the expression and activity of MMP-2 in an NF-κB-dependent manner. Taken together, these data suggested that HMGB1 may be a potential prognosis and therapeutic marker for lung cancer.

New therapeutic directions for advanced pancreatic cancer: cell cycle inhibitors, stromal modifiers and conjugated therapies

INTRODUCTION

Pancreatic adenocarcinoma is a devastating malignancy with an extremely poor prognosis. These tumors progress rapidly and somewhat silently with few specific symptoms and are relatively resistant to chemotherapeutic agents. Many agents, including cell cycle inhibitors, are under development for the treatment of this cancer for which there are disappointingly few treatment options. Areas covered: Here we outline the existing approved treatments for advanced pancreatic disease and discuss a range of novel therapies currently under development including cell cycle inhibitors, stromal modifiers and conjugated therapies. We also describe the current state of the pancreatic cancer therapeutics market both past and future. Expert opinion: Despite the recent explosion of novel therapies with an array of unique targets, the core treatment of pancreatic cancer still with traditional cytotoxic agents with a few exceptions. However, as these novel treatments move through the pipeline, we are hopeful that there will soon be a number of effective options for patients with advanced pancreatic cancer.

Molecular-Targeted Agents in Pancreatic Cancer

Background

Despite the acceptance of gemcitabine as the standard first-line agent for the treatment of advanced pancreatic cancer as well as the improved response rates seen with gemcitabine combinations, novel therapies are needed for this disease, which has one of the lowest survival rates. The growing understanding of the molecular basis of pancreatic cancer and the recent introduction of targeted therapeutic agents have initiated novel studies that have the potential to improve on existing treatments.

Methods

We review the rationale and the clinical studies of therapeutic agents that target some of the molecular abnormalities commonly found in pancreatic cancer.

Results

Matrix metalloproteinase inhibitors (MMPIs), farnesyltransferase inhibitors (FTIs), and tyrosine-kinase inhibitors and monoclonal antibodies against growth factors or their receptors are novel agents that have undergone phase II or III trials. Phase III studies of MMPIs, alone or in combination with gemcitabine, and phase III studies of FTIs have produced disappointing results. Other agents in earlier phases of clinical development remain promising.

Conclusions

Despite the negative studies of MMPIs and FTIs, the results of phase II trials of other drugs are encouraging. Targeted agents may improve the prognosis of pancreatic cancer.

Bioinformatics analysis of transcription profiling of solid pseudopapillary neoplasm of the pancreas

Solid pseudopapillary neoplasm (SPN) of the pancreas is a low-grade malignant neoplasm that accounts for ~5% of cystic pancreatic tumors and ~0.9–2.7% of exocrine pancreatic tumors. The transcription profiling data (GSE43795) of 14 SPN and 6 control samples were downloaded from the Gene Expression Omnibus (GEO) database. Using the Limma package, Student's t-tests were performed to identify differentially expressed genes (DEGs) between SPN and control samples [with the following criterion: False discovery rate (FDR)<0.01 and log₂ fold-change (FC)≥3]. Pathway and functional enrichment analyses were performed to investigate the biological processes that the DEGs were involved in. Protein-protein interaction (PPI) network and sub-network analyses were conducted to comprehensively understand the interactions between DEGs. The screened DEGs were further annotated according to information relating to transcription factors and tumor associated genes (TAGs). A total of 710 upregulated and 710 downregulated DEGs were observed, including 74 transcriptional factors and 124 TAGs. Membrane metallo-endopeptidase (MME), matrix metalloproteinase (MMP)-2 and MMP-9 were also identified as key TAGs. Following PPI network analysis, hub nodes of epidermal growth factor receptor (EGFR), proto-oncogene tyrosine protein kinase Fyn (FYN), c-JUN (JUN), glucagon (GCG), c-Myc (MYC) and CD44 were identified, the majority of which participate in the epidermal growth factor receptor (ErbB) and gonadotropin-releasing hormone (GnRH) signaling pathways. A sub-network involving 70 gene nodes was also identified, with EGFR as the central gene. MME, MMP-2 and MMP-9 contribute to proliferative diabetic retinopathy and also involved in SPN. The genes EGFR, FYN, JUN, GCG, MYC and CD44 may therefore be key genes in SPN, and the ErbB and GnRH signaling pathways may be an important contributor to SPN progression.

Differential Diagnosis of Autoimmune Pancreatitis From Pancreatic Cancer by Analysis of Serum Gelatinase Levels

OBJECTIVES

The aim of this study was to analyze serum gelatinases as part of the clinical strategy for the preoperative differentiation between autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDAC). The finding of differential markers will prevent unnecessary surgical resection and allow optimal treatment of these diseases.

METHODS

Quantitative gelatin zymography was applied to analyze all individual gelatinase forms in serum and to define proteinase alterations associated with AIP and PDAC. For this purpose, sera of 130 patients, being 29 with AIP, 33 with chronic pancreatitis, 32 with PDAC, and 36 healthy controls, were first assayed for gelatinase levels by quantitative zymography before further validation by the analysis with commercial sandwich enzyme linked immunosorbent assays.

RESULTS

Serum profiling data obtained by zymography analysis revealed that gelatinase B/matrix metalloproteinase 9 (MMP-9), the neutrophil gelatinase B-associated lipocalin/MMP-9 complex, and gelatinase A/MMP-2 levels were significantly increased in patients with AIP. These proteins are promising markers to discriminate between AIP and PDAC. The best composite parameter, being the ratio of total MMP-9 over MMP-2 levels, can predict 93% of the AIP and 75% of the PDAC correctly. With enzyme linked immunosorbent assay, we confirmed the zymography results.

CONCLUSIONS

Differential gelatinase serum profiles as AIP markers, together with other clinical tests, help to assure the diagnosis of PDAC or AIP.

CCL11-induced eosinophils inhibit the formation of blood vessels and cause tumor necrosis

We previously demonstrated that IL-18 and CCL11 were highly expressed in an NFSA tumor cell line that showed limited angiogenesis and severe necrosis. However, IL-18 was not responsible for the immune cell accumulation and necrosis. Here, we attempted to clarify the relevance of CCL11 in angiogenesis and tumor formation. We established CCL11-overexpressing MS-K cell clones (MS-K-CCL11) to assess the role of CCL11 in immune cell accumulation and angiogenesis. The MS-K-CCL11 cells did not form tumors in mice. MS-K-CCL11-conditioned medium (CM) and recombinant CCL11 induced macrophage and eosinophil differentiation from bone marrow cells. The MS-K-CCL11-CM effectively recruited the differentiated eosinophils. Furthermore, the eosinophils damaged the MS-K, NFSA and endothelial cells in a dose-dependent manner. Administration of an antagonist of CCR3, a CCL11 receptor, to NFSA tumor-bearing mice restored the blood vessel formation and blocked the eosinophil infiltration into the NFSA tumors. Furthermore, other CCL11-overexpressing LM8 clones were established, and their tumor formation ability was reduced compared to the parental LM8 cells, accompanied by increased eosinophil infiltration, blockade of angiogenesis and necrosis. These results indicate that CCL11 was responsible for the limited angiogenesis and necrosis by inducing and attracting eosinophils in the tumors.

In vivo optical imaging of MMP2 immuno protein antibody: tumor uptake is associated with MMP2 activity

Matrix metalloproteinase-2 (MMP2) is important in tumorigenesis, angiogenesis and tumor invasion. In this study, we investigated if the Cy5-tagged small immuno protein targeting the catalytic domain of human MMP2 (aMMP2-SIP) detects MMP2 in tumors non-invasively. For this purpose, we generated MMP2 expressing (empty vector EV) and knock-down (KD) HT1080, U373 and U87 cells, which were injected subcutaneously in the lateral flank of NMRI-nu mice. Optical imaging (Optix MX2) performed at 0.5, 2, 4, 8, 24 and 48 hour post injection (h.p.i.) of Cy5 tagged aMMP2-SIP, indicated significantly lower tumor to background ratios at both 24 (P = 0.0090) and 48 h.p.i. (P < 0.0001) for the U87 MMP2-KD compared to control tumors. No differences were found for HT1080 and U373 models. U87 MMP2-KD tumors had significantly lower MMP2 activity (P < 0.0001) than EV tumors as determined by gelatin zymography in tumor sections and lysates, while no differences were observed between EV and MMP2-KD in HT1080 and U373. In line with these data, only U87 MMP2-KD tumors had a reduced tumor growth compared to control tumors (P = 0.0053). aMMP2-SIP uptake correlates with MMP2 activity and might therefore be a potential non-invasive imaging biomarker for the evaluation of MMP2 activity in tumors.

Neutrophil-Derived Proteases in the Microenvironment of Pancreatic Cancer -Active Players in Tumor Progression

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the fibro-inflammatory microenvironment, consisting of activated pancreatic stellate cells, extracellular matrix proteins, and a variety of inflammatory cells, such as T cells, macrophages, or neutrophils. Tumor-infiltrating immune cells, which are found in nearly all cancers, including PDAC, often fail to eliminate the tumor, but conversely can promote its progression by altering the tumor microenvironment. Pancreatic cancer cells are able to attract polymorphonuclear neutrophils (PMN) via tumor secreted chemokines and in human PDAC, PMN infiltrates can be observed in the vicinity of tumor cells and in the desmoplastic tumor stroma, which correlate with undifferentiated tumor growth and poor prognosis. The behavior of tumor-infiltrating neutrophils in the tumor micromilieu is not yet understood at a mechanistic level. It has been shown that PMN have the potential to kill tumor cells, either directly or by antibody-dependent cell-mediated cytotoxicity, but on the other side various adverse effects of PMN, such as promotion of aggressive tumor growth with epithelial-to-mesenchymal transition and increased metastatic potential, have been described. Recent therapeutic approaches for PDAC focus not only the tumor cell itself, but also elements of the tumor microenvironment. Therefore, the role of PMN and their derived products (e.g. cytokines, proteases) as a new vein for a therapeutic target should be critically evaluated in this context. This review summarizes the current understanding of the interplay between proteases of tumor-infiltrating neutrophils and pancreatic tumor cells and elements of the desmoplastic stroma.

Protease-activated receptor 2 agonist increases cell proliferation and invasion of human pancreatic cancer cells

The aim of this study was to determine the expression of protease-activated receptor 2 (PAR-2) in the human pancreatic cancer cell line SW1990, and to evaluate its effect on cell proliferation and invasion. The expression of PAR-2 protein and mRNA in SW1990 cells was determined by immunocytochemistry and reverse transcription polymerase chain reaction (PCR), respectively. MTT and cell invasion and migration assays, as well as semi-quantitative PCR and zymography analysis, were additionally performed. PAR-2 mRNA was significantly upregulated in the cells treated with trypsin or the PAR-2 activating peptide Ser-Leu-Ile-Gly-Lys-Val (SLIGKV) (P<0.01), but not in the Val-Lys-Gly-Ile-Leu-Ser group (P>0.05). Trypsin and SLIGKV significantly promoted SW1990 cell proliferation in a dose- and time-dependent manner (P<0.05). Compared with the control group, trypsin and SLIGKV significantly increased the mRNA expression (P<0.01) and gelatinolytic activity (P<0.01) of matrix metalloproteinase (MMP)-2. In conclusion, PAR-2 is expressed in SW1990 cells. PAR-2 activation may promote the invasion and migration of human pancreatic cancer cells by increasing MMP-2 expression.

Epigallocatechingallate inhibits migration of human uveal melanoma cells via downregulation of matrix metalloproteinase-2 activity and ERK1/2 pathway

The effects of epigallocatechingallate (EGCG) on the migration and expression of MMP-2 of uveal melanoma cells have not been reported. We studied this effect and relevant signaling pathways in a human uveal melanoma cell line (M17). MTT study found that EGCG did not affect the cell viability of M17 cells up to 100 µM. Wound-healing assay showed that EGCG significantly reduced the migration of melanoma cells in a dose-dependent manner from 20 to 100 µM. Gelatin zymography showed that secreted MMP-2 activity was dose-dependently inhibited by EGCG, whereas the MMP-2 expression at protein and mRNA levels was not affected as determined by western blot and RT-PCR analysis. EGCG significantly increased the expressions of MMP-2 endogenous inhibitors (TIMP-2 and RECK) in M17 cells. Western blot analysis of MAPK signal pathways showed that EGCG significantly decreased phosphorylated ERK1/2 levels, but not p38 and JNK levels, in melanoma cells. ERK1/2 inhibitors also reduced the migration and activity of MMP-2 in M17 cells. The present study suggested EGCG at nontoxic levels could inhibit migration of melanoma cells via downregulation of activities of secreted MMP-2 through the inhibition of the ERK1/2 phosphorylation. Therefore, EGCG may be a promising agent to be explored for the prevention of metastasis of uveal melanoma.

Highly Protective Association of MMP-2-1306C/T Promoter Polymorphism With Asthma in a North Indian Population: A Pilot Study

Purpose

Asthma is the most prevalent disease in India according to the national survey conducted by NFHS 2 in 1998-1999. Matrix metalloproteinase-2 (MMP-2), a collagenase encoded by the MMP-2 gene, degrades the type IV collagen and is responsible for inflammatory responses. This is a pilot study evaluating the role of MMP-2 -1306C/T promoter single nucleotide polymorphism (SNP) in asthma pathogenesis.

Methods

A case-control study was performed with a total of 824 adult subjects, including 410 adult asthmatics and 414 healthy controls from regions of North India. The MMP-2 -1306C/T polymorphism was genotyped by the Tetra-Primer Amplification Refractory Mutation System Polymerase Chain Reaction (Tetra-Primer ARMS PCR).

Results

Statistical analysis of the results for the MMP-2 -1306C/T polymorphism revealed an extremely protective role of the mutant T allele in asthma pathogenesis with OR=0.45, 95% CI (0.35-0.58) and P=0.000. The heterozygous CT genotype also conferred protection from asthma with OR=0.37, 95% CI (0.27-0.51) and P=0.000. The homozygous TT genotype was also significantly associated with asthma with OR=0.35, 95% CI (0.16-0.72) and P=0.002. Moreover, the polymorphism was significantly associated with all the phenotypic traits of the disease.

Conclusion

The MMP-2 -1306C/T promoter polymorphism confers significant protection from asthma in the studied North Indian population

Chlorotoxin-Fc fusion inhibits release of MMP-2 from pancreatic cancer cells

Chlorotoxin (CTX) is a 36-amino acid peptide derived from Leiurus quinquestriatus (scorpion) venom, which inhibits low-conductance chloride channels in colonic epithelial cells. It has been reported that CTX also binds to matrix metalloproteinase-2 (MMP-2), membrane type-1 MMP, and tissue inhibitor of metalloproteinase-2, as well as CLC-3 chloride ion channels and other proteins. Pancreatic cancer cells require the activation of MMP-2 during invasion and migration. In this study, the fusion protein was generated by joining the CTX peptide to the amino terminus of the human IgG-Fc domain without a hinge domain, the monomeric form of chlorotoxin (M-CTX-Fc). The resulting fusion protein was then used to target pancreatic cancer cells (PANC-1) in vitro. M-CTX-Fc decreased MMP-2 release into the media of PANC-1 cells in a dose-dependent manner. M-CTX-Fc internalization into PANC-1 cells was observed. When the cells were treated with chlorpromazine (CPZ), the internalization of the fusion protein was reduced, implicating a clathrin-dependent internalization mechanism of M-CTX-Fc in PANC-1 cells. Furthermore, M-CTX-Fc clearly exhibited the inhibition of the migration depending on the concentration, but human IgG, as negative control of Fc, was not affected. The M-CTX-Fc may be an effective instrument for targeting pancreatic cancer.

O-phenyl carbamate and phenyl urea thiiranes as selective matrix metalloproteinase-2 inhibitors that cross the blood-brain barrier

Brain metastasis occurs in 20-40% of cancer patients. Treatment is mostly palliative, and the inability of most drugs to penetrate the brain presents one of the greatest challenges in the development of therapeutics for brain metastasis. Matrix metalloproteinase-2 (MMP-2) plays important roles in invasion and vascularization of the central nervous system and represents a potential target for treatment of brain metastasis. Carbonate, O-phenyl carbamate, urea, and N-phenyl carbamate derivatives of SB-3CT, a selective and potent gelatinase inhibitor, were synthesized and evaluated. The O-phenyl carbamate and urea variants were selective and potent inhibitors of MMP-2. Carbamate 5b was metabolized to the potent gelatinase inhibitor 2, which was present at therapeutic concentrations in the brain. In contrast, phenyl urea 6b crossed the blood-brain barrier, however, higher doses would result in therapeutic brain concentrations. Carbamate 5b and urea 6b show potential for intervention of MMP-2-dependent diseases such as brain metastasis.

Prognostic significance of extracellular matrix degrading enzymes-cathepsin L and matrix metalloproteases-2 [MMP-2] in human pancreatic cancer

In the present study, we assessed the expression of extracellular matrix (ECM) degrading proteases-cathepsin L and matrix metalloprotease-2 (MMP-2) in pancreatic cancer tissue and correlated their levels with clinicopathological parameters and survival. Both the proteases were expressed in the majority of the tumor tissues examined. Staining intensity of cathepsin L was significantly higher in the tumor stroma compared to tumor epithelium while MMP-2 staining showed no such difference. Both proteases showed correlation with some of the clinicopathological parameters but only cathepsin L expression in tumor epithelium predicted a poor prognosis for the disease.

Caveolin-1 as a promoter of tumour spreading: when, how, where and why

Caveolae are non-clathrin invaginations of the plasma membrane in most cell types; they are involved in signalling functions and molecule trafficking, thus modulating several biological functions, including cell growth, apoptosis and angiogenesis. The major structural protein in caveolae is caveolin-1, which is known to act as a key regulator in cancer onset and progression through its role as a tumour suppressor. Caveolin-1 can also promote cell proliferation, survival and metastasis as well as chemo- and radioresistance. Here, we discuss recent findings and novel concepts that support a role for caveolin-1 in cancer development and its distant spreading. We also address the potential application of caveolin-1 in tumour therapy and diagnosis.

ALCAM regulates motility, invasiveness, and adherens junction formation in uveal melanoma cells

ALCAM, a member of the immunoglobulin superfamily, has been implicated in numerous developmental events and has been repeatedly identified as a marker for cancer metastasis. Previous studies addressing ALCAM's role in cancer have, however, yielded conflicting results. Depending on the tumor cell type, ALCAM expression has been reported to be both positively and negatively correlated with cancer progression and metastasis in the literature. To better understand how ALCAM might regulate cancer cell behavior, we utilized a panel of defined uveal melanoma cell lines with high or low ALCAM levels, and directly tested the effects of manipulating these levels on cell motility, invasiveness, and adhesion using multiple assays. ALCAM expression was stably silenced by shRNA knockdown in a high-ALCAM cell line (MUM-2B); the resulting cells displayed reduced motility in gap-closure assays and a reduction in invasiveness as measured by a transwell migration assay. Immunostaining revealed that the silenced cells were defective in the formation of adherens junctions, at which ALCAM colocalizes with N-cadherin and ß-catenin in native cells. Additionally, we stably overexpressed ALCAM in a low-ALCAM cell line (MUM-2C); intriguingly, these cells did not exhibit any increase in motility or invasiveness, indicating that ALCAM is necessary but not sufficient to promote metastasis-associated cell behaviors. In these ALCAM-overexpressing cells, however, recruitment of ß-catenin and N-cadherin to adherens junctions was enhanced. These data confirm a previously suggested role for ALCAM in the regulation of adherens junctions, and also suggest a mechanism by which ALCAM might differentially enhance or decrease invasiveness, depending on the type of cadherin adhesion complexes present in tissues surrounding the primary tumor, and on the cadherin status of the tumor cells themselves.

Keratinocyte growth factor induces matrix metalloproteinase-9 expression and correlates with venous invasion in pancreatic cancer

Keratinocyte growth factor (KGF), also known as fibroblast growth factor-7, and KGF receptor (KGFR) play important roles in the growth of epithelial cells and are overexpressed in a variety of malignant epithelial tumors, including pancreatic ductal adenocarcinoma (PDAC). We previously reported that co-expression of KGF and KGFR in PDAC is associated with venous invasion, enhanced vascular endothelial growth factor A expression and poor prognosis. Matrix metalloproteinase-9 (MMP-9) is known to participate in the degradation of type IV collagen, which is a primary component of extracellular matrices in the vascular basement membrane. In the present study, we examined the expression and roles of KGF, KGFR and MMP-9 in human PDAC cell lines and tissues. Quantitative real-time polymerase chain reaction analysis demonstrated the expression of MMP-9 mRNA in all eight PDAC cell lines. KGF, KGFR and MMP-9 were, respectively, expressed in 27 (43%), 23 (37%) and 35 (56%) of 63 patients. Each expression of KGF, KGFR or MMP-9 correlated positively with venous invasion. Furthermore, expression of KGF or MMP-9 correlated positively with liver metastasis. KGF-positive cases exhibited shorter survival than KGF-negative cases, while KGFR and MMP-9 expression were unrelated to prognosis. Administration of recombinant human KGF increased MMP-9 expression in PDAC cells, while transient transfection with short hairpin RNAs targeting KGF transcripts reduced MMP-9 expression in PDAC cells. Moreover, recombinant human KGF significantly enhanced migration and invasion of PDAC cells. These findings suggest that KGF and KGFR promote venous invasion via MMP-9 in PDAC, and closely correlate with liver metastasis. The KGF/KGFR pathway may be a critical therapeutic target for PDAC metastasis.

Proteolytic action of kallikrein-related peptidase 7 produces unique active matrix metalloproteinase-9 lacking the C-terminal hemopexin domains

The gelatinases, matrix metalloproteinase (MMP)-9 and -2, are produced as latent, inactive enzymes that can be proteolytically activated by a number of proteases. In many normal and pathological conditions, where the expression of MMPs is deregulated, changes in the expression of other proteases have also been reported. Human kallikrein-related peptidase 7 (KLK7), a chymotryptic-like serine protease, is overexpressed in many different types of neoplastic conditions, which have also been shown to express high levels of both MMP-9 and -2. Since the activation of MMPs by KLK7 has never been examined, we sought to determine whether KLK7 can activate these MMPs. To test this hypothesis KLK7 was incubated with the recombinant MMPs and the products of the reaction were analyzed for their activity. Incubation of proMMP-9 with KLK7 resulted in the production of a novel truncated, active MMP-9 lacking the C-terminal hemopexin domains. In contrast, KLK7 degraded, but did not activate, proMMP-2. The novel activation of proMMP-9 by KLK7 was further confirmed using conditioned medium prepared from an MMP-9-expressing cell line, MDA-MMP-9. Our results clearly establish that KLK7 activates proMMP-9 to produce a novel truncated, active MMP-9 product not generated by other proteases. These findings suggest that KLK7 may play an important role in the activation of MMP-9 in tumors that express high levels of both these proteases and the resulting truncated MMP may possess altered substrate specificities compared with full-length MMP-9 activated by other proteases.

The evolution of imaging in cancer: current state and future challenges

Molecular imaging allows for the remote, noninvasive sensing and measurement of cellular and molecular processes in living subjects. Drawing upon a variety of modalities, molecular imaging provides a window into the biology of cancer from the subcellular level to the patient undergoing a new, experimental therapy. As signal transduction cascades and protein interaction networks become clarified, an increasing number of relevant targets for cancer therapy--and imaging--become available. Although conventional imaging is already critical to the management of patients with cancer, molecular imaging will provide even more relevant information, such as early detection of changes with therapy, identification of patient-specific cellular and metabolic abnormalities, and the disposition of therapeutic, gene-tagged cells throughout the body--all of which will have a considerable impact on morbidity and mortality. This overview discusses molecular imaging in oncology, providing examples from a variety of modalities, with an emphasis on emerging techniques for translational imaging.

X-ray irradiation and Rho-kinase inhibitor additively induce invasiveness of the cells of the pancreatic cancer line, MIAPaCa-2, which exhibits mesenchymal and amoeboid motility

Tumor cells can migrate and invade tissue by two modes of motility: mesenchymal and amoeboid. X-ray or γ-ray irradiation increases the invasiveness of tumor cells with mesenchymal motility through the induction of matrix metalloproteinases (MMP), and this increase is suppressed by MMP inhibitors (MMPI). However, the effects of X-ray or γ-ray irradiation on the invasiveness of tumor cells with amoeboid motility remain unclear. We investigated the effect of irradiation on amoeboid motility by using cells of the human pancreatic cancer line, MIAPaCa-2, which exhibits both modes of motility. The X-ray-induced invasiveness of MIAPaCa-2 cells was associated with the upregulation of MMP2 at both the RNA and protein levels and was inhibited by MMPI treatment. Amoeboid-mesenchymal transition was slightly induced after irradiation. The MMPI treatment caused mesenchymal-amoeboid transition without significant increase in invasiveness, while the ROCK inhibitor (ROCKI) stimulated amoeboid-mesenchymal transition and enhanced invasiveness under both non-irradiated and irradiated conditions. This ROCKI-induced transition was accompanied by the upregulation of MMP2 mRNA and protein. Exposure to both irradiation and ROCKI further enhanced MMP2 expression and had an additive effect on the invasiveness of MIAPaCa-2 cells. Additionally, exposure to MMPI led to significant suppression of both radiation-induced and the basal invasiveness of MIAPaCa-2 cells. This suggests that ROCKI treatment, especially with concomitant X-ray irradiation, can induce invasion of cancer cells and should be used only for certain types of cancer cells. Simultaneous use of inhibitors, ROCKI and MMPI may be effective in suppressing invasiveness under both X-ray-irradiated and non-irradiated conditions.

Transient gene silencing of galectin-3 suppresses pancreatic cancer cell migration and invasion through degradation of β-catenin

Pancreatic cancer is a leading cause of cancer-related mortality and often has a poor prognosis because of its late diagnosis, aggressive local invasion, early metastasis and poor response to chemotherapy. The chemotherapeutic agent gemcitabine is effective for treating advanced pancreatic cancer, but its efficacy remains less than satisfactory. It is expected that further investigation of pancreatic cancer cell invasion and development of strategies to block this process should improve the disease prognosis. In this study, we tested our hypothesis that galectin-3 (gal-3), a multifunctional member of the β-galactoside-binding protein family, may regulate pancreatic cancer cell motility and silencing of it inhibit cell motility. Previous studies demonstrated that this protein is associated with tumor cell adhesion, proliferation, differentiation, angiogenesis, apoptosis and metastasis. Here, we used gal-3 small interfering RNA (siRNA) to silence its expression in various pancreatic cancer cell lines to determine whether gal-3 regulates cell proliferation, migration and invasion in vitro. We found that silencing gal-3 reduced cellular migration and invasion, but failed to affect proliferation. In gal-3 siRNA-transfected cells, we detected a decrease in β-catenin expression, an important signal for cancer cell invasion, which was caused by downregulation of phosphorylated Akt and GSK-3β. We also found that matrix metalloproteinase (MMP)-2 expression was reduced by gal-3 silencing. These results indicate that gal-3-mediated invasion via MMP-2 regulated by β-catenin degradation is initiated by Akt phosphorylation in pancreatic cancer cells. Our results suggest that gal-3 can be a novel therapeutic target in pancreatic cancer.

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.

Establishment and characterization of a new human pancreatic adenocarcinoma cell line with high metastatic potential to the lung

BACKGROUND

Pancreatic cancer is still associated with devastating prognosis. Real progress in treatment options has still not been achieved. Therefore new models are urgently needed to investigate this deadly disease. As a part of this process we have established and characterized a new human pancreatic cancer cell line.

METHODS

The newly established pancreatic cancer cell line PaCa 5061 was characterized for its morphology, growth rate, chromosomal analysis and mutational analysis of the K-ras, EGFR and p53 genes. Gene-amplification and RNA expression profiles were obtained using an Affymetrix microarray, and overexpression was validated by IHC analysis. Tumorigenicity and spontaneous metastasis formation of PaCa 5061 cells were analyzed in pfp-/-/rag2-/- mice. Sensitivity towards chemotherapy was analysed by MTT assay.

RESULTS

PaCa 5061 cells grew as an adhering monolayer with a doubling time ranging from 30 to 48 hours. M-FISH analyses showed a hypertriploid complex karyotype with multiple numerical and unbalanced structural aberrations. Numerous genes were overexpressed, some of which have previously been implicated in pancreatic adenocarcinoma (GATA6, IGFBP3, IGFBP6), while others were detected for the first time (MEMO1, RIOK3). Specifically highly overexpressed genes (fold change > 10) were identified as EGFR, MUC4, CEACAM1, CEACAM5 and CEACAM6. Subcutaneous transplantation of PaCa 5061 into pfp-/-/rag2-/- mice resulted in formation of primary tumors and spontaneous lung metastasis.

CONCLUSION

The established PaCa 5061 cell line and its injection into pfp-/-/rag2-/- mice can be used as a new model for studying various aspects of the biology of human pancreatic cancer and potential treatment approaches for the disease.

Netrin-1 mediates early events in pancreatic adenocarcinoma progression, acting on tumor and endothelial cells

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. It is characterized by substantial tumor cell invasion and early-stage metastasis. We developed an in vivo model to analyze interactions between cancer and stromal cells during early stages of PDAC.

METHODS

Human pancreatic adenocarcinoma cells were grafted onto the chick chorioallantoic membrane (CAM). Human and chicken GeneChips were used simultaneously to study gene regulation during PDAC cell invasion. Bioinformatic analysis was used to identify human orthologs and cell specificity of gene expression. The effects of netrin-1 encoded by NTN1 were investigated in adhesion, invasion, and apoptosis assays. The effects of NTN1 silencing with small interfering RNAs were investigated in PDAC cells in vivo. NTN1 expression was measured in human PDAC samples.

RESULTS

PDAC cells rapidly invade the CAM stroma and remodel the CAM vasculature. Around 800 stromal genes were up-regulated by >2-fold; the angiogenesis regulators vascular endothelial growth factor D, thrombospondin 1, and CD151 were among the most highly regulated genes. Silencing of tumor cell NTN1, which is up-regulated 4-fold in the PDAC model, inhibited tumor cell invasion in vivo. Netrin-1 conferred apoptosis resistance to tumor and endothelial cells in vitro, induced their invasion, and provided an adhesive substrate for tumor cells. NTN1 and its gene product are strongly overexpressed in human PDAC samples.

CONCLUSIONS

We developed a useful tool to study the invasive mechanisms of early-stage PDAC. Netrin-1 might be an important regulator of pancreatic tumor growth that functions in tumor and endothelial cells.

Hypoxia-reoxygenation increase invasiveness of PANC-1 cells through Rac1/MMP-2

Pancreatic cancer is an aggressive malignancy with proclivity to early metastasis. High expression and activation of the collagenase matrix metalloproteinase-2 (MMP-2) have been found in human pancreatic cancer tissues, being these increased levels of active MMP-2 correlated to tumor invasion and metastasis. Hypoxia and reoxygenation (H-R) are critical pathophysiological conditions during ischemia-reperfusion injury, which has been shown to enhance both invasion and metastasis. In the present study, we investigated the effects of H-R on MMP-2 levels and the invasiveness properties of human pancreatic cancer cells PANC-1. Using specific inhibitors, we found that H-R treatment of these tumor cells induced secretion and activation of MMP-2, which was required for H-R-stimulated basement membrane degradation and cell invasion. Our results also indicate that signaling events involved in H-R-enhanced PANC-1 invasiveness comprehend PI3K-dependent activation of Rac1, which mediated the formation of NADPH-generated reactive oxygen species responsible for MMP-2 secretion and activation.

Mammographic density and matrix metalloproteinases in breast tissue

Mammographic density is a strong risk factor for breast cancer, yet the underlying histopathologic correlates are not clear. Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play important roles in multiple stages of tumorigenesis. This study examined the association between mammographic density and expression of MMPs 1, 3, 9, and 12 and TIMP3 in benign and malignant breast tissue of 277 women with mainly Caucasian and Japanese ancestry. Tissue microarrays with up to 4 benign and 4 malignant cores per woman were stained immunohistochemically and evaluated. Digitized prediagnostic mammograms were assessed for densities using a computer-assisted method. General linear models adjusted for known confounders were applied to estimate mean densities by staining category. Strong expression of all MMPs was about twice as frequent in malignant as in benign tissue, while TIMP3 expression in stromal tissue was higher in benign than malignant cores. For MMP3 and 9, less than 10% of cores stained positive; thus, they were not further analyzed. None of the markers showed a statistically significant association with breast density in the entire study population and ethnic-specific results were conflicting and difficult to explain. Although not statistically significant, mean density was consistently lower with more extensive TIMP3 expression in stromal and epithelial tissue. These findings indicate that the higher breast cancer risk in women with dense breasts may be influenced by lower TIMP3 expression. However, future investigations into activities and ratios of additional proteases and their inhibitors as well as other pathways, such as inflammation, are needed.

Caveolin-1 regulating the invasion and expression of matrix metalloproteinase (MMPs) in pancreatic carcinoma cells

The gelatinases B (MMP9) and A (MMP2) are two members of the matrix metalloproteinase (MMPs) family that are expressed in human cancer, and play a critical role in tumor cell invasion and metastasis. Caveolin-1 (Cav1) has recently been identified as a tumor metastasis modifier gene. However, the effect and mechanism of Cav1 in pancreatic carcinoma cell invasion remain unknown. In this study, we investigated the expression of Cav1, MMP2, and MMP9 in several different pancreatic carcinoma cell lines. We transfected pcDNA3.0-Cav1 plasmid and Cav1 siRNA into SW1990 and Bxpc3 cells, respectively. Using cell invasion assay, we found that overexpression of Cav1 inhibited cell invasion, whereas the knockdown of Cav1 in Bxpc3 cells promoted cell invasion. Moreover, to explore the mechanisms underlying these observations, we further investigated the expression of MMP2, MMP9, phospho-Akt, and phospho-Erk by Western blot, and the activities of MMP2 and MMP9 by gelatin zymography. The results indicated that Cav1 gene could inhibit pancreatic carcinoma cell invasion, at least in part, probably through Erk-MMP signal pathway, suggesting that the endogenous expression or re-expression of Cav1 might help therapeutically reduce their invasive potential in pancreatic carcinoma cells.

Low-level expression of Smad7 correlates with lymph node metastasis and poor prognosis in patients with pancreatic cancer

BACKGROUND

Whether Smad7 acts as a tumor proliferation promoting factor or as a metastatic suppressor in human pancreatic cancer remains unclear. This study aims to determine the prognostic value of Smad7 in patients with pancreatic adenocarcinoma.

METHODS

Surgical specimens obtained from 71 patients with pancreatic adenocarcinoma were immunohistochemically assessed for Smad7, Ki-67, MMP2, CD34, and Smad4 expression. The relationship between Smad7 expression and the clinicopathological characteristics of patients with pancreatic adenocarcinoma were also evaluated.

RESULTS

Fifty-one of 71 specimens (71.8%) were Smad7 positive and 20 specimens were Smad7 negative. Negative expression of Smad7 correlated with lymph node metastasis, liver metastasis after surgery, and a poor survival rate (P = 0.0004, 0.0044, and 0.0003, respectively). We also found an inverse correlation between the expression of Smad7 and MMP2 (P = 0.0189). Multivariate analysis revealed that Smad7 expression was an independent prognostic factor [hazard ratio (HR) 0.3902; 95% confidence interval (CI) 0.1839-0.8277; P = 0.0142]. Furthermore, in both Smad4-negative and Smad4-positive groups, survival of patients with Smad7-positive tumors was significantly better than those with Smad7-negative tumors (both P < 0.0001).

CONCLUSIONS

We conclude that low-level expression of Smad7 in pancreatic cancer is significantly associated with lymph node metastasis, high MMP2 expression, and poor prognosis.

Prognostic value of metastin expression in human pancreatic cancer

BACKGROUND

KiSS-1 was identified as a metastasis-suppressing gene in melanoma cells. The KiSS-1 gene product (metastin) was isolated from human placenta as the ligand of GPR54, a G-protein-coupled receptor. The role of metastin and GPR54 in tumor progression is not fully understood.

METHODS

We investigated the clinical significance of metastin and GPR54 expression in pancreatic cancer. We evaluated immunohistochemical expression of metastin and GPR54 in pancreatic ductal adenocarcinoma tissues obtained from 53 consecutive patients who underwent resection between July 2003 and May 2007 at Kyoto University Hospital. In 23 consecutive patients, the plasma metastin level was measured before surgery by enzyme immunoassay.

RESULTS

Strong immunohistochemical expression of metastin was detected in 13 tumors (24.5%), while strong expression of GPR54 was detected in 30 tumors (56.6%). Tumors that were negative for both metastin and GPR54 expression were significantly larger than tumors that were positive for either metastin or GPR54 (p = 0.047). Recurrence was less frequent in patients who had metastin-positive tumors compared with those who had metastin-negative tumors (38.5% versus 70.0%, p = 0.04). Strong expression of metastin and GPR54 was significantly correlated with longer survival (p = 0.02). Metastin expression by pancreatic cancer was an independent prognostic factor for longer survival (hazard ratio, 2.1; 95% confidence interval, 1.1-4.7; p = 0.03), and the patients with a high plasma metastin level (n = 6) did not die after surgical resection.

CONCLUSION

Strong expression of metastin and GPR54 by pancreatic cancer is associated with longer survival. Metastin expression is an independent prognostic factor for the survival of pancreatic cancer patients. The plasma metastin level could become a noninvasive prognostic factor for the assessment of pancreatic cancer.

EGF promotes invasion by PANC-1 cells through Rac1/ROS-dependent secretion and activation of MMP-2

Cancer metastasis involves tumor cells invading the surrounding tissue. Remodeling of tissue barriers depends on the ability of tumor cells to degrade the surrounding collagen matrix and then migrate through the matrix defects. Epidermal growth factor (EGF) has been shown to regulate tumor cell invasion through activation of matrix metalloproteinase-2 (MMP-2) in various tumor cell types. In the present study, we investigated the role of MMP-2 and the signaling pathway involved in EGF-promoted invasion by human pancreatic cancer cells PANC-1. Using specific inhibitors, we found that EGF stimulation of these tumor cells induced secretion and activation of the collagenase MMP-2, which was required for EGF-stimulated basement membrane degradation and cell invasion. Our results also indicate that signaling events downstream of EGF receptor involved PI3K- and Src-dependent activation of Rac1, which mediated the NADPH-generated reactive oxygen species responsible for MMP-2 secretion and activation.

Targeting of extracellular proteases required for the progression of pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDA) is the fourth leading cause of cancer-related death in the United States. Its lethality is due, in large part, to its resistance to traditional chemotherapeutics. As a result, there is an enormous effort being put into basic research to identify proteins that are required for PDA progression so that they may be specifically targeted for therapy.

OBJECTIVE

To compile and analyze the evidence that suggests that extracellular proteases are significant contributors to PDA progression.

METHODS

We focus on three different extracellular protease subclasses expressed in PDA: metalloproteases, serine proteases and cathepsins. Based on data from PDA and other cancers, we suggest their probable roles in PDA.

RESULTS/CONCLUSIONS

Of the proteases expressed in PDA, many appear to have overlapping functions, based on the substrates they process, making therapeutics complicated. Two protease families most likely to have unique, critical functions during tumor progression, and therefore strong potential as therapeutic targets, are the a disintegrin and metalloproteases (ADAMs) and the cathepsins.

Biophytum sensitivum (L.) DC Inhibits Tumor Cell Invasion and Metastasis Through a Mechanism Involving Regulation of MMPs, Prolyl Hydroxylase, Lysyl Oxidase, nm23, ERK-1, ERK-2, STAT-1, and Proinflammatory Cytokine Gene Expression in Metastatic Lung Tissue

Biophytum sensitivum is a traditional oriental herbal medicine that is known for its immunostimulatory and antitumor effects. Tumor metastasis is the most important cause of cancer death. Although B sensitivum was shown to inhibit metastasis, the mechanism underlying this action is not well understood. In the present report, the authors had studied the effect of B sensitivum on the invasion and motility of B16F-10 melanoma cells and investigate the regulatory effect on the expression of matrix metalloproteases (MMPs), prolyl hydoxylase, lysyl oxidase, nm23, extracellular signal-regulated kinase (ERK)—1, ERK-2, signal transducer and activator of transcription (STAT)—1, and proinflammatory cytokines in metastatic tumor-bearing lungs. B sensitivum inhibited the invasion and motility of B16F-10 cells in a dose-dependent manner. B sensitivum inhibited the expression of MMP-2 and MMP-9, whereas it activated STAT-1 expression in metastatic tumor-bearing lungs. Similarly, inhibition of prolyl hydroxylase, lysyl oxidase, ERK-1, ERK-2, and vascular endothelial growth factor (VEGF) expression but activation of nm23 by B sensitivum was observed in metastatic tumor-bearing lungs. B sensitivum treatment also downregulated the expression of tumor necrosis factor—α, interleukin (IL)—1β, IL-6, and granulocyte monocyte—colony stimulating factor in metastatic tumor-bearing lungs. In B16F-10 cells, B sensitivum also inhibited the production of proinflammatory cytokines. Overall, the results indicate that B sensitivum exhibits antimetastatic effects through the inhibition of invasion and motility. The results also suggest that MMPs, prolyl hydroxylase, lysyl oxidase, nm23, ERKs, VEGF, STAT, and proinflammatory cytokines are critical regulators of the B sensitivum—mediated antimetastatic effect.

Interaction between Cancer Cells and Stromal Fibroblasts Is Required for Activation of the uPAR-uPA-MMP-2 Cascade in Pancreatic Cancer Metastasis

PURPOSE

Interaction between tumor cells and surrounding stromal fibroblast (SF) plays a critical role in tumor growth and invasion. The aim of the study is to determine the role of SF in regulating the invasive behaviors of pancreatic cancer by evaluating the mode of SF activating the urokinase plasminogen activator (uPA)-plasmin-matrix metalloproteinase (MMP)-2 cascade.

EXPERIMENTAL DESIGN

The expression patterns of uPA, MMP-2, and uPA receptor (uPAR) in human metastatic pancreatic cancer were analyzed by immunohistochemistry and the roles of SF in activation of the uPA-plasmin-MMP-2 cascade were evaluated by coculturing pancreatic cancer cell lines with SF.

RESULTS

uPA expression and fibroblastic uPAR expression were correlated with liver metastasis of human pancreatic cancer. MMP-2 rather than MMP-9 was activated in the metastatic pancreatic cancer. In the in vitro culture system, the coculture of peritumor fibroblasts with metastatic pancreatic cancer BxPc3 cells resulted in activation of MMP-2 and up-regulation of uPAR expression. In this coculture system, the uPA-plasminogen cascade was involved in MMP-2 activation. This activation required a direct interaction between SF and cancer cells. In the coculture system, intergrin alpha(6)beta(1) expression was increased in BxPc3 cells, and blocking the function of integrin alpha(6)beta(1) decreased the activation of uPA and MMP-2. This suggests that interaction between integrins of cancer cells and the uPARs of the SF might be involved in the activation of the uPAR-uPA-MMP-2 cascade.

CONCLUSION

Our results suggest that SF plays a role in promoting pancreatic cancer metastasis via activation of the uPA-plasminogen-MMP-2 cascade.

Suppression of N-nitrosobis(2-oxopropyl)amine-induced pancreatic carcinogenesis in hamsters by pioglitazone, a ligand of peroxisome proliferator-activated receptor γ

Fat intake and obesity are positively correlated with pancreatic cancer in humans. N-nitrosobis(2-oxopropyl)amine (BOP) induces pancreatic ductal adenocarcinomas limited to Syrian golden hamsters, other rodents not being susceptible. In the present study, we found markedly high levels of serum triglycerides (TGs) and total cholesterol (TC) in Syrian golden hamsters, but not C57BL/6 mice, ICR mice, F344 rats and Wistar rats. Consistent with this, lipoprotein lipase (LPL) activities in the liver were lower in hamsters compared with mice and rats. To examine effects of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, on LPL expression, serum lipid levels and pancreatic cancer development, 6-week-old female Syrian golden hamsters were subcutaneously injected with BOP (10 mg/kg body wt) four times in a week and thereafter fed a diet containing 800 p.p.m. pioglitazone for 22 weeks. The treatment elevated LPL mRNA expression in the liver and significantly improved hyperlipidemia with serum levels of TG and TC being decreased to 62 and 71%, respectively, of the control values. Concurrently, the incidence and multiplicity of pancreatic ductal adenocarcinomas were significantly decreased by pioglitazone in comparison with the controls (38 versus 80%, P < 0.01 and 0.55 +/- 0.15 versus 1.37 +/- 0.22, P < 0.01, respectively). The suppression rates were greater in invasive adenocarcinomas than non-invasive ones. The incidence of cholangiocellular carcinomas was also reduced. Thus, suppression of pancreatic adenocarcinoma development by pioglitazone is possibly associated with improvement in the serum lipid profile, and hyperlipidemia could be an enhancing factor for development of pancreatic cancer in hamsters.