Biochemical role of the collagen-rich tumour microenvironment in pancreatic cancer progression. Biochem J. 2012;441:541-552. [PMID: 22187935 DOI: 10.1042/bj20111240]

Matrix metalloproteinase-14 is a negative prognostic marker for patients with gastric cancer

BACKGROUND

Matrix metalloproteinase-14 (MMP-14) has been considered to play an important role in invasion and metastasis of human solid tumor.

AIM

The present study aimed to investigate the association of MMP-14 with overall survival in human gastric cancer.

METHODS

Gastric cancer and adjacent normal specimens were collected from 205 patients who had not received neoadjuvant chemotherapy. MMP-14 expression was investigated by immunohistochemistry assay and staining evaluation results were analyzed statistically in relation to overall survival of patients.

RESULTS

MMP-14 expression proved to be increased in gastric cancer compared with that in normal tissues. It was also proved that MMP-14 expression was associated with tumor invasion, metastasis, and TNM stage while no correlations were detected between MMP-14 expression and age, sex, differentiation status, or Lauren's classification. Moreover, patients with gastric cancer of MMP-14-positive expression tend to have worse overall survival compared with those with MMP-14 negative expression.

CONCLUSIONS

The present study confirmed the over-expression of MMP-14 in human gastric cancer and its association with tumor progression. It also provided the first evidence that MMP-14 expression in gastric cancer was an independent negative prognostic factor of patients.

Inhibition of endotrophin, a cleavage product of collagen VI, confers cisplatin sensitivity to tumours

Endotrophin is a cleavage product of collagenVIα3 (COL6A3). Here, we explore the relationship between thiazolidinediones (TZDs), endotrophin and cisplatin resistance in the context of a mammary tumour model. COL6A3 levels are increased in response to cisplatin exposure in tumours. Endotrophin, in turn, causes cisplatin resistance. The effects of endotrophin can be bypassed, either through use of COL6 null (COL6^−/−) mice or by administering TZDs in wild-type mice (leading to a downregulation of endotrophin). Both approaches sensitize tumours to cisplatin through the suppression of endotrophin-induced epithelial–mesenchymal transition. The beneficial effects of TZDs on cisplatin sensitivity are diminished in COL6^−/− mice, whereas endotrophin⁺ tumours are sensitive to the TZD/cisplatin combination. Therefore, the chemosensitization obtained with TZDs is achieved through a downregulation of endotrophin. Treatment with an endotrophin neutralizing antibody in combination with cisplatin completely inhibits tumour growth of tumour allografts. Combined, our data suggest that endotrophin levels are a strong prognostic marker for the effectiveness of the combination therapy of TZDs with cisplatin, and neutralization of endotrophin activity dramatically improves the therapeutic response to combination therapy.

The influence of matrix properties on growth and morphogenesis of human pancreatic ductal epithelial cells in 3D

A highly tunable synthetic biomimetic hydrogel platform was developed to study the growth and morphogenesis of pancreatic ductal epithelial cells (PDEC) under the influence of a myriad of instructive cues. A PDEC line, PANC-1, was used as a model system to illustrate the importance of matrix compositions on cell fate determination. PANC-1 is an immortalized ductal epithelial cell line widely used in the study of pancreatic tumor cell behaviors. PANC-1 cells are also increasingly explored as a potential cell source for endocrine differentiation. Thus far, most studies related to PANC-1, among other PDEC lines, are performed on 2D culture surfaces. Here, we evaluated the effect of matrix compositions on PANC-1 cell growth and morphogenesis in 3D. Specifically, PANC-1 cells were encapsulated in PEG-based hydrogels prepared by step-growth thiol-ene photopolymerization. It was found that thiol-ene hydrogels provided a cytocompatible environment for encapsulation and 3D culture of PANC-1 cells. In contrast to a monolayer morphology on 2D culture surfaces, PANC-1 cells formed clusters in 3D thiol-ene hydrogels within 4 days of culture. After culturing for 10 days, however, the growth and structures of these clusters were significantly impacted by gel matrix properties, including sensitivity of the matrix to proteases, stiffness of the matrix, and ECM-mimetic motifs. The use of matrix metalloproteinase (MMP) sensitive linker or the immobilization of fibronectin-derived RGDS ligand in the matrix promoted PANC-1 cell growth and encouraged them to adopt ductal cyst-like structures. On the other hand, the encapsulated cells formed smaller and more compact aggregates in non-MMP responsive gels. The incorporation of laminin-derived YIGSR peptide did not enhance cell growth and caused the cells to form compact aggregates. Immobilized YIGSR also enhanced the expression of epithelial cell markers including β-catenin and E-cadherin. These studies have established PEG-peptide hydrogels formed by thiol-ene photo-click reaction as a suitable platform for studying and manipulating pancreatic epithelial cell growth and morphogenesis in 3D.

Triggering the landslide: The tumor-promotional effects of myofibroblasts

Cancers become significantly more dangerous when the tumor progresses from in situ, or contained, to an invasive state, in which the cancer cells acquire the ability to pass through the surrounding basement membrane (BM), a specialized extracellular matrix (ECM) that provides structure and contextual information to the underlying tissue. While the majority of tumors are carcinomas, derived from epithelial cells, it is the stromal cells surrounding the epithelial-derived tumor cells, including fibroblasts and myofibroblasts, vasculature, and immune cells, that are largely responsible for the production and remodeling of the ECM. Here, we will discuss myofibroblasts as key effectors of tumor progression, focusing on recent advances in breast and pancreatic carcinoma, showing how myofibroblasts may function properly in normal tissue remodeling and wound-healing processes, how in the tumor context they can drive cancer invasion and metastasis, and how the pathogenic functions of myofibroblasts may be targeted therapeutically.

Mechanistic insights into self-reinforcing processes driving abnormal histogenesis during the development of pancreatic cancer

Pancreatic ductal adenocarcinoma, one of the most feared lethal and painful diseases, is increasing in incidence. The poor prognosis of pancreatic ductal adenocarcinoma-affected patients primarily is owing to our inability to develop effective therapies. Mechanistic studies of genetic, epigenetic, and cell-to-cell signaling events are providing clues to molecular pathways that can be targeted in an attempt to cure this disease. The current review article seeks to draw inferences from available mechanistic knowledge to build a theoretical framework that can facilitate these approaches. This conceptual model considers pancreatic cancer as a tissue disease rather than an isolated epithelial cell problem, which develops and progresses in large part as a result of three positive feedback loops: i) genetic and epigenetic changes in epithelial cells modulate their interaction with mesenchymal cells to generate a dynamically changing process of abnormal histogenesis, which drives more changes; ii) the faulty tissue architecture of neoplastic lesions results in unsynchronized secretion of signaling molecules by cells, which generates an environment that is poor in oxygen and nutrients; and iii) the increased metabolic needs of rapidly dividing cells serve as an evolutionary pressure for them to adapt to this adverse microenvironment, leading to the emergence of resistant clones. We discuss how these concepts can guide mechanistic studies, as well as aid in the design of novel experimental therapeutics.

Peroxisome proliferator-activated receptor gamma and regulations by the ubiquitin-proteasome system in pancreatic cancer

Pancreatic cancer is one of the most lethal forms of human cancer. Although progress in oncology has improved outcomes in many forms of cancer, little progress has been made in pancreatic carcinoma and the prognosis of this malignancy remains grim. Several molecular abnormalities often present in pancreatic cancer have been defined and include mutations in K-ras, p53, p16, and DPC4 genes. Nuclear receptor Peroxisome Proliferator-Activated Receptor gamma (PPARγ) has a role in many carcinomas and has been found to be overexpressed in pancreatic cancer. It plays generally a tumor suppressor role antagonizing proteins promoting carcinogenesis such as NF-κB and TGFβ. Regulation of pathways involved in pancreatic carcinogenesis is effectuated by the Ubiquitin Proteasome System (UPS). This paper will examine PPARγ in pancreatic cancer, the regulation of this nuclear receptor by the UPS, and their relationship to other pathways important in pancreatic carcinogenesis.

Involvement of host stroma cells and tissue fibrosis in pancreatic tumor development in transgenic mice

Introduction

Stroma cells and extracellular matrix (ECM) components provide the pivotal microenvironment for tumor development. The study aimed to evaluate the importance of the pancreatic stroma for tumor development.

Methods

Pancreatic tumor cells were implanted subcutaneously into green fluorescent protein transgenic mice, and stroma cells invading the tumors were identified through immunohistochemistry. Inhibition of tumor invasion by stroma cells was achieved with halofuginone, an inhibitor of TGFβ/Smad3 signaling, alone or in combination with chemotherapy. The origin of tumor ECM was evaluated with species-specific collagen I antibodies and in situ hybridization of collagen α1(I) gene. Pancreatic fibrosis was induced by cerulean injection and tumors by spleen injection of pancreatic tumor cells.

Results

Inhibition of stroma cell infiltration and reduction of tumor ECM levels by halofuginone inhibited development of tumors derived from mouse and human pancreatic cancer cells. Halofuginone reduced the number only of stroma myofibroblasts expressing both contractile and collagen biosynthesis markers. Both stroma myofibroblasts and tumor cells generated ECM that contributes to tumor growth. Combination of treatments that inhibit stroma cell infiltration, cause apoptosis of myofibroblasts and inhibit Smad3 phosphorylation, with chemotherapy that increases tumor-cell apoptosis without affecting Smad3 phosphorylation was more efficacious than either treatment alone. More tumors developed in fibrotic than in normal pancreas, and prevention of tissue fibrosis greatly reduced tumor development.

Conclusions

The utmost importance of tissue fibrosis and of stroma cells for tumor development presents potential new therapy targets, suggesting combination therapy against stroma and neoplastic cells as a treatment of choice.

The extracellular matrix and ciliary signaling

The primary cilium protrudes like an antenna from the cell surface, sensing mechanical and chemical cues provided in the cellular environment. In some tissue types, ciliary orientation to lumens allows response to fluid flow; in others, such as bone, ciliary protrusion into the extracellular matrix allows response to compression forces. The ciliary membrane contains receptors for Hedgehog, Wnt, Notch, and other potent growth factors, and in some instances also harbors integrin and cadherin family members, allowing receipt of a robust range of signals. A growing list of ciliopathies, arising from deficient formation or function of cilia, includes both developmental defects and chronic, progressive disorders such as polycystic kidney disease (PKD); changes in ciliary function have been proposed to support cancer progression. Recent findings have revealed extensive signaling dialog between cilia and extracellular matrix (ECM), with defects in cilia associated with fibrosis in multiple contexts. Further, a growing number of proteins have been determined to possess multiple roles in control of cilia and focal adhesion interactions with the ECM, further coordinating functionality. We summarize and discuss these recent findings.

T cell immunoglobulin- and mucin-domain-containing molecule 3 gene polymorphisms and susceptibility to pancreatic cancer

T cell immunoglobulin- and mucin-domain-containing molecule 3 (TIM-3) is a novel transmembrane protein that is involved in the regulation of T-helper 1 cell-mediated immunity. Studies have shown that polymorphisms in TIM-3 gene can be associated with various diseases. Here, we investigated the correlation of TIM-3 polymorphisms with susceptibility to pancreatic cancer in the Chinese population. Three polymorphisms in TIM-3 gene (-1516G/T, -574G/T, and +4259T/G) were identified by polymerase chain reaction-restriction fragment length polymorphism in 306 pancreatic patients and 408 healthy controls. Results showed that the prevalence of +4259TG genotype and +4259G allele were significantly increased in the pancreatic cancer cases than in controls [odds ratio (OR) = 2.82, 95 % confidence interval (CI), 1.45-5.48, p = 0.0015, and OR = 2.74, 95 % CI, 1.42-2.94, p = 0.0017]. In addition, when analyzing the TIM-3 polymorphisms with different clinical parameters in pancreatic cancer patients, the cases with vascular infiltration had higher numbers of +4259T/G polymorphism than those without vascular infiltration (OR = 3.07, 95 % CI, 1.41-6.68, p = 0.003). These results suggested polymorphisms in TIM-3 gene could be new risk factors for the development of pancreatic cancer.

Interplay between β1-integrin and Rho signaling regulates differential scattering and motility of pancreatic cancer cells by snail and Slug proteins

The Snail family of transcription factors has been implicated in pancreatic cancer progression. We recently showed that Snail (Snai1) promotes membrane-type 1 matrix metalloproteinase (MT1-MMP)- and ERK1/2-dependent scattering of pancreatic cancer cells in three-dimensional type I collagen. In this study, we examine the role of Slug (Snai2) in regulating pancreatic cancer cell scattering in three-dimensional type I collagen. Although Slug increased MT1-MMP expression and ERK1/2 activity, Slug-expressing cells failed to scatter in three-dimensional collagen. Moreover, in contrast to Snail-expressing cells, Slug-expressing cells did not demonstrate increased collagen I binding, collagen I-driven motility, or α2β1-integrin expression. Significantly, inhibiting β1-integrin function decreased migration and scattering of Snail-expressing cells in three-dimensional collagen. As Rho GTPases have been implicated in invasion and migration, we also analyzed the contribution of Rac1 and Rho signaling to the differential migration and scattering of pancreatic cancer cells. Snail-induced migration and scattering were attenuated by Rac1 inhibition. In contrast, inhibiting Rho-associated kinase ROCK1/2 increased migration and scattering of Slug-expressing cells in three-dimensional collagen and thus phenocopied the effects of Snail in pancreatic cancer cells. Additionally, the increased migration and scattering in three-dimensional collagen of Slug-expressing cells following ROCK1/2 inhibition was dependent on β1-integrin function. Overall, these results demonstrate differential effects of Snail and Slug in pancreatic cancer and identify the interplay between Rho signaling and β1-integrin that functions to regulate the differential scattering and migration of Snail- and Slug-expressing pancreatic cancer cells.