Periostin creates a tumor-supportive microenvironment in the pancreas by sustaining fibrogenic stellate cell activity

TGFβ3-mediated induction of Periostin facilitates head and neck cancer growth and is associated with metastasis

The matrix-specific protein periostin (POSTN) is up-regulated in human cancers and associated with cancer growth, metastasis and angiogenesis. Although the stroma of cancer tissues is the main source of POSTN, it is still unclear how POSTN plays a role to facilitate the interplay between cancer cells and cancer-associated fibroblasts (CAFs) in head and neck cancer (HNC), thereby promoting tumorigenesis via modifying the tumor microenvironment. Herein, we have performed studies to investigate POSTN and its role in HNC microenvironment. Our results indicated that POSTN was significantly up-regulated in HNCs, especially in the tissues with lymph node metastasis. Moreover, POSTN was highly enriched in the stroma of cancer tissues and produced mainly by CAFs. More importantly, we have pinpointed TGF-β3 as the major upstream molecular that triggers the induction of POSTN in CAFs. As such, during the interaction between fibroblasts and cancer cells, the increased stromal POSTN induced by TGF-β3 directly accelerated the growth, migration and invasion of cancer cells. Hence, our study has provided a novel modulative role for POSTN on HNC progression and further reveals POSTN as an effective biomarker to predict metastasis as well as a potential cancer therapeutic target.

CT Imaging Biomarkers Predict Clinical Outcomes After Pancreatic Cancer Surgery

This study aimed to determine whether changes in contrast-enhanced computed tomography (CT) parameters could predict postsurgery overall and progression-free survival (PFS) in pancreatic cancer patients. Seventy-nine patients with a final pathological diagnosis of pancreatic adenocarcinoma were included in this study from June 2008 to August 2012. Dynamic contrast-enhanced (DCE) CT of tumors was obtained before curative-intent surgery. Absolute enhancement change (AEC) and relative enhancement change (REC) were evaluated on DCE-CT. PFS and overall survival (OS) were compared based on CT enhancement patterns. The markers of fibrogenic alpha-smooth muscle antigen (α-SMA) and periostin in tumor specimens were evaluated by immunohistochemical staining. The χ test was performed to determine whether CT enhancement patterns were associated with α-SMA-periostin expression levels (recorded as positive or negative). Lower REC (<0.9) was associated with shorter PFS (HR 0.51, 95% CI: 0.31-0.89) and OS (HR 0.44, 95% CI: 0.25-0.78). The α-SMA and periostin expression level were negatively correlated with REC (both P = 0). Among several CT enhancement parameters, REC was the best predictor of patient postsurgery survival. Low REC was associated with a short progression-free time and poor survival. The pathological studies suggested that REC might be a reflection of cancer fibrogenic potential.

Role of Periostin in Adhesion and Migration of Bone Remodeling Cells

Periostin is an extracellular matrix protein highly expressed in collagen-rich tissues subjected to continuous mechanical stress. Functionally, periostin is involved in tissue remodeling and its altered function is associated to numerous pathological processes. In orthodontics, periostin plays key roles in the maintenance of dental tissues and it is mainly expressed in those areas where tension or pressing forces are taking place. In this regard, high expression of periostin is essential to promote migration and proliferation of periodontal ligament fibroblasts. However little is known about the participation of periostin in migration and adhesion processes of bone remodeling cells. In this work we employ the mouse pre-osteoblastic MC3T3-E1 and the macrophage-like RAW 264.7 cell lines to overexpress periostin and perform different cell-based assays to study changes in cell behavior. Our data indicate that periostin overexpression not only increases adhesion capacity of MC3T3-E1 cells to different matrix proteins but also hampers their migratory capacity. Changes on RNA expression profile of MC3T3-E1 cells upon periostin overexpression have been also analyzed, highlighting the alteration of genes implicated in processes such as cell migration, adhesion or bone metabolism but not in bone differentiation. Overall, our work provides new evidence on the impact of periostin in osteoblasts physiology.

Clinical Insights Into the Biology and Treatment of Pancreatic Cancer

Pancreatic cancer is a devastating disease with a universally poor prognosis. In 2015, it is estimated that there will be 48,960 new cases of pancreatic cancer and that 40,560 people will die of the disease. The 5-year survival rate is 7.2% for all patients with pancreatic cancer; however, survival depends greatly on the stage at diagnosis. Unfortunately, 53% of patients already have metastatic disease at diagnosis, which corresponds to a 5-year survival rate of 2.4%. Even for the 9% of patients with localized disease confined to the pancreas, the 5-year survival is still modest at only 27.1%. These grim statistics highlight the need for ways to identify cohorts of individuals at highest risk, methods to screen those at highest risk to identify preinvasive pathologic precursors, and development of effective systemic therapies. Recent clinical and translational progress has emphasized the relationship with diabetes, the role of the stroma, and the interplay of each of these with inflammation in the pathobiology of pancreatic cancer. In this article, we will discuss these relationships and how they might translate into novel management strategies for the treatment of this disease.

Nicotine Reduces Survival via Augmentation of Paracrine HGF-MET Signaling in the Pancreatic Cancer Microenvironment

PURPOSE

The relationship between smoking and pancreatic cancer biology, particularly in the context of the heterogeneous microenvironment, remains incompletely defined. We hypothesized that nicotine exposure would lead to the augmentation of paracrine growth factor signaling between tumor-associated stroma (TAS) and pancreatic cancer cells, ultimately resulting in accelerated tumor growth and metastasis.

EXPERIMENTAL DESIGN

The effect of tobacco use on overall survival was analyzed using a prospectively maintained database of surgically resected patients with pancreatic cancer. Nicotine exposure was evaluated in vitro using primary patient-derived TAS and pancreatic cancer cells independently and in coculture. Nicotine administration was then assessed in vivo using a patient-derived pancreatic cancer xenograft model.

RESULTS

Continued smoking was associated with reduced overall survival after surgical resection. In culture, nicotine-stimulated hepatocyte growth factor (HGF) secretion in primary patient-derived TAS and nicotine stimulation was required for persistent pancreatic cancer cell c-Met activation in a coculture model. c-Met activation in this manner led to the induction of inhibitor of differentiation-1 (Id1) in pancreatic cancer cells, previously established as a mediator of growth, invasion and chemoresistance. HGF-induced Id1 expression was abrogated by both epigenetic and pharmacologic c-Met inhibition. In patient-derived pancreatic cancer xenografts, nicotine treatment augmented tumor growth and metastasis; tumor lysates from nicotine-treated mice demonstrated elevated HGF expression by qRT-PCR and phospho-Met levels by ELISA. Similarly, elevated levels of phospho-Met in surgically resected pancreatic cancer specimens correlated with reduced overall survival.

CONCLUSIONS

Taken together, these data demonstrate a novel, microenvironment-dependent paracrine signaling mechanism by which nicotine exposure promotes the growth and metastasis of pancreatic cancer.

Key role of pancreatic stellate cells in pancreatic cancer

Pancreatic stellate cells (PSCs) are responsible for producing the collagenous stroma in pancreatic cancer. Findings from the majority of in vitro and in vivo studies to date indicate that PSCs interact with cancer cells as well as with other cellular elements in the stroma including immune cells, endothelial cells and neuronal cells to set up a growth permissive microenvironment for pancreatic tumours. However, two recent studies reporting a protective effect of myofibroblasts in pancreatic cancer have served to remind researchers of the possibility that the role of PSCs in this disease may be context and time-dependent, such that any possible early protective role of PSCs is subverted in later stages by the ability of cancer cells to turn PSCs into cancer-promoting aides. This concept is supported by the development in recent years of several novel therapeutic approaches targeting the stroma that have been successfully applied in pre-clinical settings to inhibit disease progression. A multi-pronged approach aimed at tumour cells as well as stromal elements may be the key to achieving better clinical outcomes in patients with pancreatic cancer.

Primary outgrowth cultures are a reliable source of human pancreatic stellate cells

Recent advances demonstrate a critical yet poorly understood role for the pancreatic stellate cell (PSC) in the pathogenesis of chronic pancreatitis (CP) and pancreatic cancer (PC). Progress in this area has been hampered by the availability, fidelity, and/or reliability of in vitro models of PSCs. We examined whether outgrowth cultures from human surgical specimens exhibited reproducible phenotypic and functional characteristics of PSCs. PSCs were cultured from surgical specimens of healthy pancreas, CP and PC. Growth dynamics, phenotypic characteristics, soluble mediator secretion profiles and co-culture with PC cells both in vitro and in vivo were assessed. Forty-seven primary cultures were established from 52 attempts, demonstrating universal α-smooth muscle actin and glial fibrillary acidic protein but negligible epithelial surface antigen expression. Modification of culture conditions consistently led to cytoplasmic lipid accumulation, suggesting induction of a quiescent phenotype. Secretion of growth factors, chemokines and cytokines did not significantly differ between donor pathologies, but did evolve over time in culture. Co-culture of PSCs with established PC cell lines resulted in significant changes in levels of multiple secreted mediators. Primary PSCs co-inoculated with PC cells in a xenograft model led to augmented tumor growth and metastasis. Therefore, regardless of donor pathology, outgrowth cultures produce PSCs that demonstrate consistent growth and protein secretion properties. Primary cultures from pancreatic surgical specimens, including malignancies, may represent a reliable source of human PSCs.

Potent antitumor effect of neurotensin receptor-targeted oncolytic adenovirus co-expressing decorin and Wnt antagonist in an orthotopic pancreatic tumor model

Pancreatic cancer is highly aggressive, malignant, and notoriously difficult to cure using conventional cancer therapies. These conventional therapies have significant limitations due to excessive extracellular matrix (ECM) of pancreatic cancer and poor cancer specificity. The excess ECM prevents infiltration of drugs into the inner layer of the solid tumor. Therefore, novel treatment modalities that can specifically target the tumor and degrade the ECM are required for effective therapy. In the present study, we used ECM-degrading and Wnt signal-disrupting oncolytic adenovirus (oAd/DCN/LRP) to achieve a desirable therapeutic outcome against pancreatic cancer. In addition, to overcome the limitations in systemic delivery of oncolytic Ad (oAd) and to specifically target pancreatic cancer, neurotensin peptide (NT)-conjugated polyethylene glycol (PEG) was chemically crosslinked to the surface of Ad, generating a systemically injectable hybrid system, oAd/DCN/LRP-PEG-NT. We tested the targeting and therapeutic efficacy of oAd/DCN/LRP-PEG-NT toward neurotensin receptor 1 (NTR)-overexpressing pancreatic cancer cells, both in vitro and in vivo. The oAd/DCN/LRP-PEG-NT elicited increased NTR-selective cancer cell killing and transduction efficiency when compared with a cognate control lacking NT (oAd/DCN/LRP-PEG). Furthermore, systemic administration of oAd/DCN/LRP-PEG-NT significantly decreased induction of innate and adaptive immune responses against Ad, and blood retention time was markedly prolonged by PEGylation. Moreover, NTR-targeting oAd elicited greater in vivo tumor growth suppression when compared with naked oAd and 9.5 × 10(6)-fold increased tumor-to-liver ratio. This significantly enhanced antitumor effect of oAd/DCN/LRP-PEG-NT was mediated by active viral replication and viral spreading, which was facilitated by ECM degradation and inhibition of Wnt signaling-related factors (Wnt, β-catenin, and/or vimentin) in the tumor tissues. Taken together, these results demonstrate that oAd/DCN/LRP-PEG-NT has strong therapeutic potential for systemic treatment of NTR-overexpressing pancreatic cancer due to its NTR-targeting ability, enhanced therapeutic efficacy, and safety.

Biomarkers and severe asthma: a critical appraisal

Severe asthma (SA) is a clinically and etiologically heterogeneous respiratory disease which affects among 5–10 % of asthmatic patients. Despite high-dose therapy, a large patients percentage is not fully controlled and has a poor quality of life. In this review, we describe the biomarkers actually known in scientific literature and used in clinical practice for SA assessment and management: neutrophils, eosinophils, periostin, fractional exhaled nitric oxide, exhaled breath condensate and galectins. Moreover, we give an overview on clinical and biological features characterizing severe asthma, paying special attention to the potential use of these ones as reliable markers. We finally underline the need to define different biomarkers panels to select patients affected by severe asthma for specific and personalized therapeutic approach.

[Metastasis of pancreatic tumors]

With a 5-year survival rate that has remained stagnant at 6 % for decades, pancreatic ductal adenocarcinoma (PDAC) is still one of the most fatal malignancies. Despite intensive research, currently available therapy options are less than adequate. As more than half of the patients already show distant metastases at the time of diagnosis, metastatic disease should be a primary focus in the development of new therapeutic strategies. New findings from basic research provide various interesting approaches: molecular profiling of the primary tumor seems to be a possible method to gain knowledge about the prognosis, metastatic potential and therapy response of each individual case of PDAC. Certain subpopulations of cancer stem cells also seem to be of importance in metastasis of PDAC and could become potential therapeutic targets in the future. Interactions between tumor cells and their microenvironment are another crucial factor in the metastasis of pancreatic cancer and present various new starting points for potential therapies. As the number of cell types and signaling pathways that are found to play a role in PDAC metastasis continue to grow, the next big challenge will be to translate these findings into viable clinical applications.

Pancreatic stellate cells: A dynamic player of the intercellular communication in pancreatic cancer

There is accumulating evidence that activated pancreatic stellate cells (PSCs) play a pivotal role in the development of pancreatic fibrosis within the pancreatic cancer tissue. Not only do they produce extracellular matrix components, PSCs dynamically interact with other cell types to constitute the cancer-conditioned microenvironment. There exist bidirectional interactions between PSCs and pancreatic cancer cells. Pancreatic cancer cells promote the proliferation, migration, extracellular matrix production and degradation, and angiogenetic responses in PSCs. In turn, PSCs promote the proliferation and migration, and inhibit the apoptosis of pancreatic cancer cells. PSCs also induce epithelial-mesenchymal transition and stem cell like phenotypes in pancreatic cancer cells, resulting in resistance to conventional therapies, distant metastasis, and recurrence. PSCs interact with endothelial cells, neural cells and β-cells, leading to angiogenesis, neurogenesis and β-cell dysfunction and apoptosis. PSCs cause impaired immune responses and help pancreatic cancer cells escape from host immune-surveillance. PSCs induce the differentiation of myeloid-derived suppressor cells, induce the apoptosis of T cells, inhibit the infiltration of T cells, and induce the activation of mast cells. Overall, these interactions appear to promote the progression of pancreatic cancer, and anti-stroma therapies targeting PSCs are under intense investigation. Further elucidation of these interactions could lead to the identification of novel therapeutic targets in pancreatic cancer.

Pancreatic cancer: The microenvironment needs attention too!

The abundant stromal/desmoplastic reaction, a characteristic feature of a majority of pancreatic adenocarcinomas (PDAC), has only recently been receiving some attention regarding its possible role in the pathobiology of pancreatic cancer. It is now well established that the cells predominantly responsible for producing the collagenous stroma are pancreatic stellate cells (PSCs). In addition to extracellular matrix proteins, the stroma also exhibits cellular elements including, immune cells, endothelial cells and neural cells. Evidence is accumulating to indicate the presence of significant interactions between PSCs and cancer cells as well as between PSCs and other cell types in the stroma. The majority of research reports to date, using in vitro and in vivo approaches, suggest that these interactions facilitate local growth as well as distant metastasis of pancreatic cancer, although a recent study using animals depleted of myofibroblasts has raised some questions regarding the central role of myofibroblasts in cancer progression. Nonetheless, novel therapeutic strategies have been assessed, mainly in the pre-clinical setting, in a bid to interrupt stromal-tumour interactions and inhibit disease progression. The next important challenge is for the translation of such pre-clinical strategies to the clinical situation so as to improve the outcome of patients with pancreatic cancer.

What are the macrophages and stellate cells doing in pancreatic adenocarcinoma?

Pancreatic ductal adenocarcinoma is a devastating disease characterized by a dense desmoplastic stroma. Chemo- and radio-therapeutic strategies based on targeting cancer cells have failed in improving the outcome of this cancer suggesting important roles for stroma in therapy resistance. Cells in the tumor stroma have been shown to regulate proliferation, resistance to apoptosis and treatments, epithelial to mesenchymal transition (EMT) and stemness of cancer cells. Stellate cells in their activated state have been thought over the past decade to only have tumor promoting roles. However, recent findings suggest that stellate cells may have protective roles as well. The present review highlights the latest findings on the role of two major components of tumor stroma, pancreatic stellate cells and macrophages, in promoting or inhibiting pancreatic cancer, focused on their effects on EMT and cancer stemness.

Role of pancreatic stellate cells and periostin in pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and one of the five most lethal malignancies characterized by prominent desmoplastic reaction. Accumulating evidences indicate that tumor desmoplasia plays a pivotal role in PDAC progression, and it has been largely ignored until recent times. It has now been unequivocally shown that pancreatic stellate cells (PSCs) are the principal effector cells responsible for stroma production. Periostin, also known as osteoblast-specific factor 2, is a secretory protein and originally identified as an osteoblast-specific factor that expressed in periosteum. Periostin is exclusively produced by activated PSCs, and periostin overexpression presents in various malignant tumors and closely relates with disease progression. In addition, periostin has been suggested to stimulate pancreatic cancer cells proliferation and enhance their resistance to serum starvation and hypoxia. Therefore, the interplay between cancer cells and stromal cells plays a vital role in PDAC development. However, the function of periostin in pancreatic cancer development is controversial. This review summarizes existing knowledge about the role of PSCs in cancer stroma production, the interaction between PSCs and pancreatic cancer cells, tumor angiogenesis, and hypoxic microenvironment, with particular focus on the expression and function as well as signaling pathways of periostin in PDAC cells and PSCs.

Kif20a inhibition reduces migration and invasion of pancreatic cancer cells

BACKGROUND

The Translational Genome Research Network in Pancreatic Cancer performed a meta-analysis of publicly available various high-throughput gene analysis panels to identify drugable targets. There, the most differentially expressed gene between normal and cancerous pancreas was Kif20a. The aim of the study was to verify this expression pattern and further characterize Kif20a in pancreatic cancer.

MATERIALS AND METHODS

Detailed expression analyses were carried out in pancreatic tissues and in a wide panel of pancreatic cells including ductal adenocarcinoma (PDAC) and neuroendocrine-cancer cell lines as well as immortalized human pancreatic ductal epithelial and primary stellate cells using quantitative real-time polymerase chain reaction, immunohistochemistry, immunofluorescence, and immunoblot analyses. Effects on proliferation, apoptosis, and cell cycle were assessed by MTT assays, caspase-cleavage assays, and fluorescence-activated cell sorting analysis after Kif20a silencing. Cell motility was assessed by migration and invasion assays as well as time-lapse microscopy.

RESULTS

Mean Kif20a messenger RNA expression was 18.4-fold upregulated in PDAC tissues compared with that in the normal pancreas. In line, neuroendocrine-cancer cell lines display a 1.6-fold increase and ductal adenocarcinoma cell lines a 11-fold increase of Kif20a messenger RNA (P = 0.009) in comparison with primary stellate cells. A 7.3-fold overexpression was also found in immortalized pancreatic ductal epithelial cells. Kif20a silencing with small interfering RNA molecules resulted in an inhibition of proliferation, motility, and invasion of pancreatic cancer cell lines.

CONCLUSIONS

Targeting Kif20a reduces proliferation, migration, and invasion of pancreatic cancer cells. Together with its significant overexpression in PDAC, this makes it a potential target for diagnostic and interventional purposes.

Overexpression of periostin in stroma positively associated with aggressive prostate cancer

BACKGROUND

Periostin is an important extracellular matrix protein involved in cell development and adhesion. Previously, we identified periostin to be up-regulated in aggressive prostate cancer (CaP) using quantitative glycoproteomics and mass spectrometry. The expression of periostin was further evaluated in primary radical prostatectomy (RP) prostate tumors and adjacent non-tumorous prostate tissues using immunohistochemistry (IHC). Our IHC results revealed a low background periostin levels in the adjacent non-tumorous prostate tissues, but overexpressed periostin levels in the peritumoral stroma of primary CaP tumors.

METHODS

In this study, periostin expression in CaP was further examined on multiple tissue microarrays (TMAs), which were conducted in four laboratories. To achieve consistent staining, all TMAs were stained with same protocol and scored by same image computation tool to determine the total periostin staining intensities. The TMAs were further scored by pathologists to characterize the stromal staining and epithelial staining.

RESULTS

The periostin staining was observed mainly in peritumoral stromal cells and in some cases in tumor epithelial cells though the stronger staining was found in peritumoral stromal cells. Both periostin stromal staining and epithelial staining can differentiate BPH from CaP including low grade CaP (Gleason score ≤6), with significant p-value of 2.2e-16 and 0.001, respectively. Periostin epithelial staining differentiated PIN from low grade CaP (Gleason score ≤6) (p=0.001), while periostin stromal staining differentiated low grade Cap (Gleason score ≤6) from high grade Cap (Gleason score ≤6) (p=1.7e-05). In addition, a positive correlation between total periostin staining and Gleason score was observed (r=0.87, p=0.002).

CONCLUSIONS

The results showed that periostin staining was positively correlated with increasing Gleason score and the aggressiveness of prostate disease.

Role of periostin and its antagonist PNDA-3 in gastric cancer metastasis

The extracellular matrix component periostin is a secreted protein that functions as both a cell attachment protein and an autocrine or paracrine factor that signals through the cell adhesion molecule integrins α_vβ₃ and α_vβ₅. Periostin participates in normal physiological activities such as cardiac development, but is also involved in pathophysiological processes in vascular diseases, wound repair, bone formation, and tumor development. It is of increasing interest in tumor biology because it is frequently overexpressed in a variety of epithelial carcinomas and is functionally involved in multiple steps of metastasis progression. These include the maintenance of stemness, niche formation, EMT, the survival of tumor cells, and angiogenesis, all of which are indispensable for gastric cancer metastasis. Periostin has been reported to activate the PI-3K/AKT, Wnt, and FAK-mediated signaling pathways to promote metastasis. Therefore, periostin represents a potentially promising candidate for the inhibition of metastasis. In this review article, we summarize recent advances in knowledge concerning periostin, its antagonist PNDA-3, and their influence on such key processes in cancer metastasis as maintenance of stemness, niche formation, epithelial-to-mesenchymal transition, tumor cell survival, and angiogenesis. In particular, we focus our attention on the role of periostin in gastric cancer metastasis, speculate as to the usefulness of periostin as a therapeutic and diagnostic target for gastric cancer metastasis, and consider potential avenues for future research.

Periostin induces pancreatic regeneration

We found that the secreted protein periostin (Postn) is highly induced after partial pancreatectomy in regenerating areas containing mesenchymal stroma and tubular complexes. Importantly, after partial pancreatectomy, Postn-deficient mice exhibit impaired mesenchymal formation and reduced regeneration specifically within the pancreatic β-cell compartment. Furthermore, Postn-deficient mice demonstrate an increased sensitivity to streptozotocin. Notably, injection of Postn directly into the pancreas stimulated proliferation of vimentin-expressing cells within 24 hours, and by 3 days, a mesenchymal stroma was present containing proliferating duct-like cells expressing the progenitor markers Ngn3 and Pdx1. Intraperitoneal injection of Postn resulted in increased numbers of islets and long-term glucoregulatory benefits with no adverse effects found in other tissues. Delivery of Postn throughout the pancreas via the common bile duct resulted in increased numbers of small insulin-expressing clusters and a significant improvement in glucose tolerance. Therefore, Postn is novel molecule capable of potentiating pancreatic β-cell regeneration.

Unique expression pattern and functional role of periostin in human limbal stem cells

Periostin is a non-structural matricellular protein. Little is known about periostin in human limbal stem cells (LSCs). This study was to explore the unique expression pattern and functional role of periostin in maintaining the properties of human LSCs. Fresh donor corneal tissues were used to make cryosections for evaluation of periostin expression on ex vivo tissues. Primary human limbal epithelial cells (HLECs) were generated from limbal explant culture. In vitro culture models for proliferation and epithelial regeneration were performed to explore functional role of periostin in LSCs. The mRNA expression was determined by reverse transcription and quantitative real-time PCR (RT-qPCR), and the protein production and localization were detected by immunofluorescent staining and Western blot analysis. Periostin protein was found to be exclusively immunolocalized in the basal layer of human limbal epithelium. Periostin localization was well matched with nuclear factor p63, but not with corneal epithelial differentiation marker Keratin 3. Periostin transcripts was also highly expressed in limbal than corneal epithelium. In primary HLECs, periostin expression at mRNA and protein levels was significantly higher in 50% and 70% confluent cultures at exponential growth stage than in 100% confluent cultures at slow growth or quiescent condition. This expression pattern was similar to other stem/progenitor cell markers (p63, integrin β1 and TCF4). Periostin expression at transcripts, protein and immunoreactivity levels increased significantly during epithelial regeneration in wound healing process, especially in 16-24 hours at wound edge, which was accompanied by similar upregulation and activation of p63, integrin β1 and TCF4. Our findings demonstrated that periostin is exclusively produced by limbal basal epithelium and co-localized with p63, where limbal stem cells reside. Periostin promotes HLEC proliferation and regeneration with accompanied activation of stem/progenitor cell markers p63, integrin β1 and TCF4, suggesting its novel role in maintaining the phenotype and functional properties of LSC.

Periostin in intrahepatic cholangiocarcinoma: pathobiological insights and clinical implications

Periostin is a modular glycoprotein frequently observed to be a major constituent of the extracellular milieu of mass-forming intrahepatic cholangiocarcinoma and other desmoplastic malignant tumors. In intrahepatic cholangiocarcinoma, as well as in desmoplastic pancreatic ductal adenocarcinoma, periostin is overexpressed and hypersecreted in large part, if not exclusively, by cancer-associated fibroblasts within the tumor stroma. Through its interaction with specific components of the extracellular tumor matrix, particularly collagen type I and tenascin-C, and with cell surface receptors, notably integrins leading to activation of the Akt and FAK signaling pathways, this TGF-β family-inducible matricellular protein appears to be functioning as a key extracellular matrix molecule regulating such critically important and diverse malignant tumor behaviors as tumor fibrogenesis and desmoplasia, invasive malignant cell growth, chemoresistance, and metastatic colonization. This review will discuss current evidence and basic molecular mechanisms implicating periostin as a mediator of intrahepatic cholangiocarcinoma invasive growth. In addition, its significance as a potential prognostic biomarker for intrahepatic cholangiocarcinoma patients, as well as future possibilities and challenges as a molecular target for cholangiocarcinoma therapy and/or prevention, will be critically evaluated.

Perfusion in the tissue surrounding pancreatic cancer and the patient's prognosis

Objective. The objective was to investigate the relationship between prognosis in case of pancreatic cancer and perfusion in tissue surrounding pancreatic cancer using perfusion CT. Methods. We enrolled 17 patients diagnosed with inoperable pancreatic adenocarcinoma. All patients were examined by perfusion CT and then underwent chemotherapy using gemcitabine. The time density curve (TDC) of each CT pixel was analyzed to calculate area under the curve (AUC) and blood flow (BF) using a mathematical algorithm based on the single-compartment model. To measure the AUC and BF of tumor (AUC_T and BF_T) and peritumoral tissue (AUC_PTT and BF_PTT), regions of interest were manually placed on the cancer and in pancreatic tissue within 10 mm of proximal pancreatic parenchyma. Survival days from the date of perfusion CT were recorded. Correlation between AUC or BF and survival days was assessed. Results. We found a significant correlation between AUC_PTT or BF_PTT and survival days (P = 0.04 or 0.0005). Higher AUC_PTT or BF_PTT values were associated with shorter survival. We found no significant correlation between AUC_T or BF_T and survival. Conclusions. Our results suggest that assessments of perfusion in pancreatic tissue within 10 mm of proximal pancreatic parenchyma may be useful in predicting prognosis.

Pancreatic cancer and its stroma: A conspiracy theory

Pancreatic cancer is characterised by a prominent desmoplastic/stromal reaction that has received little attention until recent times. Given that treatments focusing on pancreatic cancer cells alone have failed to significantly improve patient outcome over many decades, research efforts have now moved to understanding the pathophysiology of the stromal reaction and its role in cancer progression. In this regard, our Group was the first to identify the cells (pancreatic stellate cells, PSCs) that produced the collagenous stroma of pancreatic cancer and to demonstrate that these cells interacted closely with cancer cells to facilitate local tumour growth and distant metastasis. Evidence is accumulating to indicate that stromal PSCs may also mediate angiogenesis, immune evasion and the well known resistance of pancreatic cancer to chemotherapy and radiotherapy. This review will summarise current knowledge regarding the critical role of pancreatic stellate cells and the stroma in pancreatic cancer biology and the therapeutic approaches being developed to target the stroma in a bid to improve the outcome of this devastating disease.

Investigation of Schwann cells at neoplastic cell sites before the onset of cancer invasion

BACKGROUND

In neural invasion (NI), cancer cells are classically assumed to actively invade nerves and to cause local recurrence and pain. However, the opposite possibility, that nerves may reach cancer cells even in their preinvasive stage and thereby promote cancer spread, has not yet been genuinely considered. The present study analyzes the reaction of Schwann cells of peripheral nerves to carcinogenesis in pancreatic cancer and colon cancer.

METHODS

Two novel 3D migration and Schwann cell outgrowth assays were developed to monitor the timing and the specificity of Schwann cell migration and cancer invasion toward peripheral neurons through digital-time-lapse microscopy and after blockade of nerve growth factor (NGF) signalling via siRNA or a small-molecule inhibitor of the p75(NTR) receptor. The frequency and emergence of the Schwann cell markers Sox10, S100, ALDH1L1, and glial-fibrillary-acidic-protein (GFAP) around cancer precursor lesions were studied in human and conditional murine pancreatic and colon cancer specimens using multiple immunolabeling.

RESULTS

Schwann cells migrated toward pancreatic and colon cancer cells, but not toward benign cells, before the onset of cancer migration toward peripheral neurons. This chemoattraction was inhibited after blockade of p75(NTR)-signaling on Schwann and pancreatic cancer cells. Schwann cells were specifically detected around murine and human pancreatic intraepithelial neoplasias (PanINs) (mean percent of murine PanINs surrounded by Schwann cells = 78.9%, 95% CI = 70.9 to 86.8%, and mean percent of human PanINs surrounded by Schwann cells = 52.5%, 95% CI = 14.7 to 90.4%; human: n = 44, murine: n = 14) and intestinal adenomas (mean percent of murine adenomas surrounded by Schwann cells = 64.2%, 95% CI = 28.6 to 99.8%, and mean percent of human adenomas surrounded by Schwann cells = 17.2%, 95% CI = -126.9 to 161.4; human: n = 36, murine: n = 12). The Schwann cell presence in this premalignant stage was associated with the frequency of NI in the malignant phase.

CONCLUSIONS

Schwann cells have particular and specific affinity to cancer cells. Emergence of Schwann cells in the premalignant phase of pancreatic and colon cancer implies that, in contrast with the traditional assumption, nerves-and not cancer cells-migrate first during NI.

Pancreatic stellate cells and pancreas cancer: current perspectives and future strategies

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant disease with a very poor prognosis. To date patient outcomes have not improved principally due to the limited number of patients suitable for surgical resections and the radiation and chemotherapy resistance of these tumours. In the last decade, a failure of conventional therapies has forced researchers to re-examine the environment of PDAC. The tumour environment has been demonstrated to consist of an abundance of stroma containing many cells but predominantly pancreatic stellate cells (PSCs). Recent research has focused on understanding the interaction between PSCs and PDAC cells in vitro and in vivo. It is believed that the interaction between these cells is responsible for supporting tumour growth, invasion and metastasis and creating the barrier to delivery of chemotherapeutics. Novel approaches which focus on the interactions between PDAC and PSCs which sustain the tumour microenvironment may achieve significant patient benefits. This manuscript reviews the current evidence regarding PSCs, their interaction with PDAC cells and the potential implication this may have for future therapies.

METHODS

A PubMed search was carried out for the terms 'pancreas cancer' OR 'pancreatic cancer', AND 'pancreatic stellate cells', NOT 'hepatic stellate cells'. All studies were screened and assessed for their eligibility and manuscripts exploring the relationship between PSCs and PDAC were included. The studies were subdivided into in vitro and in vivo groups.

RESULTS

One hundred and sixty-six manuscripts were identified and reduced to seventy-three in vitro and in vivo studies for review. The manuscripts showed that PDAC cells and PSCs interact with each other to enhance proliferation, reduce apoptosis and increase migration and invasion of cancer cells. The pathways through which they facilitate these actions provide potential targets for future novel therapies.

CONCLUSION

There is accumulating evidence supporting the multiple roles of PSCs in establishing the tumour microenvironment and supporting the survival of PDAC. To further validate these findings there is a need for greater use of physiologically relevant models of pancreatic cancer in vitro such as three dimensional co-cultures and the use of orthotopic and genetically engineered murine (GEM) models in vivo.

Periostin is required for maximal airways inflammation and hyperresponsiveness in mice

BACKGROUND

Periostin, a secreted extracellular matrix protein, has been localized to deposits of subepithelial fibrosis in asthmatic patients, and periostin levels have been linked to increases in IL-13.

OBJECTIVE

We hypothesized that periostin is required for airway inflammatory responses to a physiologic aeroallergen, house dust mite (HDM).

METHODS

We studied F4-F6 B6;129-Postn(tm1Jmol)/J wild-type (Postn(+/+)) and null (Postn(-/-)) mice, as well as C57BL/6 mice treated with either IgM or OC-20 periostin neutralizing antibody. Mice were exposed to 5 doses of HDM intranasally over a 16-day period.

RESULTS

HDM increased airways responsiveness in Postn(+/+) but not Postn(-/-) mice. In addition, HDM-treated C57BL/6 mice injected with OC-20 had lower airways responsiveness than HDM-treated mice injected with IgM. Compared with Postn(+/+) mice, Postn(-/-) mice showed decreases in HDM-induced inflammation and mucous metaplasia, as well as reduced IL-4, IL-25, CD68, Gob5, and periostin mRNA expression. OC-20 antibody produced similar results. HDM exposure increased periostin expression in the airway epithelium, subepithelium, smooth muscle and inflammatory cells. OC-20 blocked the HDM-induced IgE response, and T cells incubated with dendritic cells (DCs) from Postn(-/-) mice or treated with OC-20 showed deficient DNA synthesis and IL-13 responses compared with T cells incubated with wild-type DCs. Finally, adoptive transfer of bone marrow-derived DCs from Postn(+/+) mice was sufficient to promote allergic responses in F6 Postn(-/-) littermates.

CONCLUSIONS

In mice, periostin is required for maximal airways hyperresponsiveness and inflammation after HDM sensitization and challenge. Periostin is required for maximal HDM-induced T-cell responses.

Chondroitin sulfate proteoglycan CSPG4 as a novel hypoxia-sensitive marker in pancreatic tumors

CSPG4 marks pericytes, undifferentiated precursors and tumor cells. We assessed whether the shed ectodomain of CSPG4 (sCSPG4) might circulate and reflect potential changes in CSPG4 tissue expression (pCSPG4) due to desmoplastic and malignant aberrations occurring in pancreatic tumors. Serum sCSPG4 was measured using ELISA in test (n = 83) and validation (n = 221) cohorts comprising donors (n = 11+26) and patients with chronic pancreatitis (n = 11+20) or neoplasms: benign (serous cystadenoma SCA, n = 13+20), premalignant (intraductal dysplastic IPMNs, n = 9+55), and malignant (IPMN-associated invasive carcinomas, n = 4+14; ductal adenocarcinomas, n = 35+86). Pancreatic pCSPG4 expression was evaluated using qRT-PCR (n = 139), western blot analysis and immunohistochemistry. sCSPG4 was found in circulation, but its level was significantly lower in pancreatic patients than in donors. Selective maintenance was observed in advanced IPMNs and PDACs and showed a nodal association while lacking prognostic relevance. Pancreatic pCSPG4 expression was preserved or elevated, whereby neoplastic cells lacked pCSPG4 or tended to overexpress without shedding. Extreme pancreatic overexpression, membranous exposure and tissue^high/sera^low-discordance highlighted stroma-poor benign cystic neoplasm. SCA is known to display hypoxic markers and coincide with von-Hippel-Lindau and Peutz-Jeghers syndromes, in which pVHL and LBK1 mutations affect hypoxic signaling pathways. In vitro testing confined pCSPG4 overexpression to normal mesenchymal but not epithelial cells, and a third of tested carcinoma cell lines; however, only the latter showed pCSPG4-responsiveness to chronic hypoxia. siRNA-based knockdowns failed to reduce the malignant potential of either normoxic or hypoxic cells. Thus, overexpression of the newly established conditional hypoxic indicator, CSPG4, is apparently non-pathogenic in pancreatic malignancies but might mark distinct epithelial lineage and contribute to cell polarity disorders. Surficial retention on tumor cells renders CSPG4 an attractive therapeutic target. Systemic ‘drop and restoration’ alterations accompanying IPMN and PDAC progression indicate that the interference of pancreatic diseases with local and remote shedding/release of sCSPG4 into circulation deserves broad diagnostic exploration.

Pancreatic ductal adenocarcinoma: a review of immunologic aspects

With the continued failures of both early diagnosis and treatment options for pancreatic cancer, it is now time to comprehensively evaluate the role of the immune system on the development and progression of pancreatic cancer. It is important to develop strategies that harness the molecules and cells of the immune system to treat this disease. This review will focus primarily on the role of immune cells in the development and progression of pancreatic ductal adenocarcinoma and to evaluate what is known about the interaction of immune cells with the tumor microenvironment and their role in tumor growth and metastasis. We will conclude with a brief discussion of therapy for pancreatic cancer and the potential role for immunotherapy. We hypothesize that the role of the immune system in tumor development and progression is tissue specific. Our hope is that better understanding of this process will lead to better treatments for this devastating disease.

Human Pancreatic Cancer-Associated Stellate Cells Remain Activated after in vivo Chemoradiation

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extensive fibrotic reaction or desmoplasia and complex involvement of the surrounding tumor microenvironment. Pancreatic stellate cells are a key mediator of the pancreatic matrix and they promote progression and invasion of pancreatic cancer by increasing cell proliferation and offering protection against therapeutic interventions. Our study utilizes human tumor-derived pancreatic stellate cells (HTPSCs) isolated from fine needle aspirates of pancreatic cancer tissue from patients with locally advanced, unresectable pancreatic adenocarcinoma before and after treatment with full-dose gemcitabine plus concurrent hypo-fractionated stereotactic radiosurgery. We show that HTPSCs survive in vivo chemotherapy and radiotherapy treatment and display a more activated phenotype post-therapy. These data support the idea that stellate cells play an essential role in supporting and promoting pancreatic cancer and further research is needed to develop novel treatments targeting the pancreatic tumor microenvironment.

Periostin accelerates human malignant melanoma progression by modifying the melanoma microenvironment

Given no reliable therapy for advanced malignant melanoma, it is important to elucidate the molecular mechanisms underlying the disease progression. Using a quantitative proteomics approach, the 'isobaric tags for relative and absolute quantitation (iTRAQ)' method, we identified that the extracellular matrix protein, periostin (POSTN), was highly expressed in invasive melanoma compared with normal skin. An immunohistochemical analysis showed that POSTN was expressed in all invasive melanoma (n = 20) and metastatic lymph node (n = 5) tissue samples, notably restricted in their stroma. In terms of the intercellular regulation of POSTN, we found that there was upregulation of POSTN when melanoma cells and normal human dermal fibroblasts (NHDFs) were cocultured, with restricted expression of TGF-β1 and TGF-β3. In a functional analyses, recombinant and NHDF-derived POSTN significantly accelerated melanoma cell proliferation via the integrin/mitogen-activated protein kinase (MAPK) signaling pathway in vitro. The size of implanted melanoma tumors was significantly suppressed in POSTN/Rag2 double knockout mice compared with Rag2 knock-out mice. These results indicate that NHDF-derived POSTN accelerates melanoma progression and might be a promising therapeutic target for malignant melanoma.

The role of periostin in tissue remodeling across health and disease

Periostin, also termed osteoblast-specific factor 2, is a matricellular protein with known functions in osteology, tissue repair, oncology, cardiovascular and respiratory systems, and in various inflammatory settings. However, most of the research to date has been conducted in divergent and circumscribed areas meaning that the overall understanding of this intriguing molecule remains fragmented. Here, we integrate the available evidence on periostin expression, its normal role in development, and whether it plays a similar function during pathologic repair, regeneration, and disease in order to bring together the different research fields in which periostin investigations are ongoing. In spite of the seemingly disparate roles of periostin in health and disease, tissue remodeling as a response to insult/injury is emerging as a common functional denominator of this matricellular molecule. Periostin is transiently upregulated during cell fate changes, either physiologic or pathologic. Combining observations from various conditions, a common pattern of events can be suggested, including periostin localization during development, insult and injury, epithelial-mesenchymal transition, extracellular matrix restructuring, and remodeling. We propose mesenchymal remodeling as an overarching role for the matricellular protein periostin, across physiology and disease. Periostin may be seen as an important structural mediator, balancing appropriate versus inappropriate tissue adaption in response to insult/injury.

The expression and immunohistochemical localization of periostin in odontogenic tumors of mixed epithelial/mesenchymal origin

OBJECTIVE

The object of this study was to determine the expression and localization of periostin in the major mixed odontogenic tumors and to correlate any differential staining of the mesenchymal components to the interrelationship of these tumors.

STUDY DESIGN

Five ameloblastic fibromas, 8 ameloblastic fibro-odontomas and 10 odontomas were assessed immunohistochemically for periostin staining. Because mesenchymal tissues were consistently present in all studied cases, these tissues were selected for statistical analysis of differential periostin staining.

RESULTS

Periostin was variably localized to the mesenchymal component of the tumors as well as to preameloblasts and ameloblasts. Analysis of the mesenchymal staining intensity was statistically significantly different between ameloblastic fibro-odontomas and odontomas (P < .001; Dunn multiple comparisons test).

CONCLUSIONS

Our results document periostin staining in human mixed odontogenic tumors. Statistical analysis of differential stromal staining supports the concept that the ameloblastic fibroma is a histogenetically distinct neoplasm as compared to ameloblastic fibro-odontoma and odontoma.

Periostin in allergic inflammation

Periostin, an extracellular matrix protein belonging to the fasciclin family, has been shown to play a critical role in the process of remodeling during tissue/organ development or repair. Periostin functions as a matricellular protein in cell activation by binding to their receptors on cell surface, thereby exerting its biological activities. After we found that periostin is a downstream molecule of interleukin (IL)-4 and IL-13, signature cytokines of type 2 immune responses, we showed that periostin is a component of subepithelial fibrosis in bronchial asthma, the first formal proof that periostin is involved in allergic inflammation. Subsequently, a great deal of evidence has accumulated demonstrating the significance of periostin in allergic inflammation. It is of note that in skin tissues, periostin is critical for amplification and persistence of allergic inflammation by communicating between fibroblasts and keratinocytes. Furthermore, periostin has been applied to development of novel diagnostics or therapeutic agents for allergic diseases. Serum periostin can reflect local production of periostin in inflamed lesions induced by Th2-type immune responses and also can predict the efficacy of Th2 antagonists against bronchial asthma. Blocking the interaction between periostin and its receptor, αv integrin, or down-regulating the periostin expression shows improvement of periostin-induced inflammation in mouse models or in in vitro systems. It is hoped that diagnostics or therapeutic agents targeting periostin will be of practical use in the near future.

Periostin: a novel prognostic and therapeutic target for genitourinary cancer?

Many of the cellular abnormalities present in solid tumors are structural in nature and involve the proteins of the extracellular matrix (ECM). Periostin is a protein produced and secreted by the fibroblasts as a component of the ECM where it is involved in regulating intercellular adhesion. The expression of periostin has an important physiological role during embryogenesis and growth, namely at the level of bone, dental, and cardiac tissues. Many studies indicate that periostin plays an important role for tumor progression in various types of cancer, such as colon, lung, head and neck, breast, ovarian, and prostate. To the best of our knowledge, a limited number of studies have investigated periostin expression in urogenital cancer, such as prostate, bladder, penile, and renal cancer, and no studies were performed in testis cancer. In this review article, we summarize the most recent knowledge of periostin, its genetic and protein structure, and the role of the different isoforms identified and sequenced so far. In particular, we focus our attention on the role of this protein in genitourinary tumors, trying to emphasize the role not only as a possible prognostic marker, but also as a possible target for the development of future anticancer therapies.

Stars and stripes in pancreatic cancer: role of stellate cells and stroma in cancer progression

Pancreatic cancer is a devastating disease with an unacceptably high mortality to incidence ratio. Traditional therapeutic approaches such as surgery in combination with chemo- or radiotherapy have had limited efficacy in improving the outcome of this disease. Up until just under a decade ago, the prominent desmoplastic reaction which is a characteristic of the majority of pancreatic ductal adenocarcinomas (PDAC) had been largely ignored. However, since the identification of the pancreatic stellate cell (PSC) as the key cell responsible for the production of the collagenous stroma in PDAC, increasing attention has been paid to the role of the stromal reaction in pancreatic cancer pathobiology. There is now compelling evidence that PSCs interact not only with cancer cells themselves, but with several other cell types in the stroma (endothelial cells, immune cells, and possibly neuronal cells) to promote cancer progression. This review summarizes current knowledge in the field about the influence of PSCs and the stromal microenvironment on cancer behavior and discusses novel therapeutic approaches which reflect an increasing awareness amongst clinicians and researchers that targeting cancer cells alone is no longer sufficient to improve patient outcome and that combinatorial treatments targeting the stroma as well as the cancer cells will be required to change the clinical course of this disease.

Potential applications of nanotechnology for the diagnosis and treatment of pancreatic cancer

Despite improvements in our understanding of pancreatic cancer and the emerging concept of personalized medicine for the treatment of this disease, it is still the fourth most common cause of cancer death in the western world. It is established that pancreatic cancer is a highly heterogeneous disease with a complex tumor microenvironment. Indeed the extensive stroma surrounding the cancer cells has been shown to be important in promoting tumor growth and metastases, as well as sequestering chemotherapeutic agents consequently decreasing delivery to the tumor cells. Nanotechnology has come to the forefront in the areas of medical diagnostics, imaging, and therapeutic drug delivery. This review will focus on the potential applications of nanotechnology for diagnosis, imaging, and delivery of therapeutic agents for the treatment of pancreatic cancer.

Insidious changes in stromal matrix fuel cancer progression

Reciprocal interactions between tumor and stromal cells propel cancer progression and metastasis. A complete understanding of the complex contributions of the tumor stroma to cancer progression necessitates a careful examination of the extracellular matrix (ECM), which is largely synthesized and modulated by cancer-associated fibroblasts. This structurally supportive meshwork serves as a signaling scaffold for a myriad of biologic processes and responses favoring tumor progression. The ECM is a repository for growth factors and cytokines that promote tumor growth, proliferation, and metastasis through diverse interactions with soluble and insoluble ECM components. Growth factors activated by proteases are involved in the initiation of cell signaling pathways essential to invasion and survival. Various transmembrane proteins produced by the cancer stroma bind the collagen and fibronectin-rich matrix to induce proliferation, adhesion, and migration of cancer cells, as well as protease activation. Integrins are critical liaisons between tumor cells and the surrounding stroma, and with their mechano-sensing ability, induce cell signaling pathways associated with contractility and migration. Proteoglycans also bind and interact with various matrix proteins in the tumor microenvironment to promote cancer progression. Together, these components function to mediate cross-talk between tumor cells and fibroblasts ultimately to promote tumor survival and metastasis. These stromal factors, which may be expressed differentially according to cancer stage, have prognostic utility and potential. This review examines changes in the ECM of cancer-associated fibroblasts induced through carcinogenesis, and the impact of these changes on cancer progression. The implication is that cancer progression, even in epithelial cancers, may be based in large part on changes in signaling from cancer-associated stromal cells. These changes may provide early prognostic indicators to further stratify patients during treatment or alter the timing of their follow-up visits and observations.

The niche component periostin is produced by cancer-associated fibroblasts, supporting growth of gastric cancer through ERK activation

Overexpression of periostin (POSTN), an extracellular matrix protein, has been observed in several cancers. We investigated the importance of POSTN in gastric cancer. Genome-wide gene expression analysis using publicly available microarray data sets revealed significantly high POSTN expression in cancer tissues from stage II-IV gastric cancer, compared with background normal tissues. The POSTN/vimentin mRNA expression ratio was highly associated with gene groups that regulate the cell cycle and cell proliferation. IHC showed that periglandular POSTN deposition, comprising linear deposition abutting the glandular epithelial cells in normal mucosa, disappeared during intestinal gastric cancer progression. Stromal POSTN deposition was also detected at the invasive front of intestinal-type and diffuse-type cancers. In situ hybridization confirmed POSTN mRNA in cancer-associated fibroblasts, but not in tumor cells themselves. POSTN enhanced the in vitro growth of OCUM-2MLN and OCUM-12 diffuse-type gastric cancer cell lines, accompanied by the activation of ERK. Furthermore, coinoculation of gastric cancer cells with POSTN-expressing NIH3T3 mouse fibroblast cells facilitated tumor formation. The OCUM-2MLN orthotopic inoculation model demonstrated that tumors of the gastric wall in Postn(-/-) mice were significantly smaller than those in wild-type mice. Ki-67 and p-ERK positive rates were both lower in Postn(-/-) mice. These findings suggest that POSTN produced by cancer-associated fibroblasts constitutes a growth-supportive microenvironment for gastric cancer.

Novel therapeutic strategies targeting tumor-stromal interactions in pancreatic cancer

Therapy-resistance and postoperative recurrence are causes of the poor prognosis in pancreatic cancer. Conventional therapies have a limited impact on the control of pancreatic cancer, resulting in the rapid re-growth of the tumor. The indispensable role of tumor-stromal interaction, which acts as a defender of cancer cells and enhances malignant potential, is being uncovered now. For example, specific signaling pathways for desmoplasia induction have been identified, such as sonic hedgehog (Shh) or connective tissue growth factor (CTGF), whose inhibition causes desmoplasia depletion and therapeutic advantages at least in in vivo mouse models of pancreatic cancer. Revolutions in drug delivery methods have led to the establishment of novel chemotherapeutic regimens, with better patient survival. Furthermore, mechanisms of immunosuppression in the pancreatic cancer-bearing host were clarified by the identification of myeloid-derived suppressor cells (MDSCs), which also promote disease progression. Strategies to target these components of the tumor stroma revealed certain anticancer effects in vitro and in vivo, suggesting the possibility of stroma-targeting therapy. Suppression of the stromal cell function increases the sensitivity of pancreatic cancer cells to therapeutic intervention. Further study will clarify the complex nature of the tumor microenvironment, the targeting of which has the potential to improve clinical outcome.

The stromal compartments in pancreatic cancer: are there any therapeutic targets?

Pancreatic ductal adenocarcinoma (PDAC) is characterised by an abundant stromal response also known as a desmoplastic reaction. Pancreatic Stellate Cells have been identified as playing a key role in pancreatic cancer desmoplasia. There is accumulating evidence that the stroma contributes to tumour progression and to the low therapeutic response of PDAC patients. In this review we described the main actors of the desmoplastic reaction within PDAC and novel therapeutic approaches that are being tested to block the detrimental function of the stroma.

A bioengineered heterotypic stroma-cancer microenvironment model to study pancreatic ductal adenocarcinoma

Interactions between neoplastic epithelial cells and components of a reactive stroma in pancreatic ductal adenocarcinoma (PDAC) are of key significance behind the disease's dismal prognosis. Despite extensive published research in the importance of stroma-cancer interactions in other cancers and experimental evidence supporting the importance of the microenvironment in PDAC progression, a reproducible three-dimensional (3D) in vitro model for exploring stroma-cancer interplay and evaluating therapeutics in a physiologically relevant context has been lacking. We introduce a humanized microfluidic model of the PDAC microenvironment incorporating multicellularity, extracellular matrix (ECM) components, and a spatially defined 3D microarchitecture. Pancreatic stellate cells (PSCs) isolated from clinically-evaluated human tissue specimens were co-cultured with pancreatic ductal adenocarcinoma cells as an accessible 3D construct that maintained important tissue features and disease behavior. Multiphoton excitation (MPE) and Second Harmonic Generation (SHG) imaging techniques were utilized to image the intrinsic signal of stromal collagen in human pancreatic tissues and live cell-collagen interactions within the optically-accessible microfluidic tissue model. We further evaluated the dose-response of the model with the anticancer agent paclitaxel. This bioengineered model of the PDAC stroma-cancer microenvironment provides a complementary platform to elucidate the complex stroma-cancer interrelationship and to evaluate the efficacy of potential therapeutics in a humanized system that closely recapitulates key PDAC microenvironment characteristics.

Hypoxia pathways and cellular stress activate pancreatic stellate cells: development of an organotypic culture model of thick slices of normal human pancreas

Pancreatic stellate cells (PSC) are involved in fibrogenesis and oncogenesis by modulating the extracellular matrix.

Activation of alpha-smooth muscle actin-positive myofibroblast-like cells after chemotherapy with gemcitabine in a rat orthotopic pancreatic cancer model

BACKGROUND

To investigate the behavior of activated pancreatic stellate cells (PSCs), which express alpha-smooth muscle actin (α-SMA), and pancreatic cancer cells in vivo, we examined the expression of α-SMA-positive myofibroblast-like cells in pancreatic cancer tissue after treatment with gemcitabine (GEM) using a Lewis orthotopic rat pancreatic cancer model.

METHODS

The effect of GEM on DSL-6A/C1 cell proliferation was determined by cell counting method. The orthotopic pancreatic cancer animals were prepared with DSL-6A/C cells, and treated with GEM (100 mg/kg/weekly, for 3 weeks). At the end of treatment, α-SMA expression, fibrosis, transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF) were evaluated by histopathological and Western blot analyses.

RESULTS

DSL-6A/C1 cell proliferation was significantly reduced by co-culturing with GEM in vitro. Survival time of pancreatic cancer animals (59.6 ± 13.4 days) was significantly improved by treatment with GEM (89.6 ± 21.8 days; p = 0.0005). Alpha-SMA expression in pancreatic cancer tissue was significantly reduced after treatment with GEM (p = 0.03), however, there was no significant difference in Sirius-red expression. Expression of VEGF was significantly reduced by GEM treatment, but the expression of TGF-β1 was not inhibited.

CONCLUSION

GEM may suppress not only the tumor cell proliferation but also suppress PSCs activation through VEGF reduction.

Targeting TGFβ signaling to inhibit fibroblast activation as a therapy for fibrosis and cancer: effect of halofuginone

The fibroblast to myofibroblast transition in wound healing, fibrosis and cancer has emerged as a viable target for pharmacological intervention. The myofibroblasts acquire specific characteristics because of differences in origin and localization, but also share common properties, such as TGFβ signaling. Halofuginone, an inhibitor of the Smad3 phosphorylation, downstream of the TGFβ signaling, inhibits the activation of fibroblasts and their ability to synthesize the extracellular matrix, regardless of their origin or location. Halofuginone prevented the new and stimulated resolution of pre-existing fibrosis of several organs and inhibited the development and progression of various tumors. Moreover, halofuginone synergizes with chemotherapy and reduces the need for high doses of toxic compounds without impairing the treatment efficacy. In fibrosis, where the myofibroblasts are the major participant, halofuginone can be used as a single therapy, whereas in cancer it should be considered in combination with other therapies that affect the tumor cells via different modalities.

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.

The role of pancreatic stellate cells in pancreatic cancer

Since conventional and targeted therapies aiming at cancer cells have largely failed to prolong survival in pancreatic cancer, targeting the infrastructure of the tumor, hence its stroma is a novel strategy. It is believed that fibrotic and hypovascular stroma forms a barrier around cancer cells, hindering effective delivery of chemotherapy. Theoretically, antifibrotic therapy should reduce the compactness of the stroma and reduce the interstitial pressure, allowing better delivery of chemotherapy. This approach has worked successfully in a genetically engineered mouse model but failed in humans, paradoxically increasing mortality in the treatment arm. Normally, stromal cells deposit extracellular matrix as an innate defensive reaction to form a barrier between what is harmful and the rest of the body. Despite the significant amount of in vitro data suggesting the pro-tumorigenic roles of activated stellate cells, there is no reason to believe that stellate cells around genetically mutated cells are from the beginning there to support carcinogenesis. Such a stromal activation is also observed around PanIN lesions (which harbor genetically mutated cells) in chronic pancreatitis, where no cancer develops. In pancreatic cancer, the selection pressure created by the fibrotic and hypoxic stroma eventually leads to the evolution of more aggressive clones, indirectly contributing to the aggressiveness of the tumor. Here, the main problem is the late diagnosis of pancreatic cancer, which gives cancer cells enough time for malignant evolution. Therefore, applying antifibrotic therapy at a late stage can be counterproductive. It may increase delivery of chemotherapy, but also lead to the escape of cancer cells.