Osteopontin expression is associated with improved survival in patients with pancreatic adenocarcinoma

CRISPR/Cas9 mediated knocking out of OPN gene enhances radiosensitivity in MDA-MB-231 breast cancer cell line

PURPOSE

Although chemotherapy and radiotherapy in conjunction with surgery have been known as the standard methods for patients with breast cancer, they frequently face resistance due to the failure of cells to death. Accordingly, improving the results requires discovering novel therapeutic approaches based on the changes in the molecular biology of cancer cells. Osteopontin (OPN) is a secreted protein that previous studies have shown to be associated with progression, poor prognosis, and metastasis in breast cancer. The current study examined the synergistic effects of radiotherapy and knocking out of OPN gene, utilizing CRISPR/Cas9 technique in MDA-MB-231 breast cancer cells.

METHODS

We used to knock out the OPN gene by the two different gRNAs. The cells irradiated 24 h after transfection. The mRNA expression, tumor cell proliferation, cell cycle distribution, growth, and apoptosis were measured. Moreover, activation of Chk1 and AKT were measured via western blot.

RESULTS

We demonstrated the OPN knocking out along with radiation led to the promotion of apoptosis, suppression of downstream genes, reduction of cell viability, and inhibition of cell-cycle progression. The western blot analysis has indicated that the knocking out of the OPN gene along with radiotherapy changes DNA damage responses substantially.

CONCLUSIONS

The OPN gene knocking out with radiotherapy might be an efficient approach to overcome the radioresistance in breast cancer.

The Role of Adipokines in Pancreatic Cancer

In modern society, inappropriate diets and other lifestyle habits have made obesity an increasingly prominent health problem. Pancreatic cancer (PC), a kind of highly aggressive malignant tumor, is known as a silent assassin and is the seventh leading cause of cancer death worldwide, pushing modern medicine beyond help. Adipokines are coming into notice because of the role of the intermediate regulatory junctions between obesity and malignancy. This review summarizes the current evidence for the relationship between highly concerning adipokines and the pathogenesis of PC. Not only are classical adipokines such as leptin and adiponectin included, but they also cover the recognized chemerin and osteopontin. Through a summary of the biological functions of these adipokines as well as their receptors, it was discovered that in addition to their basic function of stimulating the biological activity of tumors, more studies confirm that adipokines intervene in the progression of PC from the viewpoint of tumor metabolism, immune escape, and reprogramming of the tumor microenvironment (TME). Besides endocrine function, the impact of white adipose tissue (WAT)-induced chronic inflammation on PC is briefly discussed. Furthermore, the potential implication of the acknowledged endocrine behavior of brown adipose tissue (BAT) in relation to carcinogenesis is also explored. No matter the broad spectrum of obesity and the poor prognosis of PC, supplemental research is needed to unravel the detailed network of adipokines associated with PC. Exploiting profound therapeutic strategies that target adipokines and their receptors may go some way to improving the current worrying prognosis of PC patients.

A Noncanonical Hedgehog Signaling Exerts a Tumor-Promoting Effect on Pancreatic Cancer Cells Via Induction of Osteopontin Expression

Objective: Sonic Hedgehog (Shh)-Gli1 signaling and osteopontin (OPN) play vital roles in pancreatic cancer. However, the precise mechanisms of both signals have not been fully clarified, and whether there is a correlation between them in pancreatic ductal adenocarcinoma (PDAC) is unknown. This study aims to confirm the effect of OPN on human PDAC and assess whether Hh signaling affects pancreatic cancer cells through upregulation of OPN. Materials and Methods: OPN expression in human PDAC tissues and cell lines was investigated. Proliferation, apoptosis, migration, and invasion of OPN-knockdown BxPC-3 cells were observed. We analyzed the correlation between Shh or Gli1 and OPN expression in human PDAC. Hh signaling inhibitors and shRNA against Gli1 were used to confirm if OPN expression in BxPC-3 cells was regulated by Hh canonical or noncanonical pathway. We also evaluated the proliferation, apoptosis, migration, and invasion of Gli1-knockdown BxPC-3 cells. Results: OPN is highly expressed in human PDAC tissues and cell lines. The proliferation, migration, and invasion of BxPC-3 cell lines were decreased, whereas apoptosis was increased when OPN was knocked down. Correlation analysis showed that Gli1, but not Shh, was associated with OPN expression in human PDAC, and Gli1 regulated OPN production in BxPC-3 cells through a noncanonical pathway because Gli but not Smo inhibitor reduced OPN expression. Similar to above, the proliferation, migration, and invasion of BxPC-3 cells were decreased, whereas the apoptosis was increased when Gli1 was knocked down. Supplement of exogenous OPN protein could partially reverse the effect of both OPN knockdown and Gli1 knockdown on the bio-behavior of BxPC-3 cells. Conclusion: Hh signaling promotes proliferation, migration, and invasion but inhibits apoptosis of pancreatic cancer cells through upregulation of OPN in a noncanonical pathway.

Breast cancer radioresistance may be overcome by osteopontin gene knocking out with CRISPR/Cas9 technique

PURPOSE

Osteopontin (OPN) is a phosphoglycoprotein, with a wide range of physiological and pathological roles. High expression of OPN promotes aggressive behavior, causes poor prognosis in tumor cells, and reduces the survival of patients. Since overexpression of OPN gives rise to radioresistance, the effects of the gene knock out using the CRISPR/Cas9 system in combination with radiation are emphasized.

MATERIAL AND METHODS

We used the CRISPR/Cas9 technique to knock out the OPN gene in the MDA-MB-231 cell line. After transfection, the cells were irradiated. The changes of the OPN mRNA levels, the apoptosis, and the differences in cell viability were assessed.

RESULTS

A significant reduction in the OPN expression was observed alone or along with irradiation. The knocked out gene alone increased apoptosis rate. The cell viability decreased to after knocking out of the OPN gene. The gene knocking-out combined with irradiation led to more decline of cell viability.

CONCLUSION

Our results demonstrated that after knocking out the OPN gene, the MDA-MB-231 cells showed a significant radiosensitivity. Therefore, the OPN knock out in combination with conventional radiotherapy, may become an efficient therapeutic target in the future.

Osteopontin expression is associated with progression and adverse prognosis in patients with resectable gastrointestinal stromal tumor

OBJECTIVES

Osteopontin (OPN) is reported to be particularly associated with the progression of several human malignancies. This study was designed to examine the clinicopathologic significance of OPN in gastrointestinal stromal tumor (GISTs).

METHODS

The level of OPN expression in a large cohort of resectable GISTs was evaluated with immunohistochemistry. Its correlation with the clinicopathologic parameters of patients with resectable GISTs was analyzed. A survival analysis was performed to evaluate the prognostic significance of OPN expression using the Kaplan-Meier method.

RESULTS

In 108 patients with resectable GISTs, the most high-risk GISTs had a strong level of OPN expression. Strong OPN expression was also significantly associated with tumor size, mitosis, and recurrence, but not gender and age. Patients with weak OPN expression had a relatively longer disease-free survival compared to patients with strong OPN expression.

CONCLUSIONS

OPN expression is a putative marker for tumor progression and an adverse prognosis in GISTs.

Novel prognostic markers within the CD44-stromal ligand network in pancreatic cancer

The dense stroma in pancreatic cancer tumours is rich in secreted extracellular matrix proteins and proteoglycans. Secreted hyaluronan, osteopontin and type IV collagen sustain oncogenic signalling by interactions with CD44s and its variant isoform CD44v6 on cancer cell membranes. Although well established in animal and in vitro models, this oncogenic CD44-stromal ligand network is less explored in human cancer. Here, we use a pancreatic cancer tissue microarray from 69 primary tumours and 37 metastatic lymph nodes and demonstrate that high tumour cell expression of CD44s and, surprisingly, low stromal deposition of osteopontin correlate with poor survival independent of established prognostic factors for pancreatic cancer. High stromal expression of hyaluronan was a universal trait of both primary tumours and metastatic lymph nodes. However, hyaluronan species of different molecular mass are known to function differently in pancreatic cancer biology and immunohistochemistry cannot distinguish between them. Using gas-phase electrophoretic molecular mobility analysis, we uncover a shift towards high molecular mass hyaluronan in pancreatic cancer tissue compared to normal pancreas and at a transcriptional level, we find that hyaluronan synthesising HAS2 correlates positively with CD44. The resulting prediction that high molecular mass hyaluronan would then correlate with poor survival in pancreatic cancer was confirmed in serum samples, where we demonstrate that hyaluronan >27 kDa measured before surgery is an independent predictor of postoperative survival. Our findings confirm the prognostic value of CD44 tissue expression and highlight osteopontin tissue expression and serum high molecular mass hyaluronan as novel prognostic markers in pancreatic cancer.

Osteopontin b and c Splice isoforms in Leukemias and Solid Tumors: Angiogenesis Alongside Chemoresistance

Osteopontin (OPN) is a glycoprotein involved in regulation of various influences on tumor progression, such as cellular proliferation, apoptosis, angiogenesis, and metastasis. Vascular endothelial growth factor (VEGF) is a secreted molecule supporting angiogenesis in various cancers through activation of the PI3K/AKT/ERK1/2 pathway. OPN and VEGF have a number of isoforms with various activities. In spite of the well-defined association between OPN and VEGF isoform expression and cure rate for solid tumors, there is a scarcity of information as to any association in leukemia. Based on the critical role of OPN in cell survival, it seems reasonable to hypothesize that OPN and VEGF isoform expression levels may impact on chemoresistance and relapse in leukemia the same as in solid tumors. Hence, the aim of our review was to explain relationships between OPN and VEGF isoforms and angiogenesis and related pathways in chemoresistance of leukemia and solid tumors. Our findings demonstrated that OPNb and OPNc alongside with VEGF isoforms and other gene pathways are involved in angiogenesis and also might promote chemoresistance and even recurrence in leukemia and solid tumors. To sum up, targeting OPN isoforms, particularly b and c, might be a novel therapeutic strategy for the treatment of leukemia as well as solid tumors.

Matricellular proteins and survival in patients with pancreatic cancer: A systematic review

Extracellular matrix (ECM) plays a fundamental role in tissue architecture and homeostasis and modulates cell functions through a complex interaction between cell surface receptors, hormones, several bioeffector molecules, and structural proteins like collagen. These components are secreted into ECM and all together contribute to regulate several cellular activities including differentiation, apoptosis, proliferation, and migration. The so-called "matricellular" proteins (MPs) have recently emerged as important regulators of ECM functions. The aim of our review is to consider all different types of MPs family assessing the potential relationship between MPs and survival in patients with pancreatic ductal adenocarcinoma (PDAC). A systematic computer-based search of published articles, according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) Statement issued in 2009 was conducted through Ovid interface, and literature review was performed in May 2017. The search text words were identified by means of controlled vocabulary, such as the National Library of Medicine's MESH (Medical Subject Headings) and Keywords. Collected data showed an important role of MPs in carcinogenesis and in PDAC prognosis even though the underlying mechanisms are still largely unknown and data are not univocal. Therefore, a better understanding of MPs role in regulation of ECM homeostasis and remodeling of specific organ niches may suggest potential novel extracellular targets for the development of efficacious therapeutic strategies.

Is Osteopontin a Friend or Foe of Cell Apoptosis in Inflammatory Gastrointestinal and Liver Diseases?

Osteopontin (OPN) is involved in a variety of biological processes, including bone remodeling, innate immunity, acute and chronic inflammation, and cancer. The expression of OPN occurs in various tissues and cells, including intestinal epithelial cells and immune cells such as macrophages, dendritic cells, and T lymphocytes. OPN plays an important role in the efficient development of T helper 1 immune responses and cell survival by inhibiting apoptosis. The association of OPN with apoptosis has been investigated. In this review, we described the role of OPN in inflammatory gastrointestinal and liver diseases, focusing on the association of OPN with apoptosis. OPN changes its association with apoptosis depending on the type of disease and the phase of disease activity, acting as a promoter or a suppressor of inflammation and inflammatory carcinogenesis. It is essential that the roles of OPN in those diseases are elucidated, and treatments based on its mechanism are developed.

Human osteopontin: Potential clinical applications in cancer (Review)

Human osteopontin (OPN) is a glycosylated phosphoprotein which is expressed in a variety of tissues in the body. In recent years, accumulating evidence has indicated that the aberrant expression of OPN is closely associated with tumourigensis, progression and most prominently with metastasis in several tumour types. In this review, we present the current knowledge on the expression profiles of OPN and its main splice variants in human cancers, as well as the potential implications in patient outcome. We also discuss its putative clinical application as a cancer biomarker and as a therapeutic target.

Gene expression profiling in bladder cancer identifies potential therapeutic targets

Despite advances in management, bladder cancer remains a major cause of cancer related complications. Characterisation of gene expression patterns in bladder cancer allows the identification of pathways involved in its pathogenesis, and may stimulate the development of novel therapies targeting these pathways. Between 2004 and 2005, cystoscopic bladder biopsies were obtained from 19 patients and 11 controls. These were subjected to whole transcript-based microarray analysis. Unsupervised hierarchical clustering was used to identify samples with similar expression profiles. Hypergeometric analysis was used to identify canonical pathways and curated networks having statistically significant enrichment of differentially expressed genes. Osteopontin (OPN) expression was validated by immunohistochemistry. Hierarchical clustering defined signatures, which differentiated between cancer and healthy tissue, muscle-invasive or non-muscle invasive cancer and healthy tissue, grade 1 and grade 3. Pathways associated with cell cycle and proliferation were markedly upregulated in muscle-invasive and grade 3 cancers. Genes associated with the classical complement pathway were downregulated in non-muscle invasive cancer. Osteopontin was markedly overexpressed in invasive cancer compared to healthy tissue. The present study contributes to a growing body of work on gene expression signatures in bladder cancer. The data support an important role for osteopontin in bladder cancer, and identify several pathways worthy of further investigation.

Osteopontin as a discriminating marker for pancreatic cancer and chronic pancreatitis

INTRODUCTION

We analyzed concentrations of osteopontin (OPN) in patients with pancreatic ductal adenocarcinoma (PDAC) in order to determine firstly whether it is useful to distinguish between PDAC patients and those with chronic non-hereditary pancreatitis (CP) and type 2 diabetes mellitus (T2DM), and secondly whether OPN concentrations depend on the PDAC stage.

METHODS

Groups consisting of 64 patients with PDAC, 71 with CP, 67 with T2DM and 48 healthy controls (CON) were enrolled in the study. Controls were compared with regard to levels of OPN, oxidative stress markers, conventional tumor markers and other biochemical parameters.

RESULTS

Levels of OPN were higher in patients with PDAC compared with CP patients (P< 0.001), T2DM (P< 0.001) and CON (P< 0.001). There were increased OPN levels in CP patients in comparison with T2DM (P< 0.001) and CON (P< 0.001). Patients with PDAC in stage IV had higher OPN levels than PDAC patients in stage III (P< 0.01). There was no difference in OPN levels of PDAC patients in stage III compared to patients in stage II.

CONCLUSION

Our pilot study demonstrates the usefulness of estimating OPN levels to differentiate between pancreatic cancer and chronic pancreatitis. Higher OPN levels over 102 ng/ml could be a potential diagnostic biomarker for pancreatic cancer.

Osteopontin expression is correlated with differentiation and good prognosis in medullary thyroid carcinoma

BACKGROUND

Osteopontin (OPN) or secreted phosphoprotein 1 (SPP1) is a matricellular glycoprotein whose expression is elevated in various types of cancer and has been shown to be involved in tumourigenesis and metastasis in many malignancies, including follicular cell-derived thyroid carcinomas. Its role in C-cell-derived thyroid lesions and tumours remains to be established.

OBJECTIVE

The objective of this study is to clarify the role of OPN expression in the development of medullary thyroid carcinoma (MTC).

METHODS

OPN expression was analysed in a series of 116 MTCs by immunohistochemistry and by qPCR mRNA quantification of the 3 OPN isoforms (OPNa, OPNb and OPNc) in six cases from which fresh frozen tissue was available. Statistical tests were used to evaluate the relationship of OPN expression and the clinicopathological and molecular characteristics of patients and tumours.

RESULTS

OPN expression was detected in 91 of 116 (78.4%) of the MTC. We also observed high OPN expression in C-cell hyperplasia as well as in C-cells scattered in the thyroid parenchyma adjacent to the tumours. OPN expression was significantly associated with smaller tumour size, PTEN nuclear expression and RAS status, and suggestively associated with non-invasive tumours. OPNa isoform was expressed significantly at higher levels in tumours than in non-tumour samples. OPNb and OPNc presented similar levels of expression in all samples. Furthermore, OPNa isoform overexpression was significantly associated with reduced growth and viability in the MTC-derived cell line (TT).

CONCLUSION

The expression of OPN in normal C-cells and C-cell hyperplasia suggests that OPN is a differentiation marker of C-cells, rather than a marker of biological aggressiveness in this setting. At variance with other cancers, OPN expression is associated with good prognostic features in MTC.

SIBLINGs and SPARC families: Their emerging roles in pancreatic cancer

Pancreatic cancer has a considerably poor prognosis with a 5-year survival probability of less than 5% when all stages are combined. Pancreatic cancer is characterized by its dense stroma, which is involved in the critical interplay with the tumor cells throughout tumor progression and furthermore, creates a barrier restricting efficient penetration of therapeutics. Alterations in a large number of genes are reflected by a limited number of signaling pathways, which are potential targets. Understanding more about the molecular basis of this devastating cancer type regarding tumor microenvironment, distinct subpopulations of cells, epithelial-to-mesenchymal transition and inflammation will lead to the development of various targeted therapies for controlling tumor growth and metastasis. In this complex scenario of pancreatic cancer, especially members of the “small integrin binding ligand N-linked glycoproteins” (SIBLINGs) and “secreted protein acidic and rich in cysteine” (SPARC) families have emerged due to their prominent roles in properties including proliferation, differentiation, apoptosis, adhesion, migration, angiogenesis, wound repair and regulation of extracellular matrix remodeling. SIBLINGs consist of five members, which include osteopontin (OPN), bone sialoprotein, dentin matrix protein 1, dentin sialophosphoprotein and matrix extracellular phosphoglycoprotein. The SPARC family of modular extracellular proteins is comprised of SPARC/osteonectin (ON) and SPARC-like 1 (hevin); secreted modular calcium binding proteins; testicans and follistatin-like protein. In this review, we especially focus on OPN and ON, elaborating on their special and growing importance in pancreatic cancer diagnosis and prognosis.

Role of osteopontin in the pathophysiology of cancer

Osteopontin (OPN) is a multifunctional cytokine that impacts cell proliferation, survival, drug resistance, invasion, and stem like behavior. Due to its critical involvement in regulating cellular functions, its aberrant expression and/or splicing is functionally responsible for undesirable alterations in disease pathologies, specifically cancer. It is implicated in promoting invasive and metastatic progression of many carcinomas. Due to its autocrine and paracrine activities OPN has been shown to be a crucial mediator of cellular cross talk and an influential factor in the tumor microenvironment. OPN has been implicated as a prognostic and diagnostic marker for several cancer types. It has also been explored as a possible target for treatment. In this article we hope to provide a broad perspective on the importance of OPN in the pathophysiology of cancer.

Expression and purification of bioactive high-purity recombinant mouse SPP1 in Escherichia coli

Secreted phosphoprotein 1 (SPP1) is a phosphorylated acidic glycoprotein. It is broadly expressed in a variety of tissues, and it is involved in a number of physiological and pathological events, including cancer metastasis, tissues remodeling, pro-inflammation regulation, and cell survival. SPP1 has shown its function of protecting tissues and organs against injury and wound, giving itself potentials to become a therapy target or giving its antibodies of other counter-acting reagents potentials to become drug candidates. Non-tagged (native) recombinant SPP1 would be valuable in therapeutic and pharmaceutical researches. In our study, mouse Spp1 DNA fragment without signal peptide was built in pET28a(+) vector and transformed into Escherichia coli BL21 (DE3). The recombinant mouse SPP1 (rmSPP1) was then expressed in bacteria upon induction by isopropyl β-D-thiogalactopyranoside (IPTG). The abundance of rmSPP1 was increased using isoelectric precipitation and ammonium sulfate fractionation methods, and anion and cation exchange chromatography was employed to further purify rmSPP1. Finally, we got rmSPP1 product with 12.8 % productivity, 97 % purity, satisfactory bioactivity, and low endotoxin content.

OPN and αvβ3 expression are predictors of disease severity and worse prognosis in hepatocellular carcinoma

Expressions of OPN and αvβ3 are associated with a poor prognosis in many malignancies. However, their relationship in hepatocellular carcinoma remains unclear. We systematically collected hepatocellular carcinoma tissue samples from 305 patients over 3 years, and analyzed the status of OPN and αvβ3 in hepatocellular carcinoma and correlate expression with patient disease status and survival outcome. Our study results indicated that OPN and αvβ3 are expressed at significantly higher rates in hepatocellular carcinoma compared with adjacent non-tumorous tissue (69.5% vs 18.4%, p<0.01 and 77.4% vs 21.6%, p<0.01, respectively). Both OPN and αvβ3 expression levels are associated with poor prognostic factors, including tumor size, capsular invasion, tumor thrombus of the portal vein, metastasis of the lymph node and clinical staging. Patients expressing OPN and αvβ3 had significantly shorter survival compared with patients negative for protein expression (p<0.01). Multivariate analysis also showed that both OPN and αvβ3 expression are independent prognostic factors for poorer survival in hepatocellular carcinoma. By this study, we conclude that OPN and αvβ3 are negative prognostic predictors in patients with hepatocellular carcinoma. The expressions of both OPN and αvβ3 are associated with worse survival outcome.

Biomarkers for pancreatic cancer: promising new markers and options beyond CA 19-9

Pancreatic adenocarcinoma accounts for nearly 90-95% of exocrine malignant tumors of the pancreas. Traditionally, overexpressed proteins/epitopes such as CA 19-9, CA-50, CEA, and many others were being used as pancreatic cancer tumor markers. The main utility of these biomarkers was in the diagnosis of pancreatic cancer as well as to assess response to chemotherapy and to determine prognosis and to predict tumor recurrence. However, these markers had significant limitations such as lack of sensitivity, false-negative results in certain blood groups, as well as false-positive elevation in the presence of obstructive jaundice. To circumvent these limitations, an extraordinary amount of research is being performed to identify an accurate tumor marker or a panel of markers that could aid in the management of the pancreatic cancer. Although this research has identified a large number and different variety of biomarkers, few hold future promise as a preferred marker for pancreatic cancer. This review provides an insight into exciting new areas of pancreatic biomarker research such as salivary, pancreatic juice, and stool markers that can be used as a noninvasive test to identify pancreatic cancer. This manuscript also provides a discussion on newer biomarkers, the role of microRNAs, and pancreatic cancer proteomics, which have the potential to identify a preferred tumor marker for pancreatic adenocarcinoma. This review further elaborates on important genetic changes associated with the development and progression of pancreatic cancer that holds the key for the identification of a sensitive biomarker and which could also serve as a therapeutic target.

Biomarkers for predicting future metastasis of human gastrointestinal tumors

The recent advances in surgery and radiation therapy have significantly improved the prognosis of patients with primary cancer, and the major challenge of cancer treatment now is metastatic disease development. The 5-year survival rate of cancer patients who have distant metastasis at diagnosis is extremely low, suggesting that prediction and early detection of metastasis would definitely improve their prognosis because suitable patient therapeutic management and treatment strategy can be provided. Cancer cells from a primary site give rise to a metastatic tumor via a number of steps which require the involvement and altered expression of many regulators. These regulators may serve as biomarkers for predicting metastasis. Over the past few years, numerous regulators have been found correlating with metastasis. In this review, we summarize the findings of a number of potential biomarkers that are involved in cadherin-catenin interaction, integrin signaling, PI3K/Akt/mTOR signaling and cancer stem cell identification in gastrointestinal cancers. We will also discuss how certain biomarkers are associated with the tumor microenvironment that favors cancer metastasis.

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

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

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.