Chemokines: new, key players in the pathobiology of pancreatic cancer

Plasma CXCL3 Levels Are Associated with Tumor Progression and an Unfavorable Colorectal Cancer Prognosis

Background

The CXC chemokines belong to a unique family of chemotactic cytokines that influence the initiation, progression, and clinical outcome of many tumor types. Herein, we investigated the association of the CXC-chemokine ligand 3 (CXCL3) with tumor progression and an unfavorable prognosis for colorectal cancer (CRC).

Methods

The quantitative real-time polymerase chain reaction was used to explore the expression of CXCL3 in CRC tissue, adjacent tissue, and plasma. The usefulness of plasma levels of CXCL3 for the diagnosis of CRC was evaluated by receiver operating characteristic curve analysis. Pearson's correlation analysis assessed relationships among plasma CXCL3, cancer tissue CXCL3, and plasma carcinoembryonic antigen (CEA). Kaplan–Meier analysis was used to assess the survival of CRC patients with high and low expression levels of CXCL3. Survival differences were compared by log-rank test.

Results

Initial analysis of the GSE156720 dataset identified CXCL3 as the most enriched CXCL gene in CRC patients. Higher CXCL3 levels were detected in CRC tissue than in adjacent tissue (P < 0.001). Compared to healthy controls, CRC patient plasma CXCL3 levels were higher (P < 0.001). The area under the curve was 0.81 with a sensitivity of 0.71 and specificity of 0.82, distinguishing CRC from other tumor types. Plasma CXCL3 was positively related to CXCL3 in cancer tissue (r = 0.78, P < 0.01), and also to plasma CEA (r = 0.50, P < 0.01). Plasma CXCL3 was also related to tumor size (P = 0.034), staging (P < 0.001), tumor stage (P = 0.003), differentiation (P = 0.001), and lymph node metastasis (P = 0.007), but not to sex (P = 0.853), age (P = 0.691), tumor site (P = 1.347), or distant metastasis (P = 1.218).

Conclusions

CXCL3 levels were increased in CRC patients, with plasma CXCL3 levels associated with tumor progression and an unfavorable CRC prognosis. The results of this study suggest that plasma CXCL3 may be a novel diagnostic and prognostic biomarker for CRC.

Nerves and Pancreatic Cancer: New Insights into a Dangerous Relationship

Perineural invasion (PNI) is defined as the presence of neoplastic cells along nerves and/or within the different layers of nervous fibers: epineural, perineural and endoneural spaces. In pancreatic cancer-particularly in pancreatic ductal adenocarcinoma (PDAC)-PNI has a prevalence between 70 and 100%, surpassing any other solid tumor. PNI has been detected in the early stages of pancreatic cancer and has been associated with pain, increased tumor recurrence and diminished overall survival. Such an early, invasive and recurrent phenomenon is probably crucial for tumor growth and metastasis. PNI is a still not a uniformly characterized event; usually it is described only dichotomously ("present" or "absent"). Recently, a more detailed scoring system for PNI has been proposed, though not specific for pancreatic cancer. Previous studies have implicated several molecules and pathways in PNI, among which are secreted neurotrophins, chemokines and inflammatory cells. However, the mechanisms underlying PNI are poorly understood and several aspects are actively being investigated. In this review, we will discuss the main molecules and signaling pathways implicated in PNI and their roles in the PDAC.

Human CD26high T cells elicit tumor immunity against multiple malignancies via enhanced migration and persistence

CD8+ T lymphocytes mediate potent immune responses against tumor, but the role of human CD4+ T cell subsets in cancer immunotherapy remains ill-defined. Herein, we exhibit that CD26 identifies three T helper subsets with distinct immunological properties in both healthy individuals and cancer patients. Although CD26neg T cells possess a regulatory phenotype, CD26int T cells are mainly naive and CD26high T cells appear terminally differentiated and exhausted. Paradoxically, CD26high T cells persist in and regress multiple solid tumors following adoptive cell transfer. Further analysis revealed that CD26high cells have a rich chemokine receptor profile (including CCR2 and CCR5), profound cytotoxicity (Granzyme B and CD107A), resistance to apoptosis (c-KIT and Bcl2), and enhanced stemness (β-catenin and Lef1). These properties license CD26high T cells with a natural capacity to traffic to, regress and survive in solid tumors. Collectively, these findings identify CD4+ T cell subsets with properties critical for improving cancer immunotherapy.

IL-17RB enhances thyroid cancer cell invasion and metastasis via ERK1/2 pathway-mediated MMP-9 expression

IL-17RB, a member of the IL-17 receptor family that can be activated by IL-17B, has been proved to be involved in inflammatory diseases and cancers. However, the function of IL-17RB in thyroid cancer is still unknown. In this study, IL-17RB expression in thyroid cancer cell lines and tissues was examined by real-time PCR and western blot. The effects of IL-17RB on cell invasion and migration were determined by in vitro invasion and migration assays, while the effects of IL-17RB on cell metastasis were analyzed by in vivo experiments. The results showed that IL-17RB expression was upregulated in both thyroid cancer cells and tissues. IL-17B dose-dependently promoted the invasion, growth and migration of thyroid cancer cells, whereas knockdown of IL-17RB attenuated the effects of IL-17B in vitro. Moreover, IL-17RB was involved in the metastasis and growth of thyroid cancer cells in vivo. In addition, IL-17RB induced ERK1/2 activation and increased MMP-9 expression in vitro and in vivo. Inhibition of ERK1/2 pathway blocked the IL-17RB-mediated thyroid cancer cell invasion and MMP-9 expression. Together, our findings demonstrate that IL-17RB can enhance thyroid cancer cell invasion and metastasis via ERK1/2 pathway-mediated MMP-9 expression, suggesting that IL-17RB may act as a potential therapeutic target for thyroid cancer therapy.

Perineural invasion and associated pain in pancreatic cancer

Perineural invasion (PNI) is a prominent characteristic of pancreatic cancer. PNI is a process whereby cancer cells invade the surrounding nerves, thus providing an alternative route for metastatic spread and pain generation. PNI is thought to be an indicator of aggressive tumour behaviour and has been shown to correlate with poor prognosis of patients with pancreatic cancer. Recent studies demonstrated that some signalling molecules and pathways that are involved in PNI are also involved in pain generation. Targeting these signalling pathways has shown some promise in alleviating pain and reducing PNI, which could potentially improve treatment outcomes for patients with pancreatic cancer.

Enhanced expression and clinical significance of chemokine receptor CXCR2 in hepatocellular carcinoma

BACKGROUND

An ELR+ CXC chemokine receptor, CXCR2, was recently reported to be involved in tumorigenesis and development. However, the role of CXCR2 in hepatocellular carcinoma (HCC) is poorly understood. In this study, we aimed to investigate the association between CXCR2 expression and the biocharacteristics of HCC, and determine whether the expression of CXCR2 was related to the tumorigenesis and progression.

METHODS

Forty-two patients who underwent hepatic resection and were diagnosed as HCC by histologic examination were included. HCC and corresponding adjacent tissues (distance from the tumor border exceeding 2 cm) were obtained. Twenty-three samples of normal liver tissue were acquired surgically from the patients who had received an operation due to liver trauma. CXCR2 mRNA and protein expressions were examined using semiquantitative reverse transcription-PCR and Western blot.

RESULTS

Expression levels of CXCR2 were significantly increased in HCC compared with adjacent and normal liver tissues (P < 0.05). The results showed that CXCR2 mRNA and protein expression levels were not related to age, gender, AFP levels, tumor capsule, or tumor size. Also, there was no relationship between CXCR2 mRNA expression and TNM staging. The expression levels of CXCR2 mRNA and protein were correlated with intrahepatic metastasis (P < 0.05), portal cancer embolus (P < 0.05), and low differentiation (P < 0.05). Furthermore, the protein level of CXCR2 was relevant to TNM staging. The protein level of CXCR2 in stage III-IV was remarkably higher than in stage I-II (P < 0.05).

CONCLUSION

Our data revealed that CXCR2 was able to promote invasion and metastasis of HCC. It may be a useful marker for judging biocharacteristics and prognosis of HCC.

Interleukin-13 exerts autocrine growth-promoting effects on human pancreatic cancer, and its expression correlates with a propensity for lymph node metastases

BACKGROUND AND AIMS

Interleukin-13 (IL-13) is an anti-inflammatory cytokine produced in cells of hematopoetic origin. It is not known whether pancreatic cancer cells produce IL-13 or whether IL-13 can modulate pancreatic cancer cell growth and influence the frequency of lymph node metastases.

MATERIALS AND METHODS

Cell growth and signaling were analyzed by cell counting, colorimetric proliferation assays, fluorescent-activated cell sorting, and in vitro kinase activity assays. IL-13 expression and secretion were determined by Northern blot analysis and enzyme-linked immunosorbent assay, respectively. Localization of IL-13 and its transmembrane receptor (IL-4R) in primary pancreatic ductal adenocarcinoma (PDAC) was characterized by immunohistochemistry.

RESULTS

IL-13 enhanced the growth of ASPC-1, CAPAN-1, and COLO-357 cells. This was associated with enhanced p44/42 mitogen-activated protein kinase (MAPK) phoshorylation. In contrast to p44/42 MAPK, phosphatidylinositol 3-kinase activity was also induced in IL-13-unresponsive MIA PaCa-2, PANC-1, and T3M4 cells. All cells expressed and secreted IL-13. Neutralizing IL-13 antibodies inhibited the growth of ASPC-1 and CAPAN-1 cells. Immunohistochemical analysis of resected primary ductal adenocarcinoma specimens revealed high levels of IL-13 in 30 of 70 cases and its transmembrane receptor (IL-4R) in 28 of 70 cases, respectively. Fifteen of 16 specimens (94%) exhibiting high IL-13 and IL-4R coexpression had lymph node metastases, while only 30 of the remaining 54 samples (56%) had positive lymph nodes (p = 0.0134).

CONCLUSION

IL-13 can act as an autocrine growth factor in PDAC. Endogenous expression of IL-13 in conjunction with IL-4R in the cancer cells seems to facilitate lymph node metastasis.

Control of chemokine gradients by the retinal pigment epithelium

PURPOSE

Proinflammatory cytokines in degenerative diseases can lead to the loss of normal physiology and the destruction of surrounding tissues. In the present study, the physiological responses of human fetal retinal pigment epithelia (hfRPE) were examined in vitro after polarized activation of proinflammatory cytokine receptors.

METHODS

Primary cultures of hfRPE were stimulated with an inflammatory cytokine mixture (ICM): interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma. Western blot analysis and immunofluorescence were used to determine the expression/localization of the cytokine receptors on hfRPE. Polarized secretion of cytokines was measured. A capacitance probe technique was used to measure transepithelial fluid flow (J(V)) and resistance (R(T)).

RESULTS

IL-1R1 was mainly localized to the apical membrane and TNFR1 to the basal membrane, whereas IFN-gammaR1 was detected on both membranes. Activation by apical ICM induced a significant secretion of angiogenic and angiostatic chemokines, mainly across the hfRPE apical membrane. Addition of the ICM to the basal but not the apical bath significantly increased net fluid absorption (J(V)) across the hfRPE within 20 minutes. Similar increases in J(V) were produced by a 24-hour exposure to ICM, which significantly decreased total R(T).

CONCLUSIONS

Chemokine gradients across the RPE can be altered (1) through an ICM-induced change in polarized chemokine secretion and (2) through an increase in ICM-induced net fluid absorption. In vivo, both of these factors could contribute to the development of chemokine gradients that help mediate the progression of inflammation/angiogenesis at the retina/RPE/choroid complex.

Erythrocyte CD38 as a prognostic marker in cancer

BACKGROUND

Surface antigen CD38 which is a multifunctional protein with enzymatic and receptorial properties is involved in many processes of cell proliferation and activation. It is widely expressed within the hematopoetic system, and its expression is stimulated by proinflammatory cytokines. CD38-associated enzymatic activities in erythrocytes from cancer patients were investigated in this context.

METHODS

Erythrocyte NAD glycohydrolase and ADP-ribosyl cyclase activities in normal individuals and cancer patients were compared and correlation of these activities to CEA values and anemia were determined. Changes in CD38-expression were followed by SDS-PAGE and Western blot analysis of erythrocyte membrane proteins.

RESULTS

Erythrocyte NAD glycohydrolase and ADP-ribosyl cyclase activities were significantly increased in cancer, in parallel to enhancement of CD38 expression and in correlation with CEA values and anemia.

CONCLUSIONS

An increased expression of CD38 which may be due to action of proinflammatory cytokines produced in tumor-host reactions appears to account for the elevations in erythrocyte CD38-associated enzyme activities in cancer patients. The changes in these enzyme activities may provide a prognostic outlook in view of their apparently close correlation to tumor progressions.

Targeting angiogenesis in pancreatic cancer: rationale and pitfalls

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer responsible for over 20% of deaths due to gastrointestinal malignancies. PDAC is usually diagnosed at an advanced stage which, in part, helps to explain its high resistance to chemotherapy and radiotherapy. In addition, the cancer cells in PDAC have a high propensity to metastasize and to aberrantly express several key regulators of angiogenesis and invasion. Chemotherapy has only provided a modest impact on mean survival and often induces side effects. Targeting angiogenesis alone or in combination with other modalities should be investigated to determine if it may provide for increased survival.

MATERIALS AND METHODS

This review summarizes the alterations in PDAC that play a critical role in angiogenesis and provides an overview of current and therapeutic strategies that may be useful for targeting angiogenesis in this malignancy.

CXCL14 expression and potential function in pancreatic cancer

CXC chemokines influence angiogenesis, growth, and metastatic potential of pancreatic cancer. Therefore, the expression and potential function of CXCL14, a recently described CXC chemokine, was evaluated. CXCL14 is upregulated in pancreatic cancer tissues compared to chronic pancreatitis and normal pancreas. Immunolocalization revealed a distinct expression of CXCL14 in tubular complexes in chronic pancreatitis and in particular at the invasive front of pancreatic cancer tissues. Stimulation of pancreatic cancer cells with CXCL14 showed no effects on cell viability and on chemosensitivity. However, CXCL14 clearly increased invasiveness of pancreatic cancer cells without affecting MMP-2 and VEGF secretion, whereas CXCL14 influenced NFkB p65 levels. In conclusion, CXCL14 might play a pivotal role in the pathobiology of pancreatic cancer, probably by regulating cancer invasion.

Prediction of lymph node metastasis in colorectal carcinoma by expressionof chemokine receptor CCR7

Chemokine receptors are known to regulate homing of lymphocytes into secondary lymphoid organs and may also be involved in the lymphatic spread of solid tumors. Therefore, the assessment of chemokine receptor expression on colorectal carcinomas could potentially improve the prediction of lymph node spread. This is of great importance for the selection of patients for local therapy without the need for concomitant lymphatic dissection. Currently, only 5% of all patients can be selected for this desirable treatment option by established prognosticators. In a retrospective study, expression levels of the chemokine receptors CCR7, CXCR4 and CXCR5 were determined by immunohistochemistry on paraffin-embedded specimens of 99 colorectal carcinomas, which were curatively operated on, comprising all stages of the disease. Receptor expressions (absent vs. positive) from the overall tumor (OT) and from the invasion front (IF) including further prognosticators were correlated with lymph node status by uni- and multivariate analysis. Data were also correlated with synchronous distant metastases and overall survival. Median follow-up was 64 months. In univariate analysis, lymph node status correlated significantly with lymphovascular invasion, the expression of CCR7 IF, CCR7 OT, CXCR4 IF and CXCR4 OT, as well as pT category. Multivariate analysis revealed a significant correlation of lymph node status with lymphovascular invasion and CCR7 IF expression level. Most interestingly, CCR7 IF expression was significantly linked to decreased survival. CCR7 plays an important role in the mechanism of lymph node spread in colorectal carcinoma. Evaluation of the chemokine receptor expression profile seems to be appropriate to improve the selection of patients suited for local treatment and might constitute targets for nonsurgical therapy.

Macrophage inflammatory protein-3alpha promotes pancreatic cancer cell invasion

BACKGROUND

Human CC chemokine Macrophage Inflammatory Protein-3alpha (MIP-3alpha) directs inflammatory cell migration through its binding to the transmembrane receptor CCR6. MIP-3alpha has recently been shown to promote tumor cell migration in pancreatic adenocarcinoma by up-regulation of matrix metalloproteinases (MMPs). We hypothesized that MIP-3alpha promotes pancreatic cancer invasion through the up-regulation of MMP-9, a Type 4 collagenase.

MATERIALS, METHODS, AND RESULTS

Immunohistochemistry and RT-PCR confirmed the presence of MIP-3alpha in PANC-1 cells, a human pancreatic adenocarcinoma cell line. MIP-3alpha stimulated the production of both latent and active forms of MMP-9 in PANC-1 by Western analysis. Tumor cell invasion was then evaluated using a modified Boyden chamber invasion assay. MIP-3alpha promoted a dose-dependent increase in pancreatic cancer cell invasion (P < 0.05) at 100 ng/ml. The activity at the putative MIP-3alpha receptor, CCR6, was demonstrated by receptor blockade. Anti-CCR6 antibody and anti-MMP-9 antibody inhibited MIP-3alpha-stimulated PANC-1 cell invasion of collagen to 37% and 35% of control, respectively (P < 0.05).

CONCLUSIONS

MIP-3alpha, through its CCR6 receptor, promotes tumor cell invasion by the up-regulation of MMP-9. Molecular based therapy aimed at the inhibition of MIP-3alpha activity through the CCR6 receptor may serve as a future target to prevent tumor cell invasion in pancreatic adenocarcinoma.

cCXCR1 is a receptor for cIL-8 (9E3/cCAF) and its N- and C-terminal peptides and is also activated by hIL-8 (CXCL8)

Chemokines are chemotactic cytokines that play important roles in immune responses and wound healing, as well as in pathological conditions such as chronic inflammation and tumorigenesis. The chemokines and their receptors are highly conserved and maintain similar functions in different species. One noteworthy exception is the chemokine interleukin (IL)8/CXC ligand 8 and its specific receptor CXCR1, which are found in humans but are not found in the traditional model organisms, mice and rats. As a consequence, we are using model organisms other than mice to study the functions of IL-8 and CXCR1, as well as the mechanisms involved in receptor activation by IL-8. Toward this goal, we have isolated and characterized a new receptor that is highly homologous to human (h)CXCR1, which we named chicken (c)CXCR1. To determine whether this receptor is activated by cIL-8 and its N- and C-terminal peptides and whether it responds to hIL-8, we expressed cCXCR1 in NIH3T3 cells, which naturally lack this receptor, and used single-cell Ca(2)(+) imaging to detect increases in intracellular Ca(2)(+) and immunoblot analysis to detect extracellular signal-regulated kinase 1/2 phosphorylation. We show that cIL-8, its N and C peptides, and hIL-8 activate cCXCR1. We further show that cIL-8 and hIL-8 stimulate chemotaxis of chicken embryonic fibroblasts, cells that express cCXCR1, and that this effect is specific for each chemokine and this receptor. These results strongly suggest that cCXCR1 is the ortholog for hCXCR1 and that chickens can be used as an effective model system to study the functions of IL-8, its terminal peptides, and its specific receptor CXCR1.

Involvement of stromal proteoglycans in tumour progression

Glycosaminoglycans (GAGs) and proteoglycans (PGs) belong to a class of extracellular macromolecules necessary for the growth of any multicellular structures, including tumours. Transformed cells induce stromal reaction either per se or by activation of the mesenchymal cells. Tumour stroma contains several chondroitin sulphate and heparan sulphate proteoglycans. These proteoglycans and their glycosaminoglycan chains modify cell behaviour by interacting with different molecules such as growth factors, cytokines, chemokines, proteinases and their inhibitors. This review describes the main proteoglycans of tumour stoma and discusses their implication in the regulation of the activity of extracellular proteins and peptides.

High-level expression of functional chemokine receptor CXCR4 on human neural precursor cells

Neural precursor cells (NPCs) are self-renewing, multipotent progenitors that give rise to neurons, astrocytes and oligodendrocytes in the central nervous system (CNS). Fetal NPCs have attracted attention for their potential use in studying normal CNS development. Several studies of rodent neural progenitors have suggested that chemokines and their receptors are involved in directing NPC migration during CNS development. In this study, we established a consistent system to culture human NPCs and examined the expression of chemokine receptors on these cells. NPCs were found to express the markers nestin and CD133 and to differentiate into neurons, astrocytes and oligodendrocytes at the clonal level. Flow cytometry and RNase protection assay (RPA) indicated that NPCs express high levels of CXCR4 and low levels of several other chemokine receptors. When examined using a chemotaxis assay, NPCs were able to respond to CXCL12/SDF-1alpha, a ligand of CXCR4. Treatment with anti-CXCR4 antibody or HIV-1 gp120 abolished the migratory response of NPCs towards CXCL12/SDF-1alpha. These findings suggest that CXCR4 may play a significant role in directing NPC migration during CNS development.

Inflammatory mechanisms contributing to pancreatic cancer development

OBJECTIVE

Pancreatic cancer is the most deadly of all gastrointestinal (GI) malignancies, yet relatively little is known regarding mechanisms of tumor development including the role of inflammation.

SUMMARY BACKGROUND DATA

Chronic pancreatitis (CP) increases the risk of developing cancer by 10- to 20-fold; mediators of the chronic inflammatory process and the surrounding fibrotic stroma likely support a transformation to malignancy, yet the exact mechanisms remain undefined. The purpose of our present study was to determine potential inflammatory components in epithelial and stromal cells that may contribute to both CP and pancreatic cancers.

METHODS

Specimens of normal pancreas, CP, and pancreatic cancer were examined using laser-capture microdissection (LCM), gene array, and immunohistochemistry.

RESULTS

Gene array analysis from LCM-dissected tissues demonstrated: (i) increased expression of interleukin-8 (IL-8), an activator of the inflammatory factor nuclear factor-kappaB (NF-kappaB), and (ii) decreased expression of IkappaB (an inhibitor of NF-kappaB) in CP ductal cells compared with normal ducts. Compared with CP, cancers demonstrated: (i) increased expression of tumor related genes including S100A4, cyclin E1, and epidermal growth factor (EGF) receptor, and (ii) expression of matrix metalloproteinase 2, a pro-invasive factor for tumor cells, which was not present in the CP stroma. Increased staining of both the p50 NF-kappaB subunit and IKKalpha kinase (a protein that allows activation of NF-kappaB) was noted in CP and cancers.

CONCLUSIONS

Our results demonstrate that similar inflammatory components and downstream effectors are present in CP and pancreatic cancers. Importantly, these findings suggest that a common pathway for pancreatic cancer development may be through a chronic inflammatory process including stroma formation. These findings may lead to novel strategies for pancreatic cancer prophylaxis based on inhibition of inflammatory mediators.