Effect of IL-6 overexpression on the metastatic potential of rat hepatocellular carcinoma cells

Interleukin-6 as a biomarker in patients with hepatobiliary cancers

Background

The role of inflammation has been well established in many cancers, including hepatobiliary cancers. Elevated levels of interleukin-6 (IL-6), a pro-inflammatory marker, are associated with poor overall survival (OS) in hepatocellular carcinoma (HCC) patients.

Methods

We performed a study to establish the role of IL-6 as a prognostic biomarker in both HCC and biliary cancer patients and further assessed the impact of IL-6 on pain score and performance status, two parameters that affect the quality of life. We evaluated 91 patients with newly diagnosed unresectable hepatobiliary cancer and compared them with age, gender and BMI matched healthy controls.

Results

We found that IL-6 levels were elevated in hepatobiliary cancer patients compared to healthy controls. Higher levels of IL-6 were associated with poor prognosis, elevated pain scores and poor performance status in patients. Interestingly, we found an association between elevated IL-6 levels and the presence of portal vein thrombosis (PVT) at the time of cancer diagnosis.

Conclusions

This study suggests that IL-6 is an important prognostic biomarker in hepatobiliary cancers, where elevated levels are not only associated with a worse survival but also linked to an inferior quality of life.

Hypoxia-induced HMGB1 expression of HCC promotes tumor invasiveness and metastasis via regulating macrophage-derived IL-6

Hypoxia is associated with the progression of hepatocellular carcinoma through promotion of spontaneous metastasis but the mechanism remains unclear. Here, we hypothesis that tumor cell-derived HMGB1 orchestrates macrophages infiltration and promotes metastasis of HCC via enhancing macrophage-secreted IL-6 under hypoxia. HMGB1 expression was robustly exacerbated in tumors of HCC patients with PVTT. Meanwhile, hypoxia exposure gave rise to HMGB1 expression in hepatoma cells of human and mouse in a HIF-1α-dependent manner and subsequently induced the infiltration and reprogramming of macrophages to augment the expression of Il-6. Further study demonstrated macrophage-derived IL-6 enhanced the invasiveness and metastasis of murine HCC cells. Therefore, our study provides a novel understanding of the relationship between tumor cells and tumor associated macrophages (TAMs) in the context of hypoxia.

Components of the Hepatocellular Carcinoma Microenvironment and Their Role in Tumor Progression

This review summarizes recently published data on the mechanisms of tumor cell interaction with the tumor microenvironment. Tumor stroma influences the processes of hepatocarcinogenesis, epithelial-to-mesenchymal transition, invasion, and metastasis. The tumor microenvironment includes both cellular and noncellular components. Main cellular components of hepatocellular carcinoma (HCC) stroma are tumor-associated fibroblasts, hepatic stellate cells, immune cells, and endothelial cells that produce extracellular components of tumor microenvironment such as extracellular matrix, various proteins, proteolytic enzymes, growth factors, and cytokines. The noncellular components of the stroma modulate signaling pathways in tumor cells and stimulate invasion and metastasis. The tumor microenvironment composition and organization can serve as prognostic factors in HCC pathogenesis. Current approaches in HCC targeted therapy are aimed at creating efficient strategies for interrupting tumor interactions with the stroma. Recent data on the composition and role of the microenvironment in HCC pathogenesis, as well as new developments in antitumor drug design are discussed.

Microencapsulation of Engineered Cells to Deliver Sustained High Circulating Levels of Interleukin-6 to Study Hepatocellular Carcinoma Progression

Interlukin-6 (IL-6) is a pleitropic cytokine that plays a central role in normal and abnormal hepatic function and response. The aims of the current study were to determine the viability of using cell encapsulation technology to introduce a genetically modified xenogeneic (CHO) cell population to elevate circulating levels of rhIL-6 in a rat model and determine the effects of sustained high rhIL-6 levels on hepatocellular carcinoma (HCC) progression in vivo. An alginate matrix was combined with transfected CHO cells, selected for their ability to synthesize rhIL-6, and used to generate uniform alginate–cell beads. Once encapsulated transfected cells continued to undergo replication, formed colonies within the bead, and synthesized/released large quantities of rhIL-6 into culture medium in vitro. Intraperitoneal implantation of beads into rats resulted in significantly increased circulating and intrahepatic levels of rhIL-6 up to 4 days postimplantation. Prolonged implantation led to the escape of CHO cells from the bead, resulting in a host response and CHO cell death within the bead. Subsequently CHO-IL-6 encapsulated cells were implanted into rats previously inoculated intrahepatically with the H4IIE HCC cell line. These studies demonstrated the maintenance of high circulating/intrahepatic rhIL-6 levels in this model. Despite significantly increased rhIL-6, this technique did not significantly alter the rate of net tumor progression. However, Stat3 activity was significantly increased in both normal liver and HCC tissue resected from animals implanted with CHO-IL-6 cells. Collectively these data demonstrate the short-term viability of using cell encapsulation technology to generate high levels of active circulating and intrahepatic cytokines and raise the possibility of modifying specific signal transduction cascades identified to be important during tumor progression.

Na+/H+ exchanger 1, Na+/Ca2+ exchanger 1 and calmodulin complex regulates interleukin 6-mediated cellular behavior of human hepatocellular carcinoma

Interleukin 6 (IL6) is a key cytokine involved in the development and progression of inflammation-associated hepatocellular carcinoma (HCC). However, the mechanisms of IL6 action on HCC remain largely unknown. Proton and Ca(2+) are two intracellular messenger ions, which are believed to play a central role in tumorigenesis and tumor progression. In this study, we found that IL6 stimulation markedly increased intracellualr pH recovery rates of human HCC cells, Huh7 and HepG2, after NH4Cl acidification, and the NH4Cl acidification induced transient intracellular Ca(2+) increases in the HCC cells. The inhibition of Na(+)/H(+) exchanger 1 (NHE1), Na(+)/Ca(2+) exchanger 1 (NCX1) and calmodulin (CaM) inhibited the IL6 stimulation-induced intracellular pH recovery increases and NH4Cl acidification-induced intracellular Ca(2+) increases. IL6 stimulation also induced the structural interaction of NHE1, NCX1 and CaM proteins. The protein expression levels of NHE1, NCX1 and CaM in native human HCC tissues were markedly higher than those in normal liver tissues. IL6 upregulated the expressions of NHE1, NCX1 and CaM in Huh7 and HepG2 cells. NHE1, NCX1 and CaM mediated the promotion of IL6 on the proliferation, migration and invasion of Huh7 and HepG2 cells and the growth of HCC in nude mice. In conclusion, IL6 activates the functional activity of NHE1 and induces the functional and structural interaction of NHE1, NCX1 and CaM. The interaction of NHE1, NCX1 and CaM mediates the effects of IL6 on human HCC.

Rather than Rs1800796 polymorphism, expression of interleukin-6 is associated with disease progression of chronic HBV infection in a Chinese Han population

Interleukin-6 plays an important role in chronic inflammation as well as tumor growth and progression. Here, a case-control study was undertaken to investigate the association of rs1800796 polymorphism of IL-6 gene and serum levels with disease progression of chronic HBV infection. Rs1800796 polymorphism was genotyped in 641 Chinese Han patients with chronic HBV infection, including 23 IT, 25 IC, 292 CHB, 153 LC, and 148 HCC patients and 265 healthy controls. Serum IL-6 levels were measured in 23 IT, 25 IC, 47 CHB, 41 LC, and 49 HCC patients and 45 healthy controls, and the classifications of HCC were accorded to BCLC staging system. We found no significant association between rs1800796 polymorphism and disease progression of chronic HBV infection; however, serum IL-6 levels showed significant statistical differences between patients with CHB, LC, and HCC. Moreover, statistical differences can be observed in patients with terminal stage HCC compared with those of early to intermediate or advanced stage HCC. Our findings suggest that rs1800796 polymorphism unlikely contribute significantly to affect the progression of chronic HBV infection, and serum IL-6 levels can act as a useful indicator for disease progression and severity of chronic HBV infection.

The inflammatory microenvironment in hepatocellular carcinoma: a pivotal role for tumor-associated macrophages

Hepatocellular carcinoma (HCC) is one of the most common and aggressive human cancers worldwide. HCC is an example of inflammation-related cancer and represents a paradigm of the relation occurring between tumor microenvironment and tumor development. Tumor-associated macrophages (TAMs) are a major component of leukocyte infiltrate of tumors and play a pivotal role in tumor progression of inflammation-related cancer, including HCC. Several studies indicate that, in the tumor microenvironment, TAMs acquire an M2-polarized phenotype and promote angiogenesis, metastasis, and suppression of adaptive immunity through the expression of cytokines, chemokines, growth factors, and matrix metalloproteases. Indeed, an established M2 macrophage population has been associated with poor prognosis in HCC. The molecular links that connect cancer cells and TAMs are not completely known, but recent studies have demonstrated that NF-κB, STAT-3, and HIF-1 signaling pathways play key roles in this crosstalk. In this paper, we discuss the current knowledge about the role of TAMs in HCC development, highlighting the role of TAM-derived cytokines, chemokines, and growth factors in the initiation and progression of liver cancer and outlining the signaling pathways involved in the interplay between cancer cells and TAMs.

Serum interleukin-6 and C-reactive protein as a prognostic indicator in hepatocellular carcinoma

The development of hepatocellular carcinoma (HCC) is often associated with chronic inflammation, suggesting a strong relationship between inflammation and carcinogenesis. This study evaluated the prognostic values of inflammatory and T-helper (Th) cytokines in the clinical outcome and survival of HCC. The study included 110 patients with HCC undergoing loco-regional therapy and 24 healthy controls. Five Th1/Th2 cytokines and C-reactive protein (CRP) were quantified before and after loco-regional treatment, using enzyme-linked immunosorbent assays. Levels of CRP, interleukin (IL)-4, and IL-6 were higher in patients with HCC than those in healthy subjects. Tumor characteristics, Child-Pugh class, and CRP, IL-6, and IL-10 levels were associated with HCC survival (all P<0.05). With multivariate analysis, higher IL-6 levels were identified as the independent cytokine for shorter survival (P=0.010). Higher CRP and IL-6 levels correlated well with larger tumor size, poor Child-Pugh function, and shorter survival, with a significant inter-correlation (r=0.667). On serial measurements, the association of CRP with tumor response was stronger than that of α-fetoprotein or other cytokines. IL-6 and CRP are strong inflammatory indicators predictive of outcome in patients with HCC receiving loco-regional therapy. This study suggests that inflammatory activation of the IL-6/CRP network may be a potential therapeutic target and biomarker for HCC.

Circulating interleukin-6 as a tumor marker for hepatocellular carcinoma

BACKGROUND

A large amount of evidence suggests a possible role of interleukin-6 (IL-6) in the pathogenesis of hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

We studied both IL-6 and A(1)FP in patients with HCC, non-neoplastic liver disease or in healthy controls.

RESULTS

IL-6 titers were four-fold higher in cancer than in cirrhotic patients and 25-fold higher than in healthy controls. As for alpha1-fetoprotein (A(1)FP) titers, the highest levels were observed in cancer patients. Receiver operating characteristic (ROC) curves analysis demonstrated that IL-6 is significantly more discriminant than A(1)FP, with 'optimal' cut-off values of 7.9 pg/ml (sensitivity = 0.83, specificity = 0.83, efficiency = 0.83). The ROC curves used to distinguish HCC from cirrhotic patients only, showed higher discriminant power of IL-6 versus A(1)FP titers, with a new cut-off value of 12 pg/ml (sensitivity = 0.73, specificity = 0.87, efficiency = 0.8). Discriminant analysis on HCC and non-HCC subjects yielded sensitivity, specificity and efficiency rates of 77%, 93% and 88%, respectively. The overall efficiency of the two tests combined was 82%.

CONCLUSIONS

IL-6 could be considered a promising tumor marker for HCC. In particular, the diagnostic value of the test is significantly increased when combined with A(1)FP.

Evaluation of interleukin-6, interleukin-10 and human hepatocyte growth factor as tumor markers for hepatocellular carcinoma

AIM

Serum alpha-fetoprotein (AFP) is the most important tumor marker for hepatocellular carcinoma (HCC). Previous reports indicated that HCC was also associated with increased levels of interleukin (IL)-6, IL-10 and hepatocyte growth factor (HGF). This study investigated the role of these cytokines as tumor markers for HCC.

METHOD

A total of 128 adults were prospectively enrolled and categorized into four groups: normal subjects (n=29), chronic hepatitis B or C (n=50), non-HCC tumors (n=23) and HCC (n=26). Serum AFP, IL-6, IL-10 and HGF levels were determined in all subjects.

RESULTS

The expression of IL-6 or IL-10 (> or =3 pg/ml), or high level of HGF (>1000 pg/ml) or AFP (>20 ng/ml) was observed in only 0-3% of normal subjects. Patients with HCC more frequently had higher IL-6 and IL-10 levels (p<0.05), whereas HGF levels in HCC patients were not significantly elevated compared to patients with chronic hepatitis or non-HCC tumors. Among patients with low (<20 ng/ml) AFP level, IL-6 or IL-10 expression was significantly associated with the existence of HCC (p<0.05). Patients with large (>5 cm) HCC more often had increased IL-6, IL-10 or AFP levels (p values all <0.05).

CONCLUSIONS

Serum levels of IL-6 and IL-10 are frequently elevated in patients with HCC but not in benign liver disease or non-HCC tumors. IL-6 and IL-10 may help identify a subset of HCC patients with low AFP level, and may serve as complementary tumor markers in these patients.

The role of cytokines in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a frequent malignancy worldwide with a high rate of metastasis. The hepatitis B and C viruses are considered major etiological factors associated with the development of HCC, particularly as a result of their induction of chronic inflammation. There is increasing evidence that the inflammatory process is inherently associated with many different cancer types, including HCC. Specifically, this review aims to cover evidence for the potential roles of cytokines, an important component of the immune system, in promoting HCC carcinogenesis and progression. A global summary of cytokine levels, functions, polymorphisms, and therapies with regard to HCC is presented. In particular, the role of proinflammatory Th1 and anti-inflammatory Th2 cytokine imbalances in the microenvironment of HCC patients with metastasis and the possible clinical significance of these findings are addressed. Overall, multiple studies, spanning many decades, have begun to elucidate the important role of cytokines in HCC.

New developments in IL-6 dependent biology and therapy: where do we stand and what are the options?

Interleukin-6 (IL-6) is a four-helical protein which, on target cells, binds to a specific IL-6-receptor and two molecules of the promiscuous signal transducing protein gp130. Structure-function analysis defined three molecular contact sites between IL-6 and its receptor subunits. Using this information, competitive antagonistic proteins as well as hyperagonistic proteins were developed. Possible therapeutic applications of IL-6 antagonists are in IL-6 dependent haematological disorders (Castleman's disease, POEMS syndrome, multiple myeloma) and bone diseases (Paget's disease, osteoporosis). Designer IL-6 antagonists could suppress inflammatory activity in rheumatic and autoimmune diseases and could prevent secondary amyloidosis. IL-6 antagonists could also prove advantageous in myocardial infarction and unstable angina pectoris. IL-6 antagonists might slow down development of (mesangioproliferative) glomerulonephritis. On the other hand, hyperagonistic variants of IL-6 have a potential in ex vivo expansion of bone marrow stem cells and as thrombopoietic agents. They might also be developed into drugs to support liver regeneration in vivo and to treat stress-induced cardiac insufficiency.

The role of transsignalling via the agonistic soluble IL-6 receptor in human diseases

The activation of cells that do not express the membrane bound interleukin-6 6 receptor (IL-6R) by IL-6 and the soluble IL-6 receptor (sIL-6R) is termed transsignalling. Transsignalling may be an pathogenetic factor in human diseases as diverse as multiple myeloma (MM), Castleman's disease, prostate carcinoma, Crohn's disease, systemic sclerosis, Still's disease, osteoporosis and cardiovascular diseases. IL-6 and sIL-6R may directly or indirectly enhance their own production on endothelial or bone marrow stromal cells. Positive feedback autocrine loops thus created in affected organs may either cause or maintain disease progression. In autoimmune or vasculitic disease, the ability of the IL-6/sIL-6R complex to inhibit apoptosis of autoreactive T-cells may be central to the development of tissue specific autoimmunity. The anti-apoptotic effect of the IL-6/sIL-6R complex may be involved in tumour genesis and resistance to chemotherapy. Only in rare cases, where counterregulation has failed, there is a notable systemic effect of IL-6/sIL-6R. Appropriate animal models are necessary to establish the pathogenetic role of the IL-6/sIL-6R complex. A specific treatment option for diseases influenced by the sIL-6R could be based on gp130-Fc, a soluble gp130 (sgp130) linked to the Fc-fragment of IgG1. gp130-Fc has shown efficacy in vivo in animal models of Crohn's disease.

Probing the cons and pros of lectin-induced immunomodulation: case studies for the mistletoe lectin and galectin-1

When imagining to monitor animal cells through a microscope with resolution at the molecular level, a salient attribute of their surfaces will be the abundance of glycan chains. They present galactosides at their termini widely extending like tentacles into the extracellular space. Their spatial accessibility and their potential for structural variability endow especially these glycan parts with capacity to act as docking points for molecular sensors (sugar receptors such as lectins). Binding and ligand clustering account for transmission of post-binding signals into the cell interior. The range of triggered activities has turned plant lectins into popular tools in cell biology and immunology. Potential for clinical application has been investigated rigorously only in recent years. As documented in vitro and in vivo for the galactoside-specific mistletoe lectin, its apparent immunomodulatory capacity reflected in upregulation of production of proinflammatory cytokines will not necessarily be clinically favorable but a double-edged sword. In fact, lectin application has been shown to stimulate tumor growth in cell lines, histocultures of human tumors and in two animal models using chemical carcinogenesis or tumor transplantation. When testing immunological effects of the endogenous lectin galectin-1, protection against disorders mediated by activated T cells came up for consideration. Elimination of these cells via CD7-dependent induction of apoptosis, and a shift to the Th2 response by the galectin, are factors to ameliorate disease states. This result encourages further efforts with other galectins. Functional redundancy, synergism, diversity or antagonism among galectins are being explored to understand the actual role of this class of endogenous lectins in inflammation. Regardless of the results of further preclinical testing for galectin-1, these two case studies break new ground in our understanding how glycans as ligands for lectins convey reactivity to immune cells, with impact on the course of a tumor or autoimmune disease.