Chemokine expression in hepatocellular carcinoma versus colorectal liver metastases

Immunotherapy for hepatocellular carcinoma: Current status and future perspectives

Hepatocellular carcinoma (HCC) is one of the world’s deadliest and fastest-growing tumors, with a poor prognosis. HCC develops in the context of chronic liver disease. Curative resection, surgery (liver transplantation), trans-arterial chemoembolization, radioembolization, radiofrequency ablation and chemotherapy are common treatment options for HCC, however, they will only assist a limited percentage of patients. Current treatments for advanced HCC are ineffective and aggravate the underlying liver condition. Despite promising preclinical and early-phase clinical trials for some drugs, existing systemic therapeutic methods for advanced tumor stages remain limited, underlining an unmet clinical need. In current years, cancer immunotherapy has made significant progress, opening up new treatment options for HCC. HCC, on the other hand, has a variety of causes and can affects the body’s immune system via a variety of mechanisms. With the speedy advancement of synthetic biology and genetic engineering, a range of innovative immunotherapies, such as immune checkpoint inhibitors [anti-programmed cell death-1 (PD-1), anti-cytotoxic T lymphocyte antigen-4, and anti-PD ligand 1 cell death antibodies], therapeutic cancer vaccines, engineered cytokines, and adoptive cell therapy have all been used for the treatment of advanced HCC. In this review, we summarize the present clinical and preclinical landscape of immunotherapies in HCC, critically discuss recent clinical trial outcomes, and address future perspectives in the field of liver cancer.

The Role of Cytokines in the Different Stages of Hepatocellular Carcinoma

Simple Summary

Non-homeostatic cytokine expression during hepatocellular carcinogenesis, together with simple and inexpensive cytokine detection techniques, has opened up its use as potential biomarkers, from cancer detection to prognosis. However, carcinogenic programs during cancer progression are not linear. Therefore, cytokines with prognostic potential in one stage may not be relevant in another. Here, we reviewed cytokines with clinical potential in different settings during hepatocellular carcinoma progression.

Abstract

Hepatocellular carcinoma (HCC) is the primary form of liver cancer and a leading cause of cancer-related death worldwide. Early detection remains the most effective strategy in HCC management. However, the spectrum of underlying liver diseases preceding HCC, its genetic complexity, and the lack of symptomatology in early stages challenge early detection. Regardless of underlying etiology, unresolved chronic inflammation is a common denominator in HCC. Hence, many inflammatory molecules, including cytokines, have been investigated as potential biomarkers to predict different stages of HCC. Soluble cytokines carry cell-signaling functions and are easy to detect in the bloodstream. However, its biomarkers’ role remains limited due to the dysregulation of immune parameters related to the primary liver process and their ability to differentiate carcinogenesis from the underlying disease. In this review, we discuss and provide insight on cytokines with clinical relevance for HCC differentiating those implicated in tumor formation, early detection, advanced disease, and response to therapy.

Chemokines in hepatocellular carcinoma: a meta-analysis

Accumulating evidence suggests that chemokines may play an important role in the formation and mediating of the immune microenvironment of hepatocellular carcinoma (HCC). The purpose of this meta-analysis was to explore the differences in blood or tissues chemokines concentrations between HCC patients and controls. Online databases, namely PubMed, Web of Science, Embase and Cochrane Library, were systematically searched for relevant articles published on or before 15 January 2020. Standardized mean differences (SMDs) with corresponding 95% confidence intervals of the chemokines concentrations were calculated as group differences between the HCC patients and the controls. Sixty-five studies met the inclusion criteria for the meta-analysis. Altogether they consisted of 26 different chemokines compared between 5828 HCC patients and 4909 controls; and 12 different chemokines receptors compared between 2053 patients and 2285 controls. The results of meta-analysis indicated that concentrations of CCL20, CXCL8 and CXCR4 in the HCC patients were significantly higher than those in the controls (SMD of 6.18, 1.81 and 1.04, respectively). Therefore, higher concentration levels of CCL20, CXCL8 and CXCR4 may indicate the occurrence of HCC Future research should explore the putative mechanisms underlying this linkage. Meanwhile, attempts can be made to replicate the existing findings in prospective cohort populations and explore the cause-and-effect relationships pertaining to this linkage in order to develop new diagnostic and therapeutic strategies for HCC.

Immune Cell Trafficking to the Liver

The human liver is an organ with a diverse array of immunologic functions. Its unique anatomic position that leads to it receiving all the mesenteric venous blood, combined with its unique micro anatomy, allows it to serve as a sentinel for the body's immune system. Hepatocytes, biliary epithelial cells, Kupffer cells, stellate cells, and liver sinusoidal endothelial cells express key molecules that recruit and activate innate and adaptive immunity. Additionally, a diverse array of lymphoid and myeloid immune cells resides within and traffics to the liver in specific circumstances. Derangement of these trafficking mechanisms underlies the pathophysiology of autoimmune liver diseases, nonalcoholic steatohepatitis, and liver transplantation. Here, we review these pathways and interactions along with potential targets that have been identified to be exploited for therapeutic purposes.

The Diagnostic Value of Chemokine/Chemokine Receptor Pairs in Hepatocellular Carcinoma and Colorectal Liver Metastasis

Chemokines and their receptors have been proposed to play important roles in tumor progression and metastasis. To investigate their roles in the progression of primary and metastatic malignant liver tumors and their prognosis, we compared expression profiles of CXCL12/CXCR4, CCL20/CCR6, and CCL21/CCR7 in hepatocellular carcinoma (HCC) and colorectal liver metastases (CRLM). Immunohistochemistry was used to analyze the expression levels of the chemokine/chemokine receptor pairs in 29 HCC and 11 CRLM specimens and adjacent non-cancerous tissues, and correlations with clinicopathological variables and overall survival were determined. CCL20/CCR6 expression was higher in HCC than in adjacent non-cancerous tissues. High CCR6 expression in HCC was negatively associated with 5-year survival rate and was an independent prognostic factor for overall survival of HCC patients, whereas differences were not observed between CRLM and adjacent tissues. Furthermore, significantly higher expression of CCL21/CCR7 was found in CRLM than in HCC. In summary, the CCL20/CCR6 axis was elevated in HCC but not in CRLM, whereas the CCL21/CCR7 axis was elevated in CRLM but not in HCC.

Somatostatin and CXCR4 chemokine receptor expression in hepatocellular and cholangiocellular carcinomas: tumor capillaries as promising targets

Background

Hepatocellular (HCC) and cholangiocellular carcinomas (CCC) display an exceptionally poor prognosis. Especially for advanced disease no efficient standard therapy is currently available. Recently, somatostatin analogs have been evaluated for the treatment of HCC, however, with contradictory results. Besides, for both malignancies the chemokine receptor CXCR4 has been discussed as a possible new target structure.

Methods

Expression of somatostatin receptor (SSTR) subtypes 1, 2A, 3, 4, and 5, and of CXCR4 was evaluated in a total of 71 HCCs and 27 CCCs by immunohistochemistry using well-characterized novel monoclonal antibodies.

Results

In HCC tumor cells, frequency and intensity of expression of SSTRs and CXCR4 were only low. CXCR4 was present in about 40% of the HCCs, although at a low intensity. SSTR5, SSTR2, and SSTR3 were detected in about 15%, 8%, and 5% of the HCC tumors, respectively. SSTR and CXCR4 expression was much higher in CCC than in HCC. CXCR4 and SSTR1 were present in 60% and 67% of the CCC samples, respectively, followed by SSTR2 and SSTR5, which were detected in 30% and 11% of the tumors, respectively. Most notably, CXCR4 was intensely expressed on the tumor capillaries in about 50% of the HCCs and CCCs. CXCR4 expression on tumor vessels was associated with poor patient outcomes.

Conclusions

CCC, but not HCC, may be suitable for SSTR-based treatments. Because of the predominant expression of SSTR1, pan-somatostatin analogs should be preferred. In both HCC and CCC, indirect targeting of tumors via the CXCR4-positive tumor capillaries may represent a promising additional therapeutic strategy.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3911-3) contains supplementary material, which is available to authorized users.

Estimating genome-wide regulatory activity from multi-omics data sets using mathematical optimization

Background

Gene regulation is one of the most important cellular processes, indispensable for the adaptability of organisms and closely interlinked with several classes of pathogenesis and their progression. Elucidation of regulatory mechanisms can be approached by a multitude of experimental methods, yet integration of the resulting heterogeneous, large, and noisy data sets into comprehensive and tissue or disease-specific cellular models requires rigorous computational methods. Recently, several algorithms have been proposed which model genome-wide gene regulation as sets of (linear) equations over the activity and relationships of transcription factors, genes and other factors. Subsequent optimization finds those parameters that minimize the divergence of predicted and measured expression intensities. In various settings, these methods produced promising results in terms of estimating transcription factor activity and identifying key biomarkers for specific phenotypes. However, despite their common root in mathematical optimization, they vastly differ in the types of experimental data being integrated, the background knowledge necessary for their application, the granularity of their regulatory model, the concrete paradigm used for solving the optimization problem and the data sets used for evaluation.

Results

Here, we review five recent methods of this class in detail and compare them with respect to several key properties. Furthermore, we quantitatively compare the results of four of the presented methods based on publicly available data sets.

Conclusions

The results show that all methods seem to find biologically relevant information. However, we also observe that the mutual result overlaps are very low, which contradicts biological intuition. Our aim is to raise further awareness of the power of these methods, yet also to identify common shortcomings and necessary extensions enabling focused research on the critical points.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0419-z) contains supplementary material, which is available to authorized users.

NF-κB-Mediated CCL20 Reigns Dominantly in CXCR2-Driven Ovarian Cancer Progression

Ovarian cancer is an inflammation-associated malignancy with a high mortality rate. CXCR2 expressing ovarian cancers are aggressive with poorer outcomes. We previously demonstrated that CXCR2-driven ovarian cancer progression potentiated NF-κB activation through EGFR-transactivated Akt. Here, we identified the chemokine signature involved in CXCR2-driven ovarian cancer progression using a mouse peritoneal xenograft model for ovarian cancer spreading with CXCR2-negative (SKA) and positive (SKCXCR2) cells generated previously from parental SKOV-3 cells. Compared to SKA bearing mice, SKCXCR2 bearing mice had the following characteristics: 1) shorter survival time, 2) greater tumor spreading in the peritoneal cavity and 3) higher tumor weight in the omentum and pelvic site. Particularly, SKCXCR2-derived tumor tissues induced higher activation of the NF-κB signaling pathway, while having no change in EGFR-activated signaling such as Raf, MEK, Akt, mTOR and Erk compared to SKA-derived tumors. Chemokine PCR array revealed that CCL20 mRNA levels were significantly increased in SKCXCR2-derived tumor tissues. The CCL20 promoter activity was regulated by NF-κB dependent pathways. Interestingly, all three κB-like sites in the CCL20 promoter were involved in regulating CCL20 and the proximal region between -92 and -83 was the most critical κB-like site. In addition, SKCXCR2-derived tumor tissues maintained high CCL20 mRNA expression and induced greater CCL24 and CXCR4 compared to SKCXCR2 cells, indicating the shift of chemokine network during the peritoneal spreading of tumor cells via interaction with other cell types in tumor microenvironment. Furthermore, we compared expression profiling array between human ovarian cancer cell lines and tumor tissues based on GEO datasets. The expression profiles in comparison with cell lines revealed that dominant chemokines expressed in ovarian tumor tissues are likely shifted from CXCL1-3 and 8 to CCL20. Taken together, the progression of ovarian cancer in the peritoneal cavity involves NF-κB-mediated CCL20 as a main chemokine network, which is potentiated by CXCR2 expression.

Text mining, a race against time? An attempt to quantify possible variations in text corpora of medical publications throughout the years

BACKGROUND

The continuous growth of medical sciences literature indicates the need for automated text analysis. Scientific writing which is neither unitary, transcending social situation nor defined by a timeless idea is subject to constant change as it develops in response to evolving knowledge, aims at different goals, and embodies different assumptions about nature and communication. The objective of this study was to evaluate whether publication dates should be considered when performing text mining.

METHODS

A search of PUBMED for combined references to chemokine identifiers and particular cancer related terms was conducted to detect changes over the past 36 years. Text analyses were performed using freeware available from the World Wide Web. TOEFL Scores of territories hosting institutional affiliations as well as various readability indices were investigated. Further assessment was conducted using Principal Component Analysis. Laboratory examination was performed to evaluate the quality of attempts to extract content from the examined linguistic features.

RESULTS

The PUBMED search yielded a total of 14,420 abstracts (3,190,219 words). The range of findings in laboratory experimentation were coherent with the variability of the results described in the analyzed body of literature. Increased concurrence of chemokine identifiers together with cancer related terms was found at the abstract and sentence level, whereas complexity of sentences remained fairly stable.

CONCLUSIONS

The findings of the present study indicate that concurrent references to chemokines and cancer increased over time whereas text complexity remained stable.

LPS-induced CXCR4-dependent migratory properties and a mesenchymal-like phenotype of colorectal cancer cells

Colorectal cancer (CRC) is the most commonly diagnosed cancer worldwide, and over 50% of patients will develop hepatic metastasis during the course of their disease. CXCR4 and its ligand, stromal cell-derived factor 1α (SDF-1α)/chemokine (C-X-C motif) ligand 12 (CXCL12) have been revealed as regulatory molecules involved in the spreading and progression of a variety of tumors. Here we have shown that lipopolysaccharides (LPS) promoted the migratory capacity of colon cancer cells in vivo and in vitro, which correlated with the activation of SDF-1α/CXCR4 axis and epithelial-mesenchymal transition (EMT) occurrence. Additionally, we found that LPS-induced CXCR4 expression and EMT through NF-κB signaling pathway activation. And inhibition of NF-κB pathway, which recovered the epithelial phenotype and attenuated CXCR4 expression, inhibited cell migratory capacity. Clinically, high levels of CXCR4 always correlated with metastasis and poor prognosis of CRC patients. In conclusion, LPS participate in the whole process of hepatic metastasis of CRC, not only causing liver damage resulting in the production of SDF-1α, but also enhancing the invasive potential of CRC cells by promoting CXCR4 expression and EMT occurrence, which would contribute to the enhancement of cell migration and invasion.

The role of chemoattractant receptors in shaping the tumor microenvironment

Chemoattractant receptors are a family of seven transmembrane G protein coupled receptors (GPCRs) initially found to mediate the chemotaxis and activation of immune cells. During the past decades, the functions of these GPCRs have been discovered to not only regulate leukocyte trafficking and promote immune responses, but also play important roles in homeostasis, development, angiogenesis, and tumor progression. Accumulating evidence indicates that chemoattractant GPCRs and their ligands promote the progression of malignant tumors based on their capacity to orchestrate the infiltration of the tumor microenvironment by immune cells, endothelial cells, fibroblasts, and mesenchymal cells. This facilitates the interaction of tumor cells with host cells, tumor cells with tumor cells, and host cells with host cells to provide a basis for the expansion of established tumors and development of distant metastasis. In addition, many malignant tumors of the nonhematopoietic origin express multiple chemoattractant GPCRs that increase the invasiveness and metastasis of tumor cells. Therefore, GPCRs and their ligands constitute targets for the development of novel antitumor therapeutics.

CCR6/CCL20 chemokine expression profile in distinct colorectal malignancies

Originally, chemokines and their G-protein-coupled receptors were described to regulate multiple physiological functions, particularly tissue architecture and compartment-specific migration of white blood cells. Now, it is established that the chemokine/chemokine receptor system is also used by cancer cells for migration and metastatic spread. Here, we examined the relative levels of CC-chemokine CCL20 and its corresponding receptor CCR6 in resection specimens from patients with different malignant and non-malignant colorectal diseases as well as in colorectal liver metastases (CRLM). CCL20/CCR6 mRNA and protein expression profiles were assessed by quantitative real-time PCR (qRT-PCR), enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) in resection specimens from patients with ulcerative colitis (UC, n = 15), colorectal adenoma (CRA, n = 15), colorectal adenocarcinoma (CRC, n = 61) and colorectal liver metastases (CRLM, n = 16). Corresponding non-diseased tissues served as control. In contrast to UC tissues, the CCL20/CCR6 system showed a distinct upregulation in CRA, CRC and CRLM related to corresponding non-affected tissues (P < 0.05, respectively). Furthermore, CRA, CRC and CRLM tissue samples displayed significantly higher protein amounts of CCL20 in comparison with UC specimens (P < 0.05, respectively). Our results strongly suggest an association between CCL20/CCR6 expression and the induction of CRA, CRC and the development of CRLM. Therefore, CCL20 and CCR6 may provide potential targets for novel treatment strategies of CRC.

Activated tumor-infiltrating CD4+ regulatory T cells restrain antitumor immunity in patients with primary or metastatic liver cancer

The mechanisms that enable liver cancer to escape elimination by the immune system remain unclear, but their elucidation may provide novel therapeutic interventions. We investigated the influence of tumor-infiltrating regulatory T cells on tumor-specific T cell responses in patients with liver cancer, using ex vivo isolated cells from individuals with hepatocellular carcinoma (HCC) or liver metastases from colorectal cancer (LM-CRC). Here we report that in both HCC and LM-CRC, CD4+CD25+Foxp3+ regulatory T cells (Tregs) accumulate in the tumor milieu and are potent suppressors of autologous tumor-specific T cell responses. Especially in LM-CRC, where Treg accumulation is more prominent, there is good evidence for local proliferation of Tregs at the cancer site. We show that tumor Tregs up-regulate the expression of glucocorticoid-induced tumor necrosis factor receptor (GITR) compared with Tregs in tumor-free liver tissue and blood. Importantly, treatment with soluble GITR ligand (GITRL) induces a decrease in the suppression mediated by the activated tumor-infiltrating Tregs and restores the proliferative capacity and cytokine production of CD4+CD25- T cells.

CONCLUSION

Our results show that tumor-associated Tregs are critical for immune evasion in liver cancer, and we propose that GITRL constitutes a rational treatment for this disease.

Expression of haematogenous and lymphogenous chemokine receptors and their ligands on uveal melanoma in association with liver metastasis

PURPOSE

Chemokine receptors and their ligands are involved in a number of cell processes, including normal cell trafficking as well as metastasis in cancer. During metastasis, they are thought to play a role in determining cancer cell distribution and target organs. The aim of this study was to examine the expression of the chemokine receptors CXCR4, CCR7 and CCR10 as well as their respective chemokine ligands (CXCL12, CCL19, CCL27) in human uveal melanomas.

METHODS

Seventy formalin-fixed paraffin-embedded uveal melanoma specimens from patients treated in 1996-1997 were examined using immunohistochemistry and evaluated using an immune reactive score (IRS).

RESULTS

The chemokine receptors CXCR4, CCR7 and CCR10 were primarily expressed in the cytoplasm of uveal melanoma cells, with CXCR4 (average IRS 8.2) and CCR7 (average IRS 5.7) showing the strongest expression, respectively. The chemokine ligand CCL19 demonstrated a moderate expression (average IRS 5.3), whereas the expression of receptor CCR10 (average IRS of 3.4), ligand CCL27 (average IRS 2.5) and ligand CXCL12 (average IRS 0.6) by uveal melanoma cells was low. A significant association between liver metastases and chemokine expression was found for CCR7 expression (p = 0.037) only. Comparison of liver metastasis and choroid uveal melanoma (35.3%, n = 12 of 34) versus ciliary body involvement (72.7%, n = 8 of 11) was significant (p = 0.030).

CONCLUSION

Chemokine receptors are more strongly expressed on uveal melanoma cells than their ligands. Our results show new aspects of the metastatic process in uveal melanoma.

Overexpression of CCL20 and its receptor CCR6 predicts poor clinical prognosis in human gliomas

Recent studies have demonstrated that the chemokine CCL20 and its receptor CCR6 may be involved in tumorigenesis, tumor progression and metastatic spread of various human malignancies. The aim of this study was to investigate the clinicopathological significance and prognostic value of CCL20 and CCR6 expression in human malignant glioma. CCL20 and CCR6 expression in human gliomas and nonneoplastic brain tissues was measured by immunohistochemistry. The association of CCL20 and CCR6 expression with clinicopathological factors or prognosis in glioma patients was statistically analyzed. The expression levels of CCL20 and CCR6 proteins were both up-regulated in glioma tissues. There was a significantly positive correlation between the expression of the two markers (r = 0.88; P < 0.001). In addition, the overexpressions of CCL20 and CCR6 were both detected in high-grade glioma tissues compared with those in low-grade tissues and increased with ascending tumor World Health Organization (WHO) grades (P = 0.006 and 0.008, respectively). The increased expressions of CCL20 and CCR6 proteins were also significantly correlated with low Karnofsky performance score (both P = 0.01). Moreover, univariate analysis found that CCL20 expression (P = 0.002), CCR6 expression (P = 0.002) and CCL20/CCR6 co-expression (P < 0.001) were all significantly associated with poor prognosis. In particular, glioma patients with CCL20/CCR6 co-expression have the shortest overall survival. Multivariate analysis further identified the expression levels of CCL20 and CCR6 to be independent prognostic factors. Our data suggest for the first time that CCL20 and CCR6 might play an important role in the regulation of aggressiveness in human gliomas. The up-regulation of CCL20 and CCR6 might be closely associated with poor clinical outcome of patients with gliomas.

CC chemokine ligand 7 expression in liver metastasis of colorectal cancer

The main cause of death for colorectal cancer (CRC) patients is the development of metastatic lesions at sites distant from the primary tumor. Therefore, it is important to find biomarkers that are related to the metastasis and to study the possible mechanisms. Recent data have shown that soluble attractant molecules called chemokines support the metastasis of certain cancers to certain organs. To identify molecular regulators that are differentially expressed in liver metastasis of CRC, PCR array analysis was performed and CC chemokine ligand 7 (CCL7) showed remarkable overexpression in liver metastatic tumor tissues. To validate the results of the PCR array, 30 patients with primary CRC and liver metastases were selected. Immunohistochemistry and real-time PCR analysis showed that CCL7 was expressed in normal colonic epithelium and the expression was higher in liver metastases compared to primary CRC (p<0.001). Real-time PCR showed that the expression of CCR1, CCR2 and CCR3 was also higher in liver metastases compared to primary CRC (p=0.001, p=0.033 and p<0.001, respectively). In conclusion, correlation of CCL7 overexpression and its receptor expression with colon cancer liver metastasis suggests that CCL7 as a novel target in liver metastasis of CRC may be of potential clinical value for the prevention of hepatic recurrences.

High expression of CCL20 is associated with poor prognosis in patients with hepatocellular carcinoma after curative resection

INTRODUCTION

Chemokine ligand 20 (CCL20) plays an important role in the carcinogenesis, invasion, and progression of malignancies. This study aimed to investigate the prognostic significance of CCL20 in patients with hepatocellular carcinoma (HCC) after curative resection.

METHODS

Expression of CCL20 was evaluated by immunohistochemistry in tumor tissue from 125 patients who underwent curative resection of HCC. The relationship between CCL20 expression and clinicopathologic features was analyzed. Univariate and multivariate analyses were performed to evaluate its predictive value for tumor recurrence and survival of HCC patients.

RESULTS

CCL20 expression was verified in all tumor specimens. CCL20 expression was associated with tumor size (P = 0.002), tumor number (P = 0.031), vascular invasion (P = 0.003), tumor differentiation (P = 0.024), and tumor recurrence (P < 0.001). Patients with high CCL20 expression had poorer recurrence-free survival and overall survival (both P < 0.001) than those with low CCL20 expression. Multivariate analysis showed CCL20 expression was an independent predictor of tumor recurrence (Hazard ratio 3.934, P = 0.002), recurrence-free survival (Hazard ratio 2.573, P = 0.001), and overall survival (Hazard ratio 2.930, P = 0.001).

CONCLUSION

CCL20 expression was associated with tumor recurrence and survival of HCC patients. It may be used to predict prognosis of patients with HCC and may be a new target of postoperative adjuvant therapy.

CXC receptor-4 mRNA silencing abrogates CXCL12-induced migration of colorectal cancer cells

BACKGROUND

Interactions between CXCR4 and its ligand CXCL12 have been shown to be involved in cancer progression in colorectal cancer (CRC). We performed a comparative CXCL12/CXCR4 expression analysis and assessed the effect of external CXCL12 stimulation on migration of CRC cells without and with CXCR4 inhibition.

METHODS

Expression of CXCL12/CXCR4 was assessed by quantitative real-time PCR, ELISA and immunohistochemistry in resection specimens of 50 CRC patients as well as in the corresponding normal tissues and in three human CRC cell lines with different metastatic potential (Caco-2, SW480 and HT-29). Migration assays were performed after stimulation with CXCL12 and CXCR4 was inhibited by siRNA and neutralizing antibodies.

RESULTS

In CRC tissues CXCL12 was significantly down-regulated and CXCR4 was significantly up-regulated compared to the corresponding normal tissues. In cell lines CXCR4 was predominantly expressed in SW480 and less pronounced in HT-29 cells. CXCL12 was only detectable in Caco-2 cells. CXCL12 stimulation had no impact on Caco-2 cells but significantly increased migration of CXCR4 bearing SW480 and HT-29 cells. This effect was significantly abrogated by neutralizing anti-CXCR4 antibody as well as by CXCR4 siRNAs (P < 0.05).

CONCLUSIONS

CXCR4 expression was up-regulated in CRC and CXCL12 stimulation increased migration in CXCR4 bearing cell lines. Migration was inhibited by both neutralizing CXCR4 antibodies and CXCR4 siRNAs. Thus, the expression and functionality of CXCR4 might be associated with the metastatic potential of CRC cells and CXCL12/CXCR4 interactions might therefore constitute a promising target for specific treatment interventions.

Screen and analysis of key disease genes for precancerous lesions of oral buccal mucosa induced by DMBA in golden hamsters

7,12-Dimethylbenz(a)-anthracene (DMBA)-induced oral buccal mucosa squamous cell carcinoma in Syrian golden hamsters was used to establish precancerous lesions. Agilent rat whole-genome microarray and biological information analysis were used to screen for genes related to key diseases during the transformation of normal buccal mucosa to precancerous lesions in golden hamsters. DMBA acetone solution (0.5%) was used to establish a model of precancerous lesions in oral buccal mucosa in golden hamsters. The results showed that a total of 1331 genes were differentially expressed, including 1278 known, 53 unknown, 747 up-regulated and 584 down-regulated genes. Analysis revealed a total of 14 gene interaction pathways that significantly associated with the 1278 known differentially expressed genes (P<0.05). In conclusion, the occurrence of precancerous lesions in the oral buccal mucosa of golden hamsters was caused by a number of genetic changes that resulted in changes to their respective pathways. Key candidate genes for the formation of precancerous lesions in oral buccal mucosa included Cyp2b13, Orc1L, casp8, CCL5, CXCL12, CCL20, Serping1, P518/Qrfp, F5, TFPI, Vcam1, Fn1, Angpt2, Lcp2, Cxadr, Lyn, Hck, Btk, RGD1564385/fes, Vav1 and IL5ra.

Expression of the chemokine receptor CCR6 correlates with a favorable prognosis in patients with adenocarcinoma of the lung

The relation between CCR6 expression and the clinicopathological characteristics of lung cancer and patient prognosis is not well understood and remains controversial. We, therefore, investigated the relationship between CCR6 expression and prognosis in patients with adenocarcinoma of the lung. We used semiquantitative real-time reverse transcription polymerase chain reaction to assess the expression of CCR6 mRNA in tumor samples from 84 patients with adenocarcinoma of the lung. We then correlated the levels of CCR6 mRNA with known clinicopathological features. The 5-year disease-free survival rate among patients expressing higher levels of CCR6 mRNA was significantly better than among those expressing lower levels (P = 0.009 by log-rank test). Multivariate Cox proportional hazard analyses revealed, being male [hazard ratio, 3.94; 95% confidence interval (CI), 1.58 to 10.36; P = 0.003], tumor size >30 mm (hazard ratio, 2.46; 95% CI, 1.08 to 5.73; P = 0.030), nodal metastasis (hazard ratio, 7.66; 95% CI, 2.62 to 23.3; P = 0.0002), and CCR6 (hazard ratio, 0.34; 95% CI, 0.11 to 0.93; P = 0.034) to be independent factors affecting the 5-year disease-free survival rate. Greater expression of CCR6 by tumor cells is an independent predictor of a better prognosis in patients with adenocarcinoma of the lung.

Polybrominated diphenyl ethers and arylhydrocarbon receptor agonists: Different toxicity and target gene expression

Polybrominated diphenyl ethers (PBDEs) accumulate in the environment and in humans. PBDEs are developmental neurotoxicants, disturb the endocrine system and induce tumors in rodents. However, underlying mechanisms of PBDE toxicity are still insufficiently understood. Some reports demonstrated activation but also inhibition of the aryl hydrocarbon receptor (AhR) by PBDEs based on expression of its target gene cyp1A1. In the present study, we used different PBDE congeners (BDE47, 99, 153 and 209) and analyzed their effects on AhR signaling in various cell lines and zebrafish embryos. Furthermore, we performed microarray experiments in rat hepatoma cells to compare changes in gene expression induced by either BDE47 or the AhR agonist 2,3,7,8-tetrabromo-dibenzofuran (TBDF). PBDEs did not activate but rather inhibited AhR signaling and specifically induced malformations in zebrafish embryos, which differ from those provoked by AhR agonists. Furthermore, BDE47 and TBDF differentially regulated global gene expression in hepatoma cells. Hence, PBDEs and AhR agonists trigger different toxicity and target gene expression. Several novel target genes of BDE47 and TBDF were identified and verified by RT-PCR. TBDF induced expression of the transcriptional regulators Sim2 and RevErbbeta whereas BDE47 specifically deregulated expression of two subunits of the cytochrome c oxidase complex, cox6a2 and cox4i2, which might be linked to its toxicity.

Chemokines and hepatocellular carcinoma

Chemokines play a paramount role in tumor progression. In hepatocellular carcinoma (HCC) progression, chemokines and their receptors play an intricate role. Currently, chemokines and their receptors such as the CXCL12-CXCR4 axis, CX3CL1-CX3CR1 axis and the CCL20-CCR6 axis have received much research attention. Although a large number of studies show that these axes are strongly associated with HCC, the exact mechanism by which these axes promote the growth and progression of HCC remains unknown. In this paper, several chemokines and their receptor interactions in HCC progression, growth and metastasis and immune response to HCC are reviewed.

Deregulation of HIF1-alpha and hypoxia-regulated pathways in hepatocellular carcinoma and corresponding non-malignant liver tissue--influence of a modulated host stroma on the prognosis of HCC

PURPOSE

The aim of this study was to elucidate the role of HIF1A expression in hepatocellular carcinoma (HCC) and the corresponding non-malignant liver tissue and to correlate it with the clinical outcome of HCC patients after curative liver resection.

METHODS

HIF1A expression was determined by quantitative RT-PCR in HCC and corresponding non-malignant liver tissue of 53 patients surgically treated for HCC. High-density gene expression analysis and pathway analysis was performed on a selected subset of patients with high and low HIF1A expression in the non-malignant liver tissue.

RESULTS

HIF1A over-expression in the apparently non-malignant liver tissue was a predictor of tumor recurrence and survival. The estimated 1-year and 5-year disease-free survival was significantly better in patients with low HIF1A expression in the non-malignant liver tissue when compared to those patients with high HIF1 expression (88.9% vs. 67.9% and 61.0% vs. 22.6%, respectively, p = 0.008). Based on molecular pathway analysis utilizing high-density gene-expression profiling, HIF1A related molecular networks were identified that contained genes involved in cell migration, cell homing, and cell-cell interaction.

CONCLUSION

Our study identified a potential novel mechanism contributing to prognosis of HCC. The deregulation of HIF1A and its related pathways in the apparently non-malignant liver tissue provides for a modulated environment that potentially enhances or allows for HCC recurrence after curative resection.

Gene expression profile analysis of human hepatocellular carcinoma using SAGE and LongSAGE

Background

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and the second cancer killer in China. The initiation and malignant transformation of cancer result from accumulation of genetic changes in the sequences or expression level of cancer-related genes. It is of particular importance to determine gene expression profiles of cancers on a global scale. SAGE and LongSAGE have been developed for this purpose.

Methods

We performed SAGE in normal liver and HCC samples as well as the liver cancer cell line HepG2. Meanwhile, the same HCC sample was simultaneously analyzed using LongSAGE. Computational analysis was carried out to identify differentially expressed genes between normal liver and HCC which were further validated by real-time quantitative RT-PCR.

Results

Approximately 50,000 tags were sequenced for each of the four libraries. Analysis of the technical replicates of HCC indicated that excluding the low abundance tags, the reproducibility of SAGE data is high (R = 0.97). Compared with the gene expression profile of normal liver, 224 genes related to biosynthesis, cell proliferation, signal transduction, cellular metabolism and transport were identified to be differentially expressed in HCC. Overexpression of some transcripts selected from SAGE data was validated by real-time quantitative RT-PCR. Interestingly, sarcoglycan-ε (SGCE) and paternally expressed gene (PEG10) which is a pair of close neighboring genes on chromosome 7q21, showed similar enhanced expression patterns in HCC, implicating that a common mechanism of deregulation may be shared by these two genes.

Conclusion

Our study depicted the expression profile of HCC on a genome-wide scale without the restriction of annotation databases, and provided novel candidate genes that might be related to HCC.

Differential CXC receptor expression in colorectal carcinomas

In this study, we aimed to assess the expression profile of chemokine receptors CXCR1-4 in inflammatory and malignant colorectal diseases and corresponding hepatic metastases of synchronous and metachronous origin to elucidate their role in colorectal cancer (CRC) progression and metastasis. Chemokine receptor expression was assessed by quantitative real-time PCR, immunohistochemistry (IHC) and Western blot analysis in resection specimens from patients with ulcerative colitis (UC, n = 25), colorectal adenomas (CRA, n = 8), different stages of CRC (n = 48) as well as colorectal liver metastases (CRLM) along with their corresponding primary colorectal tumours (n = 16). While none of the chemokine receptors were significantly upregulated or downregulated in UC or CRA tissues, CXC receptors 1, 2 and 4 demonstrated a significant increase in expression in all tumour stages of CRC specimens with CXCR4 correlating with tumour grading (P < 0.05). On the other hand, CXCR3 showed no significant upregulation in either tumour stage, but significant overexpression in CRLM. While CXCR4 demonstrated significant upregulation in both tumour entities, IHC analysis revealed that the predominate cell type expressing CXCR4 in CRC is represented by tumour cells, whereas in CRLM the majority of positive CXCR4 signals is due to hepatocytes along the tumour invasion front. In conclusion, our findings show a very differential expression pattern of the four receptors in colorectal carcinomas and their corresponding liver metastases with prominent expression profiles that indicate a potential role in the pathogenesis of CRC.

Expression profiling of angiogenic genes for the characterisation of colorectal carcinoma

The development of new blood and lymphatic vessels is a crucial event for cancer growth, metastatic spread and relapse after therapy. In this work, the expression levels of chemokines, angiogenic and angiostatic factors and their receptors were determined in paired mucosal and tumour samples of patients with colorectal carcinoma and correlated with clinical and histological parameters by advanced multivariate analyses. The most important predictors to discriminate between tumour and paired normal mucosa turned out to be the levels of expression of plexin-A1 and stromal cell-derived factor 1 (SDF-1), the former overexpressed and the latter downregulated in tumours. The levels of osteopontin and Tie-2 transcripts discriminated between the presence and absence of lymph node infiltration, the former overexpressed in the presence of infiltration whilst the latter providing a protective role. These results add support to the notion that the expression levels of selected genes involved in new blood and lymphatic vessel formation represent trustable biomarkers of tumour development and invasion and contribute to the identification of novel molecular classifiers for colorectal carcinoma.

G-protein coupled chemoattractant receptors and cancer

Chemoattractant receptors are a group of seven transmembrane, G protein coupled receptors (GPCRs). They were initially identified mainly on leukocytes to mediate cell migration in response to pathogen or host-derived chemotactic factors. During the past decade, chemoattractant GPCRs have been discovered not only to mediate leukocyte chemotaxis thus promoting innate and adaptive host immune responses, but also to play essential roles in development, homeostasis, HIV infection, angiogenesis and wound healing. A growing body of evidence further indicates that chemoattractant GPCRs contribute to tumor growth, invasion, angiogenesis/angiostasis and metastasis. The diverse properties of GPCRs in the progression of malignant tumors have attracted intense interest in their potential as novel anti-tumor pharmacological targets.

Chemokines and cancer: migration, intracellular signalling and intercellular communication in the microenvironment

Inappropriate chemokine/receptor expression or regulation is linked to many diseases, especially those characterized by an excessive cellular infiltrate, such as rheumatoid arthritis and other inflammatory disorders. There is now overwhelming evidence that chemokines are also involved in the progression of cancer, where they function in several capacities. First, specific chemokine-receptor pairs are involved in tumour metastasis. This is not surprising, in view of their role as chemoattractants in cell migration. Secondly, chemokines help to shape the tumour microenvironment, often in favour of tumour growth and metastasis, by recruitment of leucocytes and activation of pro-inflammatory mediators. Emerging evidence suggests that chemokine receptor signalling also contributes to survival and proliferation, which may be particularly important for metastasized cells to adapt to foreign environments. However, there is considerable diversity and complexity in the chemokine network, both at the chemokine/receptor level and in the downstream signalling pathways they couple into, which may be key to a better understanding of how and why particular chemokines contribute to cancer growth and metastasis. Further investigation into these areas may identify targets that, if inhibited, could render cancer cells more susceptible to chemotherapy.

Effect of specific suppression of chemokine receptor CXCR4 by short interference RNA on the invasion capability and proliferation of colorectal cancer cells

AIM: To study the inhibitory effect of chemokine receptor CXCR4 short interference RNA (siRNA) on the invasion capability and proliferation of colorectal cancer cell line SW480.

METHODS: SiRNA specifically targeting CXC chemokine receptor CXCR4 was designed in vitro using T7 RNA polymerase. Colorectal cancer SW480 cells were cultured under standard condition and the siRNA was transfected into SW480 cells with Lipofectamine 2000. Negative control and mock control were used at the same time. The levels of CXCR4 mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting 48 h after transfection respectively. The changes of invasion capability and MT1-MMP protein in SW480 cells were evaluated using Boyden Chamber invasion assay and Western blotting respectively. The cell cycle distribution and proliferation status were detected by flow cytometry and MTT assay respectively.

RESULTS: Forty-eight hours after transfection with CXCR4 siRNA, in comparison with those in negative and mock control group, the levels of CXCR4 mRNA (51.53% ± 6.1% vs 78.4% ± 3.3%, P < 0.01; 51.53% ± 6.1% vs 87.4% ± 5.3%, P < 0.01) and protein (47.3% ± 3.7% vs 107.2% ± 3.6%, P < 0.01; 47.3% ± 3.7% vs 114.7% ± 4.8%, P < 0.01) decreased significantly (47.3% ± 3.7% vs 107.2% ± 3.6%, P < 0.01; 47.3% ± 3.7% vs 114.7% ± 4.8%, P < 0.01); the invasion capability (26.5% ± 6.1% vs 73.7% ± 3.4%, P < 0.01; 26.5% ± 6.1% vs 64.5% ± 5.7%, P < 0.01) and the MT1-MMP protein expression (43.8% ± 2.5% vs 64.4% ± 4.4%, P < 0.01; 43.8% ± 2.5% vs 67.0% ± 2.9%, P < 0.01) in SW480 cells decreased significantly, but the cell cycle distribution didn't change remarkably. At the absence of SDF-1, cell proliferation status was similar to that in control and mock control group. After stimulation by SDF-1, the proliferation of SW480 cells increased in all the groups, but it was much less active in the CXCR4 siRNA group than in the other two control groups.

CONCLUSION: CXCR4 siRNA can inhibit the expression of CXCR4 and decrease the invasion capability and proliferation of SW480 cells.