Inflammation-induced hepatocellular carcinoma is dependent on CCR5 in mice

Role of chemokine pathways in hepatobiliary cancer

Persistent hepatic inflammation resulting from hepatitis B or C virus infections (HBV or HCV, respectively), obesity-associated non-alcoholic steatohepatitis (NASH) or alcohol abuse is a hallmark feature of chronic liver diseases and appears to be an essential prerequisite of hepatocarcinogenesis. The inflammatory processes in the liver are regulated by various chemokines, which orchestrate the interaction between parenchymal liver cells, Kupffer cells (resident macrophages), hepatic stellate cells (HSC), endothelial cells, and infiltrating immune cells. In consequence, these cellular interactions result in the re-modeling of the hepatic microenvironment toward a pro-inflammatory, pro-fibrotic, pro-angiogenic and thus pre-neoplastic milieu. Once developed, liver neoplasms provoke pro- and anti-tumor immune responses that are also critically regulated through differential activation of chemokine pathways. With respect to hepatobiliary cancers, including hepatocellular carcinoma (HCC), gallbladder cancer and cholangiocellular carcinoma (cholangiocarcinoma), together belonging to the highest causes of cancer-related deaths worldwide, this review article will give an overview of chemokine pathways involved in both the establishment of a pro-tumorigenic microenvironment as well as the development and progression of hepatobiliary cancer. Pharmaceutical targeting of chemokine pathways is a promising approach to treat or even prevent hepatobiliary cancer.

Chemokines and their receptors play important roles in the development of hepatocellular carcinoma

The chemokine system consists of four different subclasses with over 50 chemokines and 19 receptors. Their functions in the immune system have been well elucidated and research during the last decades unveils their new roles in hepatocellular carcinoma (HCC). The chemokines and their receptors in the microenvironment influence the development of HCC by several aspects including: inflammation, effects on immune cells, angiogenesis, and direct effects on HCC cells. Regarding these aspects, pre-clinical research by targeting the chemokine system has yielded promising data, and these findings bring us new clues in the chemokine-based therapies for HCC.

Chronic liver inflammation modifies DNA methylation at the precancerous stage of murine hepatocarcinogenesis

Chronic liver inflammation precedes the majority of hepatocellular carcinomas (HCC). Here, we explore the connection between chronic inflammation and DNA methylation in the liver at the late precancerous stages of HCC development in Mdr2(-/-) (Mdr2/Abcb4-knockout) mice, a model of inflammation-mediated HCC. Using methylated DNA immunoprecipitation followed by hybridization with "CpG islands" (CGIs) microarrays, we found specific CGIs in 76 genes which were hypermethylated in the Mdr2(-/-) liver compared to age-matched healthy controls. The observed hypermethylation resulted mainly from an age-dependent decrease of methylation of the specific CGIs in control livers with no decrease in mutant mice. Chronic inflammation did not change global levels of DNA methylation in Mdr2(-/-) liver, but caused a 2-fold decrease of the global 5-hydroxymethylcytosine level in mutants compared to controls. Liver cell fractionation revealed, that the relative hypermethylation of specific CGIs in Mdr2(-/-) livers affected either hepatocyte, or non-hepatocyte, or both fractions without a correlation between changes of gene methylation and expression. Our findings demonstrate that chronic liver inflammation causes hypermethylation of specific CGIs, which may affect both hepatocytes and non-hepatocyte liver cells. These changes may serve as useful markers of an increased regenerative activity and of a late precancerous stage in the chronically inflamed liver.

Effectiveness of localized ultrasound-targeted microbubble destruction with doxorubicin liposomes in H22 mouse hepatocellular carcinoma model

OBJECTIVE

In order to increase local drug concentration and reduce systemic side effects of liver cancer chemotherapy, it is desirable to develop novel non-invasive technologies for drug targeting, such as ultrasound-targeted microbubble destruction (UTMD).

METHODS

H22 hepatocellular carcinoma (HCC) xenograft transplantation model was generated in UTMD study. BALB/c mice were randomly divided into six groups: doxorubicin HCl liposomal injection (DOX), DOX + US, UTMD, DOX + UTMD, H22 liver tumor control (CH control) and blank control group. The therapeutic schedule started on day 4 after tumor inoculation.

RESULTS

Average survival time of the animal model was approximately 18 d. The UTMD therapy parameters were optimized in the H22 mouse model to be: microbubble (MB) diameter, 2.30 ± 0.25 μm; MB density, 4.0 × 10(9) bubbles/ml; treatment dose, 0.2 ml per 20 g mouse body weight; sonication frequency, 1.3 MHz; and sonication power, 2.06 W/cm(2). Mice treated with DOX + UTMD had the smallest tumor volume and weight (p < 0.001), and the highest tumor inhibition rate (p < 0.01), intratumoral DOX concentration (p < 0.001) and survival rate among all tumor-burden groups (p < 0.001). Cell viability in different treatment groups was also assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

CONCLUSION

An improved antitumor effect was observed with the combination therapy of DOX and UTMD, as compared with treatment with DOX, DOX + US or UTMD, which implicates a novel approach for HCC treatment.

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.

HPV associated tumor cells control tumor microenvironment and leukocytosis in experimental models

Human papillomavirus (HPV) is the main etiological factor for cervical cancer development. HPV is also associated with other anogenital and oropharyngeal tumors. HPV associated tumors are frequent and constitute a public health problem, mainly in developing countries. Therapy against such tumors is usually excisional, causing iatrogenic morbidity. Therefore, development of strategies for new therapies is desirable. The tumor microenvironment is essential for tumor growth, where inflammation is an important component, displaying a central role in tumor progression. Inflammation may be a causal agent, suppressor of anti-tumor T cell responses, or may have a role in angiogenesis, drug resistance, and metastasis. The aim of this work was to investigate the role of HPV transformed cells in the tumor microenvironment and tumor effects on myeloid populations in lymphoid organs in the host. We used experimental models, where we injected cervical cancer derived cell lines in immunodeficient mice, comparing HPV positive, SiHa, and HeLa cells (HPV 16 and HPV18, respectively), with HPV negative cell line, C33A. Our data shows that HPV positive cell lines were more efficient than the HPV negative cell line in leukocyte recruitment to the tumor microenvironment and increase in myeloid cell proliferation in the bone marrow and spleen. We also observed that HPV positive cells lines expressed significantly higher levels of IL-6 and IL-8, while C33A expressed significantly higher levels of IL-16 and IL-17. Finally, in spite of cytokine secretion by tumor cells, leukocytes infiltrating SiHa and HeLa tumors displayed almost negligible STAT3 and no NFκB phosphorylation. Only the inflammatory infiltrate of C33A tumors had NFκB and STAT3 activated isoforms. Our results indicate that, although from the same anatomical site, the uterine cervix, these cell lines display important differences regarding inflammation. These results are important for the design of immunotherapies against cervical cancer, and possibly against HPV associated tumors in other anatomical sites.

CCL5 secreted from bone marrow stromal cells stimulates the migration and invasion of Huh7 hepatocellular carcinoma cells via the PI3K-Akt pathway

Bone metastases from hepatocellular carcinoma (HCC) seem to be increasing. Previous studies showed that soluble factors secreted by host cells and direct cell-to-cell interactions contributed to the preferential metastasis and growth of cancer cells in bone, while the underlying mechanism(s) of the metastasis of HCC in the bone are poorly understood. Here, we determined the effect of HS-5 cells on Huh7 cell proliferation, and investigated the role of CCL5 from HS-5 cells on the development of Huh7 cells. In addition, the underlying mechanisms on the influence in Huh7 cells were investigated. Our results showed that HS-5 cells could promote the proliferation, migration and invasion of Huh7 cells, and inhibited apoptosis. CCL5 downregulation was able to inhibit the effects of HS-5 cells on Huh7 cell migration and invasion via the PI3K-Akt signaling pathway and reduce MMP-2 expression. Therefore, these findings suggest that CCL5 secreted from MSCs can promote the migration and invasion of Huh7 cells and could be an important factor in HCC related to occurrence of bone metastases.

Prognostic significance of the neutrophil-to-lymphocyte ratio in primary liver cancer: a meta-analysis

The neutrophil-to-lymphocyte ratio (NLR) is a useful biomarker that reflects systemic inflammation responses. However, the prognostic value of the NLR in patients with primary liver cancer (PLC) remains controversial. We performed a meta-analysis of 26 studies (comprising 4,461 patients) to evaluate the association between the pre-treatment NLR and clinical outcomes of overall survival (OS) and disease-free survival (DFS) in patients with PLC. The correlation between NLR and tumor characteristics or other inflammation-related parameters was also assessed. Data were synthesized using the random-effects model of DerSimonian and Laird, and the hazard ratio (HR) or odds ratio (OR) with 95% confidence interval (CI) was used to estimate effect size. Our analysis indicated that a high NLR predicted poor OS (HR, 2.102; 95% CI: 1.741-2.538) and DFS (HR, 2.474; 95% CI: 1.855-3.300) for PLC. A high NLR was associated with the presence of tumor vascular invasion (OR: 1.889, 95% CI: 1.487-2.400; p<0.001) and an elevated alpha-fetoprotein level (OR: 1.536; 95% CI: 1.152-2.048; p = 0.003). Thus, we conclude that a high NLR indicates a poor prognosis for patients with PLC and may also be predictive for PLC invasion and metastasis. Subgroup analysis suggested that the predictive role of NLR in cholangiocarcinoma is limited, and a further large study to confirm these findings is warranted.

Maraviroc, a CCR5 antagonist, ameliorates the development of hepatic steatosis in a mouse model of non-alcoholic fatty liver disease (NAFLD)

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the general population. The NAFLD spectrum ranges from simple steatosis to cirrhosis. The chemokine CCL5/RANTES plays an important role in the progression of hepatic inflammation and fibrosis. The objective of this study was to examine the effects of maraviroc, a CCR5 antagonist, on liver pathology in a NAFLD mouse model.

METHODS

A total of 32 male C57BL/6 mice were randomly assigned to one of four groups: (i) control group (chow diet plus tap water); (ii) maraviroc group (chow diet plus maraviroc in drinking water); (iii) high-fat diet (HFD) group (HFD plus tap water); and (iv) maraviroc/HFD group (HFD plus maraviroc). All mice were sacrificed 16 weeks after the beginning of the experiment. Biochemical analyses and liver examinations were performed.

RESULTS

Mice in the HFD group showed a tendency towards increased body mass gain and liver damage compared with the maraviroc/HFD group. Moreover, liver weight in the HFD group was significantly higher than in the maraviroc/HFD group. Hepatic triglyceride concentration in the maraviroc/HFD group was significantly lower than in the HFD group. Interestingly, the maraviroc/HFD group exhibited a lower degree of steatosis. Furthermore, hepatic CCL5/RANTES expression was significantly lower in the maraviroc/HFD group than in the HFD group. Overall, no differences were observed between the control group and the maraviroc group.

CONCLUSIONS

Maraviroc ameliorates hepatic steatosis in an experimental model of NAFLD.

The role of chemokines in hepatitis C virus-mediated liver disease

The hepatitis C virus (HCV) is a global health problem affecting more than 170 million people. A chronic HCV infection is associated with liver fibrosis, liver cirrhosis and hepatocellular carcinoma. To enable viral persistence, HCV has developed mechanisms to modulate both innate and adaptive immunity. The recruitment of antiviral immune cells in the liver is mainly dependent on the release of specific chemokines. Thus, the modulation of their expression could represent an efficient viral escape mechanism to hamper specific immune cell migration to the liver during the acute phase of the infection. HCV-mediated changes in hepatic immune cell chemotaxis during the chronic phase of the infection are significantly affecting antiviral immunity and tissue damage and thus influence survival of both the host and the virus. This review summarizes our current understanding of the HCV-mediated modulation of chemokine expression and of its impact on the development of liver disease. A profound knowledge of the strategies used by HCV to interfere with the host's immune response and the pro-fibrotic and pro-carcinogenic activities of HCV is essential to be able to design effective immunotherapies against HCV and HCV-mediated liver diseases.

Effect of occult hepatitis B virus infection on the early-onset of hepatocellular carcinoma in patients with hepatitis C virus infection

Although overt hepatitis B virus (HBV) infection promotes the onset of hepatocellular carcinoma (HCC) in hepatitis C virus (HCV)-infected patients, the effect of occult HBV infection remains unclear. The aim of this study was to investigate the effect of occult HBV infection on the early-onset of HCC in HCV-infected patients. A total of 173 HCC patients with HCV infection were enrolled and classified into 2 groups according to the median age of HCC onset: the early-onset group (n=91; 61.1±5.6 years) and the late-onset group (n=82; 73.8±3.7 years). Independent factors associated with the early-onset of HCC were assessed by multivariate analysis. In the overall analysis, independent risk factors for the early-onset of HCC were the white blood cell count and alanine aminotransferase level, but not the presence of HBV DNA. In a stratification analysis according to albumin levels of ≥3.5 g/dl, the presence of HBV DNA was a significant independent risk factor for the early-onset of HCC (OR 145.18, 95% CI 1.38-15296.61, P=0.036), whereas the presence of antibodies against hepatitis B core antigen was not found to be a risk factor. The presence of HBV DNA was not a risk factor for the early-onset of HCC in the overall analysis. However, its presence was an independent factor for the early-onset of HCC in HCV-infected patients with an albumin level of ≥3.5 g/dl. Thus, occult HBV infection may accelerate hepatocarcino-genesis in HCV-infected patients with relatively low carcinogenic potential.