Apoptosis and Fas system are significantly involved in the process of liver cirrhosis converting into hepatocellular carcinoma

The role of fas/fas ligand system in the pathogenesis of liver cirrhosis and hepatocellular carcinoma

BACKGROUND

The Fas receptor/ligand system including soluble forms is the most important apoptotic initiator in the liver. Dysregulation of this pathway may contribute to abnormal cell proliferation and cell death and is regarded as one of the mechanisms preventing the immune system from rejecting the tumor cells.

OBJECTIVES

To analyze the role of Fas system Fas/ Fas ligand (Fas/ FasL) in the multi-step process of hepatic fibrosis/carcinogenesis, and to use of the serum markers as possible candidate biomarkers for early detection of hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

NINETY PATIENTS WERE ENROLLED: 30 cases of chronic hepatitis C (CHC) without cirrhosis, 30 cases of CHC with liver cirrhosis, and 30 cases of HCC and hepatitis V virus (HCV) infection. Ten wedge liver biopsies, taken during laparoscopic cholecystectomy, were served as normal controls. Serum soluble Fas (sFas) levels were measured using ELISA technique; Fas and FasL proteins were detected in hepatic tissue by indirect Immuno-histochemical technique (IHC); electron microscopic (EM) and immune electron microscopic examinations were performed for detection of Fas expression on lymphocytes.

RESULTS

Hepatic expression of both Fas and FasL as well as expression of Fas on separated lymphocytes were significantly increased in the diseased groups (P < 0. 01) compared to the control specimens. The highest expression was noticed in CHC specimens, particularly with the necro-inflammatory activity and advancement of the fibrosis. The sFas in cirrhotic patients and HCC were significantly higher than that in normal controls and CHC without cirrhosis group (P < 0.01).

CONCLUSIONS

Apoptosis and the Fas system were significantly involved in the process of converting liver cirrhosis into hepatocellular carcinoma. Down-regulation of Fas expression, up regulation of FasL expression in hepatocytes, and elevation of serum sFas levels were important in tumor evasion from immune surveillance, and in hepatic carcinogenesis.

Apoptosis induction in Jurkat cells and sCD95 levels in women's sera are related with the risk of developing cervical cancer

BACKGROUND

Currently, there is clear evidence that apoptosis plays an important role in the development and progression of tumors. One of the best characterized apoptosis triggering systems is the CD95/Fas/APO-1 pathway; previous reports have demonstrated high levels of soluble CD95 (sCD95) in serum of patients with some types of cancer. Cervical cancer is the second most common cancer among women worldwide. As a first step in an attempt to design a minimally invasive test to predict the risk of developing cervical cancer in patients with precancerous lesions, we used a simple assay based on the capacity of human serum to induce apoptosis in Jurkat cells. We evaluated the relationship between sCD95 levels and the ability to induce apoptosis in Jurkat cells in cervical cancer patients and controls.

METHODS

Jurkat cells were exposed to serum from 63 women (20 healthy volunteers, 21 with cervical intraepithelial neoplasia grade I [CIN 1] and 22 with cervical-uterine carcinoma). The apoptotic rate was measured by flow cytometry using Annexin-V-Fluos and Propidium Iodide as markers. Serum levels of sCD95 and soluble CD95 ligand (sCD95L) were measured by ELISA kits.

RESULTS

We found that serum from almost all healthy women induced apoptosis in Jurkat cells, while only fifty percent of the sera from women with CIN 1 induced cell death in Jurkat cells. Interestingly, only one serum sample from a patient with cervical-uterine cancer was able to induce apoptosis, the rest of the sera protected Jurkat cells from this killing. We were able to demonstrate that elimination of Jurkat cells was mediated by the CD95/Fas/Apo-1 apoptotic pathway. Furthermore, the serum levels of sCD95 measured by ELISA were significantly higher in women with cervical cancer.

CONCLUSION

Our results demonstrate that there is a strong correlation between low levels of sCD95 in serum of normal women and higher apoptosis induction in Jurkat cells. We suggest that an analysis of the apoptotic rate induced by serum in Jurkat cells and the levels of sCD95 in serum could be helpful during the prognosis and treatment of women detected with precancerous lesions or cervical cancer.

Changes of cytokines in cirrhosis patients with advanced hepatocellular carcinoma treated by intra-arterial chemotherapy

INTRODUCTION

Tumor necrosis factor (TNF) induces cancer cell-specific apoptosis by binding to a TNF-related apoptosis-inducing ligand. Binding of the Fas ligand on cytotoxic T lymphocytes to the Fas receptor on hepatocytes is also known to induce apoptosis. The aim of this study was to clarify changes of cytokines in patients with liver cirrhosis (LC) and advanced hepatocellular carcinoma (aHCC) receiving intra-arterial combination chemotherapy.

METHODS

Twenty-one adult Japanese LC patients with aHCC received intra-arterial combination chemotherapy. The serum levels of TNF-alpha, soluble TNF receptor-I (sTNFr-I), soluble Fas ligand (sFas L), and soluble Fas (sFas) were evaluated.

RESULTS

Thirteen of the 21 patients (group R) showed an objective response, while the other eight patients (group N) showed no response. The serum level of TNF-alpha was lower after chemotherapy than before chemotherapy in group N, but there was no difference of serum sTNFr-I levels between before and after chemotherapy and there were also no differences between the two groups. The serum sFas levels were higher after chemotherapy than before chemotherapy in group N, while there was no difference among groups.

CONCLUSIONS

These results indicate that a high serum TNF-alpha level and a low serum sFas level might be important for successful combined arterial chemotherapy in LC patients with aHCC.

The role of the tumor necrosis factor (TNF)--Fas L and HCV in the development of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major public health problem in Egypt due to the high prevalence of hepatitis C viral (HCV) infection. The mechanism by which HCV exerts its carcinogenic effect on the liver is not yet understood. Previous research has suggested that perturbations of the Fas-Fas L tumor necrosis system could result in uncontrolled cancerous cell growth in the liver. This study aims to assess the relationship of Fas ligand (Fas L) to HCC. A total of 28 cases (HCC) and 56 controls (28 cirrhosis and 28 chronic hepatitis) were included in the study. Sera and tissue biopsies were tested for HCV antibody and HCV-RNA. Fas ligand expression in tissue was examined immunohistochemically using a rabbit purified polyclonal antibody. Levels of soluble Fas L were determined in serum by ELISA. The HCC cases were graded as: 17.9% Grade I, 32.1% Grade II, 35.7% Grade III and 14.3% were Grade IV. Among the cases, 81% had evidence of cirrhosis. All the cases and controls were positive for HCV-RNA. Tissue and serum PCR results were identical within the same subjects. Fas ligand cytoplasmic expression was more pronounced in HCC than in cirrhosis, and in cirrhosis more than in chronic hepatitis. This expression was higher with increasing grades of malignancy and in tissues adjacent to the tumor, than in those without nearby tumor. Soluble Fas L levels were higher in cases than in controls, with similar results as that of immunohistochemical expression. These results suggest that HCV and Fas ligand play a key role in hepatocarcinogenesis, consistent with the hypothesis that HCV induces overexpression of Fas ligand in the liver cells, resulting in escape from killing by the immune system cells, with subsequent uncontrolled growth of tissue and the development of malignancy.

Apoptosis of blood mononuclear cells in alcoholic liver cirrhosis. The influence of in vitro ethanol treatment and zinc supplementation

Ethanol consumption induces apoptosis in a variety of tissues, among others in liver and lymphoid tissue. Zinc has been shown to influence apoptosis of blood mononuclear cells by inhibiting the mitochondrial pathway of cell death. The aim of this study was to examine the influence of zinc on spontaneous and in vitro alcohol-induced apoptosis of peripheral blood mononuclear cells (PBMCs) of patients with alcoholic cirrhosis. PBMCs were isolated from the blood of 26 patients with cirrhosis and 20 healthy controls. PBMCs and among them CD4+ T helper cells of cirrhotic patients exhibited accelerated spontaneous (without treatment) apoptosis in vitro. When apoptosis was induced in vitro by treating cells with 80 mM ethanol, CD8+ T lymphocytes of a healthy control were more sensitive to ethanol treatment than those of cirrhotic patients. Thirty micromolar zinc supplementation inhibited both spontaneous and ethanol-induced apoptosis of immune cells derived from the blood of the healthy control and cirrhotic patients. In sera of patients with cirrhosis, an elevated level of IL-12, but also sFas (CD95) and sFas ligand (sFasL) was detected. Moreover, in vitro, PBMCs of cirrhotic patients spontaneously released more sFas and sFasL than control PBMCs. Ethanol treatment significantly increased sFas, but decreased sFasL release from PBMCs of cirrhotic patients, while it only slightly affected control cells. As zinc supplementation did not significantly influence sFas or sFasL release, it seems likely that it is rather the mitochondrial pathway of ethanol-related immune cell death that may be inhibited by zinc supplementation.

Apoptotic markers in cancer

In cancer, apoptotic processes occur both spontaneously and induced by antitumor therapies. Qualitative and quantitative changes in cancer cell death along with proliferative alterations are essential determinants in the pathogenesis and progression of malignant disease and its responsiveness to therapy. Besides detecting apoptosis by invasive means in tumor tissue, apoptotic products can be quantified in the circulation. Although circulating apoptotic products usually lack organ and tumor specificity, they contribute in the assessment of disease extent or aggressiveness. The ease of drawing blood facilitates the serial measurement of circulating apoptotic markers to monitor antitumor treatment and predict early response to therapy. This review describes the features of apoptotic and necrotic cell death along with the role the balance between the rates of cell death and cell proliferation plays in the progression of malignancy. The intracellular pathways mediating apoptosis are next summarized. The focus then shifts to the apoptotic markers found in the circulation and their diagnostic, prognostic, predictive, and management utility in cancer.