Different effects of carbon tetrachloride on carcinogen-induced hepatocellular carcinoma and normal liver of the rat: lowered lipid peroxidation and accelerated necrosis in cancer

Chemokine CCL4 Induces Vascular Endothelial Growth Factor C Expression and Lymphangiogenesis by miR-195-3p in Oral Squamous Cell Carcinoma

The inflammatory chemokine (C–C motif) ligand 4 (CCL4) plays an important role in the pathogenesis and progression of cancer. In particular, higher serum CCL4 levels in patients with oral squamous cell carcinoma (OSCC) are associated with a more advanced stage of disease. OSCC accounts for approximately 95% of oral cancer in Taiwan and has a poor prognosis, due to aggressive local invasion and metastasis, leading to recurrence. OSCC spreads preferentially through lymphatic vessels and has the propensity to metastasize to the cervical lymph nodes even in the early stage of disease. Vascular endothelial growth factor C (VEGF-C) is an essential regulator of lymphangiogenesis. In particular, VEGF-C is specific to lymphatic vessel development, and VEGF-C expression levels have been found to directly correlate with lymph node metastasis in OSCC. However, it is unclear as to whether CCL4 correlates with VEGF-C expression and lymphangiogenesis in OSCC. We found that CCL4 increased VEGF-C expression and promoted lymphangiogenesis in oral cancer cells in vitro and in vivo. miR-195-3p mimic reversed CCL4-enhanced VEGF-C expression. CCL4 stimulation of oral cancer cells augmented JAK2 and STAT3 phosphorylation. Thus, CCL4 may be a new molecular therapeutic target for inhibition of lymphangiogenesis and metastasis in OSCC.

Differentiation of necrotic cell death with or without lysosomal activation: application of acute liver injury models induced by carbon tetrachloride (CCL4) and dimethylnitrosamine (DMN)

We investigated the relationship between DNA degradation and lysosome activity (loss of lysosomal integrity) in necrotic cell death induced by carbon tetrachloride (CCl4) and dimethylnitrosamine (DMN): coagulation necrosis and hemorrhagic necrosis, respectively. TdT-mediated dUTP-biotin nick end-labeling (TUNEL) and enzyme histochemistry for acid phosphatase were performed in both models and results were analyzed by light microscopy, electron microscopy, and confocal laser scanning microscopy (CLSM). In the CCl(4)-injected liver, TUNEL staining was closely associated with release of lysosomal enzymes into the cytoplasm, and intranuclear deposition of lysosomal enzymes took place at an early stage of subcellular damage. In the DMN-injected liver, TUNEL-positive nuclei tended to have well-preserved lysosomes and centrally localized TUNEL signals. It was assumed that acute hepatocellular damage in the CCl4-injected liver would be characterized by necrotic cell death with lysosome activation and that damage in the DMN-injected liver would be necrotic cell death without lysosome activation. In the DMN-injected liver, DNA degradation may be selectively induced in the nuclear center, in which heterochromatin (including inactive chromatin) is believed to be a target. We concluded that necrotic cell death, i.e., DNA degradation, would be at least divided into two types, with/without association with lysosome activation, represented by necrotic cell death in the CCl4-injected liver and that in the DMN-injected liver.

Effects of dietary polyunsaturated fatty acids and nucleotides on tissue fatty acid profiles of rats with carbon tetrachloride-induced liver damage

The deficiency of polyunsaturated fatty acids (PUFA) that occurs in plasma of patients with liver cirrhosis has been assessed in rats with severe steatosis and mild liver necrosis induced by repeated administration of low doses of carbon tetrachloride (CCl(4)). The contribution of both dietary (n-3) long-chain PUFA and nucleotides to the recovery of the altered fatty acid profiles of tissue lipids of these rats has also been studied. Two groups of rats were used. The first was intraperitoneally injected 0.15 ml of a 10% (v/v) CCl(4)solution in paraffin per 100 g of body weight, three times a week for 9 weeks; the second received paraffin alone. After the treatment, six rats of each group were killed. Afterwards, the remaining controls were fed a semipurified diet (SPD) for 3 weeks, and the remaining rats in the CCl(4)group were divided into three new groups: the first was fed the SP diet; the second was fed the SP diet supplemented with 1% (n-3) polyunsaturated fatty acids (PUFA diet); and the third was fed the SP diet supplemented with 250 mg nucleotides per 100 g diet (NT diet). Fatty acids of plasma, erythrocyte membranes and liver microsomes were analyzed. Decreases in linoleic and arachidonic acids in both total plasma lipids and liver microsomal phospholipids were the main findings due to CCl(4)treatment. The rats that received CCl(4)and the PUFA diet showed the lowest levels of (n-6) PUFA and the highest levels of (n-3) PUFA in liver microsomal phospholipids, as well as a significant increase of (n-3) PUFAs in total plasma lipids. The animals that received the NT diet showed no signs of fatty infiltration and exhibited the highest levels of (n-6) PUFAs in liver microsomal phospholipids. These results show that CCl(4)affects fatty acid metabolism which is accordingly reflected in altered tissue fatty acid profiles, and that balanced diets containing PUFA and nucleotides are important for the recovery of the damaged liver in rats.

Immunohistochemical localization of glutathione peroxidase, a lipid peroxidase scavenger, in atherosclerotic lesions of human arteries

The localization of glutathione peroxidase (GSH-PO) in the human arteriosclerotic lesions was investigated by immunohistochemical methods. GSH-PO is an enzyme that effectively reduces lipid peroxides. It is also known that its synthesis is significantly increased by lipid peroxides, the substrate of the enzyme. Accordingly, the increased expression of GSH-PO would indicate the promotion of lipid peroxidation in the site. Immunohistochemistry for Apo-B protein, the major protein component of plasma low density lipoprotein (LDL), was also performed to show the amount of plasma LDL permeation and deposition on the arterial wall. Atheromatous plaques contained numerous GSH-PO positive cells with foamy cytoplasm, while normal arterial walls were almost devoid of GSH-PO positive cells. Immunoelectron microscopically, the GSH-PO reaction products were observed diffusely in the cytoplasm of these cells. The deposition of Apo-B was closely related to the localization of GSH-PO positive cells in the atheromatous lesions. These findings suggest that the lipid peroxidation that surpasses the protective actions of GSH-PO may cause foamy change of smooth muscle cells and macrophages to ultimately form atherosclerotic lesions.

Lipoproteins in hypoxic tumor cells as traps of free radicals

We examined the role of main cell protective mechanisms in retaining the high resistance of ascitic cells (EAC, ZAH) to lipid peroxidation with respect to different stages of tumor-organism metabolic interactions. The following mechanisms were studied: (1) the activity of main EAC enzymatic antioxidants (GSH-Px, SOD); (2) changes in lipid metabolism, especially the content of the main PUFA (linoleic and arachidonic fatty acids) in EAC cells; (3) comparison of intracellular resistance between EAC/ZAH cytoplasmic sections (containing LP-granules or not) to lipid peroxidation (initialized directly by UV-light). We found that the high resistance to lipid peroxidation was typical for cytoplasma sections (without LP-granules) on all stages of tumor development in vivo. The intracellular LP-granules become the main sensitive targets for FR-action, but only in the chronic hypoxia state of EAC/ZAH tumor cells. The latter effect developed in close correlation with the following metabolic interactions: (1) increasing the proportion of PUFA (especially, arachidonic and linoleic acids) transported to EAC tumor cells from host organs and accumulated mainly in tumor LP-granules, and (2) decreasing the alpha-tocopherol content of these hypoxic EAC cells while no activation of the main cell antioxidative enzymes (GSH-Px, SOD) took place. The vitality and high resistance of EAC stationary cells were accompanied by the 'paradoxical' state with great differences between the resistance of the intracellular PUFA-rich granules and other cytoplasmic sections. A similar state was found in stationary ZAH cells. The cell state is in good agreement with the Dormandy's suggestion that PUFA-rich granules can trap reactive radical species preventing their interaction with 'critical' PUFA-membranes.