Evaluation of Cardiotonic Steroid Modulation of Cellular Cholesterol and Phospholipid.

We have previously shown that 21-benzylidene digoxin (21-BD) increases the total cholesterol and phospholipid content on the membrane of HeLa cells. Lipid modulation caused by cardiotonic steroids (CTS) is still unexplored. Therefore, the aim of the present study was to evaluate the cholesterol and phospholipid modulation of the cell membrane caused by ouabain and 21-BD and the possible involvement of the caveolae on this modulation. For this, one cell line containing caveolae (HeLa) and other not containing (Caco-2) were used. The modulation of the lipid profile was evaluated by total cholesterol and phospholipids measurements, and identification of membrane phospholipids by HPTLC. The cholesterol distribution was evaluated by filipin staining. The caveolin-1 expression was evaluated by Western Blotting. Ouabain had no effect on the total membrane lipid content in both cell lines. However, 21-BD increased total membrane phospholipid content and had no effect on the membrane cholesterol content in Caco-2 cells. CTS were not able to alter the specific phospholipids content. In the filipin experiments, 21-BD provoked a remarkable redistribution of cholesterol to the perinuclear region of HeLa cells. In Caco-2 cells, it was observed only a slight increase in cholesterol, especially as intracellular vesicles. The caveolin-1 expression was not altered by any of the compounds. Our data mainly show different effects of two cardiotonic steroids. Ouabain had no effect on the lipid profile of cells, whereas 21-BD causes important changes in cholesterol and phospholipid content. Therefore, the modulation of cholesterol content in the plasma membrane of HeLa cells is not correlated with the expression of caveolin-1.

Tumor Tissue Oxidative Stress Changes and Na, K-ATPase Evaluation in Head and Neck Squamous Cell Carcinoma.

Changes in metabolism are mechanisms that are largely implicated in the development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC) and also in resistance to different anticancer therapies. Identification of biomarkers for differentiation between cancerous and normal epithelium, treatment design and prognosis remain a vital issue in the field of head and neck cancer. The present study analyzed the main biochemical changes that occur in HNSCC tumors by through mechanisms involving oxidative stress. The release of substances reactive to thiobarbituric acid was significantly lower in HNSCC tumor tissue as compared to healthy tissue. The assays related to the lipid profile assays showed changes in membrane biophysics of tumor cells due to an increase in total phospholipids and total cholesterol, as well as an increased activity and expression of the α1 subunit of Na, K-ATPase, which is fundamental in the process of carcinogenesis. The modulation of the antioxidant system was also affected, with a decrease in the catalytic activity of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as a reduction of glutathione (GSH) content and an increase in H2O2 content. A reduction in catalase (CAT) activity was observed. The data presented here are in accordance with important findings described by us in a previous study, involving the same individuals, but with a focus on the damage generated in red blood cells, resulting from tumor installation. Therefore, it was possible to conclude that the biochemical alterations found in HNSCC cells are fundamental for transformation and maintenance of the tumor cell and once it is installed, it is also capable of generating injuries in the patients' red blood cells. Our data demonstrate that this could be a promising biomarker for HNSCC.

Evaluation of the Erythrocyte Membrane in Head and Neck Cancer Patients.

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous and complex disease, both from a clinical and molecular point of view. The prolonged use of alcohol and tobacco, along with the release of tumor secretions can modulate blood cells, such as erythrocytes. Here, this study was conducted with 24 patients diagnosed with HNSCC and an equal number of healthy individuals are matched by age and gender. The levels of lipid peroxidation were measured using the individual plasma, while for lipid concentrations, identification and quantification Na, K-ATPase activity and osmotic fragility, the red blood cell concentrate were used. The release of TBARS was significantly higher in patients with HNSCC. The lipid profile assays demonstrated a rearrangement of the erythrocyte membrane due to a decrease in total phospholipids and phosphatidylethanolamine followed by an increase in total cholesterol and phosphatidylcholine. Na, K-ATPase activity also increased. Erythrocytes were more fragile in patients with HNSCC than in health individuals. Therefore, the membrane of erythrocytes were rearranged and Na, K-ATPase function altered in the HNSCC patients. Our findings suggests that the alcohol, tobacco and tumor secretion modulate in a specific manner that the erythrocytes membranes of these patients making this system a potential tool for HNSCC biomarker of tumor progression.